Pharmacogenomic approaches for tailored anti-leukemic therapy in children

Systematic review: genetic polymorphisms in the pharmacokinetics of high-dose methotrexate in pediatric acute lymphoblastic leukemia patients

Variations in pharmacokinetic responses to high-dose methotrexate are essential for the prognosis and management of toxicity in the treatment of pediatric acute lymphoblastic leukemia (ALL) patients. This systematic review aimed to identify and evaluate genetic polymorphisms that are significantly associated with the pharmacokinetic parameters of methotrexate during the consolidation phase of pediatric ALL treatment. Using the Preferred Reporting Items for Systematic Reviews (PRISMA) guidelines, we systematically reviewed the literature from 2013 to 2023. The databases used were PubMed and Scopus. The outcomes of interest are the study design, patient characteristics, sample size, chemotherapy protocol utilized, pharmacokinetic parameters identified, and genetic polymorphisms implicated. We included 31 articles in the qualitative synthesis and found that the SLCO1B1, ABCB1, ABCC2, and MTHFR genes appear to play significant roles in MTX metabolism and clearance. Among these, variations in SLCO1B1 have the most significant and consistent impact on methotrexate clearance. These implicated variants may contribute to the precision and tailoring of HD-MTX treatment in pediatric ALL patients.

Genome wide association studies for treatment-related adverse effects of pediatric acute lymphoblastic leukemia

Acute lymphoblastic leukemia (ALL) is the most common pediatric hematological malignancy; notwithstanding the success of ALL therapy, severe adverse drugs effects represent a serious issue in pediatric oncology, because they could be both an additional life threatening condition for ALL patients per se and a reason to therapy delay or discontinuation with important fallouts on final outcome. Cancer treatment-related toxicities have generated a significant need of finding predictive pharmacogenomic markers for the a priori identification of at risk patients. In the era of precision medicine, high throughput genomic screening such as genome wide association studies (GWAS) might provide useful markers to tailor therapy intensity on patients' genetic profile. Furthermore, these findings could be useful in basic research for better understanding the mechanistic and regulatory pathways of the biological functions associated with ALL treatment toxicities. The purpose of this review is to give an overview of high throughput genomic screening of the last 10 years that had investigated the landscape of ALL treatment-associated toxicities. This article is categorized under: Cancer > Genetics/Genomics/Epigenetics.

Inhibition of autophagy potentiates anticancer property of 20(S)-ginsenoside Rh2 by promoting mitochondria-dependent apoptosis in human acute lymphoblastic leukaemia cells

Acute lymphoblastic leukaemia (ALL) is the most prevalent childhood malignancy. Although most children with ALL are cured, there is still a group of patients for which therapy fails owing to severe toxicities and drug resistance. Ginsenoside Rh2 (GRh2), a major bioactive component isolated from Panax ginseng, has been shown to have a therapeutic effect on some tumors. However, the molecular mechanisms of cell death induced by 20(S)-GRh2 in ALL cells remains unclear. In this study, we showed that 20(S)-GRh2 inhibited the cell growth and induced mitochondria-dependent apoptosis and autophagy. But it has no cytotoxic effect on human normal blood cells. Furthermore, autophagy plays a protective role in 20(S)-GRh2-induced apoptosis in ALL cell lines and human primary ALL cells. We demonstrated that either genetic or pharmacologic inhibition of autophagy could be more effective in reducing viability and enhancing 20(S)-GRh2-induced toxicity than 20(S)-GRh2 treatment alone. In addition, inhibition of autophagy could aggravate mitochondrial ROS generation and mitochondrial damage, and then accelerate mitochondria-dependent apoptosis. Taken together, these results suggest that inhibition of autophagy can sensitize ALL cells towards 20(S)-GRh2. The appropriate inhibition of autophagy could provide a powerful strategy to increase the potency of 20(S)-GRh2 as a novel anticancer agent for ALL therapy.

