medwireNews: Treatment with immune checkpoint inhibitors (ICIs) may improve the overall survival (OS) of people with metastatic small-cell urothelial cancer (SCUC), suggests a chart review.
“Although clinical trials remain difficult in these rare variants, further prospective studies are indicated to confirm this finding,” commented Omar Alhalabi and co-researchers from The University of Texas MD Anderson Cancer Center in Houston, USA, in a poster presented at the 2021 ASCO Annual Meeting.
The investigators identified 102 patients who received systemic therapy for metastatic SCUC at their institution between April 2006 and June 2020. The median age of the patients was 66 years, 85% were men, and 45% had previously undergone cystectomy or nephroureterectomy. The most common histology was predominant SC features, in 50%, followed by focal SC features (27%), pure SC (20%), and mixed with large-cell component (2%).
Thirty-eight percent of the patients received ICIs during their disease course, with the majority (74%) receiving ICIs after frontline chemotherapy, while 13% each received ICIs alongside first-line chemotherapy or as the first-line option. Most (79%) received either an anti-PD-1 or an anti-PD-L1 agent as monotherapy.
Receipt of ICI at any time during the disease course was associated with a significant 55% reduction in the risk for death in this cohort. The median OS duration was 20.1 months for patients who received ICIs and 12.0 months for those who received chemotherapy alone.
The findings were similar when the analysis was restricted to patients with de novo metastatic SCUC, such that the risk for death was a significant 72% lower for the 13 patients who received ICIs at any time than for their 23 counterparts who received chemotherapy. The median OS was not reached and 9.4 months, respectively.
Omar Alhalabi and colleagues highlighted that the presence of liver metastases appeared to be associated with poor survival regardless of ICI use. Specifically, median OS was shorter for the 11 ICI-treated patients with liver metastases than for the 28 patients without, at 13.1 versus 21.6 months, albeit without reaching statistical significance.
Discussing the results, the investigators noted that previous research has shown that SCUC tumors are “characterized by the virtual absence [of] PD-L1 expression, and an immune cell density that is three times less than urothelial carcinomas, suggesting ‘immune-exclusion’.”
They also drew attention to the key limitations of the study, such as the retrospective nature of the analysis, and the heterogeneity with respect to the histologies and the use of ICIs in different lines of therapy.
Nonetheless, the current analysis provides clinical data pointing to the benefit of ICI treatment in patients with metastatic SCUC, concluded the team.
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This independent news story was supported by an educational grant from Pfizer and Merck Healthcare KGaA, Darmstadt, Germany