Author: RR

SUMMARY: PD 0332991 is an oral,  selective inhibitor of CDK4/6 kinases. This agent interrupts cellular DNA synthesis  by inhibiting the progression of the cell cycle from G1 to S phase and thus prevents tumor cell growth. The results presented, includes the pooled data from the study of  2 cohorts of patients. Both groups included postmenopausal women with advanced breast cancer and  ER positive, HER2 negative tumors. Patients were randomized 1:1 to receive either letrozole (FEMARA®)  along with PD 0332991 or FEMARA® alone. Group 1 enrolled 66 patients and Group 2 enrolled 99 patients. Group 2 patient tumors  were also  evaluated  for the biomarkers cyclinD1 amplification and/or loss of p16, by FISH analysis. For both these study groups, the primary endpoint was Progression Free Survival (PFS). Secondary endpoints included response rates, overall survival, safety, and biomarker correlates. Data from the pooled analysis which included 165 women from both the groups demonstrated a median PFS of 26.1 months for the combination compared to 7.5 months with FEMARA® alone. This represented a 63% reduction in risk of progression  (hazard ratio =0.37; P < 001). The most common adverse events noted in the combination group included uncomplicated neutropenia, anemia, and fatigue. Biomarkers expression (cyclinD1 amplification and/or loss of p16) had no impact on outcomes suggesting  that the biomarker for PD0332991 may be the estrogen receptor itself rather than CDK4/6 kinases. Finn RS, Crown JP, Lang I, et al. CTRC-AACR San Antonio Breast Cancer Symposium 2012; Abstract S1-6.

SUMMARY:There is not much data on the effectiveness and safety of Zoledronic acid (ZOMETA®) beyond 2 years. Two studies one from Belgium and the other from Japan shed some light on this issue. In the prospective multicenter Belgian trial, 108 women with breast cancer prior to enrollment had received at least 24 months of therapy with ZOMETA® infusions given every 3 to 4 weeks and 21% had received at least 48 months of therapy. They were followed for 18 months and monitored for Skeletal Related Events (SRE’s), Osteo Necrosis of the Jaw bone (ONJ), renal failure and hypocalcemia. During this follow up period, SRE’s were low and 83% of the women were free of SRE’s. ONJ was seen in 7 patients (4.5%). The rate of ONJ however rose to 11% after any invasive dental procedure. The risk of renal failure was low but increased to 12%when the dose of ZOMETA® was not adjusted for renal function. The Japanese study was a retrospective analysis of 83 patients who had been treated with ZOMETA® for at least 24 months (median 33 months). SRE’s were low and the frequency of ONJ was 3.6% compared to 2.4% for those patients who had been ZOMETA® for shorter periods. Both these studies demonstrated that longer duration of therapy with ZOMETA® resulted in increased rate of ONJ. Therefore, particular attention should be paid to prevent this complication by adhering to proper dental hygiene and avoiding dental trauma and extractions. Van den Wyngaert T, Delforge M, Doyen C, et al. and Suzuki Y, Saito Y, Ogiya R, et al. CTRC-AACR San Antonio Breast Cancer Symposium 2012; Poster P3-13-01 and P3-13-02.

SUMMARY: Fulvestrant (FASOLODEX®) is an Estrogen Receptor (ER) antagonist and downregulates the cellular levels of ER in a dose-dependent manner. The CONFIRM trial is a phase III study in which postmenopausal women with estrogen receptor (ER) positive advanced breast cancer, who had progressed after prior endocrine therapy, were randomized to be treated with either FASLODEX® 500 mg (n=362) or FASLODEX® 250 mg (n=374) every 28 days. The primary end point for this study was Progression Free Survival (PFS). In the primary analysis, FASLODEX® 500 mg was associated with a statistically significant increase in PFS compared with FASLODEX® 250 mg. Even though there was a trend towards improved overall survival (OS) with the higher dose, this was not statistically significant. In the updated second survival analysis presented at this symposium, the median OS trend prevailed with FASLODEX® 500mg compared with FASLODEX® 250mg, given every 28 days (26.4 months vs 22.3 months, P=0.16). This translated into a 4 month increase in median overall survival and a 19% reduction in the risk of death. The authors concluded that the higher dose of FASLODEX® may indeed confer some survival benefit to this patient subsets. Di Leo A, Jerusalem G, Petruzelka L, et al. CTRC-AACR San Antonio Breast Cancer Symposium; 2012; Abstract S1-4.

