Chronic myelogenous leukemia: A real-world experience from a Los Angeles county safety net hospital Free

Chronic myeloid leukemia (CML) is a myeloproliferative neoplasm characterized by the presence of the Philadelphia chromosome, resulting in the BCR-ABL1 fusion gene, and represents approximately 15%–20% of adult leukemias. Since the advent of small molecule tyrosine kinase inhibitors (TKIs) in the early 2000's, overall survival for CML at 5 year exceeds 90%. However, like all cancers, disparities with management frequently exist amongst minority populations due to demographics, behavioral factors, and access to medical services.

We performed a retrospective chart review of all patients aged greater than 18 years who presented to Harbor-UCLA Medical Center between 2015 and 2024 with the diagnosis of CML based on detection of the BCR-ABL1 fusion gene using reverse transcription polymerase chain reaction. Data collected included patient demographics, median income by zip code, CML phase and prognostic assessment at diagnosis, comorbid conditions, cell counts, treatment courses, treatment complications, details at relapse, and overall treatment response. Data entry was completed through the RedCap application. Subsequent analysis was conducted using descriptive statistics.

There were 108 patients with a diagnosis of CML who met the inclusion criteria. The median age at diagnosis was 47 years with 40% (n=43) female and 60% (n=65) male. Of these, 58.3% (n=63) were Hispanic, 13.9% (n=15) were African American, 3.7% (n=4) were White/Caucasian, 4.5% (n=5) Asian/Pacific Islander, and 19.4% (n=21) were other/unknown. 59% of patients had addresses in zip codes with average household incomes below the national average. Diagnosis of CML was made during chronic and accelerated phase in 92.6% and 5.6% of cases respectively. By Sokal score, 28.9%, 34.2%, and 36.8% had low, intermediate, and high-risk disease at diagnosis respectively. By Eutos score, 83.1% had low-risk and 16.9% had high-risk disease respectively. Mean WBC at diagnosis was 145,600/μL. First line treatment consisted of imatinib 65.7% (n=71), dasatinib 31.5% (n=34), nilotinib 0.9% (n=1), and unknown treatment 1.9% (n=2). During first line therapy, 46.5% of patients achieved major molecular response with a 3-log reduction (MMR3) or better at any time point. Reported issues with adherence to treatment were found in 47% of patients during first line therapy, with 41.7% of these due to reported side-effects leading to non-adherence. Discontinuation of first line therapy occurred in 58.3% (63/108) patients with the main reasons being inadequate response (30.4%), intolerance (51.8%), or both (17.9%). Average time to first line discontinuation was 14 months. 55.6% (60/108) of patients received second line treatment consisting of dasatinib 62.3% (n=38), imatinib 11.3% (n=7), nilotinib 8.1% (n=5), asciminib 9.7% (n=6), ponatinib 4.8% (n=3), bosutinib 1.6% (n=1) and interferon 3.2% (n=2). 42.9% of patients on second line therapy achieved MMR3 or better. Of the patients who received second line treatment, 56.7% (34/60) discontinued therapy with the main reasons being inadequate response (43.3%), intolerance (46.7%), or both (10.0%). Average time to second line discontinuation was 13 months. 27.8% (30/108) of patients went on to receive third line treatment that consisted of nilotinib 26.7% (n=8), dasatinib 20.0% (n=6), ponatinib 16.7% (n=5), imatinib 16.7% (n=5), bosutinib 13.3% (n=4), and asciminib 6.7% (n=2). 28.6% of patients on third line therapy achieved MMR3 or better. Of the patients who received third line treatment, 50.0% (16/30) discontinued therapy with the main reasons being inadequate response (26.7%), intolerance (40.0%), or both (33.3%). Average time to third line discontinuation was 15 months. 13.9% (15/108) of patients went on to receive fourth line therapy or beyond. In total, 37.0% (40/108) patients received mutational testing and 3.7% (n=4) were found to have a T315I mutation. A total of 4.6% (5/108) progressed to blast phase (3 during first line and 2 during second line treatment). Comorbid conditions were found in 82.4% of our patients.

This is the first study describing CML treatment in an almost exclusively underserved population. Compared to other populations, we found that our patients had a lower median age at diagnosis, were predominantly Hispanic, had lower rates of MMR with first line therapy, and received more lines of therapy overall.