Category: Precision Oncology

BRAFTOVI®, MEKTOVI® and ERBITUX® Triplet Therapy for Patients with BRAF V600E-Mutant Metastatic Colorectal Cancer

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SUMMARY: ColoRectal Cancer (CRC) is the third most common cancer diagnosed in both men and women in the United States. The American Cancer Society estimates that approximately 145,600 new cases of CRC will be diagnosed in the United States in 2019 and about 51,020 patients are expected to die of the disease. The lifetime risk of developing CRC is about 1 in 23. Advanced colon cancer is often incurable and standard chemotherapy when combined with anti EGFR (Epidermal Growth Factor Receptor) targeted monoclonal antibodies such as VECTIBIX® (Panitumumab) and ERBITUX® (Cetuximab) as well as anti VEGF agent AVASTIN® (Bevacizumab), have demonstrated improvement in Progression Free Survival (PFS) and Overall Survival (OS). The benefit with anti EGFR agents however is only demonstrable in patients with metastatic CRC (mCRC), whose tumors do not harbor KRAS mutations in codons 12 and 13 of exon 2 (KRAS Wild Type). It is now also clear that even among the KRAS Wild Type patient group about 15-20% have other rare mutations such as NRAS and BRAF mutations, which confer resistance to anti EGFR agents. Patients with stage IV colorectal cancer are now routinely analyzed for extended RAS and BRAF mutations. KRAS mutations are predictive of resistance to EGFR targeted therapy. Approximately 8-15% of all metastatic CRC tumors present with BRAF V600E mutations and BRAF V600E is recognized as a marker of poor prognosis in this patient group. These patients tend to have aggressive disease with a higher rate of peritoneal metastasis and do not respond well to standard treatment intervention. Approximately 20% of the BRAF-mutated population in the metastatic setting has MSI-High tumors, but MSI-High status does not confer protection to this patient group.BRAF-and-MEK-Inhibition-in-MAPK-Pathway

The Mitogen-Activated Protein Kinase pathway (MAPK pathway) is an important signaling pathway which enables the cell to respond to external stimuli. This pathway plays a dual role, regulating cytokine production and participating in cytokine dependent signaling cascade. The MAPK pathway of interest is the RAS-RAF-MEK-ERK pathway. The RAF family of kinases includes ARAF, BRAF and CRAF signaling molecules. BRAF is a very important intermediary of the RAS-RAF-MEK-ERK pathway. The BRAF V600E mutations results in constitutive activation of the MAP kinase pathway. Inhibiting BRAF can transiently reduce MAP kinase signaling. However, this can result in feedback upregulation of EGFR signaling pathway, which can then reactivate the MAP kinase pathway. This aberrant signaling can be blocked by dual inhibition of both BRAF and EGFR. However, BRAF V600E-mutated CRC is inherently less sensitive to BRAF inhibition than melanoma.

The FDA approved BRAFTOVI® (Encorafenib) and MEKTOVI® (Binimetinib) in combination for the first-line treatment of patients with BRAF V600-mutant melanoma, in June 2018. In a recent Phase II study among previously treated patients with BRAF V600E-mutant mCRC, treatment with a combination of BRAFTOVI® plus ERBITUX® resulted in an Objective Response Rate (ORR) of 24%, PFS of 4.2 months, and OS of 9.3 months. These results were significantly better than the standard of care, as well as other BRAF, MEK, and EGFR-inhibitor triplet combinations. Preclinical data suggests that BRAFTOVI® has target binding characteristics that differ from other BRAF inhibitors such as ZELBORAF® (Vemurafenib) and TAFINLAR® (Dabrafenib), with a prolonged target dissociation half-life and higher potency. This may explain the superior efficacy of BRAFTOVI® over other BRAF inhibitors in BRAF V600E-mutated CRC. These encouraging results with the BRAFTOVI® plus ERBITUX® doublet led to the initiation of the Phase III BEACON CRC study.

