Shares in Menlo Therapeutics had dropped nearly 50% in pre-market trading as investors shrank back on news of a Phase III failure of serlopitant.

The company said that a once-daily, oral formulation of the drug failed to hit primary goals in patients with pruritus associated with prurigo nodularis (PN) in the Phase III MTI-105 and MTI-106 studies.

In both trials, serlopitant did not demonstrate a statistically significant reduction in pruritus in patients compared to placebo, but did show some numerical benefit.

In study MTI-105, 26.45% of patients in the serlopitant group achieved a 4-point or greater improvement on the worst-itch numeric rating scale, or WI-NRS, at week 10 compared to baseline versus 20.31% of patients treated with placebo.

In study MTI-106, 25.90% of patients in the serlopitant group achieved a 4-point or greater improvement on the WI-NRS at week 10 compared to baseline versus 18.95% of patients treated with placebo.

“While the data showed a numerical advantage for serlopitant compared with placebo on the primary endpoint, the difference was not statistically significant,” said David Domzalski, Menlo's chief executive.

“We will thoroughly analyse these data to better understand the outcome but, at this point, we do not intend to further pursue serlopitant,” he added.