Genetic Polymorphisms Associated with Vincristine Pharmacokinetics and Vincristine-Induced Peripheral Neuropathy in Pediatric Oncology Patients

Vincristine Disposition and Neurotoxicity Are Unchanged in Humanized CYP3A5 Mice

Previous studies have suggested that the incidence of vincristine-induced peripheral neuropathy (VIPN) is potentially linked with cytochrome P450 (CYP)3A5, a polymorphic enzyme that metabolizes vincristine in vitro, and with concurrent use of azole antifungals such as ketoconazole. The assumed mechanism for these interactions is through modulation of CYP3A-mediated metabolism, leading to decreased vincristine clearance and increased susceptibility to VIPN. Given the controversy surrounding the contribution of these mechanisms, we directly tested these hypotheses in genetically engineered mouse models with a deficiency of the entire murine Cyp3a locus [Cyp3a(-/-) mice] and in humanized transgenic animals with hepatic expression of functional and nonfunctional human CYP3A5 variants. Compared with wild-type mice, the systemic exposure to vincristine was increased by only 1.15-fold (95% confidence interval, 0.84-1.58) in Cyp3a(-/-) mice, suggesting that the clearance of vincristine in mice is largely independent of hepatic Cyp3a function. In line with these observations, we found that Cyp3a deficiency or pretreatment with the CYP3A inhibitors ketoconazole or nilotinib did not influence the severity and time course of VIPN and that exposure to vincristine was not substantially altered in humanized CYP3A5*3 mice or humanized CYP3A5*1 mice compared with Cyp3a(-/-) mice. Our study suggests that the contribution of CYP3A5-mediated metabolism to vincristine elimination and the associated drug-drug interaction potential is limited and that plasma levels of vincristine are unlikely to be strongly predictive of VIPN. SIGNIFICANCE STATEMENT: The current study suggests that CYP3A5 genotype status does not substantially influence vincristine disposition and neurotoxicity in translationally relevant murine models. These findings raise concerns about the causality of previously reported relationships between variant CYP3A5 genotypes or concomitant azole use with the incidence of vincristine neurotoxicity.

Neurologic Complications in Patients With Lymphoreticular Malignancy: A Descriptive Cohort Study

OBJECTIVES

The objectives of this study were to study the spectrum of neurologic complications in children with lymphoreticular malignancy (acute lymphoblastic leukemia, Hodgkin, and non-Hodgkin lymphoma) at diagnosis and during treatment and to determine the etiology of these complications.

MATERIALS AND METHODS

In this descriptive cohort study, conducted between November 2018 and March 2020, 204 children with a diagnosis of lymphoreticular malignancy were enrolled. The baseline investigations were done in all the cases. Those who developed neurological symptoms were evaluated with cerebrospinal fluid examination and radiologic and electrophysiologic studies as per indication and were managed according to standard management guidelines.

RESULTS

Of the 204 patients, 30 (14.7%) developed neurological complications. The majority of these complications (n=20/30; 87%) occurred during the intensive chemotherapy period. Common complications included acute methotrexate neurotoxicity (n=7), vincristine-induced neurotoxicity (n=7), central nervous system (CNS) relapse (n=4), and posterior reversible encephalopathy syndrome (n=2). L-asparaginase-induced thrombosis (n=1), intramedullary compression syndrome (n=1), CNS infection (n=2), CNS hemophagocytic lymphohistiocytosis (n=1), and steroid-induced myopathy (n=1) were also observed. The complications resolved in 21/30 (70%) patients after receiving appropriate treatment while the neurological complication persisted in 2/30 (6.7%) patients. Three patients (10%) abandoned the treatment, and 4 (13.3%) patients expired.

CONCLUSIONS

Neurologic complications in patients with lymphoreticular malignancy are quite variable, having common presenting symptoms but varying imaging abnormalities. By close follow-up and effective treatment, the morbidity and mortality of these complications can be minimized.

Evaluation of vincristine-induced peripheral neuropathy in children with cancer: Turkish validity and reliability study

BACKGROUND

The evaluation of peripheral neuropathy in children receiving Vincristine treatment is challenging. This study examined the Turkish validity and reliability of the Total Neuropathy Score-Pediatric Vincristine (TNS-PV) measurement tool, which can measure Vincristine-induced peripheral neuropathy symptoms in children with cancer.

METHODS

A total of 53 children aged 5-17 years who received Vincristine treatment in two pediatric hematology-oncology centers participated in the study. Data was collected using the Total Neuropathy Score-Pediatric Vincristine (TNS-PV), the Common Terminology Criteria for Adverse Events (CTCAE), the Wong-Baker FACES Pain Scale, and the Adolescent Pediatric Pain Tool (APPT). The correlation between the TNS-PV total score and other scales and the inter-rater reliability coefficient was evaluated.

