The serious and life-threatening infections experienced by those born with the rare immune disorder leukocyte adhesion deficiency-I mean that some babies don’t survive beyond infancy. Of those who do, most don’t make it past their fifth birthday. A Rocket Pharmaceuticals gene therapy for the disorder has clinical data showing that not only can it address the underlying genetic problem, it also helps patients live longer.
Rocket presented the preliminary data Thursday during the annual meeting of the American Society of Gene and Cell Therapy in Washington, D.C. Based on the results, the biotech said it is starting discussions with regulators and expects to submit applications seeking approvals in the first half of next year.
Severe leukocyte adhesion deficiency-I (LAD-I) is a rare, inherited immune disorder caused by mutations to ITGB2, the gene that encodes CD18, a protein that is important in helping white blood cells stick to blood vessels. Children born with LAD-I are more susceptible to recurrent bacterial and fungal infections that can become life-threatening. Antibiotics usually don’t work well for these patients and the infections that they develop require frequent hospitalizations. A hematopoietic stem cell transplant offers a curative treatment option, but the procedure comes with its own risks of life-threatening complications, which means it’s reserved only for the most severe cases.
Rocket’s gene therapy, RP-L201, is made with hematopoietic stem cells from the patient. Those cells are engineered with a lentiviral vector to carry a functional copy of the ITGB2 gene. Using a patient’s own stem cells avoids the need to find a matching donor, as is required with a hematopoietic stem cell transplant. This approach is also hoped to have less toxicity compared to a transplant with donor cells.
The open-label Phase 1/2 clinical trial enrolled nine children three months and older. Similar to the preparations required of a stem cell transplant, patients in the study needed to undergo a conditioning regimen to prepare their bodies to receive the experimental Rocket treatment. The main goal of the Phase 2 portion of the study is to measure the proportion of patients still alive one year after receiving the gene therapy as well as measuring the number of participants experiencing adverse events related to the treatment. Measuring CD18 expression is a secondary goal.
A Deep-dive Into Specialty Pharma
A specialty drug is a class of prescription medications used to treat complex, chronic or rare medical conditions. Although this classification was originally intended to define the treatment of rare, also termed “orphan” diseases, affecting fewer than 200,000 people in the US, more recently, specialty drugs have emerged as the cornerstone of treatment for chronic and complex diseases such as cancer, autoimmune conditions, diabetes, hepatitis C, and HIV/AIDS.
As of the March 9 cut-off date, Cranbury, New Jersey-based Rocket had data for patients ranging from three to 24 months of follow up after the infusion. The company reported that all nine patients showed sustainable CD18 expression on their neutrophils, a type of white blood cell. The median CD18 expression was 56%. For the seven patients that have reached the 12-month mark after infusion, overall survival is 100%. Furthermore, for all nine patients, Rocket reported a statistically significant reduction in hospitalizations. The company also said patients showed a resolution of skin rashes and restoration of wound repair capabilities.
Rocket reported no serious adverse events related to the therapy. The preconditioning regimen, which includes the chemotherapy busulfan, does come with side effects that include nausea, vomiting, and diarrhea. Rocket said that the adverse effects for these associated procedures are consistent with the safety profile of busulfan and preconditioning procedures.
“While allogeneic transplant options are available, they continue to be associated with considerable toxicity and today’s top-line safety and efficacy data point to the potential of RP-L201 to change the treatment paradigm for patients living with severe LAD-I,” Gaurav Shah, Rocket’s CEO, said in a prepared statement.
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