Antibody Drug Fails to Beat Placebo in Trial for Rare Inflammatory Skin Condition

AnaptysBio started the week with some disappointing news for its lead antibody drug imsidolimab. 

The drug, which is currently in studies for five other indications, was found to be no better than the placebo in a Phase II trial to treat moderate-to-severe palmoplantar pustulosis (PPP). The POPLAR trial did show the drug to be well tolerated with no serious or severe side effects. 

PPP is a rare, recurrent inflammatory disorder that presents itself as crops of sterile pustules that show up on one or both hands and feet. Patient's thickened, scaly, red skin easily develops painful cracks and may persist for many years. The disease is often seen in combination with plaque psoriasis, but it is yet to be determined if PPP is a variant of psoriasis. 

Fifty-nine patients at over 36 sites in North America and Europe were treated with monthly subcutaneous doses of imsidolimab for three months. The antibody inhibits the function of IL-36R for treating rare, inflammatory diseases. 

CEO Hamza Suria expressed disappointment over results and said, “Imsidolimab is currently being advanced in 5 other immuno-dermatology indications and we look forward to multiple additional clinical readouts during 2021 and 2022.” 

While the drug proved unsuccessful for PPP patients, Phase II results from GALLOP, a trial in patients with moderate-to-severe generalized pustular psoriasis (GPP) had more promising results. 

Granted Orphan Drug Designation by the FDA last July, imsidolimab was tested in eight patients. Two dropped out too early for results, but the other six all achieved a 54% improvement on a scale that incorporates both dermatological and systemic aspects of GPP.  

GPP is a life-threatening disease with no current approved therapies. A Phase III trial is anticipated for this indication in mid-2021.  

The expansion of the drug program is anticipated through this year and next for additional dermatological inflammatory trials including EGFRi-mediated skin toxicities, ichthyosis, hidradenitis suppurativa and acne. 

AnaptysBio is currently in a collaboration with GlaxoSmithKline in immuno-oncology efforts with the antibody drug dostarlimab. The team is looking forward to the commercial launch of the drug this year.  

The commercial launch may help bolster the biotech’s spiraling stock, which took a beating over these Phase II results. $ANAB stock dropped 35% before the markets even opened.