Diffusion-weighted MRI to determine response and long-term clinical outcomes in muscle-invasive bladder cancer following neoadjuvant chemotherapy

Objective

This study aims to determine local treatment response and long-term survival outcomes in patients with localised muscle-invasive bladder cancer (MIBC) patients receiving neoadjuvant chemotherapy (NAC) using diffusion-weighted MRI (DWI) and apparent diffusion coefficient (ADC) analysis.

Methods

Patients with T2-T4aN0-3M0 bladder cancer suitable for NAC were recruited prospectively. DWI was performed prior to NAC and was repeated following NAC completion. Conventional response assessment was performed with cystoscopy and tumour site biopsy. Response was dichotomised into response (

Results

Forty-eight patients (96 DWI) were evaluated. NAC response was associated with significant increase in mean ΔADC and %ΔADC compared to poor response (ΔADCall 0.32×10-3 versus 0.11×10-3 mm2/s; p=0.009, and %ΔADCall 21.70% versus 8.23%; p=0.013). Highest specificity predicting response was seen at 75th percentile ADC (AUC, 0.8; p=0.01). Sensitivity, specificity, positive predictive power, and negative predictive power of %ΔADCb100 75th percentile was 73.7%, 90.0%, 96.6%, and 52.9%, respectively. %ΔADCb100 75th percentile >15.5% was associated with significant improvement in OS (HR, 0.40; 95% CI, 0.19-0.86; p=0.0179), bCSS (HR, 0.26; 95% CI, 0.08-0.82; p=0.0214), PFS (HR, 0.16; 95% CI, 0.05-0.48; p=0.0012), and time to cystectomy (HR, 0.19; 95% CI, 0.07-0.47; p=0.0004).

Conclusions

Quantitative ADC analysis can successfully identify NAC response and improved long-term clinical outcomes. Multi-centre validation to assess reproducibility and repeatability is required before testing within clinical trials to inform MIBC treatment decision making.

Advances in knowledge

We successfully demonstrated that measured change in DWI can successfully identify NAC response and improved long-term survival outcomes.

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Key Words

• MRI
• diffusion weighted magnetic resonance imaging (DWI)
• imaging biomakers
• muscle invasive bladder cancer (MIBC)
• neoadjuavant chemotherapy

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MESH Headings Collapse

Grants

• 28724 Cancer Research UK

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Affiliation(s)

Shaista Hafeez Division of Radiotherapy and Imaging, The Institute of Cancer Research, London, United Kingdom Urology Unit, The Royal Marsden National Health Service (NHS) Foundation Trust, London, United Kingdom Department of Radiotherapy, The Royal Marsden NHS Foundation Trust, London, United Kingdom
Mu Koh Division of Radiotherapy and Imaging, The Institute of Cancer Research, London, United Kingdom Department of Diagnostic Radiology, The Royal Marsden National Health Service (NHS) Foundation Trust, London, United Kingdom
Kelly Jones Division of Radiotherapy and Imaging, The Institute of Cancer Research, London, United Kingdom Urology Unit, The Royal Marsden National Health Service (NHS) Foundation Trust, London, United Kingdom
Amir El Ghzal Division of Radiotherapy and Imaging, The Institute of Cancer Research, London, United Kingdom Urology Unit, The Royal Marsden National Health Service (NHS) Foundation Trust, London, United Kingdom
James D’Arcy Division of Radiotherapy and Imaging, The Institute of Cancer Research, London, United Kingdom
Pardeep Kumar Urology Unit, The Royal Marsden National Health Service (NHS) Foundation Trust, London, United Kingdom
Vincent Khoo Urology Unit, The Royal Marsden National Health Service (NHS) Foundation Trust, London, United Kingdom Department of Radiotherapy, The Royal Marsden NHS Foundation Trust, London, United Kingdom
Susan Lalondrelle Division of Radiotherapy and Imaging, The Institute of Cancer Research, London, United Kingdom Department of Radiotherapy, The Royal Marsden NHS Foundation Trust, London, United Kingdom
Fiona McDonald Division of Radiotherapy and Imaging, The Institute of Cancer Research, London, United Kingdom Department of Radiotherapy, The Royal Marsden NHS Foundation Trust, London, United Kingdom
Alan Thompson Urology Unit, The Royal Marsden National Health Service (NHS) Foundation Trust, London, United Kingdom
Erica Scurr Department of Diagnostic Radiology, The Royal Marsden National Health Service (NHS) Foundation Trust, London, United Kingdom
Aslam Sohaib Department of Diagnostic Radiology, The Royal Marsden National Health Service (NHS) Foundation Trust, London, United Kingdom
Robert Anthony Huddart Division of Radiotherapy and Imaging, The Institute of Cancer Research, London, United Kingdom Urology Unit, The Royal Marsden National Health Service (NHS) Foundation Trust, London, United Kingdom Department of Radiotherapy, The Royal Marsden NHS Foundation Trust, London, United Kingdom

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Diagnostic performance of contrast-enhanced dynamic and diffusion-weighted MR imaging in the assessment of tumor response to neoadjuvant therapy in muscle-invasive bladder cancer

OBJECTIVES

To evaluate the diagnostic performance of DCE MRI and DWI in the assessment of pathologic complete response (pCR) after neoadjuvant chemotherapy (NAC) in patients with muscle-invasive bladder cancer (MIBC).

