The Nitrogen Mustards

The nitrogen mustards are powerful cytotoxic and lymphoablative agents and have been used for more than 60 years. They are employed in the treatment of cancers, sarcomas, and hematologic malignancies. Cyclophosphamide, the most versatile of the nitrogen mustards, also has a place in stem cell transplantation and the therapy of autoimmune diseases. Adverse effects caused by the nitrogen mustards on the central nervous system, kidney, heart, bladder, and gonads remain important issues. Advances in analytical techniques have facilitated the investigation of the pharmacokinetics of the nitrogen mustards, especially the oxazaphosphorines, which are prodrugs requiring metabolic activation. Enzymes involved in the metabolism of cyclophosphamide and ifosfamide are very polymorphic, but a greater understanding of the pharmacogenomic influences on their activity has not yet translated into a personalized medicine approach. In addition to damaging DNA, the nitrogen mustards can act through other mechanisms, such as antiangiogenesis and immunomodulation. The immunomodulatory properties of cyclophosphamide are an area of current exploration. In particular, cyclophosphamide decreases the number and activity of regulatory T cells, and the interaction between cyclophosphamide and the intestinal microbiome is now recognized as an important factor. New derivatives of the nitrogen mustards continue to be assessed. Oxazaphosphorine analogs have been synthesized in attempts to both improve efficacy and reduce toxicity, with varying degrees of success. Combinations of the nitrogen mustards with monoclonal antibodies and small-molecule targeted agents are being evaluated. SIGNIFICANCE STATEMENT: The nitrogen mustards are important, well-established therapeutic agents that are used to treat a variety of diseases. Their role is continuing to evolve.

HPLC methods for quantifying anticancer drugs in human samples: A systematic review

Pharmacokinetic (PK) study of anticancer drugs in cancer patients is highly crucial for dose selection and dosing intervals in clinical applications. Once an anticancer drug is administered, it undergoes various metabolic pathways; to determine these pathways, it is necessary to follow the administered drug in biological samples via different analytical methods. In addition, multi-drug quantification methods in patients undergoing multi-drug regimens of cancer therapy can have several benefits, such as reduced sampling time and analysis costs. In order to collect and categorize these studies, we conducted a systematic review of HPLC methods reported for the analysis of anticancer drugs in biological samples. A systematic search was performed on PubMed Medline, Scopus, and Web of Science databases, and 116 studies were included. In summary of included studies, when the objective of a method was to quantify a single drug, MS, or UV detectors were utilized equivalently. On the other hand, in methods with the aim of quantifying drug and metabolite(s) in a single run, MS detectors were the most utilized. This review can provide a comprehensive insight for researchers prior to developing a quantification method and selecting a detector.

A review of bioanalytical methods for chronic lymphocytic leukemia drugs and metabolites in biological matrices

Quantitation of drugs used for the treatment of chronic lymphocytic leukemia in various biological matrices during both pre-clinical and clinical developments is very important, often in routine therapeutic drug monitoring. The first developed methods for quantitation were traditionally done on LC in combination with either UV or fluorescence detection. However, the emergence of LC with mass spectrometry in tandem in early 1990s has revolutionized the quantitation as it has provided better sensitivity and selectivity within a shorter run time; therefore it has become the choice of method for the analysis of various drugs. In this article, an overview of various bioanalytical methods (HPLC or LC-MS/MS) for the quantification of drugs for the treatment of chronic lymphocytic leukemia, along with applicability of these methods, is given.

A sensitive and rapid ultra high-performance liquid chromatography with tandem mass spectrometric assay for the simultaneous quantitation of cyclophosphamide and the 4-hydroxycyclophosphamide metabolite in human plasma

Analysis of cyclophosphamide (CP) and its metabolite, 4-hydroxycyclophosphamide (4OHCP), in a single assay has the ability to improve sampling techniques benefitting both the patients who are receiving the drug and the clinicians drawing samples. Due to instability in plasma (t_1/2 = 4 min), immediate stabilization of 4OHCP with phenylhydrazine is necessary upon sample draw. After stabilization, 4OHCP and the stable CP prodrug concentrations can be analytically measured to elucidate the pharmacokinetics, including half-life and exposure parameters (Cmax and AUC). For this purpose, a sensitive analytical method was developed to measure both the prodrug and active metabolite. A liquid-liquid extraction recovered the analytes prior to analysis with an ultra HPLC-MS/MS. A Thermo Scientific™ Hypersil™ BDS C18, 2.1 × 100 mm, 3.0 μm column was used for compound separation. Mass transitions for CP (m/z 261.0 ➔ 140.0), the internal standard d4-CP (m/z 265.0 ➔ 140.0), 4OHCP (m/z 367.3 ➔ 147.1), and the internal standard AZD7451 (m/z 383.4 ➔ 341.1) were monitored over a calibration range of 34.24-34,240 ng/mL and 3.424-3424 ng/mL for CP and 4OHCP, respectively. Each calibration range proved accurate (<15% deviation) and precise (<15% RSD) for the desired compound. Using this method, CP and 4OHCP plasma levels can be measured in clinical samples from patients receiving this therapy.

