RemeGen Announces Phase I/II Results for Novel Antibody-Drug Conjugate RC88

RemeGen Co., Ltd., a commercial-stage biotechnology firm, announced the findings of their pioneering Phase I/II study on RC88, an antibody-drug conjugate (ADC) designed to target mesothelin (MSLN)-expressing advanced solid tumors. The study results were presented at the American Society of Clinical Oncology Annual Meeting (ASCO 2024) in Chicago. Professor Liu Yutao from the Chinese Academy of Medical Sciences Cancer Hospital led the presentation, focusing on the drug's efficacy and safety in treating ovarian cancer, non-squamous non-small cell lung cancer (NSCLC), and cervical cancer.

RC88, developed by RemeGen, is a first-in-class ADC that specifically targets MSLN, a protein overexpressed in various solid tumors but limited in normal tissues. The drug comprises a recombinant humanized anti-MSLN monoclonal antibody linked to monomethyl auristatin E (MMAE), a microtubule inhibitor. This combination allows RC88 to selectively bind to and attack MSLN-overexpressing tumor cells, resulting in cell death through G2/M arrest and apoptosis. Preclinical studies have demonstrated RC88's capacity to deliver its cytotoxic payload effectively to MSLN-expressing cells, showing significant antitumor activity and a manageable safety profile.

The Phase II study enrolled patients with MSLN-expressing advanced solid tumors who had not responded to standard treatments. Key endpoints included overall response rate (ORR), disease control rate (DCR), progression-free survival (PFS), and safety. By February 21, 2024, the study had enrolled 170 patients. Following dose escalation, the study moved to Phase II with doses of 2.0 mg/kg and 2.5 mg/kg administered every three weeks.

In the ovarian cancer cohort, 54 patients with high MSLN expression participated. Among the 31 patients in the 2.0 mg/kg group, who had undergone multiple prior treatments, the ORR was 45.2%, and the confirmed ORR (cORR) was 41.9%. The median duration of response (DoR) was 8.02 months. Notably, 61.1% of these patients had previously received bevacizumab, and 51.9% had been treated with PARP inhibitors (PARPi).

The NSCLC cohort included 16 efficacy-evaluable patients with EGFR/ALK wild-type mutations. The ORR and cORR were 31.3% and 25%, respectively. Among patients with high MSLN expression, the ORR was 41.7%, the cORR was 33.3%, the median PFS was 6.87 months, and the median DoR was 9.13 months.

The cervical cancer cohort had 18 patients who had progressed despite previous systemic therapies. The ORR and cORR in this group were 33.3% and 27.8%, respectively. Among patients who had received at least two prior lines of therapies, the ORR was 41.7%, and the cORR was 33.3%.

Dr. Fang Jianmin, CEO of RemeGen, highlighted the significance of these findings, noting that the current standard chemotherapy for ovarian cancer has an ORR of just 12%. The promising 41.9% ORR observed with RC88 suggests notable potential for improving patient outcomes in MSLN-expressing advanced solid tumors. Dr. Jianmin emphasized RemeGen's commitment to advancing innovative therapies to meet significant unmet medical needs and improve patient care.

RemeGen, founded in 2008, is a leading Chinese biopharmaceutical company dedicated to addressing unmet clinical needs in autoimmune, oncology, and ophthalmic diseases. The company operates research labs and offices in China and the United States, focusing on discovering, developing, and commercializing innovative biologic drugs of significant clinical value. RC88 is a testament to their ongoing efforts to develop groundbreaking treatments for life-threatening illnesses.