Phenotyping Study of Cyclophosphamide 4-Hydroxylation in Malay Cancer Patients

Abstract

Background

Cyclophosphamide (CP) is an anticancer alkylating group (nitrogen mustard) and a prodrug that will be metabolized to form its active metabolite, 4-hydroxycyclophosphamide (4-OHCP). The various enzymes involved in its bioactivation can cause a wide range of CP expression and activity among patients and ultimately affect the metabolism, efficacy and toxicity of this drug. The effectiveness of CP therapy can be determined by 4-OHCP level in dried blood spot (DBS).

Aim

The purpose of this study was to conduct the phenotyping of CP 4-hydroxylation rate in Malay cancer patients.

Methodology

Phenotyping study of CP 4-hydroxylation rate to 40 subjects of Malay cancer patients was done based on the value of its bioactivity ratio (4-OHCP to CP levels).

Results

The result shown the cyclophosphamide 4-hydroxylation rate of 80% (n=32) subjects as ultrarapid metabolizer (UM) and 20% (n=8) as poor metabolizer (PM).

Conclusion

Phenotyping study of CP 4-hydroxylation in Malay cancer patients can be conducted by quantifying CP bioactivity ratio (4-OHCP to CP level) in dried blood spot. In majority of Malay cancer patients, cyclophosphamide would be bioactivated through 4-hydroxylation in hepar rapidly as indicated by the high value of the bioactivity ratio or the increased CP clearance and 4-OHCP level.

Keywords:

• 4-hydroxycyclophosphamide
• 4-OHCP
• 4-hydroxylation rate
• cyclophosphamide
• CP
• dried blood spots
• DBS
• Malay ethnicity

Acknowledgments

This study was supported by Directorate of Research and Community Services (DRPM) Universitas Indonesia with grant number: NKB-2095/UN2.RST/HKP.05.00/2020 and Dharmais Cancer Hospital, Jakarta, Indonesia.

Abbreviations

4-OHCP, 4-hydroxycyclophosphamide; AC, adriamycin+cyclophosphamide; CP, cyclophosphamide; CV, coefficient of variance; DBS, dried blood spot; diff, difference/bias; EM, extensive metabolizer; EMEA, European Medicines Agency; ESI, electrospray ionization; FAC, fluorouracil+adriamycin+cyclophosphamide; LLOQ, lower limit of quantification; m/z, ass per charge ratio; MRM, multiple reaction monitoring; MS/MS, tandem mass spectrometry; PM, poor metabolizer; QC, quality control; QCH, quality control high; QCL, quality control low; QCM, quality control medium; RCHOP, rituximab+cyclophosphamide+adriamycin+vincristine+prednisone; SN, subject number; TAC, docetaxel+adriamycin+cyclophosphamide; TC, docetaxel+cyclophosphamide; ULOQ, upper limit of quantification; UM, ultrarapid metabolizer; UPLC, ultra high performance liquid chromatography.

Ethics

This study was reviewed and approved by the Research Ethics Committees of “Dharmais” Cancer Hospital, Jakarta 11,420, Indonesia (No. 150/KEPK/VII/2019). This study was conducted in accordance with the Declaration of Helsinki.

Disclosure

The authors report no conflicts of interest in this work.