DURHAM, N.C.—Chimerix and Cantex Pharmaceuticals Inc. have established an exclusive worldwide license centered on the latter’s CX-01, which is being developed as a first-line treatment for acute myeloid leukemia (AML). Per the terms of the agreement, Chimerix gains exclusive worldwide rights to develop and commercialize CX-01. In return, the company will pay Cantex $30 million up front, and will also issue 10 million shares of its common stock to Cantex. Cantex also stands to receive regulatory and commercial milestones of up to $587.5 million and tiered royalties starting at 10 percent.
Dr. Stephen Marcus, CEO of Cantex, stated, “We are very pleased to be partnering with Chimerix and their world-class scientists. We believe that Chimerix management’s track record in developing novel cancer therapeutics makes Chimerix the perfect partner to aggressively advance the development of CX-01 for the treatment of AML and other hematologic malignancies.”
CX-01 is derived from unfractionated heparin with very low anticoagulant activity. The compound targets protein pathways that are key for AML blast cell migration to the bone marrow and the retention of such cells in the marrow. It also binds with proteins that play a role in chemotherapy resistance and platelets’ delayed recovery after chemo. As a result, AML blasts are sensitized to chemotherapy, providing better clinical responses.
In a Phase 2 study, patients who had been recently diagnosed with AML were randomized to receive either 0.125 mg/kg/hr of CX-01 plus standard 7+3 chemotherapy (seven days of cytarabine, three of antracycline), 0.250 mg/kg/hr plus standard 7+3 chemotherapy, or 7+3 chemotherapy alone (control arm). The 0.25 mg/kg/hr seemed to have the best results compared to control, with a complete response rate (complete response or complete response without complete hematologic recovery) of 89 percent vs. 58 percent. That arm also saw median event-free survival of 23.4 months vs. nine months compared to control, and median overall survival that had not yet been reached for the CX-01 arm vs. 11.2 months for control. A single-arm pilot study of CX-01 as a first-line therapy also saw a complete response rate of 92 percent.
CX-01 was well tolerated in all treatment arms, with similar adverse events; the most common of these was febrile neutropenia, with three cases in each treatment arm and one in the control arm.
These data were presented at this year’s ASCO meeting, and were key to Chimerix’s interest in CX-01.
“For AML patients, five-year survival rates are below 30 percent, and many of these patients may never achieve an initial remission following front-line therapy. Clearly, we need better options for these patients,” Chimerix President and CEO Mike Sherman said in a conference call regarding the deal. “Most of the recent developments in this space have been targeted niche patient populations or in the relapsed/refractory setting. What’s missing is a new treatment with the potential to transform the effectiveness of the standard front-line 7+3 chemo regimen in a broad population of AML patients. Clinical data supports this potential for CX-01. With 21,000 patients diagnosed with AML annually in the U.S. alone, this translates to an opportunity to provide benefit for a large number of patients.
“As you look at the AML landscape, CX-01 is a product that could be complementary to other advances in care. Given its attractive safety profile, it’s well positioned to combine with any number of other therapies, including new and emerging targeted agents. The multiple protein targets of CX-01 also position it as a platform technology with applicability to other hematologic cancers.”
One such additional indication is myelodysplastic syndromes, conditions in which the bone marrow cells responsible for creating blood cells do not produce healthy adult cells. Cantex Pharmaceuticals has been advancing CX-01 in this indication as well, and the compound recently completed a Phase 2 trial in myelodysplastic syndromes.
Chimerix plans to advance CX-01 into Phase 3 development rapidly, with the goal of initiating a registrational trial in AML by the middle of next year.
“While several new agents have been recently approved for AML, a backbone of cytotoxic chemotherapy continues to be necessary for treatment with curative intent. If our results are confirmed, combining CX-01 with chemotherapy has the potential to have a significant impact on the outcomes of patients suffering from one of the most challenging hematologic malignancies,” commented Dr. Paul Shami, a clinical investigator at Huntsman Cancer Institute and Professor of Medicine at the University of Utah.
