Shepherd, Lois E.

CCTG CLC.2/Alliance A041202 demonstrated superior progression-free survival at 2 years with ibrutinib alone (87%; HR 0.39) or ibrutinib-rituximab (IR 88%; HR 0.38) compared to chemo-immunotherapy with bendamustine-rituximab (BR 74%) in treatment-naïve patients (pts) with chronic lymphocytic leukemia (CLL) who were 65 or older (Woyach NEJM 2018). We hypothesized that ibrutinib-based therapies would be more costly than BR but that costs would be offset by less toxicity and improved quality of life (QOL). We completed a prospective trial-based economic analysis to study the direct medical costs and quality-adjusted benefit associated with ibrutinib-based therapies compared to BR in the Canadian (CDN) subset of patients enrolled in CLC.2/Alliance 041202. All CDN pts were invited to participate in the companion analysis. Health utilities were collected using the EuroQOL EQ-5D and calculated using CDN population valuations (Bansback PLOS One 2012). Resource utilization forms were administered to collect off-protocol health care encounters. The planned analysis was a cost-utility analysis from the perspective of a public healthcare system, examining the costs and outcomes (quality-adjusted life years or QALYs) of ibrutinib-based therapy compared to BR. Unit costs were applied to resource data based on publicly available provincial/national databases; all costs were expressed in 2019 US dollars (1 CDN = 0.75 US dollar). Total and disaggregated direct medical costs are presented descriptively. Mean survival was calculated using the restricted mean survival method from randomization to the study time-horizon of 24 months; derived utilities were used to calculate QALYs. A discount rate for costs and benefits (r=0.05) was applied. The analysis was based on estimation (with bootstrapping) of an incremental cost-effectiveness ratio (ICER) and/or direct medical costs. A total of 55 pts were enrolled; two pts who did not receive any treatment were censored at day 1 and 3 after randomization and excluded from analysis. Of the 53 analysed, pt demographics were well balanced between treatments and were reflective of the entire population: mean age was 71.6 (SD 6.34) in pts receiving ibrutinib alone (n=17), 72.2 (SD 3.85) in pts receiving IR (n=18), and 71.7 (SD 4.1) in pts receiving BR (n=18). A total of 3 pts, one in each arm, had 17p deletion. Progression-free survival at 2 years for CDN pts was 94% (95% CI 65-99%) for ibrutinib, 100% (95% CI 100-100%) for IR, and 72% (95% CI 45-87%) for BR (Figure 1). At 24 months, 1 pt on the BR arm had crossed over to ibrutinib (as per protocol); there was no overall survival difference between the three arms. On-protocol costs (including protocol treatment, ambulatory care, and imaging) and off-protocol costs (including hospitalizations, concomitant medications, and ambulatory care) are highlighted in Figure 2. On-protocol costs were higher for pts receiving ibrutinib (mean $142,001 USD; SD 48,417) and IR ($164,931; SD 46,208) compared to BR ($38,509; SD 10,351), driven by higher drug acquisition costs associated with ibrutinib (list price $6422 for 420mg/30 days). In contrast, off-protocol costs were modestly higher for pts on BR (mean $3050; SD 3812) compared to the ibrutinib ($2460; SD 3863) or IR ($2890; SD 4206); hospitalizations were the key off-protocol cost drivers and were highest for pts on IR and BR. Overall mean costs over the 2-year time horizon were $144,461 (SD 47,910) for pts on ibrutinib, $167,820 (SD 46,830) for pts on IR, and $41,560 (SD 11,849) for pts on BR. Discounted QALYs were similar between the three treatment arms: 1.66 (0.16) for ibrutinib alone, 1.65 (0.24) for IR, and 1.66 (0.17) for BR. Given the similar quality-adjusted survival between arms at the time of this analysis, a formal ICER was not calculated. Direct medical costs are substantially higher for pts receiving continuous ibrutinib-based therapies, compared to chemo-immunotherapy of fixed duration, in frontline CLL management; the key cost driver is the cost of ibrutinib. The PFS benefit with ibrutinib-based therapy has not translated into an advantage in quality-adjusted survival to date; further follow-up may be required to demonstrate any cost or QOL benefits associated with fewer progression events for those on ibrutinib. Support: U10CA180821, U10CA180882; U10CA180863 and #704970 CCTG. https://acknowledgments.alliancefound.org ClinicalTrials.gov: NCT01886872 Figure Disclosures Owen: AbbVie, F. Hoffmann-La Roche, Janssen, Astrazeneca, Merck, Servier, Novartis, Teva: Honoraria. Lam:Roche: Honoraria, Speakers Bureau; Janssen: Honoraria, Speakers Bureau. Crump:Servier: Consultancy; Kite/Gilead: Consultancy; Roche: Consultancy. Sperlich:Lundbeck Canada: Honoraria. Woyach:Pharmacyclics, Janssen, Morphosys, Karyopharm, Verastem, Abbvie, Lox: Research Funding; Janssen, Pharmacyclics, AstraZeneca, Abbvie, Arqule: Consultancy; Pharmacyclics LLC, an AbbVie Company, AbbVie, Janssen, AstraZeneca, ArQule: Honoraria. Prica:astra zeneca: Honoraria; seattle genetics: Honoraria; Gilead: Honoraria. Hay:Roche: Research Funding; Janssen: Research Funding.

