Study summary

One CAR T-cell infusion brought major improvement to most people with severe myositis

CASTLE trial (myositis group) · 24 people (5 with myositis), phase 1/2 · Published January 2026, Nature Medicine

What was tested

Zorpocabtagene autoleucel, a CD19 CAR T-cell therapy, for treatment-resistant inflammatory myositis, lupus and systemic sclerosis, given once after stopping all other immune drugs.

What they found

• 4 of 5 people with myositis had a major or moderate response at 24 weeks.
• All patients stayed off steroids and other immune drugs.
• No severe cytokine release or neurotoxicity.

What it means

Supports the "immune reset" approach now in several myositis CAR T trials.