MA04.02 Neratinib ± Temsirolimus in HER2-Mutant Lung Cancers: An International, Randomized Phase II Study

Combined inhibition of HER2 and mTOR is synergistic in models of HER2 (or ERBB2)-mutant lung cancers. PUMA-NER-4201 is an adaptive, multinational, randomized phase II study comparing the pan-HER inhibitor neratinib (Puma Biotechnology) ± the mTOR inhibitor temsirolimus in patients with advanced HER2-mutant lung cancers. In stage 1 of the study, neratinib + temsirolimus met predefined criteria for expansion into stage 2 [Besse et al. ESMO 2014]. Patients with stage IIIB/IV locally determined HER2-mutant cancers were randomized to receive oral neratinib 240 mg once daily ± intravenous temsirolimus 8 mg once weekly (escalated to 15 mg/week after a 3-week cycle if tolerated) with loperamide prophylaxis. Primary endpoint: overall response rate (RECIST v1.1). Secondary endpoints: duration of response, progression-free survival, overall survival, toxicity assessments (NCI-CTCAE, v4.0). ClinicalTrials.gov: NCT01827267. Of 62 randomized patients, 60 received ≥1 dose of neratinib: neratinib alone (n=17); neratinib + temsirolimus (n=43). Baseline characteristics: male/female 32%/68%; median age 66 years; never smokers 60%; adenocarcinoma 98%. HER2 (or ERBB2) mutation type: exon 20 insertions 93.5%; missense substitutions 3.2%; unspecified 3.2%. The most common HER2 allelic variant was A775_G776insYVMA. Exploratory biomarker analysis from available tumor and plasma samples will be presented at the meeting. Efficacy and safety results are shown in the table. With loperamide prophylaxis, the incidence of grade 3 diarrhea was 12% with neratinib and 14% with neratinib + temsirolimus, which lasted for a median duration of 1.5 (interquartile range, 1.0‒2.0) days and 4.0 (interquartile range, 2.0‒16.0) days, respectively. Neratinib (240 mg/day) + temsirolimus (8 or 15 mg/week) produced responses lasting 2 to 18+ months in 19% of patients with HER2-mutant lung cancers. Correlative data will be presented at the meeting. Diarrhea was manageable with loperamide prophylaxis.