About this Research Topic
Although used in most oncological settings, the only standardized response evaluation criteria, RECIST 1.0 and RECIST 1.1, are dependent on the morphological changes measured in two dimensions and lack full assessment of tumor burden in three dimensions. Moreover, response categories defined in RECIST are more rigid and based on the working hypothesis that lesion progression is unidirectional and fixed, which is often contrary to the working principle of treatment with some targeted drugs. Morphological changes induced by targeted drugs, detected by CT or MRI, are often preceded by molecular and histopathological changes. The differences between molecular/histopathological changes and anatomical changes measured by CT/MRI become significant for drugs acting via direct and indirect interaction with cancer cells, microenvironment and tumor immunity. The phenomenon such as pseudoprogression may result in the dynamicity of responses measured on CT or MRI.
Radioligand therapy (RLT) has recently taken a center stage in the management of neuroendocrine tumors and prostate cancer through beta or alpha particle emitting radiolabeled probes (RP). RP have also shown excellent results in other solid tumor and hematological cancers prompting new treatment strategies tested in phase II / Phase III studies. Just like for immunotherapies for RLT, RECIST 1.1 or RECIST 1.0 also do not take into consideration the aforementioned issues in response evaluation.
Analogous to immunotherapy, in view of the rapid development in theranostics with RP and several phase II / phase III studies, it is essential to propose and assess new response evaluation criteria for RLT both in prospective settings as well as through retrospective data mining.
In this Research Topic, we welcome include Original Research and Review articles that address the following aspects of newly proposed response evaluation criteria:
1) Disease progression (confirmation of disease progression)
2) Pseudoprogression (flare)
3) Delayed response
4) Definition and characterization of new lesions (also including PET/CT or PET/MRI)
5) Cystic lesions
6) Correct representation of tumor burden
7) Bone lesions (confirmation with PET/CT or PET/MRI)
8) Timing of response assessment (interim, early, late)
9) Resetting the bar for taking a patient off RLT in a patient otherwise showing no toxicity and showing clinical and biochemical benefit
10) Integrate the need for image-based tumor characterization, especially in the scenario of ambiguous lesions / equivocal progress.
11) Integration of surrogate biomarkers and PET-based response parameters in CT / MRI based RECIST
Keywords: Radioligand therapy, response assessment, surrogate markers, NET, prostate cancer
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