Sometimes even an apparently successful clinical trial may not be enough to save your drug—or your stock price—once you dig into the numbers.
That’s what Ventyx Biosciences found when it reviewed data from a phase 2 trial of TYK2 inhibitor VTX958 in moderate to severe plaque psoriasis. The San Diego-based biotech reported that the two higher doses, 225 mg and 300 mg, of the four that were assessed hit the study’s primary endpoint of showing a statistically significant proportion of patients who experienced a 75% reduction in the Psoriasis Area and Severity Index at Week 16 compared to placebo.
But on looking more closely at the data, Ventyx concluded that “the magnitude of efficacy observed did not meet our internal target to support advancement of VTX958 in plaque psoriasis.”
As a result, the company is ending both its phase 2 plaque psoriasis trial as well as a separate midstage study of the drug in psoriatic arthritis. A further phase 2 trial of VTX958 in Crohn’s disease will continue to enroll patients for the time being, ahead of an interim efficacy analysis planned for the first quarter of next year.
Investors didn’t take kindly to the news, sending Ventyx’s stock plunging 73% in premarket trading Tuesday to $3.77 from a Monday closing price of $14.09.
“While the phase 2 trial of VTX958 in plaque psoriasis met the primary and key secondary endpoints, we are disappointed by the magnitude of efficacy observed, despite having achieved target levels of drug exposure in the trial,” CEO Raju Mohan, Ph.D., said in the third-quarter earnings release.
“Although these results do not support further development of VTX958 in the highly competitive psoriasis and psoriatic arthritis indications, I want to thank the patients and investigators for their participation,” Mohan added.
Ventyx has three other candidates in the clinic, including a S1P1R modulator called VTX002 which had positive results last month from a phase 2 trial in ulcerative colitis. Also in a midstage trial is the peripheral NLRP3 inhibitor VTX2735, which is being assessed in patients with familial cold autoinflammatory syndrome.
VTX002 faced a similar problem to VTX958 last month, hitting the primary endpoint in a phase 2 trial without resolving investors’ doubts over whether it will have an edge over rival S1P1 modulators like Pfizer’s etrasimod and Bristol Myers Squibb’s approved Zeposia.