Bioproperties, Nanostructured System and Analytical and Bioanalytical Methods for Determination of Rapamycin: A Review

The drug rapamycin is a potent inhibitor of the mTOR complex, acting directly in the signaling cascade of this protein complex; interrupting cell proliferation, in addition to being an extremely efficient immunosuppressant. Currently this drug is being used in several types of cancer. Rapamycin has been a target of great interest within nanomedicine involving nanostructured systems for drug delivery aiming to increase the bioactivity and bioavailability of this drug. In addition, there is a constant search for analytical methods to identify and quantify this drug. Numerous high-performance liquid chromatography analytical techniques, mass spectrometry and immunoassay techniques have been employed efficiently in an attempt to develop increasingly sensitive analytical methods. Thus, this review sought to bring together current and relevant scientific works involving rapamycin and; besides analytical methods more used for quantification of this molecule.

Comparison of LC-MS/MS and EMIT methods for the precise determination of blood sirolimus in children with vascular anomalies

Sirolimus (SRL) is a mammalian target of rapamycin (mTOR) inhibitor. The whole blood concentration of SRL is routinely monitored to tailor dosage and prevent toxicity. Currently, the enzyme multiplied immunoassay technique (EMIT) is often applied to perform therapeutic drug monitoring (TDM) of SRL, but the cross-reactivity with various metabolites is of great concern. A more specific method is required, such as liquid chromatography–tandem mass spectrometry (LC-MS/MS). However, no study on the method comparison of the EMIT and LC-MS/MS for the measurement of whole blood SRL concentration in children with vascular anomalies has been reported. This study developed a simple and sensitive LC-MS/MS assay for the determination of SRL. Meanwhile, consistency between LC-MS/MS and the EMIT was evaluated by linear regression and Bland–Altman analysis. Whole blood samples were deproteinized with methanol for erythrocyte lysis, and the resulting solution was injected into the LC-MS/MS system using the positive electrospray ionization mode. The multiple reaction monitoring transitions of m/z 931.7 → 864.6 and m/z 934.7 → 864.6 were used for SRL and SRL-d3 as the internal standards, respectively. The analytes were separated on a C18 column with a gradient mobile phase (0.1 mM formic acid and 0.05 mM ammonium acetate in methanol/ultrapure water). Blood samples collected from children with vascular anomalies undergoing SRL therapy were tested by EMIT and by LC-MS/MS. The linear range of LC-MS/MS was 0.500–50.0 ng/ml and that of the EMIT was 3.50–30.0 ng/ml. A significant positive correlation between the two assays was established with a regression equation described as [EMIT] = 1.281 × [LC−MS/MS] + 2.450 (r = 0.8361). Bland–Altman plots showed a mean concentration overestimation of 4.7 ng/ml [95% CI: (−3.1, 12.6)] and a positive bias of 63.1% [95% CI: (−36.1, 162.3)] generated by the EMIT more than that of by LC-MS/MS. In conclusion, the two methods were closely correlated, indicating that switching between the two methods is feasible. Considering the overestimation nature of the EMIT assay, switching from the EMIT to the LC-MS/MS method deserves close attention and necessary re-evaluation for the target therapeutic reference range, may be required when methods are switched within the same clinical laboratory or results are compared between different laboratories.

Expression of γ-globin genes in β-thalassemia patients treated with sirolimus: results from a pilot clinical trial (Sirthalaclin)

Introduction

β-thalassemia is caused by autosomal mutations in the β-globin gene, which induce the absence or low-level synthesis of β-globin in erythroid cells. It is widely accepted that a high production of fetal hemoglobin (HbF) is beneficial for patients with β-thalassemia. Sirolimus, also known as rapamycin, is a lipophilic macrolide isolated from a strain of Streptomyces hygroscopicus that serves as a strong HbF inducer in vitro and in vivo. In this study, we report biochemical, molecular, and clinical results of a sirolimus-based NCT03877809 clinical trial (a personalized medicine approach for β-thalassemia transfusion-dependent patients: testing sirolimus in a first pilot clinical trial, Sirthalaclin).

Methods

Accumulation of γ-globin mRNA was analyzed using reverse-transcription quantitative polymerase chain reaction (PCR), while the hemoglobin pattern was analyzed using high-performance liquid chromatography (HPLC). The immunophenotype was analyzed using a fluorescence-activated cell sorter (FACS), with antibodies against CD3, CD4, CD8, CD14, CD19, CD25 (for analysis of peripheral blood mononuclear cells), or CD71 and CD235a (for analysis of in vitro cultured erythroid precursors).

Results

The results were obtained in eight patients with the β+/β+ and β+/β0 genotypes, who were treated with a starting dosage of 1 mg/day sirolimus for 24-48 weeks. The first finding of this study was that the expression of γ-globin mRNA increased in the blood and erythroid precursor cells isolated from β-thalassemia patients treated with low-dose sirolimus. This trial also led to the important finding that sirolimus influences erythropoiesis and reduces biochemical markers associated with ineffective erythropoiesis (excess free α-globin chains, bilirubin, soluble transferrin receptor, and ferritin). A decrease in the transfusion demand index was observed in most (7/8) of the patients. The drug was well tolerated, with minor effects on the immunophenotype, and an only side effect of frequently occurring stomatitis.

