On January 15, 2021 Five Prime Therapeutics, Inc. (NASDAQ: FPRX) reported clinical results from the global, randomized, double-blind placebo-controlled Phase 2 FIGHT trial evaluating first-in-class targeted therapy bemarituzumab in advanced gastric or gastroesophageal junction (GEJ) cancer (Press release, Five Prime Therapeutics, JAN 15, 2021, View Source [SID1234574049]). Trial results were presented in a late-breaking oral presentation today by UCLA Health’s Zev Wainberg, M.D., at the 2021 ASCO (Free ASCO Whitepaper) Gastrointestinal Cancers Virtual Annual Symposium (ASCO GI). The ASCO (Free ASCO Whitepaper) GI presentation slides are available on the company’s website.

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The FIGHT trial evaluated bemarituzumab plus chemotherapy (mFOLFOX6) versus placebo plus chemotherapy in patients with fibroblast growth factor receptor 2b-positive (FGFR2b+), non HER2 positive frontline advanced gastric or GEJ cancer. The trial enrolled 155 patients in 15 countries across Asia, the European Union, and the United States, with 77 patients randomized to the bemarituzumab arm and 78 patients to the placebo arm.

The Phase 2 trial met all three efficacy endpoints and demonstrated statistically significant and clinically meaningful improvements in the primary endpoint of progression-free survival (PFS) and secondary endpoints of overall survival (OS) and overall response rate (ORR). Additional analysis showed a correlation between benefit and the percentage of FGFR2b+ tumor cells, confirming both the importance of the FGFR2b target and the activity of bemarituzumab against this target.

"Systemic chemotherapy is the standard of care for this deadly and aggressive form of gastric cancer. We are strongly encouraged by these data and the potential for a frontline targeted treatment that can improve overall survival," said Zev A. Wainberg, M.D., Associate Professor of Medicine at UCLA, Co-director of the Gastrointestinal Oncology Program and Director of Early Phase Clinical Research at the Jonsson Comprehensive Cancer Center. "The FIGHT trial results demonstrate that treatment with bemarituzumab in combination with chemotherapy can deliver a significant reduction in the risk of disease progression and death in gastric cancer patients whose tumors overexpress FGFR2b."

"The Phase 2 FIGHT clinical trial results validate our pioneering work on the role of FGFR2b overexpression in gastric cancer, and we’re excited about the implications of this new scientific understanding for other cancers," said Helen Collins, M.D., Five Prime’s Executive Vice President and Chief Medical Officer. "With these data in hand, we plan to continue to collaborate with regulatory agencies on next steps, initiate a global Phase 3 trial in gastric cancer and begin studying bemarituzumab in other epithelial cancers that overexpress FGFR2b."

The incidence of all grade adverse events was similar in the bemarituzumab and placebo arms of the study (100% vs 98.7%, respectively). Corneal events were reported more frequently in the bemarituzumab arm (67.1% vs 10.4%), with the most common corneal events in the bemarituzumab arm being dry eye (26.3%), keratitis (15.8%) and punctate keratitis (14.5%). Stomatitis (31.6% vs 13.0%) and elevated transaminases (34.2% vs 19.5%) were also more common in the bemarituzumab arm. Grade 3 and higher adverse events (82.9% vs 74.0%), serious adverse events (31.6% vs 36.4%) and deaths (6.6% vs 5.2%) were comparable across arms.

Ocular events are common in therapies targeting FGFR and were also reported in the FIGHT trial. More patients in the FIGHT trial discontinued bemarituzumab compared to placebo due to an adverse event (34.2% vs 5.2%), the majority (21 of 26 patients) due to an ocular event.

The discontinuation of bemarituzumab due to an ocular event decreased the median duration of exposure to bemarituzumab by 3.2 weeks; from 25.3 weeks (n=55, range: 2.0 to 71.7 weeks) to 22.1 weeks (n=21, range: 12.0 to 46.7 weeks).

In designing the Phase 3 trial, the company plans to incorporate findings from the FIGHT trial including baseline eye exams, prophylactic lubricating eye drops and close monitoring for signs and symptoms of corneal toxicity, including dry eye.

Five Prime Webcast /Conference Call Information

Five Prime Therapeutics will host a KOL conference call and live audio webcast following ASCO (Free ASCO Whitepaper) GI on Friday, January 15, 2021 at 4:30pm (EST) / 1:30pm (PST) to review the Phase 2 FIGHT clinical trial results and provide an update on the bemarituzumab program. The presentation will feature members of the Five Prime management team and Zev A. Wainberg, M.D., Associate Professor of Medicine at UCLA, Co-director of the Gastrointestinal Oncology Program and Director of Early Phase Clinical Research at the Jonsson Comprehensive Cancer Center, and an investigator in the trial.

To participate in the conference call, please dial (877) 878-2269 (domestic) or (253) 237-1188 (international) and refer to conference ID: 2063209. To access the live webcast please visit View Source

An archived copy of the webcast will be available on Five Prime’s website beginning approximately two hours after the conference call. Five Prime will maintain an archived replay of the webcast on its website for at least 30 days after the conference call.

About FGFR2b

The fibroblast growth factor (FGF)/fibroblast growth factor receptor (FGFR) pathway is implicated in the development and growth of cancer cells. FGFR2b is a splice form of FGFR which can be found in tumors of epithelial origin. Data from the FIGHT trial suggests that approximately 30 percent of patients with non HER2 positive gastroesophageal cancers overexpress FGFR2b.1 Five Prime and Roche Tissue Diagnostics have also found that FGFR2b is overexpressed in numerous other cancers, including squamous non-small cell lung cancer (NSCLC), triple negative breast cancer (TNBC), ovarian, pancreatic and intrahepatic cholangiocarcinoma.

About Bemarituzumab

Bemarituzumab (anti-FGFR2b) is a first-in-class targeted antibody that blocks fibroblast growth factors (FGFs) from binding and activating FGFR2b, inhibiting several downstream pro-tumor signaling pathways and potentially slowing cancer progression. Bemarituzumab is being developed in gastric and GEJ cancer as a targeted therapy for tumors that overexpress FGFR2b. The company is also evaluating the potential for bemarituzumab in other cancers that overexpress FGFR2b.

Five Prime granted an exclusive license to Zai Lab to develop and commercialize bemarituzumab in Greater China, and Zai Lab collaborated with Five Prime on the Phase 2 FIGHT trial in Greater China.

About Gastric Cancer and GEJ Cancer

Gastric cancer, also known as stomach cancer, is the third most common cause of cancer death worldwide and, excluding non-melanoma skin cancer, the fifth most common cancer worldwide, with over 1,000,000 new cases diagnosed each year.2 For HER2 negative patients, frontline therapy available today is the same systemic chemotherapy available since the 1990s.3,4