Galinpepimut-S (GPS) is an immunotherapy drug that is now being used to treat mesothelioma. New Phase 1 Clinical Trials are being conducted which use GPS in conjunction with the drug nivolumab (Opdivo®) to treat mesothelioma. The process helps the body’s own immune system recognize the cancer cells and kill them effectively.

What is Galinpepimut-S Plus Nivolumab?

Galinpepimut-S (GPS) is an immunotherapy drug that targets the Wilms Tumor 1 (WT1) protein, which is found in many malignancies and solid tumors such as mesothelioma. GPS is administered by the SELLAS Life Sciences Group.

Immunotherapy drugs are designed to help strengthen the patient’s immune system so the body builds up immunity to find and attack cancer cells.

GPS immune response can recognize and destroy cancer cells and provide ongoing support memory to the immune system, so the body can continue to destroy recurring tumors and cancer cells. This treatment has the potential to prolong survival by preventing relapse and recurrence in those in complete remission or with minimal residual disease.

Nivolumab (Opdivo®) is an FDA-approved immunotherapy drug for treating mesothelioma, melanoma, head and neck cancer, and other cancers.

This drug weakens the protective proteins that cancer cells use to disguise themselves from the body’s white blood cells. This makes it easier for white blood cells to successfully identify and attack cancer cells.

The promising early clinical trials indicate that patients with mesothelioma who are treated with GPS plus nivolumab may have extended life spans and increased quality of life.

Galinpepimut-S Plus Nivolumab Clinical Trial

In April 2019, SELLAS started a clinical trial with Memorial Sloan Kettering Cancer Center in New York.

The purpose of this trial was to see if the combination had the potential to show antitumor immune responses and clinical activity for patients with malignant pleural mesothelioma (MPM).

Participants in this trial were required to:

  • Be 18 years or older
  • Be able to care for themselves but unable to carry do normal activity or active work
  • Have measurable disease
  • Have a pathologic diagnosis of malignant pleural mesothelioma
  • Have positive immunohistochemical staining for WT1 within 60 days of treatment initiation
  • Have received at least 1 prior course of pemetrexed-based chemotherapy

Results From The Phase 1 Clinical Trial

The combination treatment of GPS plus nivolumab showed success in increasing patient survival.

The treatment resulted in median overall survival of 35.4 weeks in patients with macroscopic deposits of malignant pleural mesothelioma, who had received treatment for at least one month.

At a median follow-up of 35.4 weeks, the average overall survival was 35.3 weeks. The average progression-free survival (PFS) with the combination was 8.8 weeks. The median PFS was 7 weeks in this population.

“Considering the overall poor prognosis in this particular clinical setting, these preliminary data suggest that the combination of galinpepimut-S with the PD-1 inhibitor nivolumab may provide meaningful clinical benefit to patients with malignant pleural mesothelioma.”

- Angelos Stergiou, MD, ScDhc, president and CEO of SELLAS Life Sciences Group, Inc.

The only patient in the study with sarcomatoid mesothelioma was diagnosed with stage 4 cancer experienced a survival of 25 months, and is still alive as of June 2021.

What Do The Results Mean?

The GPS plus nivolumab trial results indicate that participants with mesothelioma had an overall median survival of a little over 35 weeks, which is an improvement over no treatment at all.

The Phase 1 trials are just the first step in the path towards FDA approval and access for the general public.

There is plenty of reason to be optimistic over these results since the trials have shown this treatment can improve quality of life and length of survival for mesothelioma patients.

Individuals with mesothelioma who are interested in participating in clinical trials should contact their mesothelioma specialist to learn more.

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Laura WrightWritten by:

Lead Editor

Laura Wright is a journalist and content strategist with more than 15 years of professional experience. She attended college at the University of Florida, graduating magna cum laude with a bachelor’s degree in journalism in 2008. Her writing has been featured in The Gainesville Sun and other regional publications throughout Florida.

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  1. “Galinpepimut-S (GPS) Therapy.” Galinpepimut-S (GPS) Therapy, Sellas Life Sciences,

  2. Rosa, Kristi. “Galinpepimut-S Plus Nivolumab Shows Promising Preliminary Benefit in Mesothelioma.” OncLive, OncLive, 28 June 2021,

  3. SELLAS Life Sciences Group and World-Renowned Cancer Center to Study Galinpepimut-S (GPS) in Combination with Nivolumab in Patients with Malignant Pleural Mesothelioma (MPM),
    Sellas Life Sciences,

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