[caption id="attachment_9277" align="alignleft" width="1079"] Press Release[/caption]

New pivotal trials will evaluate the combination of cabozantinib and atezolizumab in patients with advanced non-small cell lung cancer, castration-resistant prostate cancer and?renal cell carcinoma??

??Collaboration based on data from phase 1b COSMIC-021 trial??

ALAMEDA, Calif.--(BUSINESS WIRE)--Dec. 19, 2019--?Exelixis, Inc.?(NASDAQ:EXEL) today announced a collaboration agreement with?Roche?to evaluate cabozantinib (CABOMETYX^?), Exelixis? small molecule inhibitor of receptor tyrosine kinases, in combination with atezolizumab (TECENTRIQ^?), Roche?s PD-L1 immune checkpoint inhibitor, in patients with locally advanced or metastatic solid tumors. The clinical program, which will be co-funded by the companies, is expected to include three phase 3 pivotal trials in advanced non-small cell lung cancer (NSCLC), castration-resistant prostate cancer (CRPC) and renal cell carcinoma (RCC). ?Encouraging phase 1 data suggests this combination of cabozantinib and atezolizumab may improve outcomes for patients with prostate, lung and kidney cancers, and we look forward to collaborating with?Roche?to learn more in these pivotal trials,? said?Michael M. Morrissey, Ph.D., President and Chief Executive Officer of?Exelixis. ?This clinical collaboration is an important further step in our committed efforts to maximize the value of the cabozantinib franchise through these cost-sharing clinical collaborations in additional high-impact indications, while building value with new compounds from internal and external sources in 2020 and beyond.? The clinical development collaboration builds on encouraging activity observed in the phase 1b COSMIC-021 trial. The trial is currently enrolling 24 expansion cohorts in 12 tumor types including RCC, NSCLC and CRPC. TECENTRIQ^??(atezolizumab) is a registered trademark of Genentech, a member of the?Roche Group. About CABOMETYX^??(cabozantinib) In the U.S., CABOMETYX tablets are approved for the treatment of patients with advanced RCC and for the treatment of patients with hepatocellular carcinoma who have been previously treated with sorafenib. CABOMETYX tablets have also received regulatory approvals in the?European Union?and additional countries and regions worldwide. About Exelixis? Collaboration with?Ipsen On?February 29, 2016,?Exelixis?and?Ipsen?jointly announced an exclusive licensing agreement for the commercialization and further development of cabozantinib indications outside of?the United States,?Canada?and?Japan. On?December 21, 2016, this agreement was amended to include commercialization rights for?Ipsen?in?Canada. Under the parties? collaboration agreement, if?Ipsen?opts to participate in funding these phase 3 trials, or future studies,?Ipsen?will have access to the respective study results to support potential future regulatory submissions in their territory. About Exelixis? Collaboration with Takeda On?January 30, 2017,?Exelixis?and Takeda jointly announced an exclusive licensing agreement for the commercialization and further development of cabozantinib indications in?Japan. Under the parties? collaboration agreement, if Takeda opts to participate in funding these phase 3 trials, or future studies, Takeda will have access to the respective study results to support potential future regulatory submissions in their territory. Exelixis?holds the exclusive rights to develop and commercialize cabozantinib in?the United States. U.S. Important Safety Information

• Hemorrhage:?Severe and fatal hemorrhages occurred with CABOMETYX. The incidence of Grade 3 to 5 hemorrhagic events was 5% in CABOMETYX patients. Discontinue CABOMETYX for Grade 3 or 4 hemorrhage. Do not administer CABOMETYX to patients who have a recent history of hemorrhage, including hemoptysis, hematemesis, or melena.

• Perforations and Fistulas:?GastrointestinaI (GI) perforations, including fatal cases, occurred in 1% of CABOMETYX patients. Fistulas, including fatal cases, occurred in 1% of CABOMETYX patients. Monitor patients for signs and symptoms of perforations and fistulas, including abscess and sepsis. Discontinue CABOMETYX in patients who experience a fistula that cannot be appropriately managed or a GI perforation.

