Menlo’s Serlopitant for Prurigo Nodularis Itching Flunks Two Phase III Trials


Menlo Therapeutics, based in Bridgewater, New Jersey, released topline results from two Phase III trials of once daily oral serlopitant for pruritus (itching) associated with prurigo nodularis (PN). Neither trial met their primary endpoint.

PN is a skin disease that results in hard, itchy nodules forming on the skin. The itching can be intense, with some patients scratching until they bleed or cause themselves pain. The scratching can cause more of the nodules to form.

Serlopitant is a small molecule, highly selective NK1-R antagonist. NK1-R is one of two receptors (the other is Substance P or SP), that are critical mediators of the urge to scratch. NK1-R stands for neurokinin-1 receptor, which is a naturally occurring peptide in the tachykinin neuropeptide family. Tachykinins have numerous functions in the nervous and immune systems.

Both trials’ primary endpoints were statistically significant reduction in pruritus compared to placebo based on a 4-point improvement responder analysis. In the MTI-105 study, 26.54% of patients receiving serlopitant had a 4-point or greater improvement on the worst-itch numeric rating scale (WI-NRS) at week 10 compared to baseline, compared to 20.31% in the placebo group.

In the other trial, MTI-106, 25.90% receiving serlopitant hit a 4-point or greater improvement in WI-NRS at week 10 compared to baseline versus 18.95% in the placebo group.

“Menlo undertook a robust Phase III program to investigate serlopitant as a potential treatment for pruritis associated with PN,” said David Domzalski, chief executive officer of Menlo. “While the data showed a numerical advantage for serlopitant compared with placebo on the primary endpoint, the difference was not statistically significant.”

He went on to say the company would thoroughly analyze the data to gain a better understanding of the outcome, but they don’t plan to continue studying the drug.

Domzalski indicated the company’s intention is to continue building its dermatology franchise and expand its pipeline. “We launched Amzeeq as a treatment for moderate-to-severe acne at the beginning of the year and are very encouraged by positive reception so far from both physicians and patients. FMX103, which is our 1.5% minocycline foam for the treatment of papulopustular rosacea, is currently under review at the FDA and has been assigned a target PDUFA action date of June 2, 2020. If approved, this product will be our second commercial launch in 2020.”

The company also has an ongoing Phase II trial for FCD 105, a combination product containing minocycline and the retinoid adapalene, which is expected to have a data readout in this quarter.

The company just completed its merger with Foamix Pharmaceuticals on March 9 of this year. Foamix is now a wholly owned subsidiary of Menlo. Foamix shareholders received 0.5924 shares of Menlo common stock for each Foamix share they held at the closing.

In addition, if one of the Phase III PN trials failed to meet the primary endpoint at or before May 31, 2020, Foamix shareholders would receive another 0.6815 of a share of Menlo common stock for each Foamix share. If both PN trials failed—which they did—Foamix shareholders would receive 1.2082 Menlo shares for each Foamix share, increasing pro forma ownership of the combined company of Foamix shareholders to 82%.

If both the PN trials had been success, no more Menlo shares would have been issued to Foamix shareholders and pro forma ownership by Foamix shareholders would have remained 59%.

Foamix received approval for Amzeeq in 2019 and launched it in January 2020. Foamix also submitted the New Drug Application for MFX103.

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