bluebird bio Announces Posting of Briefing Documents for Upcoming FDA Advisory Committee Meeting

June 9 discussion will focus on eli-cel for the treatment of early active cerebral adrenoleukodystrophy in patients without a matched sibling donor and overall safety of lentiviral vector (LVV) gene therapy

June 10 discussion will focus on beti-cel for the treatment of β-thalassemia in patients who require regular red blood cell transfusions

bluebird bio, Inc. (NASDAQ: BLUE) (“bluebird bio” or the “Company”) today announced that the U.S. Food and Drug Administration (FDA) posted briefing documents for the FDA Cellular, Tissue and Gene Therapies Advisory Committee Meeting to review elivaldogene autotemcel (eli-cel) for early active cerebral adrenoleukodystrophy (CALD) in patients without a matched sibling donor and betibeglogene autotemcel (beti-cel) for the treatment of people with β-thalassemia who require regular red blood cell transfusions.

The advisory committee meeting will take place June 9-10, 2022. Briefing materials, agendas and webcast information for the meeting can be accessed here. The Company is not responsible for the content of, nor the statements made in, the briefing materials that were prepared by the FDA.

The Prescription Drug User Fee Act (PDUFA) goal dates for a decision on approval of beti-cel for people with β-thalassemia who require regular red blood cell transfusions and eli-cel for patients with early active CALD without a matched sibling donor are August 19, 2022, and September 16, 2022, respectively.

About elivaldogene autotemcel (eli-cel)

eli-cel (pronounced ELL-ee-cell) uses ex-vivo transduction with the Lenti-D lentiviral vector (LVV) to add functional copies of the ABCD1 gene into a patient’s own hematopoietic stem cells (HSCs). The addition of the functional ABCD1 gene allows patients to produce the ALD protein (ALDP), which is thought to facilitate the breakdown of very long-chain fatty acids (VLCFAs). The expression of ALDP and effect of eli‑cel is expected to be life-long. The goal of treatment with eli-cel is to stop the progression of CALD and, consequently, preserve as much neurological function as possible, including the preservation of motor function and communication ability. Importantly, with eli-cel, there is no need for donor HSCs from another person.

bluebird bio’s clinical development program for eli-cel includes the completed pivotal Phase 2/3 Starbeam study (ALD-102) and the ongoing Phase 3 ALD-104 study, which has completed enrollment and treatment of all patients. Additionally, bluebird bio is conducting a long-term safety and efficacy follow-up study (LTF-304) for patients who have received eli-cel for CALD and completed two years of follow-up in ALD-102 or ALD-104. Clinical studies of eli-cel were placed on hold by the FDA and follow-up of all patients continues, per protocol.

In ALD-102, 90.6% (29/32) of patients met the primary endpoint of Major Functional Disabilities (MFD)-free survival at 24 months. As previously reported, two patients withdrew from ALD-102 at investigator discretion, and one additional subject experienced rapid disease progression early after treatment, resulting in MFDs and subsequent death. All patients who completed ALD-102 enrolled in a long-term follow-up study (LTF-304). The median duration of follow-up is approximately four years (49 months; 13.4, 88.1 months).

Adverse reactions attributed to eli-cel observed in clinical trials include myelodysplastic syndrome, viral cystitis, pancytopenia, and nausea and vomiting. There have been no reports of graft-versus-host-disease, graft failure or rejection, transplant-related mortality, or replication-competent lentivirus in the 67 patients who received eli-cel and are being followed in clinical studies (ALD-102, ALD-104, LTF-304).

About betibeglogene autotemcel (beti-cel)

betibeglogene autotemcel (beti-cel) (pronounced BEH tee cell) is a one-time gene therapy custom-designed to treat the underlying cause of β-thalassemia in patients who require regular red blood cell (RBC) transfusions. beti-cel adds functional copies of a modified form of the β-globin gene (β^A-T87Q-globin gene) into a patient’s own hematopoietic (blood) stem cells (HSCs) in order to correct the deficiency of adult hemoglobin that is the hallmark of β-thalassemia. Once a patient has the β^A-T87Q-globin gene, they have the potential to produce beti-cel-derived adult hemoglobin (HbA^T87Q) at levels that may eliminate the need for transfusions. As of the data cut in August 2021, 89% (34/38) of evaluable patients in Phase 3 beti-cel studies achieved transfusion independence, which is defined as no longer needing RBC transfusions for at least 12 months while maintaining a weighted average Hb of at least 9 g/dL. These results were observed across all ages and genotypes, including pediatric patients as young as four years of age and those with the most severe (β⁰/β⁰) genotypes.

beti-cel is manufactured using the BB305 lentiviral vector (LVV), a third-generation, self-inactivating LVV that has been studied for more than a decade across two therapeutic areas.

