Generating MHC Class II+/Ii- phenotype after adenoviral delivery of both an expressible gene for MHC Class II inducer and an antisense Ii-RNA construct in tumor cells.

Tumor cells engineered by gene transduction to be MHC Class II+/Ii- are novel APCs capable of presenting endogenous tumor antigen epitopes to activate T helper cells. The MHC Class II+/Ii- tumor cell phenotype is created by transfecting genes for either CIITA or IFN-gamma, and inhibiting induced Ii mRNA by an Ii reverse gene construct (Ii-RGC). Adenoviral vectors are preferred for the delivery of such genes because of high infection efficiency and ubiquity of the adenoviral receptor on many cell types and tumors. Here we show that at 5 MOI (multiplicity of infection), recombinant adenoviruses with CIITA or IFN-gamma genes converted virtually all MC-38 colon adenocarcinoma cells and Renca renal carcinoma cells in culture to MHC Class II+/Ii+ cells. A single recombinant adenovirus with both genes for IFN-gamma and Ii-RGC (rAV/IFN-gamma/Ii-RGC) efficiently induced the MHC Class II+/Ii- phenotype. Injection of tumor nodules with rAV/Ii-RGC and rAV/CIITA/IFN-gamma combined with a suboptimal dose of rAV/IL-2 induced a potent antitumor immune response. The methods are adaptable for producing enhanced genetic vaccines, attenuated virus vaccines (eg, vaccinia), and ex vivo cell-based vaccines (dendritic and tumor cells).

MHC class II allosteric site drugs: new immunotherapeutics for malignant, infectious and autoimmune diseases.

The discovery of the interactions of the 'Ii-Key' segment of the Ii protein with the major histocmpatibility complex (MHC) Class II allosteric site, which is adjacent to the antigenic peptide-binding site, creates therapeutic opportunities by regulating the antigenic peptide binding to MHC class II molecules. The binding of Ii-Key to the MHC class II allosteric site loosens the hold of the MHC Class II 'clamshell' on antigenic peptides and leads to highly efficient antigenic peptide charging to or releasing from the MHC class II antigenic peptide-binding groove. Ii-Key peptide-induced spilling of bound antigenic peptide, or replacement with inert blockers, leads to 'inert immunosuppression'. Highly efficient replacement of ambient with vaccine peptides by Ii-Key permits 'active immunosuppression' for antigen-specific control of autoimmune diseases in the absence of cytokines or adjuvants. On the other hand, active immunization against cancer or infectious disease can result from epitope replacement mediated by Ii-Key and accompanied by cytokines or other adjuvants. Finally, linking the Ii-Key peptide through a simple polymethylene bridge to an antigenic sequence vastly increases the potency of MHC Class II peptide vaccines. In summary, the discovery of the MHC class II allosteric site allows one to increase the efficiency of MHC class II-related, antigenic epitope-specific therapy for malignant, infectious, and autoimmune diseases. The focus of this review is on the mechanism and potential clinical use of such novel allosteric site-directed, Ii-key drugs.

Radioimmunoscintigraphy of pelvic lymph nodes with 111indium-labeled monoclonal antibody CYT-356.

In an attempt to define the possible role of radioimmunoscintigraphy to assess noninvasively the pelvic lymph nodes, we studied 19 patients with prostate cancer. All 19 men underwent conventional radiographic imaging of the pelvis with computerized tomography or magnetic resonance imaging before bilateral pelvic lymph node dissection. In addition, radioimmunological scanning with 111indium-labeled monoclonal antibody CYT-356 was performed. Pathologically 8 of the 19 patients had histological confirmation of metastatic nodal disease ranging from 1 to 15 mm. The monoclonal scan was positive at a site corresponding to the histologically confirmed nodal foci in 4 of the 8 patients. Since each hemipelvis could be independently assessed for pathological disease and imaging status, we report site-specific analysis of the monoclonal antibody scan in 38 hemipelves. The overall accuracy was 76% with a sensitivity and specificity of 44% and 86%, respectively. The negative predictive value was 83% and the positive predictive value was 50%. The administration of a single dose of CYT-356 antibody is safe, feasible and capable of detecting soft tissue nodal disease. A negative scan enables the physician to predict noninvasively a low probability of nodal disease for individuals at high risk. The detection threshold of this antibody scan appears to be disease foci 5 mm. or greater.

Immunoscintigraphy in patients with colorectal, ovarian, and prostate cancer. Results with site-specific immunoconjugates.

Application of monoclonal antibody (MoAb) technology to cancer management is discussed by reviewing the development and clinical evaluation of two MoAb-based immunoscintigraphic agents (111In-satumomab pendetide [OncoScint CR/OV-In] and 111In-CYT-356; Cytogen Corporation, Princeton, NJ). Both agents were prepared using a site-specific MoAb modification method that preserves the immunoreactivity of the radiolabeled immunoconjugate. 111In-satumomab pendetide is an 111In-labeled conjugate of the murine MoAb B72.3, which is directed to TAG-72, an antigen expressed by the majority of adenocarcinomas. By providing information that complements the results of standard radiographic diagnostic modalities, this imaging agent can aid in the treatment of patients with colorectal or ovarian cancer. Immunoscintigraphy with 111In-satumomab pendetide has been shown to assist in medical-surgical management by detecting occult extrahepatic lesions, clarifying equivocal results of other diagnostic imaging tests, and evaluating the extent and resectability of known tumor lesions. 111In-CYT-356 is an 111In-labeled conjugate of the murine MoAb 7E11-C5.3, which is reactive with prostatic carcinoma, benign prostatic hypertrophy, and, to a lesser extent, normal prostatic tissue. Results of preliminary clinical investigations suggest that 111In-CYT-356 immunoscintigraphy can be useful for the presurgical staging of prostatic carcinoma and for the detection of occult distant disease in patients with negative or equivocal results on standard imaging tests. Results with these site-specifically radiolabeled immunconjugates demonstrate the clinical utility of MoAb-based imaging agents in the treatment of patients with solid tumors.