Bischofberger's Kronos files for IPO to run pivotal cancer trial

Norbert Bischofberger’s Kronos Bio has filed to raise up to $100 million in a Nasdaq IPO. The IPO haul will set Kronos up to start a registrational phase 2/3 trial of a first-line acute myeloid leukemia (AML) drug licensed from Bischofberger's former employer Gilead.

Kronos set out in 2017 to use its small molecule microarray platform to identify targets on proteins that are impossible to drug using conventional methods. Last year, Kronos raised $105 million to take its lead assets through preclinical. Then, just months ago, Kronos accelerated its progress by picking up a portfolio of SYK inhibitors from Gilead led by clinical-phase cancer prospect entospletinib.

Gilead published data on the use of entospletinib in combination with induction chemotherapy in AML patients in 2018 but, with the cocktail delivering a complete response rate in line with historical results from standard of care, the big biotech never forged ahead into another study.

Kronos sees an opportunity to deliver more impressive results by zeroing in on AML patients with NPM1 mutations. A retrospective analysis of 53 AML patients studied by Gilead found the complete response rate in patients with NPM1 mutation was 87%. The response rate in patients without any mutation was 54%.

The figures were generated in a retrospective analysis of small numbers of patients, raising the risk that they give a false impression of the efficacy of entospletinib in the genetic subpopulation. But the data are in line with Kronos’ preclinical hypothesis, emboldening it to move into phase 2/3. 

Kronos plans to talk to regulators about the study in the first half of 2021 and begin the trial later in the year. If Kronos hits that timeline, it expects to have data from the registrational study in 2023.

The biotech needs money to bankroll the plan, including to make a $29 million payment to Gilead upon the initiation of the phase 2/3, and has turned to public investors for support. Kronos wants to raise enough money to fund its phase 2/3 and a planned phase 1/2 trial of CDK9 inhibitor KB-074 in advanced solid tumor patients. The phase 1/2 is due to start next year. 

Kronos’ pipeline reflects its focus on transcriptional regulatory networks (TRNs), clusters of proteins that manage gene expression to control healthy cell development and function. TRNs can become dysregulated for reasons including aberrant transcription factor expression, leading to cancer cells. Kronos is set up to identify critical nodes in TRNs and, in doing so, find new ways to treat disease.

The availability of Gilead’s SYK inhibitors for licensing is enabling Kronos to accelerate the validation of its thinking. Kronos paid $3 million upfront in cash and issued a $3 million convertible promissory note to Gilead to secure the assets. Bigger payouts are to come, starting with the $29 million upon the initiation of the phase 2/3 and continuing through to up to $115 million in sales milestones.