Beam Therapeutics Inc, a biotechnology company developing precision genetic medicines through base editing, today announced that the United States (U.S.) Food and Drug Administration (FDA) has granted Regenerative Medicine Advanced Therapy (RMAT) designation to BEAM-302, a liver-targeting lipid-nanoparticle (LNP) formulation of a guide RNA and an mRNA encoding a base editor designed to correct the disease-causing mutation in patients with alpha-1 antitrypsin deficiency (AATD). AATD is an inherited genetic disorder that affects the lungs and/or liver, leading to early onset emphysema and liver disease, and for which there is significant unmet need for effective therapies that can treat the entire spectrum of disease.

“Just weeks after the clearance of our U.S. investigational new drug application, we are pleased to report that the FDA has now granted RMAT designation to BEAM-302, recognizing its potential as a transformative, one-time treatment for patients living with AATD,” said Giuseppe Ciaramella, Ph.D., president of Beam Therapeutics. “This designation underscores the strength of our clinical data to date and the promise of base editing to directly correct the genetic mutation that is the root cause of most cases of severe AATD. With RMAT designation enabling closer and more frequent collaboration, we look forward to working with the FDA to accelerate the development of BEAM-302 and bring this potentially curative therapy to AATD patients as safely and swiftly as possible.”

The FDA’s RMAT designation is designed to support the development and evaluation of regenerative medicines, including genetic therapies, with the intention of addressing serious or life-threatening diseases that have unmet medical needs. RMAT designation provides opportunities for early interactions with the FDA to discuss potential surrogate or intermediate endpoints to support accelerated approval, organizational commitment from senior staff at the agency, opportunities to participate in novel review and development programs, and the potential for a rolling review and priority review of a product’s future biologics license application.

Positive initial safety and efficacy data from the Phase 1/2 trial of BEAM-302 were previously reported in March, establishing clinical proof of concept as a potential treatment for AATD and in vivo base editing. Preliminary results from the first three single-ascending dose cohorts in Part A of the study demonstrated that BEAM-302 was well tolerated, with single doses of BEAM-302 leading to durable, dose-dependent correction of the disease-causing mutation and total AAT protein levels above the therapeutic threshold in the 60 mg dose cohort. Beam has initiated dosing in the fourth cohort of Part A, evaluating 75 mg of BEAM-302, and expects to report updated data at a medical conference in the second half of 2025. Additionally, the company plans to dose the first patient in Part B, which will include AATD patients with mild to moderate liver disease, in the second half of 2025 as well. Beam previously announced the clearance of the U.S. investigational new drug (IND) application for BEAM-302 for the treatment of AATD in March 2025.      

BEAM-302 is a liver-targeting lipid-nanoparticle (LNP) formulation of base editing reagents designed to correct the PiZ mutation. Patients homozygous for this mutation (PiZZ) represent the majority of patients living with severe AATD disease. A one-time A-to-G correction of the PiZ mutation with Beam’s adenine base editor has the potential to simultaneously reduce the aggregation of mutant, misfolded AAT protein that causes toxicity to the liver (Z-AAT), generate therapeutic levels of corrected protein (M-AAT), and increase total and functional AAT in circulation, thereby addressing the underlying pathophysiology of both the liver and lung disease. In addition, the reduction in circulating PiZ aggregates (i.e., polymers) has the potential to further minimize lung inflammation and dysfunction. Importantly, because the native AAT gene would be corrected in its normal genetic location, AAT levels are anticipated to increase physiologically in response to inflammation or infection. This is a critical aspect of AAT’s normal function to regulate the body’s inflammatory response, which does not occur with currently approved protein replacement therapies. Correction of the PiZ mutation is expected to be durable based on preclinical and clinical evidence.

AATD is an inherited genetic disorder that can cause early onset emphysema and liver disease. The most severe form of AATD arises when a patient has a point mutation in both copies of the SERPINA1 gene at amino acid 342 position (E342K, also known as the PiZ mutation or the “Z” allele). This point mutation causes alpha-1 antitrypsin, or AAT, to misfold, accumulating inside liver cells rather than being secreted, resulting in very low levels (10%-15%) of circulating AAT. In addition to resulting in lower levels, the PiZ AAT protein variant is also less enzymatically effective compared to wildtype AAT protein. As a consequence, the lung is left unprotected from neutrophil elastase, resulting in progressive, destructive changes in the lung, such as emphysema, which can result in the need for lung transplants. The mutant AAT protein also accumulates in the liver, causing liver inflammation and cirrhosis, which can ultimately cause liver failure or cancer requiring patients to undergo a liver transplant.

It is estimated that approximately 100,000 individuals in the U.S. have two copies of the Z allele, known as the PiZZ genotype, although only about 10% of all patients are thought to have been diagnosed. There are currently no curative treatments approved for patients with AATD, and the only approved therapy in the U.S., intravenous AAT protein replacement, has not been shown to prevent ongoing lung function decline and destruction in patients.

Source: beamtx.com