Why Is Cancer Focused MorphoSys Stock Trading Lower Today?

MorphoSys AG MOR released topline results from the Phase 3 MANIFEST-2 study investigating pelabresib, an investigational BET inhibitor, in combination with the JAK inhibitor ruxolitinib compared with placebo plus ruxolitinib in JAK inhibitor-naïve patients with myelofibrosis.

Myelofibrosis causes extensive scarring in the bone marrow, leading to severe anemia. Bone marrow scarring can also cause a low number of blood-clotting cells called platelets, which increases the risk of bleeding. Myelofibrosis often causes an enlarged spleen (acts like a blood filter).

The study met its primary endpoint, as the combination therapy demonstrated a statistically significant and clinically meaningful improvement in the proportion of patients achieving at least a 35% reduction in spleen volume (SVR35) at week 24 (66% on pelabresib vs. 35% on placebo and ruxolitinib), nearly doubling SVR35 response rates.

The key secondary endpoints assessing symptom improvement - the proportion of patients achieving at least a 50% reduction in total symptom score (TSS50) and absolute change in total symptom score (TSS) from baseline at week 24 - showed a strong positive trend favoring the pelabresib and ruxolitinib combination but did not meet statistical significance (p=0.0545).

TSS was reduced by 15.99 points at week 24, from 28.26 at baseline, in the pelabresib and ruxolitinib treatment arm and by 14.05 points at week 24, from 27.36 from baseline, in the placebo plus ruxolitinib arm.

In intermediate-risk patients, TSS was reduced by 15.18 points at week 24, from 28.20 at baseline, in the pelabresib and ruxolitinib treatment arm versus 12.74 points at week 24, from 27.53 at baseline, in the placebo plus ruxolitinib arm, which was significant. 

MorphoSys plans to submit a New Drug Application for pelabresib in combination with ruxolitinib in myelofibrosis to the FDA and a Marketing Authorization Application to the European Medicines Agency in the middle of 2024. 

Price Action: MOR shares are down 20.14% at $4.68 during the premarket session on the last check Tuesday.