Sledge, George W.

Abstract Background: A recent exploratory subgroup analysis pooling data from over 1000 patients (pts) in MONARCH 2 (final analysis) and MONARCH 3 (interim analysis) demonstrated that pts with clinical characteristics that predict for worse outcome (e.g. liver metastases, progesterone receptor [PgR]-negative status, high-grade tumors) received the largest benefit from the addition of abemaciclib to endocrine therapy (ET). There is also interest in determining the extent to which abemaciclib improves progression-free survival (PFS) in pts with favorable prognostic factors (e.g. bone-only disease, long treatment-free interval [TFI]). Here we present an update of the subgroup analyses of the MONARCH 3 study using data from the preplanned final PFS analysis. Methods: Enrollment criteria and study designs were previously described (Sledge et al. J Clin Oncol. 2017; Goetz et al. J Clin Oncol. 2017). An exploratory pooled analysis was conducted using data from MONARCH 2 (NCT02107703) and the MONARCH 3 (NCT02246621) preplanned final PFS analysis to identify significant prognostic factors regardless of therapy received. Using the updated MONARCH 3 data, PFS and objective response rate (ORR) (in pts with measurable disease) were examined within the prognostic subgroups that had been previously identified as being statistically significant. Additionally, subpopulation treatment effect pattern plot (STEPP) methodology was used to evaluate the association between TFI following adjuvant ET and outcomes of NSAI alone or with abemaciclib. Results: Assessment of clinical factors from MONARCH 2 and MONARCH 3 (final PFS data) confirmed that the following factors remained significantly prognostic regardless of treatment received: bone-only disease, liver metastases, tumor grade, PgR status, and ECOG performance status. In MONARCH 3, prognosis was poor in pts with liver metastases, PgR-negative tumors, and high-grade tumors. While all subpopulations benefited from the addition of abemaciclib to ET regardless of prognosis, pts with these three poor prognostic factors received substantial benefit from abemaciclib, with PFS hazard ratios (HR) ranging from 0.4 to 0.5 and with differential improvement in ORR typically >30%. Furthermore, STEPP analysis of TFI (on the MONARCH 3 pts who had received adjuvant ET) demonstrated that pts who had a shorter TFI had a worse prognosis and received relatively greater benefit from abemaciclib plus NSAI than did pts with a longer TFI. Patients with bone-only disease or a long TFI also received benefit from abemaciclib, but to a relatively lesser extent (HR ranging from approximately 0.6 to 0.8). Conclusions: This exploratory analysis of the preplanned final PFS data from MONARCH 3 confirms previous findings that pts with poor prognostic factors may receive relatively greater benefit from the addition of abemaciclib to ET. Citation Format: Joyce O'Shaughnessy, Matthew P. Goetz, George W. Sledge, Miguel Martin, Yong Lin, Tammy Forrester, Ian C. Smith, Angelo Di Leo, Stephen Johnston. The benefit of abemaciclib in prognostic subgroups: An update to the pooled analysis of MONARCH 2 and 3 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr CT099.

PurposeBevacizumab improves progression-free survival but not overall survival in patients with metastatic breast cancer. E5103 tested the effect of bevacizumab in the adjuvant setting in patients with human epidermal growth factor receptor 2–negative disease.Patients and MethodsPatients were assigned 1:2:2 to receive placebo with doxorubicin and cyclophosphamide (AC) followed by weekly paclitaxel (arm A), bevacizumab only during AC and paclitaxel (arm B), or bevacizumab during AC and paclitaxel followed by bevacizumab monotherapy for 10 cycles (arm C). Random assignment was stratified and bevacizumab dose adjusted for choice of AC schedule. Radiation and hormonal therapy were administered concurrently with bevacizumab in arm C. The primary end point was invasive disease–free survival (IDFS).ResultsFour thousand nine hundred ninety-four patients were enrolled. Median age was 52 years; 64% of patients were estrogen receptor positive, 27% were lymph node negative, and 78% received dose-dense AC. Chemotherapy-associated adverse events including myelosuppression and neuropathy were similar across all arms. Grade ≥ 3 hypertension was more common in bevacizumab-treated patients, but thrombosis, proteinuria, and hemorrhage were not. The cumulative incidence of clinical congestive heart failure at 15 months was 1.0%, 1.9%, and 3.0% in arms A, B, and C, respectively. Bevacizumab exposure was less than anticipated, with approximately 24% of patients in arm B and approximately 55% of patients in arm C discontinuing bevacizumab before completing planned therapy. Five-year IDFS was 77% (95% CI, 71% to 81%) in arm A, 76% (95% CI, 72% to 80%) in arm B, and 80% (95% CI, 77% to 83%) in arm C.ConclusionIncorporation of bevacizumab into sequential anthracycline- and taxane-containing adjuvant therapy does not improve IDFS or overall survival in patients with high-risk human epidermal growth factor receptor 2–negative breast cancer. Longer duration bevacizumab therapy is unlikely to be feasible given the high rate of early discontinuation.

