Pyroptosis is a form of programmed cell death characterized by the cleavage of gasdermin (GSDM) family proteins that form pores in the plasma membrane, cell rupture, and the release of pro-inflammatory cytokines. In this study, we performed immunohistochemistry for cleaved GSDMD, GSDME-N-terminal, and GSDMC in two different cohorts of diffuse large B-cell lymphoma (DLBCL), and analyzed their prognostic and immune impact. The results showed frequent cleaved GSDMD (GSDMD-N-terminal) expression. Only cytoplasmic GSDMD-N-terminal expression correlated with significantly better patient survival in two cohorts. In contrast, GSDME was mainly expressed in the vascular endothelium, correlated with significantly adverse prognostic effect. Correlating with the multiplex fluorescent immunohistochemistry (mfIHC) results, we found that cytoplasmic GSDMD-N-terminal expression was associated with increased CD38+ (activated) M1 macrophages in both cohorts, cognate interactions between live DLBCL cells and activated M1 macrophages (and T cells), and lower PD-1/PD-L1 expression in the analyzed cases. In contrast, T cell pyroptosis, lymphoma cell resistance to cell death, and phagocytosis by M2 macrophages were observed in cells with nuclear GSDMD-N-terminal expression. Bulk gene expression profiling and deconvolution analysis for patients with cytoplasmic GSDMD-N-terminal expression revealed downregulation of “Don’t eat me” signaling genes, upregulation of many RNA genes, decreased frequency of “Inflammatory” lymphoma microenvironment subtype, increased abundance of prognostically favorable cell states and ecotypes, and decreased abundance of T cell exhaustion state. In summary, this study showed distinct cellular and subcellular patterns of three gasdermin proteins and their associated immune response phenotypes and prognostic effects, with implications for novel therapeutic strategies for B-cell lymphoma.

Supplemental Figure Captions

Percent LILRB1-4 positive cells in human AML PBMC. Gated on viable CD33+ cells

Abstract Introduction: Diffuse large B-cell lymphoma (DLBCL) is the most common type of malignant lymphoma. Previous studies have shown that DLBCL cells are susceptible to GPX4 (Glutathione peroxidase 4)-regulated ferroptosis, an iron-dependent type of programmed cell death characterized by increased reactive oxygen species and excessive lipid peroxidation. In addition to GPX4, FSP1 (Ferroptosis suppressor protein 1, previously known as AIFM2) is a glutathione-independent repressor of ferroptosis that has shown prognostic significance in solid tumors. In this study, we aimed to reveal the significance of GPX4 and FSP1 in DLBCL. Patients and Methods: We performed immunohistochemistry (IHC) for GPX4 and FSP1 in a large cohorts of patients with de novo DLBCL, and evaluated their cytoplasmic and nuclear expression. Prognostic analysis was performed for FSP1 and GPX4 expression in patients treated with rituximab (R)-CHOP or CHOP chemotherapy, respective of TP53 mutation status, as p53 regulates ferroptosis and TP53 mutation is associated with poorer prognosis in DLBCL. Results: FSP1 expression with a ≥10% cutoff was positive in 42.3% of DLBCL cases. Patients with TP53 mutations had a non-significant trend of higher mean FSP1 expression than those with wild-type (Wt) TP53 (P=0.11). Prognostic analysis revealed that cytoplasmic FSP1+ expression was associated with significantly poorer overall survival and progression-free survival in Wt-TP53 DLBCLs treated with R-CHOP (P=0.016 and P=0.003, respectively), and only showed non-significant unfavorable trends in TP53 mutated DLBCLs and patients treated with CHOP. In contrast, GPX4 expression did not show a significant unfavorable prognostic effect in DLBCL, and in fact, was associated with a non-significant trend of better survival. Previously we have quantified immune cell abundance and PD-1/PD-L1 expression in the tumor microenvironment of the study cohort using multiplex fluorescent IHC. Correlative analysis found that FSP1+ patients had significantly higher mean and median abundance of CD68+ cells (both M1 and M2 macrophages) and CD11c+ cells than FSP1- patients. Further analysis in Wt-TP53 and mutated TP53 subcohorts found that only in the TP53 mutated DLBCL subcohort, FSP1 expression was associated with significantly higher mean and median CD163-CD68+ (M1) and overall CD68+ macrophages, whereas in the Wt-TP53 DLBCL subcohort, FSP1 expression was associated with significantly higher median (but not mean) CD163+CD68+ (M2) macrophages and CD11c+ cells. Summary: Cytoplasmic FSP1 expression but not GPX4 had significantly adverse prognostic effect in patients with Wt-TP53 DLBCL treated with standard immunochemotherapy. Our results also suggest that in addition to ferroptosis regulation, macrophage abundance was relevant for the prognostic effects of FSP1 expression. Citation Format: Beibei Lyu, Zijun Xu-Monette, Xiaoxian X. Zhao, Eric D. Hsi, Ming Chen, Carlo Visco, Alexandar Tzankov, Karen Dybkaer, Mu-En Wang, Chang Wang, Qingyan Au, Harry Nunns, Zenggang Pan, Benjamin Parsons, Santiago Montes-Moreno, Fenghuang Zhan, Michael B. Møller, Leon Bernal-Mizrachi, Youli Zu, Shanxiang Zhang, Weina Chen, Govind Bhagat, Yong Li, KEN H. YOUNG. Expression of the ferroptosis suppressor FSP1 but not GPX4 shows significant adverse prognostic effect in diffuse large B-cell lymphoma with wild-type TP53 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 4661.

