TSR-042 is an anticancer treatment being developed by Tesaro to treat various types of this disease either alone or in combination with other therapies. In ongoing clinical trials, people testing TSR-042 all have advanced or metastatic solid tumors.

It is called an immunotherapy because it uses the body’s own immune system to fight tumor cells.

How TSR-042 works

TSR-042 is an anti-PD-1 drug, which means that it is directed against the PD-1 protein present on the surface of the T-cells, key cells of the immune system.

PD-1 works as an “immune checkpoint,” a protein that regulates the immune response when it is activated by its partner protein, or “ligand,” PD-L1. Although immune checkpoints usually work to maintain a healthy immune system that responds to foreign threats to the body, in some cancers these checkpoints can be “hijacked,” allowing tumors to escape being the target of an immune response and avoid being destroyed by it.

TSR-042 binds to PD-1, blocking the interaction of PD-1 with its ligand PD-L1. This way, the tumor becomes “visible” to the immune system and can be targeted for destruction.

TSR-042 in clinical trials

The first study of TSR-042 in patients started in March 2016, and is recruiting people with metastatic solid tumors in the U.S., Canada, and several countries in Europe. It is a two-part Phase 1 clinical trial (NCT02715284) in people with different advanced-stage cancers and have few treatment options available.  This study is planned to finish in December 2020.

Preliminary safety and effectiveness results from this trial were presented in September at the 2017 ESMO Annual Meeting (Poster 1185P). The investigators reported that 21 patients were included in Part 1, which investigated three doses of TSR-042 (1, 3 or 10 mg/kg every two weeks) to determine which was the best dose to be used in a Phase 2 study. Results showed that TSR-042 was safe and well-tolerated, and the recommended dose was established at 500 mg every three weeks for the first four cycles and 1000 mg every six weeks from then on.

Part 2 is now enrolling advanced cancer patients, and will investigate the safety and effectiveness of this chosen dose in about 435 people with five types of cancer, including endometrial and lung cancer.

A second Phase 1 clinical trial of TSR-042 (NCT03307785) started in October 2017 in the U.S. This study is testing TSR-042 in combination with Tesaro’s Zejula (niraparib) or with CarboTaxol (carboplatin-paclitaxel), a chemotherapy, to establish a safe and tolerable dose of each combination to be used in a Phase 2 trial. The treatment’s efficacy as determined by various response rates in patients, will also be evaluated as secondary endpoints. This study is now recruiting about 66 people with different types of advanced (unresectable or inoperable) or metastatic cancer at six study sites in different states.

More information on both trials is available by clicking on their respective study identification numbers.


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