Phase 1 Study of PKC412, an Oral FLT3 Kinase Inhibitor, in Sequential and Concomitant Combinations with Daunorubicin and Cytarabine (DA) Induction and High-Dose Cytarabine (HDAra-C) Consolidation in Newly Diagnosed Patients with AML.

The Fms-like tyrosine kinase 3 (FLT3), a receptor expressed in 80% of AML patients, is constitutively activated in 25–35% of adult AML patients due to mutations, in the form of either ITDs or activating loop point mutations, most commonly at D835Y. PKC412 is an oral multi-targeted tyrosine kinase inhibitor known to potently inhibit both activated wild type (WT) and mutated (mut) FLT3 kinase. PKC412 (100 mg po bid) was tested in a phase IB study in newly diagnosed AML patients between 18 and 60 years of age (both WT and mut FLT3) in combinations with DA for induction therapy (up to 2 cycles) and HDAra-C for consolidation (up to 3 cycles).

Study design: PKC412 was given daily beginning on Day 8 (Arm 1) or Day 1 (Arm 2) of induction chemoRX in cycle 1. Primary endpoints were PK, tolerability, and safety as defined by fewer than 2 drug-related deaths in the initial cohort of 6 pts per arm (stage 1) and fewer than 4 drug-related deaths among the total 20 pts per arm (stage 2) during induction.

Results: 15 pts were enrolled (median age 50; 1 FLT3 ITD+, 14 WT; ): 7 in Arm 1 and 8 in Arm 2. Cytogenetic prognostic categories of the 15 patients were: 0 (good), 9 (intermediate) and 6 (bad). Of the 15 pts, 14 were evaluable for toxicity; 1 pt did not receive PKC412; no drug-related deaths were observed during induction therapy. The most common G3 drug-related toxicities included: nausea (46%), vomiting (32%), transaminitis (18%), and hyperbilirubinemia (18%), all were transient and/or reversible. 13/15 patients were evaluable for response: 2 pts were not evaluated: one pt never received PKC412 and one pt did not complete the full-course of induction chemoRx; 3/7 (43%) achieved a CR in Arm 1 and 3/6 (50%) achieved a CR in Arm 2. 3 pts have completed the study (Days 143, 141, 132) and one pt is ongoing (Day 127). Because of the high rate of G3 nausea and vomiting, the study was amended, (5 patients are ongoing) such that PKC412 is given with each cycle of chemoRx on either Days 1–7 and 15–21 (Arm 1), or on Days 8–21 (Arm 2).

Conclusions: PKC412 can be given safely in newly diagnosed AML patients in combinations with DA and HDAra-C chemoRx. An update of this study, along with PK data of PKC412, daunorubicin, and Ara-C levels will be presented.