Background: Immune checkpoint blockade targeting programmed cell death ligand-1 (PD-L1)/programmed death-1 (PD-1) signaling was approved recently for locally advanced and metastatic urothelial bladder carcinoma (UBC). Some patients experience a very rapid tumor progression, rather than clinical benefit, from anti-PD-L1/PD-1 therapy.
Case presentation: A 58-year-old male diagnosed with non-muscle-invasive bladder cancer 3 years ago received transurethral resection of bladder tumor (TURBT) and intravesical chemotherapy. TURBT was repeated a year later for recurrent and progressive UBC. Following further disease progression, he received a radical cystectomy (RC), pathologically staged as T2bN2M0, and adjuvant cisplatin-containing combination chemotherapy. When his disease progressed to metastatic UBC, he was started on anti-PD-L1 monotherapy and experienced ultrarapid disease progression within 2 months; imaging scans ruled out pseudoprogression. We observed a fourfold increase in tumor growth rate, defined as the ratio of post- to pretreatment rates. Next-generation sequencing of formalin-fixed paraffin-embedded RC tissues showed MDM2  amplification without MDM4  amplification, EGFR  aberrations, or DNMT3A  alterations. Immunohistochemistry showed grade 2+ PD-L1 labeling intensity of the RC tissues, with 15%–25% and 5%–10% PD-LI immunopositive tumor cells and tumor-infiltrating immune cells, respectively.
Conclusion: Even in cases with PD-L1-positive tumors, MDM2  gene amplification may result in failure of anti-PD-L1 immunotherapy and rapid tumor growth. Therefore, genomic profiling may identify patients at risk for hyperprogression before immunotherapy.
Keywords: urothelial bladder carcinoma, programmed cell death ligand-1, immune checkpoint blockade, hyperprogression, MDM2