Xu, Binghe

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.

LBA4 Background: Lapatinib (L) is a HER1-HER2 tyrosine kinase inhibitor. The Adjuvant Lapatinib and/or Trastuzumab Treatment Optimisation (ALTTO) Trial is a randomised, phase III trial comparing 3 oral L-containing regimens with T, each given for 1 year. 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. Anti-HER2 therapy was initiated after completing all chemotherapy (N=4613), concurrently with a taxane following anthracycline (N=3337), or concurrently with a non-anthracycline, platinum-containing regimen (N=431). The L arm was closed in Aug 2011 for futility and is not presented. The primary endpoint is invasive disease-free survival (DFS). L+T vs. T is tested for superiority and T→L vs. T is tested for non-inferiority at 1.11 margin. P≤0.025 is required for statistical significance. 850 DFS events in the L+T vs. T comparison would provide 80% power to detect a true hazard ratio (HR) of 0.80 with experiment-wide alpha=0.05. The current analysis was planned to occur either after observing these 850 events or at 4.5 yrs median follow up (MFU). Results: Pt and disease characteristics were well balanced. 40% were node-negative and 57% were hormone receptor positive. Only 555 DFS events for the L+T vs. T comparison were observed at 4.5 years MFU. HR for DFS was 0.84 (97.5% CI, 0.70-1.02; P=0.048; 4-yr DFS%=88% vs. 86%) for L+T vs. T and 0.93 (97.5% CI, 0.76-1.13; non-inferiority P=0.044; 4-yr DFS%=87% vs. 86%) for T→L vs. T. Diarrhoea (75% vs. 20%), rash (55% vs. 20%) and hepatobiliary (23% vs. 16%) adverse events were more frequent in L+T vs. T. Primary cardiac endpoints were infrequent (<1%) in all arms. Conclusions: L+T has lower risk of a DFS event compared with T, and T→L appeared non-inferior to T, but neither finding was statistically significant. The first DFS results of dual HER2 blockade in the adjuvant ALTTO at 4.5 years MFU are unexpected considering the effect shown by doubling the pCR rate with L+T vs. T in the NeoALLTO trial. Follow up continues. Clinical trial information: NCT00490139.

Abstract Background: We have previously shown in a phase III neoadjuvant trial that early development of lapatinib-induced rash (i.e. within 6 weeks after lapatinib initiation) is independently associated with a higher chance of obtaining a pathological complete response (Azim et al; JCO 2013). In the current study, we aimed to investigate whether early lapatinib-induced rash is associated with improved survival in the context of a large phase III adjuvant trial. Methods: This analysis is based on the ALTTO trial (BIG 2-06, Alliance N063D), in which patients with HER2-positive early breast cancer were randomized to adjuvant trastuzumab, lapatinib, their sequence or their combination for a total duration of 1 year. In this sub-study, we evaluated whether the development of rash (any grade) within 6 weeks of lapatinib initiation was associated with disease-free (DFS) and overall survival (OS). All analyses were tested in a multivariate model adjusted for treatment arm, treatment completion and trial stratification factors. Results: A total of 6,098 lapatinib-treated patients were included in the current analysis; of whom 2,006 patients (32.9%) developed early lapatinib-induced rash, 1,025 (16.8%) developed rash after 6 weeks and 3,067 (50.3%) did not develop rash. No differences in patient characteristics were observed between the three groups apart from a higher frequency of younger patients (≤ 50) in the early rash group (54% vs. 47% and 44%, p&lt;0.0001). At a median follow-up of 4.5 years, 876 (14.37%) and 377 (6.18%) patients in the lapatinib containing arms experienced a DFS and OS event, respectively. In a multivariate analysis confined to patients randomized to the lapatinib containing arms, the development of early rash was associated with improved DFS (HR: 0.80; 95%CI: 0.69-0.93, p=0.004) and OS (HR: 0.61; 95%CI: 0.48 - 0.78, p&lt;0.001) compared to patients who did not develop early rash, with no interaction according to patient's age (p=0.9). No significant association was observed between the development of rash after 6 weeks of lapatinib initiation and survival. Compared to patients randomized to the trastuzumab alone arm (n=2,076), patients who developed early rash in the sequence (n=580) or combination (n=704) arms of trastuzumab/lapatinib had superior DFS (Sequence: HR 0.75 [95% CI: 0.58 – 0.98], p=0.034; Combination: HR 0.69 [95% CI: 0.54 – 0.89], p=0.005) and OS (Sequence: HR 0.57 [95%CI: 0.36 – 0.88], p=0.012; Combination: HR 0.59 [95% CI: 0.39 – 0.89], p=0.011). On the other hand, patients randomized to the lapatinib only arm who developed early rash (n=722) still had inferior DFS (HR 1.28 [95% CI: 1.04 – 1.59], p=0.02) with no difference in OS (HR: 0.95; 95%CI: 0.67 – 1.35, p=0.79) compared to patients randomized to the trastuzumab alone arm. Conclusions: The results support our previous findings in the neoadjuvant setting that early development of skin rash within the first 6 weeks can identify patients who derive superior benefit of lapatinib treatment. Citation Format: Azim Jr HA, Sonnenblick A, Agbor-Tarh D, Bradbury I, Daly F, Huang Y, Dueck AC, Pritchard K, Wolff AC, Jackisch C, Lang I, Untch M, Smith I, Boyle F, Xu B, Gomez H, Perez E, Piccart M, de Azambuja E. The impact of early lapatinib-induced rash on disease-free and overall survival in patients treated within the ALTTO phase III randomized trial. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr PD5-07.

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.