Antineoplastic drugs and their analysis: a state of the art review

We provide an overview of the analytical methods available for the quantification of antineoplastic drugs in pharmaceutical formulations, biological and environmental samples.

Genetic markers in CYP2C19 and CYP2B6 for prediction of cyclophosphamide's 4-hydroxylation, efficacy and side effects in Chinese patients with systemic lupus erythematosus

AIMS

The aim of the study was to investigate the combined impact of genetic polymorphisms in key pharmacokinetic genes on plasma concentrations and clinical outcomes of cyclophosphamide (CPA) in Chinese patients with systemic lupus erythematosus (SLE).

METHODS

One hundred and eighty nine Chinese SLE patients treated with CPA induction therapy (200 mg, every other day) were recruited and adverse reactions were recorded. After 4 weeks induction therapy, 128 lupus nephritis (LN) patients continued to CPA maintenance therapy (200-600 mg week(-1)) for 6 months, and their clinical outcomes were recorded. Blood samples were collected for CYP2C19, CYP2B6, GST and PXR polymorphism analysis, as well as CPA and its active metabolite (4-hydroxycyclophosphamide (4-OH-CPA)) plasma concentration determination.

RESULTS

Multiple linear regression analysis revealed that CYP2B6 -750 T > C (P < 0.001), -2320 T > C (P < 0.001), 15582C > T (P = 0.017), CYP2C19*2 (P < 0.001) and PXR 66034 T > C (P = 0.028) accounted for 47% of the variation in 4-OH-CPA plasma concentration. Among these variants, CYP2B6 -750 T > C and CYP2C19*2 were selected as the combination genetic marker because these two SNPs contributed the most to the inter-individual variability in 4-OH-CPA concentration, accounting for 23.6% and 21.5% of the variation, respectively. Extensive metabolizers (EMs) (CYP2B6 -750TT, CYP2C19*1*1) had significantly higher median 4-OH-CPA plasma concentrations (34.8, 11.0 and 6.6 ng ml(-1) for EMs, intermediate metabolizers (IMs) and poor metabolizers (PMs), P < 0.0001), higher risks of leukocytopenia (OR = 7.538, 95% CI 2.951, 19.256, P < 0.0001) and gastrointestinal toxicity (OR = 7.579, 95% CI 2.934, 19.578, P < 0.0001), as well as shorter median time to achieve complete remission (13.2, 18.3 and 23.3 weeks for EMs, IMs and PMs, respectively, P = 0.026) in LN patients than PMs (CYP2B6 -750CC, CYP2C19*2*2) and IMs.

CONCLUSIONS

Our findings have indicated that genetic markers of drug metabolizing enzymes could predict the 4-hydroxylation, adverse reactions and clinical efficacy of CPA. This is a necessary first step towards building clinical tools that will help assess clinical benefit and risk before undergoing CPA treatment in Chinese SLE patients.

Pharmacogenomics and personalized medicine: a review focused on their application in the Chinese population

The field of pharmacogenomics was initiated in the 1950s and began to thrive after the completion of the human genome project 10 years ago. Thus far, more than 100 drug labels and clinical guidelines referring to pharmacogenomic biomarkers have been published, and several key pharmacogenomic markers for either drug safety or efficacy have been identified and subsequently adopted in clinical practice as pre-treatment genetic tests. However, a tremendous variation of genetic backgrounds exists between different ethnic groups. The application of pharmacogenomics in the Chinese population is still a long way off, since the published guidelines issued by the organizations such as US Food and Drug Administration require further confirmation in the Chinese population. This review highlights important pharmacogenomic discoveries in the Chinese population and compares the Chinese population with other nations regarding the pharmacogenomics of five most commonly used drugs, ie, tacrolimus, cyclosporine A, warfarin, cyclophosphamide and azathioprine.