Systemic administration of recombinant interferon alfa in carcinoma patients upregulates the expression of the carcinoma-associated antigens tumor-associated glycoprotein-72 and carcinoembryonic antigen

Purpose: The ability of interferons (IFNs) to enhance tumor-associated antigen expression may be an important approach to enhance the efficacy of some monoclonal antibody (MAb)-based protocols for tumor diagnosis and/or therapy. The present study was designed to determine whether systemic IFNα- 2a administration (via the intramuscular [IM] route) could upregulate the expression of tumor-associated glycoprotein-72 (TAG-72) and/or carcinoembryonic antigen (CEA) at histologically confirmed sites of carcinoma. Patients and Methods: Eighteen patients diagnosed with gastrointestinal (GI) carcinoma received systemic IFNα-2a according to four dose schedules. In cohorts I and II, patients received two injections of 3 or 6 x 106 U IFNα-2a per injection, respectively. Patients in cohorts III and IV received the same doses of IFNα-2a, 3 and 6 x 106 U, respectively, but three injections were given. Tumor and normal colonic mucosa biopsies were obtained from each patient by endoscopy before IFNα-2a and after IFNα-2a at surgery. The levels of TAG-72 and CEA expression were measured by (I) immunohistochemistry and reported as percent antigen-positive tumor cells, as well as the relative staining intensity, and (2) a quantitative radioimmunoassay. Results: TAG-72 and CEA levels were consistently increased in tumor biopsies taken from patients in cohorts III and IV. For example, of 10 patients treated in cohorts III and IV, eight had enhanced TAG-72 expression when measured either as percentage TAG-72-positive tumor cells or as an increased MAb staining intensity following IFNα-2a. CEA expression in tumor biopsies from seven of 10 patients in cohorts III and IV was also elevated following IFNα-2a treatment. Quantitative analysis of TAG-72 and CEA levels in tumor biopsies confirmed higher tumor antigen levels following IFNα-2a administration. No such increases in TAG-72 or CEA levels were observe in tumor samples taken from patients in cohorts I and II. CEA or TAG- 72 expression in samples of histologically confirmed normal colonic mucosa showed little or no change after IFNα-2a treatment. Conclusion: Systemic IFNα-2a administration can up-regulate TAG-72 and CEA expression at distal tumor sites, which may play an important role in immunodiagnosis and therapy.