Partner Therapeutics Announces FDA Orphan Drug Designation for Sargramostim in Melanoma Treatment

On September 23, 2019, VCBeat (WeChat ID: vcbeat) learned from foreign media reports that biotechnology company Partner Therapeutics (PTx) announced that its hematologic drug sargramostim had been granted orphan drug designation by the U.S. Food and Drug Administration (FDA) for the treatment of melanoma.

Sargramostim is a single-chain glycosylated polypeptide composed of multiple amino acid residues. It was approved by the FDA for marketing in 1991, initially for the treatment of five hematologic oncology indications.

Melanoma is one of the most aggressive forms of skin cancer. Its pathological manifestations include the sudden appearance or rapid growth of pigmented nevi, progressive darkening of color, and the emergence of satellite nodules or pigmentary halos around the lesion. Patients are prone to experiencing local pain, infection, ulceration, bleeding, and lymphadenopathy. These tumors primarily occur on the lower extremities, followed by the head, neck, upper extremities, and eyes. According to estimates from the American Cancer Society (ACS), there were 96,480 new cases of melanoma in the United States in 2019, with approximately 7,230 patients presenting with advanced-stage disease that is difficult to cure.

The FDA established the Office of Orphan Products Development (OOPD) to encourage biotechnology and pharmaceutical companies to develop therapies for rare diseases. According to the WHO definition, rare diseases are those affecting 0.65% to 1% of the total population. If a drug receives FDA orphan drug designation, the sponsoring company will be granted seven years of market exclusivity upon the drug’s approval.

PTx, a comprehensive biopharmaceutical company founded in 2017 and headquartered in Boston, Massachusetts, USA, is dedicated to developing and commercializing innovative therapies to improve clinical outcomes for cancer patients. In February 2018, PTx completed a $60 million Series A financing round led by Perceptive Advisors and other investors.

The Eastern Cooperative Oncology Group (ECOG) previously reported the results of Study 1608, a Phase II clinical trial involving 245 patients. This study conducted clinical trials comparing the combination therapy versus monotherapy of sargramostim and ipilimumab (Yervoy), two drugs used in the treatment of advanced melanoma, to evaluate their therapeutic efficacy. The study demonstrated that concurrent use of ipilimumab and sargramostim extended patient survival.

In Study 1608, the most common grade 3–5 drug-related adverse events were diarrhea and rash, while concurrent administration of sargramostim and ipilimumab reduced the incidence of these adverse events. Furthermore, this regimen also mitigated drug-induced toxicities affecting the gastrointestinal tract and lungs.

Based on the results of Study 1608, ECOG will initiate a Phase II/III clinical trial (ECOG 6141) to evaluate the efficacy of concurrent administration of ipilimumab, sargramostim, and the PD-1 monoclonal antibody nivolumab (Opdivo) in patients with advanced or metastatic melanoma.

“Initially, sargramostim was used as an immunomodulator, but it was not a focal point in the medical field at that time,” said Bob Mulroy, CEO of PTx. “Leveraging the ability of granulocyte-macrophage colony-stimulating factor (GM-CSF) to counteract tumor immune resistance, PTx has continuously explored the efficacy of sargramostim in melanoma and other complex cancers. The orphan drug designation marks a significant milestone in the development of sargramostim. We are pleased that the FDA supports the treatment of rare diseases through programs such as orphan drug designation.”

(Compiled by Xu Xiaoxue)