Jerald Radich

The goal of the “Spot On CML” program is to provide diagnostic and monitoring tests to chronic myeloid leukemia (CML) patients in low- and middle-income countries (LMICs). Previously, we demonstrated reproducible BCR::ABL1 transcript quantification using dried blood spots (DBS). We have now optimized methods of DNA and RNA extraction from DBS, allowing the detection of myeloid gene variants, including ABL1 tyrosine kinase domain mutations. Among 177 CML patients from nine countries, ABL1 mutations were identified in 61 (34%) patients, with multiple mutations present in some cases. The most common ABL1 mutation was T315I (45.9% of patients with ABL1 mutations). Among 69 patients, 89 Tier I–II variants (pathogenic or likely pathogenic) were identified in other genes, including 52 ASXL1 variants in 49 patients. The detection of ASXL1 variants correlated strongly with the presence of ABL1 mutations (P = 3.51E-04). These methodologies are directly applicable to all assays used for the diagnosis, prognosis, and monitoring of CML and have important implications in bringing state-of-the-art genetic analysis to CML patients in LMICs.

Measurable residual disease (MRD) is a strong but imprecise predictor of relapse in acute myeloid leukemia. Many patients fall into the outlier categories of MRD positivity without relapse or MRD negativity with relapse. Why? We will discuss these states in the context of “clonal ontogeny” examining how mutations, clonal structure, and Darwinian rules impact response, resistance, and relapse.

Purpose of Review The study aims to evaluate the impact of COVID-19 on the delivery of health care and services to patients with chronic myeloid leukemia in low- and middle-income countries (LMICs) accessing treatment through The Max Foundation. Recent Findings An online survey was developed and sent via email to 527 partner physicians who had active patients under their care in July 2020, asking about the disruption of health services with multiple-choice answers or a five-point ordinal scale. Data from The Max Foundation’s Patient Access Tracking System (PATS®) was analyzed to evaluate program performance in 2020 compared with 2019. PATS® is used to track key patient information and supply chain data to ensure robust reporting, quality assurance, and safety. Among the 111 physicians who responded (20% response rate), 48% reported that someone on their team had contracted COVID-19. A total of 95 (85%) physicians reported at least some disruption of services to patients due to COVID-19, with 29 (26%) reporting frequent or complete disruption. Almost all physicians in the South Asia and Asia Pacific regions reported disruption (96% and 95%, respectively), compared with three quarters of physicians in Latin America. Institutions overcame challenges using a variety of solutions including telemedicine (60%), electronic prescriptions (45%), home delivery via courier services (31%), government workers (9%), and dispensation coordination with regional hospitals (14%). Summary The COVID-19 pandemic has disrupted services for CML physicians and patients worldwide. Overall, these disruptions did not appear to significantly affect The Max Foundation’s ability to provide patients with access to treatment, as novel approaches in telemedicine, supply chain, and dispensing, as well as provision of guidance and support for physicians were utilized to overcame disruption of services.

Tyrosine kinase inhibitor therapy revolutionized chronic myeloid leukemia treatment and showed how targeted therapy and molecular monitoring could be used to substantially improve survival outcomes. We used chronic myeloid leukemia as a model to understand a critical question: why do some patients have an excellent response to therapy, while others have a poor response? We studied gene expression in whole blood samples from 112 patients from a large phase III randomized trial (clinicaltrials gov. Identifier: NCT00471497), dichotomizing cases into good responders (BCR::ABL1 ≤10% on the International Scale by 3 and 6 months and ≤0.1% by 12 months) and poor responders (failure to meet these criteria). Predictive models based on gene expression demonstrated the best performance (area under the curve =0.76, standard deviation =0.07). All of the top 20 pathways overexpressed in good responders involved immune regulation, a finding validated in an independent data set. This study emphasizes the importance of pretreatment adaptive immune response in treatment efficacy and suggests biological pathways that can be targeted to improve response.

Chronic myelogenous leukemia (CML) is a hematopoietic stem cell malignancy that accounts for 15–20% of all cases of leukemia. CML is caused by a translocation between chromosomes 9 and 22 which creates an abnormal fusion gene, BCR::ABL1. The amount of BCR::ABL1 transcript RNA is a marker of disease progression and the effectiveness of tyrosine kinase inhibitor (TKI) treatment. This study determined the analytical and clinical performance of a droplet digital PCR based assay (QXDx BCR-ABL %IS Kit; Bio-Rad) for BCR::ABL1 quantification. The test has a limit of detection of MR4.7 (0.002%) and a linear range of MR0.3–4.7 (50–0.002%IS). Reproducibility of results across multiple sites, days, instruments, and users was evaluated using panels made from BCR::ABL1 positive patient samples. Clinical performance of the assay was evaluated on patient samples and compared to an existing FDA-cleared test. The reproducibility study noted negligible contributions to variance from site, instrument, day, and user for samples spanning from MR 0.7–4.2. The assay demonstrated excellent clinical correlation with the comparator test using a Deming regression with a Pearson R of 0.99, slope of 1.037 and intercept of 0.1084. This data establishes that the QXDx^™ BCR-ABL %IS Kit is an accurate, precise, and sensitive system for the diagnosis and monitoring of CML.