Bone Marrow Infiltration Research Articles

Immune and Genome Profiling of Myeloma Patients Treated with Sequential Immunotherapies Reveal Differential Non-Overlapping Mechanisms of Resistance

Chimeric antigen receptor T cells (CAR T) or bispecific T cell engagers (TCE) targeting multiple myeloma (MM) antigens result in deep responses in relapsed patients. Nevertheless, resistance invariably emerges requiring salvage treatments. Sequential therapies with CAR T or TCE, in patients with or without prior anti-BCMA therapy exposure, reported durable responses. However the genomic and molecular determinants of response to sequential immunotherapies are poorly defined. To define the molecular determinants of response to sequential immunotherapies we identified patients treated with more than one anti-BCMA or -GPRC5D (n=8) regimens. Bone marrow (BM) and peripheral blood (PB) mononuclear cells from these patients were collected prior to each therapy and at the time of progression. Sorted CD138+ cells were subjected to whole genome sequencing (WGS) or single cell CNV (scCNV) and single cell RNA (scRNA) analysis. CD3+ T cells were subjected to CITEseq and functional in vitro cytotoxicity assays. Patient 1 received anti-BCMA CAR T (Ide-cel) with VGPR lasting 7 months (mos) (Figure 1). He subsequently received elranatamab with no response. CITEseq profiling of T cells at progression post CAR T did not reveal expansion of exhausted cytotoxic or regulatory T cells. However, WGS and scCNV of MM cells identified biallelic TNFRSF17 deletion consistent with antigenic escape as cause of resistance. Patient 2 received Ide-cel (DOR = 3.5 mos) followed by elranatamab with no response. CD138+ MM cells retained BCMA expression and in vitro studies with in-house manufactured anti-BCMA CAR T efficiently eliminated his MM cells. Profiling of T cells showed terminal T cells exhaustion (CD45RA +, TOX +, TIGIT +, PDCD1 + and LAG3 +). In contrast to recipients of CAR T, antigenic loss was commonly observed post TCE therapy. Patient 3 received 3 sequential therapies with Ide-cel (DOR = 3 mos), teclistamab (DOR = 6 mos), and then talquetamab with daratumumab with an ongoing response of 11 mos. While T cell exhaustion was not observed, functional loss of BCMA on MM cells was detected post teclistamab, with 2 coexisting clones harboring TNFRSF17 extracellular domain mutations (p.Pro34del, or p.Ser30del) that abrogated teclistamab binding. Similarly in patient 4 progressing on elranatamab (DOR = 21 mos), there was no evidence of T cell exhaustion but rather acquired BCMA mutation (p.Pro34del) in MM cells. Consistent with fit T cells profile, he has an ongoing response (13+ mos) to talquetamab and daratumumab in his next line of therapy. Patient 5 with penta-refractory disease and high disease burden (> 90% BM infiltration) had no response to elranatamab, however achieved an ongoing sCR (DOR = 30 mos) with talquetamab, daratumumab and pomalidomide (Tal-DP). PB T cells did not show exhaustion at the time of progression on elranatamab. A similar pattern was observed in patient 6 with high disease burden and no response to teclistamab but achieved lasting VGPR to Tal-DP (DOR=24 mos) in the next line followed by an acquired biallelic loss of GPRC5D at progression. Patient 7 had a 17 mos remission to talquetamab and daratumumab and similarly to patient 6, he acquired biallelic loss of GPRC5D at progression. He subsequently received elranatamab with no response with elevated serum soluble BCMA (sBCMA=638 ng/ml) level and phenotypic and functional evidence of T cell exhaustion. Patients 5, 6 and 7 illustrate the impact of disease burden and the ensuing sBCMA sink effect on the efficacy of anti-BCMA TCEs. Lastly patient 8 had lasting remissions to elranatamab (DOR 13 mos) and subsequently to talquetamab (DOR 13 mos) with no evidence of T cells exhaustion but rather antigenic escape with acquired functional antigenic losses with clonal BCMA (p.Arg27Pro) and subsequently GPRC5D (p.Asp239Asn) mutation. Highlighting the lack of cross resistance between anti-BCMA therapies, our in vitro studies showed that while mutant BCMA (p.Ser30del or p.Pro34del) abrogated teclistamab mediated T cell killing, T cells transduced with teclistamab based scFv CAR retained cytolytic activity. Therefore, TCE resistance derived from BCMA mutations does not preclude retreatment with another anti-BCMA TCE or CAR T. We here describe variable non-overlapping mechanisms mediating resistance to sequential TCE and CAR T therapies. Dynamic surveillance for antigenic escape and functional evaluation of T cell fitness will optimize immunotherapy sequencing.

Leukemic Cell-Intrinsic Innate Nucleic Acid Receptor Signaling Governs Efficacy of Hypomethylating Agents and Immunosurveillance in AML

