First generation, E1-deleted Adenovirus subtype 5 (Ad5)-based vectors, although promising platforms for use as cancer vaccines, are impeded in activity by naturally occurring or induced Ad-specific neutralizing antibodies. Ad5-based vectors with deletions of the E1 and the E2b regions (Ad5 [E1-, E2b-]), the latter encoding the DNA polymerase and the pre-terminal protein, by virtue of diminished late phase viral protein expression, were hypothesized to avoid immunological clearance and induce more potent immune responses against the encoded tumor antigen transgene in Ad-immune hosts. Indeed, multiple homologous immunizations with Ad5 [E1-, E2b-]-CEA(6D), encoding the tumor antigen CEA, induced CEA-specific cell-mediated immune (CMI) responses with antitumor activity in mice despite the presence of pre-existing or induced Ad5-neutralizing antibody. In the present phase I/II study, cohorts of patients with advanced colorectal cancer were immunized with escalating doses of Ad5 [E1-, E2b-]-CEA(6D). CEA-specific CMI responses were observed despite the presence of pre-existing Ad5 immunity in a majority (61.3%) of patients. Importantly, there was minimal toxicity, and overall patient survival (48% at 12 months) was similar regardless of pre-existing Ad5 neutralizing antibody titers. The results demonstrate that, in cancer patients, the novel Ad5 [E1-, E2b-] gene delivery platform generates significant CMI responses to the tumor antigen CEA in the setting of both naturally acquired and immunization-induced Ad5-specific immunity.

Adenovirus serotype 5 (Ad5) has been widely used in clinical trials because it expresses inserted transgenes robustly and augments the innate immune response. Strategies to improve Ad5 vectors that can circumvent Ad5 immunity have become a critical issue, especially for use as a cancer immunotherapeutic in which repeated immunization is required. In this study, we constructed a novel Ad5 vector with unique deletions of the viral DNA polymerase and the pre-terminal protein region (Ad5 [E1-, E2b-]). This vector contains the carcinoembryonic antigen (CEA) gene insert and is designed to induce cell-mediated immunity (CMI) against the tumor-associated target. The CEA immunogenicity and in vivo anti-tumor effects of repeated immunizations with Ad5 [E1-, E2b-]-CEA compared with those observed with current generation Ad5 [E1-]-CEA were tested in Ad5 pre-immunized mice. We report that Ad5-immune mice immunized multiple times with Ad5 [E1-, E2b-]-CEA induced CEA-specific CMI responses that were significantly increased over those detected in Ad5-immune mice immunized multiple times with a current generation Ad5 [E1-]-CEA. Ad5 immune mice bearing CEA-expressing tumors that were treated with Ad5 [E1-, E2b-]-CEA had increased anti-tumor response as compared with Ad5 [E1-]-CEA treated mice. These results demonstrate that Ad5 [E1-, E2b-]-CEA can induce CMI immune responses which result in tumor growth inhibition despite the presence of pre-existing Ad5 immunity. Multiple re-immunizations using the same vector platform are now possible with the novel Ad5 [E1-, E2b-] platform.

Background. Chemotherapy‐associated thrombotic thrombocytopenic purpura/hemolytic uremic syndrome (C‐TTP/HUS) is a condition involving thrombocytopenia, microangiopathic hemolytic anemia, and progressive renal dysfunction that develops in 2–10% of patients with a history of malignant neoplasms treated with certain chemotherapeutic agents. Pathogenesis of the disease may depend on the following: (1) generation of endothelial lesions in the kidney microvasculature, resulting from drug toxic effects and/or generation of small soluble circulating immune complexes (CIC), and (2) generation of autoantibodies and/or CIC that trigger aggregation and deposition of platelets around the lesions. Methods. Extracorporeal immunoadsorption treatment of plasma (PROSORBA columns, IMRÉ Corporation, Seattle, WA) to remove immunoglobulin G and CIC was evaluated in 55 patients for the potential to induce significant clinical benefits (increase in platelet count, decrease in hemolysis, stabilization of renal function) and longer survival. Results. Response to therapy was achieved in 25 of 55 patients examined. Response was associated with an estimated 1‐year survival rate of 61%, as compared with an estimated survival rate of only 22% in those who did not respond (P = 0.0001). Patients whose malignant neoplasms were in complete or partial remission at the time of development of C‐TTP/HUS had a significantly higher estimated 1‐year survival rate (74%) as compared with a historic control group of patients receiving other treatments (22%, P = 0.0161). Clinical responses were correlated with normalization of serum levels of CIC and complement components C3c and C4. There were no side effects associated with 75% of treatments. Immunoadsorption therapy was associated with generally mild to moderate manageable side effects, such as fever, chills, nausea/vomiting, respiratory symptoms, pain, hypertension, and hypotension, which were reported in 25% of procedures. Conclusions. This multicenter study establishes protein A immunoadsorption as an effective and safe treatment for cancer chemotherapy‐associated TTP/HUS, an otherwise fatal disease.