Exelixis reports promising interim data from ovarian cancer patients treated with XL184, including: a 32% confirmed response rate per RECIST in patients with platinum-resistant or platinum-sensitive disease, and a 64% overall week-12 disease control rate.
Exelixis, Inc. today reported interim data from the cohort of patients with advanced epithelial ovarian cancer, primary peritoneal, or fallopian tube carcinoma treated with XL184 in an ongoing phase 2 adaptive randomized discontinuation trial (RDT) . Ignace Vergote, M.D., Ph.D., Head of the Department of Obstetrics and Gynecology and Gynecologic Oncology at the Catholic University Hospital Leuven, Leuven, Belgium, will present the data in the Molecular-Targeted Therapies-Clinical Trials poster session (Abstract #407) on Thursday, November 18th, at the 22nd EORTC-NCI-AACR  Symposium on Molecular Targets and Cancer Therapeutics, being held in Berlin, Germany.
XL184 Activity in Patients with Ovarian Cancer
XL184 is an oral, potent inhibitor of MET, VEGFR2 and RET. MET overexpression has been observed in advanced ovarian cancer, and anti-VEGF pathway agents have shown clinical benefit in ovarian cancer patients. For these reasons, co-targeting of the MET and VEGF signaling pathways using XL184 may represent a promising treatment strategy.
As of the November 1, 2010 cut-off date, a total of 51 patients were enrolled into the ovarian cancer cohort, with 31 evaluable for response, and 41 evaluable for safety. The median number of prior systemic treatments was 2. Tumor shrinkage was observed in 30 of 37 (81%) patients with measurable metastatic lesions. Of 31 patients evaluable for response per RECIST (Response Evaluation Criteria In Solid Tumors), 10 (32%) achieved a confirmed partial response (PR). Stable disease (SD) was reported in 15 patients (48%) including 3 patients who achieved unconfirmed PRs. The overall week-12 disease control rate (DCR)(complete responses + partial responses + stable disease responses = DCR) was 64%.
Upon subset analysis, 5 of 17 platinum-refractory or -resistant patients (29%) evaluable for response per RECIST achieved a confirmed PR. SD was reported in 7 patients (41%) including 2 patients with unconfirmed PRs. The week-12 DCR was 59% in platinum-resistant/refractory patients. Durable responses have been observed, including 2 patients with platinum-refractory or resistant disease who remain on study for 34+ and 36+ weeks, and 3 patients with platinum-sensitive disease on study for 24, 24+, and 28+ weeks. Some patients have experienced reductions in the ovarian cancer blood marker CA125, but in general no clear concordance between CA125 changes and tumor shrinkage has been observed.
Safety data are available for 49 patients who had at least 6 weeks of follow-up. The most common grade greater-than or equal to 3 adverse events, regardless of causality were PPE (Palmar-Plantar Erythrodysesthesia) syndrome (also referred to as “hand-foot syndrome”) (12%), diarrhea (7%), fatigue, vomiting (each 5%), nausea, rash, abdominal pain, hypertension, and hypomagnesemia (each 2%).
“The activity of XL184 in women with both platinum-sensitive and platinum-resistant/refractory disease is unique and encouraging. The response rate and overall disease control rate of this oral agent are impressive especially in the group of patients with platinum refractory/resistant ovarian cancer, and compare favorably to other targeted and systemic agents in development,” said, Dr. Vergote. “I believe these encouraging data warrant further evaluation of XL184 in ovarian cancer.”
“The high response rate in patients with ovarian cancer is reflective of the broad anti-tumor activity of XL184 observed in multiple tumor types to date,” said Michael M. Morrissey, Ph.D., president and chief executive officer of Exelixis. “The data from the RDT underscore the novel and differentiated clinical activity of XL184 in diverse tumor indications with predominance of either soft tissue or bone involvement.”
To access the clinical data poster mentioned in this press release, please visit www.exelixis.com.
