Case Report: early regression and bladder-intact survival after limited-course immunotherapy-based systemic therapy in two patients with clinically staged bulky muscle-invasive bladder cancer.

BACKGROUND

Radical cystectomy remains a standard curative treatment for muscle-invasive bladder cancer (MIBC). Bladder preservation after systemic therapy without immediate surgery remains investigational and requires careful patient selection, rigorous reassessment, and structured surveillance. We report two cases of early tumor regression after limited-course immunotherapy-based systemic therapy, with bladder-intact survival during available follow-up.

CASE PRESENTATION: Two male patients aged 75 and 73 years with clinically staged bulky bladder tumors suspicious for MIBC (one cT3N0M0 and the other at least cT2N0M0) received limited-course PD-1 inhibitor-based systemic therapy without immediate radical cystectomy. Both patients showed marked regression after two treatment cycles: Case 1 received tislelizumab plus platinum-based chemotherapy, and Case 2 received toripalimab plus disitamab vedotin. In Case 2, post-treatment transurethral reassessment and multi-site biopsies showed no definite residual malignancy; one additional cycle was then administered. Radical cystectomy was recommended but declined in both cases. At approximately three years after treatment initiation, no clinically detectable recurrence was identified based on available, non-protocolized assessments, although interval cystoscopic surveillance was incomplete.

CONCLUSION

These cases document unusually early regression after limited-course immunotherapy-based systemic therapy in clinically staged bulky bladder tumors. The findings remain hypothesis-generating and do not justify routine omission of radical cystectomy or abbreviated systemic therapy. Instead, they suggest that early response kinetics may identify exceptional responders who warrant rigorous multimodal reassessment, molecular characterization, and structured surveillance within future response-adapted bladder-preserving strategies.