Beam Therapeutics Presents Updated Clinical Data from the Phase 1/2 Trial of BEAM-302 in Alpha-1 Antitrypsin Deficiency (AATD) at the European Respiratory Society (ERS) Congress 2026
Updated BEAM-302 data show durable biomarker correction in AATD and support Beam’s move into a global pivotal cohort at the 60 mg dose.
Rhea-AI Summary
Beam Therapeutics (BEAM) reported updated Phase 1/2 data for BEAM-302 in alpha-1 antitrypsin deficiency (AATD) presented at the 2026 European Respiratory Society Congress.
As of August 17, 2026, 38 patients had received BEAM-302, with efficacy data presented from 29 single-dose patients across lung (Part A) and liver (Part B) cohorts. At the 60 mg dose, mean steady-state total AAT rose from 5.0 µM to 14.4 µM in Part A and from 4.7 µM to 13.5 µM in Part B, exceeding the 11 µM protective threshold, with functional AAT levels increasing dose-dependently and durably. Circulating mutant Z-AAT fell by 84% in both 60 mg cohorts, with corresponding reductions in toxic Z-polymers and dose-proportionate decreases in human neutrophil elastase activity.
Safety remained acceptable, with mostly mild-to-moderate infusion-related reactions in 41% of patients and transient liver enzyme elevations, including one Grade 3 ALT/AST event without bilirubin increase or treatment. Newly produced corrected M-AAT reached 93% of circulating AAT at steady state. Beam has begun dosing a global pivotal cohort using 60 mg and plans to pursue a U.S. accelerated approval pathway based on 12‑month AAT biomarker endpoints.
Positive
- Total AAT above protective 11 µM at 60 mg: 14.4 µM (Part A) and 13.5 µM (Part B) vs ~5 µM baseline
- Mutant Z-AAT reduced 84% in both Part A and Part B 60 mg cohorts
- Corrected M-AAT reached 93% of circulating AAT at steady state after 60 mg dosing
- HNE activity decreased in a dose-proportionate manner, with >80% of 60 mg Part A patients having at least one value below the lower limit of quantification
- Acceptable safety profile with mainly mild-to-moderate infusion reactions (41% of patients) and transient liver enzyme elevations
- Pivotal global cohort dosing started at 60 mg to support a planned U.S. accelerated approval based on 12‑month AAT biomarker endpoints
Negative
- 41% of patients experienced drug-related mild-to-moderate infusion-related reactions
- One patient had transient Grade 3 ALT/AST elevations after 60 mg dosing, indicating notable but reversible liver enzyme increase
News Explained
The pivotal BEAM-302 development program has begun dosing and is planned to add approximately 50 patients with AATD-associated lung disease, making the next-stage evidence package larger than the 29-patient dataset presented in this update.
Key Figures
- Patients treated
- 29 patients
- Single-dose dose-escalation data presented at ERS
- Infusion-related reactions
- 41%
- All patients; mild-to-moderate drug-related treatment-emergent adverse events
- Total AAT, Part A
- 14.4 µM mean; 15.2 µM median vs 5.0 µM baseline
- Single-dose 60 mg cohort
- Total AAT, Part B
- 13.5 µM mean; 13.8 µM median vs 4.7 µM baseline
- Single-dose 60 mg cohort
- HNE activity
- >80% of patients
- Part A 60 mg cohort had at least one measurement below quantification limit
- Z-AAT reduction
- 84%
- Reduction in circulating Z-AAT in Part A and Part B 60 mg cohorts
- M-AAT proportion
- 93%
- Steady-state proportion following 60 mg treatment in both cohorts
- Biomarker endpoint duration
- 12 months
- Primary endpoint under intended U.S. accelerated approval pathway
Previous Clinical trial Reports
-
Reported durable efficacy, reduced neutrophil elastase activity, and FDA accelerated-approval plans.
24h Move is the share-price change in the day after each event; other market factors may also have contributed.
Key Terms
pharmacodynamics medical
pharmacokinetics medical
accelerated approval regulatory
biologics license application regulatory
neutrophil elastase medical
AI-generated analysis. How Rhea-AI works. Not financial advice.
