Prevalence of natural and acquired antibodies to amustaline/glutathione pathogen reduced red blood cells.

BACKGROUND: The INTERCEPT™ Blood System for Red Blood Cells (RBCs) utilizes amustaline (S-303) and glutathione (GSH) to inactivate pathogens and leukocytes in transfused RBCs. Treatment-emergent low titer non-hemolytic antibodies to amustaline/GSH RBC were detected in clinical trials using a prior version of the process. The amustaline/GSH process was re-formulated to decrease S-303 RBC adduct formation. STUDY DESIGN AND METHODS: A standard three-cell antibody screening panel was modified to include reagent red cells (RRC) with high (S-303H) or low (S-303L) S-303 adduct density as assessed by flow cytometry, representative of the original and current amustaline/GSH treatment processes, respectively. General hospital and RBC transfusion-dependent patients never exposed, and clinical trial subjects exposed to amustaline/GSH RBC were screened for antibodies to amustaline/GSH RBC using a standardized agglutination assay. RESULTS: Twelve (0.1%) of 10,721 general hospital and 5 (0.5%) of 998 repeatedly-transfused patients not previously exposed to amustaline/GSH RBCs expressed natural, low titer (2-32) IgM and/or IgG (non-IgG1 or IgG3 isotype) antibodies with acridine (a structural element of amustaline) (n = 14) or non-acridine (n = 3) specificity. 11 of 17 sera reacted with S-303L panel RRCs. In clinical studies 81 thalassemia and 25 cardiac surgery patients were transfused with a total of 1085 amustaline/GSH RBCs and no natural or treatment-emergent S-303 antibodies were detected. CONCLUSION: Standardized RRC screening panels are sensitive for the detection of natural and acquired S-303-specific antibodies. Natural low titer antibodies to amustaline/GSH RBC are present in 0.15% of naïve patients. The clinical relevance of these antibodies appears minimal but is under further investigation.

Bendamustine-induced immune hemolytic anemia in a chronic lymphocytic leukemia patient: A case report and review of the literature.

Bendamustine is an alkylating agent approved for the treatment of chronic lymphocytic leukemia (CLL) and B-cell non-Hodgkin lymphoma. There are scant reports on bendamustine-induced immune hemolytic anemia occurring mainly in CLL patients. We report a case of immune hemolytic anemia that developed after exposure to bendamustine in a 70-year-old female with CLL who was previously exposed to fludarabine. Previous exposure to fludarabine is a common finding in the majority of reported cases of bendamustine drug-induced immune hemolytic anemia (DIIHA), including our case. Bendamustine should be suspected as the cause of any hemolytic anemia that develops while on this drug, especially in CLL patients treated previously with fludarabine.

Therapeutic efficacy and safety of red blood cells treated with a chemical process (S-303) for pathogen inactivation: a Phase III clinical trial in cardiac surgery patients.

BACKGROUND: A randomized, double-blind trial is reported of the clinical efficacy of red blood cells (RBCs) treated for pathogen inactivation with S-303, a synthetic labile alkylating agent. STUDY DESIGN AND METHODS: Patients undergoing complex cardiac surgeries were randomly assigned to receive either S-303-treated (test) or conventional (control) RBC transfusion during surgery and for 6 days thereafter. Efficacy was evaluated by comparing the occurrence of a composite primary endpoint of treatment-related morbidity (myocardial infarction and renal failure) and mortality. RESULTS: Two-hundred twenty-three patients were randomly assigned and 148 patients who received transfusions (74 with S-303-treated RBCs and 74 with control RBCs) were evaluable. The incidence of the primary endpoint was equivalent between the two groups (22 and 21% in the S-303-treated and control RBC groups, respectively). Secondary endpoints, including hemoglobin increment (mean, 1.4 vs. 1.5 g/dL), number of RBC transfusions (mean, 4.4 vs. 3.8 units), and other blood product support, were also comparable. The adverse event profile was similar between groups; however, patients who received S-303 RBCs were significantly more likely to develop constipation and less likely to suffer supraventricular extrasystoles. Four patients (2 test and 2 control) demonstrated positive indirect antiglobulin tests with reactivity for S-303 RBCs at one or more time points before or after transfusion, without evidence of hemolysis. CONCLUSION: S-303-treated and conventional RBCs were equivalent with respect to clinical efficacy and safety in supporting the transfusion needs of cardiac surgery patients. Investigations are under way to ascertain the significance of S-303 RBC antibodies and to prevent their occurrence.

