In particular, Dr. Panebianco noted that there currently are no available tools to select patients who are more likely to respond to neoadjuvant chemotherapy. However, responders, particularly those with a pathologic complete response (pT0N0), had significantly improved survival. Thus, there is an important role for imaging to (1) select “potential responders” and (2) to evaluate the clinical complete response (cCR) prior to consolidative treatment.
Dr. Panebianco emphasized that to allow for sequential assessment of treatment response, the imaging technique needs to be the same pre- and post-therapy. Further, to have clinical utility, radiologic restaging should be comparable to pathological restaging.
She emphasized that the superior contrast and spatial resolution of MRI make it ideally suited for this use. She highlighted data showing that, among 30 patients with bladder cancer receiving chemotherapy, k-means clustering of dynamic contrast-enhanced MRI could partition each bladder tumor into three clusters. Changes of all three cluster VFs were associated with tumor response to chemotherapy. Further, an MRI-based multiparametric radiomics approach led to quite high area under the receiver operative curve for the preoperative grading of bladder cancer. Together, these data support the predictive value of bladder MRI.
In the context of bladder cancer staging, Dr. Panebianco highlighted the use of multi-parametric MRI with the VI-RADS score to define the risk of muscle invasion, prior to TURBT. On a five-point scale, the VI-RADS score provides an assessment ranging from 1:muscle invasion is highly unlikely to 5:invasion of muscle & beyond is highly likely.
Finally, Dr. Panebianco emphasized that MRI, in particular the DWI sequencing, may be helpful in determining pathologic complete response with a high specificity (92%) though sensitivity was not as high (57%), though the overall accuracy was 80%. Further, dynamic contrast enhancement may be helpful in distinguishing residual tumor from treatment effect.
In the PURE-01 study, the authors utilized multiparametric MRI to assess pathologic complete response following immunotherapy with pembrolizumab, finding that the AUC was 0.76 in internal validation and 0.74 in external validation.
Dr. Panebianco suggested that risk stratification of patients with MRI following initial systemic therapy may allow for tailored, personalized therapy.
Presented by: Valeria Panebianco, MD, University of Rome La Sapienza
Written by: Christopher J.D. Wallis, Urologic Oncology Fellow, Vanderbilt University Medical Center Contact: @WallisCJD on Twitter during the 2021 American Society of Clinical Oncology Genitourinary Cancers Symposium (#GU21), February 11th-February 13th, 2021