Imaging Response of Antiangiogenic and Immune-Oncology Drugs in Metastatic Renal Cell Carcinoma (mRCC): Current Status and Future Challenges

Abstract

This report aims to review criteria which have been proposed for treatment evaluation in mRCC under anti-angiogenic and immune-oncologic therapies and discuss future challenges for imagers.RECIST criteria seem to only partially reflect the clinical benefit derived from anti-angiogenic drugs in mRCC. New methods of analysis propose to better evaluate response to these drugs, including a new threshold for size criteria (–10%), attenuation (Choi and modified Choi criteria), functional imaging techniques (perfusion CT, ultrasound or MRI), and new PET radiotracers.Imaging of progression is one of the main future challenges facing imagers. It is progression and not response that will trigger changes in therapy, therefore it is tumour progression that should be identified by imaging techniques to guide the oncologist on the most appropriate time to change therapy. Yet little is known on dynamics of tumour progression, and much data still needs to be accrued to understand it. Finally, as immunotherapies develop, flare or pseudo-progression phenomena are observed. Studies need to be performed to determine whether imaging can distinguish between patients undergoing pseudo-progression for which therapy should be continued, or true progression for which the treatment must be changed.

Feasibility Study on Using Dynamic Contrast Enhanced MRI to Assess the Effect of Tyrosine Kinase Inhibitor Therapy within the STAR Trial of Metastatic Renal Cell Cancer

“…The varying responses of metastatic tumours within the same patient as reflected by the different degrees of change in the perfusion parameters between lesions in the same patient ( Supplementary Materials ) also highlights the complex inter-tumoural heterogeneity in mRCC known to contribute to the heterogeneous clinical outcomes observed in clinical trials [ 20 ]. Functional imaging may allow for further quantification of tumour heterogeneity to help understand tumour progression further in patients undergoing anti-angiogenic therapy before morphological changes in size occur [ 34 ].…”

Blood Volume as a new functional image-based biomarker of progression in metastatic renal cell carcinoma

“…However, immune checkpoint inhibitors may lead to immune cell infiltration in the tumor tissue, resulting in inflammatory swelling, i.e., the tumor lesion increases in size or new lesions appear as part of pseudo-progression 5 . Angiogenesis inhibitors can induce tumor necrosis leading to an increase in size of the tumor 6 . Therefore, when monitoring treatment according to RECIST v1.1, an enlargement in the tumor can lead to interpretational distress over stopping therapy, as the patient may not necessarily have treatment failure.…”