Immunostimulatory antibodies entering the clinic create challenges not only in terms of pharmacodynamics for monitoring anticipated mechanism but also in pre-determining cytotoxicity. We demonstrate the use of ex-vivo whole blood samples to predict the activation requirements, cytokine signature and adverse events of an anti-human-CD40 chimeric IgG1 antibody, ChiLob7/4. Assessments were initially undertaken on human myeloid (mDC1) and plasmacytoid (pDC) dendritic cells where an absolute need for cross-linking was demonstrated through the up-regulation of activation markers CD83 and CCR7. Subsequent cytokine secretion evaluations of ex-vivo whole blood showed cross-linked antibody induced increases in MIP1β, IL-8, IL-12, TNFα, and IL-6. This cytokine signature compared favorably to the TLR ligand LPS, where levels of TNFα and IL-6 were significantly higher, suggesting a less intense pro-inflammatory response and possible modified cytokine-release-syndrome when used in human trials. Following first-in-human use of this agent within a dose escalation study, in-vivo evaluations of DC activation and secreted cytokines closely matched predetermined immunomonitoring endpoints. Patients showed a comparable pattern of MIP1β, IL-8, and IL-12 secretion but no TNFα, and IL-6 was identified. Mild symptoms relating to a cytokine-release-syndrome were seen at an equivalent dosage to that observed for DC activation and cytokine release. In summary, ChiLob7/4 induces a distinctive pattern of DC activation and cytokine secretion in ex-vivo assays that can be predictive of in-vivo responses. Such pre-clinical approaches to monoclonal antibody evaluation may both inform the starting dosages and anticipated cytokine release events that could occur, providing a valuable adjunct for future first-in-human assessments of immunostimulatory antibodies.
- Received June 5, 2013.
- Revision received October 16, 2013.
- Accepted November 7, 2013.
- Copyright © 2013, American Association for Cancer Research.