• Thrombotic Events:?CABOMETYX increased the risk of thrombotic events. Venous thromboembolism occurred in 7% (including 4% pulmonary embolism) and arterial thromboembolism in 2% of CABOMETYX patients. Fatal thrombotic events occurred in CABOMETYX patients. Discontinue CABOMETYX in patients who develop an acute myocardial infarction or serious arterial or venous thromboembolic event requiring medical intervention.

• Hypertension and Hypertensive Crisis:?CABOMETYX can cause hypertension, including hypertensive crisis. Hypertension occurred in 36% (17% Grade 3 and <1% Grade 4) of CABOMETYX patients. Do not initiate CABOMETYX in patients with uncontrolled hypertension. Monitor blood pressure regularly during CABOMETYX treatment. Withhold CABOMETYX for hypertension that is not adequately controlled with medical management; when controlled, resume at a reduced dose. Discontinue CABOMETYX for severe hypertension that cannot be controlled with anti-hypertensive therapy or for hypertensive crisis.

• Diarrhea:?Diarrhea occurred in 63% of CABOMETYX patients. Grade 3 diarrhea occurred in 11% of CABOMETYX patients. Withhold CABOMETYX until improvement to Grade 1 and resume at a reduced dose for intolerable Grade 2 diarrhea, Grade 3 diarrhea that cannot be managed with standard antidiarrheal treatments, or Grade 4 diarrhea.

• Palmar-Plantar Erythrodysesthesia (PPE):?PPE occurred in 44% of CABOMETYX patients. Grade 3 PPE occurred in 13% of CABOMETYX patients. Withhold CABOMETYX until improvement to Grade 1 and resume at a reduced dose for intolerable Grade 2 PPE or Grade 3 PPE.

• Proteinuria:?Proteinuria occurred in 7% of CABOMETYX patients. Monitor urine protein regularly during CABOMETYX treatment. Discontinue CABOMETYX in patients who develop nephrotic syndrome.

• Osteonecrosis of the Jaw (ONJ):?ONJ occurred in <1% of CABOMETYX patients. ONJ can manifest as jaw pain, osteomyelitis, osteitis, bone erosion, tooth or periodontal infection, toothache, gingival ulceration or erosion, persistent jaw pain, or slow healing of the mouth or jaw after dental surgery. Perform an oral examination prior to CABOMETYX initiation and periodically during treatment. Advise patients regarding good oral hygiene practices. Withhold CABOMETYX for at least 28 days prior to scheduled dental surgery or invasive dental procedures. Withhold CABOMETYX for development of ONJ until complete resolution.

• Wound Complications:?Wound complications were reported with CABOMETYX. Stop CABOMETYX at least 28 days prior to scheduled surgery. Resume CABOMETYX after surgery based on clinical judgment of adequate wound healing. Withhold CABOMETYX in patients with dehiscence or wound healing complications requiring medical intervention.

• Reversible Posterior Leukoencephalopathy Syndrome (RPLS):?RPLS, a syndrome of subcortical vasogenic edema diagnosed by characteristic finding on MRI, can occur with CABOMETYX. Evaluate for RPLS in patients presenting with seizures, headache, visual disturbances, confusion, or altered mental function. Discontinue CABOMETYX in patients who develop RPLS.

• Embryo-Fetal Toxicity:?CABOMETYX can cause fetal harm. Advise pregnant women and females of reproductive potential of the potential risk to a fetus. Verify the pregnancy status of females of reproductive potential prior to initiating CABOMETYX and advise them to use effective contraception during treatment and for 4 months after the last dose.

• Adverse Reactions:?The most commonly reported (=25%) adverse reactions are: diarrhea, fatigue, decreased appetite, PPE, nausea, hypertension, and vomiting.

• Strong CYP3A4 Inhibitors:?If coadministration with strong CYP3A4 inhibitors cannot be avoided, reduce the CABOMETYX dosage. Avoid grapefruit or grapefruit juice.

• Strong CYP3A4 Inducers:?If coadministration with strong CYP3A4 inducers cannot be avoided, increase the CABOMETYX dosage.?Avoid St.?John?s wort.

• Lactation:?Advise women not to breastfeed during CABOMETYX treatment and for 4 months after the final dose.

• Hepatic Impairment:?In patients with moderate hepatic impairment, reduce the CABOMETYX dosage. CABOMETYX is not recommended for use in patients with severe hepatic impairment.

