Immusoft gave a glimpse on Monday at how the first patient to ever receive an engineered B cell therapy is doing nine months after being dosed, suggesting that the treatment has been safe so far and is showing early signs that it improved his disease.
The treatment is for mucopolysaccharidosis type I, or MPS I, a genetic disease in which a key enzyme needed to break down sugars is missing.
The adult patient in November received a low dose of Immusoft’s experimental treatment, ISP-001. He stayed on Sanofi’s Aldurazyme, an enzyme replacement therapy (ERT), for eight months and then was taken off ERT.
Immusoft has said its ultimate goal is to replace ERT, which requires long weekly infusions, with higher doses of its engineered B cell therapy, which it hopes will act as a protein factory for the body to replace the missing enzyme.
The company’s experimental treatment involves taking B cells from a patient and then programming them with non-viral gene delivery to make a key protein. The B cells are then returned to the patient in hopes that they will make that functional protein in the patient’s body. Notably, no preconditioning or immunosuppression was required for the B cell therapy.
Sean AinsworthThe first patient, who was treated at the University of Minnesota Medical Center, in the Phase 1 trial saw measures of complex sugars called GAGs in his urine fall in the normal range between three and eight months after treatment, which is not typically achieved on Aldurazyme alone. In an interview last week, Immusoft CEO Sean Ainsworth noted that none of the MPS I patients in Aldurazyme’s clinical trial who received the ERT reached normal urinary GAG levels.
The patient also saw a 25% decrease in heparan sulfate as measured in his cerebrospinal fluid at six months. Companies and patient advocacy groups have said the FDA has agreed that heparan sulfate is an acceptable surrogate measure of disease activity for MPS.
Beyond biomarker results, the patient also saw a 30% improvement in a six-minute walk test and increased range of shoulder motion at six months. Joint stiffness is a symptom of MPS I.
Ainsworth described the functional improvements as “unexpected,” noting the patient was given “the first and our lowest dose that we’ll be giving. And this was in an adult patient, so we didn’t think that there was much opportunity to reverse some of these manifestations.”
There have been no adverse events reported to date by the patient, according to Immusoft.
At nine months, one month after the ERT treatment had ended, the patient still saw an improvement on their six-minute walk test, though it was less than at six months. Meanwhile, the shoulder flexion improvement persisted.
The company is planning to dose a second adult patient in the study and is opening a second site at UCSF, where it also plans to enroll children.