Faced with safety issues over inflammation drug, AstraZeneca spinout Aristea closes shop

Confronted with safety findings, Aristea Therapeutics is not only canning work on its mid-stage inflammatory program but has decided to dissolve the business entirely.

Things seemed to be going well for Aristea as recently as last November, with the biotech taking on board a crop of clinical experts as it looked to expand its pipeline. The company’s lead asset, a CXCR2 antagonist dubbed RIST4721, was undergoing phase 2 trials for four neutrophil-mediated diseases: a rare inflammatory disorder called palmoplantar pustulosis (PPP), a painful skin condition called hidradenitis suppurativa, a genetic disorder called familial Mediterranean fever and Behcet's disease, which causes inflammation of the blood vessels.

But safety findings from the phase 2 trials have blown up those plans, the company revealed in a bombshell announcement this morning. Aristea didn’t go into details of the specific safety signals or which trials they had been observed in.

Whatever they were, the findings were significant enough that the San Diego-based biotech “has discontinued the RIST4721 development program in order to protect patient safety.” With that decision goes any hopes of keeping the business up and running.

"Although the decision to discontinue the RIST4721 development program is disappointing for the Aristea Therapeutics team and patients in need of new treatment options, we believe it is absolutely the right decision to protect patient safety, which must always be paramount in drug development," CEO James Mackay, Ph.D., said in the release. "The board's decision to dissolve Aristea Therapeutics was reached after exploring a range of strategic alternatives and is a sound business decision." 

The news may be felt all the way up at Pfizer’s headquarters. The Big Pharma had acquired the option to take over the biotech after it bought Arena Pharmaceuticals at the tail end of December 2021. That deal came six months after Arena had stumped up funding for Aristea as part of a collaboration to push RIST4721 through the clinic. Once the therapy completed the phase 2 trial in PPP, Arena—and later Pfizer—had the option to buy Aristea outright.

At the time, analysts also saw potential in RIST4721 as a PPP treatment. There are no treatments specifically for the condition—which causes blisterlike sores to form on the palms of the hands and soles of the feet. Patients use topical steroids, moisturizers or ultraviolet light therapy to ease symptoms. Aristea’s drug was designed to tackle PPP at the source by dialing down CXCR2, a receptor that plays a role in recruiting neutrophils, or white blood cells, to areas of inflammation.

Aristea is only the latest in a string of biotech closures in the opening weeks of this year, a reflection of the tough climate that the industry still faces. February alone has already seen Magenta Therapeutics wind down in the wake of a patient death as well as Vyant Bio announce that it's reached the end of the road.