BEAM-302 Continues to Demonstrate Potential as One-time Treatment for Both Lung and Liver Manifestations of AATD, with AAT Protein Production Under Normal Physiological Control
With Up to 18 Months Follow-Up, Data Show Long-Term Durability of In Vivo Correction of Disease-causing Mutation with Single Dose of BEAM-302
Treatment with BEAM-302 Increased Total and Functional AAT and Decreased Neutrophil Elastase Activity in Circulation
BEAM-302 Led to Reduction in Circulating Mutant Z-AAT and Corresponding Decrease in Toxic Circulating Z-polymers
Safety Profile of BEAM-302 Remains Consistent with LNP-based Therapies
Dosing Underway in Global Pivotal Cohort Designed to Support Potential U.S. Accelerated Approval
Beam to Host Investor Webcast Today, September 8, 2026, at 7:00 a.m. ET
CAMBRIDGE, Mass., Sept. 08, 2026 (GLOBE NEWSWIRE) -- Beam Therapeutics Inc. (Nasdaq: BEAM), a biotechnology company developing precision genetic medicines through base editing, today announced updated clinical data from the Phase 1/2 trial evaluating BEAM-302 for alpha-1 antitrypsin deficiency (AATD). The data were presented in a late-breaking oral presentation at the European Respiratory Society (ERS) Congress 2026 in Barcelona, Spain. BEAM-302 is Beam’s lead liver-targeted genetic disease program and a potentially best- and first-in-class therapy designed to directly correct the root cause of AATD and address both liver and lung manifestations of disease.
“BEAM-302 is leading the way as a novel medicine that can potentially provide a genetic cure and treat both the lung and liver disease manifestations in patients living with severe AATD,” said John Hurst, M.D., Ph.D., professor at University College London and an investigator in the BEAM-302 trial. “The data presented today at ERS are promising and demonstrate that a single dose of BEAM-302 restored AAT function, as evidenced by an increase in total circulating AAT above the protective threshold, the new production of corrected, functional M-AAT, significant reduction in mutant Z-AAT, and, importantly, AAT remained under normal physiologic control during periods of inflammation when it is needed.”
BEAM-302 Phase 1/2 Clinical Trial Data Update
BEAM-302 is being evaluated in a Phase 1/2, open-label, dose exploration and dose expansion clinical trial to investigate its safety, tolerability, pharmacodynamics, pharmacokinetics and efficacy. Part A is designed to evaluate patients with AATD-associated lung disease, and Part B evaluates patients with mild to severe liver disease, with or without lung disease. As of August 17, 2026, 38 patients have been dosed with BEAM-302 across Part A and Part B. The presentation at ERS included data from 29 patients treated with a single dose of BEAM-302 in the dose-escalation portion of the study: Part A (15 mg, n=3; 30 mg, n=3; 60 mg, n=6; 75 mg, n=9) and Part B (30 mg, n=3; 60 mg, n=5). Data from patients in the multi-dose cohort (n=3) and the Part A expansion cohort (n=6) were not included.
As of the June 24, 2026, data cutoff date, treatment with single-dose BEAM-302 was well tolerated with an acceptable safety profile in both Part A and Part B cohorts. Mild-to-moderate infusion-related reactions (IRRs) were the most common drug-related treatment-emergent adverse events (TEAEs), occurring in
Treatment with BEAM-302 led to rapid and durable increases of total and functional AAT, decreases in mutant Z-AAT and toxic Z-polymers, and new production of corrected M-AAT. Data were consistent with topline results announced in March 2026. Key findings from 29 efficacy-evaluable patients as of the June 24, 2026, data cutoff date include:
- A single dose of BEAM-302 of 60 mg led to sustained increases in total AAT above the 11 µM protective threshold. After treatment with a single dose of 60 mg BEAM-302 in Part A, the steady-state1 circulating total AAT2 mean and median were 14.4 µM and 15.2 µM, respectively, compared to 5.0 µM at baseline. In the Part B 60 mg cohort, the post-treatment steady-state circulating total AAT mean and median were 13.5 µM and 13.8 µM, respectively, compared to 4.7 µM at baseline.
- Increased total AAT in circulation was functional. Functional AAT levels increased in a dose-dependent manner up to 60 mg and were durable through follow-up.
