---
title: "Beam Therapeutics’ BEAM-302 Hits Protective AAT Levels in AATD; 60 mg Picked for Pivotal in H2 2026"
type: "News"
locale: "zh-CN"
url: "https://longbridge.com/zh-CN/news/280514152.md"
description: "Beam Therapeutics presented updated data from its Phase I/II study of BEAM-302, a gene therapy for alpha-1 antitrypsin deficiency (AATD). The study involved 29 patients, showing that a 60 mg dose achieved protective AAT levels above 11 micromolar. The therapy demonstrated significant reductions in mutant Z-AAT and maintained efficacy during inflammation. The safety profile was favorable, with no serious adverse events reported. Beam plans to advance BEAM-302 into pivotal development in H2 2026, based on the compelling data supporting its efficacy and safety."
datetime: "2026-03-25T18:13:12.000Z"
locales:
  - [zh-CN](https://longbridge.com/zh-CN/news/280514152.md)
  - [en](https://longbridge.com/en/news/280514152.md)
  - [zh-HK](https://longbridge.com/zh-HK/news/280514152.md)
---

> 支持的语言: [English](https://longbridge.com/en/news/280514152.md) | [繁體中文](https://longbridge.com/zh-HK/news/280514152.md)


# Beam Therapeutics’ BEAM-302 Hits Protective AAT Levels in AATD; 60 mg Picked for Pivotal in H2 2026

-   MarketBeat Week in Review – 3/4 – 3/8

Beam Therapeutics NASDAQ: BEAM executives and clinical collaborators presented updated top-line data from the company’s ongoing Phase I/II study of BEAM-302, an in vivo base-editing therapy being evaluated in patients with alpha-1 antitrypsin deficiency (AATD). The call focused on efficacy and safety results from 29 treated patients as of a February 10, 2026 data cutoff, along with the company’s plans to advance the program into pivotal development.

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## Updated clinical dataset and study design

CEO John Evans said Beam now has a “compelling and robust data set” from 29 AATD patients treated with BEAM-302 and believes the results support moving the program into pivotal development. Chief Medical Officer Dr. Amy Simon outlined the trial structure, noting the dose-escalation portion includes two parts: Part A enrolling patients with lung disease, followed by Part B enrolling patients with mild to moderate liver disease with or without AATD-associated lung disease.

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As of the cutoff date, Beam had treated patients across multiple cohorts, including single-dose cohorts of 15 mg, 30 mg, 60 mg, and 75 mg, as well as a multi-dose cohort evaluating two 60 mg doses eight weeks apart. The company also reported initial Part B results, including a 30 mg cohort and a 60 mg cohort where only one patient was efficacy evaluable at the cutoff.

## Efficacy: AAT increases, Z-AAT reduction, and corrected protein composition

Beam emphasized that BEAM-302 is designed to correct the PiZ mutation in the SERPINA1 gene in liver cells using an adenine base editor delivered via lipid nanoparticles (LNPs). The goal is to increase circulating alpha-1 antitrypsin (AAT) above the protective threshold of 11 micromolar, reduce mutant Z-AAT, and preserve physiologic regulation of AAT as an acute phase reactant.

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In the single-dose 60 mg cohort (six patients with follow-up out to 12 months), Beam reported a steady-state mean total AAT level of 16.1 micromolar, with all patients maintaining mean steady-state total AAT above 11 micromolar. In the 75 mg cohort (nine patients with follow-up out to nine months), the company reported a steady-state mean total AAT of 14.4 micromolar. Dr. Simon said functional activity was supported by a neutrophil elastase inhibition assay, and the company suggested the similar fold-change between 60 mg and 75 mg was consistent with “near saturation editing” at doses of 60 mg or higher.

Beam also reported durable and substantial reductions in mutant Z-AAT in the highest-dose cohorts, with approximately 80% reduction at steady state compared to baseline. Protein composition shifted strongly toward corrected MAAT:

-   **60 mg single dose:** 94% MAAT, with an approximately 84% reduction in mutant Z-AAT cited by Evans (and 80% reduction at steady state described by Simon)
-   **75 mg single dose:** 91% MAAT

In Part B patients with AAT-related liver disease, the company said efficacy trends were similar. In the Part B 30 mg cohort (three patients), steady-state mean total AAT was 12.5 micromolar with 75% MAAT and a 51% reduction in Z-AAT. In the single efficacy-evaluable Part B 60 mg patient, steady-state mean total AAT was 17.2 micromolar with 95% MAAT and an 86% decrease in Z-AAT.

