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- At effective doses of 3mg/kg and 5mg/kg, CR and PR cases were reported
- Safety findings were manageable with steroid treatment, etc.
ABL Bio (CEO Sang Hoon Lee), a company specializing in bispecific antibody development, today announced that it successfully completed its poster presentation on the interim Phase 1 clinical data of ABL503 (TJ-L14B, ragistomig) at the 2024 Annual Meeting of the American Society of Clinical Oncology (ASCO 2024). The ABL503 poster was presented at ASCO’s Developmental Therapeutics Immunotherapy session on June 1st.
ABL503 is a bispecific antibody being jointly developed by ABL Bio and its global partner I-Mab Biopharma, using ABL Bio’s 4-1BB-based bispecific antibody platform ‘Grabody-T’. It simultaneously targets PD-L1, an immune checkpoint protein and 4-1BB, which is involved in immune T cell activation. Currently, a Phase 1 clinical trial for patients with solid tumors is underway in the United States and Korea. The dose escalation portion of the study is underway in the United States. Two segments of the study are ongoing in the United States and Korea: the dose expansion portion of the study, focused on the preliminary antitumor activity of a specific dose for which safety has been confirmed, and the tumor expansion portion, which is being carried out for selected specific cancer types.
As of the data cut-off date, a total of 53 patients were enrolled in the study, including 34 participants from the dose escalation portion and 19 participants from the dose expansion part. Among the patients enrolled, 56.6% did not respond to existing PD-(L)1 inhibitor treatment or had a recurrence of cancer after PD-(L)1 treatment. The majority of patients were heavily pretreated before participating in the clinical trial.
Among the 44 efficacy-evaluable patients, one complete response (CR) and six partial responses (PRs) were observed at the cut-off date of April 19, 2024. Five of these patients did not respond to prior PD-(L)1 inhibitor treatment or experienced cancer recurrence after PD-(L)1 treatment. Notably, the one patient who experienced a CR had been diagnosed with ovarian cancer and had received more than seven prior treatments, including recurrence after prior PD-(L)1 inhibitor treatment.
The seven patients who experienced a response (a CR or a PR) received ABL503 at the effective dose levels of 3mg/kg and 5mg/kg. The Overall Response Rate (ORR) of ABL503 observed at the effective dose was 26.9% (7/26), and the Clinical Benefit Rate (CBR) was 69.2% (18/26).
Safety was found to be manageable. At least one Treatment-related Adverse Event (TRAE) was reported in 40 patients. The most common TRAE was increased alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels, and those patients with grade 3 or higher ALT and AST levels were managed with steroid treatment. In addition, all five patients who experienced dose-limiting toxicity have recovered or are recovering, and the maximum tolerated dose identified was 7mg/kg, dosed every two weeks.
Sang Hoon Lee, CEO of ABL Bio said, “PD-(L)1 inhibitors, including pembrolizumab, a global blockbuster with 2023 sales of $25 billion, are widely used in the treatment of various cancer types, but many patients do not respond to this treatment, which creates an unmet medical need. ABL503 has shown promising results to date, with one CR and multiple PRs, in patients who have not responded to prior PD-(L)1 inhibitor treatment or who have relapsed.” and stated, “the treatment-related increase in AST and ALT caused by ABL503 occurs not only with ABL503 but also with treatments targeting PD-(L)1, and the Phase 1 data suggest that recovery is possible. ABL Bio plans to consider future clinical strategies by comprehensively understanding these interim data and additional results confirmed in the ongoing Phase 1 clinical trial.”
Meanwhile, ABL Bio is developing various clinical and non-clinical assets based on the bispecific antibody platform ‘Grabody.’ More than 15 clinical projects for more than seven assets, including ABL001, ABL111, ABL503, ABL105, ABL202, ABL301, and ABL103, are underway for different indications in various countries, including the United States, China, Australia, and Korea. In the case of ABL001, the U.S. Food and Drug Administration (FDA) recently granted Fast Track designation to support the rapid development of new drugs. Assets such as ABL104 are also being prepared to enter clinical trials. In addition, ABL Bio is continuously researching and developing several other non-clinical pipeline drug candidates, including bispecific ADCs.