ONCOS-102, an experimental immunotherapy vaccine, showed promising results for malignant pleural mesothelioma patients at the 21-month mark of a clinical trial.

Patients receiving ONCOS-102 and chemotherapy had a median overall survival of 20.5 months, compared to a median overall survival of 13.5 months for control group patients receiving chemotherapy only, according to Targovax ASA, the vaccine’s developer. This survival benefit is also an improvement over the 18-month follow-up showing a median overall survival rate of at least 18.2 months among experimental group patients. The latest good news about ONCOS-102 comes just days after the FDA granted Fast-Track Designation to the therapy, which could lead to faster regulatory approval.

What is ONCOS-102?

ONCOS-102 is an adenovirus-based cancer therapy that Targovax developed to treat patients with solid tumors, such as mesothelioma. Adenovirus-based vaccines have traditionally been used to treat diseases such as HIV and tuberculosis, and they’re now being used to treat cancer. They work by targeting specific types of cells in the body and triggering an immune response that helps the body to destroy those cells.

ONCOS-102 is designed to enter tumor cells and kill them. It not only directly attacks cancer cells, but also triggers the immune system to fight tumors. ONCOS-102 is engineered to replicate inside cancer cells and leave healthy cells unharmed.

ONCOS-102 and Mesothelioma

Following successful experiments in mice, ONCOS-102 was cleared for clinical trials. Two mesothelioma patients were included in a Phase I trial testing ONCOS-102 as a single agent (without chemotherapy). Both mesothelioma patients showed immune activation. One of the patients had a 47% reduction in tumor volume 6 weeks after trial completion. The patient went on to live for 18 months—far longer than expected.

Targovax next initiated a clinical trial combining ONCOS-102 with pemetrexed/cisplatin. Thirty-one patients with non-operable malignant pleural mesothelioma were selected. Data from the study indicates that patients tolerate the therapy well. At the 12-month follow-up, patients had a survival rate of 64%. At the 18-month follow-up, more than half of the patients were still alive. Continued survival benefit was shown at the most recent 21-month follow-up.

“It is most encouraging that survival continues to track so well in the ONCOS-102-treated first line group,” said Dr. Magnus Jäderberg, Chief Medical Officer of Targovax. “We have earlier seen and reported how ONCOS-102 drives profound remodeling of the tumor microenvironment. It is now becoming clear that this is translating into long-term survival benefit.”

More Clinical Trials Planned for ONCOS-102 and Mesothelioma

Targovax announced in June 2020 that it is planning a new mesothelioma clinical trial to test ONCOS-102 in combination with immunotherapy drug Keytruda and chemotherapy. Keytruda is FDA-approved for certain mesothelioma patients. If combining the two immunotherapy drugs proves to be effective, it could lead to a new standard of care for treating mesothelioma.

There is a high medical need for novel mesothelioma treatments. Surgery is possible for some patients, but often only when their cancer is detected early. Because mesothelioma is difficult to diagnose—and is often diagnosed at a late stage—treatment options are typically limited.

Last year, the FDA approved Opdivo (nivolumab) in combination with Yervoy (ipilimumab) for the first-line treatment of adults with malignant pleural mesothelioma that cannot be removed by surgery. Opdivo/Yervoy was the first mesothelioma drug regiment approved in 16 years. Before then, the only FDA-approved drug regimen for pleural mesothelioma was pemetrexed/cisplatin chemotherapy.

The FDA granted ONCOS-102 Fast-Track designation for malignant pleural mesothelioma on February 15, 2021 based on its encouraging initial results. Fast-Track drugs are those with potential to address unmet medical needs. With validation from the FDA, ONCOS-102 is on track to provide an important new tool for improving mesothelioma prognosis.

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