Introduction: Hypomethylating agents (HMA), such as Azaciditine (AZA), are a long-established treatment option for acute myeloid leukemia (AML). Besides epigenetic reprogramming of malignant cell clones, HMAs are recognized to facilitate antineoplastic immunity. In vitro assessments in solid tumor models suggest that a major mechanism underlying AZA-triggered immune responses may be the activation of innate nucleic acid sensing pathways. As such, the RNA- and DNA-sensing receptor systems, RIG-I/MDA-5 and cGAS/STING - and subsequent type I interferon (IFN-I) signaling seem to be triggered by the transcriptional upregulation of otherwise DNA-hypermethylated and thus silenced endogenous retroviruses (ERVs). In AML, it is unknown whether similar processes are involved and/or by which molecular mechanisms, HMAs modulate anti-leukemic immunity against AML blasts, and how these processes are affected during acquired HMA resistance. Methods: Murine (c1498 and Wehi-3B) and human (MOLM-13) AML cell lines were exposed to AZA in vitro and analyzed for expression of ERVs. Nucleic acid receptor sensing pathways and IFN-I genes are not usually DNA methylated by AZA at promoter regions. However, the re-expression of endogenous nucleic acids or ERVs could trigger their activation. Protein and transcriptional expression of major components of nucleic acid receptor sensing pathways and IFN-I genes were, therefore, analysed. To understand the importance of AML cell-intrinsic nucleic acid receptor signaling in HMA-induced immunosurveillance, syngeneic c1498 and Wehi-3B AML models were employed. Mice received 2 cycles of 2.5mg/kg AZA (6 days on, 5 days off, 6 days on) intraperitoneally to mimic the principal treatment course used in patients. To address the contribution of the nucleic acid-sensing pathways to AZA treatment efficacy in vitroand in vivo, AML cells with acquired AZA resistance (AZA-R) or gene engineered AML cells deficient in RNA receptors (RIG-I/MDA-5), or the RNA- and DNA-sensing adapter proteins (MAVS and STING) were employed. Results: A targeted ERV screen revealed upregulation of various ERV transcripts in c1498 and Wehi-3B cells and was similarly observed in MOLM-13 AML cells following AZA exposure in vitro. Increased RNA transcript and protein expression of RIG-I/MAVS and (to a lesser degree) STING was observed, resulting in activation of downstream constituents including higher phosphorylation of the transcription factors IRF3/7 and NF-kB, IFN-I, and other ISGs. This was abrogated in RIG-I and MAVS, but not STING, deficient murine and human AML cells. Interestingly, expression of RIG-I/MDA-5, STING and all other downstream constituents, but not MAVS, were diminished in AZA-R AML cells. In mice harboring MAVS deficient AML (c1498), HMA treatment failed to show anti-leukemic activity resulting in rapid disease progress and death of recipient animals. Loss of STING in leukemic cells also impacted AZA treatment efficacy, although to a much less pronounced degree. These findings were similarly reproduced with Wehi-3B AML-engrafted mice. Following antibody-mediated depletion of T cells but not NK cells, mice rapidly succumbed to AML disease and demonstrated no anti-leukemic effect of AZA treatment. CyTOF and flow cytometric analysis also revealed increased bone marrow and spleen infiltration as well as activation of CD4 +/CD8 + T cells, NK cells, and MHC-II + APCs/Myeloid cells in AZA treated mice bearing wildtype AML, compared to untreated. This was not observed in AZA-treated mice bearing MAVS-deficient or AZA-R AML. Conclusion: Our findings indicate that nucleic acid receptor signaling (specifically RIG-I/MAVS) within leukemic cells is imperative for AZA efficacy and immunosurveillance in AML. Whether these RNA-sensing receptors are triggered by ERVs or alternate (endogenous) RNAs remains to be determined. Elucidating the molecular mechanisms of how nucleic acid sensors within leukemic blasts shape treatment efficacy of AZA may guide development of systematic immunotherapeutic strategies for AZA-R AML by targeted combinatorial approaches.

Applying the Novel EHA/EBMT Grading System for Icaht Following CAR-T Therapy: Comparative Incidence across Disease Entities and Association with Infections and Mortality

Background: Hematological toxicity is a frequent side effect of CAR-T therapy and predisposes for severe infectious complications. Recently, the EHA/EBMT consensus grading for Immune Effector Cell Associated HematoToxicity (ICAHT) was developed ( Rejeski et al. Blood 2023). In contrast to existing grading systems such as the CTCAE, the novel ICAHT grading integrates both the depth and duration of neutropenia. We hypothesized that ICAHT severity is associated with key clinical sequelae such as transfusion requirements, hospitalization, severe infections, and adverse treatment outcomes. Methods: We applied the novel grading of early ICAHT (day 0-30) to a multicenter retrospective real-world cohort of 549 patients treated with BCMA- or CD19-directed CAR T-cells for relapsed/refractory B-cell malignancies (334 large B-cell lymphoma [LBCL], 112 multiple myeloma [MM], 103 mantle cell lymphoma [MCL]) across twelve international sites (Germany, France, Spain, USA). Hematotoxicity endpoints included the total cumulative duration of severe neutropenia (ANC <500/µL, day 0-60) and phenotypes of neutrophil recovery ( Rejeski et al. Blood 2021). Infections were studied until day +90 after CAR-T and were graded on a 5-grade scale as mild, moderate, severe, life-threatening, or fatal. Non-relapse mortality (NRM) was defined as death following CAR-T without evidence of relapse or progression. Kaplan-Meier estimates of progression-free (PFS) and overall survival (OS) were compared using log-rank test. Results: Our study cohort included 424 patients without severe ICAHT (absent or grade 1-2) and 125 patients with severe ICAHT (grade 3-4). The distribution of mild (1°), moderate (2°), severe (3°) and life-threatening (4°) ICAHT was 36%, 29%, 17%, and 5%. Seventy patients (13%) did not develop ICAHT of any grade. When comparing ICAHT grades across disease entities, we noted a numeric trend towards increased severe ICAHT in MCL compared to LBCL or MM patients (Grade ≥3: 28% vs. 23% vs. 15%). Patients that subsequently developed severe ICAHT displayed elevated serum inflammatory markers and pronounced cytopenia at baseline - reflected by increased CAR-HEMATOTOX scores (median 3 vs. 1, p<0.0001). On multivariate binary logistic regression, co-stimulatory domain (CD28z), low platelet count, low ANC, low hemoglobin, increased serum ferritin, and the presence of bone marrow infiltration were independent risk factors for severe ICAHT. We noted a strong positive correlation between ICAHT severity and the cumulative duration of severe neutropenia (r=0.92, p<0.0001). The aplastic phenotype of neutrophil recovery was enriched in patients with grade 3 (73%) and especially grade 4 ICAHT (100%). Severe ICAHT was also associated with coincident multilineage cytopenias, resulting in increased transfusion requirements for both platelets (85% vs. 21%, p<0.0001) and red blood cells (86% vs. 41%, p<0.0001). In terms of management of hematotoxicity, the severe ICAHT group more commonly received G-CSF (72% vs. 44%, p=0.01), TPO mimetics (12% vs. 2%, p<0.0001) and hematopoietic stem cell boosts (6% vs. 0.2%, p<0.0001). Importantly, patients with severe ICAHT displayed a significantly increased rate of severe infections (49% vs. 13%, p<0.0001, Fig. 1a) and severe bacterial infections (36% vs. 8%, p<0.0001). This translated into a markedly increased 1-year NRM rate (14% vs. 4.5%, logrank p<0.0001, Fig. 1b), which was primarily attributed to fatal infections of fungal or bacterial origin. Of note, the ICAHT grading showed superior discrimination for severe infections (C-index 0.73, 95%CI: 0.67-0.78) compared to CTCAE grading (C-index 0.55, n.s.). Prolonged hospitalization was noted in case of severe ICAHT (median 21 vs. 16 days, p<0.0001) and intensive care admission was more common (23% vs. 4%, p<0.001). Finally, we observed inferior PFS (1-year PFS 35% vs. 51%, median 4 vs. 14 months, p<0.0001) and inferior OS (1-year OS 52% vs. 73%, median 12 months vs. not-reached, p<0.0001) in the patients that developed severe ICAHT. Conclusions: These data highlight the clinical relevance of the novel EHA/EBMT ICAHT grading system. Importantly, ICAHT severity was closely associated with transfusion dependence, increased infection incidence, and adverse treatment outcomes with high NRM. Taken together, these findings argue for reporting ICAHT grades in clinical trials evaluating established and novel CAR constructs.