Broad Clinical Activity of XL184 – Randomized Discontinuation Trial
XL184 has demonstrated anti-tumor activity in 9 of 12 indications studied to date. In ongoing trials, compelling activity has been observed in medullary thyroid cancer, glioblastoma, and clear cell renal cancer. In the RDT, XL184 is being evaluated in nine different tumor types, with clear signals of activity in six: prostate, ovarian, hepatocellular, breast, non-small cell lung cancer and melanoma. The adaptive RDT design allowed for rapid simultaneous assessment of the activity of XL184 across nine different tumor indications. As of the November 1, 2010 cut-off date, a total of 397 patients have been enrolled into the nine disease-specific cohorts, with 273 evaluable for response, and 312 evaluable for safety. Of 273 patients evaluable for response per RECIST, 39 achieved a PR (either confirmed or unconfirmed) and 100 had SD at week 12. The week-12 DCR for the overall population was 49%, with the highest rates occurring in hepatocellular cancer (75%), castration-resistant prostate cancer (71%), ovarian cancer (64%), melanoma (45%), non-small cell lung cancer (42%) and breast cancer (42%). Of note, a breast cancer patient with evidence of bone metastasis on bone scan demonstrated evidence of resolution on bone scan accompanied by 29% reduction in tumor size. XL184 has been generally well tolerated with a consistent adverse event profile across the nine different RDT tumor types.
XL184, an inhibitor of tumor growth, metastasis and angiogenesis, simultaneously targets MET and VEGFR2, key kinases involved in the development and progression of many cancers, including ovarian cancer. It has recently been shown in preclinical models that treatment with selective inhibitors of VEGF signaling can result in tumors that are more invasive and aggressive compared to control treatment. In preclinical studies, upregulation of MET has been shown to occur in concert with development of invasiveness after selective anti-VEGF therapy, and may constitute a mechanism of acquired or evasive resistance to agents that target VEGF signaling. Accordingly, treatment with XL184 in similar preclinical studies resulted in tumors that were less invasive and aggressive compared to control or selective anti-VEGF treatment. Therefore, XL184 has the potential for improving outcomes in a range of indications, including those where selective anti-VEGF therapy has shown minimal or no activity.
Exelixis, Inc. is a development-stage biotechnology company dedicated to the discovery and development of novel small molecule therapeutics for the treatment of cancer. The company is leveraging its biological expertise and integrated research and development capabilities to generate a pipeline of development compounds with significant therapeutic and commercial potential for the treatment of cancer. Currently, Exelixis’ broad product pipeline includes investigational compounds in phase 3, phase 2, and phase 1 clinical development. Exelixis has established strategic corporate alliances with major pharmaceutical and biotechnology companies, including Bristol-Myers Squibb Company, sanofi-aventis, GlaxoSmithKline, Genentech (a wholly owned member of the Roche Group), Boehringer Ingelheim, and Daiichi-Sankyo. For more information, please visit the company’s web site at http://www.exelixis.com.
- Exelixis Reports Promising Interim Data From Patients With Ovarian Cancer Treated With XL184 – 32% confirmed response rate per RECIST in patients with platinum-resistant or platinum-sensitive disease, News Release, Exelixis, Inc., November 18, 2010.
- Vergote A. Sella, C. Bedell, L. et. al. Phase 2 study of XL184 in a cohort of ovarian cancer patients (pts) with measurable soft tissue disease. Abstract no. 407. 22nd EORTC-NCI-AACR Symposium on Molecular Targets and Cancer Therapeutics, Berlin, Germany, November 18, 2010. [after clicking on study title, search for "407" to view abstract].
- A Randomized Discontinuation Study of XL184 in Subjects With Advanced Solid Tumors, Clinical Trial Summary, ClinicalTrials.gov (NCT00940225).
- A list of open ovarian clinical trials involving the study of XL184.
- A list of open solid tumor clinical trials involving the study of XL184.
1/Rosner GL, Stadler W, Ratain MJ. et. al. Randomized discontinuation design: Application to cytostatic antineoplastic agents. J Clin Oncol 20:4478-4484, 2002. Pursuant to this design, all patients receive the investigational drug for an initial period of time. Patients with standard radiologic tumor shrinkage within that timeframe would continue investigational therapy, while those with radiologic progression or unacceptable toxicity would discontinue therapy. All patients with radiologic stable disease after the initial therapy period are then randomized to continuing or discontinuing therapy in a double-blind placebo-controlled manner. This is an enrichment strategy in which patients with the end point of interest are preferentially enrolled in the randomized portion and in which the heterogeneity of the randomized population is decreased. These two factors result in an increased power for detecting a clinically relevant difference and decrease the number of patients exposed to placebo. Importantly, the enrichment is driven by the properties of the investigational drug as opposed to clinical prognostic factors identified in historical untreated patients or patients treated with a different class of agents. In addition, the statistical behavior of the trial is not highly dependent on investigators’ assumptions regarding the “no dose effect” (i.e., non-receipt of drug = no effect) for time to progression or stable disease rate, and thus effectively deals with uncertainty in this variable. Finally, patients may find such a trial design more appealing, resulting in brisk accrual.