2seventy bio : January 2023 Corporate Presentation

Unleash Time

2seventy bio company presentation

January 2023

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, manufacture or sale of our product candidates, including the design, initiation, enrollment and completion of pre-clinical and clinical studies; timelines for the results of ongoing and planned clinical trials for our product candidates and for ABECMA (ide-cel) in additional indications; the timing or likelihood of regulatory filings and acceptances and approvals thereof; expectations as to the market size for ABECMA and any other approved product we may successfully develop; the progress and results of our commercialization of ABECMA, including our goal of increasing manufacturing capacity and improving the manufacturing 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; anticipated 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; statements about the strategic plans for 2seventy bio and potential corporate development opportunities, including manufacturing expectations and benefits received from collaborations; statements about our ability to operate as a stand-alone company and execute our strategic priorities; and expectations regarding our use of capital, expenses and other future financial results, including our net cash spend, cash runway and U.S. net revenue for ABECMA in 2023. 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 successful 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 our plans with respect to the preclinical and clinical development and regulatory approval of our product candidates may not be successfully achieved on the planned timeline, 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 actual 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-Q 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 press release 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 the Company 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 the Company 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 information contained herein, or any other written or oral communication transmitted or made available to the you or your affiliates or representatives. The Company 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 omissions therefrom. This presentation shall not constitute an offer to sell or the solicitation of an offer to buy any securities, nor shall there be any sale of any securities in any state or jurisdiction in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such state or jurisdiction.

2

2seventy - At a Glance

BMS 50/50 US

$250-300M 2022 / $470-570M 2023*

Potential $2-3B US Peak

ABECMA

Commercial

ABECMA

Capacity Expansion

Predictable Delivery

ABECMA

Development

3rd Line K3 & FDA Submission

Front Line K9

ABECMA profitable in 2023

3	*US topline revenue, profit and loss shared 50/50 with BMS

Unleash Curative Potential of T cells

TIME

GEEKS

People & Culture

& Experience

Cash runway into 2025

Next Gen T cell Engineering Toolkit &

Clinical POC Insight Engine

Clinical Heme

B-NHL & AML

Horizon Dev

In-Vivo Editing (Novo)

In-Vivo CARs

Clinical Solid

MUC & More (REGN)

Suspension LVV Mftg

In-House Clinical DP Mftg (270-MPH)

Next Gen Mftg Improvements

410 employees

2023 Goals and Long-Term Drivers

Longer-Term Drivers

• Drive toward $2-3B ABECMA U.S. peak sales potential
• Path to profitability and sustainability
• Enabling partnerships
• Lever end-to-end cell therapy platform and capabilities
• Hire and retain the best & brightest

2023 Goals

Abecma

• Total US revenue $470-570M shared with BMS
• Present and publish KarMMa-3 data
• U.S. Approval in 3rd line
• Initiate KarMMa-9

Pipeline

• Data update for DARIC33 mid 2023
• Data update for bbT369 EOY 2023
• MUC16 IND EOY 2023
• MAGE-A4IIT EOY 2023 (JW)

Net cash spend of $180-220M

4

4

ABECMA® potential to be $2-3B market opportunity in US driven by label

expansion, increased capacity and double-digit market growth

2022

Launch and Lead

• Ongoing significant demand
• Increased capacity across supply chain
• RWE validates efficacy & safety even in the most difficult-to-treat populations
• KarMMa-3primary endpoint met in 3L+ MM
• Tracking to upper end of $250-$300M topline US revenue*

2023

Scale and Invest

• Further scale drug product mftg capacity
• Sustain high quality patient and provider commercial delivery
• Potential US approval in 3rd line+ MM; planning for initiation of NDMM KarMMa-9 study
• ABECMA sustainably profitable
• $470-570Mtopline US revenue

2024-2030+

Potential and Proof

• Expand supply chain to meet expanding patient potential
• Improve profit margins
• Gain approval in NDMM
• Drive towards $2-3B potential US peak sales

5	*US ABECMA profit and loss shared 50/50 between 2seventy and BMS as part of the collaboration agreement;
unaudited, based on information currently available and subject to change