Diffuse large B-cell lymphoma (DLBCL), the most common type of lymphoma, arises from various pathogenic mechanisms including gene translocations and fusions. Detection of gene rearrangements using fluorescence in situ hybridization (FISH) is a standard practice for DLBCL diagnosis and guides treatment decisions. High-throughput chromosome conformation capture (Hi-C) DNA sequencing is a next-generation sequencing-based technology to identify genome-wide rearrangements using a single assay. In this study, Hi-C sequencing was performed using FFPE tissues from 159 patients with DLBCL, and identified 746 cancer genes at or proximal to the rearrangement breakpoints with a total of 1903 occurrences. Focusing on clinically important rearrangements, Hi-C detected 102 rearrangements of MYC, BCL2, and/or BCL6 in 92 patients and revealed the fusion partners, including 25 rearrangements missed by FISH. Causes of FISH negative results included FISH-cryptic breakpoints, complex or faint FISH signals, low percentage of FISH positivity, and issues related to tissue fixation. Moreover, in 20 patients (12.6%), Hi-C sequencing detected 22 rearrangements characteristic of other lymphoma types, including CCND1 rearrangements that could lead to reclassification as mantle cell lymphoma. Survival analysis for genome-wide rearrangements using machine learning models identified MYC, PD-L1, CCND1, BCL2, NTRK1/PRCC, RRAS, and FANCE rearrangements with significant prognostic effects in the DLBCL cohort. In conclusion, Hi-C sequencing detects gene rearrangements crucial for diagnosis in an unbiased and molecular manner and showed high sensitivity and specificity in our study. These advantages of Hi-C sequencing offer help to improve the workflow of clinical pathology laboratories, diagnostic precision, and treatment of large B-cell lymphoma.

Complete Blood Counts and Metabolic Panel for LILRB3 specific CAR adoptively transferred LILRB3 transgenic naive mice.

The t(4;14) translocation is a high-risk cytogenetic abnormality in multiple myeloma (MM) that results in overexpression of fibroblast growth factor receptor 3 (FGFR3) and enhanced MM proliferation, leading to poor prognosis. Herein, we carried out a high-throughput screen on 1855 Food and Drug Administration (FDA)-approved pharmaceuticals and identified all-trans retinoic acid (ATRA), which alone has no anti-MM effect, as a potent drug that enhances the cytotoxic effects of immunomodulatory drugs (IMiDs) in t(4;14) MM cells. Mechanistically, ATRA activates retinoic acid receptor β (RARβ), which then binds to retinoic acid response elements in the FGFR3 promoter. IMiDs enhanced nuclear translocation of histone deacetylase (HDAC)-5 and 3 by reducing HDAC5 Ser498 phosphorylation levels. RARβ, HDAC5 and HDAC3 formed a co-repressor complex that reduced chromatin accessibility and H3K27 acetylation in FGFR3 promoter, FGFR3 expression, and suppressed phosphoinositide 3-kinase/AKT signaling pathways, leading to more MM cell death. Similarly, CD2314, a selective RARβ agonist, sensitized and resensitized t(4;14) MM cells to IMiDs in vitro and in vivo. Thus, these findings underscore the therapeutic potential of ATRA and RARβ agonists in enhancing the efficacy of IMiD-based treatments for t(4;14) MM and offer a promising strategy to overcome IMiD resistance and improve outcomes in this high-risk subgroup.