In the multi-dose cohort (two 60 mg doses), Beam reported mean total AAT of 16.5 micromolar at day 84 (28 days after the second dose), with an 80% mean Z-AAT reduction and 93% MAAT.

## Evidence of inducibility during inflammation

Beam highlighted what it described as strong evidence that corrected AAT production remains inducible under normal physiologic regulation. In a Part A patient treated with a single 60 mg dose, the patient’s total AAT rose from a steady-state level of roughly 16 micromolar to approximately 30 micromolar during a respiratory infection, coinciding with elevated C-reactive protein (CRP). Importantly, AAT composition remained stable at about 94% MAAT before, during, and after the infection, and levels trended back down as the infection resolved.

Evans characterized this as a key differentiator from augmentation therapy, which delivers static AAT levels via weekly infusions and does not reproduce the natural acute phase response.

## Safety profile and dose selection for pivotal development

Dr. Simon said BEAM-302 was “well-tolerated” in the 26 patients treated with single-dose BEAM-302 from 15 mg to 75 mg. She reported no serious adverse events, dose-limiting toxicities, or grade 3 or higher adverse events in those single-dose cohorts. The most common events were grade 1 asymptomatic transient ALT and AST elevations within the first 28 days, along with grade 1 and grade 2 infusion-related reactions that resolved within a day.

In the multi-dose cohort, Beam observed a higher rate of events after the second dose. One patient experienced grade 4 ALT and grade 3 AST increases that were asymptomatic and resolved without treatment; another patient had a grade 2 ALT increase that also resolved without treatment. No bilirubin increases or clinical signs of liver dysfunction were observed. In Q&A, Simon said the rapid onset and resolution, alongside cytokine increases, suggested an inflammatory response to the second “load of lipid,” and she emphasized the company had not seen similar events with single dosing at higher doses.

Based on safety and efficacy, Beam selected **60 mg as the optimal biological dose** for a pivotal cohort the company expects to initiate in the **second half of 2026**.

## Regulatory and next steps

Company leadership said Beam has reached alignment with the U.S. Food and Drug Administration on a potential accelerated approval pathway for BEAM-302. President Giuseppe Ciaramella said Beam anticipates enrolling approximately **50 additional patients** in an expansion of the ongoing Phase I/II study to support a future biologics license application, with a primary endpoint expected to be based on AAT biomarkers evaluated over 12 months.

During Q&A, Simon added that the pivotal cohort is expected to require evidence of emphysema (for example by CT scan), while patients may or may not have liver disease. She also said the company is using an LC-MS assay for total AAT because it is preferred by FDA and enables measurement of AAT composition (MAAT versus Z-AAT), whereas turbidimetry does not provide composition.

Dr. Jeffrey Teckman of Saint Louis University provided a clinical overview of AATD and underscored unmet need, noting that current augmentation therapy is burdensome and does not address liver disease or restore the acute phase response. Teckman said achieving a carrier-like profile could eliminate “95% of the risk,” and he characterized the updated BEAM-302 data as “pretty exciting.”

## About Beam Therapeutics NASDAQ: BEAM

Beam Therapeutics, Inc NASDAQ: BEAM is a biotechnology company dedicated to developing precision genetic medicines through its pioneering base editing platform. Headquartered in Cambridge, Massachusetts, with additional research facilities in Philadelphia, the company focuses on engineering molecular editors capable of making precise single-nucleotide changes in DNA. By harnessing its proprietary base editing technology, Beam aims to correct or disrupt disease-causing genetic variants at their source, offering the potential for novel therapies in areas with significant unmet medical need.

Founded in 2017 as a spin-out from Harvard University and the Broad and Whitehead Institutes, Beam was co-founded by leading academic researcher David R.

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