Ultra High-Risk Multiple Myeloma Patients with Multi-Hit Tumours and SKY92 High Risk Signature Are at Increased Risk of Early Relapse Even When Treated with Extended Intensified Induction and Consolidation - Results from the Optimum/Muknine Trial

Background: We recently reported improved outcomes for patients with ultra-high risk (UHiR) newly diagnosed multiple myeloma (NDMM) by double hit/≥2 high-risk cytogenetic abnormalities (HRCA) and/or SKY92 risk signature or primary plasma cell leukemia (pPCL) in the OPTIMUM/MUKnine (NCT03188172; Kaiser et al, JCO 2023) trial. However, some participants still relapsed within the first 18 months of treatment despite stratified intensive therapy with Dara-CVRd, V-ASCT and extended Dara-VR(d) consolidation. In this analysis we characterise factors associated with early progression. Methods: In OPTIMUM, patients with UHiR NDMM (≥2 HRCA: t(4;14), t(14;16), t(14;20), gain(1q), del(1p), del(17p) or SKY92 high risk signature) or with pPCL received up to 6 cycles of Dara-CVRd induction, V-ASCT, 6 cycles Dara-VRd (Cons1) and 12 cycles Dara-VR (Cons2), before moving to monthly Dara-R maintenance until progression. OPTIMUM recruited 107 UHiR patients, including 9 pPCL. In this exploratory analysis, baseline clinical, laboratory and tumour molecular characteristics were compared between patients who experienced an Early Relapse, defined by MM relapse or MM-related death within 18 months from registration and those who did not, using descriptive statistics and hypothesis testing using two-sample t-tests or chi squared tests. Baseline characteristics were also compared by minimal residual disease (MRD; 10 -5 sensitivity by flow cytometry) status at the end of induction to elucidate whether baseline factors associated with early MRD negativity were overlapping with those associated with Early Relapse. Median follow-up was 51.5 months, and all patients had been on study for over 44 months. Results: Twenty-three (21%) of 107 UHiR patients experienced Early Relapse, versus 84 (79%) who did not. Patient age and gender were not different between groups. Platelet levels as a continuous variable were lower in the Early Relapse group vs those without (mean 179/nL, standard deviation (SD) 92/nL vs. mean 223/nL, SD 77/nL; P=0.0247), whereas haemoglobin, serum creatinine, calcium, presence of soft tissue plasmacytomas (PCM), bone lytic lesions or plasma cell bone marrow infiltration on diagnostic trephine were similar. ISS stage distribution differed between groups (P=0.0203): most Early Relapse participants were ISS stage 2 (13/23 (56.5%) vs 30/84 (35.7%) without Early Relapse), whereas ISS stage 3 was nominally similar (34.8% vs 31.0%). Most notably, only one of the 29 ISS stage 1 patients in OPTIMUM experienced Early Relapse. 57 of 107 (53.3%) patients entered OPTIMUM with ≥2 HRCA at diagnosis, and, of these, seven carried 3 HRCA. Five of seven participants (71.4%) with 3 HRCA experienced Early Relapse, opposed to only seven out of 50 (14%) with only 2 HRCA. 82 of 107 (76.6%) were SKY92 high risk at baseline. Only two of the 24 participants (8.3%) with SKY92 standard risk experienced Early Relapse, as opposed to 20 out of 82 (24.4%) with SKY92 high risk. Of individual HRCAs, only presence of del(17p) was associated with early relapse (P=0.002): 8 of 16 (50%) participants with del(17p) tumours experienced Early Relapse. However, seven of these 8 Early Relapse del(17p) tumours (88%) were also positive for SKY92 high risk signature. In contrast, the majority (62%) of del(17p) that did not relapse early were SKY92 standard risk. Of the 107 UHiR patients, 6 did not reach end of induction and 14 had no MRD result. Of 87 participants with interpretable MRD result at end of induction (EOI), 51% tested MRD-negative (44/87). Of clinical factors, only presence of PCM was associated with insufficient response (P=0.017, 5/5 MRD-positive), whereas ISS stage was not associated with MRD at EOI. Only one of four participants (25%) with 3 HRCA had MRD-negative status at EOI vs 66% of those with 2 HRCA. Also, the majority of patients (62%) identified by SKY92 high risk only were still MRD-positive. Conclusions: Our results suggest that presence of 3 or more HRCA, SKY92 high risk signature or del(17p) combined with SKY92 high risk are all associated with increased risk of Early Relapse despite intensified OPTIMUM treatment, and could help identify patients early who are candidates for novel, innovative first-line therapeutic approaches. Results also suggest utility of integrated molecular diagnostics, including gene expression risk profiling, to support clinical decision making in the era of advanced front-line combination therapies.

Multicenter Prospective Phase II Study of Rituximab Combined, Bortezomib, Lenalidomide, Dexamethasone Followed By Lenalidomide Maintenance (R-VRD) in Patients with Waldenstrom's Macroglobulinemia (KMM1803)

