RECIST disease assessment is effective for targeted treatment as well as classical chemotherapy

Assessing tumour growth and cancer cell proliferation in patients is important both for judging the effectiveness of individual treatment and for the evaluation of therapies in clinical trials. EORTC was among the international organisations that developed RECIST (Response Evaluation Criteria in Solid Tumours), a method of determining whether tumour measurement data can allow the conclusion that a patient’s disease has improved, stayed about the same, or worsened
First published in 2000, the RECIST criteria for disease assessment are now used across the world. But today cancer patients are increasingly treated with targeted cancer agents (TCAs), a relatively new class of drug that block the growth and spread of cancer by interfering with specific molecules involved in tumour growth. They differ from classical chemotherapy in that they interact with a specific target to block the proliferation of tumours, while classic chemotherapy kills all rapidly dividing cells. Would the latest version of RECIST (1.1) be equally effective in evaluating response to TCAs ? The EORTC RECIST Working Group set out to find out.

«RECIST is a very important yardstick and gives us good reliability in the comparison and assessment of clinical trial results, as well as a common understanding of the terms used to describe disease improvement, stability, and progression, » says Dr Jan Bogaerts, Scientific Director at the EORTC headquarters. «It was therefore important for us to know whether it would give us reliable results for patients who are treated with TCAs.»
Because the mechanism of action of TCAs is different, researchers were concerned that RECIST evaluations might not be appropriate in such treatment because, for example, different tumours within the same patient could react differently to the TCA due to heterogeneous characteristics. A large database was therefore necessary in order to be sure of robust conclusions in any investigation. The EORTC RECIST Working Group compiled a database on the basis of 50 Phase II and Phase III trials containing data from patients treated with TCAs alone or in combination with chemotherapy.

«Our study looked at the data of over 23,000 patients with cancer, more than 17,000 of whom received treatment with TCAs. To our knowledge, this is the largest individual patient database to date with detailed tumour response measurements for patients treated with TCAs,» says Dr Bogaerts.

The researchers then selected target lesions for a detailed study of response to treatment according to the RECIST criteria. «The results were similar across all tumour types and for different classes of TCAs,» says Dr Bogaerts, «and show that a RECIST1.1 evaluation is as valid for tumours treated with TCAs as it is for classical chemotherapy.»
Immunotherapy drugs were not included in the study because not enough data were available at the time. However, the RECIST Working Group has recently developed ‘iRECIST’, consensus guidelines to enable the evaluation of tumour response to immunotherapy treatment. «This was developed after extended consultation with the research and pharmaceutical community,» says Dr Bogaerts. « Many trials are now using this method, and we will evaluate its effectiveness as data become available. The Working Group endeavours to regularly update RECIST, and we look continuously for new areas where it can be useful and relevant. »

The research is published in the Journal of Clinical Oncology