Assessing CAR T-cell therapy response using genome-wide sequencing of cell-free DNA in patients with B-cell lymphomas

Abstract Background Chimeric antigen receptor (CAR) T cell therapy has had great success in treating patients with relapsed or refractory B cell malignancies, with CD19-targeting therapies now approved in many countries. However, a subset of patients fails to respond or relapse after CD19 CAR T cell therapy, in part due to antigen loss, which has prompted the search for alternative antigen targets. CD22 is another antigen found on the surface of B cells. CARs targeting CD22 alone or in combination with other antigens have been investigated in several pre-clinical and clinical trials. Given the heterogeneity and small size of CAR T cell therapy clinical trials, systematic reviews are needed to evaluate their efficacy and safety. Here, we propose a systematic review of CAR T cell therapies targeting CD22, alone or in combination with other antigen targets, in B cell malignancies. Methods We will perform a systematic search of EMBASE, MEDLINE, Web of Science, Cochrane Register of Controlled Trials, clinicaltrials.gov, and the International Clinical Trials Registry Platform. Ongoing and completed clinical trials will be identified and cataloged. Interventional studies investigating CD22 CAR T cells, including various multi-antigen targeting approaches, in patients with relapsed or refractory B cell malignancies will be eligible for inclusion. Only full-text articles, conference abstracts, letters, and case reports will be considered. Our primary outcome will be a complete response, defined as absence of detectable cancer. Secondary outcomes will include adverse events, overall response, minimal residual disease, and relapse, among others. Quality assessment will be performed using a modified Institute of Health Economics tool designed for interventional single-arm studies. We will report a narrative synthesis of clinical studies, presented in tabular format. If appropriate, a meta-analysis will be performed using a random effects model to synthesize results. Discussion The results of the proposed review will help inform clinicians, patients, and other stakeholders of the risks and benefits of CD22 CAR T cell therapies. It will identify gaps or inconsistencies in outcome reporting and help to guide future clinical trials investigating CAR T cells. Systematic review registration PROSPERO registration number: CRD42020193027

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Influence of TP53 Mutation on Survival of Diffuse Large B-Cell Lymphoma in the CAR T-Cell Era

Cancers ◽

10.3390/cancers13225592 ◽

2021 ◽

Vol 13 (22) ◽

pp. 5592

Author(s):

Edit Porpaczy ◽

Philipp Wohlfarth ◽

Oliver Königsbrügge ◽

Werner Rabitsch ◽

Cathrin Skrabs ◽

...

Keyword(s):

T Cell ◽

Cell Therapy ◽

B Cell ◽

Tp53 Mutation ◽

Cell Lymphoma ◽

B Cell Lymphoma ◽

T Cell Therapy ◽

Car T Cell ◽

Car T Cell Therapy ◽

Car T

Refractory/relapsed diffuse large B-cell lymphoma (DLBCL) is associated with poor outcome. The clinical behavior and genetic landscape of DLBCL is heterogeneous and still not fully understood. TP53 mutations in DLBCL have been identified as markers of poor prognosis and are often associated with therapeutic resistance. Chimeric antigen receptor T-cell therapy is an innovative therapeutic concept and represents a game-changing therapeutic option by supporting the patient’s own immune system to kill the tumor cells. We investigated the impact of TP53 mutations on the overall survival of refractory/relapsed DLBCL patients treated with comparable numbers of therapy lines. The minimum number of therapy lines was 2 (median 4), including either anti-CD19 CAR T-cell therapy or conventional salvage therapy. A total of 170 patients with DLBCL and high-grade B-cell lymphoma with MYC, BCL2, and/or BCL6 rearrangements (DHL/THL), diagnosed and treated in our hospital between 2000 and 2021, were included. Twenty-nine of them received CAR T-cell therapy. TP53 mutations were found in 10/29 (35%) and 31/141 (22%) of patients in the CAR T-cell and conventional groups, respectively. Among the 141 patients not treated with CAR T cells, TP53 mutation was an independent prognostic factor for overall survival (OS) (median 12 months with TP53 vs. not reached without TP53 mutation, p < 0.005), but in the CAR T cell treated group, this significance could not be shown (median OS 30 vs. 120 months, p = 0.263). The findings from this monocentric retrospective study indicate that TP53 mutation status does not seem to affect outcomes in DLBCL patients treated with CAR T-cell therapy. Detailed evaluation in large cohorts is warranted.

