The INTeRCePT 2 study aims to develop a predictive assay to determine which patients with B cell lymphoma are most likely to respond to CAR T cell therapy. This assay combines five components for longitudinal profiling of each patient. The goal of the trial is that the assay can be completed (feasibility). This comprehensive assay integrates five key components including circulating tumor DNA (CAPPseq), inflammation markers from peripheral blood tests (InflaMIX), PET CT imaging parameters, immune cell profiles (flow cytometry), and performance status (ECOG). Ultimately, this tool could improve treatment selection, and guide more personalized therapy decisions for lymphoma patients receiving CAR T cells.

Anti-CD19 CAR T-cell therapy is the new standard therapy for patients with relapsed/refractory aggressive B-cell lymphoma and transformed cure rates. The majority of patients fail treatment within the first 90 days. These results indicate a high medical need to optimize therapy e.g. by intensification for patients with high-risk of relapse after CD19-redirected CAR T cell therapy. INTeRCePT 2.0 is a feasibility study with application of a dynamic individualized risk profiling for prediction and early detection of high-risk constellation of patients post anti-CD19 CAR T-cell therapy.

We aim to develop tools to predict therapy failure earlier to provide appropriate therapy early post CAR T application in future studies.

Primary objective: Complete risk profiling (INTeRCePT assay) post-CAR T infusion (Arm A and B)(feasibility) Primary endpoint: Rate of complete INTeRCePT assay risk profiling post-CAR T infusion (Arm A and B) Co-primary objective: Complete risk profiling (INTeRCePT assay) by day 38 post-CAR T infusion (Arm A) Co-primary endpoint: Rate of complete INTeRCePT assay risk profiling by day 38 post-CAR T infusion (Arm A)

The primary variable of interest (primary endpoint and co-primary endpoint) of the study is the rate of complete INTeRCePT assay risk profiling by 38 days post-CAR-T cell infusion. These variables were selected as they directly measure the feasibility and timeliness of obtaining a full molecular risk profile within the critical time window post-infusion. This early risk assessment is key for future intervention in the window of opportunity for curation (low lymphoma load, CAR T cells still present in high numbers). In this study, clinical decisions are not influenced by the INTeRCePT assay results, but the study tests if the assay is completed and thus provides the basis for future (interventional) trials.

The secondary objectives will evaluate the predictive value of the INTeRCePT assay. The key secondary endpoint will be the rate of accurate prediction of complete response (CR vs. no CR) by 3 months post-CAR T-cell infusion. CR is defined as complete remission 3 months post CAR T cell therapy without the need for additional cancer-directed treatment. The accuracy of the INTeRCePT assay will be measured based on true positive and true negative rates, with a threshold of at least 80% predictive accuracy.

In addition, we will evaluate sensitivity and specificity of the INTeRCePT assay, as well as PFS, OS, DOR and response rates at several time points up to 12 months post CAR T cell infusion.

Patients with complete metabolic response (Deauville Score 1 and 2 in PET-CT month 1) have a high probability for CR at month 3, while patients with highly active lesions (Deauville Score 5 in PET-CT month 1) have a high risk for CAR T failure. We expect that patients with Deauville Score 3 and 4 could mostly benefit from our combinatorial risk profiling, as this group has a relevant chance for both curation and failure. In this setting, information based on tumor load dynamics, highly sensitive ctDNA measurement and in addition the immune fitness might play a major role for personalized risk stratification. Furthermore, we hypothesize that the INTeRCePT assay will allow for earlier risk prediction, even prior to CAR T cell infusion or apheresis. Here we expect the fitness and function of immune cells - the source for CAR T cells - an important measurement for risk prediction

We intend to assess symptoms of anxiety and depression along with cancer-related quality of life. These psychosocial factors are not routinely evaluated as part of standard CAR T cell therapy protocols, despite their potential impact on patient well-being and recovery. By addressing this gap, we aim to gain a more comprehensive understanding of the patient experience. Insights from these assessments may help identify areas where additional support is needed and could inform the development of more integrated care approaches in the future.

Exploratory objectives: To improve the risk prediction for lymphoma patients treated with CAR T cells in the future, additional parameters will be evaluated in an exploratory setting.

Methods: INTeRCePT 2.0 is a single-center study to prove the feasibility and prognostic value of the INTeRCePT assay, which is a combinatorial, in-depth analysis of measurable residual disease (MRD), inflammation status and immune environment "fitness". The INTeRCePT assay includes the following five components for longitudinal and dynamic measurement in-house from the timepoint of relapse until day28 post-CAR T infusion:

1. Circulating tumor DNA (ctDNA in hGE/ml) analysis from peripheral blood is conducted through cancer personalized profiling by deep sequencing (CAPPseq). The ctDNA analysis pipeline covers 8 time points of measurement.
2. Low-dimensional single-cell flow cytometry will assess the immune profile (CAR T cells and non-CAR immune cells). scCytometry measurements are performed at 5 time points.
3. PET-CT/-MRI assessment with Deauville Score, total metabolic tumor volume (TMTV) and total lesion glycolysis (TLG). PET-CT is performed at 3 time points.
4. Performance status ECOG is assessed at 3 time points (relapse/progress, lymphodepletion, month 1 post CAR T infusion).
5. InflaMix model is based on 14 blood parameters, which are measured in clinical routine. These parameters capture the inflammatory state of the patients and will documented at one time point

The study population includes patients with lymphoid malignancies receiving anti-CD19 CAR T-cell therapy. 50 patients in total will be enrolled in the study.

Summary: Administration of an appropriate therapy early post-CAR T application in identified high-risk patients is crucial to improve patient outcome. Within the INTeRCePT 2.0 trial, we establish feasibility of the comprehensive personalized risk profiling by the INTeRCePT assay.

Inclusion Criteria:

• Written informed consent before registration and prior to any trial specific procedures
• Participants ≥ 18 years of age
• Diagnosis of relapse/refractory B-cell lymphoma according to WHO 2022 classification
• Measurable disease per response criteria specific to the disease e.g. per Lugano 2014 criteria
• Patients planned for CD19-redirected CAR T cell therapy according to clinical standard of care
• Patients who are willing to donate peripheral blood and biopsy material at indicated clinical visits

Exclusion Criteria:

• Any condition, which precludes initiation of CD19-redirected CAR T cell therapy (e.g. breast feeding, pregnancy, infections, etc.) as judged by the treating physician
• Any coexisting medical or psychological condition that would preclude participation in the required study procedures, as judged by the treating physician
• Unwillingness or inability to comply with the protocol

The study population includes patients with lymphoid malignancies receiving anti-CD19 CAR T-cell therapy. This population is at high risk for disease progression. 50 patients in total will be enrolled in the study. The study does not include an additional control group but the risk analysis in arm B will be performed with blinding to the patient outcome. We expect to have a balanced sex proportion within our trial.