Mouse Anti-vc-PAB-MMAE monoclonal antibody, clone C22G22

Purpose Because of the observed success of phase I/II trials, the novel anti-CD30 agent brentuximab vedotin is now being evaluated as a frontline agent in the high-risk pediatric Hodgkin lymphoma trial HLHR13. The objectives of this study were to evaluate the pharmacokinetic variability during weekly dosing of 1.2 mg/kg of brentuximab vedotin, determine factors that may explain this variability, compare our drug exposure with published data, and evaluate toxicity of brentuximab vedotin in the pediatric population. Methods Brentuximab vedotin, MMAE and anti-therapeutic antibody levels were measured in the serum samples of 16 pediatric patients with Hodgkin lymphoma. A compartmental pharmacokinetic model was fit to the data by using nonlinear mixed-effects modeling. Results Clearance and volume of brentuximab vedotin were significantly correlated with weight (p < .001), which was responsible for over 60% of the parameters inter-individual variability. Clearance and volume were higher in boys compared to girls (p = 0.08 and p = 0.03, respectively). Brentuximab vedotin's AUC and C-max were lower in our pediatric study than those reported in adult studies (25 and 11%, respectively). Toxicity was comparable to that of the standard-of-care backbone using vincristine instead of brentuximab vedotin. The sera of all 16 patients remained negative for anti-therapeutic antibodies during and at the end of therapy. Conclusions As in previous studies, weight continues to be the most significant factor explaining brentuximab vedotin's pharmacokinetic variability in pediatric patients. Exposure to weekly dosing appears to be safe and tolerable in pediatric patients.

Targeted therapy is a new type of cancer treatment that most often uses biologically active drugs attached to a monoclonal antibody. This so called antibody-drug conjugate strategy allows the use of highly toxic substances that target tumor cells specifically, leaving healthy tissues largely unaffected. Over the last few years, antibody-drug conjugates have become a powerful tool in cancer treatment. We developed and characterized a novel cytotoxic conjugate against HER2(+) tumors in which the antibody has been substituted with a much smaller molecule: the affibody. The conjugate is composed of the Z(HER2:2891) affibody that recognizes HER2 and a highly potent cytotoxic drug auristatin E. The Z(HER2:2891) molecule does not contain cysteine(s) in its amino acid sequence. We generated 3 variants of Z(HER2:2891), each containing a single cysteine to allow conjugation through the maleimide group that is present in the cytotoxic component. In 2 variants, we introduced single S46C and D53C substitutions. In the third variant, a short Drug Conjugation Sequence (DCS) containing a single cysteine was introduced at the C-terminus of Z(HER2:2891), resulting in Z(HER2:2891)-DCS. The latter variant exhibited a significantly higher conjugation yield, and therefore its cytotoxicity has been studied more thoroughly. The Z(HER2:2891)-DCS-MMAE conjugate killed the HER2-overexpressing SK-BR-3 and MDA-MB-453 cells efficiently (IC50 values of 5.2 and 24.8 nM, respectively). The T-47-D and MDA-MB-231 cells that express normal levels of HER2 were significantly less sensitive to the conjugate (IC50 values of 135.6 and 161.5 nM, respectively). Overall, we have demonstrated for the first time that proteins other than antibodies/antibody fragments can be successfully combined with a linker-drug module, resulting in conjugates that eliminate cancer cells selectively.