Holmes, Eileen

502 Background: Pre-specified 5-year analyses of the phase III Adjuvant Lapatinib and/or Trastuzumab Treatment Optimisation (ALTTO) Trial defined in Amendments 11&12. Methods: From June 2007 to July 2011, 8381 patients (pts) were randomised from 946 sites in 44 countries to receive either L+T, T→L, L, or T. In 2011, due to futility the L arm was closed and is not included in this analysis. The primary end point is disease-free survival (DFS). Secondary objectives include treatment comparisons with respect to overall survival (OS), time to recurrence (TTR), time to distant recurrence (TDR), cardiac and overall safety and tolerability. Primary analysis results of the study were published in JCO 2015 34:1034-1042. This updated analysis occurs at a 6.9 yrs median follow up (MFU). Results: All patients have reached 5-years of follow-up. 705 DFS events for L+T vs T have been observed. HR for DFS was 0.86 (95% CI, 0.74-1.00; 6-yr DFS%=85% vs 82%) for L+T vs T and 0.93 (95% CI, 0.81-1.08; 6-yr DFS%=84% vs 82%) for T→L vs. T. The 6-year OS was 93%, 92%, and 91% for L+T, T→L, and T, respectively. HR for OS was 0.86 (95% CI, 0.70-1.06) for L+T vs. T and 0.88 (95% CI, 0.71-1.08) for T→L vs. T. DFS differences for L+T vs. T were slightly higher for the hormone-receptor(ER)-negative [HR 0.80 (95% CI, 0.64-1.00; 6-yr DFS%=84% vs. 80%)] and the sequential chemotherapy [HR 0.83 (95% CI, 0.69-1.00; 6-yr DFS%=83% vs.79%)] subgroups. There were no differences in sites of first DFS events according to treatment arm for CNS, loco-regional, or distant recurrences. There were more AEs related to study treatment (L+T 93% vs T 64%). The incidence of primary cardiac end points was low: 1% for L+T, 0.5% for T→L and 0.9% for T. Conclusions: The HRs for this updated analysis are similar to those from the Primary Analysis and the event rate remains lower than anticipated (705 vs 850 planned). Cardiac toxicity remains low. This analysis suggests that HER2+/ER- tumors may have a different biology than HER2+/ER+ and may benefit more from dual HER2 blockade. Long-term follow up continues. Clinical trial information: NCT00490139.

Background Lapatinib (L) plus trastuzumab (T) improves outcomes for metastatic human epidermal growth factor 2–positive breast cancer and increases the pathologic complete response in the neoadjuvant setting, but their role as adjuvant therapy remains uncertain. Methods In the Adjuvant Lapatinib and/or Trastuzumab Treatment Optimization trial, patients with centrally confirmed human epidermal growth factor 2–positive early breast cancer were randomly assigned to 1 year of adjuvant therapy with T, L, their sequence (T→L), or their combination (L+T). The primary end point was disease-free survival (DFS), with 850 events required for 80% power to detect a hazard ratio (HR) of 0.8 for L+T versus T. Results Between June 2007 and July 2011, 8,381 patients were enrolled. In 2011, due to futility to demonstrate noninferiority of L versus T, the L arm was closed, and patients free of disease were offered adjuvant T. A protocol modification required P ≤ .025 for the two remaining pairwise comparisons. At a protocol-specified analysis with a median follow-up of 4.5 years, a 16% reduction in the DFS hazard rate was observed with L+T compared with T (555 DFS events; HR, 0.84; 97.5% CI, 0.70 to 1.02; P = .048), and a 4% reduction was observed with T→L compared with T (HR, 0.96; 97.5% CI, 0.80 to 1.15; P = .61). L-treated patients experienced more diarrhea, cutaneous rash, and hepatic toxicity compared with T-treated patients. The incidence of cardiac toxicity was low in all treatment arms. Conclusion Adjuvant treatment that includes L did not significantly improve DFS compared with T alone and added toxicity. One year of adjuvant T remains standard of care.

Purpose We compared efficacy of trastuzumab versus no trastuzumab in patients with small (≤ 2 cm) human epidermal growth factor receptor 2 (HER2) –positive breast cancer treated in randomized trials. Methods A meta-analysis was conducted using data from five of the six adjuvant trastuzumab trials. Efficacy end points were disease-free survival (DFS) and overall survival (OS). Separate analyses were prospectively planned for hormone receptor (HR) –positive and HR-negative cohorts. Random effect models and Yusuf-Peto fixed effects models assessed the impact of heterogeneity on baseline hazards and treatment effects across studies. Peto-Pike cumulative incidence estimates were stratified by study and nodal status. Results Median follow-up time was 8 years. For 2,263 patients with HR-positive disease, 8-year cumulative incidence rates comparing trastuzumab versus no trastuzumab were 17.3% versus 24.3% (P < .001) for DFS and 7.8% versus 11.6% (P = .005) for OS, respectively; for 1,092 HR-positive patients with zero or one positive lymph nodes, results were 12.7% versus 19.4% (P = .005) for DFS and 5.3% versus 7.4% (P = .12) for OS, respectively. For 1,957 patients with HR-negative disease, 8-year cumulative incidence rates were 24.0% versus 33.4% (P < .001) for DFS and 12.4% versus 21.2% (P < .001) for OS, respectively; for 1,040 HR-negative patients with zero or one positive lymph nodes, results were 20.4% versus 26.3% (P = .05) for DFS and 8.2% versus 12.2% (P = .084) for OS, respectively. Conclusion Women with HER2-positive tumors ≤ 2 cm in the randomized trastuzumab trials derived substantial DFS and OS benefit from adjuvant trastuzumab. Trastuzumab-treated patients with HR-positive disease and ≤ one positive lymph node may be candidates for trials assessing less aggressive treatment approaches.

