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Forward-Looking Statements

This communication contains forward-looking statements related to Gilead Sciences, Inc. (“Gilead”), Arcellx, Inc. (“Arcellx”) and the acquisition of Arcellx by Gilead that are subject to risks, uncertainties and other factors. All statements other than statements of historical fact are statements that could be deemed forward-looking statements, including all statements regarding the intent, belief or current expectation of Gilead and Arcellx and members of their respective senior management teams. In some cases, forward-looking statements can be identified by the use of words such as “anticipate,” “believe,” “estimate,” “expect,” “intend,” “seek,” “may,” “plan,” “project,” “should,” “target,” “will,” or the negative of these terms or other similar expressions, although not all forward-looking statements contain these words. Forward-looking statements include, without limitation, statements regarding the transaction and related matters, prospective performance and opportunities, post-closing operations and the outlook for the companies’ businesses, including, without limitation, the timing of the expected commercial launch of anito-cel and Gilead’s ability to streamline preparation for launch the potential efficacy and safety profile of anito-cel; the potential for anito-cel to become a best-in-class therapy for multiple myeloma; regulatory applications and related timelines, including the PDUFA date for anito-cel’s BLA; the potential of Arcellx’ cell therapy platform; filings and approvals relating to the transaction; the expected timing of the completion of the transaction; the ability satisfy the various closing conditions and complete the transaction; the expectation that the transaction will be accretive to Gilead following FDA approval of anito-cel in the future; and any assumptions underlying any of the foregoing. Investors are cautioned that any such forward-looking statements are not guarantees of future performance and involve risks and uncertainties and are cautioned not to place undue reliance on these forward-looking statements. Actual results may differ materially from those currently anticipated due to a number of risks and uncertainties. Risks and uncertainties that could cause the actual results to differ from expectations contemplated by forward-looking statements include: uncertainties as to the timing of the tender offer and merger; uncertainties as to how many of Arcellx’ stockholders will tender their stock in the offer; the possibility that competing offers will be made; the possibility that various closing conditions for the transaction may not be satisfied or waived, including that a governmental entity may prohibit, delay or refuse to grant approval for the consummation of the transaction; the effects of the transaction on relationships with employees, other business partners or governmental entities; the difficulty of predicting the timing or outcome of regulatory approvals or actions, if any; the risk that, if the transaction is consummated, the businesses will not be integrated successfully and that other anticipated benefits from the transaction will not be realized; any negative effects on the existing collaboration between Arcellx and Gilead that may result from the announcement of a transaction, or the failure to complete the transaction; the risk that the milestone associated with the CVR may not be achieved and that holders of CVRs may not receive payments in respect thereof; the impact of competitive products and pricing; other business effects, including the effects of industry, economic or political conditions outside of the companies’ control; transaction costs; actual or contingent liabilities; and other risks and uncertainties detailed from time to time in the companies’ periodic reports filed with the U.S. Securities and Exchange Commission (the “SEC”), including current reports on Form 8-K, quarterly reports on Form 10-Q and annual reports on Form 10-K, as well as the Schedule 14D-9 to be filed by Arcellx and the Schedule TO and related tender offer documents to be filed by Gilead and Arcellx Sub, Inc., a wholly owned subsidiary of Gilead. All forward-looking statements are based on information currently available to Gilead, and Gilead assume no obligation and disclaim any intent to update any such forward-looking statements.

Additional Information and Where to Find It

The tender offer described in this document has not yet commenced. This communication is for informational purposes only and is neither an offer to purchase nor a solicitation of an offer to sell securities of Arcellx, nor is it a substitute for any tender offer materials that Gilead, Ravens Sub, Inc. or Arcellx will file with the SEC. A solicitation and an offer to buy securities of Arcellx will be made only pursuant to an offer to purchase and related materials that Gilead intends to file with the SEC. At the time the tender offer is commenced, Gilead will file a Tender Offer Statement on Schedule TO with the SEC, and Arcellx will file a Solicitation/Recommendation Statement on Schedule 14D-9 with the SEC with respect to the tender offer. ARCELLX’ STOCKHOLDERS AND OTHER INVESTORS ARE URGED TO READ THE TENDER OFFER MATERIALS (INCLUDING AN OFFER TO PURCHASE, A RELATED LETTER OF TRANSMITTAL AND CERTAIN OTHER TENDER OFFER DOCUMENTS) AND THE SOLICITATION/RECOMMENDATION STATEMENT ON SCHEDULE 14D-9 BECAUSE THEY WILL CONTAIN IMPORTANT INFORMATION THAT SHOULD BE READ CAREFULLY BEFORE ANY DECISION IS MADE WITH RESPECT TO THE TENDER OFFER. The Offer to Purchase, the related letter of transmittal and certain other tender offer documents, as well as the Solicitation/Recommendation Statement on Schedule 14D-9, will be sent to all stockholders of Arcellx at no expense to them. The Tender Offer Statement on Schedule TO, the Solicitation/Recommendation Statement on Schedule 14D-9 and other related documents will be made available for free at the SEC’s web site at www.sec.gov. Additional copies may be obtained for free by contacting Gilead or Arcellx. Free copies of these materials and certain other offering documents will be made available by Gilead by mail to Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, attention: Investor Relations, by phone at 1-800-GILEAD-5 or 1-650-574-3000, or by directing requests for such materials to the information agent for the offer, which will be named in the Tender Offer Statement on Schedule TO. Investors and security holders of Arcellx may also obtain, free of charge, the Solicitation/Recommendation Statement on Schedule 14D-9 and other related documents that the Company has filed with or furnished to the SEC under the “Financials” section of Arcellx’ website at https://ir. Arcellx.com/financials/sec-filings/default.aspx.

In addition to the Offer to Purchase, the related Letter of Transmittal and certain other tender offer documents, as well as the Solicitation/Recommendation Statement, Gilead and Arcellx file annual, quarterly and current reports, proxy statements and other information with the SEC. Gilead’s and Arcellx’ filings with the SEC are also available for free to the public from commercial document-retrieval services and at the website maintained by the SEC at www.sec.gov.