Abstract Purpose: To determine genetic variants that could differentiate aromatase inhibitors (AIs) efficacy in early stage breast cancer. Experimental Design: We performed a stratified cox-proportional hazards analysis utilizing stratification factors and other covariates examining Breast Cancer Free Interval (BCFI) SNP-treatment interaction in Caucasian patients entered on the MA.27 trial. This analysis involved 4465 patients (2226 on anastrozole and 2239 on exemestane arm) including 245 (121 on anastrozole and 124 events on exemestane arm) with a breast event. Preclinical laboratory studies included luciferase activity, chromatin immunoprecipitation (ChIP) assay, and cell migration assays. Results: We identified 887 SNPs with a p-value <1E-4 that could differentiate anastrozole from exemestane efficacy. We next used GTEx databases to determine whether these SNPs might be cis-eQTLs with nearby genes, and found that 95 SNPs were eQTL with 14 genes. Functional validation of SNP effect in these 14 genes on response to anastrozole and exemestane revealed that 3 SNPs showed genotype-dependent differences between anastrozole and exemestane. Two of the three SNPs, rs1877193 and rs6735923 located upstream of LY75 gene, were associated with higher LY75 gene expression. Our drug-SNP interaction GWAS showed that both SNPs were associated with better BCFI for exemestane compared to anastrozole (HR= 0.447, 0.458). The SNP rs62293499 located downstream of the GPR160 gene was also associated with better BCFI for exemestane compared to anastrozole (HR=0.433). Interestingly, all 3 SNPs were associated with worse outcome (shorter BCFI) in anastrozole treated patients (HR=1.39~1.58), but with longer BCFI in the exemestane treated patients (HR=0.58~0.71) based on our GWAS results in MA.27 trial. However, all 3 SNPs showed no association with BCFI if the two treatment arms, anastrozole and exemestane, were combined (HR=0.92~1.08). Consistently, cells with Ly75 or GPR160 SNP variant genotypes were more sensitive to exemestane compared to anastrozole. Mechanistically, the 3 SNPs regulated estrogen receptor-dependant LY75 and GPR160 expression. LY75 suppression induced epithelial-to-mesenchymal transition (EMT) in breast cancer cell lines, accompanied by increased migratory capacity in vitro. LY75 knockdown also resulted in predominant downregulation of functional pathways such as cell proliferation, while pathways associated with mesenchymal stimulation were generally increased. GPR160 knockdown also resulted in downregulation of cell proliferation pathways. Conclusions: This SNP genotype and AI treatment interaction clinical study revealed unique genetic variants that differentiate anastrozole and exemestane efficacy. The signals were lost in the GWAS analysis when anastrozole and exemestane were combined. Preclinical laboratory studies revealed novel functions of LY75 and GPR160 in breast cancer. These findings represent potential steps towards individualized AI therapy. Citation Format: Junmei Cairns, James N. Ingle, Krishna R. Kalari, Lois E. Shepherd, Matthew J. Ellis, Paul E. Goss, Poulami Barman, Erin E. Carlson, Matthew P. Goetz, Richard M. Weinshilboum, Liewei Wang. The interaction between SNP genotype and aromatase inhibitor treatment response in early breast cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr LB-103.