The BEACON Colorectal Cancer trial is an open-label, randomized, three-arm, Phase III study in which the efficacy and safety of BRAFTOVI® plus ERBITUX® with or without MEKTOVI® was compared with the investigators’ choice of ERBITUX® combined with either Irinotecan or Fluorouracil, Folinic acid, and Irinotecan, in patients with BRAF V600E-mutant mCRC whose disease has progressed after one or two prior regimens. At the time BEACON CRC was initiated, the triplet combination of MEKTOVI®, BRAFTOVI®, and ERBITUX® had not been clinically evaluated. The authors therefore conducted a Safety Lead-In (SLI) to determine the Safety, tolerability, and preliminary efficacy of this triplet combination at the same doses planned for the randomized portion of the trial.

The randomized portion of the trial was ongoing at the time of this analysis. The BEACON trial included patients with mCRC whose tumor tissue was positive for the presence of BRAF V600E mutation. Majority of the patients had right-sided disease as is characteristic of BRAF V600E-mutant mCRC, with a high frequency of nodal and peritoneal metastasis. Liver however, was the most frequent site of metastasis. Enrolled patients must have had progressive disease on one, but no more than two prior treatment regimens, in the metastatic setting. Enrolled patients received BRAFTOVI® 300 mg PO daily plus MEKTOVI® 45 mg PO BID along with ERBITUX® 400 mg/m2 IV, followed by 250 mg/m2 IV weekly every 28 days. The Safety Lead-In was initiated before the randomized portion of the BEACON trial and included 30 patients with disease characteristics and treatment schedule as described above. The Primary end point was Safety, including the incidence of dose-limiting toxicities. Efficacy end points included Overall Response Rate, Progression Free Survival, and Overall Survival.

The median follow up was 18.2 months, and the median time on study drug was 7.9 months. The confirmed Overall Response Rate was 48%, median Duration of Response was 5.5 months, median Progression Free Survival was 8.0 months, and median Overall Survival was 15.3 months. Approximately 79% of responding patients achieved a response within 2 months. The most common adverse events were nausea, diarrhea, fatigue and dermatitis. Approximately 6% of patients experienced serous retinopathy without loss of visual acuity.

It was concluded that in this Safety Lead-In, the combination regimen of BRAFTOVI®, MEKTOVI® and ERBITUX® resulted in promising results compared with available therapies, among patients with previously treated BRAF V600E-mutant mCRC, and if confirmed in the randomized portion of the trial, could become the new standard of care in this patient group. Binimetinib, Encorafenib, and Cetuximab Triplet Therapy for Patients With BRAF V600E–Mutant Metastatic Colorectal Cancer: Safety Lead-In Results From the Phase III BEACON Colorectal Cancer Study. Van Cutsem E, Huijberts S, Grothey A, et al. Journal of Clinical Oncology 2019; 37:1460-1469.

Five-Year Outcomes with TAFINLAR® plus MEKINIST® in Metastatic Melanoma

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SUMMARY: It is estimated that in the US, approximately 96,480 new cases of Melanoma will be diagnosed in 2019 and about 7,230 patients are expected to die of the disease. The incidence of Melanoma has been on the rise for the past three decades. Surgical resection with a curative intent is the standard of care for patients with early stage Melanoma, with a 5-year survival rate of 98% for stage I disease and 90% for stage II disease. Patients with locally advanced or metastatic Melanoma historically have had poor outcomes. With the development and availability of immune checkpoint inhibitors and BRAF and MEK inhibitors, this patient group now has significantly improved outcomes. In treatment naïve patients receiving anti-PD-1 therapies such as KEYTRUDA® (Pembrolizumab) or OPDIVO® (Nivolumab) in phase 3 trials, the Progression Free Survival (PFS) rates have ranged from 27-31%, with an Overall Survival (OS) rate of 46% at 4 years. The 5-year OS among patients receiving KEYTRUDA® was 43%, and in those treated with a combination of OPDIVO® plus YERVOY® (Ipilimumab), 4-year PFS and OS rates were 37% and 53%, respectively.BRAF-and-MEK-Inhibition-in-MAPK-Pathway

