A phase Ib study of oral Chk1 inhibitor LY2880070 as monotherapy in patients with advanced or metastatic cancer.

Abstract

3579 Background: LY2880070 (LY) is an orally-administered, selective adenosine triphosphate-competitive inhibitor of checkpoint kinase 1 (Chk1). LY blocks the checkpoint response, and Chk1 inhibition results in mitotic catastrophe to produce apoptosis. Methods: This 2-part, open-label multi-center study explores the safety, pharmacokinetics (PK) and anti-tumor activity of LY in patients with advanced or metastatic cancers. The primary objective of this study was to determine the maximum tolerated dose (MTD) for multiple escalating oral doses of LY. Secondary objectives were to: 1) Characterize the dose-limiting toxicities (DLTs) and overall safety profile for LY; 2) Evaluate the PK of LY; and 3) Evaluate the anti-tumor activity of LY. Patients received LY orally in 21-day cycles in two treatment arms: 1) A multiple ascending dose (MAD) arm in patients with normal/intermediate CYP2D6 metabolism; or 2) An arm with LY administered as monotherapy to CYP2D6 poor metabolizers. Results: The MTD in normal/intermediate CYP2D6 metabolizers was 200 mg BID daily. A dose of 400 mg QD was not tolerated even with the use of anti-emetics. However, BID administration (same total daily dose) made LY tolerable. Dose-limiting toxicities were predominantly vomiting, nausea, and fatigue, and appeared to be correlated with Cmax. The mean half-life was 5.35 (+/- 2.3) hours. BID dosing provided maintenance of the AUC (3271.4 h∙ng/mL 200 mg BID vs 3377.9 h∙ng/mL 400 mg QD) while lowering Cmax (350.0 ng/mL 200 mg BID vs 691.9 ng/mL 400 mg QD) and increasing Cmin, compared to QD dosing of the same total daily dose. Importantly, BID administration of 200 mg LY resulted in a median Cmin at steady-state that remains above the IC80 for 12 h/day and above the IC50 for 24 h/day. Five patients had a best response of SD for a duration of ≥ 6 cycles. Conclusions: LY was tolerated in a daily BID schedule. The toxicity profile can be modulated by changing the dosing frequency from QD to BID while administering the same daily dose. LY may be a potential combination therapy with DNA damaging agents. Study #: NCT02632448 . This study is sponsored by Esperas Pharma Inc., 1255 boul. Robert-Bourassa #1610, Montreal, Qc, H3B 3X3. Clinical trial information: NCT02632448 .