Proliferation index and pseudoprogression as predictors of the therapeutic efficacy of suicide gene therapy for canine melanoma.

Proliferation index and pseudoprogression as predictors of the therapeutic efficacy of suicide gene therapy for canine melanoma. Melanoma Res. 2020 Apr;30(2):126-135 Authors: Fondello C, Agnetti L, Glikin GC, Finocchiaro LME Abstract In our veterinary clinical trials, the combination of systemic immunotherapy with local herpes simplex virus thymidine kinase/ganciclovir suicide gene (SG) treatment induced tumor pseudoprogression as part of a strong local antitumor response. This phenomenon could be owing to tumor inflammation, increased vascular permeability and to different tumor growth rates before, during and after SG therapy. The proliferation index (PI: the fraction of viable cells in S, G2/M, and hyperdiploid phases) would reflect the in-vivo and in-vitro proportion of proliferating melanoma cells in the absence of treatment (PIB) or in response to SG (PISG). The extent of in-vivo and in-vitro melanoma cells responses to SG exhibited a reverse correlation with PIB and a direct correlation with PISG. Then, the final SG outcome depended on the balance between PIB-dependent 'regrowth resistance' versus 'regrowth sensitivity' to SG treatment. In all the cell lines derived from canine tumors presenting partial responses to SG treatment, PISG prevailed over PIB. Conversely, as more aggressive was the tumor (greater PIB of the cell line), the more the balance displacement towards 'regrowth resistance' over SG 'regrowth sensitivity'. Al...
Source: Herpes - Category: Infectious Diseases Authors: Tags: Melanoma Res Source Type: research