Exelixis Announces Final Results from Phase 3 Pivotal CABINET Study Evaluating Cabozantinib in Advanced Neuroendocrine Tumors Presented at ESMO 2024 and Published in New England Journal of Medicine

ALAMEDA, Calif.--(BUSINESS WIRE)--Sep 16, 2024--

Exelixis, Inc. (Nasdaq: EXEL) today announced updated and final data from CABINET, a phase 3 pivotal trial evaluating cabozantinib (CABOMETYX ® ) versus placebo in two cohorts of patients with previously treated neuroendocrine tumors: one cohort with advanced pancreatic neuroendocrine tumors (pNET) and one cohort with advanced extra-pancreatic NET (epNET). These data are being presented today at the 2024 European Society for Medical Oncology Congress (ESMO 2024) during the Proffered Paper Session: NETs and Endocrine Tumours at 2:45 p.m. CET and were simultaneously published in the New England Journal of Medicine ( NEJM ).

“The phase 3 CABINET study, which was conducted through the National Cancer Institute's National Clinical Trials Network, reflects real-world clinical practice in that it enrolled a wide and heterogeneous range of patients regardless of primary tumor site, grade, somatostatin receptor expression and functional status,” said Jennifer Chan, M.D., M.P.H., study chair for the CABINET trial, Clinical Director of the Gastrointestinal Cancer Center and Director of the Program in Carcinoid and Neuroendocrine Tumors at Dana-Farber Cancer Institute. “I’m encouraged by these final results showing that cabozantinib provided a clinically meaningful treatment benefit for patients with previously treated advanced neuroendocrine tumors, including across all major clinical subgroups. The findings suggest that cabozantinib has the potential to become a new standard of care for these patients greatly in need of new treatment options.”

The final results from the CABINET study presented today at ESMO and published in NEJM demonstrate continued improvement with cabozantinib in the primary endpoint of progression-free survival (PFS) by blinded independent central review (BICR) through the data cutoff of August 24, 2023. In the pNET cohort (n=95), at a median follow-up of 13.8 months, the hazard ratio (HR) was 0.23 (95% confidence interval [CI]: 0.12-0.42; p<0.0001); median PFS was 13.8 months for cabozantinib versus 4.4 months for placebo. In the epNET cohort (n=203), at a median follow-up of 10.2 months, the HR was 0.38 (95% CI: 0.25-0.59; p<0.0001); median PFS was 8.4 months versus 3.9 months, respectively. Upon disease progression, patients were unblinded, and those receiving placebo were permitted to cross over to open-label therapy with cabozantinib.

Additional analyses suggest benefits with cabozantinib across all clinical subgroups examined, including primary tumor site, grade and prior systemic anticancer therapy. In the pNET cohort, the objective response rate (ORR) by BICR was 19% with cabozantinib compared with 0% with placebo. In the epNET cohort, the ORR by BICR was 5% with cabozantinib compared with 0% with placebo. Similar interim overall survival (OS) results for cabozantinib compared to placebo were observed in both cohorts; HRs for OS were 0.95 (95% CI: 0.45-2.00) for the pNET cohort and 0.86 (95% CI: 0.56-1.31) for the epNET cohort.

“Patients with advanced neuroendocrine tumors face a poor prognosis with limited treatment options. These updated data reinforce the potential of cabozantinib as a new treatment to significantly delay disease progression,” said Amy Peterson, M.D., Executive Vice President, Product Development & Medical Affairs, and Chief Medical Officer, Exelixis. “We believe the CABINET data indicate that cabozantinib could be practice-changing in NET, and we are working closely with the FDA to bring this differentiated option to patients with advanced NET as quickly as possible.”

The safety profile of cabozantinib observed in each cohort was consistent with its known safety profile; no new safety signals were identified. A majority of patients treated with cabozantinib required dose modifications or reductions to manage adverse events.

These results were the basis for Exelixis’ supplemental new drug application (sNDA) for cabozantinib for the treatment of adults with advanced NET. The FDA accepted the sNDA in August and assigned a Prescription Drug User Fee Act target action date of April 3, 2025.

