Category: Precision Oncology

Overall Survival at 2 Years with LUMAKRAS® for KRAS G12C Positive Non Small Cell Lung Cancer

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SUMMARY: The American Cancer Society estimates that for 2022, about 236,740 new cases of lung cancer will be diagnosed and 135,360 patients will die of the disease. Lung cancer is the leading cause of cancer-related mortality in the United States. Non-Small Cell Lung Cancer (NSCLC) accounts for approximately 85% of all lung cancers. Of the three main subtypes of NSCLC, 30% are Squamous Cell Carcinomas (SCC), 40% are Adenocarcinomas and 10% are Large Cell Carcinomas. With changes in the cigarette composition and decline in tobacco consumption over the past several decades, Adenocarcinoma now is the most frequent histologic subtype of lung cancer.

The KRAS (kirsten rat sarcoma viral oncogene homologue) proto-oncogene encodes a protein that is a member of the small GTPase super family. The KRAS gene provides instructions for making the KRAS protein, which is a part of a signaling pathway known as the RAS/MAPK pathway. By relaying signals from outside the cell to the cell nucleus, the protein instructs the cell to grow, divide and differentiate. The KRAS protein is a GTPase, and converts GTP into GDP. To transmit signals, the KRAS protein must be turned on, by binding to a molecule of GTP. When GTP is converted to GDP, the KRAS protein is turned off or inactivated, and when the KRAS protein is bound to GDP, it does not relay signals to the cell nucleus. The KRAS gene is in the Ras family of oncogenes, which also includes two other genes, HRAS and NRAS. When mutated, oncogenes have the potential to change normal cells cancerous.

KRAS is the most frequently mutated oncogene in human cancers and are often associated with resistance to targeted therapies and poor outcomes. The KRAS-G12C mutation occurs in approximately 12-15% of Non Small Cell Lung Cancers (NSCLC) and in 3-5% of colorectal cancers and other solid cancers. KRAS G12C is one of the most prevalent driver mutations in NSCLC and accounts for a greater number of patients than those with ALK, ROS1, RET, and TRK 1/2/3 mutations combined. KRAS G12C cancers are genomically more heterogeneous and occur more frequently in current or former smokers, and are likely to be more complex genomically than EGFR mutant or ALK rearranged cancers. G12C is a single point mutation with a Glycine-to-Cysteine substitution at codon 12. This substitution favors the activated state of KRAS, resulting in a predominantly GTP-bound KRAS oncoprotein, amplifying signaling pathways that lead to oncogenesis.Inhibiting-KRAS-G12C

LUMAKRAS® (Sotorasib) is a first-in-class small molecule that specifically and irreversibly inhibits KRAS-G12C and traps KRAS-G12C in the inactive GDP-bound state. Preclinical studies in animal models showed that LUMAKRAS® inhibited nearly all detectable phosphorylation of Extracellular signal-Regulated Kinase (ERK), a key downstream effector of KRAS, leading to durable complete regression of KRAS-G12C tumors. The CodeBreaK clinical development program for LUMAKRAS® was designed to treat patients with an advanced solid tumor with the KRAS G12C mutation and address the longstanding unmet medical need for these cancers. This program has enrolled more than 800 patients across 13 tumor types since its inception.

CodeBreaK 100 is a Phase I and II, first-in-human, open-label, single arm, multicenter study, which enrolled patients with KRAS G12C-mutant solid tumors. Eligible patients must have received a prior line of systemic anticancer therapy, for their tumor type and stage of disease. The Phase II trial enrolled 126 patients with NSCLC, who had locally advanced or metastatic NSCLC with a KRAS G12C mutation, and had progressed on an immune checkpoint inhibitor and/or platinum-based chemotherapy. Patients with active brain metastases were excluded. Patient received LUMAKRAS® 960 mg orally once daily, until disease progression or unacceptable toxicity. The median age was 64 years, 52% were male, over 90% of patients had a smoking history, median number of prior lines of therapy was two, 92% had prior platinum-based chemotherapy and 90% had prior anti–PD-L1 therapy, 83% had both prior platinum-based chemotherapy and immunotherapy. The Primary end point of the trial was Overall Response Rate (ORR) as assessed by blinded Independent Central Review. Secondary end points included Duration of Response (DOR), Disease Control Rate (DCR), time to recovery, Progression Free Survival (PFS), Overall Survival (OS), and Safety. The examination of biomarkers served as an exploratory end point.

At the time of Primary analysis, at a median follow up of 12.2 months, the ORR was 37.1% and the median Duration of Response was 10 months. Based on the data from the primary analysis, the FDA in 2021 granted accelerated approval to LUMAKRAS®, for the treatment of patients with locally advanced or metastatic NSCLC, whose tumors harbor the KRAS G12C mutation, and who have received prior therapies.

For this updated analysis, the median follow up time for OS was 24.9 months, and the researchers included 174 patients enrolled in Phase I (N=48) and Phase II (N=126) portions of the CodeBreaK 100 trial, who were treated with LUMAKRAS®. The Overall Response Rate was 40.7% and the Disease Control Rate (DCR) was 83.7%. The median time to response was 6 weeks, the median Duration of Response was 12.3 month and 50.6% of responders remained in response for 12 months or more. The median PFS was 6.3 months and the median OS showed no change in the updated analysis, and was 12.5 months. At 1-year, the OS rate was 50.8% and the 2-year Overall Survival was 32.5%. The researchers performed additional analyses on both tumor and blood samples to identify biomarker profiles associated with durable clinical benefit and these showed that prolonged clinical benefit was observed regardless of Tumor Mutation Burden, PDL1 expression, and STK11 co-mutation status. Grade 3 or 4 treatment-related Adverse Events occurred in 21% of patients. Most adverse events were Grade 1 or 2, and treatment-related adverse events occurring in more than 10% of patients included diarrhea, elevated liver enzymes, nausea and fatigue.

It was concluded from this updated analysis that this is the longest follow up of patients on any KRAS G12C inhibitor, and LUMAKRAS® demonstrated meaningful and durable efficacy in patients with KRAS mutated NSCLC for whom treatment options are limited, following progression on first line treatment, and historically have had poor outcomes. Patients on LUMAKRAS® benefitted regardless of Tumor Mutation Burden, PDL1 expression, and STK11 co-mutation status. A global Phase III study (CodeBreaK 200) is underway, comparing LUMAKRAS® to Docetaxel in patients with KRAS G12C-mutated NSCLC.

Long-term outcomes with sotorasib in pretreated KRASp.G12C-mutated NSCLC: 2-year analysis of CodeBreaK100. Dy GK, Govindan R, Velcheti V, et al. Presented at: 2022 AACR Annual Meeting; April 8-13, 2022, New Orleans, LA. Abstract CT008.

Early-Stage Multi-Cancer Detection Using an Extracellular Vesicle Protein-Based Blood Test

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SUMMARY: The American Cancer Society’s estimates that in 2022, about 62,210 people will be diagnosed with pancreatic cancer and 49,830 people will die of the disease, 19,880 women will receive a new diagnosis of ovarian cancer and about 12,810 women will die of the disease, and about 81,800 new cases of bladder cancer will be diagnosed in 2022 and about 17,100 patients will die of the disease. These three cancer types are estimated to account for approximately 80,000 deaths in the US in 2022. Detecting cancer at early stages can significantly increase survival rates and outcomes.