Aromatase inhibitors (AIs) reduce breast cancer recurrence and prolong survival, but up to 30% of patients exhibit recurrence. Using a genome-wide association study of patients entered on MA.27, a phase III randomized trial of anastrozole versus exemestane, we identified a single nucleotide polymorphism (SNP) in CUB And Sushi multiple domains 1 ( CSMD1) associated with breast cancer–free interval, with the variant allele associated with fewer distant recurrences. Mechanistically, CSMD1 regulates CYP19 expression in an SNP- and drug-dependent fashion, and this regulation is different among 3 AIs: anastrozole, exemestane, and letrozole. Overexpression of CSMD1 sensitized AI-resistant cells to anastrozole but not to the other 2 AIs. The SNP in CSMD1 that was associated with increased CSMD1 and CYP19 expression levels increased anastrozole sensitivity, but not letrozole or exemestane sensitivity. Anastrozole degrades estrogen receptor α (ERα), especially in the presence of estradiol (E2). ER + breast cancer organoids and AI- or fulvestrant-resistant breast cancer cells were more sensitive to anastrozole plus E2 than to AI alone. Our findings suggest that the CSMD1 SNP might help to predict AI response, and anastrozole plus E2 serves as a potential new therapeutic strategy for patients with AI- or fulvestrant-resistant breast cancers.

Objectives Based on our previous findings that postmenopausal women with estrone (E1) and estradiol (E2) concentrations at or above 1.3 pg/ml and 0.5 pg/ml, respectively, after 6 months of adjuvant anastrozole therapy had a three-fold risk of recurrence, we aimed to identify a single-nucleotide polymorphism (SNP)-based model that would predict elevated E1 and E2 and then validate it in an independent dataset. Patients and methods The test set consisted of 322 women from the M3 study and the validation set consisted of 152 patients from MA.27. All patients were treated with adjuvant anastrozole, had on-anastrozole E1 and E2 concentrations and genome-wide genotyping. Results SNPs were identified from the M3 genome-wide association study. The best model to predict the E1-E2 phenotype with high balanced accuracy was a support vector machine model using clinical factors plus 46 SNPs. We did not have an independent cohort that is similar to the M3 study with clinical, E1-E2 phenotypes and genotype data to test our model. Hence, we chose a nested matched case-control cohort (MA.27 study) for testing. Our E1-E2 model was not validated but we found the MA.27 validation cohort was both clinically and genomically different. Conclusions We identified a SNP-based model that had excellent performance characteristics for predicting the phenotype of elevated E1 and E2 in women treated with anastrozole. This model was not validated in an independent dataset but that dataset was clinically and genomically substantially different. The model will need validation in a prospective study.

Abstract Background Metformin has been associated with lower breast cancer (BC) risk and improved outcomes in observational studies. Multiple biologic mechanisms have been proposed, including a recent report of altered sex hormones. We evaluated the effect of metformin on sex hormones in MA.32, a phase III trial of nondiabetic BC subjects who were randomly assigned to metformin or placebo. Methods We studied the subgroup of postmenopausal hormone receptor-negative BC subjects not receiving endocrine treatment who provided fasting blood at baseline and at 6 months after being randomly assigned. Sex hormone-binding globulin, bioavailable testosterone, and estradiol levels were assayed using electrochemiluminescence immunoassay. Change from baseline to 6 months between study arms was compared using Wilcoxon sum rank tests and regression models. Results 312 women were eligible (141 metformin vs 171 placebo); the majority of subjects in each arm had T1/2, N0, HER2-negative BC and had received (neo)adjuvant chemotherapy. Mean age was 58.1 (SD=6.9) vs 57.5 (SD=7.9) years, mean body mass index (BMI) was 27.3 (SD=5.5) vs 28.9 (SD=6.4) kg/m2 for metformin vs placebo, respectively. Median estradiol decreased between baseline and 6 months on metformin vs placebo (−5.7 vs 0 pmol/L; P < .001) in univariable analysis and after controlling for baseline BMI and BMI change (P < .001). There was no change in sex hormone-binding globulin or bioavailable testosterone. Conclusion Metformin lowered estradiol levels, independent of BMI. This observation suggests a new metformin effect that has potential relevance to estrogen sensitive cancers.