- Human neutrophil elastase (HNE) activity levels, another measure of AAT function, decreased in a dose proportionate manner with BEAM-302 treatment, with >
80% of patients in the Part A 60 mg cohort having at least one HNE activity measurement below the lower limit of quantification. - Mutant Z-AAT was significantly and durably reduced after treatment with BEAM-302, with an
84% reduction in circulating Z-AAT in both Part A and Part B 60 mg cohorts. - BEAM-302 also led to a significant decrease in circulating Z-AAT protein aggregates, referred to as Z-polymers, from baseline in the 60 mg cohort. Circulating Z-polymers have been shown to correlate with liver disease severity3 and to amplify lung inflammation4 by inducing neutrophil recruitment.
- Evidence of AAT protein production under normal physiologic control was observed during an upper respiratory tract infection in a patient in the Part A 60 mg cohort.
- Following treatment with BEAM-302, newly produced corrected M-AAT comprised the majority of AAT in circulation. The proportion of M-AAT at steady state was
93% following treatment with 60 mg in both Part A and Part B, exceeding the approximately80% M-AAT proportion associated with the MZ genotype.
“These data reinforce the potential of BEAM-302 to address AATD at its root cause by correcting the disease-causing mutation and restoring production of functional AAT needed to prevent lung and liver damage with a single treatment,” said Amy Simon, M.D., chief medical officer of Beam Therapeutics. “With our global pivotal cohort now dosing patients, we are building on our scientific and clinical leadership in the field as we advance the only genetic medicine in pivotal development for AATD. We believe BEAM-302 has the potential to transform the AATD treatment paradigm, and we are focused on bringing this one-time treatment to patients who have been waiting decades for more treatment options that can impact the spectrum of disease manifestations.”
BEAM-302 Pivotal Development
Based on feedback from the U.S. Food and Drug Administration (FDA), Beam intends to pursue an accelerated approval pathway for BEAM-302 based on a primary endpoint of AAT biomarkers evaluated over 12 months, with 60 mg as the selected dose. To support a future biologics license application (BLA) submission, the company anticipates enrolling approximately 50 additional patients with AATD-associated lung disease, with or without liver disease, in an expansion of the ongoing open-label Phase 1/2 trial. In July, Beam dosed the first patient in this global pivotal cohort.
Investor Webcast Information
Beam will host a conference call and webcast today, September 8, 2026, at 7:00 a.m. ET to review these updates. A live webcast of the presentation will be available under "Events" in the Investors section of the company's website at www.beamtx.com, and a replay will be available shortly after the event.
About BEAM-302
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 has the potential to further minimize lung inflammation and dysfunction. Importantly, because BEAM-302 corrects the native AAT gene in its normal genetic location, AAT levels have been observed to increase physiologically in response to infection and inflammation in treated patients. 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 has been durable to date in patients treated in Beam's clinical trial.
About Alpha-1 Antitrypsin Deficiency (AATD)
AATD is an inherited genetic disorder that can cause early onset emphysema and liver disease. The most severe and common 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 (
About Beam Therapeutics
Beam Therapeutics (Nasdaq: BEAM) is a biotechnology company committed to establishing the leading, fully integrated platform for precision genetic medicines. To achieve this vision, Beam has assembled a platform with integrated gene editing, delivery and internal manufacturing capabilities. Beam’s suite of gene editing technologies is anchored by base editing, a proprietary technology that is designed to enable precise, predictable and efficient single base changes, at targeted genomic sequences, without making double-stranded breaks in the DNA. This has the potential to enable a wide range of therapeutic editing strategies that Beam is using to advance a diversified portfolio of base editing programs. Beam is a values-driven organization committed to its people, cutting-edge science, and a vision of providing lifelong cures to patients suffering from serious diseases.
