Individual prediction of nonadherence to oral mercaptopurine in children with acute lymphoblastic leukemia: Results from COG AALL03N1

Additive effects of TPMT and NUDT15 on thiopurine toxicity in children with acute lymphoblastic leukemia across multiethnic populations

BACKGROUND

Thiopurines such as mercaptopurine (MP) are widely used to treat acute lymphoblastic leukemia (ALL). Thiopurine-S-methyltransferase (TPMT) and Nudix hydrolase 15 (NUDT15) inactivate thiopurines, and no-function variants are associated with drug-induced myelosuppression. Dose adjustment of MP is strongly recommended in patients with intermediate or complete loss of activity of TPMT and NUDT15. However, the extent of dosage reduction recommended for patients with intermediate activity in both enzymes is currently not clear.

METHODS

MP dosages during maintenance were collected from 1768 patients with ALL in Singapore, Guatemala, India, and North America. Patients were genotyped for TPMT and NUDT15, and actionable variants defined by the Clinical Pharmacogenetics Implementation Consortium were used to classify patients as TPMT and NUDT15 normal metabolizers (TPMT/NUDT15 NM), TPMT or NUDT15 intermediate metabolizers (TPMT IM or NUDT15 IM), or TPMT and NUDT15 compound intermediate metabolizers (TPMT/NUDT15 IM/IM). In parallel, we evaluated MP toxicity, metabolism, and dose adjustment using a Tpmt/Nudt15 combined heterozygous mouse model (Tpmt+/-/Nudt15+/-).

RESULTS

Twenty-two patients (1.2%) were TPMT/NUDT15 IM/IM in the cohort, with the majority self-reported as Hispanics (68.2%, 15/22). TPMT/NUDT15 IM/IM patients tolerated a median daily MP dose of 25.7 mg/m2 (interquartile range = 19.0-31.1 mg/m2), significantly lower than TPMT IM and NUDT15 IM dosage (P < .001). Similarly, Tpmt+/-/Nudt15+/- mice displayed excessive hematopoietic toxicity and accumulated more metabolite (DNA-TG) than wild-type or single heterozygous mice, which was effectively mitigated by a genotype-guided dose titration of MP.

CONCLUSION

We recommend more substantial dose reductions to individualize MP therapy and mitigate toxicity in TPMT/NUDT15 IM/IM patients.

Paediatric medicine issues and gaps from healthcare workers point of view: survey results and a narrative review from the global accelerator for paediatric formulations project

The WHO Model List of Essential Medicines for Children (EMLc) has not been systematically revised in the last few years. We conducted a survey addressed to healthcare professionals prescribing, preparing, or administering medicines to children and a narrative review to identify problematic paediatric formulations or missing medicines in all therapeutic fields to inform the review of the EMLc in 2023. A total of 285 physicians (63%), 28 nurses (6%) and 142 pharmacists (31%), mostly working in the hospital setting, reported at least one problematic medicine. 290 medicines were reported as missing (completely or the child-appropriate formulation). The top three most mentioned were ciprofloxacin together with phenobarbital and omeprazole. 387 medicines were reported as problematic (34% were oral liquid formulations, 34% tablets, 18% parenteral preparations. Mostly of the products were antibacterials (27%), cardiovascular medicines (11%) and antivirals (11%). The obtained responses show the perspective of healthcare workers working around the world, particularly in the European region (25%), in the African region (24%), and in the Region of the Americas (19%), with limited representation from Northern Africa and the Middle East. Our results need to be analysed with the outputs of other ongoing works before specific products can enter the WHO-hosted Global Accelerator for Paediatric formulations network prioritisation process. Efforts to develop appropriate formulations for children should be accelerated so that the uncertainties associated with off-label drug preparation and use are minimised, and therapeutic benefits are optimised.

Building new standards to prevent harm from medication errors in children with cancer

Children with cancer receive many medications outside the hospital administered by their caregivers. The study by Walsh et al. shows the number and types of medication errors in these patients. The study includes data from three different centers. Importantly, the study shows the types of errors that cause harm. The authors describe how the harmful errors can be prevented. We suggest ways these results can be used to identify which patients and families will benefit from additional attention. Providing more help at clinic and in the home may help prevent harmful medication errors in children with cancer.

Barriers to medication adherence among adolescents and young adults with cancer

BACKGROUND

Adherence promotion is a critical component of adolescent and young adult (AYA) cancer care, but predictors of nonadherence that could be targeted in intervention efforts remain largely unknown. The purpose of this multi-site longitudinal observational study was to examine the relationship between barriers and medication adherence among AYAs with cancer.

PROCEDURE

Sixty-five AYAs (ages 15-24 years; mean age = 18.97 years, SD = 2.51; Mmean time since diagnosis = 1.42 years, SD = 1.95) with newly diagnosed or relapsed cancer completed self-report measures of barriers and adherence at quarterly study visits and used an electronic adherence monitoring device for 12 months. Longitudinal mixed effects models were used to examine our primary hypothesis that greater barriers are related to lower adherence over time. Descriptive statistics were used to explore our secondary aim of describing the frequency and patterns of barriers endorsed by AYAs with cancer.