FINDINGS

Of the children, 81.1% were diagnosed with ALL and 13.2% with Ewing Sarcoma. Cronbach's alpha values of form A and B of the TNS-PV scale were 0.628 and 0.639, respectively. As the cumulative Vincristine dose increased, the children's scores on TNS-PV were higher. A moderate and significant positive correlation was found between the TNS-PV form A total score and the worst subjective symptoms a, b (A), strength, tendon reflexes, and autonomic / constipation (r = 0.441, r = 0.545, r = 0.472, r = 0.536, p < 0.01).

DISCUSSION

The TNS-PV form B total score was found to have a moderate level, significant correlation with CTCAE sensory neuropathy score and Wong-Baker FACES Pain Scale, and a high level, significant positive correlation with CTCAE motor neuropathy score.

APPLICATION TO PRACTICE

The TNS-PV is valid and reliable for measuring Vincristine-induced peripheral neuropathy in practice in Turkish children 5 years and older.

The Crucial Findings Derived from the Special Issue "Inside Cancer Genomics: From Structure to Therapy"

Cancer initiation, growth, and progression are sustained by multiple types of genetic alterations, ranging in size from single point mutations, focal genomic errors to broad chromosomal copy number alterations, gains, and losses [...].

Proactive therapeutic drug monitoring of vincristine in pediatric and adult cancer patients: current supporting evidence and future efforts

Vincristine (VCR), an effective antitumor drug, has been utilized in several polytherapy regimens for acute lymphoblastic leukemia, neuroblastoma and rhabdomyosarcoma. However, clinical evidence shows that the metabolism of VCR varies greatly among patients. The traditional based body surface area (BSA) administration method is prone to insufficient exposure to VCR or severe VCR-induced peripheral neurotoxicity (VIPN). Therefore, reliable strategies are urgently needed to improve efficacy and reduce VIPN. Due to the unpredictable pharmacokinetic changes of VCR, therapeutic drug monitoring (TDM) may help to ensure its efficacy and to manage VIPN. At present, there is a lot of supporting evidence for the suitability of applying TDM to VCR therapy. Based on the consensus guidelines drafted by the International Association of Therapeutic Drug Monitoring and Clinical Toxicology (IATDMCT), this review aimed to summarize various available data to evaluate the potential utility of VCR TDM for cancer patients. Of note, valuable evidence has accumulated on pharmacokinetics variability, pharmacodynamics, drug exposure-clinical response relationship, biomarkers for VIPN prediction, and assays for VCR monitoring. However, there are still many relevant clinical pharmacological questions that cannot yet be answered merely based on insufficient evidence. Currently, we cannot recommend a therapeutic exposure range and cannot yet provide a dose-adaptation strategy for clinicians and patients. In areas where the evidence is not yet sufficient, more research is needed in the future. The precision medicine of VCR cannot rely on TDM alone and needs to consider the clinical, environmental, genetic background and patient-specific factors as a whole.

Vincristine-Induced Acrocyanosis and Erythema Pernio

INTRODUCTION

Acrocyanosis and erythema pernio are 2 dermatologic manifestations of vasospastic changes. Primary care providers should consider that these conditions can occur as primary or idiopathic conditions and as secondary conditions related to another disease or medication. Herein we describe a case of acrocyanosis and erythema pernio attributed to vincristine therapy.

CASE DESCRIPTION

A 22-year-old man was evaluated for discomfort and red lesions involving the toes of both feet for several weeks. He had completed chemotherapy 1 month earlier for Ewing sarcoma in the right femur. Local control for the primary tumor included wide local excision and reconstruction with a vascularized fibular allograft from the right fibula. On examination, his right foot was dark blue and cool. Toes on both feet had nonpainful erythematous papules. After the case was discussed with the patient's oncology team, the diagnosis was medication-induced acrocyanosis of the right foot and bilateral erythema pernio. Treatment consisted of supportive care to keep the feet warm and promote circulation to the feet. At 2-week follow-up, the patient's symptoms and the appearance of his feet had markedly improved.

DISCUSSION

Primary care clinicians should be able to recognize dermatologic manifestations of vasospastic changes, including acrocyanosis and erythema pernio, and rule out possible secondary causes, such as pharmacologic agents. This patient's history of therapy for Ewing sarcoma prompted consideration of medication-induced vasospastic changes most likely related to the adverse vasospastic effects of vincristine. Symptoms should improve with cessation of the offending medication.