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Fludarabine Exposure Predicts Outcome after CD19 CAR T Cell Therapy in Children and Young Adults with Acute Leukemia; An Exploratory, Observational Study

Blood ◽

10.1182/blood-2021-146450 ◽

2021 ◽

Vol 138 (Supplement 1) ◽

pp. 3871-3871

Author(s):

Linde Dekker ◽

Friso Calkoen ◽

Yilin Jiang ◽

Hilly Blok ◽

Maike Spoon ◽

...

Keyword(s):

T Cell ◽

Clinical Outcome ◽

Cell Therapy ◽

B Cell ◽

T Cell Therapy ◽

Free Survival ◽

Cell Numbers ◽

Car T Cell ◽

Car T Cell Therapy ◽

Car T

Abstract The addition of fludarabine to cyclophosphamide as lymphodepleting regimen prior to adoptive transfer of CD19 chimeric antigen receptor (CAR) T cells significantly improves CAR T cell expansion and correlates with longer B cell aplasia and a decreased probability of developing a CD19+ relapse (Gardner, 2017). Dosing of fludarabine is currently based on body surface area. We previously showed that this leads to a highly variable plasma exposure that correlates with clinical outcome after allogeneic hematopoietic cell transplantation (Langenhorst, 2019). We therefore hypothesized that optimal exposure of fludarabine might be of clinical importance in the CD19 CAR T setting. An observational cohort analysis was conducted with data from 26 consecutive patients receiving tisagenlecleucel as treatment for refractory/relapsed B cell acute lymphoblastic leukemia (B-ALL; table 1). Prior to CAR T cell infusion, patients received fludarabine on 4 consecutive days at a daily dosage of 30 mg/m 2 and cyclophosphamide on 2 consecutive days at a daily dosage of 500 mg/m 2. Fludarabine concentrations were measured longitudinally after fludarabine infusion using a liquid chromatography mass spectrometry method. The total exposure (Area Under the Curve (AUC 0−∞)) was subsequently determined using a fludarabine population pharmacokinetic model (Langenhorst, 2019). The study was performed in accordance with the Declaration of Helsinki. The primary outcome parameter was leukemia free survival, defined as the time between CAR19 T cell infusion and the moment of measurable leukemic blasts (>5% or >0.01% by two subsequent measurements). The effect of fludarabine on leukemia free survival and the secondary outcome measures CD19+ relapse and B cell aplasia were explored using martingale residuals and further identified by fitting univariable Cox Proportional Hazards models. In addition, Kaplan Meier and cumulative incidence curves were plotted and compared with log-rank tests. To compare CAR T cell numbers over time in peripheral blood, the AUCs were computed and compared between exposure groups with the Mann-Whitney test. Analyses were performed using R4.03 with packages pknca, survival and survminer. The fludarabine AUC 0−∞ was highly variable, resulting in a large range of 8.7-21.8 mg*h/L. Exposure of fludarabine was shown to be a predictor for leukemia free survival, B cell aplasia, and CD19+ relapse following CAR T cell infusion. Minimal event probability was observed at a cumulative fludarabine exposure ≥14 mg*h/L and underexposure was therefore defined as an AUC 0−∞ <14 mg*h/L. In the underexposed group, leukemia free survival was lower (p<0.001; Figure 1A) and the occurrence of CD19+ relapse was higher (p<0.0001; figure 1B) compared to the group with an AUC 0−∞ ≥14 mg*h/L. Furthermore, the duration of B cell aplasia was shorter (p=0.009) and the AUCs of CAR T cell numbers lower (p=0.03) in the underexposed group. No significant differences in baseline characteristics were present between the two exposure groups. To our knowledge, this is the first study describing the effect of fludarabine exposure on outcome in a cohort of paediatric and young adults receiving CD19 CAR T cell therapy as treatment for B-ALL. These preliminary results suggest that optimizing fludarabine exposure may have a relevant impact on leukemia free survival following CAR T cell therapy. However, it should be noted that multivariate regression models are needed to show consistency of the relationship between fludarabine exposure and outcome. The limited number of patients did not allow for inclusion of potential covariates that may influence clinical outcome into the analysis. Therefore, our results need to be confirmed in a larger cohort. In conclusion, clinical outcome in patients receiving CAR19 T cell therapy might be improved by the optimization of fludarabine exposure in the lymphodepleting regimen. LD and FC contributed equally to this study. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

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