In August of 2023, CABINET was stopped and unblinded early due to a dramatic improvement in PFS observed at an interim analysis in both of the trial’s cohorts, per a unanimous recommendation of the Alliance for Clinical Trials in Oncology independent Data and Safety Monitoring Board; all patients were unblinded, and those on placebo were given the option to cross over to active treatment with cabozantinib. Cabozantinib demonstrated a statistically significant and clinically meaningful improvement in PFS versus placebo based on results of both local review and available BICR. Initial results by investigator were presented at ESMO 2023.

About CABINET (Alliance A021602)
CABINET (Randomized, Double-Blinded Phase III Study of CAB ozantinib versus Placebo I n Patients with Advanced NE uroendocrine T umors After Progression on Prior Therapy) is sponsored by the National Cancer Institute (NCI), part of the National Institutes of Health, and is being led and conducted by the NCI-funded Alliance for Clinical Trials in Oncology with participation from the NCI-funded National Clinical Trials Network as part of Exelixis’ collaboration through a Cooperative Research and Development Agreement with the NCI’s Cancer Therapy Evaluation Program.

CABINET is a multicenter, randomized, double-blinded, placebo-controlled phase 3 pivotal trial that had enrolled a total of 298 patients in the U.S at the time of the final analysis. Patients were randomized 2:1 to cabozantinib (60 mg) or placebo in two separately powered cohorts (pNET, n=95; epNET, n=203). The epNET cohort included patients with the following primary tumor sites: gastrointestinal (GI) tract, lung, unknown primary sites and other. Each cohort was randomized separately and had its own statistical analysis plan. Patients must have had measurable disease per RECIST 1.1 criteria and must have experienced disease progression or intolerance after at least one U.S. FDA-approved line of prior therapy other than somatostatin analogs. The primary endpoint in each cohort was PFS per RECIST 1.1 by blinded independent central review. Secondary endpoints included overall survival, radiographic response rate and safety. More information about this trial is available at ClinicalTrials.gov.

About NET
NET are cancers that begin in the specialized cells of the body’s neuroendocrine system. 1 These cells have traits of both hormone-producing endocrine cells and nerve cells. 1 In the U.S., it is estimated that 161,000 to 192,000 people are living with unresectable, locally advanced or metastatic NET. 2 The number of people diagnosed with NET has been increasing in recent decades. 3 Functional NET release peptide hormones that can cause debilitating symptoms, like diarrhea, hypertension and flushing which may require focused treatment, while symptoms of non-functional NET are related primarily to tumor growth. 4,5 Most NET take years to develop and grow slowly, but eventually all patients with advanced or metastatic NET will develop refractory and progressing disease. 6,7

NET can develop in any part of the body, but most commonly start in the GI tract or in the lungs, where they have historically been referred to as carcinoid tumors and are more recently called epNET. 1 The five-year survival rates for advanced GI and lung NET tumors are 68% and 55%, respectively. 8,9 NET can also start in the pancreas, where they tend to be more aggressive, with a five-year survival rate of only 23% for advanced disease. 1,10 For advanced NET patients, treatment options include somatostatin analogs, chemotherapy, targeted therapy and peptide-receptor radionuclide therapy. 11

About CABOMETYX®(cabozantinib)
In the U.S., CABOMETYX tablets are approved as monotherapy for the treatment of patients with advanced renal cell carcinoma (RCC) and in combination with nivolumab for patients as a first-line treatment for patients with advanced RCC; for the treatment of patients with hepatocellular carcinoma (HCC) who have been previously treated with sorafenib, and; for adult and pediatric patients 12 years of age and older with locally advanced or metastatic differentiated thyroid cancer (DTC) that has progressed following prior VEGFR-targeted therapy and who are radioactive iodine-refractory or ineligible. CABOMETYX tablets have also received regulatory approvals in over 65 countries outside the U.S. and Japan, including the European Union. In 2016, Exelixis granted Ipsen Pharma SAS exclusive rights for the commercialization and further clinical development of cabozantinib outside of the U.S. and Japan. In 2017, Exelixis granted exclusive rights to Takeda Pharmaceutical Company Limited for the commercialization and further clinical development of cabozantinib for all future indications in Japan. Exelixis holds the exclusive rights to develop and commercialize cabozantinib in the U.S.

