VG Life Sciences Inc. (VGLS)

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CCR 20th Anniversary Commentary: Immune-Related Response Criteria—Capturing Clinical Activity in Immuno-Oncology

http://clincancerres.aacrjournals.org/content/21/22/4989.full

With the advent of immuno-oncology triggered by the approval of ipilimumab in 2011 (1), a broad wave of new cancer drugs is being developed that function differently than chemotherapies or targeted therapies. While the latter induce direct cytotoxic effects on cancer cells, immunotherapies target the immune system and exert indirect effects on tumors with distinct characteristics in the clinic. Such characteristics include the fact that (i) immune activation can take time and may lead to a delay in onset of clinical effects; (ii) T cells recruited to tumors may increase tumor volume before they can shrink it; and (iii) the interplay between the immune system and the tumor may be a long-term dualistic process with slow and possibly undulating clinical effects.

Outlook

Going forward, the expanding spectrum of immuno-oncology modalities under investigation will further increase the complexity of clinical activity patterns. Current modalities are checkpoint modulators (e.g., ipilimumab, pembrolizumab, nivolumab, atezolizumab, and durvalumab), bispecific antibodies (e.g., blinatumomab), oncolytic viruses (e.g., T-vec), various types of cancer vaccines, cytokines, and cellular therapies (e.g., CAR-Ts or TCR-Ts), among others. Some of these agents will induce high conventional response rates and others will not. As was evidenced by ipilimumab, a 10% conventional response rate can translate into 20% to 25% of long-term survival via additional patterns of clinical activity that convey survival benefit (1, 6). Every new modality will likely carry its own clinical activity profile, which can only be understood with tools able to capture them, such as irRC.

irRC will continue to evolve. The advances described here allow for modification of the criteria for clinical protocol applications, as is routine for other criteria (e.g., mRECIST). A next important step will be the adjustment to hematologic malignancies, in which immunotherapies are beginning to demonstrate substantial benefit (15). Throughout this evolution of irRC, particular attention will need to be paid to aspects directly influencing patient management, including (i) selecting time points for disease assessments (especially the first assessment) that align with the natural course of the cancer under investigation; (ii) defining progression and the duration of follow-up for response after progression; (iii) discontinuation criteria for investigational immunotherapy; and (iv) accounting for delayed effects relative to any postprogression therapies. Each of these aspects can be included in subsequent versions of irRC or be specified in clinical trial protocols.