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Introduction: Complex karyotype (CK, ≥3 chromosome (chr) abnormalities (abn)) is an important adverse prognostic indicator in chronic lymphocytic leukemia (CLL). CK at diagnosis (dx) of CLL, particularly with major structural chr abn (i.e. unbalanced translocation, add, marker, ring chr), called type-2 CK (CK2), has been associated with an increased risk of Richter transformation (RT) (Visentin Haematologica 2022). RT is defined as development of aggressive lymphoma, most often large B-cell lymphoma, in the setting of CLL. In patients (pts) with relapsed/refractory CLL treated with ibrutinib, CK as a continuous variable and the presence of polyploidy were independent predictors for RT. CK is a common finding at the time of RT, and high-CK (≥5) has been associated with short survival in RT, although previous studies predominantly included pts with prior chemoimmunotherapy (CIT) administration for their CLL. The prognostic significance of CK in pts with RT whose prior CLL-directed therapies include only non-CIT, as is the current standard of care for CLL, has not been evaluated. Methods: We conducted a multicenter, retrospective analysis of pts from 14 academic centers. Pts with RT diagnosed between 6/2011 to 6/2023, who had CLL-directed treatment that did not include prior CIT, with stimulated karyotype data available, were included. Pts who did not receive treatment for their CLL prior to developing RT were not included. Baseline pt, disease, and cytogenetics data were collected via chart review at time of CLL diagnosis and at the development of RT. Karyotype abn up to 20 were counted on both CLL tissue (peripheral blood or bone marrow) and RT tissue using IWGMC guidelines (Chun Leuk Res 2010). CK was categorized as CK1 (balanced abn, deletion, aneusomies) or CK2. Polyploidy was defined as ≥58 chrs. Karyotype was considered evolved if one or more chr abn were seen in a follow-up sample of CLL tissue that were not seen at CLL dx.TP53 disruption was defined as presence of del(17p) or TP53 mutation. Overall survival (OS) was measured from RT dx and estimated using the Kaplan-Meier method. Cox regression model was used to identify prognostic factors associated with OS. Results: A total of 64 eligible pts were identified. Median age at RT dx was 65 years (range 40-89) and 71.9% of pts were male. Of those evaluated (n=49), 79.6% had unmutated IGVH. Median number of therapies for CLL prior to RT was 1 (range 1-5) and included BTK inhibitor (n=37), BCL2 inhibitor (n=3), both (n=18), or other non-CIT treatment (n=6). At CLL diagnosis, 54.7% of pts had a CK, and the median number of chr abn was 3 (range 0-20). Of those with CK, 96.9% had a CK2, and 6.3% had a polyploid subclone. TP53 disruption was found in 46% of pts. At time of RT, chr analysis of CLL tissue was available for 38 pts and showed 78.9% had a CK, and the median number of chr abn was 8 (range 0-20). Polyploidy was found in 29.6%. TP53 disruption (46 pts evaluated) was found in 52.2%. Karyotype evolution from dx (35 pts evaluated) occurred in 74.3% of pts. In RT tissue, of those evaluated (n=29), 96.6% were clonally related to the preceding CLL. MYC translocation (45 pts evaluated) occurred in 17.8%. CK (20 pts evaluated) was found in 70%, with a median number of chr abn of 8 (range 0-20). Of those with CK, 33.3% had a polyploid subclone. With a median follow-up of 17.8 months (range 2.1-83.0) there were 42 deaths, with a median OS of 14.3 months (range 6.9-29.1). For this subset of patients with karyotype data available who would go on to develop RT, an exploratory univariable analysis for OS from RT found that increasing number of chr abn as a continuous variable at CLL dx was associated with worse OS (HR 1.10, 95% CI 1.02-1.19, p=0.01). Similarly, at RT, increasing number of chr abn in CLL tissue (HR 1.09, 95% CI 1.02-1.16, p=0.01) and in RT tissue (HR 1.09, 95% CI 1.01-1.18, p=0.03) was also prognostic of survival. Karyotype evolution in CLL tissue at RT (HR 3.02, 95% CI 1.02-8.94, p=0.05) was borderline significant for worse OS. Conclusions: Our multi-center study identified increasing number of chr abn at CLL diagnosis and at time of RT, and clonal evolution in the CLL tissue, are associated with worse OS in pts with RT whose CLL was treated without CIT. Limitations include incomplete cytogenetics data across the cohort and potential variability across institutions in cytogenetics laboratory practices. This provides further evidence for the clinical utility of chr analysis in the modern era of CLL therapy.