Measurement of the critical DNA lesions produced by antibody-directed enzyme prodrug therapy (ADEPT) in vitro, in vivo and in clinical material.

An antibody-directed enzyme prodrug therapy (ADEPT) system against CEA-positive tumours is currently in phase I clinical trials. It consists of a prodrug, 4-[N,N-bis(2-iodoethyl) amino] phenoxycarbonyl L -glutamic acid (ZD2767P) and a conjugate of the F(ab')(2) anti-CEA antibody A5B7 and the bacterial enzyme carboxypeptidase G2 (CPG2). ZD2767P is converted by antibody-targeted CPG2 into an active bifunctional alkylating drug (ZD2767) at the tumour site. The IC(50) value of the prodrug against the human colorectal tumour LS174T cell line was 55 +/- 9 microM following a 1 h exposure. In contrast, co-incubation of ZD2767P with CPG2 resulted in 229-fold increase in activity. Using a modified comet assay, DNA interstrand cross links (ISC) were detected within 1 h of ZD2767P + CPG2 treatment and were repaired by 24 h. A clear dose-response was seen between the level of ISC, growth inhibition and ZD2767 concentration. Administration of a therapeutic dose of ZD2767P 72 h after the F(ab')(2) A5B7 conjugate to mice bearing LS147T xenografts resulted in extensive ISC in the tumour after 1 h; repair was seen at 24 h. Tumour biopsies and peripheral lymphocytes were studied in 5 patients on the ADEPT phase I clinical trial. In 4 patients no ISC were detected. These patients also demonstrated poor localization of conjugate and no tumour response was seen. However a significant level of ISC was detected in one tumour biopsy, which also showed evidence of conjugate localization and clinical response. These studies demonstrate the application of the comet assay in the measurement of ISC in vitro and in clinical material and confirm that activation of ZD2767P results in the formation of DNA crosslinks.

Immunopharmacological studies of PTT.119, a new synthetic bis-(2-chloroethyl)amino-L-phenylalanine derivative.

The new synthetic tripeptide p-F-Phe-m-bis-(2-chloro-ethyl)amino-Phe-Met-etoxy HCl, PTT.119, was studied for its effects on the host immune system. Doses of PTT.119 ranging from 3 to 18 mg/kg were administered i.p. to recipient mice which, at different times after drug treatment, were tested for allograft response, competence in producing lymphocytes active in lethal graft-versus-host disease, delayed-type hypersensitivity, mitogen responsiveness, humoral antibody production and natural resistance against microbial infections. At therapeutically active dosages, PTT.119 appeared to selectively inhibit functions mediated by B lymphocytes, leaving the majority of those involving T-cell subsets largely unaffected, even at the highest doses employed. Moreover, drug treatment had also a limited impact on the in vivo resistance of mice to microbial infection, which was only affected by a drug injection of 18 mg/kg, a dose well within the confidence limits of the mean lethal dose of the drug.

[Immunodepressive properties of antineoplastic agents]. / Immunodepressivnye svoistva nekotorykh protivoopukholevykh preparatov.

Experiments on CBA mice immunized with sheep red blood cells have shown that paphencyl, promycil, prospidin and imidazole-4-carboxamide decrease the number of IgM-antibody-forming cells in mouse spleens during the primary immune response. The highest immunodepressant effect was exhibited by paphencyl, while the least by prospidin. The maximum inhibition of the immune response was observed on paphencyl and promycil administration 24 hours after the immunization, that on prospidin administration 24 hours prior to antigen exposure, and that on imidazole-4-carboxamide administration 24 hours prior and 48 hours after the antigenic stimulation. The degree of antibody genesis suppression depends on the dose of paphencyl, promycil and prospidin and does not depend on the dose of imidazole-4-carboxamide. Paphencyl significantly diminishes the number of hemopoietic stem cells in mouse spleens, while prospidin was less active in this respect.