Several multi-cancer early detection tests are being developed that involve blood-based circulating cell-free tumor DNA (cfDNA) in the plasma, to track hundreds of patient-specific mutations, to detect Minimal Residual Disease (MRD) , as well as detection of abnormal methylation patterns, followed by machine learning approaches, to differentiate between cancer and non-cancer, for detecting clinically significant, late-stage (III and IV) cancers. Early detection of cancer however is the key to improving survival. This is particularly relevant for certain cancer types. Pancreatic Ductal AdenoCarcinoma (PDAC) is one of the deadliest cancers, and a leading cause of all cancer-related deaths in the United States, and is typically detected when the disease is advanced. However, when detected at Stage I, survival rates can be as high as 80%. Ovarian cancer is often detected when the disease is advanced and the 5-year survival rates are less than 30%, but can be as high as 93% when detected early. The same holds true for metastatic bladder cancer, with 5-year survival rates of only 6%, whereas while detected when the tumor is still localized to the bladder wall inner layer results in a 5-year survival rate of 96%. Even though serum CA19-9 is intended as an aid in the management of patients with confirmed pancreatic cancer for serial monitoring of their response to therapy and disease progression, it is not recommended by the FDA for screening, as it may be elevated in several benign conditions. Similarly, serum CA-125 is FDA approved for use in monitoring patients with ovarian cancer for disease persistence and recurrence, but is not recommended to screen for ovarian cancer. Currently, there are few general screening strategies to detect asymptomatic, early-stage PDAC, ovarian, or bladder cancer and there is therefore a significant unmet need in this patient group.

Exosomes are 30-150 nm-sized Extracellular Vesicles (EVs) secreted by multiple different cell types and ejected by tumors into the bloodstream. They mediate intercellular signaling by transferring mRNAs and microRNAs between distant cells and tissues and therefore carry functional protein biomarkers representing the tumor proteome. Exosomes represent one potential approach for more sensitive detection of cancer-related biomarkers from blood.

The researchers in this study used an Alternating Current Electrokinetic (ACE)-based platform (Verita™ System) to efficiently isolate EVs from soluble contaminants such as cells, small proteins, or other vesicles from patient samples, and then measured the concentrations of associated protein biomarkers (“EV proteins”) present in the purified EV samples from our case-control study subjects. The researchers chose this platform over the current gold standard ultracentrifugation method, which the authors felt was inefficient and not suitable for point-of-care applications. Artificial Intelligence machine-learning algorithm developed by the researchers, enabled detection of early-stage pancreatic, ovarian, and bladder cancers.

In this case-control pilot study, 139 pathologically confirmed Stage I and II cancer cases representing pancreatic, ovarian, or bladder patients were compared with 184 control subjects, using the Verita™ System. The Extracellular Vesicles (EVs) isolated using this technology, were consistent with the presence of Exosomes, in accordance with the International Society for Extracellular Vesicles (ISEV) 2018 guidelines. The researchers selected a panel of 13 Extracellular Vesicle (EV) proteins along with age, a known cofactor in cancer. In order to simulate a real-world screening scenario, all cancer cases were treatment-naïve and to ensure that these were early-stage patients, the histopathologic staging was confirmed using the American Joint Commission on Cancer (AJCC) guidelines. The median age of the cancer cases was 60 years and 63.3% of the overall cancer cases were Stage I, with the remaining 36.7% at Stage II. The median age of the control group was 57 years and had no known history of cancer, autoimmune diseases, neurodegenerative disorders or diabetes mellitus.

When the overall cancer case cohort was compared with the control individuals using the EV protein biomarker test, the average sensitivity was 71.2%, at a specificity of 99.5%. When considered across all the three cancers studied, EV protein biomarker test using this technology demonstrated similar sensitivities of 70.5% and 72.5% for Stage I and II patients, respectively. This new technology detected 95.5% of Stage I pancreatic cancers, 73.1% of pathologic Stage IA lethally aggressive serous ovarian adenocarcinomas and 43.8% in bladder cancer, demonstrating the potential value of this platform for detection of early stage cancers. The lower sensitivity for detecting early stage bladder cancer may be due to high molecular and histologic heterogeneity of bladder tumors.

It was concluded from this study that blood-based EV protein detection test has potential clinical value for early cancer detection and the use of Verita™ platform resulted in the accurate detection of early stage pancreatic, ovarian, or bladder cancer. The authors added that mortality from pancreatic cancer which will soon become the second leading cause of cancer mortality in the U.S., can be greatly reduced if this study results are validated.

Early-stage multi-cancer detection using an extracellular vesicle protein-based blood test. Hinestrosa, J.P., Kurzrock, R., Lewis, J.M. et al. Commun Med 2, 29 (2022). https://doi.org/10.1038/s43856-022-00088-6.

FDA Approves PSMA Targeted Therapy for Metastatic Castrate Resistant Prostate Cancer

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SUMMARY: The FDA on March 23, 2022, approved PLUVICTO® (Lutetium Lu 177 vipivotide tetraxetan) for the treatment of adult patients with Prostate-Specific Membrane Antigen (PSMA)-positive metastatic Castration-Resistant Prostate Cancer (mCRPC), who had been treated with Androgen Receptor (AR) pathway inhibition and Taxane-based chemotherapy. The FDA also approved LOCAMETZ® (Gallium Ga 68 gozetotide), a radioactive diagnostic agent for Positron Emission Tomography (PET) of PSMA-positive lesions, including selection of patients with metastatic prostate cancer for whom PLUVICTO® PSMA-directed therapy is indicated. LOCAMETZ® is the first radioactive diagnostic agent approved for patient selection in the use of a radioligand therapeutic agent.

The development and progression of prostate cancer is driven by androgens. Androgen Deprivation Therapy (ADT) or testosterone suppression has therefore been the cornerstone of treatment of advanced prostate cancer, and is the first treatment intervention. Approximately 10-20% of patients with advanced Prostate cancer will progress to Castration Resistant Prostate Cancer (CRPC) within five years during ADT, and over 80% of these patients will have metastatic disease at the time of CRPC diagnosis. Among those patients without metastases at CRPC diagnosis, 33% are likely to develop metastases within two years. Progression to Castration Resistant Prostate Cancer (CRPC) often manifests itself with a rising PSA (Prostate Specific Antigen) and the estimated mean survival of patients with CRPC is 9-36 months, and there is therefore an unmet need for new effective therapies.

Prostate-Specific Membrane Antigen (PSMA) is a Type II cell membrane glycoprotein that is selectively expressed in prostate cells, with high levels of expression in prostatic adenocarcinoma. PSMA is a therefore an excellent target for molecular imaging and therapeutics, due to its high specificity for prostate cancer.

PLUVICTO® is a radiopharmaceutical that targets PSMA. It is comprised of Lutetium-177, a cytotoxic radionuclide , linked to the ligand PSMA-617, a small molecule designed to bind with high affinity to PSMA. Radioligand therapy with PLUVICTO® targets PSMA and releases its payload of lethal beta radiation into the prostate cancer cell. The antitumor activity and safety PLUVICTO® have been established previously in a Phase II study (Lancet Oncol. 2018;19:825-833).

