Prolium Bioscience Raises $50M in Series A Funding to Advance Autoimmune Therapy Pipeline

Prolium Bioscience walked into the biotech arena like it already knew the ending of the story. Quiet launch, then boom, $50M on the table and patients already being dosed. That kind of sequencing tells you something about the mindset in the room. The science moves first, the capital follows the signal. Congratulations to Scott Requadt and the team at Prolium Bioscience for bringing serious momentum to a field that has been waiting for sharper tools.

The $50M Series A comes courtesy of founding investor RTW Investments, one of those firms that tends to show up where the real science lives. When RTW backs something early, they are not buying lottery tickets. They are betting on biology that can punch above its weight. Peter Fong and the RTW crew know the autoimmune battlefield well, and this investment says they believe Prolium Bioscience has a weapon worth carrying.

At the center of it all is PRO-203, a bispecific CD20xCD3 T cell engager designed to hunt down the B cells that drive some of the nastiest autoimmune diseases on the planet. Think systemic sclerosis. Think severe lupus with lupus nephritis. Not easy problems. Not forgiving ones either. PRO-203 works by binding CD20 on B cells and CD3 on T cells, essentially introducing the immune system to itself and saying, politely but firmly, handle your business.

And the science is not sitting in a slide deck waiting for a conference stage. Healthy volunteers are already being dosed in a single ascending dose study. 5 patients with treatment refractory lupus and lupus nephritis have already received PRO-203 in an investigator initiated study. Earlier oncology trials in China showed a 59% complete response rate and an 82% overall response rate in relapsed or refractory non Hodgkin lymphoma. Those numbers tend to make people stop scrolling.

Prolium Bioscience also secured global rights to PRO-203 in non oncology indications and oncology rights outside Asia from KeyMed Biosciences and InnoCare Pharma, giving the company room to run where autoimmune disease is still starving for better answers. The next move is already lined up. A multinational Phase 1/2 study in systemic sclerosis is expected to begin in the second quarter of 2026.

Biotech has a rhythm. Discovery. Risk. Conviction. Capital. Then the long stretch where data either whispers or roars. Right now Prolium Bioscience is stepping onto that stage with $50M in fuel, a serious T cell engager, and a clinical program already in motion. The immune system is complicated. Sometimes it just needs the right introduction.