Backgroud: Waldenström macroglobulinemia (WM) is an indolent B-cell malignancy characterized by the presence of immunoglobulin M (IgM) monoclonal gammopathy and lymphoplasmacytic bone marrow infiltration. Recently, the superior efficacy of BTK inhibitors and other novel agents has been established. However, BTK inhibitors has been shown limited efficacy in patients with CXCR4 mutation and MYD88 wild type. Therefore, the importance of chemotherapy which do not contain BTK inhibitors still remain. This study was conducted to estimate the efficacy and safety of the combination of rituximab, bortezomib, lenalidomide and dexamethasone in patients with WM in South Korea. Methods : Between Aug. 2018 and Aug. 2022, a total of 39 patients were included in this study at 12 academic institutes in South Korea. The primary end-point of the study was the median progression-free survival (PFS), and the secondary end-points were the overall survival (OS), overall response rate (ORR), minimal residual disease (MRD) achievement and toxicities. Eligible patients were confirmed clinicopathological diagnosis of WM who has Measurable and symptomatic disease meeting at least 1 of the recommendations from the Second International Workshop on Waldenström Macroglobulinemia (IMWWM) for requiring treatment. Pateints who received rituximab treatment within the last 12 months before the first dose of study drug were excluded. Patients received the 28-day cycle of Rituximab (375 mg/m 2 IV on day 1), Bortezomib (1.3 mg/m 2 SC on day 1, 8, 15), Lenalidomide (15 mg per oral day 1-21) and dexamethasone (20 mg iv or oral day 1-4). Enrolled patients were received induction therapy with rituximab and bortezomib, lenalidomide and dexamethasone every 4 weeks for 6 cycles and then lenalidomide (10 mg on day 1-21) maintenance for 2 years. All patients were checked MYD88 and CXCR4 mutation at the baseline work up of this study and MRD achievement was checked by MYD88 PCR every 6 months for 3 years. Results : The median (range) age was 65.2 years. Lymphadenopathy were noted around 50%. In this study, MYD88 mutation was noted 74.3% and CXCR4 mutation was noted 20%, respectively. The response rates were following: CR in 4 (13.3%), VGPR in 3 (10.0 %) PR in14 (46.7 %), MR in 3 (10.0%) and < MR in 6 (20.0 %). Overall response rates (≥PR (partial response)) rate was 70.0 % and more than MR were 80%. 2yrs PFS and OS were 56% and 93%, respectively. We are now checking MRD by MYD88 PCR for ongoing patients. The detailed response rates and survival outcomes will be reported soon according to MYD88 and CXCR4 mutation status. And comparison of survival difference according to MRD negativity will be also announced after finishing data collection of MRD. Conclusions: R-VRD regiment could be helpful for MYD88 mutation negative or CXCR4 mutation positive patients. BTK inhibitors show superior response and survival outcomes for patients with MYD88 mutation positive and CXCR4 mutation negative. So, we are supposed that R-VRD could be optional treatment for patients who are not suitable for BTK inhibitors.

Multiomic Characterization of Myelodysplastic Neoplasms (MDS) with Micromegakaryocytes Highlights the Role of EZH2-RUNX1 deregulation in Disease Physiopathology and Response to Targeted Therapies

Micromegakaryocytes (micro-MKs), an unequivocal myeloid dysplastic feature in adults, are present in 15-20% of myelodysplastic neoplasms (MDS). We recently associated the detection of these small megakaryocytes with a mono- or bi-lobated nucleus in bone marrow (BM) smears of MDS patients with an unfavorable prognosis. The aim of the present study was to elucidate the molecular bases of micro-MK formation and its impact on MDS response to targeted therapies. We selected retrospectively a cohort of 40 MDS patient samples subjected to NGS myeloid panel and RNA sequencing and carried out a morphological re-evaluation that included micro-MKs recounting. Cases with isolated del(5q) or SF3B1 mutation were excluded. MDS cases were selected according to the following morphological findings: no dismegakaryopoiesis, dismegakaryopoiesis without micro-MK, low rate of micro-MK (<10%; micro-MK low) and high rate of micro-MK (>40%; micro-MK high). No patient harbored an intermediate (10-40%) rate of micro-MK. A comparative characterization of 8 representative patients was carried out subjecting diagnosis BM samples to Tapestri and Chromium single cell proteogenomic and transcriptomic platforms, gene set enrichment analysis, and deep cytogenetic characterization by optical genome mapping. Functional validation studies were performed using the megakaryoblastic cell line MEG01 differentiated to a mature MK phenotype by exposure to phorbol myristate acetate (PMA), as well as using the CRISPR-Cas9 tool for gene editing. Finally, activity of investigational drugs including 5-azacytidine, lenalidomide, venetoclax, rigosertib and pevonedistat, was evaluated in MEG01-activated cells and in vivo using a chicken embryo chorioallantoic membrane (CAM) model of MDS patient-derived xenograft (PDX). The most frequently mutated genes across all cohorts were ASXL1 (58%), SRSF2 (38%), RUNX1 (30%), TET2 (30%), STAG2 (20%), EZH2 (18%), DDX41 (10%), U2AF1 (10%), and ZRSR2 (10%) . Interestingly, EZH2 and RUNX1 mutations were enriched in the micro-MK high group ( EZH2: 0%, 10%, 14.3% vs. 66.7%, p 0.006; RUNX1: 0%, 20%, 35.7% vs. 83.3%, p 0.003), and both mutations co-occurred in 85.7% (6/7) of the EZH2 mutated cases. Single cell analyses revealed an enrichment of RUNX1 alterations in three populations within micro-MK high BM samples, including hematopoietic stem and progenitor cells, non-classical monocytes and immature erythroid cells. These samples were also characterized by a 5-fold increase in MK progenitor abundance and by the upregulation of a set of 10 EZH2-repressed genes in neutrophil-like cells and myeloid progenitors, with 7q loss presumably affecting the EZH2 locus in 50% of the cases with micro-MK. Using the in vitro MK differentiation model, we further demonstrated that EZH2 downregulation hampered the acquisition of MK surface markers CD41 and CD61, and that venetoclax was the sole agent retaining notable cytotoxic activity in differentiated cells when compared to undifferentiated megakaryoblasts. Accordingly, in a first-in-kind in vivo CAM-MDS transplant model, venetoclax was able to impair BM infiltration by human cells in a PDX model of micro-MK+ MDS. In summary, supporting the notion that EZH2 and RUNX1 exert a crucial role in the regulation of megakaryopoiesis, our present findings suggest that deregulation of EZH2-RUNX1 activity by loss-of-function mutation and/or genetic deletion affecting myeloid precursors, impairs a proper megakaryocytic differentiation process in MDS. Thus, this phenomenon may be considered as a characteristic feature of MDS cases with an elevated proportion of micro-MK. Of note, preliminary in vitro and in vivo results support the use of venetoclax for the treatment of this subgroup of patients with dismal outcome.

CD72 is a pan-tumor antigen associated to pediatric acute leukemia.

