– 54 percent objective response rate and 43 percent stable disease observed among 35 evaluable patients –

– Exelixis plans to initiate a pivotal phase 3 trial later this year –

– Results to be presented during an oral session on February 16 at the 2018 Multidisciplinary Head and Neck Cancers Symposium –

SOUTH SAN FRANCISCO, CA, USA I February 13, 2018 I Exelixis, Inc. (NASDAQ:EXEL) today announced results from a phase 2 investigator-sponsored trial (IST) of cabozantinib for the first-line treatment of metastatic radioiodine (RAI)-refractory differentiated thyroid carcinoma (DTC). The results were the subject of a news briefing that took place earlier today and will be presented during an oral session on February 16 starting at 1:30 p.m. MT at the 2018 Multidisciplinary Head and Neck Cancers Symposium, which is being held in Scottsdale, Arizona, February 15–17, 2018.

Patients with metastatic, RAI-refractory DTC were enrolled in this single-arm, open-label trial, and were administered oral cabozantinib 60 mg once daily. The primary endpoint of the trial is objective response rate. Among the 35 patients who were evaluable for response, partial response was achieved by 54 percent of patients (n=19), and stable disease was reported in 43 percent of patients (n=15) per RECIST 1.1. All but one evaluated patient experienced a decrease in tumor target lesions. Secondary endpoints of the trial include progression-free survival (PFS), time to progression (TTP), duration of response (DOR) and clinical benefit rate (CBR) defined as the number of patients achieving an objective response or stable disease for at least 6 months. The CBR at six months was 80 percent (n=28). With a median follow up for the study of 35 weeks the median PFS has not been reached. The median TTP among those patients who progressed was 35 weeks.

“While many patients with differentiated thyroid cancer can be treated successfully with radioiodine, there are very few options for those patients whose tumors have become resistant to treatment,” said Marcia Brose, M.D., Ph.D., Associate Professor of Otorhinolaryngology: Head and Neck Surgery and Director of the Center for Rare Cancers at the Abramson Cancer Center of the University of Pennsylvania, and principal investigator of the trial. “These findings suggest that cabozantinib, which showed encouraging efficacy and a manageable safety profile in this phase 2 trial, may be a promising treatment option for this patient population and warrants further evaluation.”

“We are dedicated to supporting investigator-sponsored trials focused on evaluating cabozantinib in a range of tumor types to help inform our ongoing development program whose main goal is to provide improved treatment options to patients in need,” said Gisela Schwab, M.D., President, Product Development and Medical Affairs and Chief Medical Officer, Exelixis. “Based on these promising results and data from other studies of cabozantinib in previously treated DTC, Exelixis plans to initiate a pivotal phase 3 study with cabozantinib in patients with advanced DTC later this year.”

The most common treatment-related adverse events included hyperglycemia (80 percent), diarrhea (77 percent), malaise/fatigue (74 percent), and weight loss (71 percent). The majority of these adverse events were grade 1 or 2. The most comment grade 3-5 adverse events occurring in more than one patient included hypertension (14 percent), increased lipase (9 percent), pulmonary embolism (6 percent), and hyponatremia (6 percent).

About the Trial

The IST is being conducted by the Center for Rare Cancers and Personalized Therapy at the Abramson Cancer Center of the University of Pennsylvania. Enrollment for the trial was completed in August 2017. Dr. Marcia Brose, Associate Professor of Otorhinolaryngology: Head and Neck Surgery, Perelman School of Medicine of the University of Pennsylvania is the principal investigator. The median age of patients is 65 years (range 45 to 84) and 17 patients (49 percent) are male. Of the patients in the trial, 23 (66 percent) had papillary thyroid cancer, 3 (9 percent) had follicular (Hürthle cell) thyroid cancer and 9 (26 percent) had poorly differentiated histology. Patients are administered oral cabozantinib 60 mg once daily as long as they continue to derive clinical benefit or until unacceptable drug-related toxicity. Sixteen patients remain on the trial as of February 6, 2018.

About Differentiated Thyroid Carcinoma

Thyroid cancer is commonly diagnosed at a younger age than most other adult cancers and is the most rapidly increasing cancer in the U.S., tripling in incidence in the past three decades.1 Approximately 54,000 new cases of thyroid cancer will be diagnosed in the U.S. in 2018.1 Nearly three out of four of these cases will be in women.1 Cancerous thyroid tumors include differentiated, medullary and anaplastic forms.1

Differentiated thyroid tumors, which make up about 90 percent of all thyroid cancers, are typically treated with surgery followed by ablation of the remaining thyroid with radioiodine.2 Approximately 5 to 15 percent of differentiated thyroid tumors are resistant to radioiodine treatment.3 For these patients, life expectancy is only three to six years from the time metastatic lesions are detected.4-6

About CABOMETYX® (cabozantinib)

CABOMETYX tablets are approved in the United States for the treatment of patients with advanced RCC. CABOMETYX tablets are also approved in the European Union, Norway, Iceland, Australia and Switzerland for the treatment of advanced RCC in adults who have received prior vascular endothelial growth factor (VEGF)-targeted therapy. Ipsen also submitted to European Medicines Agency (EMA) the regulatory dossier for cabozantinib as a treatment for first-line advanced RCC in the European Union on August 28, 2017; on September 8, 2017, Ipsen announced that the EMA validated the application. In 2016, Exelixis granted Ipsen exclusive rights for the commercialization and further clinical development of cabozantinib outside of the United States 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, including RCC.

CABOMETYX is not indicated for the treatment of differentiated thyroid carcinoma.

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 genetic systems, 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. We discovered our lead compounds, cabozantinib and cobimetinib, and advanced them into clinical development before entering into partnerships with leading biopharmaceutical companies in our efforts to bring these medicines to patients globally. We are steadfast in our commitment to prudently reinvest in our business to maximize the potential of our pipeline. We intend to supplement 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 recently earned a spot on Deloitte’s Technology Fast 500 list, a yearly award program honoring the 500 fastest-growing companies over the past four years. For more information about Exelixis, please visit www.exelixis.com or follow @ExelixisInc on Twitter.


  1. American Cancer Society. Key Statistics for Thyroid Cancer. https://www.cancer.org/cancer/thyroid-cancer/about/key-statistics.html. Accessed January 2018.
  2. Cooper DS, et al. 2009. Revised American Thyroid Association management guidelines for patients with thyroid nodules and differentiated thyroid cancer: the American Thyroid Association (ATA) Guidelines Taskforce on Thyroid Nodules and Differentiated Thyroid Cancer. Thyroid 19:1167–1214.
  3. Worden F. 2014. Treatment strategies for radioactive iodine-refractory differentiated thyroid cancer. Ther Adv Med Oncol 6:267–279.
  4. Xing M, Haugen BR, Schlumberger M. 2013. Progress in molecular-based management of differentiated thyroid cancer. Lancet 381:1058–1069.
  5. Pacini F, et al. 2012. Radioactive iodine-refractory differentiated thyroid cancer: unmet needs and future directions. Expert Rev Endocrinol Metab 7:541–554.
  6. Durante C, et al. 2006. Long-term outcome of 444 patients with distant metastases from papillary and follicular thyroid carcinoma: benefits and limits of radioiodine therapy. J Clin Endocrinol Metab 91:2892–2899.

SOURCE: Exelixis