"Despite treatment advances over the past several years, GIST remains a potentially fatal disease, and there is still a significant unmet medical need for additional treatment options for the majority of patients," said Kemal Malik, MD, Head of Global Development and member of the Bayer HealthCare Executive Committee. "This is an important step in the overall development process for this investigational compound."
In January, Bayer announced that the company started to enroll patients in an international, randomized, double-blind, placebo-controlled, multi-center, cross-over Phase III trial to evaluate regorafenib for the treatment of patients with metastatic and/or unresectable gastrointestinal stromal tumors whose disease has progressed despite prior treatment with at least imatinib and sunitinib. The trial is estimated to enroll 170 patients, who will be randomized in a 2:1 ratio to receive either regorafenib or placebo. Subjects receiving placebo who experience disease progression may be offered open label regorafenib treatment (cross over option).
The primary endpoint of this trial is progression-free survival (PFS), and secondary endpoints include overall survival (OS), time to progression (TTP), disease control rate (DCR), tumor response rate (RR), duration of response (DOR), and safety. All patients will enter the Survival Follow-Up Period upon discontinuation of study treatment, during which assessment of survival status will be performed every three months.
Orphan Drug Designation in the United States
In the United States, the Orphan Drugs Act (ODA) provides for the orphan drug designation which aims to encourage the development of drugs involved in the diagnosis, prevention or treatment of a medical condition affecting fewer than 200,000 people in the country. The designation grants U.S. market exclusivity to a drug for a particular indication for a seven-year period if the sponsor complies with certain FDA specifications. Additional incentives for the sponsor include tax credits related to clinical trial expenses and a possible exemption from the FDA-user fee. The designation does not shorten the duration of the regulatory review and approval process.
GIST is the most common form of sarcoma involving the gastrointestinal tract. GISTs arise in the GI tract, with most primary tumors originating in the stomach or small intestine. GIST represents a potentially life-threatening malignancy if the disease has spread to other parts of the body (metastasized) or is unable to be surgically removed with curative intent. The incidence of GIST is estimated to be 11 to 20 patients per million per year. In the U.S., it is estimated that there are approximately 4,500-6,000 new cases of GISTs diagnosed each year, of which about 1,500 have already metastasized when they are initially found. GISTs are difficult to diagnose and are usually found incidentally when the doctor is looking for other problems.
GIST has become a paradigm of personalized cancer medicine in the past decade when it was discovered that most GISTs are caused by activating mutations in the KIT or PDGFR-α receptor, which lead to uncontrolled signaling inside the tumor cells. Based on this knowledge therapeutic approaches to GIST focused on the inhibition of these mutated receptor molecules (refered to as molecular targeted therapy). Imatinib and sunitinib, which inhibit oncogenic KIT, are currently the only two drugs approved for first and second-line treatment of metastatic and/or unresectable GISTs, respectively. Eventually these therapies fail due to the clonal emergence of secondary mutations in KIT or PDGFR-α, or in alternative signaling cascades such as RAF which leads to resistance to the approved drugs and tumor progression.
Regorafenib is an investigational oral multi-kinase inhibitor of angiogenic, stromal and oncogenic (receptor tyrosine) kinases (TK). Regorafenib inhibits angiogenic kinases like receptors for VEGF and the TIE2 receptor which play central roles in angiogenesis. It also inhibits various oncogenic kinases including RAF, RET and KIT, thereby helping to stop the proliferation of cancer cells.(i) Regorafenib has shown antitumor activity in preclinical studies by inhibiting tumor growth in multiple xenograft models via antiangiogenic and antiproliferative mechanisms. Based on these results, regorafenib is currently being investigated in clinical trials for its potential to treat patients with various tumor types.
Regorafenib is an investigational agent and is not approved by the FDA, the European Medical Association (EMA) or other Health Authorities.
About Bayer HealthCare
The Bayer Group is a global enterprise with core competencies in the fields of health care, nutrition and high-tech materials. Bayer HealthCare, a subgroup of Bayer AG with annual sales of EUR 15,988 million (2009), is one of the world's leading, innovative companies in the healthcare and medical products industry and is based in Leverkusen, Germany. The company combines the global activities of the Animal Health, Consumer Care, Medical Care and Pharmaceuticals divisions. Bayer HealthCare's aim is to discover and manufacture products that will improve human and animal health worldwide. Bayer HealthCare has a global workforce of 53.400 employees and is represented in more than 100 countries.
(i) S. Wilhelm, et al. Regorafenib (Bay 73-4506): A New Oral Multikinase Inhibitor Of Angiogenic, Stromal, And Oncogenic Receptor Tyrosine Kinases With Potent Preclinical Antitumor Activity. Online International Journal of Cancer. December 17, 2010.