Kronos Bio, Inc. announced a plan to optimize its resource allocation, restructure, and extend runway to focus resources on key programs in the Company?s pipeline, including the ongoing phase 1/2 study of KB-0742 following the review of additional positive preliminary safety and efficacy data. This plan positions the Company to maximize the potential of KB-0742, an inhibitor of CDK9, by exploring an extended dosing schedule while also continuing to progress KB-9558, a p300 KAT inhibitor, through ongoing IND-enabling studies and into the clinic, and its discovery efforts and collaborations. To date, anti-tumor activity has been observed without grade 3/4 neutropenia in patients treated with KB-0742 at doses ranging from 10mg to 80mg using the current three-days-on, four-days-off dosing schedule.

The Company has reported target engagement, tumor regressions, and an acceptable safety profile at 60mg dosed three-days-on, four-days-off. KB-0742 cleared 80mg three-days-on, four-days-off and the Company expects to publish this data in addition to the 60mg expansion mid-year. As disclosed earlier this week, the Company plans to escalate to 80mg four-days-on, three-days-off, a dosing schedule that offers patients significantly increased time at or above a therapeutic threshold compared to the already established active dose of 60mg dosed three-days-on, four-days-off.

The amended protocol leverages a 3+3 design, placing the Company on a path to efficiently clear the dose levels, and the Company expects to share topline data from the expansion cohort at this dose schedule in the first half of 2025. In December, KB-0742 cleared the 80mg dose in the dose escalation portion of the phase 1/2 trial using a three-days-on, four-days-off dosing schedule. Before escalating to the planned dosing schedule of 80mg four-days-on, three-days-off, the Company is currently evaluating 60mg of KB-0742 four-days-on, three-days-off in three evaluable patients as contemplated by a 3+3 design.

If the safety profile of KB-0742 remains acceptable, the Company will then evaluate safety in three additional patients at 80mg four-days-on, three-days-off prior to enrolling patients in an expansion cohort. The Company currently contemplates the expansion cohort will include patients with either small cell or non-small cell lung cancer, ovarian cancer, or triple negative breast cancer, and expects to provide an update later in the year on which tumor type(s) will be included in the expansion cohort. The Company intends to present updated data at a medical meeting in mid-2024 based on data that have been collected from patients who have received doses of KB-0742 of 60mg or 80mg using the prior three-days-on, four-days-off dosing schedule.

In the third quarter of 2024, the Company expects to provide an update from the new four days per week dosing schedule and announce its plans for the dose expansion portion of the phase 1/2 trial. In the first half of 2025, Kronos Bio plans to present topline safety and efficacy data at a medical meeting from patients on the new four-days-on, three-days-off dosing schedule. On April 8, 2024, Kronos Bio will present preclinical data on KB-9558 in multiple myeloma at the American Association for Cancer Research (AACR) annual meeting in San Diego, California.

Pending the completion of IND-enabling studies in 2024, the Company expects to commence a first-in-human study in multiple myeloma in 2025.