Objectives VIRO-15 phase IB trial (NCT02759588) enrolled 11 patients with PROC, extensive tumor burden, and median 5 prior lines of therapy. We aimed to retrospectively determine factors that predict clinical benefit from VOV monotherapy in PROC.

Methods Patients received a modified VOV (GL-ONC1, Genelux Corp.) intra-peritoneally on two consecutive days. Four patients had apparent clinical benefit with >5 mos progression-free survival (PFS) following virotherapy (A). Seven (B) patients had <5 mo PFS. Comparative analyses included: measures of immune-competence with neutralizing antibody (NA) titers, virus-encoded glucuronidase activity (GA), tumor response by RECIST 1.1, Prognostic Nutritional Index (PNI), circulating tumor cells (CTCs), number of prior platinum and total therapies. Mann-Whitney test, t-test, z-test were used to evaluate differences between the groups.

Results Following GL-ONC1, the PFS was 10.9±5.1 and 2.4±1.1 mos for A vs B (p< 0.05). Mean OS for A was 21.7±8.2 mos vs 3.6±1.5 mos for B (p<0.05). Three A pts are alive, and one with stable disease died at 8-mos from pulmonary embolism. Factors that predicted clinical benefit were: i) PNI [mean 49.0±5.7 vs 42.1±4.3 (p<0.05)], ii) Week-5 CA125 values < Week-2 [4/4 vs 0/7 (p<0.01)], iii) absence of CTC [3/4 vs 1/7 pts (p<0.05)].

Conclusions Factors associated with clinical benefit post GL-ONC1 monotherapy in PROC include higher PNI, absence of CTCs, and Week-5 CA125 less than Week-2 levels. In the absence of these factors, cytotoxic therapy should be considered by Week-6 following GL-ONC1. Three patients are currently alive at 22.8–28.2 mos, following additional therapies.