Please see accompanying full Prescribing Information?https://cabometyx.com/downloads/CABOMETYXUSPI.pdf. About?Exelixis Founded in 1994,?Exelixis, Inc.?(NASDAQ:EXEL) is a commercially successful, oncology-focused biotechnology company that strives to accelerate the discovery, development and commercialization of new medicines for difficult-to-treat cancers. Following early work in model system genetics, we established a broad drug discovery and development platform that has served as the foundation for our continued efforts to bring new cancer therapies to patients in need. Our discovery efforts have resulted in four commercially available products, CABOMETYX^??(cabozantinib), COMETRIQ^??(cabozantinib), COTELLIC^??(cobimetinib) and MINNEBRO^??(esaxerenone), and we have entered into partnerships with leading pharmaceutical companies to bring these important medicines to patients worldwide. Supported by revenues from our marketed products and collaborations, we are committed to prudently reinvesting in our business to maximize the potential of our pipeline. We are supplementing our existing therapeutic assets with targeted business development activities and internal drug discovery ? all to deliver the next generation of?Exelixis?medicines and help patients recover stronger and live longer.?Exelixis?is a member of the Standard & Poor?s (S&P) MidCap 400 index, which measures the performance of profitable mid-sized companies. For more information about?Exelixis, please visit?www.exelixis.com, follow @ExelixisInc?on Twitter or like?Exelixis, Inc.?on?Facebook. Exelixis Forward-Looking Statements This press release contains forward-looking statements, including, without limitation, statements related to: Exelixis? expectation that the clinical program co-funded by?Exelixis?and?Roche?will include three phase 3 pivotal trials evaluating the combination of cabozantinib and atezolizumab in NSCLC, CRPC and RCC; the potential for the combination of cabozantinib and atezolizumab to improve outcomes for patients with prostate, lung and kidney cancers; Exelixis? belief that it can maximize the value of the cabozantinib franchise through these cost-sharing clinical collaborations in additional high-impact indications, while building value with new compounds from internal and external sources in 2020 and beyond; and Exelixis? plans to reinvest in its business to maximize the potential of the company?s pipeline, including through targeted business development activities and internal drug discovery. Any statements that refer to expectations, projections or other characterizations of future events or circumstances are forward-looking statements and are based upon Exelixis? current plans, assumptions, beliefs, expectations, estimates and projections. Forward-looking statements involve risks and uncertainties. Actual results and the timing of events could differ materially from those anticipated in the forward-looking statements as a result of these risks and uncertainties, which include, without limitation: risks and uncertainties related to regulatory review and approval processes and Exelixis? compliance with applicable legal and regulatory requirements; the potential failure of the combination of cabozantinib and atezolizumab to demonstrate safety and/or efficacy in COSMIC-021 or in future phase 3 pivotal trials; uncertainties inherent in the product development process; the costs of conducting clinical trials, including the ability or willingness of Exelixis? collaboration partners to invest in the resources necessary to complete the trials; Exelixis? dependence on third-party vendors for the development, manufacture and supply of cabozantinib; Exelixis? ability to protect its intellectual property rights; market competition, including the potential for competitors to obtain approval for generic versions of CABOMETYX; changes in economic and business conditions; and other factors affecting?Exelixis?and its development programs discussed under the caption ?Risk Factors? in Exelixis? Quarterly Report on Form 10-Q filed with the?Securities and Exchange Commission?(SEC) on?October 30, 2019, and in Exelixis? future filings with the?SEC. All forward-looking statements in this press release are based on information available to?Exelixis?as of the date of this press release, and?Exelixis?undertakes no obligation to update or revise any forward-looking statements contained herein.

Exelixis, the?Exelixis?logo, CABOMETYX, COMETRIQ and COTELLIC are registered U.S. trademarks. MINNEBRO is a Japanese trademark.

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Source:?Exelixis, Inc. Investors: Susan Hubbard EVP, Public Affairs and Investor Relations Exelixis, Inc. (650) 837-8194 shubbard@exelixis.com Media: Lindsay Treadway Senior Director, Public Affairs and Advocacy Relations Exelixis, Inc. (650) 837-7522