Oncolytic Adenovirus With Temozolomide Induces Autophagy and Antitumor Immune Responses in Cancer Patients

Abstract

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.

Consensus guidelines for the detection of immunogenic cell death

“…140,142,174 In a vast majority of models, the secretion of ATP by cells exposed to ICD inducers requires an intact autophagic machinery. 83,138,139,175 In these settings, the genetic or pharmacological inhibition of autophagy limits ATP release by cells succumbing to ICD and hence negatively influences their ability to elicit an adaptive immune response upon inoculation in immunocompetent syngeneic mice. 60,138,139 Along similar lines, the chemical inducer of autophagy STF-62247 increases the immunostimulatory potential of ICD as triggered by chlorin-e6-based photodynamic therapy (MK, unpublished observations).…”

Immune Checkpoint Blockade, Immunogenic Chemotherapy or IFN-α Blockade Boost the Local and Abscopal Effects of Oncolytic Virotherapy

“…In the majority of cases, the most effective OV treatments combine potent viral oncolysis with induction of a specific immune response against tumor antigens, as shown in several clinical and preclinical studies (9)(10)(11)(12). The mechanisms how OV therapies elicit antitumor immune responses are not clearly understood yet, but likely involve the capture of released tumor antigens by bystander antigen-presenting cells (APC) following tumor cell lysis (13).…”

Serum HMGB1 is a predictive and prognostic biomarker for oncolytic immunotherapy

“…Altogether 64 patients featured T-cell inductions against the tested tumor-epitope survivin in ELI-SPOT analysis, and 48 of these were coupled with simultaneous unspecific interferon-g inductions, which may represent T-cells reactive to other tumor epitopes. 21,22 While the frequency of T-cell induction was similar in both groups (46.7% in low and 52.2% in high HMGB1 group), only the low-HMGB1 (Fig. 2C).…”

“…First, therapy tolerance was equally well-tolerated in both HMGB1 groups as seen in reported adverse reactions (Table S1), and appeared to be in line with previous reports. 21,22,[26][27][28][29][30][31] Second, virus replication -as estimated by virus genomes in bloodwas assessed without differences between the groups (Fig. S2).…”

“…Thus, our HMGB1 data help interpret antitumor T-cell data, which have previously been confusing as no correlation to treatment outcomes have been seen. 21,22,31 Adding to immune mechanistic observation, only the low-HMGB1 patients showed further benefit from highly immunogenic treatments with GMCSF or CD40-ligand coding viruses. Moreover, high-HMGB1 patients showed a trend for higher levels of pro-inflammatory IL-6 at baseline, which has been linked to advanced disease, immunosuppression, and poor effectiveness of immunotherapy.…”