CABOMETYX is not indicated as a treatment for NET.

IMPORTANT SAFETY INFORMATION

WARNINGS AND PRECAUTIONS

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

Perforations and Fistulas: Fistulas, including fatal cases, occurred in 1% of CABOMETYX patients. Gastrointestinal (GI) perforations, including fatal cases, occurred in 1% of CABOMETYX patients. Monitor patients for signs and symptoms of fistulas and perforations, including abscess and sepsis. Discontinue CABOMETYX in patients who experience a Grade 4 fistula 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 events that require medical intervention.

Hypertension and Hypertensive Crisis: CABOMETYX can cause hypertension, including hypertensive crisis. Hypertension was reported in 37% (16% 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. Permanently discontinue CABOMETYX for severe hypertension that cannot be controlled with anti-hypertensive therapy or for hypertensive crisis.

Diarrhea: Diarrhea occurred in 62% of CABOMETYX patients. Grade 3 diarrhea occurred in 10% of CABOMETYX patients. Monitor and manage patients using antidiarrheals as indicated. Withhold CABOMETYX until improvement to ≤ Grade 1, resume at a reduced dose.

Palmar-Plantar Erythrodysesthesia (PPE): PPE occurred in 45% 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.

Hepatotoxicity: CABOMETYX in combination with nivolumab can cause hepatic toxicity with higher frequencies of Grades 3 and 4 ALT and AST elevations compared to CABOMETYX alone.

Monitor liver enzymes before initiation of and periodically throughout treatment. Consider more frequent monitoring of liver enzymes than when the drugs are administered as single agents. For elevated liver enzymes, interrupt CABOMETYX and nivolumab and consider administering corticosteroids.

With the combination of CABOMETYX and nivolumab, Grades 3 and 4 increased ALT or AST were seen in 11% of patients. ALT or AST >3 times ULN (Grade ≥2) was reported in 83 patients, of whom 23 (28%) received systemic corticosteroids; ALT or AST resolved to Grades 0-1 in 74 (89%). Among the 44 patients with Grade ≥2 increased ALT or AST who were rechallenged with either CABOMETYX (n=9) or nivolumab (n=11) as a single agent or with both (n=24), recurrence of Grade ≥2 increased ALT or AST was observed in 2 patients receiving CABOMETYX, 2 patients receiving nivolumab, and 7 patients receiving both CABOMETYX and nivolumab. Withhold and resume at a reduced dose based on severity.

Adrenal Insufficiency: CABOMETYX in combination with nivolumab can cause primary or secondary adrenal insufficiency. For Grade 2 or higher adrenal insufficiency, initiate symptomatic treatment, including hormone replacement as clinically indicated. Withhold CABOMETYX and/or nivolumab and resume CABOMETYX at a reduced dose depending on severity.

Adrenal insufficiency occurred in 4.7% (15/320) of patients with RCC who received CABOMETYX with nivolumab, including Grade 3 (2.2%), and Grade 2 (1.9%) adverse reactions. Adrenal insufficiency led to permanent discontinuation of CABOMETYX and nivolumab in 0.9% and withholding of CABOMETYX and nivolumab in 2.8% of patients with RCC.

Approximately 80% (12/15) of patients with adrenal insufficiency received hormone replacement therapy, including systemic corticosteroids. Adrenal insufficiency resolved in 27% (n=4) of the 15 patients. Of the 9 patients in whom CABOMETYX with nivolumab was withheld for adrenal insufficiency, 6 reinstated treatment after symptom improvement; of these, all (n=6) received hormone replacement therapy and 2 had recurrence of adrenal insufficiency.

