Treatment Patterns and Efficacy of Chemotherapy After Pembrolizumab in Advanced Urothelial Cancer-a Real-World Study in the pre-Antibody-Drug Conjugate Era

BACKGROUND: Immune checkpoint inhibitors (ICIs) have been established as a routine treatment in patients with metastatic urothelial cancer (mUC). However, there has been no standard of care after progression on ICIs. We investigated real-world treatment patterns and efficacy of chemotherapy (CHT) after pembrolizumab, in the era before introduction of maintenance avelumab and antibody-drug conjugates (ADC).

PATIENTS AND METHODS: An observational, retrospective study was conducted at twelve Nordic centers. Patients with mUC were treated according to investigator´s choice of CHT after pembrolizumab. Primary endpoint was overall response (ORR) and disease control rate (DCR); secondary endpoints were progression-free (PFS) and overall survival (OS).

RESULTS: In total, 102 patients were included whereof 23 patients received CHT after pembrolizumab as second line treatment (subcohort A) and 79 patients in third line (subcohort B). Platinum-gemcitabine combinations were the most common regimens in subcohort A, and vinflunine in subcohort B. The ORR and DCR were 36% and 47%, respectively. Presence of liver metastases was independently associated with lower ORR and DCR. The PFS and OS were 3.3 months and 7.7 months, respectively. Eastern Cooperative Oncology Group Performance Status (ECOG PS) and number of previous cycles of pembrolizumab were found to be independent prognostic factors associated with OS.

CONCLUSION: In a real-world setting, CHT showed clinically meaningful response rates and survival in mUC patients after progression with pembrolizumab. Clinical benefit may primarily be achieved in patients with favorable ECOG PS, in patients treated with > 6 cycles pembrolizumab as well as in patients without presence of liver metastases.