The Mitogen-Activated Protein Kinase pathway (MAPK pathway) is an important signaling pathway which enables the cell to respond to external stimuli. This pathway plays a dual role, regulating cytokine production and participating in cytokine dependent signaling cascade. The MAPK pathway of interest is the RAS-RAF-MEK-ERK pathway. The RAF family of kinases includes ARAF, BRAF and CRAF signaling molecules. BRAF is a very important intermediary of the RAS-RAF-MEK-ERK pathway. BRAF mutations have been detected in 6-8% of all malignancies. The most common BRAF mutation in Melanoma is at the V600E/K site and is detected in approximately 50% of Melanomas, and result in constitutive activation of the MAPK pathway.

TAFINLAR® (Dabrafenib), is a selective oral BRAF inhibitor and MEKINIST® (Trametinib) is a potent and selective inhibitor of MEK gene, which is downstream from RAF in the MAPK pathway. It has been well established that patients who have unresectable or metastatic Melanoma with a BRAFV600E or V600K mutation have prolonged PFS and OS when treated with a combination of BRAF and MEK inhibitors. However, long-term 4 and 5-year clinical outcomes in these patient’s have not been reported.

Two randomized Phase III trials helped address this issue. COMBI-d involved 423 patients randomized to TAFINLAR® plus MEKINIST® (N=211) or to TAFINLAR® plus placebo (N=212). In COMBO-v, 704 patients were randomized to TAFINLAR® plus MEKINIST® (N=352) or to single-agent ZELBORAF® (Vemurafenib; N=352). In a previously published pooled analysis of patients treated in the COMBI-d and COMBI-v trials, 3-year PFS and OS were 23% and 44% respectively. Further, there was a significant association between several baseline factors such as performance status, age, sex, number of organ sites with metastasis, serum LDH level and both PFS as well as OS.

In this review, the researchers analyzed pooled long term survival data from two randomized Phase III COMBI-d and COMBI-v trials, which involved previously untreated, unresectable or metastatic Melanoma patients, with BRAFV600E or V600K mutation, who had received BRAF inhibitor TAFINLAR® 150 mg orally twice daily along with a MEK inhibitor MEKINIST® 2 mg orally once daily. These two trials evaluated the efficacy and safety of TAFINLAR® plus MEKINIST®, as compared with BRAF inhibitor monotherapy. The long term, 5-year survival data from these two trials was reported, along with clinical characteristics of the patients who derived long-term benefit from this treatment. The Primary end points in the COMBI-d and COMBI-v trials were PFS and OS, respectively. The median patient age in these trials was 55 years, 3% of patients had nonmetastatic disease and two-thirds had M1c metastatic disease.

A total of 563 patients (211 in the COMBI-d trial and 352 in the COMBI-v trial) were randomly assigned to receive TAFINLAR® plus MEKINIST®. The PFS rates were 21% at 4 years and 19% at 5 years. The OS rates were 37% at 4 years and 34% at 5 years. The 5-year OS rate was 71% among patients who had a Complete Response and 55% among those who had a normal Lactate Dehydrogenase level plus fewer than three metastatic organ sites at baseline.

It was concluded that first-line treatment with TAFINLAR® plus MEKINIST® led to long-term benefit in approximately one third of the patients who had unresectable or metastatic Melanoma with a BRAF V600E or V600K mutation. The authors added that this is the largest data set and longest follow-up in this patient population treated with BRAF and MEK inhibitors. Five-Year Outcomes with Dabrafenib plus Trametinib in Metastatic Melanoma. Robert C, Grob JJ, Stroyakovskiy D, et al. June 4, 2019. DOI: 10.1056/NEJMoa1904059