Proteinuria: Proteinuria was observed in 8% of CABOMETYX patients. Monitor urine protein regularly during CABOMETYX treatment. For Grade 2 or 3 proteinuria, withhold CABOMETYX until improvement to ≤ Grade 1 proteinuria; resume CABOMETYX at a reduced dose. 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 3 weeks prior to scheduled dental surgery or invasive dental procedures, if possible. Withhold CABOMETYX for development of ONJ until complete resolution, resume at a reduced dose.

Impaired Wound Healing: Wound complications occurred with CABOMETYX. Withhold CABOMETYX for at least 3 weeks prior to elective surgery. Do not administer CABOMETYX for at least 2 weeks after major surgery and until adequate wound healing. The safety of resumption of CABOMETYX after resolution of wound healing complications has not been established.

Reversible Posterior Leukoencephalopathy Syndrome (RPLS): RPLS, a syndrome of subcortical vasogenic edema diagnosed by characteristic findings 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.

Thyroid Dysfunction: Thyroid dysfunction, primarily hypothyroidism, has been observed with CABOMETYX. Based on the safety population, thyroid dysfunction occurred in 19% of patients treated with CABOMETYX, including Grade 3 in 0.4% of patients.

Patients should be assessed for signs of thyroid dysfunction prior to the initiation of CABOMETYX and monitored for signs and symptoms of thyroid dysfunction during CABOMETYX treatment. Thyroid function testing and management of dysfunction should be performed as clinically indicated.

Hypocalcemia: CABOMETYX can cause hypocalcemia. Based on the safety population, hypocalcemia occurred in 13% of patients treated with CABOMETYX, including Grade 3 in 2% and Grade 4 in 1% of patients. Laboratory abnormality data were not collected in CABOSUN.

In COSMIC-311, hypocalcemia occurred in 36% of patients treated with CABOMETYX, including Grade 3 in 6% and Grade 4 in 3% of patients.

Monitor blood calcium levels and replace calcium as necessary during treatment. Withhold and resume at reduced dose upon recovery or permanently discontinue CABOMETYX depending on severity.

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 common (≥20%) adverse reactions are:

CABOMETYX as a single agent: diarrhea, fatigue, PPE, decreased appetite, hypertension, nausea, vomiting, weight decreased, and constipation.

CABOMETYX in combination with nivolumab: diarrhea, fatigue, hepatotoxicity, PPE, stomatitis, rash, hypertension, hypothyroidism, musculoskeletal pain, decreased appetite, nausea, dysgeusia, abdominal pain, cough, and upper respiratory tract infection.

DRUG INTERACTIONS

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.

USE IN SPECIFIC POPULATIONS

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. Avoid CABOMETYX in patients with severe hepatic impairment.

Please see accompanying full Prescribing Information
https://www.cabometyx.com/downloads/CABOMETYXUSPI.pdf.

You are encouraged to report negative side effects of prescription drugs to the FDA. Visithttp://www.fda.gov/medwatchor call 1-800-FDA-1088.

About Exelixis
Exelixis is a globally ambitious oncology company innovating next-generation medicines and regimens at the forefront of cancer care. Powered by drug discovery and development excellence, we are rapidly evolving our product portfolio to target an expanding range of tumor types and indications with our clinically differentiated pipeline of small molecules, antibody-drug conjugates and other biotherapeutics. This comprehensive approach harnesses decades of robust investment in our science and partnerships to advance our investigational programs and extend the impact of our flagship commercial product, CABOMETYX ® (cabozantinib). Exelixis is driven by a bold scientific pursuit to create transformational treatments that give more patients hope for the future. For information about the company and its mission to help cancer patients recover stronger and live longer, visit www.exelixis.com, follow @ExelixisInc on X (Twitter), like Exelixis, Inc. on Facebook and follow Exelixis on LinkedIn.

