Clinical Outcome of Refractory Lymphoma Patients with Non Response to Chimeric Antigen Receptor T Cell Therapy
Authors: Amisha Fnu , Kakadia Sunilkumar , Mukherjee Akash 
Published: November 2021

Abstract
Background
Chimeric antigen receptor T cell (CART) therapy has remarkably improved the outcome of patients (pts) with relapsed refractory B cell non-Hodgkin lymphoma. Anti-CD19 directed CART therapy have shown to yield durable remission in 40%-50% of patients with relapsed refractory (r/r) diffuse large B cell lymphoma (Neelapu et al. NEJM 2017; NCT 02348216). However, pts who had disease progression post CART therapy (non-responders) have poor outcomes. There is paucity of information regarding negative predictors for disease progression and outcome of non-responders post CART therapy.
Methods
We conducted a single center retrospective study of 11 patients with relapsed refractory large B cell lymphoma who underwent treatment with CART in our institution from December 2019 to June 2021 and further studied the baseline characteristics, and clinical outcome of 8 pts who were non responders to CART therapy.
Results
All patients received low dose fludarabine cyclophosphamide based lymphodepleting conditioning regimen followed by anti-CD19 directed CART cells using CD28 as costimulatory domain with a target dose of 2 x 10 6 cells /kilogram of body weight.
Baseline characteristics as shown in [Table 1]. Median age at CART therapy was 61 years (range 49-71). Median ECOG score at CART therapy was 1. All patients had chemo refractory disease at time of CART therapy with 9 patients having refractory diffuse large B cell lymphoma and 2 patients had transformed large B cell lymphoma. Genomic studies showed high risk disease in 4 patients with double hit lymphoma, 3 patients with complex cytogenetics with one having 17 p deletion and 2 patients with double expressors of c-myc and bcl2. Only 5 patients had available Ki-67 score &gt; 80%. All patients had stage III-IV disease at the time of CART therapy. Seven pts had extra nodal disease and one patient had CNS involvement. Median R-IPI score at time of CART therapy was 3 (range 2-4). Median LDH, serum ferritin and serum CRP at the time of CART therapy was 388 (range 136-1489); 831 (range 116.9-1503); and 28.1 (range 7.4-226) respectively. Median number of prior therapies were 3 (range 2-9). One patient had prior autologous stem cell transplant. Median absolute lymphocyte count (ALC) and platelet count at CART therapy was 0.01/ul (range 0.01-2.5) and 89 x 10 3/ul (range 10-385) respectively. Median time from last salvage chemotherapy to CART therapy was 62 days (range 28-492).
Total six pts had cytokine release syndrome (CRS) with median time for CRS onset was 3.5 days (range 1-8) with all of them having grade 1-2 CRS. Total seven pts had neurotoxicity with median time for onset was 5 days (range 1-41) post CART with 4 pts having &gt; grade 3 immune effector cell associated neurotoxicity syndrome (ICANS). Overall, six and seven pts received tociluzumab and steroids respectively for treatment of CART related CRS and ICANS. Day 30 PET/CT scan showed three responders (2CR,1PR) and eight non responder patients with disease progression.
Non responder pts to CART, when compared with responders had higher value of median LDH (438 vs 300; p = 0.92); median CRP (29 vs 13; p = 0.497) ; higher extra nodal involvement ( 6 pts vs one), median R-IPI score at the time of CART ( 4 vs 3), median number of prior therapies (4 vs 3), and median time from last salvage therapy to CART ( 73 days vs 50 days ; p = 0.91). No difference in baseline ALC count and platelet count was noted between the two groups. Compared to responders, non-responder pts had lower incidence of CRS (100% vs 37.5%) and ICANS (100% vs 50%). Post CART therapy, non-responder pts were treated with Nivolumab based immunotherapy in 5 pts, Ipilimumab based therapy in 1 pt, Selinexor in 1 patient and Polatuzumab based therapy in 2 pts.
Median progression free survival and overall survival of non-responders was only 30.5 days and 94 days respectively. 5 out of 8 non responder pts died (4 due to disease progression and 1 due to sepsis). All three responder pts were alive and disease free at the end of study. Median follow up of our study was 108 days (range 32- 561).
Conclusions
Despite smaller sample size, our study showed dismal outcome of pts who don't respond to CART therapy, showing an unmet need for better salvage therapies in such pts. Refractory lymphoma pts with extra nodal disease involvement, higher LDH and CRP at the time of CART therapy could be negative predictors for response. Further prospective studies with larger sample size required to further validate these findings.
Figure 1 Figure 1.

Disclosures
No relevant conflicts of interest to declare.