Efficacy and safety of PF-00299804 (PF299) in patients (pt) with advanced NSCLC after failure of at least one prior chemotherapy regimen and prior treatment with erlotinib (E): A two-arm, phase II trial

Abstract

8063 Background: Options are limited for pts with NSCLC following chemotherapy and E. PF299 is an oral irreversible small molecule inhibitor of the HER-1,-2, and -4 tyrosine kinases. Based on non-clinical and phase I NSCLC data, this ongoing phase II U.S. trial evaluates PF299 in pts with NSCLC (KRAS wild-type) who have progressive disease after at least 1 prior chemotherapy regimen and after E. Methods: Pts were enrolled by histology: adenocarcinoma (Arm A) and non-adenocarcinoma (Arm B), and received PF299 45 mg QD. Endpoints include objective response rate, duration of response, progression-free survival, survival, safety/tolerability, and pharmacokinetics. Pharmacodynamic endpoints include assessment of serum levels of HER2 and EGFR extracellular domains. Tissue and blood KRAS assays, and EGFR studies on available tissue, are also being performed. Forty-four and 22 response-evaluable pts were planned to be enrolled into Arms A and B respectively. Results: Thirty-four pts with progressive NSCLC (25 female, 14 smoker) have enrolled to date (Arm A: 30; Arm B: 4): median duration of prior E: 11.5 months; median time since E: 2.5 months. Among 20 response-evaluable pts, stable disease (SD) was observed in 9/18 pts in Arm A, and 1/2 pts in Arm B: median duration of SD: 11.5 weeks [range 6+, 32+ weeks]. Observation of disease control included pts who had recently (≤8 weeks) discontinued E; and also pts whose tumor had known EGFR T790M mutations. At time of data cutoff, confirmation per RECIST of 2 partial responses is pending. The most common treatment-related AEs were skin and gastrointestinal disorders, with grade 3 AEs in 19% and 13% of pts, respectively. Two pts experienced grade 4 pulmonary embolus/dyspnea deemed possibly treatment-related, both in the setting of progressive disease. Conclusions: PF299 shows encouraging activity in NSCLC pts after failure of prior chemotherapy and E. The AE profile was predictable and consistent with the prior phase I trial. At submission, enrollment in the adenocarcinoma arm is complete and enrollment in the non-adenocarcinoma arm continues; updated efficacy data and tumor characterization will be presented. [Table: see text]