Bayer HealthCare announced that its investigational compound regorafenib (BAY 73-4506) has been granted Fast Track designation by the US Food and Drug Administration (FDA) for the treatment of patients with metastatic and/or unresectable Gastrointestinal Stromal Tumours (GIST) whose disease has progressed despite at least imatinib and sunitinib as prior treatments.

“There is a serious unmet medical need for this specific patient population,” said Kemal Malik, MD, Head of Global Development and member of the Bayer HealthCare Executive Committee. “This milestone is an important step in the overall development of regorafenib.”

In January, Bayer began enrolling patients in a randomized, double-blind, placebo-controlled phase III study of regorafenib plus best supportive care versus placebo plus best supportive care for subjects with metastatic and/or unresectable Gastrointestinal Stromal Tumours (GIST) 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), tumour 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.

Regorafenib is an investigational agent and is not approved by the FDA, the European Medicines Agency (EMA) or other Health Authorities.

Fast Track is a process designed to facilitate the development, and expedite the review of drugs to treat serious diseases and fill an unmet medical need. Fast Track addresses a broad range of serious diseases. Fast Track designation must be requested by the drug company and can be initiated at any time during the drug development process. Once a drug receives Fast Track designation, early and frequent communication between the FDA and a drug company is encouraged throughout the entire drug development and review process. The frequency of communication assures that questions and issues are resolved quickly, often leading to earlier drug approval and access by patients.

GIST is the most common form of sarcoma involving the gastrointestinal tract. It arises in the GI tract, with most primary tumours 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 US, 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-a receptor, which lead to uncontrolled signalling inside the tumour cells. Based on this knowledge therapeutic approaches to GIST focused on the inhibition of these mutated receptor molecules (referred 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-a, or in alternative signalling cascades such as RAF which leads to resistance to the approved drugs and tumour 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.

Regorafenib has shown anti-tumour activity in preclinical studies by inhibiting tumour growth in multiple xenograft models via anti-angiogenic and anti-proliferative mechanisms. Based on these results, regorafenib is currently being investigated in clinical trials for its potential to treat patients with various tumour types. Regorafenib is an investigational agent and is not approved by the FDA, the European Medical Association (EMA) or other Health Authorities.

The Bayer Group is a global enterprise with core competencies in the fields of health care, nutrition and high-tech materials. Its aim is to discover and manufacture products that will improve human and animal health worldwide.