Surge of 111%! A Biotech Company Secures Rights to Jemincare's Anti-IgE Antibody

On December 23, 2024, RAPT Therapeutics announced it had acquired the global rights (excluding the Greater China region) to Jemincare's long-acting IgE antibody, JYB1904 (RPT904). RAPT will pay an upfront fee of $35 million, milestone payments up to $672.5 million, and a percentage of sales royalties, with a total deal value of $707.5 million. JYB1904 is currently in Phase II clinical trials in China.

This strategic collaboration aims to develop RPT904 into a potentially superior treatment compared to omalizumab, which is already approved for treating various allergic conditions as an anti-IgE monoclonal antibody. RAPT plans to first advance the development of RPT904 in the field of food allergies.

RAPT intends to initiate a Phase 2b clinical trial for RPT904 in food allergy treatment in the second half of 2025. The company noted the immense market opportunity in this field, especially since omalizumab was recently approved for food allergy treatment.

Following the announcement, RAPT Therapeutics' stock price soared by 111% on the same day, bringing its market capitalization to $608.3 million.

In addition, RAPT Therapeutics announced a $150 million private placement on Monday, expected to close around December 27.

About JYB1904 (RPT904)

JYB1904 is a next-generation, extended half-life anti-IgE monoclonal antibody designed to treat patients with food allergies, chronic spontaneous urticaria (CSU), and other allergic inflammatory diseases. RPT904 binds to free immunoglobulin E (IgE), a key driver of allergic diseases. Early clinical studies have shown that JYB1904 more than doubles the half-life compared to the first-generation anti-IgE monoclonal antibody omalizumab (Xolair), while enhancing pharmacokinetics and pharmacodynamics.

Jemincare completed a Phase I randomized, double-blind, single-ascending-dose study in China involving 56 healthy volunteers. The study primarily assessed the drug's safety, pharmacokinetics (PK), and pharmacodynamics (PD). Results showed JYB1904 was well-tolerated with a good safety profile, with all treatment-related adverse events being Grade 1 or 2. The pharmacokinetics of JYB1904 were approximately proportional to the dose, and the median half-life was more than twice that of omalizumab at the same dosage. The Phase I study also demonstrated that JYB1904 achieved a deeper and longer-lasting reduction of free IgE levels and a greater cumulative increase in total IgE compared to omalizumab at equivalent doses.

Jemincare is currently conducting two Phase II trials for JYB1904 in China:

1. Asthma Phase II Study: Focuses on comparing JYB1904's PK and PD profiles with omalizumab to determine dosing for future Phase III registration studies. Results are expected in the second half of 2025.
2. CSU Phase II Study: Evaluates the safety and efficacy of JYB1904, with results expected in the first half of 2026.