FDA Approves First PI3K Inhibitor, PIQRAY®, for Breast Cancer

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SUMMARY: The FDA on May 24, 2019 approved PIQRAY® (Alpelisib) in combination with FASLODEX® (Fulvestrant), to treat postmenopausal women and men, with Hormone Receptor (HR) positive, Human Epidermal growth factor Receptor 2 (HER2) negative, PIK3CA-mutated, advanced or metastatic breast cancer (as detected by an FDA-approved test), following progression on or after an endocrine-based regimen. The FDA also approved the companion diagnostic test, therascreen PIK3CA RGQ PCR Kit, to detect the PIK3CA mutation in a tissue and/or a liquid biopsy. Patients who are negative by the therascreen test using the liquid biopsy should undergo tumor biopsy for PIK3CA mutation testing. Breast cancer is the most common cancer among women in the US and about 1 in 8 women (12%) will develop invasive breast cancer during their lifetime. Approximately 268,600 new cases of female breast cancer will be diagnosed in 2019 and about 41,760 women will die of the disease. About 70% of breast tumors express Estrogen Receptors and/or Progesterone Receptors and these patients are often treated with anti-estrogen therapy as first line treatment. However, resistance to hormonal therapy occurs in a majority of the patients.Alpelisib - Mechanism-of-Action

The PhosphoInositide 3-Kinase (PI3K) pathway is an intracellular signaling pathway important in the regulation of cancer cell proliferation and metastasis. PI3K is a lipid kinase and has four distinct isoforms – alpha, beta, gamma and delta, which play a unique role in the survival of different tumor types and establishment of supportive tumor microenvironments. The alpha and beta isoforms are expressed in a wide variety of tissues whereas the gamma and delta isoforms are primarily expressed in hematopoietic cells such as B and T cells. The PI3K alpha isoform is particularly important in breast cancer and plays an important role in tumorigenesis, supporting tumor angiogenesis and stromal interactions, making this a viable target. PIK3CA is an oncogene that codes for the alpha isoform of PI3K, (PI3Kα), more specifically for the alpha isoform of p110. The PI3k pathway is the most frequently altered pathway in human cancers including breast cancer, and has been implicated in disease progression in a significant number of patients with breast cancer. Activation of the PI3K pathway in breast cancer has been associated with resistance to endocrine therapy and disease progression. Approximately 40% of patients with Hormone Receptor positive (HR+), HER2 negative breast cancers, harbor activating mutations in the PIK3CA isoform of PI3K, which is the most common mutation in HR+ breast cancer. Patients with advanced breast cancer harboring PIK3CA mutations typically have a poor prognosis. This provides a strong rationale for targeting the PI3K pathway in breast cancer.

PIQRAY® is an oral, alpha-specific PI3K inhibitor that specifically inhibits PIK3 in the PI3K/AKT kinase signaling pathway. Further, it was shown in preclinical studies that cancer cells with PIK3CA mutations are more sensitive to PIQRAY® than those without the mutation, across a broad range of tumor types. SOLAR-1 clinical trial, which was conducted to test this hypothesis, became the basis for this FDA approval.

SOLAR-1 is a global, double-blind, placebo-controlled, randomized phase III trial, which studied the benefit of PIQRAY® in combination with FASLODEX® (Fulvestrant) among postmenopausal women and men with PIK3CA-mutated HR+/HER2 negative advanced or metastatic breast cancer, who had progressed on or following prior Aromatase Inhibitor (AI) treatment with or without a Cyclin-Dependent Kinase (CDK) 4/6 inhibitor. In this study, 572 patients were randomized in a 1:1 ratio to receive PIQRAY® 300 mg orally daily or placebo once daily, in combination with FASLODEX® 500mg IM on days 1 and 15 of the first cycle and day 1 of each subsequent 28-day cycle. Patients were stratified based on visceral metastases and prior CDK4/6 inhibitor treatment. A total of 341 patients had PIK3CA mutations upon testing of the tumor tissue with 169 patients receiving the PIQRAY® combination and 172 patients receiving FASLODEX® alone. Enrolled patients had received one or more prior lines of hormonal therapy, but no chemotherapy for advanced breast cancer. They had not previously received FASLODEX® or any PI3K, Akt or mTOR inhibitor, and were not on concurrent anticancer therapy. Approximately half of the patients in each treatment group had lung or liver metastases and 6% had received prior CDK4/6 inhibitor therapy. The Primary endpoint was Progression Free Survival (PFS) for patients with the PIK3CA mutation. Secondary endpoints included Overall Survival (OS), Overall Response Rate (ORR), Clinical Benefit Rate, Health-Related Quality of Life, Efficacy in PIK3CA non-mutant cohort, Safety and Tolerability.