Cautionary Note Regarding Forward-Looking Statements
This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. Investors are cautioned not to place undue reliance on these forward-looking statements, including, but not limited to, statements related to: the therapeutic applications and potential of our technology, including with respect to AATD; our plans, and anticipated timing, to advance our AATD program; the clinical trial designs and expectations for BEAM-302; our pursuit of an accelerated approval pathway for BEAM-302 based on biomarker endpoints; our competitive position in the AATD treatment landscape; and our ability to develop lifelong, curative, precision genetic medicines for patients through base editing. Each forward-looking statement is subject to important risks and uncertainties that could cause actual results to differ materially from those expressed or implied in such statement, including, without limitation, risks and uncertainties related to: our ability to develop, obtain regulatory approval for, and commercialize our product candidates, which may take longer or cost more than planned; that the FDA may not agree to an accelerated approval pathway for BEAM-302 or may require additional data or studies; our ability to raise additional funding, which may not be available; our ability to obtain, maintain and enforce patent and other intellectual property protection for our product candidates; the uncertainty that our product candidates will receive regulatory approval necessary to initiate or continue human clinical trials; that preclinical testing of our product candidates and preliminary or interim data from preclinical studies and clinical trials may not be predictive of the results or success of ongoing or later clinical trials; that initiation and enrollment of, and anticipated timing to advance, our clinical trials may take longer than expected; that our product candidates, including the delivery modalities we rely on to administer them, may cause serious adverse events; that our product candidates may experience manufacturing or supply interruptions or failures; risks related to competitive products; and the other risks and uncertainties identified under the headings “Risk Factors Summary” and “Risk Factors” in our Annual Report on Form 10-K for the year ended December 31, 2025, our Quarterly Report on Form 10-Q for the quarter ended June 30, 2026, and in any subsequent filings with the Securities and Exchange Commission. These forward-looking statements speak only as of the date of this press release. Factors or events that could cause our actual results to differ may emerge from time to time, and it is not possible for us to predict all of them. We undertake no obligation to update any forward-looking statement, whether as a result of new information, future developments or otherwise, except as may be required by applicable law.
Contacts:
Investors:
Holly Manning
Beam Therapeutics
hmanning@beamtx.com
Media:
Josie Butler
1AB
josie@1abmedia.com
______________________________
1 Steady state is defined as the period beginning on a patient's Day 28 visit and lasting until that patient's last visit.
2 Circulating total AAT levels were measured using turbidimetry.
3 Mahadeva, Ravi et al. “Polymers of Z alpha1-antitrypsin co-localize with neutrophils in emphysematous alveoli and are chemotactic in vivo.” The American journal of pathology vol. 166,2 (2005): 377-86.
4 Mulgrew, Alan T et al. “Z alpha1-antitrypsin polymerizes in the lung and acts as a neutrophil chemoattractant.” Chest vol. 125,5 (2004): 1952-7.
FAQ
How many patients and which doses were included in the BEAM-302 efficacy analysis?
The efficacy analysis included 29 patients treated with a single dose of BEAM-302 in the dose-escalation portion: Part A lung disease cohorts at 15 mg (n=3), 30 mg (n=3), 60 mg (n=6) and 75 mg (n=9), and Part B liver disease cohorts at 30 mg (n=3) and 60 mg (n=5). Data from a multi-dose cohort (n=3) and the Part A expansion cohort (n=6) were not included in this update.
What evidence suggests BEAM-302-corrected AAT remains under normal physiologic control?
Evidence of AAT protein production under normal physiologic control came from a patient in the Part A 60 mg cohort who experienced an upper respiratory tract infection. During this inflammatory episode, AAT remained under normal physiologic regulation, increasing when needed, which the company views as consistent with preserved physiological control.
What is Beam Therapeutics’ planned regulatory path for BEAM-302?
Beam intends to pursue an accelerated approval pathway in the United States, using a primary endpoint of alpha-1 antitrypsin biomarkers measured over 12 months at the 60 mg dose. To support a future biologics license application, the company expects to enroll approximately 50 additional patients with AATD-associated lung disease, with or without liver disease, as an expansion of the ongoing open-label Phase 1/2 trial.
What were the main treatment-emergent adverse events observed with BEAM-302?
The most common drug-related treatment-emergent adverse events were mild-to-moderate infusion-related reactions, occurring in 41% of all patients. Transient and predominantly Grade 1 elevations of alanine transaminase (ALT) and/or aspartate aminotransferase (AST) were also seen. One Part B patient at 60 mg experienced transient Grade 3 ALT/AST elevations without bilirubin increases and did not require treatment.
How does BEAM-302 affect toxic Z-polymers associated with AATD?
In the 60 mg cohort, BEAM-302 treatment led to a significant decrease in circulating Z-AAT protein aggregates, known as Z-polymers, from baseline. These Z-polymers have been reported to correlate with liver disease severity and to amplify lung inflammation by inducing neutrophil recruitment.
How can investors access Beam’s webcast discussing the BEAM-302 data?
Beam will host a conference call and webcast on September 8, 2026, at 7:00 a.m. ET to review the BEAM-302 updates. A live webcast will be available under the “Events” section in the Investors area of the company’s website at www.beamtx.com, and a replay will be accessible shortly after the event.