Pathway analysis of LILRB3 antibody treated U937 cells.

Cholesterol metabolism reprogramming is a hallmark of cancer cells that exhibit cholesterol addiction by absorbing low-density lipoprotein (LDL) to generate cholesterol for growth. Yet the underlying mechanisms remain unclear. We began by identifying Niemann-Pick C1 (NPC1) as a key cholesterol uptake gene linked to cancer progression through clinical data analysis. Using three tumor models, we showed that NPC1 promotes tumor growth by suppressing pyroptosis. Finally, we demonstrated that the NPC1 inhibitor U18666A effectively inhibits tumor growth, supporting its therapeutic potential. Here we report that NPC1, a key player in cholesterol transport, protects cancer cells from pyroptosis across multiple cancer types. NPC1 expression was highly elevated in human cancers and negatively correlated with patient survival. NPC1 deficiency led to reduced cancer growth and enhanced sensitivity to pyroptosis under pyroptotic stress. NPC1 protects cancer cells from pyroptosis by maintaining cholesterol homeostasis and facilitating LDL-mediated cholesterol uptake, leading to enhanced geranylgeranyl pyrophosphate synthesis for cancer cell survival. Moreover, NPC1 inhibitor U18666A induced cancer cell pyroptosis and was highly therapeutic, either alone or combined with chemotherapeutics, against human hematologic and solid cancers in xenograft mouse models. This study reveals that NPC1 may be a potential therapeutic target for the treatment of human cancers.

Primary testicular (PT) diffuse large B-cell lymphoma (DLBCL) is a rare and aggressive lymphoma with distinct clinical and molecular characteristics. To identify prognostic biomarkers in PT-DLBCL, in this study we analyzed DNA and RNA samples of PT-DLBCL tumors from 206 patients using next-generation sequencing platforms and assays. Genetic alteration analysis found that multiple chromosomal copy number variations (CNVs), TP53 transcript mutations with high variant allele frequency, and MCD subtype had significantly adverse prognostic effects, whereas elevated microsatellite instability had a significantly favorable prognostic effect in PT-DLBCL. Targeted RNA-seq analysis identified a PTL gene expression signature by comparing PT-DLBCL with systemic DLBCL and revealed the heterogeneity within PT-DLBCL by unsupervised clustering, which classified PT-DLBCLs into a testicular lymphoma tumor (TLT) subtype and a microenvironment (ME) subtype. The TLT subtype featured upregulation of genes functioning in DNA damage response, DNA repair, chromatin remodeling, the cell cycle, and the nucleus, and was associated with significantly poorer patient survival and higher frequencies of MYD88 mutations, multiple CNVs, MCD subtype, bulk tumors, and elderly patients in the PT-DLBCL cohort. In contrast, the ME subtype distinctively featured upregulation of various signaling pathway genes involving the tumor microenvironment and downregulation of BTK and B-cell receptor signaling genes, and was associated with significantly better clinical outcome than the TLT subtype of PT-DLBCL independently of CNVs, MCD and MYD88 mutation and than systemic DLBCL. Moreover, genomic microRNA profiling analysis identified a PTL microRNA signature significantly differentially expressed between PT-DLBCL and systemic DLBCL patients and within the PT-DLBCL cohort, and PT-DLBCL patients with higher expression of 16 PTL microRNAs (14 are testicular tissue-specific) had significantly better survival. In summary, this study revealed the molecular heterogeneity in genetic abnormalities and expression profiles of coding genes and microRNAs within the PT-DLBCL entity, and identified significant prognostic biomarkers and PTL signatures.