Adverse reactions considered related to beti-cel were infrequent and consisted primarily of non-serious infusion-related reactions that occurred on the day of infusion (e.g., abdominal pain, hot flush, dyspnea, tachycardia and non-cardiac chest pain) and cytopenias (e.g., thrombocytopenia, leukopenia and neutropenia). One of these adverse reactions was a serious adverse event (SAE) of thrombocytopenia considered possibly related to beti-cel and has resolved.

The majority of AEs and SAEs in the beti-cel clinical development program were unrelated to beti-cel and largely reflect the known side effects of HSC collection and busulfan conditioning regimen (including several SAEs of veno-occlusive disease that resolved with treatment).

The Phase 3 Northstar-2 (HGB-207) and Northstar-3 (HGB-212) studies evaluating beti-cel are ongoing; enrollment is complete, and all patients have been treated. bluebird bio is also conducting a long-term follow-up study, LTF-303, to monitor safety and efficacy for people who have participated in bluebird bio-sponsored beti-cel clinical studies through 15 years post-treatment.

About bluebird bio, Inc.

bluebird bio is pursuing curative gene therapies to give patients and their families more bluebird days.

With a dedicated focus on severe genetic diseases, bluebird has industry-leading clinical programs for sickle cell disease, β-thalassemia and cerebral adrenoleukodystrophy and is advancing research to apply new technologies to these and other diseases. We custom design each of our therapies to address the underlying cause of disease and have developed in-depth and effective analytical methods to understand the safety of our lentiviral vector technologies and drive the field of gene therapy forward.

Founded in 2010, bluebird has the largest and deepest ex-vivo gene therapy data set in the world—setting the standard for the industry. Today, bluebird continues to forge new paths, combining our real-world experience with a deep commitment to patient communities and a people-centric culture that attracts and grows a diverse flock of dedicated birds.

For more information, visit bluebirdbio.com or follow us on social media at @bluebirdbio, LinkedIn, Instagram and YouTube.

bluebird bio is a trademark of bluebird bio, Inc.

Forward-Looking Statements

This press release contains “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995. All statements that are not statements of historical facts are, or may be deemed to be, forward-looking statements, including our statements regarding the Company’s plans and expectations for anticipated FDA approval of the BLAs for beti-cel and eli-cel. Such forward-looking statements are based on historical performance and current expectations about our future goals, plans and objectives and involve inherent risks, assumptions and uncertainties, including internal or external factors that could delay, divert or change any of them in the next several years, that are difficult to predict, may be beyond our control and could cause our future financial results, goals, plans and objectives to differ materially from those expressed in, or implied by, the statements. No forward-looking statement can be guaranteed. Forward-looking statements in this press release should be evaluated together with the many risks and uncertainties that affect bluebird bio’s business, particularly those identified in the risk factors discussion in bluebird bio’s Annual Report on Form 10-K, as updated by our subsequent Quarterly Reports on Form 10-Q, Current Reports on Form 8-K and other filings with the Securities and Exchange Commission. These risks include, but are not limited to: we may encounter additional delays in the development of our programs, including the imposition of new clinical holds or delays in resolving existing clinical holds, that may impact our ability to meet our expected timelines; the risk that the efficacy and safety results from our prior and ongoing clinical trials will not continue or be seen in additional patients treated with our product candidates; the risk that additional insertional oncogenic or other reportable events associated with lentiviral vector, drug product, or myeloablation will be discovered or reported over time; the risk that our eli-cel, beti-cel and lovo-cel programs may be subject to further delays in their development, including but not limited to the imposition of new clinical holds; the risk that eli-cel and/or beti-cel may not be approved within the priority review timeframe or at all; the risk that any one or more of our product candidates, including eli-cel and/or beti-cel, will not be successfully developed, approved or commercialized. The forward-looking statements included in this document are made only as of the date of this document and except as otherwise required by applicable law, bluebird bio undertakes no obligation to publicly update or revise any forward-looking statement, whether as a result of new information, future events, changed circumstances or otherwise.

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