VISION is an international, randomized, open-label Phase III study in which the benefit of PLUVICTO® was evaluated in men with PSMA-positive mCRPC, previously treated with second generation Androgen Receptor signaling pathway inhibitor (XTANDI® -Enzalutamide or ZYTIGA®-Abiraterone acetate), and 1 or 2 taxane chemotherapy regimens. In this trial, 831 patients were randomized 2:1 to receive PLUVICTO® 7.4 GBq (200 mCi) every 6 weeks for up to a total of 6 cycles plus Standard of Care as determined by the treating physician (N=551), or Standard of Care only (N=280). Both treatment groups were well balanced and this trial excluded patients treated with XOFIGO® (Radium-223). All enrolled patients received a GnRH analog or had prior bilateral orchiectomy and had a castrate level or serum/plasma testosterone of lower than 50ng/dL. PET imaging with LOCAMETZ® was used to determine PSMA positivity by central review. PSMA-positive mCRPC was defined as having at least one tumor lesion with LOCAMETZ® uptake greater than normal liver. Patients were excluded from enrollment if any lesions exceeding certain size criteria in the short axis had uptake less than or equal to uptake in normal liver. The Primary endpoints were radiographic Progression Free Survival (rPFS) by Independent Central Review (ICR) and Overall Survival (OS). Secondary endpoints included Objective Response Rate (ORR), Disease Control Rate (DCR), and time to first Symptomatic Skeletal Event (SSE). The median study follow up was 20.9 months.

Treatment with the combination of PLUVICTO® plus Standard of Care resulted in a statistically significant improvement in the Primary endpoints of Overall Survival and radiographic Progression Free Survival. PLUVICTO® plus Standard of Care significantly improved rPFS by 60%, compared to Standard of Care alone (median rPFS 8.7 versus 3.4 months, HR=0.40; P<0.001). The median OS was also significantly improved by 38% in the study group (median OS 15.3 versus 11.3 months, HR=0.62; P<0.001). All key secondary endpoints including Objective Response Rate, Disease Control Rate, and time to first Symptomatic Skeletal Event were statistically significant, and in favor of PLUVICTO® plus Standard of Care. The most common adverse reactions in patients receiving PLUVICTO® were fatigue, dry mouth, nausea, decreased appetite, constipation, anemia, lymphopenia, thrombocytopenia, hypocalcemia and hyponatremia.

It was concluded that radioligand therapy with PLUVICTO® significantly improved radiographic Progression Free Survival and Overall Survival when added to Standard of Care, compared with Standard of Care alone, in men with PSMA-positive metastatic Castration Resistant Prostate Cancer.

Lutetium-177-PSMA-617 for Metastatic Castration-Resistant Prostate Cancer. Sartor O, de Bono J, Chi KN, et al. N Engl J Med 2021; 385:1091-1103.

LYNPARZA® Superior to Next-Generation Hormonal Drug in CRPC Patients with Homologous Recombination Repair Gene Alterations

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SUMMARY: Prostate cancer is the most common cancer in American men with the exclusion of skin cancer, and 1 in 9 men will be diagnosed with Prostate cancer during their lifetime. It is estimated that in the United States, about 268,490 new cases of Prostate cancer will be diagnosed in 2022 and 34,500 men will die of the disease. The development and progression of Prostate cancer is driven by androgens. Androgen Deprivation Therapy (ADT) or testosterone suppression has therefore been the cornerstone of treatment of advanced Prostate cancer and is the first treatment intervention. Approximately 10-20% of patients with advanced Prostate cancer will progress to Castration Resistant Prostate Cancer (CRPC) within five years during ADT, and over 80% of these patients will have metastatic disease at the time of CRPC diagnosis. The malignant transformation of prostatic epithelial cell as well as the development of CRPC has been attributed to deleterious alterations in a variety of genes including loss-of-function alterations in Homologous Recombination Repair (HRR) genes.

DNA damage is a common occurrence in daily life by UV light, ionizing radiation, replication errors, chemical agents, etc. This can result in single and double strand breaks in the DNA structure which must be repaired for cell survival. The two vital pathways for DNA repair in a normal cell are BRCA1/BRCA2 and PARP. BRCA1 and BRCA2 are tumor suppressor genes that recognize and repair double strand DNA breaks via Homologous Recombination Repair (HRR) pathway. Homologous Recombination is a type of genetic recombination, and is a DNA repair pathway utilized by cells to accurately repair DNA double-stranded breaks during the S and G2 phases of the cell cycle, and thereby maintain genomic integrity. Homologous Recombination Deficiency (HRD) is noted following mutation of genes involved in HR repair pathway. At least 15 genes are involved in the Homologous Recombination Repair (HRR) pathway including BRCA1, BRCA2, PALB2, CHEK2 and ATM genes. Mutations in these genes predispose an individual to develop malignant tumors. Mutations in BRCA1 and BRCA2 account for about 20-25% of hereditary breast cancers and about 5-10% of all breast cancers. They also account for 15% of ovarian cancers, in addition to other cancers such as Colon and Prostate. BRCA mutations can either be inherited (Germline) and present in all individual cells or can be acquired and occur exclusively in the tumor cells (Somatic). Somatic mutations account for a significant portion of overall BRCA1 and BRCA2 aberrations. Loss of BRCA function due to frequent somatic aberrations likely deregulates HR pathway, and other pathways then come in to play, which are less precise and error prone, resulting in the accumulation of additional mutations and chromosomal instability in the cell, with subsequent malignant transformation. Homologous Recombination Deficiency therefore indicates an important loss of DNA repair function.

The PARP (Poly ADP Ribose Polymerase), family of enzymes include, PARP1 and PARP2, and is a related enzymatic pathway that repairs single strand breaks in DNA. In a BRCA mutant, the cancer cell relies solely on PARP pathway for DNA repair to survive. PARP inhibitors trap PARP onto DNA at sites of single-strand breaks, preventing their repair and generating double-strand breaks that cannot be repaired accurately in tumors harboring defects in Homologous Recombination Repair pathway genes, such as BRCA1 or BRCA2 mutations, and this leads to cumulative DNA damage and tumor cell death.

LYNPARZA® (Olaparib) is a first-in-class PARP inhibitor and blocks DNA damage response in tumors harboring a deficiency in Homologous Recombination Repair, as is noted in those with mutations such as BRCA1 and/or BRCA2. LYNPARZA® showed promising results in a Phase II trial (TOPARP), when given as monotherapy, in patients with BRCA1/2 or ATM gene-mutated mCRPC, who had received a prior Taxane-based chemotherapy, and at least one newer hormonal agent (ZYTIGA® or XTANDI®).

