Exhibit 99.6

Email to Immunomedics Employees

Hello Everyone, 

I’m very much looking forward to joining you virtually tomorrow for the townhall and wanted to share a few brief words in the meantime.

Let me start by saying how much respect I have for the incredible work you are doing at Immunomedics, and everything you have achieved to date. That respect is very much shared by the team at Gilead. We are delighted to have this opportunity to work with you in helping to bring the benefits of Trodelvy to patients around the world.

I know that the success you have achieved at Immunomedics is only possible when you have highly talented and committed individuals across the organization. We feel fortunate that we will now benefit from your talent and expertise, as we continue to build Gilead’s growing presence in oncology. I imagine you will have many questions about the future as you digest today’s news, and I want to assure you that we will do our best to provide answers as quickly as possible.

I have enjoyed getting to know Behzad in the lead up to today and I’m looking forward to learning more about the team and the work that you do. It is already clear to me that our two companies share common values and principles and a mission of helping patients to defeat their cancer. This mission has been a constant for me throughout my career and is important to all of us at Gilead.

I look forward to connecting tomorrow and to starting the conversation about what I believe will be an exciting future ahead.

Dan 

Forward-Looking Statements

This document contains forward-looking statements, within the meaning of the Private Securities Litigation Reform Act of 1995, related to Gilead, Immunomedics and the acquisition of Immunomedics 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 the companies’ and members of their senior management team. Forward-looking statements include, without limitation, statements regarding the business combination and related matters, prospective performance and opportunities, post-closing operations and the outlook for the companies’ businesses, including, without limitation, the ability of Gilead to advance Immunomedics’ product pipeline and successfully commercialize Trodelvy; expectations for achieving full U.S. Food and Drug Administration approval based on Immunomedics’ confirmatory data for Trodelvy and Immunomedics’ development of Trodelvy for additional indications; clinical trials (including the anticipated timing of clinical data, the funding therefor, anticipated patient enrollment, trial outcomes, timing or associated costs); the possibility of unfavorable results from clinical trials; regulatory applications and related timelines, including the filing and approval timelines for Biologics License Applications and supplements; filings and approvals relating to the transaction; the expected timing of the completion of the transaction; the ability to complete the transaction considering the various closing conditions; difficulties or unanticipated expenses in connection with integrating the companies; 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 Immunomedics’ 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; Immunomedics’ ability to meet post-approval compliance obligations (on topics including but not limited to product quality, product distribution and supply chain requirements, and promotional and marketing compliance); imposition of significant post-approval regulatory requirements on Immunomedics’ products, including a requirement for a post-approval confirmatory clinical study, or failure to maintain (if received) or obtain full regulatory approval for Immunomedics’ products due to a failure to satisfy post-approval regulatory requirements, such as the submission of sufficient data from a confirmatory clinical study; 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; adverse impacts on business, operating results or financial condition in the future due to pandemics, epidemics or outbreaks, such as COVID-19; 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 Immunomedics and the Schedule TO and related tender offer documents to be filed by Gilead and Purchaser. All forward-looking statements are based on information currently available to Gilead and Immunomedics, and Gilead and Immunomedics 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 document is for informational purposes only and is neither an offer to purchase nor a solicitation of an offer to sell shares of Immunomedics, nor is it a substitute for any tender offer materials that Gilead, Purchaser or Immunomedics will file with the SEC. A solicitation and an offer to buy shares of Immunomedics 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 Immunomedics will file a Solicitation/Recommendation Statement on Schedule 14D-9 with the SEC with respect to the tender offer. IMMUNOMEDICS’ 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 BECAUSE THEY WILL CONTAIN IMPORTANT INFORMATION WHICH 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, will be sent to all stockholders of Immunomedics at no expense to them. The Tender Offer Statement and the Solicitation/Recommendation Statement 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 Immunomedics. 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. Copies of the documents filed with the SEC by Immunomedics will be available free of charge under the “Investors” section of Immunomedics’ internet website at Immunomedics.com.

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 Immunomedics file annual, quarterly and current reports, proxy statements and other information with the SEC. Gilead’s and Immunomedics’ 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.