RNA as a tumor vaccine: a review of the literature.

Many approaches have been attempted to harness the host immune system to act against malignant tumors. These have included animal and clinical trials with agents to non-specifically boost immunity, factors to augment specific immunity, transfer of lymphokine-activated killer cells and transfer of expanded populations of tumor-infiltrating lymphocytes. Therapeutic vaccination strategies have been employed using tumor extracts, purified tumor antigens, recombinant peptide tumor antigens and specific DNA sequences coding for a tumor antigen (genetic vaccination) both through direct administration to the host and by administration of antigen presenting cells exposed to these materials ex vivo. Recently, the use of RNA has been proposed for use in tumor vaccination protocols. The use of RNA has several potential advantages. Since total cellular RNA or mRNA can be utilized, it is not necessary to know the molecular nature of the putative tumor antigen(s). RNA can be effectively amplified; thus, unlike tumor-extract vaccines, only a small amount of tumor is needed to prepare the material for vaccination. Also, unlike DNA-based vaccines, there is little danger of incorporation of RNA sequences into the host genome. The possible utility of RNA-based vaccines for tumor immunotherapy should be further explored to determine whether such approaches are clinically useful.

Direct health care costs for treatment of diabetes mellitus and hypertension in an IPA-group-model HMO.

The differences in direct health care costs and use between HMO enrollees with both diabetes mellitus and hypertension and enrollees with either disease alone were studied. Two years' worth of medical and pharmacy claims data from a hybrid (independent practice association and group)-model HMO were evaluated. Diagnoses were determined from medical claims data and cross-referenced with prescription information from pharmacy claims data. Aggregate costs associated with each disease, including pharmacy costs, costs of physician office visits, and laboratory costs, were compiled. Comparisons were made of all costs (any cost incurred by the health plan for the member, regardless of disease) and disease-specific costs. The frequency of comorbid conditions was identified. A total of 6195 patients (670 with diabetes and hypertension, 1756 with diabetes alone, and 3769 with hypertension alone) were assessed. Patients with both diseases incurred much higher costs per year than patients with diabetes or hypertension alone (mean costs, $13,446, $8,493, and $8,424, respectively). Hospitalization costs contributed the greatest amount to total costs, while emergency room costs contributed the least. Disease-specific costs for diabetes and hypertension represented less than one quarter of total health care costs per patient. Average disease-specific costs were highest for patients with both diseases ($2,955), followed by costs for patients with hypertension alone ($1,803) and patients with diabetes alone ($689). The percentage spent on prescriptions was much higher for disease-specific costs than for total costs. The three most common comorbid conditions were dyslipidemia, coronary artery disease, and chronic obstructive pulmonary disease, with the frequency of cerebrovascular disease and myocardial infarction more than double in patients with diabetes and hypertension compared with patients with either disease alone. The cost of care for a patient with both diabetes and hypertension, although not double that for a patient with diabetes or hypertension alone, was higher than the cost of treating either disease.