Five Prime's Stock Quadruples On Positive Mid-Stage Stomach Cancer Study

Five Prime Therapeutics Inc FPRX shares are seeing astronomical gains Wednesday in reaction to a positive data readout.

What Happened: Bemarituzumab, a targeted therapy, in combination with FOLFOX6 chemotherapy, met all three efficacy endpoints in the Phase 2 study dubbed FIGHT in patients with fibroblast growth factor receptor 2b-positive, non HER2 positive, front-line advanced gastric or gastroesophageal junction cancer, the South San Francisco, California-based company said, citing topline results.

Among the three efficacy endpoints, median progression-free survival improved from 7.4 months to 9.5 months, median overall survival improved from 12.9 months, and the overall survival rate improved by 13.1%, the company said.

"These results bring us one step closer to the first potential targeted therapy for advanced gastric cancer in over a decade," said Helen Collins, Five Prime's Chief Medical Officer.

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Why It's Important Bemarituzumab is a therapeutic antibody targeting FGFR2b+ tumors that are found in about 30% of HER2-gastric cancers worldwide, Five Prime said.

"Trial results validate FGFR2b as a novel target for the third most common cause of cancer mortality worldwide and highlight development opportunities for other tumors that overexpress FGFR2b," Five Prime said in the release.

"The update is clearly a net positive and a big win for the stock amidst persistently low investor expectations," SVB Leerink analyst Jonathan Chang said in a note.

The analyst estimates peak U.S. sales of about $580 million in gastric and gastroesophageal junction cancer in 2030.

The company plans to complete a full evaluation of the available FIGHT Phase 2 data and work with investigators to share the results at an upcoming medical conference.

Five Prime also sees potential for bemarituzumab in other cancers, where FGFR2b is overexpressed.

The company is partnering with Zai Lab Ltd – ADR ZLAB for the development of the investigational asset in the Greater China region.

In premarket trading Wednesday, Five Prime shares were advancing 318% to $22.35.