Key Takeaways
- Genmab’s Rina-S shows a 50% unconfirmed response rate in advanced endometrial cancer, surpassing analyst expectations.
- The biotech acquired Rina-S during its $1.8 billion takeover of ProfoundBio and has since expanded its market potential to over $2 billion.
- Genmab plans to initiate a Phase 3 trial for Rina-S by the end of 2025, building confidence with no significant adverse effects reported.
First Data on Rina-S in Endometrial Cancer
Genmab has announced promising initial data on rinatabart sesutecan (Rina-S) in patients with advanced endometrial cancer. The biotech company reported an unconfirmed response rate of 50%, outperforming expectations set by analysts at William Blair. This news enhances confidence in Rina-S as it approaches Phase 3 trials.
Acquired last year through a $1.8 billion deal with ProfoundBio, Rina-S is a folate receptor alpha (FRα)-directed antibody-drug conjugate (ADC) that was initially under investigation for ovarian cancer in a Phase 1/2 trial. Following further research, Genmab has identified multiple potential indications, raising the overall valuation for Rina-S to more than $2 billion.
Endometrial cancer is considered a significant opportunity for Rina-S, making the release of this initial clinical data a critical step in Genmab’s ambitious plans for the ADC. Ahead of the upcoming American Society of Clinical Oncology (ASCO) Annual Meeting, Genmab revealed that response rates in lower and higher dose cohorts were recorded at 50% and 45.5%, respectively, with two complete responses observed in the lower dose group. Approximately 80% of the responses remain ongoing at the time of the cutoff, and patients had previously undergone one to eight lines of therapy before enrolling in the trial.
During an earnings call earlier this month, Chief Medical Officer Tahamtan Ahmadi discussed current treatment strategies for advanced endometrial cancer, which typically include a combination of chemotherapy and checkpoint inhibitors. These shifts in the standard of care, coupled with the absence of a control group in Genmab’s study, complicate the interpretation of outcomes. Nonetheless, Ahmadi highlighted historical contexts to underscore the significance of the current results. He remarked that response rates for second-line therapies often hover between 10% to 15%, putting Rina-S’ performance into perspective.
With William Blair analysts suggesting that a response rate exceeding 30% would be indicative of a successful program, Genmab’s achievement of a 50% rate has fueled greater confidence in the upcoming Phase 3 trial set to commence by the end of 2025. Notably, the trial reported no instances of ocular toxicity, neuropathy, or interstitial lung disease, further bolstering Genmab’s case for Rina-S.
Genmab positions endometrial cancer as a proving ground for Rina-S, aiming to demonstrate its efficacy across a range of folate receptor alpha expressions. This strategy is key to establishing Rina-S as a superior alternative to AbbVie’s Elahere, another ADC targeting the same receptor. However, AbbVie has initiated legal action against Genmab, alleging that the company has been “willfully blind” to the theft of trade secrets regarding Rina-S.
Overall, the encouraging data for Rina-S not only strengthens the company’s commitment to developing innovative cancer therapies but also positions it competitively within a rapidly evolving landscape of treatments.
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