<figure><img src="image_1.png" /></figure>

**Results:** The non-GC subtype was detected in 19 (61%) out of 31 DLBCL pts and in 7 (41%) out of 17 evaluable PCNSL pts. Both DLBCL as well as LBCL-IPS showed a significantly higher α-diversity (p < 0.005), as well as a significant shift in β-diversity (p < 0.05) of their oralMB compared to CON (Figure 1). This shift was associated with an increased relative abundance of microbes from the order Fusobacteriales and family Lachnospiraceae in DLBCL and from the order Fusobacteriales and family Prevotellaceae in LBCL-IPS. GutMB of DLBCL had significantly lower α-diversity (p < 0.05) compared to CON whereas LBCL-IPS showed only borderline decrease (p = 0.06). In addition, only gutMB of LBCL-IPS showed significant shift in β-diversity (p < 0.05) vs. CON. GutMB of DLBCL was associated with increased relative abundance of pathobionts from genera *Escherichia*/*Shigella*, *Ruminococcus gnavus* group and *Bilophila*, and LBCL-IPS microbiota had higher abundance of genera *Akkermansia* and *Veillonella*.

**Conclusions:** Both lymphoma groups—diffuse large B-cell lymphoma as well as large B-cell lymphoma of immune-privileged sites—are characterized by unique microbiota composition. Both the oral and fecal microbiota of lymphoma patients differ from those of healthy individuals. The follow-up studies are focused on microbiota composition and therapy outcome.

**The research was funded by:** The study is supported by the Co operation Program, research area “Oncology and Haematology” and NU20-03-00253 and NU22-03-00370.

**Keywords:** Aggressive B-cell non-Hodgkin lymphoma, Diagnostic and Prognostic Biomarkers, Tumor Biology and Heterogeneity

**No conflicts of interests pertinent to the abstract.**

197 | TAYLORING LYMPHOMA THERAPY WITH IMMUNE ESCAPE SIGNATURES FROM 3D AVATARS OF B-CELL NHL

F. Gava¹, C. Faria², P. Gravelle¹, J. Garcia-Valero³, C. Quelen¹,
N. Serrat³, N. Gower⁴, F. Morschhauser⁴, J. Fournie¹, F. Bouquet⁵,
C. Fonseca⁶, S. Herter⁶, L. Codarri⁶, R. McCord⁷, E. Chiang⁷,
C. Laurent⁸, P. Perez-Galan³, L. Ysebaert⁹, C. Bezombes¹

¹Cancer Research Center of Toulouse, INSERMU1037, Toulouse, France,
²Bernhard Gentner Laboratory, Agora Research Center, Oncology
Department UNIL-CHUV, Lausanne, Switzerland, ³IDIBAPS, Barcelona,
Spain, ⁴CHU Lille, Department of Hematology, Lille, France, ⁵F.Hoffmann-
La Roche, Basel, Switzerland, ⁶Roche Innovation Center Zürich, Roche,
Roche Pharma Research and Early Development, Schlieren, Switzerland,
⁷Genentech, San Francisco, California, USA, ⁸IUCT-Oncopole, Department
of Pathology, Toulouse, France, ⁹IUCT-Oncopole, Department of
Hematology, Toulouse, France

F. Gava and C. Faria are co-first authors
L. Ysebaert and C. Bezombes are co-corresponding authors

Relapsed/refractory B-cell NHLs are made up with a heterogeneous array of incurable diseases, whose outcomes in the rituximab era are unclear, despite patients benefit from new therapeutic strategies. In most cases, the choice of therapy is based on age, comorbidities, and duration of last response to immuno-chemotherapy. We lack predicting factors able to dictate this choice on a patient-per-patient basis, as exemplified by immune checkpoint blockade since we often do not understand why these drugs fail or succeed in our patients. One strategy to improve the rate of success of new cancer drugs prioritization in the clinic, would be to more closely align the cellular models used in our translational scientific projects to patients' tumors.