PROfound is a prospective, multicentre, randomized, open-label, Phase III trial in which the efficacy and safety of LYNPARZA® was compared with physician’s choice of either XTANDI® or ZYTIGA® in two groups of patients with mCRPC, who had progressed on prior treatment with new hormonal anticancer treatments, and had a qualifying tumor mutation in one of 15 genes involved in the Homologous Recombination Repair (HRR) pathway. Patients in Cohort A (N=245) had alterations in BRCA1, BRCA2 or ATM genes while those in Cohort B (N=142) had alterations in any one of 12 other genes known to be involved in DNA repair which included BRIP1, BARD1, CDK12, CHEK1, CHEK2, FANCL, PALB2, PPP2R2A, RAD51B, RAD51C, RAD51D or RAD54L. Patients were randomized 2:1 within each cohort to receive LYNPARZA® 300 mg orally BID or physician’s choice of XTANDI® 160 mg orally QD or ZYTIGA® 1000 mg orally QD along with Prednisone 5 mg orally BID. Patient characteristics were well-balanced between arms in each treatment group, median patient age was 68 years, approximately 25% of patients had de novo metastatic disease, about 65% of patients received prior Taxane therapy and more than 20% had received two lines of chemotherapy. Patients were allowed to cross over to LYNPARZA® upon progression. The Primary endpoint was radiographic Progression-Free Survival (rPFS) in Cohort A, assessed by Blinded Independent Central Review (BICR).

The authors had previously reported that in Cohort A, the median PFS was 7.4 months with LYNPARZA®, compared to 3.5 months in the control group (HR=0.34, P<0.0001). This represented a 66% greater delay in disease progression compared to hormonal therapy. The interim Overall Survival analysis in Cohort A showed that median OS was 18.5 months with LYNPARZA® compared to 15 months with control drug treatment (HR=0.64, P=0.0173). In Cohort A, the Objective Response Rate (ORR) was 33.3% with LYNPARZA® compared with 2.3% with control drug therapies (P<0.0001).

The authors in this publication reported the results of the prespecified Secondary endpoints, which included pain, Health-Related Quality of Life (HRQOL), symptomatic Skeletal-Related Events, and time to first opiate use for cancer-related pain in Cohort A group of patients. Pain was assessed with the Brief Pain Inventory-Short Form, and HRQOL was assessed with the Functional Assessment of Cancer Therapy-Prostate (FACT-P). Cohort A included 245 patients with alterations in BRCA1, BRCA2, or ATM genes, of whom 162 patients received the investigational agent LYNPARZA®, and 83 patients received control drug. The median duration of follow up at data cutoff was 6.2 months for all LYNPARZA® group patients and 3.5 months for the control group patients.

The median time to pain progression was significantly longer with LYNPARZA® and was Not Reached in the LYNPARZA® group versus 9.92 months in the control group (HR=0.44; P=0.019). Pain interference scores were also significantly better in the LYNPARZA® group (difference in overall adjusted mean change from baseline score −0.85; nominal P=0.0004). Median time to progression of pain severity was Not Reached in either group. Among patients who had not used opiates at baseline (113 in the LYNPARZA® group, 58 in the control group), median time to first opiate use for cancer-related pain was 18.0 months in the LYNPARZA® group versus 7.5 months in the control group (HR=0.61; nominal P=0.044).

The proportion of patients with clinically meaningful improvement in FACT-P total score during treatment was higher for the LYNPARZA® group than the control group (10% versus 1% respectively; odds ratio=8.32; nominal P=0.0065). The median time to first symptomatic Skeletal-Related Event was not reached for either treatment group and the proportions of patients remaining free of symptomatic Skeletal-Related Events were 89.5% versus 77.1% at 6 months and 77.6% versus 53.6% at 12 months, in the LYNPARZA® and control groups respectively.

It was concluded that LYNPARZA® was associated with reduced pain burden and better-preserved HRQOL compared with the two control drugs, in patients with metastatic Castration-Resistant Prostate Cancer and Homologous Recombination Repair gene alterations, who had disease progression after a previous next-generation hormonal drug. The authors added that the study findings support the clinical benefit of improved radiographical Progression Free Survival and Overall Survival identified in PROfound trial.

Pain and health-related quality of life with olaparib versus physician’s choice of next-generation hormonal drug in patients with metastatic castration-resistant prostate cancer with homologous recombination repair gene alterations (PROfound): an open-label, randomised, phase 3 trial. Thiery-Vuillemin A, de Bono J, Hussain M, et al. Published:February 11, 2022. DOI:https://doi.org/10.1016/S1470-2045(22)00017-1

Cancer Risks Associated With BRCA1 and BRCA2 Pathogenic Variants

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SUMMARY: DNA damage is a common occurrence in daily life by UV light, ionizing radiation, replication errors, chemical agents, etc. This can result in single and double strand breaks in the DNA structure which must be repaired for cell survival. The vital pathways for DNA repair in a normal cell are BRCA1/BRCA2 and PARP. BRCA1 and BRCA2 genes recognize and repair double strand DNA breaks via Homologous Recombination Repair (HRR) pathway. Homologous Recombination is a type of genetic recombination, and is a DNA repair pathway utilized by cells to accurately repair DNA double-stranded breaks during the S and G2 phases of the cell cycle, and thereby maintain genomic integrity. Homologous Recombination Deficiency (HRD) is noted following mutation of genes involved in HR repair pathway.

BRCA1 and BRCA2 are tumor suppressor genes located on chromosome 17 and chromosome 13 respectively and functional BRCA proteins repair damaged DNA, and play an important role in maintaining cellular genetic integrity. They regulate cell growth and prevent abnormal cell division and development of malignancy. Mutations in these genes predispose an individual to develop malignant tumors. It is well established that the presence of BRCA1 and BRCA2 mutations can significantly increase the lifetime risk for developing breast and ovarian cancer, as high as 85% and 40% respectively.

BRCA mutations can either be inherited (Germline) and present in all individual cells or can be acquired and occur exclusively in the tumor cells (Somatic). Somatic mutations account for a significant portion of overall BRCA1 and BRCA2 aberrations. Loss of BRCA function due to frequent somatic aberrations likely deregulates HR pathway, and other pathways then come in to play, which are less precise and error prone, resulting in the accumulation of additional mutations and chromosomal instability in the cell, with subsequent malignant transformation. Homologous Recombination Deficiency therefore indicates an important loss of DNA repair function.

Pathogenic Variants (PVs) in BRCA1 and BRCA2 (BRCA1/2) are well known to be associated with increased lifetime risk for breast and ovarian cancer in women, and reliable risk estimates are also available and can be as high as 85% and 40% respectively. However, the association of BRCA1 and BRCA2 Pathogenic Variants with cancers other than female breast and ovarian cancers remain uncertain, and these associations have been based on studies with relatively small sample sizes, resulting in imprecise cancer risk estimates. It is therefore important that precise risk estimates are available, in order to optimize clinical management strategies and guidelines for cancer risk management in female and male BRCA1/2 carriers. The NCCN and other guidelines recommend breast and ovarian cancer screening for BRCA1/2 carriers, prostate cancer screening for BRCA2 carriers. Screening is also recommended for pancreatic cancer in BRCA1/2 carriers, but only in the presence of a positive family history of the disease.

The authors conducted this analysis to provide comprehensive and precise age-specific risk estimates of 22 cancers other than female breast and ovarian cancers associated with Pathogenic Variants in BRCA1 and BRCA2, for effective cancer risk management. The researchers used data from 3,184 BRCA1 families and 2,157 BRCA2 families in the Consortium of Investigators of Modifiers of BRCA1/2 (CIMBA), to estimate age-specific Relative Risk (RR) and absolute risks for 22 first primary cancer types, after adjusting for family ascertainment. CIMBA was formed by a collaborative group of researchers working on genetic modifiers of cancer risk in BRCA1 and BRCA2 mutation carriers and provides sufficient sample sizes to allow large scale studies, in order to reliably evaluate the effects of genetic modifiers.

