Adapted ECHO-7 virus Rigvir immunotherapy (oncolytic virotherapy) prolongs survival in melanoma patients after surgical excision of the tumour in a retrospective study

Abstract

An oncolytic, nonpathogenic ECHO-7 virus adapted for melanoma that has not been genetically modified (Rigvir) is approved and registered for virotherapy, an active and specific immunotherapy, in Latvia since 2004. The present retrospective study was carried out to determine the effectiveness of Rigvir in substage IB, IIA, IIB and IIC melanoma patients on time to progression and overall survival. White patients (N=79) who had undergone surgical excision of the primary melanoma tumour were included in this study. All patients were free from disease after surgery and classified into substages IB, IIA, IIB and IIC. Circulating levels of clinical chemistry parameters were recorded. Survival was analysed by Cox regression. Rigvir significantly (P<0.05) prolonged survival in substage IB-IIC melanoma patients following surgery compared with patients who were under observation (according to current guidelines). The hazard ratio for patients under observation versus treated with Rigvir was statistically significantly different: hazard ratio 6.27 for all, 4.39 for substage IIA-IIB-IIC and 6.57 for substage IIB-IIC patients. The follow-up period was not statistically different between both treatment groups. These results indicate that the patients treated with Rigvir had a 4.39-6.57-fold lower mortality than those under observation. In this study, there was no untoward side effect or discontinuation of Rigvir treatment. Safety assessment of adverse events graded according to NCI CTCAE did not show any value above grade 2 in Rigvir-treated patients. In conclusion, Rigvir significantly prolongs survival in early-stage melanoma patients without any side effect.

Fig. 1

Cox regression analysis plots of survival of melanoma patients following surgery. P is the statistical significance of the difference between the Rigvir (—) group and the observation according to current guidelines (observation) group (---) after adjustment for age, sex and substage; hazard ratio (HR), 95% confidence interval (CI). (a) Substages IB, IIA, IIB, IIC, Rigvir (N=52), observation (N=27), P<0.005, HR=6.27 (CI: 1.75–22.43). (b) Substages II (A, B, C), Rigvir (N=35), observation (N=22), P<0.032, HR=4.39 (CI: 1.14–16.98). (c) Substages IIB and IIC, Rigvir (N=19), observation (N=17), P<0.014, HR=6.57 (CI: 1.47–29.46).