The Primary endpoint was met and at a median follow up of 20 months, the PFS was nearly twice as long in patients with PIK3CA mutations randomized to PIQRAY® plus FASLODEX® compared to the placebo plus FASLODEX® group. The median PFS was 11.0 months in the PIQRAY® group compared to 5.7 months in the placebo group (HR=0.65; P=0.00065). In patients with measurable, PIK3CA-mutated advanced breast cancer (N=262), the Overall Response Rate was 36% for the PIQRAY® plus FASLODEX® group versus 16% for placebo plus FASLODEX® group (P=0.0002). There was no significant PFS benefit noted in the PIK3CA-nonmutant patient group receiving PIQRAY® plus FASLODEX® The most frequent toxicities with PIQRAY® were hyperglycemia which could be managed with Metformin, nausea, decreased appetite and skin rash.

It was concluded that PIQRAY® given along with FASLODEX® significantly improved Progression Free Survival compared to Placebo plus FASLODEX® with manageable toxicities. The authors commented that this is the first study to show statistically significant, clinically meaningful PFS improvement with an alpha-specific PI3K inhibitor in PIK3CA-mutated HR+, HER2 negative advanced breast cancer, highlighting the importance of clinical genomics in advanced breast cancer. PIQRAY® is also the first novel drug approved under the Real-Time Oncology Review pilot program. It however remains unclear whether PIQRAY® should be incorporated into the current treatment paradigm upfront, along with endocrine therapy and a CDK 4/6 inhibitor, or sequentially following disease progression on a combination of endocrine therapy and a CDK 4/6 inhibitor. Alpelisib (ALP) + fulvestrant (FUL) for advanced breast cancer (ABC): results of the phase 3 SOLAR-1 trial. André F, Ciruelos EM, Rubovszky G, et al. Presented during the Presidential Symposium 1 at: 2018 ESMO Congress; October 19-23; Munich, Germany. Abstract LBA3_PR.

Liquid Biopsy Accurate, Reliable and Rapid in Identifying Biomarker Mutations in Newly Diagnosed Advanced Lung Cancer

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SUMMARY: The American Cancer Society estimates that for 2019 about 228,150 new cases of lung cancer will be diagnosed and 142,670 patients will die of the disease. Non Small Cell Lung Cancer (NSCLC) accounts for approximately 85% of all lung cancers. Patients with newly diagnosed metastatic NSCLC are often tested for guideline-recommended genomic biomarkers which include both predictive biomarker mutations such as EGFR, ALK, ROS1, BRAF, RET, MET, ERBB2, as well as prognostic biomarker mutation such as KRAS.

The application of precision medicine with targeted therapy requires detection of molecular abnormalities in a tissue biopsy specimen. However, if testing is not done with a comprehensive assay, such as Next-Generation Sequencing and is done in successive steps one test after another, tissue sample can be depleted, with not enough tissue left for testing of all biomarkers. Following progression or recurrence, archived biopsy specimens may not be helpful, as it is important to identify additional mutations in the tumor at the time of recurrence or progression, in order to plan appropriate therapy. Further, recurrent tumors may be inaccessible for a safe biopsy procedure or the clinical condition of the patient may not permit a repeat biopsy. Additionally, the biopsy itself may be subject to sampling error due to tumor heterogeneity. Genotyping circulating cell-free tumor DNA (cfDNA) in the plasma can potentially overcome the shortcomings of repeat biopsies and tissue genotyping, allowing the detection of many more targetable gene mutations, thus resulting in better evaluation of the tumor genome landscape.

