Comparative performance of scFv-based anti-BCMA CAR formats for improved T cell therapy in multiple myeloma

In multiple myeloma (MM), B cell maturation antigen (BCMA)-directed CAR T cells have emerged as a novel therapy with potential for long-term disease control. Anti-BCMA CAR T cells with a CD8-based transmembrane (TM) and CD137 (41BB) as intracellular costimulatory domain are in routine clinical use. As the CAR construct architecture can differentially impact performance and efficacy, the optimal construction of a BCMA-targeting CAR remains to be elucidated. Here, we hypothesized that varying the constituents of the CAR structure known to impact performance could shed light on how to improve established anti-BCMA CAR constructs. CD8TM.41BBIC-based anti-BCMA CAR vectors with either a long linker or a short linker between the light and heavy scFv chain, CD28TM.41BBIC-based and CD28TM.CD28IC-based anti-BCMA CAR vector systems were used in primary human T cells. MM cell lines were used as target cells. The short linker anti-BCMA CAR demonstrated higher cytokine production, whereas in vitro cytotoxicity, T cell differentiation upon activation and proliferation were superior for the CD28TM.CD28IC-based CAR. While CD28TM.CD28IC-based CAR T cells killed MM cells faster, the persistence of 41BBIC-based constructs was superior in vivo. While CD28 and 41BB costimulation come with different in vitro and in vivo advantages, this did not translate into a superior outcome for either tested model. In conclusion, this study showcases the need to study the influence of different CAR architectures based on an identical scFv individually. It indicates that current scFv-based anti-BCMA CAR with clinical utility may already be at their functional optimum regarding the known structural variations of the scFv linker.

Multicenter development of a PET-based risk assessment tool for product-specific outcome prediction in large B-cell lymphoma patients undergoing CAR T-cell therapy

PURPOSE

The emergence of chimeric antigen receptor (CAR) T-cell therapy fundamentally changed the management of individuals with relapsed and refractory large B-cell lymphoma (LBCL). However, real-world data have shown divergent outcomes for the approved products. The present study therefore set out to evaluate potential risk factors in a larger cohort.

METHODS

Our analysis set included 88 patients, treated in four German university hospitals and one Italian center, who had undergone 2-[18F]fluoro-2-deoxy-D-glucose positron emission tomography (PET) before CAR T-cell therapy with tisagenlecleucel or axicabtagene ciloleucel. We first determined the predictive value of conventional risk factors, treatment lines, and response to bridging therapy for progression-free survival (PFS) through forward selection based on Cox regression. In a second step, the additive potential of two common PET parameters was assessed. Their optimal dichotomizing thresholds were calculated individually for each CAR T-cell product.

RESULTS

Extra-nodal involvement emerged as the most relevant of the conventional tumor and patient characteristics. Moreover, we found that inclusion of metabolic tumor volume (MTV) further improves outcome prediction. The hazard ratio for a PFS event was 1.68 per unit increase of our proposed risk score (95% confidence interval [1.20, 2.35], P = 0.003), which comprised both extra-nodal disease and lymphoma burden. While the most suitable MTV cut-off among patients receiving tisagenlecleucel was 11 mL, a markedly higher threshold of 259 mL showed optimal predictive performance in those undergoing axicabtagene ciloleucel treatment.

CONCLUSION

Our analysis demonstrates that the presence of more than one extra-nodal lesion and higher MTV in LBCL are associated with inferior outcome after CAR T-cell treatment. Based on an assessment tool including these two factors, patients can be assigned to one of three risk groups. Importantly, as shown by our study, metabolic tumor burden might facilitate CAR T-cell product selection and reflect the individual need for bridging therapy.

Artificial intelligence-based polyp size measurement in gastrointestinal endoscopy using the auxiliary waterjet as a reference

BACKGROUND

Measurement of colorectal polyp size during endoscopy is mainly performed visually. In this work, we propose a novel polyp size measurement system (Poseidon) based on artificial intelligence (AI) using the auxiliary waterjet as a measurement reference.

METHODS

Visual estimation, biopsy forceps-based estimation, and Poseidon were compared using a computed tomography colonography-based silicone model with 28 polyps of defined sizes. Four experienced gastroenterologists estimated polyp sizes visually and with biopsy forceps. Furthermore, the gastroenterologists recorded images of each polyp with the waterjet in proximity for the application of Poseidon. Additionally, Poseidon's measurements of 29 colorectal polyps during routine clinical practice were compared with visual estimates.

RESULTS

In the silicone model, visual estimation had the largest median percentage error of 25.1 % (95 %CI 19.1 %-30.4 %), followed by biopsy forceps-based estimation: median 20.0 % (95 %CI 14.4 %-25.6 %). Poseidon gave a significantly lower median percentage error of 7.4 % (95 %CI 5.0 %-9.4 %) compared with other methods. During routine colonoscopies, Poseidon presented a significantly lower median percentage error (7.7 %, 95 %CI 6.1 %-9.3 %) than visual estimation (22.1 %, 95 %CI 15.1 %-26.9 %).

CONCLUSION

In this work, we present a novel AI-based method for measuring colorectal polyp size with significantly higher accuracy than other common sizing methods.

Functional connectivity MRI provides an imaging correlate for chimeric antigen receptor T-cell-associated neurotoxicity

Background

Treatment of hematological malignancies with chimeric antigen receptor modified T cells (CART) is highly efficient, but often limited by an immune effector cell-associated neurotoxicity syndrome (ICANS). As conventional MRI is often unremarkable during ICANS, we aimed to examine whether resting-state functional MRI (rsfMRI) is suitable to depict and quantify brain network alterations underlying ICANS in the individual patient.

Methods

The dysconnectivity index (DCI) based on rsfMRI was longitudinally assessed in systemic lymphoma patients and 1 melanoma patient during ICANS and before or after clinical resolution of ICANS.

Results

Seven lymphoma patients and 1 melanoma patient (19-77 years; 2 female) were included. DCI was significantly increased during ICANS with normalization after recovery (P = .0039). Higher ICANS grades were significantly correlated with increased DCI scores (r = 0.7807; P = .0222). DCI increase was most prominent in the inferior frontal gyrus and the frontal operculum (ie, Broca's area) and in the posterior parts of the superior temporal gyrus and the temporoparietal junction (ie, Wernicke's area) of the language-dominant hemisphere, thus reflecting the major clinical symptoms of nonfluent dysphasia and dyspraxia.

Conclusions

RsfMRI-based DCI might be suitable to directly quantify the severity of ICANS in individual patients undergoing CAR T-transfusion. Besides ICANS, DCI seems a promising diagnostic tool to quantify functional brain network alterations during encephalopathies of different etiologies, in general.