On Thursday, Vertex Pharmaceuticals Incorporated (NASDAQ: VRTX ) announced results from its Phase 2 study of suzetrigine for painful lumbosacral radiculopathy (LSR), a disorder that causes pain in the lower back and hip that radiates down the back of the thigh into the leg.

The study met its primary endpoint with a statistically significant and clinically meaningful reduction in pain on the numeric pain rating scale (NPRS) .

The suzetrigine arm showed a statistically significant and clinically meaningful within-group reduction in pain from baseline, with a mean change in NPRS at Week 12 of -2.02.

Also Read: Vertex Has $5 Billion-Plus Opportunity In Pain And Kidney Disease Programs, Analyst Upgrades Stock

The study also included a placebo reference arm, which showed a similar within-group reduction in pain from baseline, with a mean change in NPRS at Week 12 of -1.98.

Secondary and other endpoints were consistent with the study’s primary endpoint.

Vertex also conducted post-hoc analyses showing variability in the placebo response across study sites, a recognized issue in pain trials.

In the ~40% of sites that had lower placebo responses, the suzetrigine arm within-group reduction in pain was similar to the overall study and had greater separation from the placebo arm.

These analyses suggest that trial design innovation may better control the placebo response and separate the treatment effect of suzetrigine from placebo in future studies, which Vertex will incorporate as it designs the pivotal program.

Suzetrigine was generally well tolerated in the study. William Blair notes that Vertex plans to move suzetrigine into Phase 3 trials following discussions with regulators despite Phase 2 results not clearly outperforming a placebo.

The analyst questions the decision, citing concerns about the trial’s design and the small effect size, which could make it hard to ensure success.

Price Action: VRTX stock is down 13.4% at $387.37 at last check Thursday.

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