Pyroptosis has emerged as a novel form of programmed cell death implicated in tumorigenesis and antitumor immunity. To gain knowledge on the role of pyroptosis in diffuse large B-cell lymphoma (DLBCL), we assessed expression of cleaved gasdermin D (GSDMD), GSDME, and GSDMC by immunohistochemistry (IHC) in a large number of DLBCL specimens, and correlated the expression to patient survival and immune biomarkers quantified by multiplex fluorescent IHC, separately in two subcohorts treated by R-CHOP or CHOP chemotherapy. We found that cleaved GSDMD cytoplasmic expression was significantly associated with better survival of patients with DLBCL, increased CD38+ M1-like macrophages (CD68+CD163- or CD11c+), and higher CD38+ percentages in both two subcohorts, as well as lower PD-L1 expression in macrophages and PD-1 expression in T cells in the R-CHOP cohort (PD-1 and PD-L1 were not evaluated in the CHOP cohort). In contrast, GSDME was mainly expressed in endothelial cells, and showed significantly unfavorable prognostic effects and associations with higher CD31+ and CD3+ cell densities in both two subcohorts. In addition, GSDME+ and high GSDMC expression were associated with higher CD38+ cell densities (including CD38+ M1-like macrophages) and percentages in the R-CHOP cohort, whereas GSDME+ was associated with increased M2-like macrophages in the CHOP cohort. Together, these prognostic and correlative results indicate that gasdermins and pyroptosis have important roles in DLBCL. R01CA233490, Duke University startup fund Tumor Immunology: Cellular Responses and Tumor Microevironment (TIME)

Abstract Background: Pyroptosis is a form of programmed cell death characterized by cleavage of gasdermin (GSDM) family proteins that form pores in the plasma membrane, cell rupture, and release of pro-inflammatory cytokines. Its pro-inflammatory potential has garnered significant research attention in recent years but has not been studied in lymphoma. Patients and Methods: We performed immunohistochemistry for cleaved GSDMD (n-terminal) in two large cohorts of diffuse large B-cell lymphoma (DLBCL) with multiplex fluorescent IHC (mfIHC) data, and analyzed for prognostic and immune impact. Results: Cleaved GSDMD was frequently expressed in DLBCL, and only the cytoplasmic (versus nuclear) form of expression correlated with significantly better patient survival in two DLBCL cohorts. To understand the expression at the single-cell level, we examined mfIHC results, which revealed that GSDMD+cells were tumor or immune cells, and varied in Ki-67, BCL2, and MYC expression. Cases with cytoplasmic cleaved GSDMD expression had higher mean and median levels of CD38+ (activated) M1 macrophages in two cohorts and lower PD-1/PD-L1 expression, as well as phenotypes of cognate interactions between live activated M1 macrophages, DLBCL cells, and T cells in spatially resolved immune landscape by mfIHC. In contrast, phagocytosis of pyroptotic lymphoma cells by M2 macrophages and cell death of T cells were observed in cases with predominantly nuclear form of cleaved GSDMD expression. Bulk gene expression profiling analysis identified a large proportion of RNA genes upregulated in DLBCLs with cytoplasmic cleaved GSDMD expression, and deconvolution analysis found decreased frequency of the “Inflammatory” lymphoma microenvironment (LME) subtype, increased frequency of cell states and ecotypes with favorable prognostic associations, and decreased frequency of T cell exhaustion states. Summary: Analysis of pyroptosis-inducing cleaved GSDMD (n-terminal) expression in a large number of DLBCL patients revealed dinstinctive cytoplasmic and nuclear expression patterns in live and pyroptotic cells associated with different prognostic and immune effects. Cytoplasmic cleaved GSDMD expression is a marker of cognate interactions between live cells (e.g., activated M1 macrophages) associated with adaptive responses and favorable prognostic effects, whereas nuclear cleaved GSDMD expression is associated with immunosuppressive mechanisms, including T cell death and phagocytosis by M2 macrophages.