In the development of novel immunotherapeutic approaches, the step of target identification is a challenging process, because it aims at identifying robust tumor-associated antigens (TAAs) specific for the pathological population and causing no off-target effects. Here we propose CD72 as a novel and robust TAA for pediatric acute leukemias. We provided an outline of CD72 expression assessed by flow cytometry on a variety of cancer cell lines and primary samples, including normal bone marrow (BM) samples and hematopoietic stem and progenitor cells. We analyzed CD 72 expression on a cohort of 495 pathological pediatric BM aspirates, including: 215 B-cell precursor acute lymphoblastic leukemias (BCP-ALL), 156 acute myeloid leukemias (AMLs), 88 T-lineage ALLs or lymphoblastic lymphomas with BM infiltration, 13 B-lineage lymphoblastic lymphomas with BM infiltration, 9 myelodysplastic syndromes with increased blasts (5%-9% blasts on BM: MDS-IB1) and 14 non-hematopoietic solid tumors infiltrating BM. Results showed that CD72 is highly expressed in almost all BCP-ALL and the majority of AML at diagnosis, including BCP-ALL cases characterized by CD19 loss. These findings support a potential role for advanced diagnostics and novel immunotherapy approaches, providing a pan-ALL and AML target.

The impact of diabetes mellitus on hematopoietic stem cell mobilization, a-single center cohort study

BackgroundFactors such as age, underlying hematological disease, chemotherapy and radiotherapy used, and bone marrow infiltration may cause mobilization failure. Several preclinical observed that diabetes mellitus (DM) leads to profound remodeling of the hematopoietic stem cell (HSC) niche, resulting in the impaired release of HSCs. We aim to examine the effect of DM on HSC mobilization and to investigate whether there is a relationship between complications developing in the DM process and drugs used to treat DM and mobilization failure. MethodsIn Erciyes University Bone Marrow Transplantation Unit, 218 patients who underwent apheresis for stem cell mobilization between 2011 and 2021 were evaluated retrospectively. One hundred and nine patients had a diagnosis of DM, and 109 did not. ResultsMobilization failure developed in 17 (15.6 %) of the patients in the DM group, while it developed in 7 (6.4 %) patients in the non-DM group (p = 0.03). CD34+ stem cell count was 8.05 (1.3–30.2) × 106/kg in the DM group, while it was 8.2 (1.7–37.3) × 106/kg in the other group (p = 0.55). There was no statistically significant relationship between glucose and hemoglobin A1c levels and the amount of CD34+ cells (p = 0.83 and p = 0.14, respectively). Using sulfonylurea was the only independent predictor of mobilization failure (OR 5.75, 95 % CI: 1.38–24.05, p = 0.02). ConclusionDM should be considered a risk factor for mobilization failure. Further research is needed fully to understand the mechanisms underlying the mobilization failure effects of sulfonylureas and to develop strategies to improve stem cell mobilization in diabetic patients.

A Pragmatic Approach for Managing Unexplained Neutropenia in a Brain Tumor Patient

Cancer patients experience a decrease in blood counts either due to the myelosuppressive effect of oncological treatment or bone marrow infiltration due to distant metastases. Oncological interventions, such as chemotherapy, immunotherapy or large-field irradiation, are common causes of neutropenia, thrombocytopenia, or pancytopenia in cancer patients. Non-oncological reasons for the decrease in blood counts can be attributed to drug-induced, autoimmune diseases, or viral infections. Recently, case reports have been published for neutropenia/thrombocytopenia due to the Coronavirus disease (Covid-19) pandemic too. Here, we discuss a case of phenytoin-induced neutropenia in a brain tumor patient and a pragmatic approach for managing unexplained neutropenia, that is, neutropenia unrelated to cancer or oncological intervention. Timely recognition and timely intervention can prevent fatal outcomes.

THU468 Finding An Effective Treatment For Osteoporosis In Gaucher Disease

Abstract Disclosure: C. Lesniak: None. M.S. Akula: None. Background: Gaucher disease is a rare autosomal recessive disorder, leading to a deficiency of the enzyme glucocerebrosidase and accumulation of lipid-laden macrophages and dysfunction of multiple organs. The skeletal system is commonly affected resulting in reduced bone mineral density (BMD), marrow infiltration and bone infarction. Enzyme replacement therapy (ERT) has been a mainstay of treatment, and bisphosphonate therapy has been used to help treat osteoporosis, but newer agents are not well studied in this population. Case Description: The patient is a 62 year old female with a history of Gaucher disease Type 1 (GD1) and osteoporosis, treated with alendronate. She was diagnosed with GD1 in childhood and treated with glucocerebrosidase as ERT. She was diagnosed with osteoporosis in 2018 and started on bisphosphonates after a DXA scan showed a T-score at the lumbar spine of −3.2 and -1.4 at the left hip. She denied bone or back pain and has no history of any osteolytic lesions or osteonecrosis. Workup for secondary causes of osteoporosis was negative. She was taking alendronate 70 mg weekly, calcium 1800 mg daily, and vitamin D 4000 IU daily. Labs showed calcium 9.1 mg/dL, TSH 1.530 uIU/mL, PTH 34 pg/mL, and 25-hydroxy vitamin D 38.7 ng/mL. Repeat DXA scan showed worsening osteoporosis with a T-score at the lumbar spine of −3.4 and left hip of −2.5. As her BMD worsened while on alendronate for 3 years, teriparatide was offered as an alternative treatment. Discussion: Gaucher disease is a rare lysosomal storage disorder affecting multiple organs. Up to 90% of patients with GD1 have bone involvement of some kind. DXA scan should be done soon after diagnosis. Reduced BMD in GD1 is common and is associated with increased fracture risk. ERT has been the main management option to treat bone manifestations with improvement in BMD shown after 3-5 years. After 8 years of treatment with ERT, patients have been shown to reach the BMD of the age and sex matched population. In addition to ERT, calcium and vitamin D3 are recommended to increase BMD. There is no standard of treatment for osteoporosis in Gaucher patients, although bisphosphonates have been shown to improve BMD. Had our patient had early DXA scans, treatment may have been initiated sooner. A single case report showed improvement in BMD with the use of teriparatide after bisphosphonate failure. The efficacy of alternative agents, such as teriparatide and romosumab, in treating osteoporosis in patients with Gaucher disease needs to be further investigated. Presentation: Thursday, June 15, 2023

Identification of focal lesion characteristics in MRI which indicate presence of corresponding osteolytic lesion in CT in patients with multiple myeloma.

