A phase Ib safety and tolerability study of a pan class I PI3K inhibitor buparlisib
(BKM120) and gefitinib (gef) in EGFR TKI-resistant NSCLC.
Daniel Shao-Weng Tan, Kiat Hon Lim, Wai Meng Tai, Aziah Ahmad, Summer Pan, Quan Sing Ng,
Mei-Kim Ang, Apoorva Gogna, Yuen Li Ng, Bien Soo Tan, Haur Yueh Lee, Sakktee Sai Krisna,
Dawn PX Lau, Liz Zhong, Gopal Iyer, Balram Chowbay, Alvin ST Lim, Angela Takano, Wan-Teck Lim,
Eng-Huat Tan; National Cancer Centre, Singapore, Singapore; Department of Pathology, Singapore
General Hospital, Singapore, Singapore; Singhealth Investigational Medicine Unit, Singapore, Singapore;
Department of Radiology, Singapore General Hospital, Singapore, Singapore; Department of Dermatology,
Singapore General Hospital, Singapore, Singapore; Cytogenetics Laboratory, Singapore General Hospital,
Singapore, Singapore
Background: Overcoming EGFR TKI resistance (R) is a major clinical challenge; reported mechanisms
include EGFR T790M mutation (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 “313”
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 (n56), 100 mg/d (n56), 80 mg 5d
on 2d off (5/2, n53), with gef 250 mg/d. Gp A (n59, 1 CNS), B (n56, 1 CNS), F:M (9:6), median age 63
(47-73) and majority .3 lines of therapy. DLT was G3 diarrhea observed in 2/6 pt at BKM100. Common
adverse events (AE, all grades) include rash (80%), diarrhea (73%), fatigue (60%), anorexia (47%),
mucositis (40%). Notably, 40% of pt had late (beyond DLT period) G3 toxicities such as rash and diarrhea.
MTD is BKM 80/d and gef 250/d. To improve the overall safety profile, an intermittent schedule of BKM80
5/2 was also found to be feasible. In gp B, PET-CT done after 2 wk run-in of gef, 3/4 evaluable pt
demonstrated reduction in SUVmax of which 1 had PR. With addition of BKM, reduction in SUVmax
(.25%) was seen in 4/10 pt (gp A & B). Median PFS 2.8 m (95%CI 2.3 – 8.1), two pt in CNS gp had PFS
of 2.8 and 10.7 m. Molecular analyses revealed 6/12 (50%) harbored T790M mt, 2/5 (40%) MET amp, 0/12
PI3KCA mt. In gp A, 4/9 pt (2 T790M; 1MET amp) had clinical responses, including slight tumor shrinkage
and reduced pleural effusion, but required dose reductions due to AE. PK profiles are being analyzed.
Conclusions: MTD is gef 250-BKM 80/d. Antitumor activity has been observed with addition of BKM in
EGFR TKI-R pt. In view of late toxicities and long t½ of BKM, exploring alternative schedules is warranted.
A dose expansion cohort at MTD is currently ongoing. Clinical trial information: NCT01570296. |