RIST-5122

Aristea Team/Courtesy Photo Due to safety concerns, Aristea Therapeutics announced Friday it is discontinuing the development of its Phase II lead program RIST4721. As a result, the San Diego-based biotech is also dissolving its business. After careful and extensive consideration and “exploring a range of strategic alternatives,” Aristea’s board decided that ending the company and its operations was a sound business decision, said James Mackay, Ph.D., president and CEO, Aristea, in a statement. Aristea launched in December 2018 as an AstraZeneca spin-out. The company dove into the biopharma space with $15 million in Series A backing to rehome molecules to develop novel treatments against severe inflammatory conditions. “Our aim here is to take molecules that have been discarded by big pharma for a variety of reasons, or from other biotechs who have taken them through preclinical development but are not equipped to take them into clinical,” Mackay told BioSpace in a January 2022 interview. Novo Holdings, the private limited liability company under the Novo Nordisk group, backed the startup. Aristea gained exclusive global rights to RIST4721, its lead asset, from AstraZeneca. The candidate is an antagonist of the CXCR2 protein and was set to enter Phase II assessments in palmoplantar pustulosis when the company launched. The company completed enrollment into this study in October 2019. Palmoplantar pustulosis is a recurrent inflammatory disorder characterized by flares of neutrophil-filled pustules on the palms and feet, causing pain, itching and burning sensations at these sites. RIST4721 intended to treat this condition by suppressing CXCR2, which is chiefly responsible for recruiting neutrophils at the site of inflammation. In July 2021, RIST4721’s potential attracted $63 million in Series B financing, which helped Aristea further advance the candidate through the clinic, build its leadership team and form new strategic partnerships. The Series B was again led by Novo Holdings, with new investors Arena Pharmaceuticals and Tekla Capital Management joining. Concurrent with the funding round, Aristea entered into a strategic collaboration with Arena Pharmaceuticals, a Pfizer unit, giving the latter the exclusive option to acquire Aristea and all its CXCR2 programs post-Phase II in exchange for $60 million upfront and $10 million in equity investments. However, in Friday’s announcement, Aristea revealed that safety concerns had snuffed out RIST4721’s promise. In an email to BioSpace, a company representative said they did not have additional information to provide regarding the safety concerns. By the time Aristea folded, RIST4721 was also being trialed for hidradenitis suppurativa, familial Mediterranean fever and Behcet’s disease. The company also developed RIST5122 and RIST8309, both CXCR2 antagonists, for undisclosed indications.