Large phase III study of carbo/taxol+pembro x 6 followed by pembro alone x 14 cycles in metastatic endometrial cancer. There was a benefit in both pMMR and dMMR patients, although the magnitude was unsurprisingly higher in those with dMMR. OS results are still pending, and carcinosarcoma-type histology was excluded. This combination has been approved and is on NCCN as a cat-1 recommendation.
Standard first-line chemotherapy for endometrial cancer is paclitaxel plus carboplatin. The benefit of adding pembrolizumab to chemotherapy remains unclear.
In this double-blind, placebo-controlled, randomized, phase 3 trial, we assigned 816 patients with measurable disease (stage III or IVA) or stage IVB or recurrent endometrial cancer in a 1:1 ratio to receive pembrolizumab or placebo along with combination therapy with paclitaxel plus carboplatin. The administration of pembrolizumab or placebo was planned in 6 cycles every 3 weeks, followed by up to 14 maintenance cycles every 6 weeks. The patients were stratified into two cohorts according to whether they had mismatch repair–deficient (dMMR) or mismatch repair–proficient (pMMR) disease. Previous adjuvant chemotherapy was permitted if the treatment-free interval was at least 12 months. The primary outcome was progression-free survival in the two cohorts. Interim analyses were scheduled to be triggered after the occurrence of at least 84 events of death or progression in the dMMR cohort and at least 196 events in the pMMR cohort.
In the 12-month analysis, Kaplan–Meier estimates of progression-free survival in the dMMR cohort were 74% in the pembrolizumab group and 38% in the placebo group (hazard ratio for progression or death, 0.30; 95% confidence interval [CI], 0.19 to 0.48; P<0.001), a 70% difference in relative risk. In the pMMR cohort, median progression-free survival was 13.1 months with pembrolizumab and 8.7 months with placebo (hazard ratio, 0.54; 95% CI, 0.41 to 0.71; P<0.001). Adverse events were as expected for pembrolizumab and combination chemotherapy.
In patients with advanced or recurrent endometrial cancer, the addition of pembrolizumab to standard chemotherapy resulted in significantly longer progression-free survival than with chemotherapy alone. (Funded by the National Cancer Institute and others; NRG-GY018 ClinicalTrials.gov number, NCT03914612. opens in new tab.)
For patients with local recurrences of endometrial cancer, XRT alone is extremely effective, and the addition of cisplatin does not offer any benefit while increasing toxicity. These patients with low-grade and vaginal recurrences have a good prognosis and most should be treated with XRT alone.
Initial results from the DUO-E study in metastatic endometrial cancer. The preliminary report suggests that maintenance durvalumab and maintenance durvalumab + olaparib were superior to standard observation after systemic carbo/taxol. As the trial data matures, the question will be: is this in all patients or driven by those with dMMR or HDR mutations?
This is another possibility for maintenance therapy. It will require further study.
An interesting study where the authors performed a post hoc analysis of randomized trials using molecular classification of endometrial cancers. There was good evidence to omit RT for those with POLE mutations and def-MMR. There seems to be a higher degree of benefit in those with a p53 mutation.
Chemo + IO may become the SOC for 1L treatment of met-endometrial adenoCa. For pembro + chemo, there was a 70% lower risk of disease progression in dMMR and a 46% lower risk in pMMR compared to placebo + chemo. For pMMR patients, the impact on 2L therapy responses will need to be considered carefully, as lenvantinib + pembro has been found to be superior to either agent alone after chemo.
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