ASCO 2021: Bladder-Sparing Combination Therapy Under Study in Muscle-Invasive Urothelial Cancer
Posted: Tuesday, June 8, 2021
During the 2021 American Society of Clinical Oncology (ASCO) Annual Meeting, Arjun Vasant Balar, MD, of the Perlmutter Cancer Center at NYU Langone Health, New York, and colleagues presented their safety and efficacy results with pembrolizumab plus gemcitabine and concurrent hypofractionated radiation therapy as a potential bladder-sparing treatment in muscle-invasive urothelial cancer of the bladder (Abstract 4504). In addition, the researchers concluded that this combination treatment was not only well tolerated, but the toxicity profile was consistent with that of prior monotherapy trials.
This phase II trial enrolled 54 patients with clinical stage II to stage IV, nonmetastatic muscle-invasive urothelial cancer of the bladder ineligible for or declined cystectomy. Participants received 200 mg of pembrolizumab, followed 2 to 3 weeks later with transurethral resection of bladder tumor, then whole-bladder radiotherapy with 27 mg/m2 of gemcitabine and pembrolizumab. After 12 weeks, CT, MRI, and transurethral resection of the tumor bed and cytology were performed.
The median age of patients in the safety cohort was 67 (n = 6), and the median age of patients in the efficacy cohort was 74 (n = 48). A majority of patients had clinical stage II (74%) disease, followed by stages III (22%) and IV (4%). All individuals in the safety cohort and 42 participants in the efficacy cohort completed study therapy; most of the remaining patients discontinued treatment due to toxicity.
As of January 2021, there were no recurrences in the safety cohort, but 12 recurrences were reported in the efficacy cohort. The estimated 1-year bladder-intact disease-free survival rate was 77%, and the 12-week complete response rates were 100% and 83% for the safety and efficacy cohorts, respectively.
About 35% of patients in the efficacy cohort experienced grade 3 or greater treatment-related adverse events such as urinary tract infection, colitis, bladder pain/obstruction, diarrhea, thrombocytopenia, and neutropenia. In addition, grade 3 gastrointestinal toxicity occurred in three patients, and grade 4 colonic perforation was detected in one patient.
Disclosure: For full disclosures of the study authors, visit coi.asco.org.