Here, we present a new preclinical follicular lymphoma (FL) 3D model called Patient-Derived Lymphoma Spheroid (FL-PDLS) that recapitulates the FL pathogenesis and the B cells-immune tumor microenvironment crosstalk. We established a workflow allowing their full characterization and present evidences that PDLS, which are mainly composed of tumor B cells and autologous T cells, exhibit an exhausted immune phenotype typical of FL lymph node, including a medium to high expression of several ICP TIGIT, PD1, TIM3 or LAG3 that can be targeted. These 3D avatars constitute a platform for high-throughput screening of therapeutic antibodies. Among functional assays available, we can assess the ability of lymphomatous cells to grow in 3D and ability of T cells to infiltrate/kill 3D autologous models and/or 3D cell lines models of NHL.

Thus, in the era of personalized medicine FL-PDLS appear a promising preclinical model to predict patient response and discover new therapeutic target. This system can evolve towards full FL-TME reconstituted organoids and therefore become powerful therapeutic biomaterials that combine therapy with diagnosis necessary for individualized therapies for patients.

The research was funded by: This research collaboration was supported through the imCORE network on behalf of F.Hoffmann-La Roche.

**Keywords:** Aggressive B-cell non-Hodgkin lymphoma, Immuno-therapy, Risk Models

**Conflicts of interests pertinent to the abstract.**

**F. Morschhauser**

Consultant or advisory role: Roche, Gilead, Genmab, Novartis, Abbvie,
Honoraria: Chugai (scientific lectures)

**F. Bouquet**

Employment or leadership position: Roche employee

**C. Fonseca**

Employment or leadership position: Roche employee
<figure><img src="image_2.png" /></figure>

S. Herter

Employment or leadership position: Roche employee

Stock ownership: Roche

L. Codarri

Employment or leadership position: Roche employee

R. McCord

Employment or leadership position: Genentech employee

E. Chiang

Employment or leadership position: Genentech employee

C. Laurent

Educational grants: Janssen

¹CHU Lille, Department of Hematology, Lille, France, ²Cancer Research Center of Toulouse, INSERMU1037, Tlouse, France, ³Bernhard Gentner Laboratory, Agora Research Center, Oncology Department UNIL-CHUV, Lausanne, Switzerland, ⁴IDIBAPS, Barcelona, Spain, ⁵F.Hoffmann-La Roche, Basel, Switzerland, ⁶Roche Innovation Center Zürich, Roche, Roche Pharma Research and Early Development, Schlieren, Switzerland, ⁷Genentech, San Francisco, California, USA, ⁸IUCT-Oncopole, Department of Hematology, Toulouse, France, ⁹IUCT-Oncopole, Department of Pathology, Toulouse, France

Despite therapeutic advances, follicular lymphoma (FL) remains an incurable disease. In addition to tumour-specific genomic alterations, the tumour microenvironment plays an essential role in the progression of the disease by participating in immuno-escape mechanisms. Among them, the PD-1/PDL1 axis has been widely studied but the efficacy of anti-PD-1 remains limited in FL suggesting additional immune escape mechanisms such as LAG-3. In order to decipher this issue, we tested the efficacy of a bispecific antibody targeting both PD1 and LAG-3 ICPs in a 3D model of FL co-cultured with PD-1/LAG-3 expressing γδT cells.

Therefore, we studied γαμμαδελταΤ cells infiltration and measured their activation as well as tumour B cell depletion by flow cytometry and high throughput 2D/3D analyses. Our results showed that aPD-1xLAG-3 bispecific antibody enhances CD20-TCB efficacy by increasing γδT cells infiltration into 3D model and their activation as attested by an increase of Granzyme B and IFNγαμμα secretion. Consequently, a decrease of 3D area correlated with a potent B cell depletion was observed after combination treatment. Finally, we observed that percent of PD-1+/LAG3+ γαμμαδελταΤ cells negatively correlates with drug efficacy. 3D cell cultures from FL biopsies

**198** | STUDY OF THE EFFICACY OF NOVEL BISPECIFIC ANTIBODIES TARGETING IMMUNE CHECKPOINTS IN A 3D MODEL OF B NON-HODGKIN LYMPHOMA

N. Gower¹, F. Gava², L. Rimailho², C. Faria³, P. Gravelle², P. Perez-Galan⁴, N. Serrat⁴, F. Bouquet⁵, C. Fonseca⁶, S. Herter⁶, L. Codarri⁶, R. McCord⁷, E. Chiang⁷, F. Morschhauser¹, L. Ysebaert⁸, C. Laurent⁹, C. Bezombes²

N. Gower and F. Gava are co-first authors

C. Laurent and C. Bezombes are co-last authors and corresponding authors