ROCKVILLE, Md., May 23, 2024 - I-Mab (NASDAQ: IMAB), a leading global biotechnology company focused on innovative immunotherapies for cancer treatment, has announced favorable preliminary results from a Phase 1 trial of ragistomig (also known as ABL503). This data will be showcased during the 2024 Annual Meeting of the American Society of Clinical Oncology (ASCO 2024) in Chicago, IL, from May 31 to June 4.
Key Study Findings
Ragistomig, a bispecific antibody, is designed to deliver anti-PD-L1 activity combined with 4-1BB-driven T-cell activation. This dual mechanism aims to enhance anti-tumor efficacy while minimizing hepatotoxicity—an issue commonly associated with traditional 4-1BB agonists.
The Phase 1 trial's primary objectives were to establish the safety profile and dose-limiting toxicity of ragistomig monotherapy. Secondary goals included assessing the objective response rate (ORR), pharmacokinetics (PK), and immunogenicity. The study involved patients with advanced or relapsed/refractory solid tumors, particularly those treated previously with anti-PD(L)-1 therapies.
Encouraging Results
- The trial identified an optimal dose of 5 mg/kg, exhibiting dose-proportional pharmacokinetics.
- At this dose, the ORR was 25%, based on 3 partial responses (PR) out of 12 patients, with a median progression-free survival (PFS) of 15.6 weeks.
- The clinical benefit rate (CBR) was observed to be 75%, including 3 PRs and 6 instances of stable disease (SD).
- 71.4% of responders had relapsed or were refractory to prior anti-PD-(L)1 inhibitors.
- Notably, a complete response (CR) was achieved in one heavily pretreated patient with ovarian cancer at a 3 mg/kg dose.
Expert Insights
Raj Kannan, I-Mab's Chief Executive Officer, expressed optimism about ragistomig's potential, stating, "While immune checkpoint inhibitors have made significant strides in treating solid tumors, many patients do not respond or become refractory. Ragistomig offers a novel treatment alternative for these resistant cases. The initial data underscores our study's objectives, highlighting promising efficacy and safety, paving the way for further development."
Louie Naumovski, MD, PhD, Interim Chief Medical Officer for I-Mab, added, "The favorable safety profile, T-cell activation, and dose-proportional pharmacokinetics of ragistomig are encouraging. The 25% ORR and 75% CBR at the optimal dose underscore its potential, especially for heavily pretreated patients."
Future Directions
The promising initial results support the continued development of ragistomig. I-Mab plans to advance this clinical program, both as monotherapy and in combination with other treatments, in collaboration with ABL Bio.
The data will be detailed in a poster titled “Phase 1 trial Safety and Efficacy of Ragistomig, a Bispecific Antibody Targeting PD-L1 and 4-1BB in Advanced Solid Tumors” (Abstract #2529, Poster Board 8), available on June 1, 2024, from 9:00 a.m. to 12:00 p.m. CDT, presented by Dr. Gerald Falchook, Director of the Sarah Cannon Research Institute at HealthONE, Denver, Colorado.
About Ragistomig
Jointly developed with ABL Bio, ragistomig utilizes an Fc-silent anti-PD-L1 arm and a 4-1BB engaging antibody fragment to activate T-cells in the presence of PD-L1 expressing tumor cells. This design aims to reduce off-tumor toxicity while overcoming resistance to PD-(L)1 inhibition. Preclinical studies have shown superior anti-tumor activity compared to single agents. The ongoing Phase 1 study in the U.S. and South Korea seeks to further define its safety and efficacy profiles.
About I-Mab
I-Mab is a U.S.-based biotech company focused on developing innovative immunotherapies for cancer. The company has operations in Rockville, Maryland, and San Diego, California.
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