METHODS

This prospective study included 90 patients with MIBC who finished NAC. Two radiologists independently assessed MRI for the determination of semi-quantitative parameters (wash-in rate and wash-out rate) and apparent diffusion coefficient (ADC) value. The correlation between pCR and wash-in rate, wash-out rate, ADC value were analyzed. The area under the ROC curve (AUC) was used to evaluate the diagnostic performance for detecting pCR. Inter-reader agreement was assessed using the ICC statistics.

RESULTS

On cystectomy specimens, pCR was confirmed in (43.3%, 39/90). pCR is negatively correlated with wash-out rate (r = - 0.701, p = 0.01) and ADC value (r = - 0.621, p = 0.01). ADC value is positively correlated with wash-out rate (r = 0.631, p = 0.001). The diagnostic accuracy of ADC value (cut-off value: 0.911 × 10^-3mm²/s) and wash-out rate (cut-off value: 0.677 min^-1) in the identification of pCR was (92% for reader 1, 91% for reader 2), and (90% for reader 1, 88% for reader 2), respectively. The sensitivity, specificity for predicting pCR using ADC value + washout rate cut off values were 95.4%, 97.7% for reader 1, and 96%, 97% for reader 2, respectively. AUC was 0.981 for reader 1, 0.971 for reader 2. The overall reproducibility of the mean ADC value and wash out rate was excellent (ICC = 0.83-0.90). The ICC values for the mean ADC value, washout rate was 0.89 (95% CI 0.84-0.89) and 0.87 (95% CI 0.86-0.91), respectively.

CONCLUSION

Semi-quantitative parameter (wash-out) derived from DCE-MRI and ADC has the potential to assess the tumor's complete pathologic response. The two parameters using together can offer the best possibility to identify complete response to NAC in MIBC.

Multiparametric Magnetic Resonance Imaging as a Noninvasive Assessment of Tumor Response to Neoadjuvant Pembrolizumab in Muscle-invasive Bladder Cancer: Preliminary Findings from the PURE-01 Study

BACKGROUND

In the PURE-01 study, pembrolizumab was given preoperatively before radical cystectomy in clinical T2-4aN0M0 patients. An accurate clinical response assessment may be useful for developing new perioperative strategies in these patients.

OBJECTIVE

To evaluate the association between bladder multiparametric magnetic resonance imaging (mpMRI) findings after pembrolizumab and the pathological complete response (CR; pT0).

DESIGN, SETTING, AND PARTICIPANTS

Patients were staged using bladder mpMRI whereby radiologists were asked to characterize the following parameters: residual disease at T1- and T2-weighted images (step 1: yes/no), presence of hyperintense spots within the bladder wall on diffusion-weighted imaging (step 2: yes/no), and presence of pathological contrast enhancement (step 3: yes/no), before and after three cycles of pembrolizumab. Examinations were internally assessed by two senior radiologists and externally evaluated by a third senior radiologist.

INTERVENTION

To evaluate bladder tumor response after neoadjuvant pembrolizumab, mpMRI was used.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

The primary objective was to predict the pT0 after neoadjuvant pembrolizumab by relying on the mpMRI findings. Cohen's kappa statistics was used to assess interobserver variability. Univariable analyses for pT0 were performed including internal and external post-therapy mpMRI steps.

RESULTS AND LIMITATIONS

From February 2017 to October 2018, 82 patients (164 total mpMRI assessments) were analyzed. The agreement between the internal and external mpMRI assessments after therapy was acceptable (κ values ranging from 0.5 to 0.76). Each mpMRI step was significantly associated with pT0 in both internal and external assessments. In patients with CR/no evidence of residual disease (NED) in all internally evaluated mpMRI steps (N = 37), the pT0 was seen in 23 (62%), compared with 19 of 26 externally evaluated NED patients (73%).

CONCLUSIONS

In post-pembrolizumab muscle-invasive bladder cancer, mpMRI sequence assessment had acceptable interobserver variability and represented the basis for the proposal of a radiological CR/NED status definition predicting the pT0 response to pembrolizumab. After validation of these findings with external datasets, we propose this tool for developing bladder-sparing immunotherapy maintenance therapies.

PATIENT SUMMARY

Assessment of the extent of disease in patients with muscle-invasive bladder cancer using conventional imaging yields serious limitations. In the PURE-01 study, we evaluated the potential of bladder multiparametric magnetic resonance imaging (MRI) to predict the pathological complete response to neoadjuvant pembrolizumab. After validation with larger datasets, the proposed stepwise assessment incorporating multiparametric MRI sequences will be used at our center to develop bladder-sparing approaches in future studies.