Developmental History, Clinical Considerations, and Future Perspectives

Michael A. Postow, MD; Jedd D. Wolchok, MD, PhD


The Melanoma Letter. 2012;30(1):1-4. 

In This Article

Rethinking Radiographic Disease Assessment: The Immune-related Response Criteria

In addition to the unique side effect profile, ipilimumab is associated with novel patterns of clinical response, distinct from those observed with traditional cytotoxic chemotherapy. Cytotoxic chemotherapy typically is characterized by prompt responses. The "Response Evaluation Criteria in Solid Tumors" (RECIST) criteria were developed to standardize assessment of responses to chemotherapy in clinical trials. Patients treated with ipilimumab, however, experience alternative patterns and kinetics of response. In some cases, patients may have a period of early apparent disease progression before a profound disease response, or regression of initial lesions despite development of additional, smaller lesions.

A study evaluating the novel patterns of disease responses to ipilimumab across three phase II studies determined that improved survival was associated with a variety of radiographic response patterns.[7] Consequently, the immune-related response criteria (irRC) were proposed to evaluate the benefits of ipilimumab and other related immunotherapeutic approaches. In general, the irRC considers the patient's "total tumor burden" and requires confirmation of suspected disease progression with a subsequent radiographic test, approximately four weeks later. IrRC are already being used in tandem with traditional response criteria, such as RECIST, in current clinical protocols for prospective validation of immunotherapeutic agents such as ipilimumab.


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