Due to the slow progression of most cancers, speed of diagnosis is not of primary concern. However, the diagnosis of acute promyelocytic leukemia (APL) is unusually urgent because its hemorrhagic complications can result in death within a few days. APL is highly treatable, but the turnaround time for standard molecular testing often exceeds the window for life-saving treatment, even in advanced medical centers. The hallmark of APL is the fusion of the PML and RARα genes (t(15;17)) resulting in the expression of a growth-promoting PML-RARα fusion protein. Toward timely screening for APL, we have developed a sensitive europium-based lateral flow immunoassay for direct detection of nuclear PML-RARα fusion oncoprotein. We demonstrated a limit of detection of 11% fusion protein positive NB4 cells spiked into healthy peripheral blood mononuclear cells and an integrated filter-based sample preparation workflow showcasing its potential for clinically actionable utility in prompt APL screening. With further validation with clinical human samples this lateral flow immunoassay has the potential to enable fusion-protein based cancer diagnostics at true point-of-care.

Objective: To analyze the treatment-free remission (TFR) outcomes after discontinuation of tyrosine kinase inhibitor (TKI) in children with chronic myeloid leukemia (CML). Methods: In this retrospective cohort study, clinical data of 14 chronic phase CML children aged <18 years who had achieved stable deep molecular response (DMR) for ≥ 2 years after standardized treatment with TKI and had a strong desire to discontinue TKI at Henan Cancer Hospital from September 30, 2016 to January 30, 2022 were collected retrospectively. According to the different TFR outcomes after discontinuation of TKI, patients were divided into loss of major molecular response (MMR) group and without loss of MMR group, differences in clinical characteristics between the two groups of children were analyzed using Mann-Whitney U test and Fisher exact test. Results: Out of 14 children with TKI discontinuation, 7 were male and 7 were female. The age at diagnosis was 14.0 (4.8, 17.0) years, and the age at TKI discontinuation was 22.0 (12.5, 27.0) years. Among them, 8 children were treated with imatinib prior to TKI discontinuation and 6 children were treated with second-line substitution of the second-generation TKI nilotinib or dasatinib prior to TKI discontinuation. The follow-up time was 37.0 (27.8, 47.5) months, and 7 cases lost MMR at the time of discontinuation of 3.0 (2.0, 11.0) months. Eight children gained TFR at 6 months, 7 children gained TFR at 12 and 24 months. Amongst the 6 children who received second-generation TKI prior to TKI discontinuation, 2 children lost MMR at 3 and 11 months and 4 children gained TFR, among the 8 children who discontinued imatinib, 5 children lost MMR at the time 3.0 (2.0, 9.0) months and 3 children gained TFR. The age at diagnosis and TKI discontinuation, the time from TKI treatment to the acquisition of DMR, the duration of TKI treatment before TKI discontinuation, the duration of DMR before TKI discontinuation, and the number of children treated with second-generation TKI were not statistically different between the 7 children in the group that did not lose the MMR and the 7 children in the group that lost the MMR (all P>0.05). All the 7 children with confirmed loss of MMR immediately restarted TKI therapy, and all regained DMR after 2.0 (2.0, 11.0) months of therapy. None of the children had disease progression. After TKI discontinued, only 1 child had mild bone pain, which could be relieved by oral antipyretic analgesic drugs. Conclusions: Children with CML who have achieved a durable stable DMR for≥2 years on TKI therapy can discontinue the TKI and obtain TFR. Both the longer duration of TKI therapy, the longer duration of DMR and the use of second-generation TKI therapy before TKI discontinuation, may allow more children with CML who are expecting TKI discontinuation to have access to TFR.

