According to independent review, 25 (47%) of 53 patients had objective responses—a high proportion compared with those reported for standard-of-care chemotherapy regimens or endocrine therapy. The proportion of patients with objective responses in this interim analysis seems higher than that reported with pembrolizumab (13% 95% CI 2·8–33·6%) or lenvatinib (14·3%) monotherapy in patients with advanced endometrial cancer.2,6 Although non-randomised phase 2 studies that do not have an unbiased treatment comparator group consisting of patients from the same population are at risk of bias because of their small sample size and patient selection (ie, unintentional enrolment of patients with favourable characteristics), the activity of lenvatinib and pembrolizumab in microsatellite-stable endometrial cancer is promising enough that the combination clearly warrants further assessment in randomised phase 3 studies. Notably, in mouse models, the combination of lenvatinib with a monoclonal antibody with activity against PD-1 resulted in greater anti-tumour activity than either agent alone.7 Furthermore, co-inhibition of VEGF and PD-1 signalling could be an effective strategy to improve immunotherapy because VEGF modulates anti-tumour immunity by inducing proliferation of suppressive regulatory T cells, and VEGF inhibition in turn can decrease the number of regulatory T cells.8 VEGF can also promote the expansion of myeloid-derived suppressor cells9 and limit the maturation of dendritic cells capable of presenting tumour antigens and inducing a T-cell response.10 Modulation of a VEGF-mediated immune suppressive state in the tumour microenvironment through inhibition of angiogenesis could be an effective strategy to improve the clinical activity of PD-1 inhibition in endometrial cancer, irrespective of the tumour's microsatellite status.