Efficacy and toxicity of antibody-drug conjugates in the treatment of metastatic urothelial cancer: A scoping review

Metastatic urothelial cancer (mUC) is an aggressive disease with limited overall survival and treatment options. Antibody-drug conjugates (ADCs) were designed with the intent to deliver potent cytotoxic drugs selectively to antigen-expressing tumor cells by linking cytotoxins to monoclonal antibodies (mAbs) and have emerged as new treatment options in mUC, mainly in chemotherapy (CT) and immune-checkpoint inhibitors (ICI)-exposed patients. We aimed to perform a scoping review to assess activity, efficacy, treatment-related adverse events (TRAEs), and impact on quality of life of ADCs in mUC.A review of the literature was performed in January 2022 using Pubmed and Embase databases according to the recommendations of the Joanna Briggs Institute. The search method involved querying for the terms "bladder carcinoma" or "urothelial carcinoma" with any of the following: "enfortumab vedotin" (EV), "sacituzumab govitecan" (SG), antibody-drug conjugate. Only prospective clinical trials were included.Ultimately, eleven clinical trials with 1417 patients were selected for inclusion, and five drugs were identified: enfortumab vedotin (EV), sacituzumab govitecan (SG), disitamab vedotin (RC48-ADC), ASG-15ME (anti-SLITRK6), and trastuzumab deruxtecan. The different ADCs have been tested mainly in phase 1 or phase 2 trials, as monotherapy or in combination with ICI. Response rate ranged from 27% with SG in previously treated patients to 73.3% with EV plus pembrolizumab in cisplatin-ineligible patients as first-line treatment. The phase 3 trial, EV-301, confirmed EV superiority over investigator-chosen CT after failure to platinum-based CT and ICI, improving overall survival (12.88 vs. 8.97 months; HR 0.70; 95% CI, 0.56-0.89; P=0.001). TRAEs of any grade occurred in more than 90% of patients in phase 2 or 3 trials, with high rates of grade 3 ≥ events ranging from 51.4 to 73.5% in different trials. TRAEs of particular interest related to EV were rash, neuropathy, and hyperglycemia. SG was associated with diarrhea and hematologic toxicity. Data from phase 2 and 3 trials of EV suggest no impact on quality of life but an improvement in pain symptoms compared to the control arm.ACDs represent a new therapeutic option for the treatment of mUC. Level-1 evidence has already been achieved by EV in the post-CT and post-ICI settings. A high incidence of potential adverse events was observed in phase 2 and 3 trials, including rash, neutropenia, hematologic toxicity, and neuropathy. Clinicians should be aware of possible adverse events and their optimal management.