High Reward, High Toxicity: Combination Pembrolizumab and Lenvatinib in Advanced Endometrial Cancer

The combination of pembrolizumab and lenvatinib is a promising second line option for metastatic or recurrent MSS endometrial cancer, although there can be considerable toxicity and choosing appropriate patients is key.   TRANSCRIPT This JCO Podcast provides observations and commentary on the JCO article "Lenvatinib and Pembrolizumab in Patients With Advanced Endometrial Cancer" by Makker et al. My name is Meghan Shea, and I am an Instructor of Medicine at Harvard Medical School at Beth Israel Deaconess Medical Center in Boston, Massachusetts. My oncologic specialty is gynecologic oncology. Patients with advanced endometrial carcinoma have limited options after receiving the carboplatin and paclitaxel doublet for recurrent or metastatic disease. The study that accompanies this podcast evaluates the combination pembrolizumab and lenvatinib, providing a much needed second-line option for this patient population. The approval of single-agent pembrolizumab for tumors with microsatellite instability (from here on referred to as MSI high) does not have immediate relevance for the majority of patients with advanced endometrial carcinoma who have microsatellite stable disease (from here on referred to as MSS). Makker et al. now report the results of an ongoing phase 1b/2 study of pembrolizumab, an anti-PD1 antibody, and lenvatinib, an oral tyrosine kinase inhibitor that targets the VEGF-receptor, in patients with metastatic endometrial carcinoma. Eligibility criteria included patients with an ECOG 0 to 1 who had confirmed metastatic disease with less than or equal to 2 prior lines of systemic therapy. Notably the majority were not heavily pre-treated; 52.8% of patients in the study had only one prior line of systemic treatment. Patients received lenvatinib 20 mg once daily orally continuously and pembrolizumab 200 mg intravenously every 3 weeks – with a maximum duration of 2 years for pembrolizumab. All patients had imaging at baseline and then every 6 weeks for first 24 weeks and then every 9 weeks thereafter. The primary end point was objective response rate at 24 weeks. Forty-one of the 108 patients, 38%, had a response at 24 weeks with a median follow up of 18.7 months.  As expected, the MSI high tumors had a higher response rate of 63.6%, although this was a minority of the study population, only 11 patients. Most importantly, the patients with MSS tumors had a response rate of 37.2% with a median duration of response of 21.2 months. The histology did not appear to impact the response rate – the majority of patients had endometrioid (50.9%), although the study population also contained a reasonable proportion of serous and clear cell (38%) compared to the expected frequency in the general population of advanced uterine cancers. The PD-L1 status positive or negative did not correlate with response. One might question, before accepting a complicated regimen with both oral and IV chemotherapy as a new second-line standard option, whether anyone has studied the activity of either single agent lenvatinib or single agent pembolizumab in a similar population, especially for those with MSS disease. With the caveats of cross study comparisons, it appears that neither single agent is as active as the current combination. For instance, Vergote et al reported results of a phase 2 study of lenvatinib monotherapy for advanced endometrial cancer, where the response rate was only 14.3% with median progression free survival of 5.4 months. Likewise, Ott et al studied single agent pembrolizumab in endometrial cancer with 18 of 19 patients having MSS cancer, resulting in only a 13% response rate and progression free survival of 1.8 months.              So you may be wondering, what's the catch? The issue is the potential toxicity of this doublet regimen, with 66.9% or 83 of 108 patients, having a grade 3 or 4 treatment-related adverse event. Overall 17.7% of the patients discontinued one or both drugs. Notably, pembrolizumab was never dose reduced - only dose held or discontinued. Most strikingly, 62.9%, roughly two thirds of patients, required a dose reduction of lenvatinib. Only 11 patients (that is 8.9%) stayed on full dose 20 mg of lenvatinib for greater than 6 months. The average dose for lenvatinib was 14.4 mg daily. The toxicity profile of lenvatinib may be related to the fact that it is a multi-targeted tyrosine kinase inhibitor that targets not only vascular endothelial growth factor receptors, but also fibroblast growth factor receptors, platelet-derived growth factor receptor alpha, RET and KIT. There were 51 deaths during this study; the majority occurred during follow up due to progression of disease. However, there were 16 deaths while on study, 4 considered treatment emergent adverse events and 2 judged to be treatment related.  The four deemed treatment emergent were due to gastrointestinal perforation, intestinal obstruction, general health deterioration and metabolic encephalopathy. The two deemed treatment related were from septic shock and intracranial hemorrhage. The National Comprehensive Cancer Network (NCCN) guidelines have added the combination of pembrolizumab and lenvatinib to their list of second line therapeutic options, and it also has been approved by the Food and Drug Administration (FDA). This recognizes the fact that this combination has the highest response rate of the available drugs listed, and thus should be a strong consideration for second line therapy for patients with MSS endometrial carcinoma. However, ensuring that this treatment is appropriate for a given patient is of the utmost importance.  First the patient must be a candidate for immunotherapy – ideally not on chronic prednisone and/or have an active autoimmune disease. In contrast to prescribing single agent anti-PD-1 or anti-PD-L1, a performance status of 0 to 1 is important with this combination. The most appropriate patient should have controlled blood pressure prior to initiating drug, be able to monitor their blood pressures, take their oral chemotherapy as prescribed, and readily report any new symptoms. I avoid prescribing this drug combination if the patient has a bleeding disorder, recent clotting, uncontrolled hypertension, or is at high risk of a fistula or bowel obstruction. Lenvatinib is a renally-cleared drug, and thus patients with a reduced glomerular filtration rate (GFR) require renal dosing. This is especially relevant for patients with recurrent uterine cancer, whose kidney function is dynamic, especially in the setting of hydronephrosis. In my practice, I consider starting patients with normal renal function at 14 mg lenvatinib daily, given that the vast majority of patients on study were eventually dose-reduced. Furthermore, I might start the lenvatinib dosing even lower for patients with dynamic renal function and for those who have a baseline GFR lower than 30. Overall this study provides a promising second line option for metastatic or recurrent MSS endometrial cancer, with responders having a durable response.  Patient selection and dose adjustments are key considerations to avoiding and managing toxicity. This concludes this JCO Podcast. Thank you for listening.