Enzyme immunoassay for the qualitative determination of specific antibodies to Ipilimumab (Yervoy®) in human serum and plasma. The Assay Genie Antibody to Ipilimumab (Yervoy®) ELISA Kit is intended for the qualitative determination of antibodies to Ipilimumab (Yervoy®) in serum and plasma. It is for professional use only.

The Assay Genie Antibody to ipilimumab (Yervoy®) ELISA is a sandwich assay for the determination of antibodies against ipilimumab in serum and plasma samples. During the first incubation period, antibodies to ipilimumab in patient serum/ plasma samples are captured by the ipilimumab (Yervoy®) coated on the wall of the microtiter wells. After washing away the unbound components from samples, a peroxidase-labelled specific conjugate is added to each well and then incubated. After a second washing step, the bound enzymatic activity is detected by addition of tetramethylbenzidine (TMB) chromogen-substrate. Finally, the reaction is terminated with an acidic stop solution. The intensity of the reaction colour is directly proportional to the concentration of ipilimumab in sample.

Ipilimumab, a recombinant human monoclonal antibody (IgG1 kappa immunoglobin), is an antineoplastic agent. Ipilimumab is a fully human IgG1κ antibody that binds to CTLA-4 (cytotoxic T lymphocyte associated antigen 4), a molecule on T-cells that is indicated for unresectable or metastatic melanoma. The absence or presence of CTLA-4 can augment or suppress the immune system's T-cell response in fighting disease. Ipilimumab is designed to block the activity of CTLA-4, thereby sustaining an active immune response in its attack on cancer cells. The proposed mechanism of action is indirect and may be through T-cell - mediated anti-tumor immune responses.

Ipilimumab is indicated for the treatment of unresectable or metastatic melanoma in adults. It is also used to reduce the risk of the deadly skin cancer returning after surgery. Ipilimumab (Yervoy) shrinks tumors and contributes to patient recovery with advanced melanoma live longer. It is also approved for adjuvant therapy.

In one pharmacokinetic study of patients with unresectable or metastatic melanoma peak concentrations, trough concentrations, and area under the curve (AUC) were found to be dose proportional in the dosage range examined (0.3, 3, or 10mg/kg every 3 weeks for four doses). The metabolism of ipilimumab does not involve the cytochrome P450 enzyme system. Because ipilimumab is a protein it is expected to be degraded into small peptides and amino acids by proteolytic enzymes. Clearance was measured to be 15.3mL/hr-16.8 mL/hr. In one pharmacokinetic study examining ipilimumab administered every 3 weeks, clearance was found to be time invariant.

Minimal systemic accumulation was observed (accumulation index of 1.5-fold or less). Steady state concentrations was reached by the third dose. Clearance will increase with increasing body weight; however, no dose adjustment is needed if administration occurs on a mg/kg basis. The following had no clinically meaningful influence on clearance: Age (range 26-86 years), gender, creatinine clearance, baseline AST, total bilirubin, ALT levels, concomitant use of budesonide, performance status, HLA-A2*0201 status, positive anti-ipilimumab antibody status, prior use of systemic anticancer therapy, baseline lactate dehydrogenase levels.

The pharmacodynamics of Ipilimumab are not completely understood. In melanoma patients receiving Ipilimumab, the mean peripheral blood absolute lymphocyte counts (ALC) increased throughout the induction dosing period. This increase occurred in a dose-dependent fashion in Phase 2 studies. Ipilimumab given with or without gp100 at 3 mg/kg increased ALC throughout the induction dosing period, but no meaningful change in ALC occurred in the control group who received an investigational peptide vaccine alone. Furthermore, ipilimumab binds to CTLA-4 with high affinity (Kd = 5.24 ± 3.62 nM). As a result, ligands CD80 and CD86 are blocked from binding to CTLA-4 with a minimum EC50 value of 0.2 μg/mL.

As with any biologic therapeutic, immunogenicity, in the form of anti-ipilimumab antibodies can occur. The demonstration of anti-ipilimumab antibodies during treatment with ipilimumab is a major concern. The Assay Genie Anti-Ipilimumab ADA Qualitative ELISA Kit can be efficiently used for monitoring anti-ipilimumab antibodies during therapy and offers the clinician a tool for decision on possible preventive measures such as the potential addition of an immunosuppressive drug to reduce anti-ipilimumab antibodies.

YERVOY is a trademark of Bristol-Myers Squibb Company.