Kronos Bio, Inc. announced an update on its pipeline. After a review of data from the phase 1b portion of its phase 1b/2 trial of lanraplenib in combination with gilteritinib in FLT3-mutated relapsed/refractory acute myeloid leukemia (AML), the Company has decided not to proceed to phase 2. Kronos Bio also announced the designation of a new development candidate, KB-9558, which targets the lysine acetyltransferase (KAT) domain of p300, a critical node of the IRF4 transcription regulatory network (TRN). IRF4 is a key driver in multiple myeloma.

KB-9558 is the second molecule to emerge from Kronos Bio?s proprietary product engine and is currently in IND-enabling studies, which are expected to be completed in the fourth quarter of 2024. Kronos Bio?s first internally discovered molecule, KB-0742, an inhibitor of CDK9, has demonstrated on-mechanism, single agent anti-tumor activity and a manageable safety profile in pre-treated patients with transcriptionally addicted solid tumors. KB-0742 recently cleared the 80 mg dose in the dose escalation portion of the ongoing phase 1/2 trial.

Patients currently in the two expansion cohorts will now be able to receive the 80 mg dose. The Company expects to provide data from the expansion phase of the trial in mid-2024. Kronos Bio will not proceed with the phase 2 portion of its phase 1b/2 trial of lanraplenib in combination with gilteritinib in patients with relapsed/refractory FLT3-mutated acute myeloid leukemia.

This decision was based on a review of the data from 24 patients across the four dose cohorts (20 ? 90 mg lanraplenib in combination with 120 mg gilteritinib). While there were blast reductions in some patients, no complete response (CR) or CR with partial hematologic recovery (CRh) was observed, with a number of patients discontinuing early in treatment.