BRCA1 Pathogenic Variants were associated with significantly increased risk of male breast cancer (RR = 4.30; 4.3 times increased risk), pancreatic cancer (RR = 2.36), and stomach cancer (RR = 2.17). Although associations of BRCA1 Pathogenic Variants with colorectal and gallbladder cancers were observed, the results were not robust in the sensitivity analyses performed.

BRCA2 Pathogenic Variants were associated with increased risk of male breast cancer (RR = 44.0), stomach cancer (RR = 3.69), pancreatic cancer (RR = 3.34) and prostate cancer (RR = 2.22). Female carriers had a higher risk of stomach cancer than male carriers (RR = 6.89 versus 2.76; P=0.04).

The absolute/cumulative risks to age 80 years ranged from 0.4% for male breast cancer to approximately 2.5% for pancreatic cancer for BRCA1 carriers and from approximately 2.5% for pancreatic cancer to 27% for prostate cancer for BRCA2 carriers. In the present study, previously suggested associations of BRCA1 Pathogenic Variants with risks of other genitourinary cancers and increased risk of bone, brain, blood, gallbladder cancers and melanoma for BRCA2 Pathogenic Variants, were not replicated.

It was concluded from this analysis that in addition to female breast and ovarian cancers, BRCA1 and BRCA2 Pathogenic Variants are associated with increased risks of male breast cancer, pancreatic cancer, stomach cancer, and prostate cancer, the later only with BRCA2 Pathogenic Variants , but are not associated with the risks of other previously suggested cancers. These findings provide age-specific cancer risk estimates and will allow for improved cancer risk assessment of male and female BRCA1/2 carriers.

Cancer Risks Associated With BRCA1 and BRCA2 Pathogenic Variants. Li S, Silvestri V, Leslie G, et al. DOI: 10.1200/JCO.21.02112 Journal of Clinical Oncology – published online before print January 25, 2022.

ENHERTU® in HER2-Mutant Non Small Cell Lung Cancer

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SUMMARY: The American Cancer Society estimates that for 2022, about 236,740 new cases of lung cancer will be diagnosed and 135,360 patients will die of the disease. Lung cancer is the leading cause of cancer-related mortality in the United States. Non-Small Cell Lung Cancer (NSCLC) accounts for approximately 85% of all lung cancers. Of the three main subtypes of NSCLC, 30% are Squamous Cell Carcinomas (SCC), 40% are Adenocarcinomas and 10% are Large Cell Carcinomas. With changes in the cigarette composition and decline in tobacco consumption over the past several decades, Adenocarcinoma now is the most frequent histologic subtype of lung cancer.

The HER or erbB family of receptors consist of HER1, HER2, HER3 and HER4. HER2 is a Tyrosine Kinase Receptor expressed on the surface of several tumor types including Breast, Gastric, Lung and Colorectal cancers. It is a growth-promoting protein and HER2 overexpression/HER2 gene amplification is often associated with aggressive disease and poor prognosis in certain tumor types. However, HER2 overexpression and gene amplification are associated with distinct molecular entities and have limited therapeutic value in lung cancer.

HER2 mutations unlike HER2 overexpression and gene amplification are oncogenic drivers, and have been detected in 2 to 3% of NSCLCs. They are more often detected in female patients and never-smokers, and almost exclusively in Adenocarcinomas. Majority of of HER2 mutations (80-90%) occur in exon 20, as either a duplication or an insertion of 12 nucleotides, resulting in the addition of four amino acids (YVMA) at codon 775 in the kinase domain. This distinct molecular entity is characterized by specific pathological and clinical behavior. These acquired HER2 gene mutations have been independently associated with cancer cell growth and poor prognosis. There are currently no therapies approved specifically for the treatment HER2 mutant NSCLC, and is therefore an unmet need.

ENHERTU® (Trastuzumab Deruxtecan) is an Antibody-Drug Conjugate (ADC) composed of a humanized monoclonal antibody specifically targeting HER2, with the amino acid sequence similar to HERCEPTIN® (Trastuzumab), attached to a potent cytotoxic Topoisomerase I inhibitor payload by a cleavable tetrapeptide-based linker. ENHERTU® has a favorable pharmacokinetic profile and the tetrapeptide-based linker is stable in the plasma and is selectively cleaved by cathepsins that are up-regulated in tumor cells. Unlike KADCYLA® (ado-Trastuzumab emtansine), which is also an Antibody-Drug Conjugate, ENHERTU® has a higher drug-to-antibody ratio (8 versus 4), the released payload easily crosses the cell membrane with resulting potent cytotoxic effect on neighboring tumor cells regardless of target expression, and the released cytotoxic agent (payload) has a short half-life, minimizing systemic exposure. ENHERTU® is approved in the US for the treatment of adult patients with unresectable or metastatic HER2 positive breast cancer who received two or more prior anti-HER2 based regimens, and locally advanced or metastatic HER2-positive Gastric or GastroEsophageal Junction adenocarcinoma who have received a prior Trastuzumab based regimen. Translational research demonstrated that HER2-mutant NSCLC may preferentially internalize the HER2 receptor Antibody-Drug Conjugate complex regardless of HER2 protein expression, and overcome resistance to other HER2-targeted agents.
Mechanism-of-Action-ENHERTU
DESTINY-Lung01 is a global, multicenter, open-label, two-cohort, Phase II study, conducted to evaluate the efficacy and safety of ENHERTU® in patients with HER2 mutant or HER2 overexpressing (defined as ImmunoHistoChemistry-IHC 3+ or IHC 2+), unresectable and metastatic non-squamous NSCLC. A total of 91 patients with HER2-mutant NSCLC were enrolled between May 30, 2018, and July 21, 2020 and treated with ENHERTU®. Patients who had previously been treated with a HER2 antibody or an Antibody-Drug Conjugate were ineligible for participation, but those who had previously received a HER2 Tyrosine Kinase Inhibitor such as Afatinib, Pyrotinib, or Poziotinib were eligible. The median patient age was 60 yrs and enrolled patients had a median of two prior lines of therapy, with majority of patients having received platinum-based chemotherapy (95%) and anti-PD-1 or PD-L1 treatment (66%). About 20% of patients received Docetaxel and 14% received HER TKIs. For the majority of patients (93%), HER2 mutations were located in the kinase domain. Patients received ENHERTU® 6.4 mg/kg every 3 weeks by intravenous infusion. The Primary endpoint was Objective Response Rate (ORR) as assessed by Independent Central Review. Secondary endpoints included Disease Control Rate (DCR), Duration of Response (DoR), Progression Free Survival (PFS), Overall Survival (OS) and Safety. At the time of data cutoff, the median duration of treatment was 6.9 months and treatment was ongoing for 16% of patients.

