A phase Ib safety and tolerability study of a pan class I PI3K inhibitor buparlisib (BKM120) and gefitinib (gef) in EGFR TKI-resistant NSCLC.

8107 Background: Overcoming EGFR TKI resistance (R) is a major clinical challenge; reported mechanisms include EGFR T790Mmutation (mt), MET amplification (amp) and PIK3CA mt. As the PI3K pathway is a central convergent signaling node, we hypothesized that addition of buparlisib(BKM) could overcome EGFR TKI-R. Methods: Patients (pt) resistant to EGFR TKI (Jackman JCO 2010) were enrolled to determine safety, tolerability, pharmacokinetics (PK) and pharmacodynamics of BKM-gef. Using a “3+3” design, escalating doses of BKM were added to pt progressing on gef (Gp A). Pt not on gef preceding enrolment received a 2 wk run in (Gp B). Given the favorable CNS penetration of BKM, a CNS gp with brain metastases only was included. Pt had pretreatment biopsies and sequential PET-CT scans (baseline & d28). Results: 15 pt have been treated at 3 dose levels: BKM 80 mg/d (n=6), 100 mg/d (n=6), 80 mg 5d on 2d off (5/2, n=3), with gef 250 mg/d. Gp A (n=9, 1 CNS), B (n=6, 1 CNS), F:M (9:6), median age 63 (47-73) and majorit...