Aptose Biosciences, the U.S. partner of Hanmi Pharm in the development of HM43239, an acute myeloid leukemia (AML) treatment candidate containing tuspetinib, has announced the successful completion of a $3 million investment from Hanmi in the form of common shares in the company.

According to Aptose, the investment is the first tranche of a private equity investment for up to a maximum of $7 million or 19.99 percent ownership interest.

"The closing of the second tranche for up to $4 million or a maximum of 19.99 percent ownership interest will be triggered upon Aptose achieving certain manufacturing and data milestones related to tuspetinib before July 1, 2024," Aptose said. "The company currently anticipates achieving the milestones by year-end."

However, Aptose clarified that Hanmi may face restrictions in investing the remaining $4 million as outlined in the contract, which limits Hanmi's ownership to a maximum of 19.99 percent of the issued shares.

Using the investment from Hanmi, Aptose plans to provide additional financing for tuspetinib, which was licensed from Hanmi in November 2021.

The candidate is currently in the APTIVATE international phase 1 and 2 expansion trial in patients with relapsed or refractory acute myeloid leukemia (R/R AML).

In the trial, patients are either receiving tuspetinib as a monotherapy or in combination with venetoclax.

"We are grateful to our valued partner Hanmi Pharmaceutical for this investment and their confidence in our strategic direction," Aptose Chairman and CEO William G. Rice said. "Tuspetinib has demonstrated single-agent activity in critically ill AML patients across a diversity of genetically defined AML populations."

Importantly, tuspetinib in combination with the venetoclax BCL-2 inhibitor has been well tolerated and delivered responses in R/R AML patients who failed prior-venetoclax therapy, even among patients with wild-type FLT3 (FLT3-WT) and a TP53 mutation, Rice added.

Rice stressed that prior-venetoclax therapy failure patients represent a rapidly emerging unmet need in AML, and the continued favorable safety profile, convenience, and efficacy position the tuspetinib and venetoclax combo therapy as a potential therapy of choice in R/R AML.

Hanmi Pharm President Lim Ju-hyun also said, "Tuspetinib appears to have a clear development and commercial path forward with the potential to address large patient populations in AML."

Hanmi Pharm was unavailable for further comments regarding the investment.