LBA1 Background: In hormone receptor (HR)-positive, HER2-negative, axillary node (AN)-negative breast cancer, the 21-gene expression assay (Oncotype DX Recurrence Score [RS]) is prognostic for distant recurrence, prognostic for low recurrence with endocrine therapy alone if low (0-10), and predictive of chemotherapy benefit if high (26 or higher). We performed a prospective, randomized trial of endocrine therapy (ET) versus chemoendocrine therapy (CET) in women with a mid-range RS of 11-25. Methods: Eligibility criteria included women 18-75 years of age with HR-positive, HER2-negative, axillary node (AN)-negative breast cancer and tumors 1.1-5.0 cm in size (or 0.6-1.0 cm and int/high grade) and agreed to have chemotherapy assigned or randomized based on the RS. Women with a mid-range RS (11-25) were randomized to receive ET or CET. The primary endpoint was invasive disease-free survival (iDFS), and the trial was designed to show non-inferiority for ET alone by not rejecting equality (hazard ratio [HR] margin up to 1.322 for omission of chemotherapy, 1-sided type I error rate 10%, type II error rate 5%). The target sample size was adjusted to compensate for non-adherence to randomized treatment, and the protocol-specified final analysis was triggered after 835 iDFS events. Results: Of the 10,253 eligible women enrolled between 4/7/06-10/6/10, 6711 (65.5%) had a RS of 11-25 and adequate information. There were 836 iDFS events at final analysis with a median followup of 90 months. ET was non-inferior to CET for iDFS (HR 1.08, 95% confidence intervals [CI] 0.94, 1.24, p=0.26) in the intention-to-treat (ITT) population. ET was also non-inferior for distant recurrence-free interval (DRFI; HR 1.03, p=0.80), recurrence-free interval (RFI; HR 1.12, p=0.28), and overall survival (OS; HR 0.97, p=0.80). Nine year rates were similar for iDFS (83.3% vs. 84.3%), DRFI (94.5% vs. 95.0%), RFI (92.2% vs. 92.9%), and OS (93.9% vs. 93.8%). Recurrence accounted for 338 (41.6%) the first iDFS event, of which 199 (23.8%) were distant recurrences. Treatment interaction tests were significant for age (iDFS p=0.03; RFI p= 0.02), but not menopause, tumor size, grade, or RS (continuous or RS 11-15, 16-20, 21-25). Conclusions: In women with HR-positive, HER2-negative, AN-negative breast cancer and a RS of 11-25, adjuvant ET was not inferior to CET in the ITT analysis. (Funded by NCI, BCRF, and Komen Foundation.) Clinical trial information: NCT00310180.

Abstract Background Celecoxib and low-dose aspirin might decrease risk of breast cancer recurrence. Methods In the Canadian Cancer Trials Group MA.27, postmenopausal hormone receptor–positive breast cancer patients were randomly assigned (2 × 2) to adjuvant exemestane or anastrozole, and celecoxib or placebo. Low-dose aspirin of 81 mg or less was a stratification factor. Due to concerns about cardiac toxicity, celecoxib use was stopped in December 2004, while stratification by aspirin use was removed through protocol amendment. We examined the effects of celecoxib and low-dose aspirin on event-free survival (EFS), defined as time from random assignment to time of locoregional or distant disease recurrence, new primary breast cancer, or death from any cause; distant disease–free survival (DDFS); and overall survival (OS). All statistical tests were two-sided. Results Random assignment to celecoxib (n = 811, 50.0%) or placebo (n = 811, 50.0%) was discontinued after 18 months (n = 1622). At a median of 4.1 years’ follow-up, among 1622 patients, 186 (11.5%) patients had an EFS event: 80 (4.9%) had distant relapse, and 125 (7.7%) died from any cause. Celecoxib did not statistically significantly impact EFS, DDFS, or OS in univariate analysis (respectively, P = .92, P = .55, and P = .56) or multivariable analysis (respectively, P = .74, P = .60, and P = .76). Low-dose aspirin use (aspirin users n = 476, 21.5%; non–aspirin users n = 1733, 78.5%) was associated in univariate analyses with worse EFS (hazard ratio [HR] = 1.48, 95% confidence interval [CI] = 1.12 to 1.96, P = 0.006) and worse OS (HR = 1.87, 95% CI = 1.35 to 2.61, P < .001). After adjusting for baseline characteristics and treatment arm, aspirin use showed no statistical association with EFS (P = .08) and DDFS (P = .82), but was associated with statistically worse OS (HR = 1.67, 95% CI = 1.13 to 2.49, P = .01). Conclusion Random assignment to short-term (≤18 months) celecoxib as well as use of low-dose aspirin showed no effect on DDFS and EFS in multivariable analysis. Low-dose aspirin increased “all-cause” mortality, presumably because of higher preexisting cardiovascular risks.