Tamoxifen Dose Adjustment on Indonesian Female ER+ Breast Cancer Patients Based on CYP2D6 Genotype and Endoxifen Levels
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ClinicalTrials.gov Identifier: NCT04312347 |
Recruitment Status :
Completed
First Posted : March 18, 2020
Last Update Posted : August 5, 2021
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Condition or disease | Intervention/treatment | Phase |
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ER+ Breast Cancer | Drug: Tamoxifen dose adjustment | Not Applicable |
Study Type : | Interventional (Clinical Trial) |
Actual Enrollment : | 151 participants |
Allocation: | N/A |
Intervention Model: | Single Group Assignment |
Masking: | None (Open Label) |
Primary Purpose: | Treatment |
Official Title: | Tamoxifen Dose Adjustment on ER+ Breast Cancer Patients Based on Genomic and Metabolite Concentrations Analysis |
Actual Study Start Date : | September 6, 2019 |
Actual Primary Completion Date : | May 1, 2021 |
Actual Study Completion Date : | June 30, 2021 |

Arm | Intervention/treatment |
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Experimental: Personalized dosing of tamoxifen
Increase tamoxifen dose into 40 mg/day for patients with low endoxifen level and poor/intermediate metabolizer CYP2D6 phenotype.
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Drug: Tamoxifen dose adjustment
Patients with low endoxifen level and poor/intermediate metabolizer CYP2D6 phenotype will receive tamoxifen dose escalation into 40 mg/day. |
- Effects of genotype and phenotype of CYP2D6 on plasma and serum concentration of tamoxifen and its metabolites [ Time Frame: 8 weeks after initial tamoxifen intake ]
- Effects of dose recommendation of tamoxifen based on CYP2D6 genotyping results on endoxifen levels [ Time Frame: 8 weeks after dose recommendation ]
- Frequencies of CYP2D6 alleles in female Indonesian population [ Time Frame: Baseline, pre-intervention ]

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Ages Eligible for Study: | 18 Years and older (Adult, Older Adult) |
Sexes Eligible for Study: | Female |
Accepts Healthy Volunteers: | No |
Inclusion Criteria:
- Diagnosed with ER+ breast cancer
- Have taken tamoxifen daily for at least 2 months
Exclusion Criteria:
- Have not taken tamoxifen daily for at least 2 months

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.
Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT04312347
Indonesia | |
MRCCC Siloam Hospital Semanggi | |
Jakarta, DKI Jakarta, Indonesia, 12930 |
Principal Investigator: | Baitha P. Maggadani | Department of Pharmacy, University of Indonesia |
Responsible Party: | Nalagenetics Pte Ltd |
ClinicalTrials.gov Identifier: | NCT04312347 |
Other Study ID Numbers: |
TMS01190510 |
First Posted: | March 18, 2020 Key Record Dates |
Last Update Posted: | August 5, 2021 |
Last Verified: | March 2020 |
Studies a U.S. FDA-regulated Drug Product: | No |
Studies a U.S. FDA-regulated Device Product: | No |
breast cancer tamoxifen CYP2D6 endoxifen |
Breast Neoplasms Neoplasms by Site Neoplasms Breast Diseases Skin Diseases Tamoxifen Estrogen Antagonists Hormone Antagonists |
Hormones, Hormone Substitutes, and Hormone Antagonists Physiological Effects of Drugs Antineoplastic Agents, Hormonal Antineoplastic Agents Selective Estrogen Receptor Modulators Estrogen Receptor Modulators Bone Density Conservation Agents |