Exelixis Forward-Looking Statements
This press release contains forward-looking statements, including, without limitation, statements related to: the presentation of final results from the CABINET trial at ESMO 2024; the therapeutic potential of cabozantinib to become a new standard of care for patients with previously treated NET who are greatly in need of new treatment options, and Exelixis’ belief that cabozantinib could be practice-changing and significantly delay disease progression; Exelixis’ plans to work closely with the FDA to bring cabozantinib as a treatment option to patients with advanced NET as quickly as possible, as well as the FDA’s regulatory review process with respect to Exelixis’ sNDA submission, including the Prescription Drug User Fee Act target action date assigned by the FDA; and Exelixis’ scientific pursuit to create transformational treatments that give more patients hope for the future. 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: the availability of data at the referenced times; complexities and the unpredictability of the regulatory review and approval processes in the U.S. and elsewhere; Exelixis’ continuing compliance with applicable legal and regulatory requirements; unexpected concerns that may arise as a result of the occurrence of adverse safety events or additional data analyses of clinical trials evaluating cabozantinib; Exelixis’ dependence on its relationships with its cabozantinib commercial collaboration partners, including the level of their investment in the resources necessary to pursue regulatory approvals and successfully commercialize cabozantinib in the territories where approved; 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 detailed from time to time under the caption “Risk Factors” in Exelixis’ most recent Annual Report on Form 10-K and subsequent Quarterly Reports on Form 10-Q, and in Exelixis’ future filings with the Securities and Exchange Commission. 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, except as required by law.

Exelixis, the Exelixis logo and CABOMETYX are registered U.S. trademarks of Exelixis.

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1 Neuroendocrine Tumors. Cleveland Clinic website. Available at: https://my.clevelandclinic.org/health/diseases/22006-neuroendocrine-tumors-net. Accessed September 2024.
2 Population Estimate: Unresectable, Locally Advanced or Metastatic Extra-Pancreatic NET. June 2024 (internal data on file).
3 Pathak, S., Starr, J.S., Halfdanarson T., et al. Understanding the increasing incidence of neuroendocrine tumors. Expert Rev Endocrinol Metab. September 2023;18(5):377-385.
4 Pancreatic Neuroendocrine Tumors (Islet Cell Tumors) Treatment (PDQ ® )–Patient Version. NCI website. Available at: https://www.cancer.gov/types/pancreatic/patient/pnet-treatment-pdq. Accessed September 2024.
5 What Is a Pancreatic Neuroendocrine Tumor? ACS website. Available at: https://www.cancer.org/cancer/types/pancreatic-neuroendocrine-tumor/about/what-is-pnet.html. Accessed September 2024.
6 McClellan, K., Chen. E.Y, Kardosh A., et al. Therapy Resistant Gastroenteropancreatic Neuroendocrine Tumors. Cancers. 2022, 14(19), 4769.
7 What is a Gastrointestinal Carcinoid Tumor? ACS website. Available at: https://www.cancer.org/cancer/types/gastrointestinal-carcinoid-tumor/about/what-is-gastrointestinal-carcinoid.html. Accessed September 2024.
8 Survival Rates for Gastrointestinal Carcinoid Tumors. ACS website. Available at: https://www.cancer.org/cancer/types/gastrointestinal-carcinoid-tumor/detection-diagnosis-staging/survival-rates.html. Accessed September 2024.
9 Survival Rates for Lung Carcinoid Tumors. ACS website. Available at: https://www.cancer.org/cancer/types/lung-carcinoid-tumor/detection-diagnosis-staging/survival-rates.html. Accessed September 2024.
10 Survival Rates for Pancreatic Neuroendocrine Tumor. ACS website. Available at: https://www.cancer.org/cancer/types/pancreatic-neuroendocrine-tumor/detection-diagnosis-staging/survival-rates.html. Accessed September 2024.
11 Neuroendocrine Tumor (NET). NCI website. Available at: https://www.cancer.gov/pediatric-adult-rare-tumor/rare-tumors/rare-endocrine-tumor/carcinoid-tumor. Accessed September 2024.

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CONTACT: Investors Contact:

Susan Hubbard

EVP, Public Affairs and

Investor Relations

Exelixis, Inc.

(650) 837-8194

shubbard@exelixis.comMedia Contact:

Claire McConnaughey

Senior Director, Public Affairs

Exelixis, Inc.

(650) 837-7052

cmcconn@exelixis.com

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