Outcomes of Immune Checkpoint Inhibitor Rechallenge in Advanced Urothelial Carcinoma: Results from a Global Real-World Evidence Study - Beyond the Abstract
Our study addressed this gap using a large, global real-world dataset derived from the TriNetX research network, analyzing outcomes of patients with aUC who received at least two distinct ICI-based treatment courses between 2014 and 2024. Among more than 35,000 ICI-treated patients, only 292 (0.81%) underwent an ICI rechallenge, highlighting how uncommon—and non-standard—this strategy remains in routine practice. Despite its rarity, several clinically meaningful insights emerged. After a median follow-up of 21.7 months from rechallenge, median overall survival (OS) and progression-free survival (PFS) were 20.5 and 10.3 months, respectively. These outcomes suggest that immunotherapy sensitivity may not be universally lost after initial exposure, particularly in selected clinical contexts.
One of the strongest signals from our analysis concerns disease stage at first ICI exposure. Patients who received their first ICI in the non-metastatic setting and were later rechallenged in the advanced setting experienced a markedly longer OS than those treated with both ICIs in the metastatic setting (p<0.0001). This finding likely reflects both favorable tumor biology and patient selection, but it also mirrors real-world clinical scenarios that are becoming increasingly common with the expanding peri-operative use of ICIs.
Timing also appeared to matter. Among patients rechallenged in the metastatic setting, a treatment-free interval of at least 12 months between ICIs was associated with significantly improved OS (p=0.027). In contrast, shorter cut-offs (e.g., 6 months) did not discriminate outcomes, suggesting that durable benefit from the first ICI may be a key prerequisite for successful rechallenge.
An additional hypothesis-generating observation relates to the ICI sequencing strategy. Patients receiving an anti-PD-1 agent after prior anti-PD-L1 therapy achieved the longest median duration of treatment (18.2 months), outperforming both anti-PD-1/anti-PD-1 and anti-PD-L1/anti-PD-1 sequences. Although not definitive, this supports the biological rationale that differences between PD-1 and PD-L1 blockade may translate into clinically relevant effects when switching class rather than re-using the same mechanism.
Importantly, this analysis was not meant to establish ICI rechallenge as a standard of care. Its retrospective nature, reliance on electronic health record coding, lack of centralized radiologic or pathologic review, and absence of detailed toxicity data impose clear limitations. Selection bias and underlying tumor biology likely contribute substantially to the observed outcomes.
Nevertheless, this represents the largest real-world cohort to date evaluating ICI rechallenge in aUC and provides pragmatic guidance for clinicians facing limited options in heavily pretreated patients. Rather than endorsing routine rechallenge, these data help define when it may be reasonable to consider it, particularly in patients with prior durable benefit, long treatment-free intervals, or earlier-stage exposure to immunotherapy.
Ultimately, these findings should be viewed as hypothesis-generating and supportive of prospective trials integrating clinical variables with translational biomarkers—such as circulating tumor DNA or immune profiling—to better identify patients most likely to benefit from immunotherapy rechallenge in the evolving treatment landscape of urothelial carcinoma.
An opinionated perspective: how these data may inform daily practice
From a practical standpoint, these findings reflect a scenario that many clinicians increasingly face but rarely discuss explicitly. In real-world practice, ICI rechallenge is seldom a pre-planned strategy; instead, it can emerge as a pragmatic decision when therapeutic options are limited, patients remain clinically fit, and prior immunotherapy has delivered a durable benefit. In this context, our data do not suggest that rechallenge should be routine, but they do support the idea that it should not be dismissed a priori.
In my view, the key message is not whether ICI rechallenge “works” in general, but in whom it may still make sense. Patients who achieved long-term disease control with a first ICI, particularly when administered at earlier disease stages or followed by a long treatment-free interval, appear biologically distinct from those with early primary resistance. For these selected patients, rechallenge may represent a reasonable option—especially in the absence of contraindications and when other therapies have been exhausted or are poorly tolerated.
Ultimately, these decisions remain individualized and should be made through shared decision-making, balancing potential benefits, prior toxicity, patient preferences, and alternative options.
Written by: Brigida Anna Maiorano, MD, PhD, MSc, Genito-urinary Medical Oncology, IRCCS San Raffaele Hospital, Milan, Italy
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