Another Phase 3 flop for FibroGen as DMD drug fails to improve mobility

FibroGen, Negative trial data, pamrevlumab, Duchenne muscular dystrophy

FibroGen’s troubles continue to mount. The biotech announced its fourth phase 3 failure in four months after the market closed on Tuesday, showing no benefit of its Duchenne muscular dystrophy (DMD)  drug candidate over placebo in a second trial, further sinking its prospects.

The DMD drug candidate, pamrevlumab, is an anti-CTGF antibody that FibroGen hoped would have multiple applications based on its anti-fibrotic mechanism. The San Francisco-based biotech launched several late-stage trials of pamrevlumab in different indications, ranging from muscle wasting to cancer survival. However, the first batch of results has been disappointing.

In June, pamrevlumab failed to meet its primary endpoints in phase 3 trials in non-ambulatory DMD and idiopathic pulmonary fibrosis. These failures came after a major clinical setback for FibroGen’s oral anemia drug roxadustat.

Now, FibroGen has reported another failure of pamrevlumab in ambulatory DMD patients. The phase 3 trial enrolled 73 boys aged 6 to 12 years with ambulatory DMD and randomized them to receive pamrevlumab or placebo on top of systemic corticosteroids.

After 52 weeks, there was no difference between the pamrevlumab and placebo groups on the North Star Ambulatory Assessment, a measure of motor abilities. The placebo-adjusted mean difference of -0.528 was not statistically significant, leading to the miss of the primary endpoint. Pamrevlumab also did not improve any of the secondary endpoints that assessed mobility in different ways.

“We are deeply disappointed that the LELANTOS-2 study did not meet its primary endpoint. We are grateful for the courageous efforts of patients, their caregivers, the advocacy community, and the trial investigators who have contributed to this important clinical study. We are committed to sharing all learnings from this trial with the Duchenne community and hope that there are insights that may help future efforts to develop treatments for this devastating disease.”

– Thane Wettig, Interim Chief Executive Officer, FibroGen

FibroGen’s stock price plunged 22% to $1 in premarket trading, continuing a trend that has erased 95% of the value of the company in six months. Despite the value-destroying setbacks, the biotech still has a chance to salvage pamrevlumab. In the first half of next year, FibroGen is expected to release data from two phase 3 trials of the antibody in different pancreatic cancer settings.

The biotech has enough cash to pivot to its early-stage oncology pipeline even if its advanced assets go up in flames. With $361 million in hand at the end of June, FibroGen plans to share phase 1 data on its CD46-targeting antibody-drug conjugate by the end of the year and file to study two other assets in humans next year.

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