Conclusion

The data obtained indicate that low doses of sirolimus modify hematopoiesis and induce increased expression of γ-globin genes in a subset of patients with β-thalassemia. Further clinical trials are warranted, possibly including testing of the drug in patients with less severe forms of the disease and exploring combination therapies.

Bioproperties, Nanostructured System and Analytical and Bioanalytical Methods for Determination of Rapamycin: A Review

The drug rapamycin is a potent inhibitor of the mTOR complex, acting directly in the signaling cascade of this protein complex; interrupting cell proliferation, in addition to being an extremely efficient immunosuppressant. Currently this drug is being used in several types of cancer. Rapamycin has been a target of great interest within nanomedicine involving nanostructured systems for drug delivery aiming to increase the bioactivity and bioavailability of this drug. In addition, there is a constant search for analytical methods to identify and quantify this drug. Numerous high-performance liquid chromatography analytical techniques, mass spectrometry and immunoassay techniques have been employed efficiently in an attempt to develop increasingly sensitive analytical methods. Thus, this review sought to bring together current and relevant scientific works involving rapamycin and; besides analytical methods more used for quantification of this molecule.

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.

Therapeutic drug monitoring of immunosuppressants by liquid chromatography-mass spectrometry

Immunosuppressant medications allow the transplantation of tens of thousands of allografts per year and consequently have great potential to decrease patient morbidity and mortality. However, some medications have great risk associated with over- and under-dosing leading to adverse effects or allograft rejection, respectively. This necessitates immunosuppressant therapeutic drug monitoring accomplished by immunoassay or liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). The former's accuracy can be hindered by metabolites of immunosuppressant medications, antibodies against these medications and heterophilic antibodies. Although LC-MS/MS has superior specificity which allows it to be less susceptible to interference, this methodology lacks standardization and the necessary throughput. Recent developments in LC-MS/MS quantitation, however, include patient-friendly sample submission as dried blood spots, higher sample throughput and commercialization. Here we critically review recent LC-MS/MS publications (January 2010 to July 2015) on the quantitation of cyclosporine A, tacrolimus, sirolimus and everolimus.

A simple and robust LC-MS/MS method for measuring sirolimus and everolimus in whole blood

Therapeutic drug monitoring of immunosuppressants sirolimus and everolimus is mandatory and liquid chromatography tandem mass spectrometry (LC-MS/MS) is the preferred technology for the measurement. Due to the high hydrophobicity these analytes bind to reverse-phase columns tightly and need column heating to elute. Column heating not only requires extra instrument preparation but also causes permanent column damage if the heater is left on while elution pumps stop by the end of the run. The primary improvement in the current method was to elute the analytes at room temperature using special buffers. This new LC-MS/MS method has been validated for clinical use and offers improved simplicity and robustness by eliminating column heating yet with high sensitivity, precision and accuracy.

Laboratory medicine and medical oncology: the tale of two Cinderellas

Cancer represents a leading cause of death in the developed countries. The past 50 years have witnessed major progress in both laboratory medicine and clinical oncology that has translated into improved prognosis of cancer patients. From the humble beginnings as unrelated specialties, major advances in the understanding of molecular bases of cancer progression led to increased interactions between laboratory medicine and clinical (mostly medical) oncology. Laboratory medicine is now an integral part of the management of cancer patients. The many aspects of the role of laboratory medicine in clinical oncology include the determination of biomarkers that are used in establishing the diagnosis, predicting response to therapy or prognosis, study of the host response to tumor growth, detection of treatment toxicity and determining the concentrations of anticancer drugs.

Immunosuppressant therapeutic drug monitoring by LC-MS/MS: workflow optimization through automated processing of whole blood samples

OBJECTIVES

Although, due to its high specificity and sensitivity, LC-MS/MS is an efficient technique for the routine determination of immunosuppressants in whole blood, it involves time-consuming manual sample preparation. The aim of the present study was therefore to develop an automated sample-preparation protocol for the quantification of sirolimus, everolimus and tacrolimus by LC-MS/MS using a liquid handling platform.

METHODS

Six-level commercially available blood calibrators were used for assay development, while four quality control materials and three blood samples from patients under immunosuppressant treatment were employed for the evaluation of imprecision. Barcode reading, sample re-suspension, transfer of whole blood samples into 96-well plates, addition of internal standard solution, mixing, and protein precipitation were performed with a liquid handling platform. After plate filtration, the deproteinised supernatants were submitted for SPE on-line. The only manual steps in the entire process were de-capping of the tubes, and transfer of the well plates to the HPLC autosampler.

RESULTS

Calibration curves were linear throughout the selected ranges. The imprecision and accuracy data for all analytes were highly satisfactory. The agreement between the results obtained with manual and those obtained with automated sample preparation was optimal (n=390, r=0.96). In daily routine (100 patient samples) the typical overall total turnaround time was less than 6h.

CONCLUSIONS

Our findings indicate that the proposed analytical system is suitable for routine analysis, since it is straightforward and precise. Furthermore, it incurs less manual workload and less risk of error in the quantification of whole blood immunosuppressant concentrations than conventional methods.