Imbrium Therapeutics and Mundipharma EDO Announce Orphan Drug Designation for Relapsed Refractory Biliary Tract Cancer Treatment

Imbrium Therapeutics L.P., an operating subsidiary of Purdue Pharma L.P., in conjunction with Mundipharma EDO GmbH, announced on 2/21/19 that the U.S. Food and Drug Administration (FDA) has granted orphan drug designation (ODD) to its investigational drug etoposide toniribate, a novel topoisomerase II inhibitor, for the treatment of relapsed refractory biliary tract cancer.

Also known as cholangiocarcinoma, biliary tract cancer is a rare type of cancer that starts in the bile ducts, a series of thin tubes that move bile from the liver and gallbladder to the small intestine (duodenum) to help digest the fats in food. Biliary tract cancer is the second most common primary hepatobiliary cancer, after hepatocellular cancer. About 8,000 people in the United States are diagnosed with biliary tract cancer each year. It most commonly affects people age 65 or older.

“We are pleased that the FDA has granted orphan drug designation for etoposide toniribate as we believe, once approved, it can be an important clinical advance for patients suffering from relapsed refractory biliary tract cancer, a patient population that has limited treatment options,” said Paul Medeiros, president of Imbrium Therapeutics. “This designation represents Imbrium’s first milestone in oncology and underscores our commitment to advance the clinical development of oncology chemotherapeutics while actively collaborating to advance treatments across our therapeutic portfolio.”

Etoposide toniribate has shown encouraging data in Phase 2 trials, and these data were key in securing the ODD. The European Medicines Agency (EMA) granted orphan designation to etoposide toniribate on June 4, 2014.

Imbrium Therapeutics, in collaboration with Mundipharma EDO GmbH, expects to initiate a Phase 3 clinical trial of etoposide toniribate in patients with refractory biliary tract cancer in 2020.

Etoposide toniribate is a novel chemotherapy agent of the topoisomerase II inhibitor class in clinical development for the treatment of relapsed refractory biliary tract cancer. This small molecule drug is designed to work by metabolizing into its active form through enzymes in the gastrointestinal tract that are particularly active in cancer cells. Activated etoposide binds to and inhibits topoisomerase II, which is often elevated in tumors, resulting in double-strand breaks in tumor DNA. Damage to the tumor DNA induces apoptosis (programmed cell death).

Results of a randomized Phase 2 trial of 23 patients with refractory, metastatic, unresectable biliary tract cancer who had relapsed following treatment with gemcitabine/cisplatin showed a one-year overall survival of 44.4 percent with etoposide toniribate versus 11.3 percent with best supportive care (BSC). Overall, 55.6 percent of patients met the primary endpoint of disease control compared with 20.0 percent who received BSC. The most common drug-related adverse events were leukopenia, neutropenia, thrombocytopenia, anemia, alopecia, fatigue and abdominal pain.