At a median follow up 13.1 months, the ORR was 55% and the median Duration of Response was 9.3 months. Responses were observed across different HER2 mutation subtypes. The median PFS was 8.2 months and the median OS was 17.8 months. The most common Grade 3 or higher drug-related Adverse Event was neutropenia noted in 19% of patients and adjudicated drug-related Interstitial Lung Disease occurred in 26% of patients and resulted in 2 deaths.

It was concluded that ENHERTU® demonstrated promising clinical activity, with a high Objective Response Rate and durable responses, in a heavily pretreated population of patients with HER2-mutated NSCLC.

Trastuzumab Deruxtecan in HER2-Mutant Non–Small-Cell Lung Cancer. Li BT, Smit EF, Goto Y, et al., for the DESTINY-Lung01 Trial Investigators. N Engl J Med 2022; 386:241-251

Sintilimab for Patients with Pretreated EGFR-Mutated Non Small Cell Lung Cancer

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SUMMARY: The American Cancer Society estimates that for 2021, about 235,760 new cases of lung cancer will be diagnosed and 131,880 patients will die of the disease. Lung cancer is the leading cause of cancer-related mortality in the United States. Non-Small Cell Lung Cancer (NSCLC) accounts for approximately 85% of all lung cancers. Of the three main subtypes of NSCLC, 30% are Squamous Cell Carcinomas (SCC), 40% are Adenocarcinomas and 10% are Large Cell Carcinomas. With changes in the cigarette composition and decline in tobacco consumption over the past several decades, Adenocarcinoma now is the most frequent histologic subtype of lung cancer.

Approximately 10-15% of Caucasian patients and 35-50% of Asian patients with Adenocarcinomas, harbor activating EGFR mutations and 90% of these mutations are either exon 19 deletions or L858R substitution mutation in exon 21. Patients with advanced EGFR-mutated NSCLC, following initial clinical response to first, second and third generation EGFR-TKIs therapies, will inevitably advance to a progressive disease course. These patients often receive platinum-based chemotherapy, with limited clinical benefit. Immune checkpoint inhibitors given alone have low efficacy in the treatment of patients with metastatic NSCLC with oncogenic-driven tumors. There is a highly unmet medical need for these patients with resistant disease.

Sintilimab is an immunoglobulin G4, anti-PD-1 monoclonal antibody, which binds to the PD-1 receptor and blocks its interaction with ligands PD-L1 and PD-L2. By doing so, it unleashes the tumor-specific effector T cells, and is thereby able to undo PD-1 pathway-mediated inhibition of the immune response.

ORIENT-31 is a prospective, randomized, double-blind, multi-center Phase III study, which evaluated Sintilimab, with or without a Bevacizumab biosimilar injection (IBI305), in combination with chemotherapy (Pemetrexed and Cisplatin), in patients with EGFR-mutated locally advanced or metastatic non-squamous NSCLC, who have progressed following EGFR TKI treatment. Patients were randomized in a 1:1:1 ratio to receive Sintilimab 200 mg IV plus Bevacizumab biosimilar 15 mg/kg IV combined with Pemetrexed 500 mg/m2 IV and Cisplatin 75 mg/m2 IV (Arm A), Sintilimab combined with Pemetrexed and Cisplatin (Arm B), or chemotherapy alone with Pemetrexed and Cisplatin (Arm C), all agents administered every 3 weeks for 4 cycles followed by maintenance treatment with Sintilimab plus Bevacizumab and Pemetrexed in Arm A, Sintilimab and Pemetrexed in Arm B, and Pemetrexed alone in Arm C. Treatment was continued until radiographic disease progression or unacceptable toxicity. Eligible patients included patients with disease progression following first or second generation EGFR TKI and confirmed as T790M negative, or T790M positive but further progressed on third generation EGFR TKI, or patients with disease progression following third generation EGFR TKI as first line treatment. The median age was 57 years, 36% of patients had brain metastasis, 64% of patients had received First or Second generation TKIs without T790M mutation, 28% had received First or Second generation TKIs and then a Third generation TKI for T790M mutation, and 8% patients received first line Third generation TKI. The target accrual was 480 patients and by the data cutoff date of the first interim analysis, 444 patients were enrolled. The Primary endpoint was Progression Free Survival (PFS) as assessed by an Independent Radiographic Review Committee (IRRC). Secondary endpoints included Overall Survival (OS), PFS as assessed by investigators, Objective Response Rate (ORR) and Safety. The median follow up at first interim analysis was 9.8 months.

Sintilimab plus Bevacizumab biosimilar in combination with chemotherapy (Arm A), demonstrated a statistically significant and clinically meaningful improvement in PFS, compared with Arm C (chemotherapy alone group). The median PFS was 6.9 months in Arm A, and 4.3 months in Arm C (HR=0.46; P<0.0001). Additionally, the key Secondary endpoints of ORR and Duration of Response (DOR) were improved in Arm A compared with Arm C, and the results of PFS, ORR and DOR assessed by the investigator were consistent with the results assessed by IRRC. The prespecified PFS futility analysis that compares Arm A to Arm B (Sintilimab and chemotherapy group) did not cross futility stopping boundary. The PFS data of Arm B versus Arm C were immature.

The authors concluded that in this first prospective, double-blind, Phase III study among patients with EGFR mutated NSCLC who had progressed after EGFR TKIs, this quadruple regimen of Sintilimab plus Bevacizumab biosimilar in combination with chemotherapy, significantly improved Progression Free Survival, compared with chemotherapy alone.

VP9-2021: ORIENT-31: Phase III study of sintilimab with or without IBI305 plus chemotherapy in patients with EGFR mutated nonsquamous NSCLC who progressed after EGFR-TKI therapy. Lu S, Wu L, Jian H, et al. Published:November 19, 2021DOI:https://doi.org/10.1016/j.annonc.2021.10.007.

PSMA Targeted Therapy Improves Overall Survival in Metastatic Prostate Cancer

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SUMMARY: Prostate cancer is the most common cancer in American men with the exclusion of skin cancer, and 1 in 8 men will be diagnosed with prostate cancer during their lifetime. It is estimated that in the United States, about 248,530 new cases of prostate cancer will be diagnosed in 2021 and 34,130 men will die of the disease.

The development and progression of prostate cancer is driven by androgens. Androgen Deprivation Therapy (ADT) or testosterone suppression has therefore been the cornerstone of treatment of advanced prostate cancer, and is the first treatment intervention. Approximately 10-20% of patients with advanced Prostate cancer will progress to Castration Resistant Prostate Cancer (CRPC) within five years during ADT, and over 80% of these patients will have metastatic disease at the time of CRPC diagnosis. Among those patients without metastases at CRPC diagnosis, 33% are likely to develop metastases within two years. Progression to Castration Resistant Prostate Cancer (CRPC) often manifests itself with a rising PSA (Prostate Specific Antigen) and the estimated mean survival of patients with CRPC is 9-36 months, and there is therefore an unmet need for new effective therapies.

Prostate-Specific Membrane Antigen (PSMA) is a type II cell membrane glycoprotein that is selectively expressed in prostate cells, with high levels of expression in prostatic adenocarcinoma. PSMA is a therefore an excellent target for molecular imaging and therapeutics, due to its high specificity for prostate cancer.