Diffuse large B-cell lymphoma (DLBCL) is the most common type of non-Hodgkin lymphoma (NHL), accounting for approximately 30% of all NHL cases. DLBCL diagnosis relies on histologic examination, immunophenotyping, molecular and fluorescence in situ hybridization (FISH) analysis to differentiate it from similar NHL subtypes with overlapping morphological features, including more high-grade lymphomas like double-hit lymphoma. Because FISH is performed in a panel of single- or dual-target test format and analyzed through microscopy and manual image analysis, assessment of multiple target biomarkers can be cumbersome and expensive. As additional biomarkers for diagnosis, subtyping, prognosis, and therapeutic decision-making become available, target panels will become larger, posing additional challenges to clinical laboratories. In this study, Hi-C sequencing of FFPE samples was performed to identify all genomic rearrangements by a single sequencing analysis for an unselected DLBCL case series of 159 patients, and the results were compared to FISH for the detection of clinically important variants. Hi-C sequencing showed superior performance compared to FISH: standard FISH for DLBCL includes testing for MYC, BCL2, and BCL6. Between FISH and Hi-C, these biomarkers were detected 105 times, of which, FISH detected 80/105 (76%) and Hi-C detected 102/105 (97%). The cohort included 4 double-hit lymphomas by FISH but Hi-C sequencing detected five. Besides DLBCL diagnostic biomarkers (MYC, BCL2, BCL6), many additional biomarkers were detected by Hi-C sequencing including variants not tested by FISH because the clinical suspicion was ambiguous and the relevant FISH probes were not used, and those not tested because the biomarkers were not thought to be common and, hence, left out of the FISH panel. In total, Hi-C sequencing detected additional biomarkers in 42 (26%) cases, including (1) variants targeted by FISH (i.e. MYC, BCL2, BCL6) but negative, (2) classification biomarkers for other lymphomas (CCND1, MALT, IRF4), and (3) those not tested because the biomarkers are not common and not included in the FISH panel. These additional biomarkers were supportive of suspected diagnosis of DLBCL versus double-hit lymphoma (24 cases), prompted reconsideration of a different diagnosis that may have led to different treatments (6 cases, e.g. mantle cell lymphoma), or biomarkers such as PDL1, ALK, and ATM which have implications for targeted therapies and/or inclusion in clinical trials (5 cases). The Hi-C FFPE sequencing technology has the potential to improve the workflow of pathology labs for detection of a wide range of structural variants informing precision diagnosis and treatment for lymphomas.

Delayed immune recovery after hematopoietic stem cell (HSC) transplantation is associated with a poor clinical outcome, yet strategies to enhance lymphocyte regeneration are limited. We studied the role of unfolded protein response (ER stress) in hematopoietic regeneration within the bone marrow (BM) microenvironment. We revealed that PERK activation is a prominent feature of BM endothelium in leukemia patients and is a hallmark response in mouse BM following ionizing irradiation. Ablating endothelial Perk boosted Notch ligand DLL4 expression and promoted DLL4-dependent early HSC and B progenitor regeneration. Single-cell analysis shows that endothelial DLL4 activates NOTCH3 expressed by mesenchymal stroma cells, and that the PERK-DLL4 axis coordinates the regulation of lymphoid commitment and niche cytokine production. NOTCH3 is critical for the upregulation of IL7 following irradiation and for supporting the expansion of lymphoid progenitors in mesenchymal sphere cultures. These findings not only unveil a previously unrecognized ER stress-controlled vascular-stroma signaling mechanism in regenerative hematopoiesis but also highlight PERK blockade as a promising therapeutic strategy to improve immune recovery after myeloablative transplantation. Summary:Zou et al unravel that the adaptive ER stress response in bone marrow blood vessels restricts the post-transplant regeneration of immune progenitor cells by attenuating the expression of Notch ligand DLL4. Targeting ER stress sensor PERK can accelerate immune recovery after transplantation by enhancing DLL4-NOTCH3 signaling and IL7 cytokine production.

