ABL Bio has decided to halt the development of its bispecific antibody immuno-oncology candidate, ‘ABL501,’ three years after receiving phase 1 clinical trial approval from the Ministry of Food and Drug Safety in August 2021.

ABL Bio revealed this decision through its website following the disclosure of the phase 1 trial results on August 30. ABL501 is a bispecific antibody that targets PD-L1 and LAG-3, using ABL Bio’s immunomodulatory bispecific antibody platform, ‘Grabody-I.’ ABL Bio had been developing ABL501 to overcome the low response rate and resistance, which are limitations of existing PD-(L)1 immunotherapies.

ABL501 had been selected as a project under the Ministry of Health and Welfare’s Advanced Medical Technology Development Program, receiving support for preclinical research, and the phase 1 clinical trial had also been selected as a clinical development project under the National New Drug Development Program, receiving research and development funding. ABL Bio explained that this decision was based on the phase 1 results disclosed recently and the current research and development strategy.

The phase 1 trial for ABL501 was conducted at four institutions, including Samsung Medical Center, targeting patients with advanced, locally advanced (unresectable), or metastatic solid tumors. The trial was approved by the Korean Ministry of Food and Drug Safety, and a total of 24 patients participated. 

The trial was designed as an open-label, single-arm, multi-center, multiple-dose study, with the primary goals of determining the maximum tolerated dose (MTD) or maximum administered dose (MAD) and evaluating the drug’s safety and tolerability. The trial results showed that dose-limiting toxicity (DLT) occurred in one participant at the highest dose level, ‘Cohort 6,’ out of 21 patients, and the MAD was confirmed at Cohort 6. 

The MTD was not reached. In the safety evaluation, drug-related adverse events occurred in 75% (18 out of 24 patients), with one case (4.17%) of a grade 3 or higher serious adverse event.