RESULTS

After controlling for covariates (time, medication type, race, ethnicity, diagnosis, time since diagnosis), a greater number of barriers was associated with lower electronically monitored (β = -5.99, p = .005) and self-reported (β = -1.92, p < .001) adherence. The specific barriers endorsed by AYAs differed across participants, and the majority of AYAs endorsed an entirely different pattern of barriers than any other AYA in the study.

CONCLUSION

Barriers are associated with nonadherence and may be a promising target for intervention. Individual variability across barriers, however, suggests that tailoring may be necessary, and a promising next step is to explore personalized approaches to adherence promotion.

Adherence to Oral Chemotherapy in Acute Lymphoblastic Leukemia during Maintenance Therapy in Children, Adolescents, and Young Adults: A Systematic Review

Acute lymphoblastic leukemia (ALL) is the most common malignancy in children and young adults. Treatment is long and involves 2-3 years of a prolonged maintenance phase composed of oral chemotherapies. Adherence to these medications is critical to achieving good outcomes. However, adherence is difficult to determine, as there is currently no consensus on measures of adherence or criteria to determine nonadherence. Furthermore, there have been few studies in pediatric B-ALL describing factors associated with nonadherence. Thus, we performed a systematic review of literature on oral chemotherapy adherence during maintenance therapy in ALL following PRISMA guidelines. Published studies demonstrated various objective and subjective methods of assessing adherence without generalizable definitions of nonadherence. However, the results of these studies suggested that nonadherence to oral maintenance chemotherapy was associated with increased risk of relapse. Future studies of B-ALL therapy should utilize a uniform assessment of adherence and definitions of nonadherence to better determine the impact of nonadherence on B-ALL outcomes and identify predictors of nonadherence that could yield targets for adherence improving interventions.

Disparities in trial enrollment and outcomes of Hispanic adolescent and young adult acute lymphoblastic leukemia

Contrary to population data, survival of Hispanic AYA ALL patients enrolled on CALGB 10403 was equivalent to non-Hispanic patients.

Geographical alignment between Hispanic patient incidence and trial sites may increase Hispanic patient enrollment onto clinical trials.

In this secondary analysis of Hispanic adolescents and young adults (AYA) with acute lymphoblastic leukemia (ALL) treated on Cancer and Leukemia Group B (CALGB) 10403, we evaluated outcomes and geographic enrollment patterns relative to US population data. We used demographic, clinical, and survival data on AYAs enrolled on CALGB 10403 (N = 295, 2007-2012). Surveillance, Epidemiology, and End Results registries provided overall survival (OS) for US AYA ALL by ethnicity/race. North American Association of Cancer Registries provided AYA ALL incidence overall and proportion among Hispanics by US state. Of AYAs enrolled on CALGB 10403, 263 (89%) reported ethnicity/race: 45 (17%) Hispanic, 172 (65%) non-Hispanic White (NHW), 25 (10%) non-Hispanic Black (NHB), and 21 (8%) other. Compared with NHWs, Hispanic and NHB patients had lower household income, and Hispanic patients were more likely to harbor high-risk CRLF2 aberrations. Relative to US estimates, where Hispanic patients represented 46% of newly diagnosed AYA ALL patients and experienced inferior OS compared with NHW (P < .001), Hispanic AYAs on CALGB 10403 did as well as NHW patients (3 year OS, 75% vs 74%; P = NS). Hispanic patients also had higher rates of protocol completion (P = .05). Enrollments on CALGB 10403 differed relative to the distribution of Hispanic AYA ALL in the United States: enrollment was highest in the Midwest; t and only 15% of enrollees were from states with a high proportion of Hispanic AYA ALL patients. In summary, Hispanic patients treated on CALGB 10403 did as well as NHWs and better than population estimates. Geographical misalignment between trial sites and disease epidemiology may partially explain the lower-than-expected enrollment of Hispanic AYA ALL patients.

Strategies to Optimize Adherence in Patients with Mycosis Fungoides

Patient adherence to medications for common skin conditions has been extensively studied over the past two decades, and suboptimal adherence is a primary contributor to treatment failure. The impact of sub-par adherence in cutaneous T-cell lymphoma (CTCL) patients has been largely unexplored, and promoting adherence in this patient population may represent a promising area of consideration for improving treatment outcomes. We apply patient adherence strategies that have been studied in dermatology to CTCL and provide concrete examples of how these strategies can be used to improve adherence in the CTCL setting. Through the implementation of small changes in how we present and counsel about therapeutic options to our patients, we can maximize patient adherence, which has the potential to optimize therapy regimens and reduce treatment failure.