The Noninvasive versus Invasive Lung Evaluation (NILE) trial is a prospective, multicenter study conducted to demonstrate the noninferiority of comprehensive cell-free DNA (cfDNA) relative to standard-of-care traditional tissue genotyping tests, to identify guideline-recommended genomic biomarkers, in patients with metastatic NSCLC. The authors in this study enrolled 282 newly diagnosed patients at 28 North American centers, with previously untreated, nonsquamous, metastatic NSCLC undergoing standard-of-care tissue genotyping. Enrolled patients submitted a pretreatment blood sample for cfDNA analysis utilizing a CLIA-certified comprehensive 73-gene next generation sequencing panel (Guardant360®). Over 80% of the enrolled patients were white and over 50% were female.

The liquid biopsy utilizing Guardant360®, detected biomarker mutations at a rate similar to standard-of-care tissue genotyping tests, in the enrolled patients, meeting the Primary study objective. At least one of the guideline-recommended genomic biomarkers was detected in 60 patients (21.3%) using tissue-based tests and in 77 patients (27.3%) by cfDNA utilizing Guardant360® (P<0.0001). The detection rate was increased by 48% when Guardant360® was utilized for cfDNA analysis and this included those with negative, not assessed, or Quantity Not Sufficient (QNS) results in tissue. In addition, the Positive Predictive Value was 100% for cfDNA versus tissue genotyping, for FDA approved targets such as EGFR, ALK, ROS1, and BRAF mutations. There are agents already approved by the FDA to treat this patient population. The median turnaround time was significantly lower for cfDNA, compared to tissue genotyping (9 versus 15 days; P <0.0001).

The authors concluded that in this largest cfDNA study among patients with previously untreated advanced NSCLC, cfDNA successfully detected seven biomarker mutations noninvasively, significantly faster than tissue genotype testing, and was also able to rescue biomarker mutation positive patients who had non-diagnostic tissue results. They added that the findings in this study confirms similar findings from Europe and demonstrates the clinical utility of cfDNA in newly diagnosed metastatic NSCLC. Clinical utility of comprehensive cell-free DNA (cfDNA) analysis to identify genomic biomarkers in newly diagnosed metastatic non-small cell lung cancer (mNSCLC). Leighl N, Page RD, Raymond VM, et al. Presented at: AACR Annual Meeting April 2, 2019; Philadelphia, USA.

Anaplastic Lymphoma Kinase Inhibition in Non Small Cell Lung Cancer

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SUMMARY:The therapeutic target of interest is an aberrant fusion gene, EML4-ALK. EML4 (echinoderm microtubule-associated protein-like 4) – ALK (anaplastic lymphoma kinase) is a fusion-type oncoprotein and is tyrosine kinase. This oncoprotein/tyrosine kinase is found in 2-7% of all Non Small Cell Lung Cancers (NSCLC) and is generated due to an inversion in the short arm of chromosome 2. This oncoprotein is more prevalent in patients with adenocarcinoma who have little or no exposure to tobacco. Tyrosine kinases normally play an important role in cellular proliferation and differentiation. However with point mutations, translocation/rearrangement and amplifications of their respective genes, these tyrosine kinases can potentially cause malignancy. Such is the case with mutations or translocations of the Anaplastic Lymphoma Kinase gene (ALK). In an article published in the October 28, 2010 issue of the NEJM, Crizotinib an oral small molecule tyrosine kinase inhibitor of ALK tyrosine kinase resulted in an overall response rate of 57% in patients who had progressed on prior therapies. Stable disease was noted in 33% of the patients. This is remarkable considering that the response rates in this patient population treated with second line chemotherapy is around 10-15%. As we move forward, it is very likely that genotyping patients and tailoring therapy accordingly, will become standard practice. N Engl J Med 2010; 363:1693-1703