Here’s a sentence you don’t hear often in cell and gene therapy: they re-dosed a patient. Safely. Eighteen months after the first treatment.
That’s Immusoft, a Seattle-based company that just landed a $15 million grant from the California Institute for Regenerative Medicine to expand clinical development of ISP-001, an autologous engineered B cell therapy for mucopolysaccharidosis type I. This is their second CIRM grant — the first was $8 million — bringing non-dilutive government funding alone to $23 million.
But the grant isn’t the story. The biology is.
Immusoft ISP platform — key milestones
Dec 2023 — First patient dosed
ISP-001 Phase 1 initiated in adult MPS I patients
Oct 2025 — First-ever safe re-dose
Patient re-dosed 18 months after initial treatment — a cell therapy first
1-year data
239-meter improvement in 6-minute walk test, meaningful pain reduction
Mar 2026 — $15M CIRM grant
Second CIRM award to expand clinical development
MPS I is a lysosomal storage disorder caused by a missing enzyme. Current treatment is enzyme replacement therapy — IV infusions, every week or two, for life. Immusoft’s approach is to take a patient’s own B cells, reprogram them using a non-viral transposon system to continuously produce the missing enzyme, and put them back. The B cells migrate to bone marrow, engraft, and essentially become permanent protein factories. No toxic chemo conditioning. No viral vectors. And critically — no immunosuppression.
That last part is why the re-dosing milestone matters so much. Most gene therapies are one-shot deals because the viral delivery triggers an immune response that blocks a second attempt. Immusoft’s non-viral approach apparently sidesteps that problem entirely. A second patient has been dosed at roughly three times the initial dose level with clean safety data.
The company also has a collaboration with Takeda — reportedly valued at up to $900 million — for delivering protein therapeutics across the blood-brain barrier to treat neurometabolic disorders. Plus ISP-002 for MPS II just received FDA Rare Pediatric Disease designation in January. For a company most people haven’t heard of, the pipeline is starting to stack up.
Watch for expanded clinical data as the new CIRM money flows in. If the re-dosing capability holds up across more patients, Immusoft isn’t just treating MPS I — they’re potentially rewriting the rules for how cell therapies can be administered.
The Biotech Voyager
Early-stage biotech signals, personalized.
The signals that matter to you — contextualized and written directly to you — so you cut through the noise and immediately understand why it matters.
