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Impact of Genetic Variants on the Toxicity of Antibody-Drug Conjugates in Locally Advanced or Metastatic Breast Cancer: The Role of the UGT1A1 Gene as a Predictive Biomarker of Therapeutic Response

RECRUITINGSponsored by Fundación Pública Andaluza para la Investigación Biomédica Andalucía Oriental
Actively Recruiting
SponsorFundación Pública Andaluza para la Investigación Biomédica Andalucía Oriental
Started2025-07-15
Est. completion2026-12-31
Eligibility
Age18 Years+
Healthy vol.Accepted

Summary

The metabolism of anticancer drugs is influenced by genetic variants that affect their bioavailability and toxicity. In the case of antibody-drug conjugates (ADCs), such as sacituzumab-govitecan (SG), trastuzumab-deruxtecan (T-DXd), and datopotamab-deruxtecan (Dato-DXd), the enzyme UDP-glucuronosyltransferase 1A1 (UGT1A1) plays a central role in the glucuronidation and elimination of their cytotoxic components. In particular, the metabolism of SN-38, the active metabolite of irinotecan and SG, is highly influenced by variants in UGT1A1, leading to drug accumulation and the development of severe toxicities. Patients with variants such as UGT1A1\*28 (rs3064744) and UGT1A1\*6 (rs4148323) exhibit reduced enzyme activity, increasing the risk of neutropenia and severe diarrhea. The relevance of UGT1A1 is not limited to sacituzumab-govitecan; its role in the elimination of camptothecin derivatives suggests it could also impact the toxicity of trastuzumab-deruxtecan and datopotamab-deruxtecan, which contain deruxtecan, a cytotoxic agent 10 times more potent than irinotecan. Despite strong evidence linking the UGT1A1 genotype to irinotecan toxicity, there are currently no established pharmacogenetic recommendations for antidiuretic peptides (ADCs) in metastatic breast cancer.

Eligibility

Age: 18 Years+Healthy volunteers accepted
Inclusion Criteria:

* Patients aged 18 years or older.
* Patients diagnosed with breast cancer starting or undergoing treatment with Sacituzumab Govitecan, Trastuzumab Deruxtecan, or Datopotamab Deruxtecan.
* Provision of signed informed consent for the genetic study.

Exclusion Criteria:

* Patients who are ultimately not treated with the specified Antibody-Drug Conjugates.
* Refusal to provide informed consent for genetic analysis.

Conditions5

Breast CancerCancerDrug-Related Side Effects and Adverse ReactionsMetastatic Breast CancerPharmacogenetic Variant

Interventions3

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