Jean-Paul Kress’ words are coming back to haunt him. The MorphoSys CEO has previously said AbbVie “failed” its phase 3 myelofibrosis trial because the Big Pharma missed one of two endpoints. Now, Kress is defending MorphoSys’ similarly mixed data on its $1.7 billion rival.
The data come from a phase 3 clinical trial of pelabresib, a BET inhibitor that MorphoSys acquired in its $1.7 billion acquisition of Constellation Pharmaceuticals. The study tested the effect of giving pelabresib and the JAK inhibitor ruxolitinib to myelofibrosis patients. After 24 weeks, MorphoSys saw a significant improvement in the proportion of patients achieving at least a 35% reduction in spleen volume (SVR35).
That significant improvement caused the study to hit its primary endpoint. The problem for MorphoSys is that, until recently, management had consistently said a hit on the spleen volume endpoint was one of two outcomes needed to unlock the myelofibrosis market.
Pelabresib failed on the second key measure. The study found 52% of patients taking pelabresib and ruxolitinib had at least a 50% reduction in total symptom score (TSS50), compared to 46% of people who took placebo with the JAK inhibitor.
On a conference call with investors to discuss MorphoSys’ second-quarter results last month, Chief R&D Officer Tim Demuth, M.D., Ph.D., said the biotech knew “very well from interactions with agencies on both sides of the pond, namely FDA and EMA, what the approval endpoints are.”
“And that … is the 24-week landmark for SVR35 and TSS50,” Demuth added on the call.
Analysts have repeatedly asked MorphoSys about the importance of the two endpoints during recent calls and events, in part because AbbVie’s rival candidate navitoclax failed to improve TSS50. Kress was clear about what AbbVie’s TSS50 miss meant when he spoke to investors at a Morgan Stanley event in September, telling attendees that “they failed their phase 3 trial.”
But Kress struck a different tone in a postmarket statement yesterday to disclose MorphoSys’ own failure to improve TSS50, telling investors that he is “very pleased with this positive outcome” and outlining plans to file for approval in the U.S. and Europe around the middle of next year. The optimism is, in part, a reflection of MorphoSys’ analysis of the effect on TSS, an endpoint it added in September, and data on intermediate-risk patients.
Still, the TSS50 failure overshadowed those findings and the primary endpoint success, which found 66% of people on pelabresib and ruxolitinib met SVR35 compared to 35% of their peers who received placebo with the JAK inhibitor. Investors sent shares in MorphoSys down 24% on the Nasdaq to $4.42 in premarket trading from a Monday close of $5.86.