The combination of an mTOR complex 1 inhibitor (everolimus) plus a VEGF inhibitor (bevacizumab) showed promise against advanced non–clear cell renal cell carcinoma characterized by papillary features in a small manufacturer-sponsored phase II trial, according to a report published online Sept. 6 in the Journal of Clinical Oncology.
Non–clear cell renal cell carcinomas (ncRCCs) are a diverse mixture of heterogeneous malignancies and include papillary, chromophobe, medullary, collecting duct, and a variety of unclassified tumor types. Researchers performed a single-center trial to assess the effectiveness of combined everolimus plus bevacizumab in 35 treatment-naive patients who presented with advanced disease representing all of these histologic types. The unclassified subgroup (23 patients) included several tumors with prominent papillary architectural features that did not fulfill other criteria for papillary RCC, said Martin H. Voss, MD, of Memorial Sloan Kettering Cancer Center, New York, and his associates.
Dr. Martin H. Voss
A total of 18 patients (53%) were alive and free of disease progression at 6 months, and 10 (29%) were alive and progression free at 12 months. Two patients still were receiving study treatment at the time of publication, after 20.2 and 30.4 months of therapy, respectively.
“Objective responses were observed in a sizable proportion of subjects with significant papillary (7 of 18) or chromophobe (2 of 5) tumor components but rarely in patients with unclassified RCC without papillary features (1 of 9) or those with medullary RCC (0 of 2),” Dr. Voss and his associates reported. Among patients with unclassified RCC, the 14 whose cancer had a major papillary component showed an objective response rate of 43%, a median progression-free survival of 12.9 months, and a median overall survival of 28.2 months. In contrast, the nine patients whose cancer did not have a major papillary component showed an objective response rate of 11%, a median progression-free survival of 1.9 months, and a median overall survival of 9.3 months, the investigators said (J Clin Oncol. 2016 Sept 6. doi: 10.1200/JCO.2016.67.9084).
Treatment was generally well tolerated, even though there were frequent low-grade toxicities. High-grade toxicities known to be associated with mTOR complex 1 inhibitors or VEGF inhibitors included hyperglycemia (11%), hypertriglyceridemia (14%), lymphopenia (20%), hypertension (29%), and proteinuria (18%). There were two patient deaths from gastrointestinal hemorrhage, one of which was considered possibly related to bevacizumab.
Archived tissue samples were available for genetic analysis for some patients. Acquired mutations in the ARID1A gene were noted in 5 of 14 tumors with major papillary components, and all 5 of those patients achieved more than 6 months of progression-free survival with the combination therapy. In contrast, no ARID1A mutations were detected in any of the patients who had shorter progression-free survival, and none were detected in any of the tumors that did not have papillary components. This suggests that ARID1A “merits further study for its functional role in papillary RCC variants and as a candidate biomarker for future study of everolimus plus bevacizumab,” Dr. Voss and his associates said.
Novartis supported the study. Dr. Voss reported ties to Novartis, Calithera Biosciences, Natera, GlaxoSmithKline, Exelixis, Pfizer, Bristol-Myers Squibb, Genentech, and Takeda; his associates reported ties to numerous industry sources.