Purpose: Neratinib, an irreversible pan-HER tyrosine kinase inhibitor, has demonstrated systemic efficacy and intracranial activity in various stages of HER2+ breast cancer. NALA was a phase III randomized trial that assessed the efficacy and safety of neratinib + capecitabine (N+C) against lapatinib + capecitabine (L+C) in HER2+ metastatic breast cancer (mBC) patients who had received ≥2 HER2-directed regimens. Descriptive analysis results of the Asian subgroup in the NALA study are reported herein.
Methods: 621 centrally-assessed HER2+ mBC patients were enrolled, 202 of whom were Asian. Those with stable, asymptomatic brain metastases (BM) were eligible for study entry. Patients were randomized 1:1 to N (240mg qd) + C (750mg/m2 bid, day 1-14) with loperamide prophylaxis, or to L (1250mg qd) + C (1000mg/m2 bid, day 1-14) in 21-day cycles. Co-primary endpoints were centrally-assessed progression free survival (PFS) and overall survival (OS). Secondary endpoints included time to intervention for central nervous system (CNS) disease, objective response rate, duration of response (DoR), clinical benefit rate, and safety.
Results: 104 and 98 Asian patients were randomly assigned to receive N+C or L+C, respectively. Median PFS of N+C and L+C was 7.0 and 5.4 months (P=0.0014), respectively. Overall cumulative incidence of intervention for CNS disease was lower with N+C (27.9 versus 33.8%; P=0.039). Both median OS (23.8 versus 18.7 months; P=0.185) and DoR (11.1 versus 4.2 months; P<0.0001) were extended with N+C, compared to L+C. Diarrhea was the most frequent treatment-emergent adverse event (TEAE) in both arms (78.8 versus 51.0%). The incidence of grade 3/4 TEAEs and TEAEs leading to treatment discontinuation was comparable between the two arms.
Conclusion: Consistent with the efficacy profile observed in the overall study population, Asian patients with HER2+ mBC, who had received ≥2 HER2-directed regimens, may also benefit from N+C. No new safety signals were noted.
Clinical Trial Registration: NCT01808573