With Foamix Merger Weeks Away, Menlo Itching Drug Fails a Phase 2 Test

Xconomy San Francisco — 

A Menlo Therapeutics drug in testing for various itching conditions has failed a Phase 2 study, but executives say the results won’t translate to its lead itching target nor will they affect its pending merger with Foamix Pharmaceuticals.

The Menlo (NASDAQ: MNLO) drug, serlopitant, is an experimental treatment for pruritus, itching that’s associated with a number of disorders. The Phase 2 failure was in chronic pruritus of unknown origin. The goal for the 10-week, 233-patient study was to show a reduction in itching as assessed by a rating scale.

According to results released Wednesday, 37.9 percent of patients treated with serlopitant achieved a 4 point or greater improvement on the rating scale. But that was bested by the placebo group, where 39.3 percent of patients hit that mark. Furthermore, that placebo response was 10 percent higher than in any of the previous studies testing the once-daily pill, CEO Steve Basta said on a conference call to discuss the results. But Basta added that there’s no indication that this high placebo response would be duplicated in forthcoming Phase 3 tests of the drug in the Redwood City, CA, company’s lead indication, prurigo nodularis.

“That would be putting undue weight on the [chronic pruritus of unknown origin] results,” he said. “I think what you’ll see is this is an outlier.”

Serlopitant, a small molecule drug, was designed to block neurokinin 1 receptor, a nerve-signaling pathway for itching. In Phase 2 results for prurigo nodularis, a skin disorder that causes hard itchy lumps on the skin, Menlo reported that patients treated with the drug showed statistically significant improvement compared to those given a placebo. Basta said that prurigo nodularis is different in that the nodules and lesions that appear on the skin indicate the underlying cause of a patient’s itching. Chronic pruritus of unknown origin, by definition, has no explanation for the itching source. Itching experienced by this diverse group of patients may have different causes, which could explain the high placebo effect, Basta added.

The placebo effect has derailed other tests of serlopitant. Before achieving successful Phase 2 results in pruritus nodularis in 2018, the company reported two mid-stage failures, one addressing itching in atopic dermatitis and the other in treating chronic cough. Basta said he does not expect that research will continue in chronic pruritus of unknown origin, but further development of the compound in that indication and others will soon be in the hands of Foamix (NASDAQ: FOMX). Last fall the Israel-based skin drugs developer agreed to an all-stock merger with Menlo. In January, Menlo shareholders approved the transaction, which Basta said is now expected to close on or around March 9.

Speaking on the conference call, Foamix CEO David Domzalski said his company was aware that serlopitant was in proof-of-concept testing for chronic pruritus of unknown origin and that the focus of the merger was always around the drug’s potential in pruritus nodularis, Menlo’s lead indication. “Looking at the results we have today, our focus again is clearly on the [pruritus nodularis] program on a go-forward basis,” Domzalski said.

Foamix plans to pursue Phase 3 tests of serlopitant in patients with that condition, and if successful, file for FDA review by the end of this year. Assuming the drug is approved, Domzalski projected that Foamix could launch it late next year. Foamix is currently preparing to launch minocycline (Amzeeq), an antibiotic treatment for inflammatory lesions in patients who have moderate-to-severe acne. The FDA approved the topical treatment—a foam formulation of minocycline, an oral medication—in October. The company expects an FDA decision in June for FMX103, a minocycline foam tested as a treatment for rosacea.

Menlo isn’t the only company with disappointing pruritus news. Late Tuesday, Vanda Pharmaceuticals (NASDAQ: VNDA) reported a Phase 3 failure for its drug, tradipitant, in pruritus in adults with atopic dermatitis. Like Menlo’s drug, the experimental Vanda therapy is a small molecule designed to block neurokinin 1.

Despite the clinical trial failure, Vanda says the anti-itching effect of its drug was “robust” in patients who have mild atopic dermatitis, which represents 60 percent of the total atopic dermatitis population in the US. Those results will need to be confirmed by additional testing, and the Washington, DC-based company says it will determine its next steps after assessing results from a second Phase 3 test of the drug in atopic dermatitis. That study is ongoing.

Image: iStock/Tharakorn