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In clinical trials with oncolytic adenoviruses, there has been no mortality associated with treatment vectors. Likewise, in the Advanced Therapy Access Program (ATAP), where 290 patients were treated with 10 different viruses, no vector-related mortality was observed. However, as the patient population who received adenovirus treatments in ATAP represented heavily pretreated patients, often with very advanced disease, some patients died relatively soon after receiving their virus treatment mandating autopsy to investigate cause of death. Eleven such autopsies were performed and confirmed disease progression as the cause of death in each case. The regulatory requirement for investigating the safety of advanced therapy medical products presented a unique opportunity to study tissue samples collected as a routine part of the autopsies. Oncolytic adenoviral DNA was recovered in a wide range of tissues, including injected and noninjected tumors and various normal tissues, demonstrating the ability of the vector to disseminate through the vascular route. Furthermore, we recovered and cultured viable virus from samples of noninjected brain metastases of an intravenously treated patient, confirming that oncolytic adenovirus can reach tumors through the intravascular route. Data presented here give mechanistic insight into mode of action and biodistribution of oncolytic adenoviruses in cancer patients.

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.

Oncolytic adenoviruses and certain chemotherapeutics can induce autophagy and immunogenic cancer cell death. We hypothesized that the combination of oncolytic adenovirus with low-dose temozolomide (TMZ) is safe, effective, and capable of inducing antitumor immune responses. Metronomic low-dose cyclophosphamide (CP) was added to selectively reduce regulatory T-cells. Preclinically, combination therapy inhibited tumor growth, increased autophagy, and triggered immunogenic cell death as indicated by elevated calreticulin, adenosine triphosphate (ATP) release, and nuclear protein high-mobility group box-1 (HMGB1) secretion. A total of 41 combination treatments given to 17 chemotherapy-refractory cancer patients were well tolerated. We observed anti- and proinflammatory cytokine release, evidence of virus replication, and induction of neutralizing antibodies. Tumor cells showed increased autophagy post-treatment. Release of HMGB1 into serum--a possible indicator of immune response--increased in 60% of treatments, and seemed to correlate with tumor-specific T-cell responses, observed in 10/15 cases overall (P = 0.0833). Evidence of antitumor efficacy was seen in 67% of evaluable treatments with a trend for increased survival over matched controls treated with virus only. In summary, the combination of oncolytic adenovirus with low-dose TMZ and metronomic CP increased tumor cell autophagy, elicited antitumor immune responses, and showed promising safety and efficacy.

Augmenting antitumor immunity is a promising way to enhance the potency of oncolytic adenoviral therapy. Granulocyte-macrophage colony-stimulating factor (GMCSF) can mediate antitumor effects by recruiting natural killer cells and by induction of tumor-specific CD8(+) cytotoxic T-lymphocytes. Serotype 5 adenoviruses (Ad5) are commonly used in cancer gene therapy. However, expression of the coxsackie-adenovirus receptor is variable in many advanced tumors and preclinical data have demonstrated an advantage for replacing the Ad5 knob with the Ad3 knob. Here, a 5/3 capsid chimeric and p16-Rb pathway selective oncolytic adenovirus coding for GMCSF was engineered and tested preclinically. A total of 21 patients with advanced solid tumors refractory to standard therapies were then treated intratumorally and intravenously with Ad5/3-D24-GMCSF, which was combined with low-dose metronomic cyclophosphamide to reduce regulatory T cells. No severe adverse events occurred. Analysis of pretreatment samples of malignant pleural effusion and ascites confirmed the efficacy of Ad5/3-D24-GMCSF in transduction and cell killing. Evidence of biological activity of the virus was seen in 13/21 patients and 8/12 showed objective clinical benefit as evaluated by radiology with Response Evaluation Criteria In Solid Tumors (RECIST) criteria. Antiadenoviral and antitumoral immune responses were elicited after treatment. Thus, Ad5/3-D24-GMCSF seems safe in treating cancer patients and promising signs of efficacy were seen.

Oncolytic immunotherapy has taken significant steps towards clinical availability for cancer patients, as the FDA recently approved Imlygic (T-Vec) for the treatment of melanoma. Despite the several oncolytic virus trials, there are no known biomarkers which could predict the treatment outcome of oncolytic virotherapy. Therefore, previous clinical experiences should be utilized as guidance for further treatment optimization and patient selection. The patients analyzed consisted of 246 patients treated with oncolytic adenovirus as a part of the Advanced Therapy Access Program which was ongoing in Helsinki 2007-2012. Taken together with the increasing understanding that immunological factors might determine the efficacy of oncolytic virotherapy, we studied whether neutralizing antibodies and peripheral blood cell counts would have prognostic and/or predictive significance in the context of oncolytic adenovirus treatments. Additionally, tumor burden was assessed both in terms of primary tumor and metastases. We observed presence of neutralizing antibodies before treatment to be correlated with shorter overall survival (p=0.028). Blood cell counts analyses revealed that patients who had high neutrophil to lymphocyte ratio at baseline had significantly shorter overall survival (p

Breast cancer is a heterogeneous disease, characterized by several distinct biological subtypes associated with specifical biological behavior and different clinical outcomes. Triple-negative breast cancer (TNBC) is defined as estrogen receptor (ER)-negative, progesterone receptor (PR)-negative and lacking overexpression of human epidermal growth factor receptor 2 (HER2). Among all the breast cancer subtypes, TNBC (10-15% of breast cancers) is associated with a worse prognosis.Oncolytic virus replication is an immunogenic phenomenon, and viruses can be armed with immunostimulatory molecules. Cyclophosphamide (CP) is a chemotherapy drug that works by slowing or stopping cell growth. At higher doses, CP is associated with increased cytotoxicity and immunosuppression, while at low continuous dosage it shows immunostimulatory and antiangiogenic properties. Therefore, the combination of oncolytic immunovirotherapy with low-dose CP is an appealing approach.We investigated the potency of oncolytic adenovirus Ad5/3-D24-GMCSF on a TNBC cell line and animal models, in combination with low-dose CP or its main active metabolite 4-hydroxycyclophosphamide (4-HP-CP). Furthermore, we summarized the breast cancer-specific human data from the Advanced Therapy Access Program (ATAP).Low-dose CP effectively increased the efficacy of Ad5/3-D24-GMCSF in vitro and in a TNBC xenograft mouse model. In ATAP, treatments appeared safe and well-tolerated. Fourteen out of sixteen breast cancer patients treated were evaluable for possible therapy benefit with modified RECIST criteria: one patient had minor response, four had stable disease, and nine had progressive disease. One patient was alive at 941 days after treatment.Ad5/3-D24-GMCSF in combination with low-dose CP showed promising efficacy in preclinical studies and possible antitumor activity in breast cancer patients refractory to other forms of therapy. This preliminary data supports continuing the clinical development of oncolytic adenoviruses for treatment of breast cancer, including TNBC.