Influx transporter variants as predictors of cancer chemotherapy-induced toxicity: systematic review and meta-analysis

A guide to plasma membrane solute carrier proteins

This review aims to serve as an introduction to the solute carrier proteins (SLC) superfamily of transporter proteins and their roles in human cells. The SLC superfamily currently includes 458 transport proteins in 65 families that carry a wide variety of substances across cellular membranes. While members of this superfamily are found throughout cellular organelles, this review focuses on transporters expressed at the plasma membrane. At the cell surface, SLC proteins may be viewed as gatekeepers of the cellular milieu, dynamically responding to different metabolic states. With altered metabolism being one of the hallmarks of cancer, we also briefly review the roles that surface SLC proteins play in the development and progression of cancer through their influence on regulating metabolism and environmental conditions.

Current management of chemotherapy-induced neutropenia in adults: key points and new challenges: Committee of Neoplastic Supportive-Care (CONS), China Anti-Cancer Association Committee of Clinical Chemotherapy, China Anti-Cancer Association

Chemotherapy-induced neutropenia (CIN) is a potentially fatal and common complication in myelosuppressive chemotherapy. The timing and grade of CIN may play prognostic and predictive roles in cancer therapy. CIN is associated with older age, poor functional and nutritional status, the presence of significant comorbidities, the type of cancer, previous chemotherapy cycles, the stage of the disease, specific chemotherapy regimens, and combined therapies. There are many key points and new challenges in the management of CIN in adults including: (1) Genetic risk factors to evaluate the patient's risk for CIN remain unclear. However, these risk factors urgently need to be identified. (2) Febrile neutropenia (FN) remains one of the most common reasons for oncological emergency. No consensus nomogram for FN risk assessment has been established. (3) Different assessment tools [e.g., Multinational Association for Supportive Care in Cancer (MASCC), the Clinical Index of Stable Febrile Neutropenia (CISNE) score model, and other tools] have been suggested to help stratify the risk of complications in patients with FN. However, current tools have limitations. The CISNE score model is useful to support decision-making, especially for patients with stable FN. (4) There are still some challenges, including the benefits of granulocyte colony stimulating factor treatment and the optimal antibiotic regimen in emergency management of FN. In view of the current reports, our group discusses the key points, new challenges, and management of CIN.

Pharmacogenomic Markers of Methotrexate Response in the Consolidation Phase of Pediatric Acute Lymphoblastic Leukemia Treatment

Methotrexate (MTX) is one of the staples of pediatric acute lymphoblastic leukemia (ALL) treatment. MTX targets the folate metabolic pathway (FMP). Abnormal function of the enzymes in FMP, due to genetic aberrations, leads to adverse drug reactions. The aim of this study was to investigate variants in pharmacogenes involved in FMP and their association with MTX pharmacokinetics (MTX elimination profile) and toxicity in the consolidation therapy phase of pediatric ALL patients. Eleven variants in the thymidylate synthetase (TYMS), methylenetetrahydrofolate reductase (MTHFR), dihydrofolate reductase (DHFR), SLC19A1 and SLCO1B genes were analyzed in 148 patients, using PCR- and sequencing-based methodology. For the Serbian and European control groups, data on allele frequency distribution were extracted from in-house and public databases. Our results show that the A allele of SLC19A1 c.80 variant contributes to slow MTX elimination. Additionally, the AA genotype of the same variant is a predictor of MTX-related hepatotoxicity. Patients homozygous for TYMS 6bp deletion were more likely to experience gastrointestinal toxicity. No allele frequency dissimilarity was found for the analyzed variants between Serbian and European populations. Statistical modelling did not show a joint effect of analyzed variants. Our results indicate that SLC19A1 c.80 variant and TYMS 6bp deletion are the most promising pharmacogenomic markers of MTX response in pediatric ALL patients.

The influence of single-nucleotide polymorphisms on overall survival and toxicity in cabazitaxel-treated patients with metastatic castration-resistant prostate cancer

PURPOSE

Cabazitaxel, used in patients with metastatic castration-resistant prostate cancer (mCRPC), is associated with adverse events which may require dose reductions or discontinuation of treatment. We investigated the potential association of single-nucleotide polymorphisms (SNPs) in genes encoding drug transporters and drug-metabolizing enzymes with cabazitaxel toxicity, overall survival (OS) and pharmacokinetics (PK).

METHODS

A total of 128 cabazitaxel-treated mCRPC patients, of whom prospectively collected data on toxicity and OS were available and 24 mCRPC patients with available cabazitaxel PK measurements, were genotyped using genomic DNA obtained from EDTA blood. The SLCO1B1 (388A > G; *1B; rs2306283 and 521 T > C; *5; rs4149056 and haplotype SLCO1B1*15), SLCO1B3 (334 T > G; rs4149117), CYP3A4 (*22; rs35599367), CYP3A5 (*3; rs776746), ABCB1 (3435C > T; rs1045642), and TUBB1 (57 + 87A > C; rs463312) SNPs were tested for their association with clinical and PK parameters by univariate/multivariate logistic regression, log-rank test, or Kruskal-Wallis test.

RESULTS

The SLCO1B1*15 haplotype was significantly associated with a lower incidence of leukopenia and neutropenia (p = 0.020 and p = 0.028, respectively). Patients harboring a homozygous variant for SLCO1B1*1B experienced higher rate ≥ grade 3 (p = 0.042). None of the SNPs were associated with pharmacokinetics or OS.

CONCLUSIONS

In this study, SLCO1B1 (SLCO1B1*15 and SLCO1B1*1B) was associated with cabazitaxel-induced adverse events in mCRPC patients. As the associations were opposite to previous studies in other drugs and contradicted an underlying pharmacokinetic rationale, these findings are likely to be false-positive and would ideally be validated with even larger (pharmacokinetic) cohorts.