Abstract Introduction. The NCIC CTG is conducting phase II testing to establish the tolerability and estimate the efficacy of combining lenalidomide (L) + melphalan (M) over multiple cycles for previously untreated patients with multiple myeloma who are ineligible for stem cell transplantation. We report the data from the preliminary safety phase of this trial. Methods. The MY.11 trial was initially designed as a randomized phase II test of M 9 mg/m2 given on days 1–4 (M9) plus either L 10 mg (L10) or 20 mg given on days 1–21 of a 28 day cycle. Primary prophylaxis with G-CSF was not included, but use of G-CSF for established neutropenia was permitted; our intent was to determine dose levels that could be given independently of G-CSF. A dose attenuation schedule was developed for neutropenia and/or thrombocytopenia that was severe and occurred during the administration of L or was persistent and caused a delay in the next treatment cycle. A hematologic dose limiting toxicity (H-DLT) was defined as the need for 2 dose attenuations of L or 1 dose attenuation of M. Prior to the randomized phase of the trial, a safety run-in phase testing M9+L10 in 6 patients was planned; closure of this arm was to occur if, during the first 3 treatment cycles, there were ≥ 3 H-DLTs or any non-hematologic serious adverse event (SAE) judged to be treatment related. Four of the planned 6 patients were entered; during their first 3 treatment cycles, each experienced a H-DLT and one died from sepsis. The study was therefore amended with the intent to conduct a randomized phase II test of M 4 mg/m2 days 1–4 plus L 15 mg days 1–21 (M4L15) and M 6 mg/m2 days 1–4 plus L 10 mg days 1–21 (M6L10). Prior to the randomized phase of testing, each regimen was tested in non-randomized safety run-ins that included 6 patients per arm. The same parameters as above for study arm closure were applied. If the M6L10 arm was closed, the trial would proceed to test M 5 mg/m2 days 1–4 and L 10 mg days 1–21 (M5L10). Results. Six patients were enrolled to M4L15: during their first 3 treatment cycles, 4 patients experienced H-DLTs related to severe or persistent grade 3–4 neutropenia and one other patient experienced an SAE related to hallucinations and multiple constitutional complaints. This arm was therefore closed to accrual. Six patients were enrolled to M6L10: during their first 3 treatment cycles, 3 patients experienced H-DLTs related to severe or persistent grade 3–4 neutropenia. One of these patients was hospitalized with pulmonary edema and another with febrile neutropenia. This arm was therefore closed and the MY.11 trial amended to proceed as a single-arm phase II testing M5L10. Conclusion. Although M + L holds promise as an effective combination for previously untreated myeloma patients, the regimen is associated with considerable myelosuppression. The efficacy of the combination when given at tolerable doses remains to be established.

1033 Background: MA.32 investigates effects of Metformin vs. Placebo, in addition to standard care, on invasive disease free survival and other outcomes. Metformin may improve obesity and metabolic factors [insulin, glucose, leptin, C-reactive protein (CRP)] that have been associated with poor BC outcomes. Maintaining blinding of investigators to outcomes, we conducted a planned, DSMB approved, analysis of the effect of Metformin vs. Placebo on weight and metabolic factors at 6 months, including examination of interactions with baseline body mass index (BMI), in the first 498 subjects with paired fasting plasma samples. Methods: 498 non-diabetic subjects with T1-3, N0-3, M0 BC meeting defined entry criteria who had completed surgery and adjuvant chemo (if given) provided fasting blood samples at randomization and 6 months (while on study drug). Glucose was measured locally; blood was aliquoted, frozen and stored at -80°C then shipped to NCIC CTG (Kingston, Canada). Paired plasma aliquots were shipped to Mount Sinai Hospital (Toronto, Canada) for analysis of Insulin (Dako), hsCRP (Roche Elecsys) and leptin (Luminex). Statistical analysis used the Wilcoxon signed rank test. Results: Mean age was 52.4 ±9.2 years. Arms were balanced for ER/PgR (63% pos), BMI, prior adjuvant chemo (89%), T and N status, grade, mastectomy/lumpectomy and radiation. Conclusions: Metformin significantly improved weight, insulin, glucose, leptin and CRP at 6 months. Effects did not vary by baseline BMI. Funded by: NIH, CCSRI, CBCF, BCRF, Apotex Canada (drug & placebo - in kind). Clinical trial information: NCT01101438. [Table: see text]

