Updated version 1 - Artiva to halt cell therapy and lay off 94% of staff after the deaths of two patients

Updated share price information and added analyst comments in points 5 and 6

Reuters, October 27 - Artiva Biotherapeutics (ARTV.O) said on Tuesday that it will suspend development of its experimental cell therapy for certain autoimmune diseases, which is its main candidate drug, after the deaths of two patients. Following the news, its share price plunged 32%.

The company said it will cut about 94% of its workforce and evaluate strategic options.

Details are as follows:

• Artiva’s therapy AlloNK was being tested in a mid-stage clinical trial as a potential treatment for autoimmune diseases such as rheumatoid arthritis

• The company said one patient in the trial experienced a fatal neurological event after treatment

• The company stated that investigators and an independent safety review committee assessed that the event was most likely related to complications caused by the chemotherapy drug fludarabine

• Artiva added that another patient in the trial died suddenly about two months after starting treatment, and researchers assessed that this event was unrelated to AlloNK

• “The two patient deaths, combined with diminished durability of efficacy, have quickly turned what seemed to be a promising and differentiated path of development into one of excessive risk and uncertainty,” said Cantor Fitzgerald analyst Josh Schimmer

• Schimmer said that continuing to advance the AlloNK program would face serious challenges and require very high capital costs

• As of September 30, Artiva held approximately $319.1 million in cash, cash equivalents, and investments

• According to its annual report, as of December 31, 2025, the company had 104 full-time employees

(For the convenience of non-native English speakers, Reuters has automated the translation of its report into several other languages. As automation may result in errors or lack necessary context, Reuters does not guarantee the accuracy of the translated text, which is provided purely for reader convenience. Reuters accepts no liability for any damages or losses arising from the use of the automated translation service.)