Lu-177-PSMA-617 is a radiopharmaceutical that targets PSMA. It is comprised of Lutetium-177, linked to the ligand PSMA-617, a small molecule designed to bind with high affinity to PSMA. Radioligand therapy with Lu-177-PSMA-617 targets PSMA and releases its payload of lethal beta radiation into the prostate cancer cell. The antitumor activity and safety of Lu-177-PSMA-617 have been established previously in a Phase II study (Lancet Oncol. 2018;19:825-833).

VISION is an international, randomized, open-label Phase III study in which the benefit of Lu-177-PSMA-617 was evaluated in men with PSMA-positive mCRPC, previously treated with second generation Androgen Receptor signaling pathway inhibitor (XTANDI®-Enzalutamide or ZYTIGA®-Abiraterone acetate), and 1 or 2 taxane chemotherapy regimens. In this trial, 831 patients were randomized 2:1 to receive Lu-177-PSMA-617, 7.4 GBq every 6 weeks for 6 cycles plus Standard of Care as determined by the treating physician (N=551), or Standard of Care only (N=280). Both treatment groups were well balanced and this trial excluded patients treated with XOFIGO® (Radium-223). Enrolled patients had a castrate level or serum/plasma testosterone of lower than 50 ng/dL, and PET imaging with 68 Ga-PSMA-11 was used to determine PSMA positivity by central review. The Primary endpoints were radiographic Progression Free Survival (rPFS) by Independent Central Review (ICR) and Overall Survival (OS). Secondary endpoints included Objective Response Rate (ORR), Disease Control Rate (DCR), and time to first Symptomatic Skeletal Event (SSE). The median study follow up was 20.9 months.

Lu-177-PSMA-617 plus Standard of Care significantly improved rPFS by 60%, compared to Standard of Care alone (median rPFS 8.7 versus 3.4 months, HR=0.40; P<0.001). The median OS was also significantly improved by 38% with Lu-177-PSMA-617 plus Standard of Care compared to Standard of Care alone (median OS 15.3 versus 11.3 months, HR=0.62; P<0.001). All key secondary endpoints including Objective Response Rate, Disease Control Rate, and time to first Symptomatic Skeletal Event were statistically significant, and in favor of Lu-177-PSMA-617 plus Standard of Care.

It was concluded that radioligand therapy with Lutetium-177–PSMA-617 significantly improved radiographic Progression Free Survival and Overall Survival when added to Standard of Care, compared with Standard of Care alone, in men with PSMA-positive metastatic Castration Resistant Prostate Cancer.

Lutetium-177-PSMA-617 for Metastatic Castration-Resistant Prostate Cancer. Sartor O, de Bono J, Chi KN, et al. N Engl J Med 2021; 385:1091-1103.

FDA Approves EXKIVITY® for Metastatic Non Small Cell Lung Cancer with EGFR exon 20 Insertion Mutations

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SUMMARY: The FDA on September 15, 2021, granted accelerated approval to EXKIVITY® (Mobocertinib), for adult patients with locally advanced or metastatic Non Small Cell Lung Cancer (NSCLC) with Epidermal Growth Factor Receptor (EGFR) exon 20 insertion mutations, as detected by an FDA-approved test, whose disease has progressed on or after Platinum-based chemotherapy. The FDA also approved the Oncomine Dx Target Test as a companion diagnostic device to select patients with the above mutations for EXKIVITY® treatment.

The American Cancer Society estimates that for 2021, about 235,760 new cases of lung cancer will be diagnosed and 131,880 patients will die of the disease. Lung cancer is the leading cause of cancer-related mortality in the United States. Non-Small Cell Lung Cancer (NSCLC) accounts for approximately 85% of all lung cancers. Of the three main subtypes of NSCLC, 30% are Squamous Cell Carcinomas (SCC), 40% are Adenocarcinomas and 10% are Large Cell Carcinomas. With changes in the cigarette composition and decline in tobacco consumption over the past several decades, Adenocarcinoma now is the most frequent histologic subtype of lung cancer.

Approximately 10-15% of Caucasian patients and 35-50% of Asian patients with Adenocarcinomas, harbor activating EGFR mutations and 90% of these mutations are either exon 19 deletions or L858R substitution mutation in exon 21. EGFR exon 20 insertion mutations are the third most common after L858R and exon 19 deletions, and occur in about 2-3% patients with NSCLC, and are insensitive to EGFR Tyrosine Kinase Inhibitors (TKIs) due to an altered conformation of the kinase active site. Next-Generation sequencing provides an alternative to Polymerase Chain Reaction (PCR)-based tests, which fail to identify 50% or more of exon 20 insertion mutations. Patients with EGFR exon 20 insertion mutations have a 5 year Overall Survival (OS) of 8% in the frontline setting, compared to an OS of 19% for patients with EGFR exon 19 deletions or L858R mutations. There is therefore a clinically unmet need for this patient group, as there are no approved targeted therapies available and platinum-doublet chemotherapy remains the standard of care for these patients.

EXKIVITY® is a novel oral EGFR TKI, that was designed to address the unmet need in patients with EGFR exon 20 insertion mutant positive NSCLC. EXKIVITY® was designed to potently inhibit oncogenic variants containing activating mutations in exon 20, with selectivity over Wild Type EGFR.

The present FDA approval of EXKIVITY® was based on an international, non-randomized, open-label, multicohort clinical trial (NCT02716116) which included patients with locally advanced or metastatic NSCLC with EGFR exon 20 insertion mutations. This trial was conducted in three parts- Dose escalation or Part 1, to determine the safety profile of EXKIVITY®, Expansion phase or Part 2, to evaluate the antitumor activity of EXKIVITY® in seven histologically and molecularly defined cohorts, and Extension phase or Part 3, to evaluate efficacy of EXKIVITY® in patients with locally advanced or metastatic NSCLC whose tumors harbor EGFR exon 20 insertion mutations, and who have been previously treated.

So, this 3-part, multicenter study has dose-escalation/expansion and extension (EXCLAIM) cohorts. Patients with EGFR exon 20 insertion positive metastatic NSCLC, with ECOG status 0-1, and one or more prior lines of therapy for locally advanced/metastatic disease, received EXKIVITY® 160 mg orally daily, until disease progression or intolerable toxicity. Efficacy was evaluated in 114 patients whose disease had progressed on or after Platinum-based chemotherapy. Among these platinum pretreated patients, the median age was 60 years, 66% were female, 60% were Asian, and 59% had 2 or more prior systemic therapies. The main efficacy outcome measures were confirmed Objective Response Rate (ORR) assessed by blinded Independent Review Committee (IRC) and Duration of Response.

At a median follow up of 14.2 months, the ORR was 28%, with a median Duration of Response of 17.5 months. The median Progression Free Survival was 7.3 months and the median Overall Survival was 24 months. Clinically meaningful improvements were observed for dyspnea, coughing, chest pain, and these benefits were evident by cycle 2, and maintained throughout treatment. The most common adverse reactions were rash, nausea, stomatitis, vomiting, diarrhea, decreased appetite, paronychia, fatigue, dry skin, and musculoskeletal pain.

It was concluded that EXKIVITY® is the first and only oral therapy specifically designed to target EGFR exon 20 insertions, and the present FDA approval is an important addition, designed for this patient population.

