Safety of glucocorticoids in cancer patients treated with oncolytic adenoviruses

Case-control estimation of the impact of oncolytic adenovirus on the survival of patients with refractory solid tumors

Oncolytic immunotherapy with cytokine armed replication competent viruses is an emerging approach in cancer treatment. In a recent randomized trial, an increase in response rate was seen but the effect on overall survival is not known with any virus. To facilitate randomized trials, we performed a case-control study assessing the survival of 270 patients treated in an Advanced Therapy Access Program (ATAP), in comparison to matched concurrent controls from the same hospital. The overall survival of all virus treated patients was not increased over controls. However, when analysis was restricted to GMCSF-sensitive tumor types treated with GMSCF-coding viruses, a significant improvement in median survival was present (from 170 to 208 days, P = 0.0012, N = 148). An even larger difference was seen when analysis was restricted to good performance score patients (193 versus 292 days, P = 0.034, N = 90). The survival of ovarian cancer patients was especially promising as median survival nearly quadrupled (P = 0.0003, N = 37). These preliminary data lend support to initiation of randomized clinical trials with GMCSF-coding oncolytic adenoviruses.

[(18)F]-fluorodeoxyglucose positron emission tomography and computed tomography in response evaluation of oncolytic adenovirus treatments of patients with advanced cancer

Computed tomography (CT) is the most commonly used radiological response evaluation method in contemporary oncology. However, it may not be optimally suitable for assessment of oncolytic virus treatments because of paradoxical inflammatory tumor swellings, which result from virus treatments, particularly when viruses are armed with immunostimulatory molecules. Here we investigated the prognostic utility of CT and [(18)F]-fluorodeoxyglucose (FDG) positron emission tomography (PET) in oncolytic virus treatments. We also investigated possible appearance of false-positive FDG signals in FDG-PET imaging of humans and hamsters treated with oncolytic adenoviruses. First, immunocompetent Syrian hamsters were treated with intratumoral adenovirus injections, tumor growth was followed up, and [(18)F]-FDG-uptake was quantitated with small animal PET/CT. Second, we describe a retrospective patient series, essentially 17 individual case reports, of advanced cancer patients treated with oncolytic adenoviruses in the context of an Advanced Therapy Access Program (ATAP) who underwent radiological response evaluation with both contrast-enhanced CT and FDG-PET. Third, we collected a retrospective case series of radiological response and survival data of 182 patients treated with oncolytic adenoviruses in ATAP to evaluate the prognostic reliability of CT and FDG-PET. Overall, responses in CT and FDG-PET correlated well with each other and were equally reliable as prognostic markers for long survival after oncolytic adenovirus treatment. Interestingly, we observed that new FDG-avid lymph nodes appearing in FDG-PET after virus treatments may represent inflammatory responses and therefore should not be interpreted as treatment failure in the absence of other signs or verification of disease progression. We also observed indications that FDG-PET might be more sensitive in detection of responses than tumor size.

An oncolytic adenovirus enhanced for toll-like receptor 9 stimulation increases antitumor immune responses and tumor clearance

Oncolytic viruses represent a multifaceted tool for cancer treatment. In addition to specific killing of cancer cells (oncolysis), these agents also provide danger signals prompting the immune system to stimulate an antitumor immune response. To increase adenovirus adjuvancy, we engineered the genome of Ad5D24 by inserting 18 immunostimulatory islands (Ad5D24-CpG). The toxicity and immunogenicity profile of Ad5D24-CpG showed that the safety of the maternal virus was retained. The efficacy of the CpG-enriched virus was assessed in a xenograft model of lung cancer where a significant increase in antitumor effect was seen in comparison with controls. When the experiment was repeated in animal depleted of natural killer (NK) cells, Ad5D24-CpG lost its advantage. The same was seen when Toll-like receptor (TLR)9 was blocked systemically. In a syngeneic model of melanoma (B16-OVA), we observed a significant increase of OVA-specific T cells and a decrease of activation of myeloid-derived suppressor cells in Ad5D24-CpG-treated mice. In conclusion, we have generated the first genetically modified oncolytic adenovirus backbone able to enhance TLR9-stimulation for increased antitumor activity.