While rates of most other cancers have declined or plateaued, the incidence and mortality rate of endometrial cancer continue to rise.1 The landscape of endometrial cancer treatment has evolved quickly over the past 2-3 years. While surgery and radiation therapy remain the mainstay of treatment for early-stage disease, the development of multiple targeted therapeutics has led to additional treatment options in advanced-stage disease and more aggressive tumor types, which are both associated with a poorer prognosis.
UNC Chapel Hill
Dr. Jennifer Haag
In this update, we highlight the recent advances in these targeted therapies in endometrial cancer. We review the landmark NRG-GY018 and RUBY trials, which demonstrated that checkpoint inhibitors improve outcomes in women with advanced endometrial cancer. We discuss an immunotherapy and antivascular endothelial growth factor (VEGF) combination useful in certain tumors lacking biomarker expression. We also highlight progress against endometrial cancers that overexpress human epidermal growth factor receptor 2 (HER2), demonstrated in the DESTINY PanTumor-02 trial.
PD-1 inhibitors
Programmed cell death protein 1 (PD-1) is an inhibitory receptor expressed on T cells that binds to programmed cell death ligand 1 (PD-L1). PD-L1 is expressed on many immune cells but can also be expressed on tumor cells. The interaction of PD-L1 expressed on the surface of endometrial cancer cells with the PD-1 receptor on T cells results in diminished T-cell function, eliminating the immune system’s ability to attack the tumor cells. Treatment with a PD-1 inhibitor prevents this ligand-receptor interaction and restores cancer-fighting function to T cells.
Dr. Katherine Tucker
Pembrolizumab, an antibody against the PD-1 receptor, has been used as single-agent treatment for recurrent endometrial cancer since the KEYNOTE-158 study demonstrated clinical benefit in patients with mismatch repair deficient (dMMR) tumors.2
Additionally, in 2022, Makker et al. published results from a phase 3 trial3 evaluating immunotherapy in the treatment of recurrent endometrial cancer, specifically in patients with mismatch repair proficient (pMMR) tumors. They compared the combination of pembrolizumab and lenvatinib, an oral inhibitor of VEGF, to physician’s choice next-line chemotherapy in over 800 patients with advanced or recurrent endometrial cancer. They found that progression-free survival (PFS) was significantly improved from a median of 3.8 months with chemotherapy to a median of 6.6 months with pembrolizumab and lenvatinib in the pMMR population. Overall survival was also improved from 12 months to 17.4 months in the pMMR population.
With the clear benefit of immunotherapy in the recurrent setting established, Eskander and colleagues were the first to evaluate treatment with pembrolizumab as upfront treatment in the NRG-GY018 trial,4 comparing standard first-line chemotherapy (carboplatin and paclitaxel) with or without the addition of pembrolizumab. This randomized, international, phase 3 trial included over 800 patients with advanced or recurrent endometrial cancer of any histology except carcinosarcoma. Patients received carboplatin and paclitaxel with either pembrolizumab or placebo, followed by maintenance pembrolizumab or placebo. The results showed an improvement in PFS with the addition of immunotherapy, with a risk of disease progression or death with pembrolizumab 70% lower than with placebo in patients with dMMR tumors and 46% lower than with placebo in patients with pMMR tumors.
In the similar randomized, international, phase 3 RUBY trial,5 Mirza and colleagues compared standard chemotherapy with or without the addition of another PD-1 inhibitor, dostarlimab, in almost 500 patients with advanced or recurrent endometrial cancer of any histology. They found that the addition of dostarlimab to standard chemotherapy significantly improved PFS. Unpublished data presented at the Society of Gynecologic Oncology annual meeting in March also demonstrated an improvement in overall survival.6 As in NRG-GY018, they found a substantial benefit again in the dMMR population.
The results of these three landmark trials demonstrate the increasing role for immunotherapy in endometrial cancer, especially at the time of initial treatment, and how biomarkers can help direct treatment options.