Introduction: Primary diffuse large B-cell lymphoma (DLBCL) of the central nervous system (CNS), traditionally referred to as primary CNS lymphoma (PCNSL), is a rare type of primary large B-cell lymphoma of immune-privileged sites with significantly poorer prognosis than systemic DLBCL. Genetic profiles of PCNSL were widely studied, whereas the tumor microenvironment has not been well characterized. Patients and Methods: A series of molecular analyses were performed using DLBCL FFPE tissues collected by the International Lymphoma Consortium. First, multiplex fluorescent immunohistochemistry (mfIHC) using antibodies for CD20, PAX5, CD3, CD4, CD8, FOXP3, CD45RO, CD68, CD56, PD-1, PD-L1, PD-L2, and CTLA-4 was performed on PCNSL tissues from 121 immunocompetent patients and de novo systemic DLBCL tissues from 405 patients. Digital quantification results for 405 patients with EBV-negative systemic DLBCL or primary testicular (PT) DLBCL have been reported previously. The preliminary mfIHC results of PCNSL will be presented. Second, mfIHC for multiple B cell biomarkers, CD3, CD4, CD8, CD68, CD163, CD11c, and CD31 were performed for 10 PCNSL validation cases, 24 PT-DLBCL and 451 systemic DLBCL tissues (unpublished). Third, RNA samples were extracted and sequenced for the targeted 1408 cancer-associated genes, successfully in 142 PCNSL cases, including 102 cases evaluated by either of these two mfIHC panels and additional 40 PCNSL cases, Results: First, in the first large mfIHC cohort, PCNSLs compared with de novo systemic nodal or extranodal DLBCL had significantly higher mean/median CD56+ cell densities whereas lower T cell densities (consistent with the immune privilege), as well as lower CD45RO+, PD-1+, and FOXP3+ percentages in T cells whereas higher CD4¯CD8¯ double-negative percentages in T cells. Prognostic analysis in the PCNSL cohort showed that high CD56+ cell densities and high CD45RO+CD8+ T cell densities were associated with significantly poorer and better patient survival, respectively, which are opposite to their prognostic effects in systemic DLBCL as previously reported. Twelve patients had very high PD-L1 expression in B cells and significantly poorer survival in the PCNSL cohort. Second, as validation, the 10 PCNSL cases in the second mfIHC study showed significantly less T cells than systemic DLBCL and PT-DLBCL cases, and low CD8 T cell densities and having low percentage of CD8 T cells adjacent to tumor cells were associated with significantly poorer survival. Immunofluorescence landscapeand spatial analysisrevealed significant differences in immune privilege between PCNSL and PT-DLBCL. Third, gene expression profiling analysis by targeted RNA-seq identified 282 significantly differentially expressed genes between PCNSL and systemic DLBCL, referred to as the PCNSL signature. Unsupervised clustering analysis divided the PCNSL cohort into two clusters, which had no significant difference in MYD88 mutation frequencies analyzed at the mRNA level. Importantly, the cluster with higher expression of many neural glial genes in the PCNSL signature had significantly poorer survival, which remained significant in multivariate analysis adjusting for clinical factors and/or treatments, two PCNSL subcohorts (as training and validation cohorts), and methotrexate-treated patients. NCAM1 (Neural Cell Adhesion Molecule 1, encoding CD56) was among the upregulated PCNSL signature genes, explaining the poorer prognosis associated with higher CD56+ cell densities in PCNSL by the mfIHC analysis. Summary: Our studies represent the largest immunophenotypic and gene expression profiling studies currently in PCNSL, a rare type of primary DLBCL of immune-privileged sites. Multiplex immunofluorescence revealed the immune landscape in PCNSL in comparison with systemic and testicular DLBCL, and identified prognostic immune biomarkers. Targeted RNA-seq identified a PCNSL gene signature enriched with neuronal-glial genes and showing significant prognostic effect in PCNSL. These novel findings in the PCNSL microenvironment warrant further studies.

Objective: To investigate the efficacy and safety of avapritinib in the treatment of molecular biologically positive core binding factor-acute myeloid leukemia (CBF-AML) with KIT mutation after allogeneic hematopoietic stem cell transplantation (allo-HSCT) . Methods: We retrospectively analyzed the clinical data of six patients with molecular biologically positive CBF-AML with KIT mutation after allo-HSCT, who were treated with avapritinib at Henan Cancer Hospital from December 2021 to March 2023, and evaluated the efficacy and safety of avapritinib. Results: After 1 month of treatment with avapritinib, the transcription level of the fusion gene decreased in six patients, and the transcription level decreased by ≥1 log in five patients. In four patients who received avapritinib for ≥3 months, the fusion gene turned negative, and the median time to turn negative was 2.0 (range: 1.0-3.0) months. Up to the end of follow-up, four patients had no recurrence. The most common adverse reaction of avapritinib was myelosuppression, including neutropenia in two cases, thrombocytopenia in two cases, and anemia in one case. The non-hematological adverse reactions were nausea in two cases, edema in one case, and memory loss in one case, all of which were grades 1-2. Conclusion: Avapritinib was effective for molecular biologically positive CBF-AML patients with KIT mutation after allo-HSCT. The main adverse reaction was myelosuppression, which could generally be tolerated.

