FDA Speeds Possible Second-Line Treatment for Mesothelioma

The U.S. Food and Drug Administration awarded Fast Track designation recently to the WT1 cancer vaccine, moving it closer to becoming the first approved second-line treatment for malignant pleural mesothelioma.

The vaccine, also known as galinpepimut-S, is an immunotherapy agent that targets the WT1 protein, which is expressed in high levels in various cancers, such as mesothelioma, but it's rarely seen in normal adult cells. The protein is especially resistant to standard chemotherapy agents.

The National Cancer Institute in 2009 ranked WT1 as the top target of cancer immunotherapy research.

Sellas Life Sciences Group, a Switzerland-based biopharmaceutical company focused on immunotherapeutic agents, developed the vaccine.

“Galinpepimut-S has the potential to become a significant treatment modality to prolong survival for patients with mesothelioma,” Sellas CEO Dr. Angelos Stergiou told Asbestos.com. “We are exploring all developmental and regulatory options to make the vaccine available as soon as possible.”

Unmet Need for Second-Line Therapy for Mesothelioma

The FDA's Fast Track designation is designed to expedite the review of a drug and aid in its development. The FDA targets drugs that address unmet medical needs for serious and life-threatening diseases.

It usually takes federal regulators a decade or more to approve a drug.

Mesothelioma is a rare and aggressive cancer caused by exposure to asbestos fibers, typically after years of occupational exposure. Doctors diagnose the disease in an estimated 3,000 people annually in the U.S.

Earlier this year, the FDA granted the WT1 vaccine orphan drug designation after reviewing results of Sellas' phase II clinical trial involving 40 patients with pleural mesothelioma. The orphan drug designation also encourages drug development for rare diseases, but mostly by providing financial incentives.

Standard first-line treatment for mesothelioma is typically a combination of chemotherapy, surgery and radiation, but the majority of patients still live less than two years after diagnosis. Therapeutic progress has come slowly.

There currently is no FDA-approved second-line treatment (after first-line has stopped working), a void Sellas hopes its WT1 vaccine can fill.

WT1 Shows Impressive Early Results

Patients in Sellas' phase II, placebo-controlled clinical trial had a median overall survival of 24.8 months, compared to a median overall survival of 16.6 months for those not receiving the vaccine.

Sellas plans to conduct a mesothelioma phase III trial involving the WT1 vaccine in 2017. Sites for the multicenter trial have not been announced.

The research staff at Sellas expects better results in the next trial. The phase II trial included six vaccine injections administered to each patient once every two weeks. The phase III trial will include up to 12 vaccinations, along with booster injections.

“I wholeheartedly hope that we will be able to show equally exciting results in our next study,” Stergiou said. “Galinpepimut-S is demonstrating its potential as an anti-cancer agent with outstanding results.”

The WT1 vaccine also is in various developmental phases for use with ovarian cancer, multiple myeloma and a specific form of brain cancer.

Because most mesothelioma patients express the WT1 protein, they would benefit from the vaccine. Previous research shows its effectiveness is greatest as an enhancement to standard treatment, or when it's used to prevent recurrence of the disease.

“This cancer vaccine is truly exciting,” Stergious said. “The data has been encouraging.”

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