Abstract No. 2524
Title: First-in-human evaluation of CO-1686, an irreversible, selective, and potent tyrosine kinase inhibitor of EGFR T790M.
Background: Efficacy of existing EGFR tyrosine kinase inhibitors (TKIs) in NSCLC is limited by emergence of the T790M mutation in approximately 50% of patients, and significant skin rash and diarrhea, caused by wild-type (WT)-EGFR inhibition, compromises tolerability. CO-1686 is an orally active TKI that targets common activating EGFR mutations and T790M, while sparing WT-EGFR. Animal models suggest maximal efficacy when trough plasma concentrations exceed 200ng/ml.
Methods: This is a first in human phase 1 (3+3) dose-finding study of oral CO-1686, administered continuously in 21-day cycles. To be eligible, patients must have EGFR-mutant NSCLC and prior therapy with an EGFR TKI. Endpoints include safety, pharmacokinetics (PK), and efficacy. All patients undergo a biopsy for genotyping before starting study drug.
Results: As of 18 Jan 2013, 35 patients (18/28 (64%) T790M+; 7 pending) have been treated with CO-1686. Dosing started at 150mg QD and escalated in steps to 900mg QD, 600mg BID and 400mg TID, with a maximum tolerated dose not yet reached. A recommended phase 2 dose is expected to be reached soon. Related AEs of grade 3 or higher were hypoglycaemia (n=1) and hyperglycaemia (n=1). AEs typical of WT-EGFR inhibition (rash, diarrhea) have not been observed. Dose-proportional PK was observed; plasma half-life was 4-5 hrs and at 900mg QD Cmax=3000ng/ml but trough concentrations were less than 200ng/ml. At greater than or equal to 300mg BID and TID dosing, trough concentrations can exceed 200ng/ml. At 900mg QD, 2 of 3 patients showed clinical benefit after 2 cycles of CO-1686 including one with clinically-relevant tumor shrinkage (18%) and a second with stabilization of a pleural effusion that had previously required repeat thoracenteses at ~10 day intervals. At 300mg BID, one patient (Del(19)/T790M+) with PK trough concentration greater than 200ng/ml exhibited significant tumor shrinkage (29%) after 2 cycles. Further efficacy data from BID/TID cohorts and centrally-confirmed genotypes will be presented at the meeting.
Conclusions: CO-1686 offers potential for improved activity and better tolerability over current EGFR TKIs, particularly in the treatment of T790M+ disease, an area of high unmet clinical need.
Abstract No. 2503
Title: Phase I study of safety and pharmacokinetics (PK) of GDC-0917, an antagonist of inhibitor of apoptosis (IAP) proteins in patients (Pts) with refractory solid tumors or lymphoma.
Background: GDC-0917 is a small molecule that triggers tumor cell apoptosis by selectively antagonizing IAP proteins. Preclinical studies demonstrated antitumor efficacy of GDC-0917 alone or in combination with chemotherapeutic agents.
Methods: Oral GDC-0917 was given on Day (d) 1 followed by 2d off and a 2-week (w) on/ 1w off treatment (tx) schedule (21d cycle) starting d4. A modified continual reassessment method was used for dose escalation. Dose-limiting toxicity (DLT, assessed d1-24), PK, adverse events (AEs), pharmacodynamics (PD), and clinical activity were evaluated.
Results: 42 pts of age 36-86 (median 60.5) were enrolled in 11 cohorts (5-600 mg) and received 1-15 cycles (median 2) of GDC-0917. One DLT, Grade (G) 3 fatigue, was observed at 450 mg. The maximum tolerated dose was not determined although plasma concentrations of preclinically defined IC90 were reached. The most frequent AEs were diarrhea, fatigue and nausea (26.2% each), vomiting (23.8%), and constipation (19%). The most frequent AEs reported as tx-related were mostly G1-2 and included fatigue and nausea (21.4% each), vomiting (14.3%), rash (11.9%) and pruritus (9.5%). AEs reported as tx-related that were greater than or equal to G3 in greater than 1 pt were elevated AST and ALT (2 pts, at 450 and 600 mg). AEs reported as tx-related that resulted in tx discontinuation were G3 fatigue, G2 QTc prolongation, G2 drug hypersensitivity, G2 pneumonitis (1 pt each), and G3 pruritus/G2 rash (same pt). GDC-0917 peak concentrations were observed 2-3h post dosing. Exposure was dose-proportional with a mean plasma elimination t1/2of 4-8h and no apparent accumulation at steady state. Rapid down-modulation of cIAP1 was observed in PBMCs at all dose levels. Evaluation of tumor biopsies demonstrated decreases in cIAP1 (2 pts total, at 40 and 200 mg) and increases in activated caspase-3 and cPARP (1 pt at 200 mg). Two pts (4.8%) had a complete response (both unconfirmed, ovarian Ca and MALT lymphoma [PET]); 4 pts (9.5%) had stable disease for greater than or equal to 3 months.
Conclusions: GDC-0917 had a favorable safety, PK and PD profile in pts with advanced malignancies. These encouraging results support further clinical evaluation of this agent.