2seventy bio : Corporate Presentation April 2024

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2seventy bio company presentation

April 2024

Cautionary note regarding forward-looking statements

These slides and the accompanying oral presentation may contain "forward -looking statements". These statements include, but are not limited to: statements about our plans, strategies, timelines and expectations with respect to the development and commercialization of ABECMA (ide-cel); timelines for the results of ongoing and planned clinical trials for ABECMA in additional indications; the timing or likelihood of regulatory filings and acceptances and approvals thereof; expectat ions as to the market size for ABECMA; the progress and results of our commercialization of ABECMA, including our goal of increasing manufacturing capacity and improving the man ufacturing process and the number of patients that

are expected to be treated with ABECMA in the commercial setting and potential late line global revenue for ABECMA; anticipat ed revenues resulting from sales of ABECMA; statements about the efficacy and perceived therapeutic benefits of our product candidates and the potential indications and market opportunities therefor; and expectations regarding

our use of capital, expenses and other future financial results, including our net cash spend and cash runway. Any forward -looking statements in this presentation are based on management's current expectations and beliefs and are subject to a number of risks, uncertainties and important factors that may cause actual events or results to differ materially from those expressed or implied by any forward-looking statements contained in this presentation, including, without limitation, the risk that the market opportunities for our approved

product or any future approved product are smaller than we believe they are; the risk that BMS, upon whom we rely for the suc cessful development and commercialization of ABECMA does not devote sufficient resources thereto, is unsuccessful in its efforts, or chooses to terminate its agreements with us; the risk that we and/or BMS or our third party vendors will be

unable to increase manufacturing and supply capacity for ABECMA; the risk that our BLAs, sBLAs and INDs will not be accepted for filing by the FDA on the timeline that we expect, or at all; the risk that ABECMA will not be as commercially successful as we may anticipate; and the risk that we are unable to manage our operating expenses or cash use for

operations. For a discussion of other risks and uncertainties, and other important factors, any of which could cause our actu al results to differ from those contained in the forward- looking statements, see the section entitled "Risk Factors" in the information statement contained in our most recent Form 10 -K and most recent quarterly reports any other filings that we have made or will make with the Securities and Exchange Commission in the future. All information in this presentation is as of the date of the release, and 2seventy bio

undertakes no duty to update this information unless required by law. This presentation has been prepared by 2seventy bio for the exclusive use of the party to whom 2seventy bio delivers this presentation. This presentation does not constitute an offer to sell or the solicitation of an offer to buy any securities of the Company. The information contained herein is for informational purpose, and may not be relied upon in connection with the purchase or sale of any security. Neither 2seventy bio nor any of its affiliates or representatives makes any representation or warranty, expressed or implied, as to the accuracy or completeness of this presentation or any of the i nformation contained herein, or any other written or oral communication transmitted or made available to the you or your affiliates or representatives. 2seventy bio and its affiliates and representatives expressly disclaim to the fullest extent permitted by law any and all liability based, in whole or in part, on the presentation or any information contained herein or any other written or oral communication transmitted or made available to you or your affiliates or representatives, including, without limitation, with respect to errors therein or omis sions therefrom.

Unlocking Abecma Value in 2024

First-in-class CAR T treatment for 4L+ r/r multiple myeloma

$358M total US commercial revenue in 2023

Prepared to launch Abecma in earlier lines, if approved, in partnership with BMS

Regeneron asset purchase agreement and strategic realignment

Closed April 2024

Completed asset purchase agreement with Regeneron: sold oncology and autoimmune research and development programs

2seventy focused exclusively on development and commercialization of Abecma, creating path to financial sustainability

New company structure and leadership aligns with

go-forward business needs; streamlined team of ~60 employees

including Quality and small G&A group

Transaction maximizes value for shareholders and best positions assets to deliver for patients

ABECMA Poised for a Comeback

Today

Reset and Return to Growth

• • Prepared to meet demand upon potential approval in 3L+

• • Educate on safety and efficacy profile with RWE

• • Educate on treatment sequencing

Prove and Execute

• • Build on growth in 3L+ setting following potential 2024 launch

• • Growing body of RWE reinforcing Abecma's differentiated safety and efficacy

• • Execute KarMMa-9 study in NDMM

2028 - 2030+

Long Term Future

• • Potential approval in NDMM following completion of KarMMa-9 study

• • Build on 7+ years of RWE to solidify Abecma position within MM treatment landscape

*US ABECMA profit and loss shared 50/50 betw een 2seventy and BMS as part of the collaboration agreement

ABECMA real world experience shows consistent outcomes with the KarMMa pivotal study despite sicker patient population

• • Several large global studies show ABECMA efficacy in the real world is consistent with the KarMMa study

• • Many RWE patients across all studies would not have met the eligibility criteria for KarMMa

• • Safety data similar to KarMMa with no new safety signals; limited Parkinsonism and Guillain-Barre and low non-relapse mortality*

Hansen et al, J Clin Oncol (2023), Sidana et al, oral presentation 1027 ASH 2023; Cayla et al, abstract 2139 ASH 2023

*Source: FAERS database. RWD analyses are observational in nature and reflect data outside of the controlled clinical trial s etting. These analyses are not tested for statistical significance and are not intended to be compared to clinical trial data

KarMMa-3 results and planned KarMMa-9 front-line study have the potential to drive label expansion into broad U.S. market opportunity

Addressable U.S. Patients on ABECMA label over time

Key questions informed by ASH 2023 data

• • KarMMa-2c data demonstrate potential of Abecma to deliver frequent, deep and durable responses in patients with inadequate response to front line ASCT.

• • After median FU of 39.4 months, all patients who received maintenance with lenalidomide are still in response.

• • OS confounded by patient-centric design which allowed for crossover. Imbalance in early deaths driven by patients untreated with ide-cel.

• • No difference between Abecma and SOC in ITT; when adjusted for crossover, OS favors Abecma arm

• • Significant PFS benefit over standard of care in heavily pretreated, triple class exposed patient population

• • Importance of bridging therapy, especially in high risk patients

• • BMS driving rapid expansion of site footprint, education on real world evidence and treatment sequencing.

• • Educating market on Abecma's consistent safety and competitive efficacy profile

KarMMa-2c

➤

KarMMa-2 cohort 2c

KarMMa-2c: Deepened responses in patients with inadequate response to frontline ASCT (<>

Lenalidomide maintenanceNolenalidomidemaintenance

DAYS ON STUDY

The bar starts at month 2, day 1 (equiv alent to 1 month post ide-cel inf usion) and continues to later of last response assessment date or data cutof f date (May 3, 2023). Response was def ined as ≥ PR based on IMWG criteria by inv estigator assessment.

D, day ; LEN, lenalidomide; M, month.

• • All treated patients alive at data cut-off with median FU of 39.4 months; no new safety signals

• • ORR: 87.1%; CRR: 77.4%

• • At 36 months, DOR was 80.9% and PFS was 76.8%

• • Of the 8 patients that received lenalidomide maintenance, progression events have not been observed

CR/s CR

VGPR

PR

MINIMAL RESPONSESTABLE DISEASE PD

LEN MaintenanceOngoing

Rodríguez-Otero P, et al. ASH 2023 Abstract 1028

10