564 Background: Our group previously examined if baseline patient/tumor characteristics, or prior treatment affected cause of death in MA.17, a placebo controlled extended adjuvant trial of the aromatase inhibitor (AI) letrozole. We now examine factor effects on all cause mortality in MA.27. Methods: MA.27 was an adjuvant phase III superiority trial of 5 yrs of exemestane vs anastrozole, in ER+ postmenopausal breast cancer accrued between 2003 and 2008; event free survival was similar. We examined by intention-to-treat, the multivariate time-to-breast cancer-specific (BrCa), cardiovascular (Cardio), and other causes (OT) of death with log-normal survival analysis adjusted by treatment and stratification factors (lymph node status, adjuvant chemotherapy, celecoxib, aspirin, and trastuzumab). We tested whether factors were associated with 1) all cause mortality, and if so, 2) cause-specific mortality. We also fit step-wise forward cause-specific adjusted models. Results: 7,576 women (median age 64.1 years; 5417 (71.5%) <70 yrs and 2159 (28.5%) >70 yrs) were enrolled and followed for a median of 4.1 yrs. The 432 deaths comprised: 187 (43.3%) BrCa, 66 (15.3%) Cardiovascular, and 179 (41.4%) OT MA.27 therapy was not associated with mortality (p=0.84). Five baseline factors were differentially associated with cause of death. Older age was associated with greater BrCa (p=0.03), Cardio (p<0.001), and OT (p<0.001) mortality. Pre-existing cardiovascular history led to worse Cardio mortality (p<0.001). Worse ECOG performance status led to worse OT death (p<0.001). T1 tumors were associated with less BrCa mortality (p<0.001). PgR+ tumors were also associated with less BrCa mortality (p<0.001). There were fewer BrCa deaths with Node –ve disease (p<0.001), ER+ tumors (p=0.001) and without adjuvant chemotherapy (p=0.005); there was worse Cardio mortality (p=0.01) with receipt of trastuzumab; worse OT (p=0.03) for non-whites, and without adjuvant radiotherapy (p=0.003). Conclusions: 56.7% of deaths in MA.27 patients were non-breast cancer related. We showed baseline patient and tumor characteristics, and prior treatment differentially affected cause of death. Clinical trial information: NCT00066573.

550 Background: 5187 postmenopausal women were originally randomized to NCIC CTG MA.17 to receive letrozole (LET) or placebo (PLAC) after 5 years of tamoxifen. The hazard ratio (HR) for disease-free survival (DFS) was 0.58 (0.450.76, p=0.00004) after a median follow-up of 30 months (mo). The trial was unblinded in October 2003 after the first interim analysis. Women randomized to PLAC were offered LET at the time of unblinding. The goal of this analysis was to determine whether women switching from PLAC to LET benefit in terms of disease outcome and to evaluate treatment related toxicities. Methods: LET and PLAC-LET have been compared to PLAC, based on the hazard ratio and adjusting for baseline patient and disease variables including, among others, tumor size, nodal status and prior adjuvant chemotherapy. Results: Information about their follow-up treatment after unblinding was available on 2268 women originally assigned to PLAC and who were free of recurrence and alive at the time of unblinding. Among them, 1655 crossed over from PLAC to LET while 613 elected no treatment. With 54 mo f/up the HR for DFS was 0.31 (0.18, 0.55: p<0.0001) favoring patients who crossed over to LET compared to those who stayed on no treatment. The treatment switch was well tolerated with no significant difference in bone fractures or cardiovascular events. An updated analysis of DFS, DDFS and OS by nodal and tumor receptor status, prior chemotherapy, menopausal status at the start of tamoxifen, and duration of prior tamoxifen therapy will be presented at the meeting. Conclusion: Women with hormone dependent breast cancer prescribed LET after a prolonged delay from completing tamoxifen experienced a significant improvement in outcome (DFS, DDFS, OS) and should be considered for this therapy. [Table: see text]

Abstract Purpose: To determine if the degree of estrogen suppression with aromatase inhibitors (AI: anastrozole, exemestane, letrozole) is associated with efficacy in early-stage breast cancer, and to examine for differences in the mechanism of action between the three AIs. Experimental Design: Matched case–control studies [247 matched sets from MA.27 (anastrozole vs. exemestane) and PreFace (letrozole) trials] were undertaken to assess whether estrone (E1) or estradiol (E2) concentrations after 6 months of adjuvant therapy were associated with risk of an early breast cancer event (EBCE). Preclinical laboratory studies included luciferase activity, cell proliferation, radio-labeled ligand estrogen receptor binding, surface plasmon resonance ligand receptor binding, and nuclear magnetic resonance assays. Results: Women with E1 ≥1.3 pg/mL and E2 ≥0.5 pg/mL after 6 months of AI treatment had a 2.2-fold increase in risk (P = 0.0005) of an EBCE, and in the anastrozole subgroup, the increase in risk of an EBCE was 3.0-fold (P = 0.001). Preclinical laboratory studies examined mechanisms of action in addition to aromatase inhibition and showed that only anastrozole could directly bind to estrogen receptor α (ERα), activate estrogen response element-dependent transcription, and stimulate growth of an aromatase-deficient CYP19A1−/− T47D breast cancer cell line. Conclusions: This matched case–control clinical study revealed that levels of estrone and estradiol above identified thresholds after 6 months of adjuvant anastrozole treatment were associated with increased risk of an EBCE. Preclinical laboratory studies revealed that anastrozole, but not exemestane or letrozole, is a ligand for ERα. These findings represent potential steps towards individualized anastrozole therapy.