Pharmacogenetics and induction/consolidation therapy toxicities in acute lymphoblastic leukemia patients treated with AIEOP-BFM ALL 2000 protocol

Drug-related toxicities represent an important clinical concern in chemotherapy, genetic variants could help tailoring treatment to patient. A pharmacogenetic multicentric study was performed on 508 pediatric acute lymphoblastic leukemia patients treated with AIEOP-BFM 2000 protocol: 28 variants were genotyped by VeraCode and Taqman technologies, deletions of GST-M1 and GST-T1 by multiplex PCR. Toxicities were derived from a central database: 251 patients (49.4%) experienced at least one gastrointestinal (GI) or hepatic (HEP) or neurological (NEU) grade III/IV episode during the remission induction phase: GI occurred in 63 patients (12.4%); HEP in 204 (40.2%) and NEU in 44 (8.7%). Logistic regression model adjusted for sex, risk and treatment phase revealed that ITPA rs1127354 homozygous mutated patients showed an increased risk of severe GI and NEU. ABCC1 rs246240 and ADORA2A rs2236624 homozygous mutated genotypes were associated to NEU and HEP, respectively. These three variants could be putative predictive markers for chemotherapy-related toxicities in AIEOP-BFM protocols.

Dysplastic bone marrow changes during maintenance therapy for acute leukemia

We describe the case of an 8-year-old girl with common precursor B-cell acute lymphoblastic leukemia who presented with severe pancytopenia during maintenance therapy with methotrexate and 6-mercaptopurine. The bone marrow smear showed moderate hypocellularity and trilinear dysplastic changes consistent with a diagnosis of drug toxicity, with no evidence of lymphoblasts. Flow cytometric immunophenotyping was negative for leukemic cells. Blood cell counts normalized after treatment with folinic acid. Maintenance therapy was gradually restarted and she remained well at follow-up visits. Myelotoxicity from methotrexate and 6-mercaptopurine may represent an unpredictable incident during an otherwise uneventful maintenance therapy, and may occur independently of other organ toxicities.

TNF-α SNP rs1800629 and risk of relapse in childhood acute lymphoblastic leukemia: relation to immunophenotype

AIM

In the AIEOP-BFM ALL (Associazione Italiana Ematologia Oncologia Pediatrica-Berlin Frankfurt Münster acute lymphoblastic leukemia) 2000 protocol, 70% of relapsed patients had favorable prognostic features and fell within less intensive polychemotherapeutic regimens, suggesting the need for better assessing lower risk stratification.

MATERIALS & METHODS

A novel two-phase study design selected 614 children to be genotyped for TNF-α SNP rs1800629 (-308G>A). A weighted Cox model was applied to evaluate the SNP effect on hazard of relapse, adjusting for immunophenotype, risk group, age and gender and including interaction terms.

RESULTS

Significant interaction was found with immunophenotypes (p = 0.0007, with minor allele genotypes being adverse genetic markers in B-cell acute lymphoblastic leukemia and protective ones in T-cell acute lymphoblastic leukemia), and also with risk protocols (p = 0.0041, with minor allele genotypes as prognostic factor of relapse for standard risk patients [only one T-cell acute lymphoblastic leukemia in the subgroup analyzed]).

CONCLUSION

The presence of at least one A allele in TNF-α SNP rs1800629 should suggest a closer monitoring in B-cell acute lymphoblastic leukemia standard risk patients.

Pharmacogenetics of childhood acute lymphoblastic leukemia

Acute lymphoblastic leukemia (ALL) is the major pediatric cancer in developed countries. Although treatment outcome has improved owing to advances in chemotherapy, there is still a group of patients for which therapy fails while some patients experience severe toxicity. In the last few years, several pharmacogenetic studies have been performed to search for markers of outcome and toxicity in pediatric ALL. However, to date, TPMT is the only pharmacogenetic marker in ALL with clinical guidelines for drug dosing. In this article, we will provide an overview of the most important findings carried out in pharmacogenetics for pediatric ALL, such as the interest drawn by methotrexate transporters in the context of methotrexate treatment. Even if most of the studies are centered on coding genes, we will also point to new approaches focusing on noncoding regions and epigenetic variation that could be interesting for consideration in the near future.