The presence of bone marrow focal lesions and osteolytic lesions in patients with multiple myeloma (MM) is of high prognostic significance for their individual outcome. It is not known yet why some focal lesions seen in MRI, reflecting localized bone marrow infiltration of myeloma cells, remain non-lytic, whereas others are associated with destruction of mineralized bone. In this study, we analyzed MRI characteristics of manually segmented focal lesions in MM patients to identify possible features that might discriminate lytic and non-lytic lesions. The initial cohort included a total of 140 patients with different stages of MM who had undergone both whole-body MRI and whole-body low-dose CT within 30 days, and of which 29 satisfied the inclusion criteria for this study. Focal lesions in MRI and corresponding osteolytic areas in CT were segmented manually. Analysis of the lesions included volume, location and first order texture features analysis. There were significantly more lytic lesions in the axial skeleton than in the appendicular skeleton (p = 0.037). Out of 926 focal lesions in the axial skeleton seen on MRI, 544 (59.3 %) were osteolytic. Analysis of volume and first order texture features showed differences in texture and volume between focal lesions in MRI with and without local bone destruction in CT, but these findings were not statistically significant. Neither morphological imaging characteristics like size and location nor first order texture features could predict whether focal lesions seen in MRI would exhibit corresponding bone destruction in CT. Studies performing biopsies of such lesions are ongoing.

Clinical relevance of cyclooxygenase 2 and vascular endothelial growth factor-A expression in classical Hodgkin lymphoma

Abstract Background Classical Hodgkin lymphoma (cHL) is a clonal lymphoid neoplasm derived from B cells. Cyclooxygenase 2 (COX2) and vascular endothelial growth factor-A (VEGF-A) play major roles in angiogenesis and impact cHL prognosis. Aim To measure COX2 and VEGF-A expression in cHL patients and assess their potential association with other laboratory and clinical parameters. Patients and methods Seventy-six cHL bone marrow (BM) biopsy specimens were histopathologically examined and immunohistochemically stained for COX2 and VEGF-A expression. Correlations between COX2 and VEGF-A expression and clinicopathologic factors were evaluated. Results COX2 and VEGF-A were expressed in 67/76 (88.2%) and 48/76 (63.2%) of BM specimens, respectively. VEGF-A was associated with advanced cHL stage (P=0.044) and BM infiltration confirmed by CD30 positivity (P=0.023). A significant association was found between VEGF-A positivity and mediastinal lymphadenopathy (P=0.049), inguinal lymphadenopathy (P=0.046), and pulmonary nodules (P=0.048). COX2 positivity was significantly associated with cervical lymphadenopathy (P=0.011). A positive association was found between expression of both markers (COX2 and VEGF-A) (P=0.001). Coexpression of COX2 and VEGF-A was associated with disease staging (P=0.016), mediastinal lymphadenopathy (P=0.019), and inguinal lymphadenopathy (P=0.044). Conclusion COX2 and VEGF-A, as major players in angiogenesis, are associated with tumor progression in cHL. These findings support targeting both markers as the potential therapeutic approach in cHL.

Bone marrow composition features and possibilities of tumor involvement diagnosing in patients with classic Hodgkin’s lymphoma

Background. Classical Hodgkin’s lymphoma is a B-cell lymphoproliferative disease, the tumor substrate of which is Berezovsky–Reed–Sternberg cells, characterized by CD30, PAX-5, CD15 expression and the absence of CD3, CD45. In some cases, tumor cells express CD20. modern anticancer therapy has increased the survival probability for most patients, not only with early but also with advanced stages of classical Hodgkin’s lymphoma. Such successes are mainly due to the distribution of patients into prognostic groups and the choice of an appropriate treatment regimen. tumor infiltration of the bone marrow suggests assigning patients to the advanced stages group, followed by the choice of an intensive therapy program. Aim. To determine the bone marrow involvement frequency according to positron emission tomography combined with computed tomography (PET/CT), with 18F-fluorodeoxyglucose (FDG) and bone marrow trephine biopsy (bmtb), to compare the results obtained with primary tumor immunophenotype and bone marrow cellular composition, and to identify of prognostic risk factors. Materials and methods. The study included 107 patients with newly diagnosed classical Hodgkin’s lymphoma, who underwent a diagnostic examination at the moscow research institute of oncology named after P. A. Herzen – a branch of the National Medical Research Center for Radiology and the “Lapino” clinical Hospital from 2015 to 2022, followed by anticancer therapy and further follow-up. Morphology of the primary tumor biopsy specimen in all patients and immunohistochemical (IHC) study using a wide panel of monoclonal antibodies (CD15, CD30, CD3, CD45, CD20, PAX-5 anti-gens; in some cases epstein–barr virus proteins expression) in most cases were performed. All patients underwent a morphological and / or IHC study of BMTB and the majority underwent aspiration biopsy and PET/CT with 18F-FDG. Results. The most common histological variant of classical Hodgkin’s lymphoma was nodular sclerosis (86.9 %). The majority of patients (51.4 %) were assigned to the advanced stage prognostic group. bone marrow tumor infiltration was statistically significantly more frequently diagnosed during PET/CT with 18F-FDG compared with the results of the BMTB – in 27.1 % and 12.1 % of cases, respectively (p < 0.05). when comparing the results of both diagnostic methods, it was found that in 17.1 % of cases, bone marrow infiltration, detected during PET/CT, was not confirmed by IHC examination of the trephine biopsy. In addition, it was found that the majority of cases with CD20+/± and CD15+/± expression in the primary tumor were observed in the group of patients without bone marrow involvement. when assessing the cellular composition of bone marrow aspirates, it was revealed that in patients with bone marrow tumor infiltration, an increase in cellularity and megakaryocytes number along with a decrease in the plasma cells number is observed. Conclusion. The results suggest further study of bone marrow immunomorphological features in order to identify prognostic factors and search for new therapeutic targets. a more extended analysis of bone marrow aspirate immunomor-phological characteristics using new modern diagnostic methods, minimal residual disease status as a surrogate marker seems to be relevant and necessary to confirm the depth of the antitumor response achieved. Detection of CD20+/±- and cd15+/±-Berezovsky–Reed–Sternberg cells according to primary tumor IHC analysis indicates a low probability of bone marrow tumor infiltration, but further analysis is required on a large clinical and laboratory material.

The role of IgG4-positive plasma cell population in classic Hodgkin lymphoma.

