Impact of Extranodal Involvement on Outcomes with Chimeric Antigen Receptor T-Cell Therapy in B-Cell Non-Hodgkin Lymphoma

Introduction

Chimeric antigen receptor T-cell therapy (CART) has revolutionized the treatment algorithm of relapsed/refractory (R/R) B-cell non-Hodgkin lymphoma (NHL). However, approximately only 40% of cases achieve long-term durable remissions. Prognostication remains important as it would allow more precise prediction of outcomes and develop a personalized treatment approach. Currently, it is unclear whether prognostic factors that have been predictive of outcomes in the pre-CART era, remain important in the current era. We conducted a single center observational study to assess the prognostic significance of extra nodal involvement (ENI) on long-term outcomes following CART in B-cell NHL.

Methods

The primary aim was to evaluate the prognostic significance of ENI on long-term outcomes in patients with B-cell NHL treated with CART. The second aim was to specifically evaluate the impact of gastrointestinal (GI) involvement. Continuous variables were summarized as median (range) and categorical variables were reported as frequency (percentage). Kaplan-Meier method was used to estimate freedom from events at different time points and draw corresponding survival curves. Log-rank test was used to compare freedom from events between histology groups.

Results

74 patients were included in this analysis, with a median age of 62 (18-85) years. Fifty-three (72%) had evidence of ENI. Twenty-four (47%) had GI involvement as the sole site of ENI or with other sites of ENI. Forty-three (58%) patients were male and diffuse large B-cell lymphoma (DLBCL) was the most common histology (n=50 [54%]) followed by transformed follicular lymphoma (n=20 [27%]). Most patients had advanced stage disease at time of CART (n=71 [96%]) and 3 (4%) had CNS involvement at any time prior to CART. Median number of prior lines of systemic treatment were 2 (1-7) and 64 (87%) had progressive disease at time of CART. Axicabtagene ciloleucel was the most used CART product (n=68 [92%]); Grade 3-4 cytokine release syndrome was reported in 6 (8%) patients and grade 3-4 immune effector cell associated neurotoxicity syndrome was reported in 13 (18%) patients. ICU level of care was needed in 22 (30%) patients and 2 patients (3%) developed hemophagocytic lymphohistiocytosis-like syndrome. Sixty patients (87%) achieved an objective response and 34(49%) achieved a complete response. The 1-year OS was 66% (53-81) in patients who had ENI vs. 72% (54-97) in those without ENI (p=0.82); 1-year relapse rates were at 39% (20-54) vs. 36% (10-54) (p=0.95) for patients with ENI vs. those without ENI. No difference was noted between the two groups regarding progression-free survival and non-relapse mortality (NRM). No difference in outcomes was observed when patients who had GI involvement as the only site of ENI or in combination with other sites of ENI were compared to those who did not have GI involvement as one of the sites of ENI. Elevated LDH at the time of CART (HR 2.27 [95% CI 1.05-4.94], p=0.03), development of any grade ICANS (HR 2.77 [95% CI 1.27-6.04], p=0.01) and requirement for ICU level of care (HR 3.25 [95% CI 1.54-6.86], p=0.002) adversely affected OS; the impact of elevated LDH on OS remained significant in multivariate models (HR 2.34 [95% CI 1.05-5.27], p=0.04). Development of any grade CRS was associated with a decreased risk of relapse (HR 0.25 [95% CI 0.11-0.56], p=<0.001) and the requirement of ICU stay adversely affected NRM (HR 2.27 [95% CI 1.05-4.94], p=0.032).

Conclusion

These results suggest that ENI does not appear to be predictive of long-term outcomes in the setting of CART therapy. Patients who had ENI appeared to derive equal benefit from CART therapy. GI involvement as a site of ENI has been known to be associated with worse survival when compared to other sites of ENI but we did not observe any difference in this subgroup also. Evolving predictive models and/or biomarkers that take in account the dynamics of the interaction between the malignant and CART cells might help better inform prognostication in the current era.