Rare diseases were a key focus on the third day of the J.P. Morgan Healthcare conference, with several companies presenting updates on their progress and plans for 2026.
Rocket Pharmaceuticals CEO Gaurav Shah described 2026 as a “year of execution, year of excitement” for the company. Rocket faced challenges in 2025, including withdrawing its biologics license application for gene therapy mozafancogene autotemcel for Fanconi Anemia due to business reasons and initiating cost-cutting measures. In May, the FDA placed a hold on Rocket’s pivotal Phase II trial of RP-A501 for Danon disease after a patient death.
Shah said that Rocket intends to resume dosing patients in its Danon disease program in the first half of this year. He stated that RP-A501 has shown “strong durability,” including in two patients who have been followed for more than five years. “All our patients in the Phase I trial, adults as well as pediatric, continue to flourish beyond the age where they would typically demonstrate heart failure,” Shah added.
The company plans to dose three patients in early 2026 before consulting with the FDA about further study steps. “We have no indication that there will be any change, but there may be additional patients that are added,” Shah said.
Rocket is also awaiting an FDA decision by March on its gene therapy Kresladi for severe leukocyte adhesion deficiency-I. The therapy was previously rejected due to manufacturing concerns. Shah said, “We hope to move from a late-stage clinical stage company to a commercial-stage gene therapy company.”
REGENXBIO is another company active in rare diseases. Its Hunter syndrome gene therapy clemidsogene lanparvovec is under regulatory review with an action date set for February 8. CEO Curran Simpson called this period “a really pivotal year for us.” He noted there has not been a new treatment for Hunter syndrome in two decades.
Simpson also discussed upcoming milestones: REGENXBIO expects Phase III results from its Duchenne muscular dystrophy program RGX-202 in the first half of this year and data from ABBV-RGX-314 (for wet age-related macular degeneration) later this year through its partnership with AbbVie. Simpson stated, “we’re gearing up . . . for commercial readiness.”
Replimune addressed developments regarding its oncolytic immunotherapy RP1 following last year's surprise FDA rejection for advanced melanoma use. CEO Sushil Patel highlighted durable responses seen with RP1 and noted feedback from physicians seeking new options for difficult-to-treat patients. Patel said over 1,000 patients have received RP1 so far and emphasized readiness to launch if approved by April 10.
Replimune is also exploring use of RP1 beyond skin cancer into deeper tissues like liver and lung, reporting encouraging initial results with response rates similar or higher than those seen previously.
Kyverna Therapeutics presented updates on mivocabtagene autoleucel (miv-cel), which targets stiff-person syndrome (SPS), a rare neurological autoimmune disorder affecting fewer than 5,000 people in the U.S., characterized by painful spasms and muscle stiffness. CEO Warner Biddle stated: “We want to deliver the first autoimmune CAR T in the neuroinflammation space.” Kyverna’s pivotal Phase II study of miv-cel is currently 40% enrolled; approval filing is planned this year.
Biddle explained: “We’re the only CAR T company in the autoimmune space with a fully humanized CD19, CD28 co-stimulatory domain with the potential for differentiated safety and differentiated efficacy.” Recent data showed a median improvement of 46% in mobility among SPS patients—a result analyst William Blair described as exceeding expectations.
Kyverna is also developing miv-cel therapies targeting myasthenia gravis and lupus nephritis; relevant clinical data are expected later this year.