The effect of IgG4, which constitutes the least of the IgG subclasses, on the pathogenesis and prognosis of lymphoma or solid tumors is one of the research topics of interest in recent years. The role of IgG4, which has been reported to suppress antitumor immunity, in classic Hodgkin's lymphoma (cHL), which is recognized by its pathognomonic microenvironment, is not yet clearly known.The aim of this study was to determine IgG4-positive plasma cell density in the cHL microenvironment and to compare it with histopathological and clinical parameters. In addition, the role of the increase in IgG4-positive cells in the development of relapse after treatment was also investigated.A retrospective cross-sectional study.Ninety-four patients with the initial diagnosis of cHL who had no comorbidity or no treatment history and forty-one reactive lymph nodes with follicular hyperplasia findings were included in the study. Three hot-spot areas were identified with reference to the IgG4 sections. Mean IgG4-positive plasmacyte counts and IgG4/IgG ratios were determined and compared with histopathological characteristics.The mean IgG4 + plasma cell count was 33.57 in cHL cases and 47.04 in the control group (p = 0.233). IgG4/IgG ratio was significantly higher in cHL compared with the control group (0.27 vs. 0.21, p = 0.021). The IgG4/IgG ratio was found to be higher in younger patients with classic Hodgkin lymphoma, with a low correlation (p = 0.028, r = - 0.226). There was no relationship with gender, lymph node location, histological subtype, EBV positivity and bone marrow infiltration. It was observed that IgG4/IgG ratio was higher in early-stage patients (p = 0.022). No significant IgG4 + cell increase was detected in the initial diagnosis and relapse slides of six patients who developed relapse after standard treatment, resulting in a cure.Novel therapeutic modalities targeting microenvironmental components have been reported to show dramatic effects, particularly in relapsed or refractory patients. Detailed characterization of the cHL inflammatory milieu will be useful for the identification of alternative targets. IgG4 subclass antibodies, which have been described to have anti-inflammatory effects, may have prognostic significance in a proportion of cHL patients.

Variant histology of pediatric nodular lymphocyte-predominant Hodgkin lymphoma with IgD and CD30 expression.

Nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL), recently known as nodular lymphocyte-predominant B-cell lymphoma (NLPBL), accounts for 5%-10% of Hodgkin lymphoma (HL). Different morphologic patterns of NLPBL are identified and categorized as typical patterns (type A and B) and variant histologic patterns (types C, D, E, and F). We investigated different morphologic patterns, CD30 and IgD expression in pediatric patients with NLPBL diagnosed at the Children's Cancer Hospital Egypt. Forty-six (53%) of the patients exhibited a typical histologic pattern, whereas the remaining (47%) exhibited variant histologic pattern. Variant histology is associated with unfavorable clinical characteristics, such as advanced stages, B-symptoms, and extranodal involvements, particularly bone marrow and bone infiltration, with p-values of .06, .05, and 0.01%, respectively. Additionally, 39% of patients with variant histology experienced disease progression or relapse, compared to only 15.2% of patients with typical patterns (p=.009). Types C and D are related to decreased event-free survival (EFS), as shown by a p-value of .05. The 5-year EFS for patients with variant histology was 94.4% for the rituximab, cyclophosphamide, vincristine, doxorubicin, and prednisone (RCHOP) versus 33.3% for the adriamycin, bleomycin, vinblastine, and dacarbazine (ABVD). IgD expression in lymphocyte-predominant (LP) cells was detected in 44 (50%) patients, while CD30 expression in LP cells was found in 39 (44%) patients. Variant histology of NLPBL was associated with advanced disease stages and a poor prognosis, while expression of IgD and CD30 in LP cells was not. The poor outcome of variant histology improved with the RCHOP regimen.

Refractory/Relapsed High-Grade B-Cell Lymphoma in the Elderly: A Special Therapeutic Challenge

BACKGROUND: According to the 2016 World Health Organization classification of lymphoid neoplasms, high- grade B-cell lymphoma (HGBL) is defined as a new category for aggressive diffuse large B-cell lymphomas (DLBCL), including DLBCL NOS as well. CASE REPORT: An 80-year-old patient was admitted because of an enlargement of the lymph node located in the right neck region. The patient underwent 6 cycles of R-CHOP, which is considered to be the standard treatment for non-Hodgkin lymphomas (NHL) DLBCL (NOS) CSII B “Bulky,” and he subsequently achieved complete remission (CR). A lymph node biopsy was performed, PH No. 12742/21, which revealed the following: LCA+, CD79 α CD20+, and CD5+, in approximately 50% of the cells, NHL DLBCL (NOS) was of GCB origin, etc. The international prognostic index risk score was 2, the cumulative illness rating scale score was 4. In addition, no bone marrow infiltration was reported. A COP-based chemotherapy protocol was administered, after which the evaluation showed disease relapse. Multi-slice spiral computed tomography (MSCT) follow-up showed an enlarged conglomerate of lymph nodes in all the neck levels. Dg: NHL DLBCL (NOS) CS IVB “Bulky” E (the hypopharynx). The echocardiography results were the following: (EF 50%, aortic insufficiency with MR1+, TR1+ of the aortic valve 3+). The patient was presented to the Consilium, who decided to apply the following therapy (Polatuzumab vedotin + Rituximab + Bendamustine). After III cycle of treatment, MSCT follow-up was performed. The patient gained weight, oral food intake was enabled, whereas the quality of life was significantly improved. CONCLUSION: The administration of ta treatment may be provided to elderly patients with relapsed HGBL.

Discriminating minimal residual disease status in multiple myeloma based on MRI: utility of radiomics and comparison of machine-learning methods

To explore the possibility of discriminating minimal residual disease (MRD) status in multiple myeloma (MM) based on magnetic resonance imaging (MRI) and identify optimal machine-learning methods to optimise the clinical treatment regimen. A total of 83 patients were analysed retrospectively. They were divided randomly into training and validation cohorts. The regions of interest were segmented and radiomics features were extracted and analysed on two sequences, including T1-weighted imaging (WI) and fat saturated (FS)-T2WI, and then radiomics models were built in the training cohort and evaluated in the validation cohort. Clinical characteristics were calculated to build a traditional model. A combined model was also built using the clinical characteristics and radiomics features. Classification accuracy was assessed using area under the curve (AUC) and F1 score. In the training cohort, only the bone marrow (BM) infiltrate ratio (p=0.005) was retained after univariate and multivariable logistic regression analysis. In T1WI, the linear support vector machine (SVM) achieved the best performance compared to other classifiers, with AUCs of 0.811 and 0.708 and F1 scores of 0.792 and 0.696 in the training and validation cohorts, respectively. Similarly, in FS-T2WI sequence, linear SVM achieved the best performance with AUCs of 0.833 and 0.800 and F1 score of 0.833 and 0.800. The combined model constructed by the FS-T2WI-linear SVM and BM infiltrate ratio outperformed the traditional model (p=0.050 and 0.012, Delong test), but showed no significant difference compared with the radiomics model (p=0.798 and 0.855). The linear SVM-based machine-learning method can offer a non-invasive tool for discriminating MRD status in MM.

