Aptose Biosciences has scrapped a deal for a blood cancer drug candidate as part of its pending takeover by Hanmi Pharmaceutical.
Toronto-based Aptose paid $2 million to exercise its option on the drug candidate, the pan-FLT3/pan-BTK multikinase inhibitor CG-806, in 2018. In return, CrystalGenomics granted Aptose an exclusive license to the molecule everywhere except the Republic of Korea and China. Aptose paid $3 million for rights to the drug in China later in 2018.
As part of its second-quarter results, Aptose said it “is not permitted to pursue the further development” of the drug candidate because of its pending transaction with Hanmi. Korean biotech Hanmi agreed to buy Aptose last year—however, the completion of the deal was recently delayed by Korean regulatory processes.Â
Aptose expects the deal to close, albeit later than anticipated, and has returned rights, materials and data associated with CG-806 to CrystalGenomics. The transaction frees CrystalGenomics to “pursue business development opportunities with other identified parties,” Aptose said.
Aptose studied the molecule, also known as luxeptinib, in indications including chronic lymphocytic leukemia and acute myeloid leukemia. Studies revealed a need to improve drug absorption and increase exposure, leading Aptose to develop and test an updated CG-806 formulation in 2023 and 2024.
While studies linked the formulation to higher plasma levels and better tolerability than the original version, Aptose looked for alternative development paths and collaborations to advance the candidate. Later, the biotech paused funding for the program in light of its financial position and the prioritization of the acute myeloid leukemia treatment, tuspetinib.
Hanmi has bankrolled tuspetinib development in recent years, providing a loan in 2024 and making more cash available in 2025 and 2026. Aptose ended March with $4.1 million but received $3.1 million in two payments from Hanmi after the second quarter closed. After the payments, the biotech had received $7.1 million of the $11.1 million available to it from Hanmi through the end of May. Â
Facing tight finances, Aptose said it is “actively deploying cost reduction efforts” to extend its cash runway. Spending on luxeptinib fell in the second quarter, but overall operating expenses increased, in part because of a rise in investment in tuspetinib.