SUMMARY: Cognitive impairment in patients with breast cancer has been frequently attributed to chemotherapy (Chemo Brain) without any data supporting this hypothesis. Utilizing functional magnetic resonance imaging, brain function was tested while the patients were performing a working memory task in the scanner, before adjuvant treatment and then one month after adjuvant treatment. Sixty six breast cancer patients with Stages 0-IIIA were studied and their cognitive function was compared with 32 healthy controls. Patients on treatment were receiving either an anthracyline-based adjuvant chemotherapy regimen (n = 29) or radiotherapy (n = 37). Patients self-reported on levels of cognitive functioning and fatigue after each imaging study. Pretreatment brain imaging revealed decreased functioning in the frontal lobe of the brain (responsible for memory and cognition), compared to the controls and this cognitive impairment was most severe in patients awaiting chemotherapy, whereas the radiotherapy group fell between the pre-chemotherapy and control group. Of Interest, the decreased functioning in the frontal lobe area before treatment predicted the severity of fatigue. Further, those with greater fatigue experienced greater cognitive impairment over time. The authors concluded that the cognitive problems are probably related to worry and fatigue prior to treatment intervention rather than the treatment itself. They recommend identifying patients at risk and early intervention. Cimprich B, Hayes DF, Askren MK, et al. CTRC-AACR San Antonio Breast Cancer Symposium, 2012; Abstract S6-3.

SUMMARY: Historically, adjuvant treatment with tamoxifen beyond five years has not been recommended, as the benefit of tamoxifen beyond five years was unknown but there was an increased risk of endometrial cancer. (Tamoxifen Treatment for Breast Cancer and Risk of Endometrial Cancer: A Case-Control Study, J Natl Cancer Inst 2005; 97: 375-384). The ATLAS trial has now shed some light on the duration of tamoxifen treatment. In this study, 6846 women with ER positive breast cancer were enrolled between 1996 and 2005 and following five years of adjuvant tamoxifen were randomized to five additional years of tamoxifen or observation. Women who continued on tamoxifen had a 25% lower recurrence rate and 29% lower breast cancer mortality rate compared with women who stopped tamoxifen after five years. This significant benefit was seen in the second decade after diagnosis with little benefit seen in the 5-9 year period after diagnosis. There was a higher cumulative risk of death from endometrial cancer for those who continued tamoxifen beyond 5 years compared to those who did not (0.4% vs 0.2%). It appears that the reduction in breast cancer deaths outweigh the risk of endometrial cancer and other adverse events associated with longer duration of tamoxifen use. This new information will help physicians make appropriate treatment recommendations for those patients on adjuvant tamoxifen. Davis C, Hongchao P, Godwin J, et al. CTRC-AACR San Antonio Breast Cancer Symposium, 2012; Abstract S1-2.

SUMMARY: Approximately 5% to 15% of all breast cancer patients present with local and/or regional recurrences. The role of adjuvant chemotherapy after resection of an isolated recurrence of breast cancer is unknown. To address this, in the CALOR trial, 162 patients with recurrent tumors underwent surgery and were then randomized to receive either four cycles of a multidrug chemotherapy regimen of investigator’s choice (n=85) or observation (n=77). The median age was 56 years. The treatment groups were well balanced and 68% and 58% of patients in the observation and treatment arms respectively received prior adjuvant chemotherapy. The median time to recurrence was 5 years in the treatment group and 6 years in the observation group. The primary end point was disease free survival (DFS). The 5-year DFS rate for the chemotherapy group and observation group was 69% vs 57% respectively. This translated into a relative risk reduction of 41% (hazard ratio [HR], 0.59; P = 0.045). The 5-year overall survival rate between the chemotherapy group and observation group was 88% vs 76% with a 59% reduction in the relative risk for death for patients treated with chemotherapy (HR, 0.41; P = 0.02). In patients with ER-negative tumors, the 5-year DFS was 67% in the treatment arm versus 35% in the control group (HR = 0.32; P = 0.007). This data supports the role of chemotherapy for patients with completely resected isolated locoregional recurrences of breast cancer. Aebi S, Gelber S, Láng I, et al. Presented at: CTRC-AACR San Antonio Breast Cancer Symposium, 2012. Abstract S3-2.