Generation of therapeutic immunoconjugates via Residue-Specific Conjugation Technology (RESPECT) utilizing a native cysteine in the light chain framework of Oryctolagus cuniculus.

The conjugation of toxins, dyes, peptides, or proteins to monoclonal antibodies is often performed via free thiol groups generated by either partial reduction methods or engineering free cysteine residues into the antibody sequence. Antibodies from the rabbit Oryctolagus cuniculus have an additional intrachain disulfide bond, whereby the light chain variable kappa domain is bridged to the constant kappa region between cysteine residues at positions 80 and 171, respectively. Chimerization of rabbit antibodies with human constant domains allows for the generation of a free thiol group at the light chain position 80 (C80) that can be used for site-specific conjugation. An efficient process for the purification and simultaneous removal of cysteinylation at the C80 site was developed. The unpaired C80 was shown to be efficiently conjugated using several different maleimido-based ligands. REsidue SPEcific Conjugation Technology (RESPECT) antibody-drug conjugates prepared using rabbit-human chimeric anti-human mesothelin rabbit antibodies and maleimido-PEG2-auristatin conjugated to C80 were shown to be highly potent and specific in vitro and effective in vivo in reduction of tumor growth in a highly aggressive mesothelin-expressing xenograft tumor model.

Modifiable risk factors for non-adherence to immunosuppressants in renal transplant recipients: a cross-sectional study.

BACKGROUND: Non-adherence to immunosuppressants is a major cause of renal transplant failure. Interventions to improve adherence need to target modifiable risk factors. METHODS: Adherence was measured using the 'gold standard' measure of electronic monitoring in 58 adult renal transplant recipients from a UK transplant unit. Subjects were identified from a stratified random sample of 153 recipients recruited to a larger cross-sectional study comparing different measures of adherence. Inclusion criteria included age over 18 years and a functioning renal transplant, transplanted 6-63 months previously. Exclusion criteria included residence outside the region served by the unit and inability to give informed consent. Health beliefs, depression and functional status were measured using standardized questionnaires (Beliefs about Medicines Questionnaire, Illness Perception Questionnaire, Revised Clinical Interview Schedule and SF-36) and semi-structured interview. Transplant and demographic details were collected from the notes. RESULTS: Seven [12%, 95% confidence interval (CI) 4-20%] subjects missed at least 20% of days medication and 15 (26%, 15-37%) missed at least 10% of days. Lower belief in the need for medication and having a transplant from a live donor were the major factors associated with non-adherence. Depression was common, although not strongly associated with non-adherence. CONCLUSIONS: Beliefs about medication are a promising target for interventions designed to improve adherence. The lower adherence in recipients of transplants from live donors needs confirming but may be clinically important in light of the drive to increase live donation.

Frequency and impact of nonadherence to immunosuppressants after renal transplantation: a systematic review.

Nonadherence to immunosuppressants is recognized to occur after renal transplantation, but the size of its impact on transplant survival is not known. A systematic literature search identified 325 studies (in 324 articles) published from 1980 to 2001 reporting the frequency and impact of nonadherence in adult renal transplant recipients. Thirty-six studies meeting the inclusion criteria for further review were grouped into cross-sectional and cohort studies and case series. Meta-analysis was used to estimate the size of the impact of nonadherence on graft failure. Only two studies measured adherence using electronic monitoring, which is currently thought to be the most accurate measure. Cross-sectional studies (n=15) tended to rely on self-report questionnaires, but these were poorly described; a median (interquartile range) of 22% (18%-26%) of recipients were nonadherent. Cohort studies (n=10) indicated that nonadherence contributes substantially to graft loss; a median (interquartile range) of 36% (14%-65%) of graft losses were associated with prior nonadherence. Meta-analysis of these studies showed that the odds of graft failure increased sevenfold (95% confidence interval, 4%-12%) in nonadherent subjects compared with adherent subjects. Standardized methods of assessing adherence in clinical populations need to be developed, and future studies should attempt to identify the level of adherence that increases the risk of graft failure. However, this review shows nonadherence to be common and to have a large impact on transplant survival. Therefore, significant improvements in graft survival could be expected from effective interventions to improve adherence.

Measuring compliance with drug regimens after renal transplantation: comparison of self-report and clinician rating with electronic monitoring.

Nonadherence to immunosuppressants in renal transplant recipients is a major factor affecting graft survival, but it is difficult to detect accurately in clinical practice. Adherence was measured in 153 adult renal transplant recipients using self-report questionnaires and interview, clinician rating, and cyclosporine levels. The sensitivity and specificity of these measures were determined by comparison with electronic monitoring in a randomly selected subsample of 58 subjects. Measures of adherence in current clinical use do not perform well when tested against electronic monitoring. Self-report at a confidential interview was the best measure of adherence for the detection of both missed doses and erratic timing of medication. However, the use of a confidential interview is not directly applicable to a clinical setting. Further research on how best to facilitate disclosure in clinical settings may be the best way to develop adherence measures for use in routine practice.