(PA-451) Evaluating Racial and Ethnic Disparities in Progression Assessment Patterns in Routine Clinical Practice Among Patients with Newly Diagnosed Multiple Myeloma

Globally, multiple myeloma (MM) is the second most common hematologic malignancy. Underrepresented minorities (URM) may lack access to care, resulting in disparities. Disease progression in MM is based on assay results specified in the International Myeloma Working Group (IMWG) Uniform Response Criteria. This research aimed to understand differences in progression assessment patterns in routine clinical practice among URM to elucidate potential disparities in care.

Methods:   

We included newly diagnosed multiple myeloma (NDMM) patients starting on first line of therapy (1L) from the Flatiron Health Research Database (2011 - 2023). Recommended assays as per consensus guidelines to evaluate disease progression include serum protein electrophoresis (SPEP), 24hr urine protein electrophoresis (UPEP), and free light chains (FLC). P</span>atterns and cadence of assays collected at each progression assessments were characterized for racial and ethnic (R&E) groups: Non-Hispanic White (NHW; N=7,178), Hispanic (N=904), Non-Hispanic Black (NHB; N=2,159), Non-Hispanic Asian (NHA, N = 226), and Non-Hispanic Other Races (NHO, N = 749). Testing patterns were characterized at baseline (90 days prior to 7 days post 1L initiation) and on-treatment (8 days post 1L initiation through the end of 1L) periods. Stratified analysis by factors such as age and socioeconomic status (SES) were explored to understand their impact on the assessment pattern and cadence in URMs.

Results:   

The most common assessment pattern was combined SPEP + FLC, conducted across R&E groups during baseline (33-48%) and similarly on-treatment period among all assessment episodes (41-52%). This was followed by individual assessments during baseline (FLC:15-24%, SPEP:10-13%) and on-treatment period (SPEP: 20-29%, FLC:18-29%), respectively. UPEP was infrequently utilized during baseline (6-11%) and on-treatment period (1-3%). Patterns remained consistent in analyses stratifying on age, transplant reception and SES. The Hispanic and NHO groups appeared to have slightly lower rates of having any IMWG tests recorded during on-treatment period when compared with other groups, in the full cohort (80%-83 % compared to 85%-89%) and in stratified analyses.

The median time between IMWG assays was 28 days across all patients, irrespective of R&E group. This was consistent when stratified by age, transplant reception, SES, and treatment start year, except in transplant recipients, where median time was 21 days.

Conclusions:   

Assay collection patterns and cadence were consistent during baseline and on-treatment periods among NDMM patients in 1L, suggesting no observed disparities in progression assessment in URMs. Further evaluation of real-world progression endpoints is needed to understand if there are meaningful differences in MM assay collection across URM in later lines of treatment or other real-world populations.