A phase 1 trial of SGN-CD70A in patients with CD70-positive, metastatic renal cell carcinoma

Background Cluster of differentiation 70 (CD70) is frequently expressed in renal cell carcinoma (RCC) and has immunomodulatory properties. An antibody-drug conjugate targeting CD70, SGN-CD70A, was developed to treat patients with CD70-positive RCC. Methods The objective of this phase 1, open-label, dose-escalation, multicenter study was to evaluate the safety and tolerability of SGN-CD70A and establish its maximum tolerated dose in patients with CD70-positive, metastatic RCC (mRCC). All subtypes of RCC were permitted, and no limit was set on the number of prior therapies. Safety assessments consisted of monitoring and recording all adverse events (AEs) and dose-limiting toxicities (DLTs). Treatment response was assessed by radiographic tumor evaluation according to the Response Evaluation Criteria for Solid Tumors, version 1.1. A model-based, modified continual-reassessment method was used to estimate the probabilities of DLT and response. Results The maximum tolerated dose was determined to be 30 mu g/kg, with thrombocytopenia as the DLT. The most common AEs were fatigue (67%), anemia (61%), and thrombocytopenia (56%). Of 18 enrolled patients, 1 achieved a partial response and 13 achieved stable disease, for a clinical benefit rate of 78%. Limitations of the study included the heavily pretreated nature of patients, receipt of a median of 4 prior lines of therapy (range, 1-8 prior lines of therapy), and diminishing response potential. Conclusions The modest antitumor activity of SGN-CD70A does not support its development in mRCC. However, given the high disease control rate in a heavily pretreated population and the modest toxicity profile, CD70 remains of interest because of its immunomodulatory properties.