Abstract
Pembrolizumab is a humanized immunoglobulin G4-kappa anti-PD1 antibody used in the treatment of different solid tumors or haematological malignancies. A liquid chromatography coupled with a high resolution mass spectrometry (orbitrap technology) method was fully developed, optimized, and validated for quantitative analysis of pembrolizumab in human plasma. A mass spectrometry assay was used for the first time a full-length stable isotope-labelled pembrolizumab-like (Arginine 13C6-15N4 and Lysine 13C6-15N2) as an internal standard; the sample preparation was based on albumin depletion and trypsin digestion and, finally, one surrogate peptide was quantified in positive mode. The assay showed good linearity over the range of 1–100 μg/mL, a limit of quantification at 1 μg/mL, excellent accuracy from 4.4% to 5.1%, and also a between-day precision below 20% at the limit of quantification. In parallel, an in-house ELISA was developed with a linearity range from 2.5 to 50 µg/mL. Then, results were obtained from 70 plasma samples of cancer patients that were treated with pembrolizumab and quantified with both methods were compared using the Passing-Bablok regression analysis and Bland-Altman plotting. The LC-MS/HRMS method is easy to implement in the laboratory for use in the context of PK/PD studies, clinical trials, or therapeutic drug monitoring.
Highlights
Cancer treatments are based on different strategies generally combining several approaches such as chemotherapy, surgery, and radiotherapy
We described a quick, easy implementation in routine practice and reliable quantification method of PBZ in human plasma with liquid chromatography coupled with a high-resolution-mass-spectrometry (LC-MS/HRMS)
Proteotypic peptides are usually localized on the complementary determining region (CDR), which contains amino acids interacting with their target, as PD1 for PBZ [22,23]
Summary
Cancer treatments are based on different strategies generally combining several approaches such as chemotherapy, surgery, and radiotherapy. Immunotherapy with immune checkpoint inhibitors (ICI) is a new class of drugs, which emerged ten years ago with. The ICIs essentially take the ‘brakes’ off the immune system, which helps it recognize and attack cancer cells. PD-1 blocking therapies such as nivolumab and pembrolizumab (PBZ) showed clinical benefits in different cancer treatments [2,3]. PBZ is a humanized IgG4 anti-PD1 used in the treatment of various solid tumors such as lung cancer, melanoma, head, urothelial carcinoma, neck squamous cancer, and some haematological malignancies [4]. PBZ presents a long-term half-life of 27.3 days [5], and the dose approved is not based on body weight but corresponds to a flat dose of 200 or 400 mg administered every 3 or even
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