Characterizing Diffuse Large B Cell Lymphoma (DLBCL) Disease Biology Features and Survival Outcomes By Patient Racial Groups Using Real World Data

Background Various real world data (RWD) studies have highlighted differences in the survival outcomes of DLBCL patients of different ethnicities and racial groups. However, few studies have examined the differences in DLBCL biology features in patients of different racial groups. Using RWD, we evaluated both biology features and survival outcomes of DLBCL patients from different racial groups.

Method Our retrospective analysis used de-identified, real-world patient data from the Flatiron Health electronic health record-derived database. Inclusion criteria were patients with an initial diagnosis of DLBCL (ICD 9: 200x, 202x; ICD 10: C82x, C83x, C84x, C85x, C86x, C88x, C96x) between 1 January 2011 to 31 May 2022 and who had at least two documented clinical visits.

Patients’ racial groups were classified into Asian, Black or African American, White, Others and Unknown; the Others group were patients not included in the other racial groups. The DLBCL disease features included cell-of-origin (COO) subtypes, double hit status (MYC and BCL2 translocations), double expressor status (MYC and BCL2 expression by immunohistochemistry) and International Prognostic Index (IPI) scores. Differences among racial groups were examined using the chi-square test with p-value<0.05 considered significant. Differences in overall survival (OS) by patients racial groups were analyzed using Kaplan Meier survival analysis and an adjusted Cox regression model for multivariable analysis.

Results In total there were 8289 evaluable patients. The racial group distribution of the cohort was as follows: White (n = 5659, 68.3%), Others (n =1084, 13.1%) Black or African American ( n = 509, 6.1%), Asian (n = 185, 2.2%) and Unknown (n = 852, 10.3%); Fig. 1a.

Disease biology features among patients of different racial groups were evaluated. There was a significant difference in the racial distribution between the two COO subtypes (p=0.045). Higher proportion of White patients had the germinal-center B-cell-like (GCB) subtype (n=1888/3127, 60.4%) compared to Asian (n=58/119, 48.7%) and Others (n=351/626, 56.1%) patients. Asian patients had the highest proportion of activated B-cell-like (ABC) subtype (n=61/119, 51.3%) compared to the other racial groups. No significant difference in racial group distribution was seen in double hit status. In terms of double expressor status, there was a significant difference in racial distribution (p = 0.008). More Asian patients had positive double expressor status (n=30/185, 16.2%) compared to the other racial groups. Racial distribution was significantly different between IPI categories (p = 0.028). Higher proportion of White patients presented with higher IPI scores compared to Asian, Black or African American patients.

The univariate analysis showed that White patients had worse overall survival (median OS 85.3 months) than Black or African American patients (median OS 111.2 months), Asian patients (median OS 102.6 months) or Others patients (median OS 107.0 months); Fig. 1b. However, multivariable analysis, adjusted for age, gender, IPI and COO, showed no significant difference in OS between White patients and Black or African American (HR 0.89, 95% CI 0.75 - 1.06, p = 0.18) or Asian patients (HR 0.86, 95% CI 0.65 - 1.16, p = 0.31); though was a difference with the Others patients (HR 0.87, 95% CI 0.77-0.98, p =0.024) .

Conclusions Using a RWD cohort, we described the disease characteristics and OS between DLBCL patients of different racial groups. Although differences were seen in COO and IPI scores, OS was not significantly different between racial groups in multivariable analysis except between White and Others patients . As the Others patients were a heterogenous group, in-depth study is warranted in the future to delineate true differences.

Hiew:Roche Products Ltd: Current Employment; University Hospital Dorset: Ended employment in the past 24 months. Liu:Genesis Research: Current Employment. James:Genentech Inc.: Current Employment. Balasubramanian:Genentech Inc.: Current Employment. Bazeos:Roche Products Ltd.: Current Employment. Jiang:Whittington Health NHS Trust: Ended employment in the past 24 months; Roche Products Ltd: Current Employment.