Abstract Background Trastuzumab (T) combined with chemotherapy improves survival of women with HER2-positive breast cancer. Dual therapy with T and other HER-2 targeted agents (lapatinib/pertuzumab) has demonstrated improved efficacy compared to T alone in advanced breast cancer, and is in clinical trials in early stage disease. We hypothesize that subgroups of patients with HER2-positive tumors and limited tumor burden (tumor size and no or few positive lymph nodes) have a favorable outcome and would not be candidates for dual therapy. This study will analyze the disease-free survival (DFS)and overall survival (OS) of patients with early stage breast cancer treated with chemotherapy and T in the seminal randomized studies (RCTs). Methods RCTs were identified by a Medline search from 2004-2013. Trial groups from five phase III RCTs agreed to provide data. TrialNumberEligibilityRegimenNSABP B312130T1-3; pN1, pN2a, or pN3a; M0ACx4 then Tx4 VSACx4 then THx4 then Hx40wkNCCTG N98313505T1-3; pN1-2; M0ACx4 then Tx12wk VS ACTx4 then Hx52wk VS ACx4 then Tx12wk then Hx40wkHERA5102T1-3; pN1-2; M0Any (neo)adjuvant regimen, then H q3wk x1yr VS H q3wk x 2yr VS observationFinHER232T1-4; N0-3; M0Vx3 or T*x3 then FECx3 VS Vx3 or T*x3 with Hx9wk then FECx3PACS043010(528 HER2+)T1-3; pN1-2; M0FE(100)Cx6 VSFE(100)Cx6 then Hx1yr VS T*E(75) x6 VS T*E(75) x6 then Hx1yrA, adriamycin; C, cyclophosphamide; T, paclitaxel; T*, docetaxel; H, trastuzumab; P, carboplatin; F, 5-fluorouracil; E, epirubicin; Treatment regimen also included 5 years of hormonal therapy for ER positive patients. The ER+/HER2+ and the ER-/HER2+ cohorts will be analyzed separately. Patients with tumors 3 cm or smaller (T1a, T1b, T1c and &gt;2 cm- 3cm) and 0, 1, 2 and 3 positive lymph nodes will be included. Initially a log rank test will be used to determine if the survival results are different by study. If there is no difference across studies, Kaplan-Meier survival curves with confidence intervals will be estimated. If there is a difference between studies, individual Kaplan-Meier curves will be estimated and the mean of the curves will be estimated along with confidence intervals using the adjusted standard deviation. Estimates at 3, 5 and 8 years will be presented as well as estimates of the event rates within each subpopulation defined by tumor size, number of positive lymph nodes, and ER status. Survival endpoints of DFS, and OS as defined in the original studies will be analyzed. Results and Conclusion Data from the five trials will be analyzed and an abstract provided prior to the meeting. Subgroups of patients with a very favorable outcome when treated with adjuvant chemotherapy and T will be identified. Our survival estimates might serve as benchmarks for future trials evaluating therapy reduction. Our results will complement those of the Dana Farber single arm multicenter trial in patients with “low risk” HER2-positive disease (APT trial; NCT00542451), being submitted to SABCS 2013. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr S6-03.

Abstract Background: Epidermal Growth Factor Receptor (EGFR, HER1) is known to heterodimerize with HER2 and may modulate the effectiveness of trastuzumab or lapatinib. Historically, it has been difficult to measure, but recently we reported a new, standardized, quantitative immunofluorescence assay and a novel EGFR antibody which showed that high levels of EGFR were associated with decreased benefit in the concurrent arm of the North Central Cancer Treatment Group (NCCTG/Alliance) N9831 trial (Rimm et al, SABCS 2012). Here we assess its value in the neo-adjuvant setting in the NeoALTTO trial. Methods: NeoALTTO randomized 455 breast cancer patients to neoadjuvant trastuzumab, lapatinib or both and showed benefit in both single anti-HER2 therapy arms, and the combination therapy showing about twice as much benefit as either single drug arm. We used the previously described AQUA method of quantitative immunofluorescence to measure EGFR levels using the D38B1 antibody on between 4 and 140 fields of view per slide on 353 specimens. The averaged EGFR score was standardized to the absolute concentration using cell lines and western blots and the 13 ng/ug total protein established in the N9831 trial was tested to determine predictive value for pathological complete response (pCR) defined as ypT0/is. Results: In NeoALTTO, 19% of the patients had EGFR levels above 13 ng/ug, compared to 16% in NCCTG N9831. The pCR rate was 35.3% in the patients with low EGFR, compared with 29.8% for high EGFR but this difference was not statistically significant. However, when adjusted for treatment and hormone receptor (HR) status, high EGFR is statistically significantly associated with lower response rate(p = 0.038). Continuous analysis measures were not significant. The effect on overall response at 6 weeks was also weakly significant when adjusting for treatment and HR status (p = 0.06). Surprisingly, for HR negative patients in the lapatinib only arm, the pCR rate in the low EGFR group was 47.2% compared with 16.0% in the high group. While this difference is statistically significant (p = 0.014), it should be interpreted cautiously because of the small numbers of patients and the multiple tests performed. Conclusions: High expression of EGFR by the AQUA platform appears to be associated with decreased pCR rate from HER2 targeted therapy in the neoadjuvant setting. This observation is consistent with NCCTG N9831. Although underpowered, high EGFR levels predicted decreased pCR rate from lapatinib, the opposite of that anticipated for this small molecule dual EGFR/HER2 inhibitor. Further studies are required to determine the clinical utility of this assay and the biological mechanisms underlying these observations. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P1-08-09.