Diagnostic and Prognostic Value of 18F-FDG PET/CT in Bone Marrow Infiltration of Newly Diagnosed Diffuse Large B-Cell Lymphoma

To explore the diagnostic value of 18F-FDG PET/CT in bone marrow infiltration (BMI) of newly diagnosed diffuse large B-cell lymphoma (DLBCL), compared with the results of bone marrow biopsy (BMB) and investigate whether the BMI diagnosed by 18F-FDG PET/CT and other factors have independent prognostic values. Ninety-four newly diagnosed DLBCL patients who underwent PET/CT in Clinical Medical College of Shanghai General Hospital of Nanjing Medical University were included. BMB was performed within 2 weeks before or after PET/CT, and standardized treatment was performed after PET/CT. The manifestations of bone marrow (BM) FDG uptake were recorded. The diagnostic criteria of BMI were BMB positive or focal BM FDG uptake confirmed by imaging follow-up. The relationship between clinical features and BM FDG uptake and the values of PET/CT and BMB in the diagnosis of BMI was analyzed. The progression-free survival (PFS) was analyzed by Kaplan-Meier survival curves, log-rank test was used to compare PFS rate, and Cox regression model was used to analyze the independent risk factors affecting PFS. Among 94 DLBCL patients, 34 patients showed focal BM uptake (fPET), 7 patients showed super BM uptake (sBMU), 11 patients showed diffuse homogenous uptake higher than liver (dPET), and the other 42 patients had normal BM uptake (nPET) (lower than liver). BMB positive was found in all sBMU patients, in 20.6%(7/34) of fPET patients, and in 27.3% (3/11) of dPET patients. All nPET patients had negative BMB results. dPET patients were associated with lower hemoglobin level and leukocyte count compared with nPET group (P < 0.001, P =0.026). Compared with fPET patients, sBMU patients were more likely to have B symptoms and elevated lactate dehydrogenase (LDH). A total of 44 patients were diagnosed BMI, including 17 cases with BMB+. The sensitivity and specificity of BMB in the diagnosis of BMI was 38.6% (17/44) and 100% (50/50), respectively. Using fPET and sBMU as criteria of PET BMI, the diagnostic sensitivity and specificity of PET/CT was 93.2% (41/44) and 100% (50/50), respectively. Kaplan-Meier analysis showed that there was no significant difference in 2-year PFS rate between nPET and dPET patients (P >0.05), while sBMU patients had lower 2-year PFS rate compared with fPET patients (P < 0.001). Multivariate analysis showed that higher Ann Arbor stage (HR=9.010, P =0.04) and sBMU (HR=3.964, P =0.002) were independent risk factors affecting PFS. Increased BM FDG uptake of DLBCL can be manifested as dPET, fPET and sBMU. fPET and sBMU can replace BMB to diagnose BMI. Although dPET cannot completely exclude the possibility of BMI, it does not affect the prognosis, so it can be diagnosed as PET BMI negative. sBMU is an independent prognostic risk factor.

Utility of bone marrow examination in retinoblastoma and their correlation with hematological features.

Retinoblastoma makes up about 3% of all childhood malignancies. The frequency of metastatic retinoblastoma ranges from 4.8 to 11%. Assessing the bone marrow status of newly diagnosed patients is crucial because of the advantages of autologous bone marrow transplants for high-risk patients. This study aimed to determine the utility of bone marrow examination in cases of retinoblastoma and its correlation with hematological findings. This retrospective study was conducted at the Department of Pathology, King George's Medical University, Lucknow, India. A total of 34 cases of retinoblastoma with bone marrow examination were included in the study. Bone marrow infiltration was present in 17.65% (6/34) cases of retinoblastoma. Bone marrow aspirate myelogram showed that marrow metastasis in retinoblastoma was significantly linked with a reduced percentage of total myeloid cells (p=0.001) and segmented cells (p=0.006). The present study demonstrated that 15% (3/20) of retinoblastoma patients previously classified as nonmetastatic before bone marrow examination (stages I to III based on histology, imaging, and bone scan) had bone marrow metastases following bone marrow examination and were upgraded to stage IV. To conclude, a diligent and exhaustive search for metastatic cells in bone marrow is advised if the myelogram shows a reduced percentage of total myeloid and segmented cells. All stage II and stage III cases of retinoblastoma must undergo bone marrow examination for early metastasis detection, as it may result in an upgrade to stage IV disease, impacting the prognosis and necessitating distinct treatment modalities.

Prolonged cytopenia following CD19 CAR T cell therapy is linked with bone marrow infiltration of clonally expanded IFNγ-expressing CD8 T cells

Autologous anti-CD19 chimeric antigen receptor Tcell (CAR T) therapy is highly effective in relapsed/refractory large B cell lymphoma (rrLBCL) but is associated with toxicities that delay recovery. While the biological mechanisms of cytokine release syndrome and neurotoxicity have been investigated, the pathophysiology is poorly understood for prolonged cytopenia, defined as grade ≥3 cytopenia lasting beyond 30days after CAR T infusion. We performed single-cell RNA sequencing of bone marrow samples from healthy donors and rrLBCL patients with or without prolonged cytopenia and identified significantly increased frequencies of clonally expanded CX3CR1hi cytotoxic Tcells, expressing high interferon (IFN)-γ and cytokine signaling gene sets, associated with prolonged cytopenia. In line with this, we found that hematopoietic stem cells from these patients expressed IFN-γ response signatures. IFN-γ deregulates hematopoietic stem cell self-renewal and differentiation and can be targeted with thrombopoietin agonists or IFN-γ-neutralizing antibodies, highlighting a potential mechanism-based approach for the treatment of CAR T-associated prolonged cytopenia.