Abstract
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Objectives Because radiographic imaging patterns of tumor response to oncolytic viruses are not typical of anticancer agents, the addition of FDG PET may improve diagnostic and prognostic power.
Methods Contrast-enhanced CT and FDG PET/CT were performed in pts administered NV1020, in an open-label Phase I/II study. Pts had metastatic colorectal carcinoma and failed chemotherapy. 4 doses of NV1020 were administered weekly by hepatic arterial infusion alone, followed by 2 cycles of systemic chemotherapy. CT and PET were done at screening, after viral infusion, after 2nd cycle of chemotherapy, and every 3 months thereafter. Response was graded by RECIST and EORTC criteria. Post-viral infusion response and later response by CT were correlated with those measured by PET, and each was also correlated with tumor marker response, TTP, and overall survival.
Results 20 patients were enrolled. After viral infusion, 55% showed PD by RECIST and 60% by EORTC criteria. After chemotherapy the PR+SD rate was 75% by CT and 87% by PET. After viral infusion alone, size and SUV increase were noted and correlated weakly with each other (r = .39), but neither correlated with eventual tumor marker response, TTP, or overall survival. Later measurements of imaging response correlated more closely with these clinical response statistics (r = .55-.65) and were more concordant (r = .73).
Conclusions The biological activity of NV1020 manifests as paradoxical increase in size and SUV, likely involving a mechanism of infection/inflammation. These initial imaging changes could actually represent favorable biological activity, but are not distinguishable from tumor progression using current standard CT and PET.
- © 2009 by Society of Nuclear Medicine