Mobocertinib (TAK-788) in EGFR exon 20 insertion (ex20ins)+ metastatic NSCLC (mNSCLC): additional results from platinum-pretreated patients (pts) and EXCLAIM cohort of phase 1/2 study. Ramalingam SS, Zhou C, Kim TM, et al. J Clin Oncol. 2021;39(suppl 15):9014. DOI:10.1200/JCO.2021.39.15_suppl.9014.

Maintenance RUBRACA® in Patients with Advanced Pancreatic Cancer with a Pathogenic Germline or Somatic Variant in BRCA1, BRCA2, or PALB2

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SUMMARY: The American Cancer Society estimates that for 2021, about 60,430 people will be diagnosed with pancreatic cancer and about 48,220 people will die of the disease. Pancreatic cancer is the fourth most common cause of cancer-related deaths in the United States and Western Europe. Unfortunately, unlike other malignancies, very little progress has been made and outcome for patients with advanced pancreatic cancer has been dismal, with a 5-year survival rate for metastatic pancreatic cancer of approximately 2%. Pancreatic cancer has surpassed breast cancer as the third leading cause of cancer death in the United States and is on track to surpass colorectal cancer, to move to the second leading cause of cancer related deaths in the United States around 2021.

DNA damage is a common occurrence in daily life by UV light, ionizing radiation, replication errors, chemical agents, etc. This can result in single and double strand breaks in the DNA structure which must be repaired for cell survival. The two vital pathways for DNA repair in a normal cell are BRCA1/BRCA2 and PARP. BRCA1 and BRCA2 genes recognize and repair double strand DNA breaks via Homologous Recombination Repair (HRR) pathway. Homologous Recombination is a type of genetic recombination, and is a DNA repair pathway utilized by cells to accurately repair DNA double-stranded breaks during the S and G2 phases of the cell cycle, and thereby maintain genomic integrity. Homologous Recombination Deficiency (HRD) is noted following mutation of genes involved in HR repair pathway. At least 15 genes are involved in the Homologous Recombination Repair (HRR) pathway including BRCA1, BRCA2, PALB2, CHEK2 and ATM genes. BRCA1 and BRCA2 are tumor suppressor genes located on chromosome 17 and chromosome 13 respectively and functional BRCA proteins repair damaged DNA, and play an important role in maintaining cellular genetic integrity. They regulate cell growth and prevent abnormal cell division and development of malignancy. Mutations in these genes predispose an individual to develop malignant tumors. It is well established that the presence of BRCA1 and BRCA2 mutations can significantly increase the lifetime risk for developing breast and ovarian cancer, as high as 85% and 40% respectively. BRCA1/2 mutations have been detected in 4-7% of patients with pancreatic cancer, with a 2-6 fold increase in risk, associated with these mutations. These patients tend to be younger. Among pancreatic cancer patients with Ashkenazi Jewish ancestry, the prevalence of BRCA1/2 mutations is 6-19%, with mutations more common for BRCA2. NCCN guideline recommends that germline testing should be considered for all patients with pancreatic cancer and is especially recommended for those with a personal history of cancer, family history or clinical suspicion of a family history of pancreatic cancer. Approximately 10% of pancreatic cancer cases have a familial component. When hereditary cancer syndrome is suspected in patients with pancreatic cancer, genetic counseling should be considered.

BRCA mutations can either be inherited (Germline) and present in all individual cells or can be acquired and occur exclusively in the tumor cells (Somatic). Somatic mutations account for a significant portion of overall BRCA1 and BRCA2 aberrations. Loss of BRCA function due to frequent somatic aberrations likely deregulates HR pathway, and other pathways then come in to play, which are less precise and error prone, resulting in the accumulation of additional mutations and chromosomal instability in the cell, with subsequent malignant transformation. Homologous Recombination Deficiency therefore indicates an important loss of DNA repair function.

The PARP (Poly ADP Ribose Polymerase), family of enzymes include, PARP1 and PARP2, and is a related enzymatic pathway that repairs single strand breaks in DNA. In a BRCA mutant, the cancer cell relies solely on PARP pathway for DNA repair to survive. PARP inhibitors trap PARP onto DNA at sites of single-strand breaks, preventing their repair and generating double-strand breaks that cannot be repaired accurately in tumors harboring defects in Homologous Recombination Repair pathway genes, such as BRCA1 or BRCA2 mutations, and this leads to cumulative DNA damage and tumor cell death.

LYNPARZA® (Olaparib) is a PARP inhibitor and is presently approved as maintenance therapy for patients with advanced pancreatic cancer demonstrating a germline BRCA1 or BRCA2 pathogenic variant. However, previously published studies have demonstrated the benefit of PARP inhibitors in breast, prostate and ovarian cancer patients, beyond germline BRCA pathogenic variants. Further, there is an unmet need to expand the group of patients with pancreatic cancer who may benefit from therapy with a PARP inhibitor, beyond those with germline BRCA pathogenic variants.

This investigator-initiated, single-arm Phase II study was conducted to assess the role of oral, small molecule PARP inhibitor RUBRACA® (Rucaparib), as maintenance therapy in advanced pancreatic cancer with germline or somatic pathogenic variants in BRCA1, BRCA2, or PALB2 genes. This study enrolled 46 patients with advanced pancreatic cancer with germline or somatic pathogenic variants in BRCA1, BRCA2, or PALB2, and had received at least 16 weeks of platinum-based chemotherapy without evidence of platinum resistance, which was defined as growing tumors, new lesions, or a steadily rising tumor marker during or within 8 weeks of platinum therapy. The median age was 62 years, approximately 17% had germline BRCA1, 64% had germline BRCA2, 14% had germline PALB2 and 5% had somatic BRCA2 pathogenic variants. Majority of patients (95%) had metastatic disease and 5% had locally advanced disease. Ashkenazi Jewish founder mutation was found in 24% of patients. The Primary end point was Progression Free Survival (PFS) at 6 months (PFS). Secondary end points included Safety, Objective Response Rate (ORR), Disease Control Rate, Duration of Response, and Overall Survival.

The PFS at 6 months was 59.5% and the PFS at 12 months was 54.8%. The median PFS was 13.1 months and median Overall Survival was 23.5 months. The ORR in those with measurable disease was 42%, and the Disease Control Rate was 67%. The median Duration of Response was 17.3 months. These responses were noted across all germline and somatic pathogenic variants in BRCA1, BRCA2, and PALB2 genes, and no new safety signals were noted.

It was concluded from this study that maintenance RUBRACA® is a safe and effective therapy for platinum-sensitive, advanced pancreatic cancer patients, with a pathogenic variant in BRCA1, BRCA2, or PALB2. The authors added that the finding of efficacy in patients with germline PALB2 and somatic BRCA2 pathogenic variants, expands the population of patients likely to benefit from PARP inhibitors, beyond those with germline BRCA1 and BRCA2 pathogenic variants.

Phase II Study of Maintenance Rucaparib in Patients With Platinum-Sensitive Advanced Pancreatic Cancer and a Pathogenic Germline or Somatic Variant in BRCA1, BRCA2, or PALB2. Reiss KA, Mick R, O’Hara MH, et al. J Clin Oncol. 2021;39:2497-2505.