Abstract Introduction: MYC+BCL2+ double expression (DE) is a biomarker for poor prognosis in diffuse large B-cell lymphoma (DLBCL), likely due to the cooperation between MYC and BCL2 oncoproteins in tumor cells. However, as generally MYC and BCL2 are separately assessed on two different slides by immunohistochemistry (IHC), MYC+ and BCL2+ results are from different cells. With the WHO-recommended cutoffs, ≥40% for MYC and ≥50% for BCL2 (sum < 100%), there is chance that the so-called DE comes from non-overlapping regions of the tumor (not single-cell DE). Moreover, tumor expression scores based on morphology assessment often vary among pathologists. In this study, we performed fluorescent multiplex IHC (fmIHC) using a MultiOmyxTM immunofluorescence platform (NeoGenomics Laboratories, Inc.) to determine single-cell MYC and BCL2 co-expression for prognostic analysis in DLBCL. Patients and Methods: Co-expression of MYC, BCL2, and 11 immunophenotypic markers by fmIHC was digitally quantified for 547 patients with DLBCL. Percentage of cells with MYC/BCL2 double or single expression was calculated for various cell types. Prognostic analysis was performed for de novo DLBCL cases, including 108 patients treated CHOP chemotherapy, and 356 patients treated with rituximab (R)-CHOP. Results: First, although MYC and BCL2 were expressed in multiple cell types, the vast majority (>90%) of MYC+BCL2+ DE cells were lymphoma cells. Frequencies of MYC and BCL2 co-expression were consistent with random distribution of independent MYC/BCL2 expression in positive cases. The activated B-cell-like subtype compared with the germinal center B-cell-like subtype had a significantly higher mean percentage of MYC+BCL2+ DE, but not single BCL2 or MYC expression, in PAX5+ cells. Second, in both the R-CHOP and CHOP cohorts, high percentages of DE in PAX5+ cells and in all DAPI+ cells were associated with significantly poorer survival of DLBCL patients. Very high percentage of single BCL2 expression in PAX5+ cells was also associated with poorer survival, however, only in a small number of patients in both cohorts. Only in the R-CHOP cohort, high single MYC expression in PAX5+ cells (in a significant proportion of the cohort) was associated with significantly poorer overall survival. In the R-CHOP cohort, eight cases had MYC/BCL2 double hit by FISH, including 3 cases with MYC/IGH fusions (DE) and 5 cases with MYC/non-IGH rearrangements (only one DE). The exclusion of these double hit cases did not impact the significance of DE and single MYC+ expression. Summary: True MYC+BCL2+ double protein expression at the single cell level is predominantly in lymphoma cells, and associated with significantly poor survival of DLBCL patients. Our results suggest high cutoffs for common MYC/BCL2 IHC to identify true double expressor lymphoma. Citation Format: Zijun Yidan Xu-Monette, Yong Li, Qingyan Au, Harry Nunns, Wenyu Shi, Alexandar Tzankov, Carlo Visco, Govind Bhagat, Eric Hsi, Xiaoxian X. Zhao, Karen Dybkaer, April Chiu, Wayne Tam, Youli Zu, Fredrick B. Hagemeister, Andrew Song, Michele Pellegrino, Heounjeong Go, Maurilio Ponzoni, Andrés Ferreri, Michael B. Møller, Benjamin Parsons, J. Han van Krieken, Miguel A. Piris, Jane N. Winter, Mingzhi Zhang, Bing Xu, Ken H. Young. Single-cell double expression of MYC and BCL2 proteins by fluorescent multiplex IHC is mainly in lymphoma cells with significant prognostic impact in large B-cell lymphoma while suggesting high cutoffs for routine IHC [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6418.