SATELLITE Study

The SATELLITE Study (feaSibility sAfeTy Efficacy dostarLimab earLy-stage defIcient endomeTrial cancEr) is focused on evaluating the effectiveness and safety of Dostarlimab, a new immunotherapy treatment for patients with early-stage endometrial cancer.

The standard treatment for this cancer typically involves surgery to remove the uterus, fallopian tubes, ovaries, and sometimes lymph nodes. However, this approach may not be ideal for women wishing to preserve fertility or for older women, those with obesity, or individuals with other health conditions that make surgery riskier.

Approximately 20-30% of endometrial cancers are linked to defects in the body’s DNA repair mechanisms, specifically the Mismatch Repair (MMR) pathway. This pathway is responsible for fixing errors during DNA replication, and when it’s defective—known as Mismatch Repair deficiency—unrepaired errors can lead to cancer. Immunotherapy works by helping the immune system recognise and target cancer cells with MMR deficiency.

Dostarlimab is an immunotherapy drug that boosts the immune system, helping it target and attack cancer cells with MMR deficiency. It works by blocking a specific protein in cancer cells, which not only enables the immune system to fight the cancer but also slows tumour growth.

While Dostarlimab is already approved in Australia for treating adult patients with recurrent or advanced MMR-deficient endometrial cancer, it is not currently approved for early-stage cases. The SATELLITE Study will test whether Dostarlimab can be an effective non-surgical treatment for women with early-stage MMR-deficient endometrial cancer—particularly for those who either cannot undergo or do not want surgery, or who wish to preserve their fertility.

This study is the first of its kind to use Dostarlimab in early-stage endometrial cancer. Ten women will participate in a six-month treatment program to determine whether the drug is a safe and effective alternative to surgery, focusing on women who may be unable or unwilling to undergo major surgery. Dostarlimab has shown promise in treating other cancers, such as rectal cancer, but has not yet been tested in early-stage endometrial cancer.

The goals of the study are to determine if Dostarlimab can eliminate cancer, to monitor side effects, assess patients' tolerance, and explore the drug’s impact on fertility. This innovative approach to endometrial cancer treatment may offer a non-surgical option for women with specific genetic traits.

Eligible patients can receive treatment as part of the SATELLITE trial in Brisbane (RBWH), Sydney (Westmead Hospital), and Melbourne (Pater Mac). Results are expected in two years. The treatment regimen includes seven sessions, beginning with four cycles every three weeks, followed by a three-week break, and then three more cycles every six weeks. Total participation spans 12 months.

If successful, this treatment could be approved for wider use, providing more women with a non-surgical alternative to treat early-stage endometrial cancer.