Monoclonal gammopathy of undetermined significance (MGUS), smoldering multiple myeloma (SMM), and active multiple myeloma (MM) represent a continuum across the spectrum of plasma cell disorders. While patients with MGUS can be observed, it has a risk of progression to MM, while patients with SMM have a higher risk of progression to MM. Determining the risk of progression is important for proper patient care and elimination of anxiety, especially for patients identified at very low risk of progression. In contrast, identifying patients at high risk may reduce morbidity by more active surveillance or the introduction of therapy. We hypothesized that Fourier Transform InfraRed Spectroscopic analysis of serum combined with machine learning (FTIR/ML) could be used to facilitate this decision-making and correctly stratify patients' risk. Methods: After Institutional Review Board approval, we identified 99 patients with MGUS who did not progress to SMM/MM or AL amyloidosis, 96 patients with SMM who did not progress to active MM over a 2-year interval from diagnosis, and another 96 SMM patients who progressed to MM within two years of diagnosis. The patients had been diagnosed and followed up at Mayo Clinic in Rochester. Serological molecular fingerprint analysis was then performed using surface- and chemical-enhanced infrared absorption FTIR spectroscopy combined with artificial neural network ML. A randomized 10-fold cross-validation analysis was performed using 262 samples for training and the remaining 29 samples for validation to assess the model across ten independent iterations. Receiver operator characteristic (ROC) analysis was used to assess the FTIR/ML algorithm output compared to the clinical outcome data. Results: The patients with both MGUS and SMM had a similar median age (64.4 years), but patients with SMM tended to have lower hemoglobin compared to MGUS (median 12.4 versus 13.8g/dl respectively). As expected, patients with SMM also had a higher serum M-spike (2.0g/dl versus 1.2) and a higher clonal plasma cell burden in the bone marrow (20% versus 9%). FTIR/ML was able to correctly classify sera into MGUS in 95.8% of samples and SMM in 92.9% of samples. This gave an average accuracy of 94.8%. We performed ROC analysis and determined an area under the curve of 98.7%. The F1 score/precision was 94.9%, with a recall of 94.8%. After establishing a suitable threshold, the ML algorithm was able to correctly classify MGUS in 96.8% and SMM in 97.2% of cases. Conclusion: A single serum test at the time of diagnosis can correctly distinguish between MGUS that will not progress to another plasma cell disorder from smoldering multiple myeloma with a high degree of accuracy. Given that the patients with MGUS that were chosen had not progressed to a plasma cell disorder and were correctly identified, this methodology offers an opportunity to provide reassurance and minimize the need for repeat testing and follow-up of such patients.

The prognosis of patients with immunoglobulin light or heavy chain amyloidosis (AL/AH) has improved with the advent of more effective therapies. However, diagnosis is often delayed, with a negative impact on overall survival due to irreversible end-organ damage. Therefore, technologies that could facilitate the diagnosis or raise early suspicion of AL/AH amyloidosis in patients would be beneficial to improve outcomes. We hypothesized that Fourier transform infrared spectroscopic analysis of serum combined with machine learning (FTIR/ML) may be able to correctly diagnose AL/AH amyloidosis compared to patients with monoclonal gammopathy of undetermined significance or smoldering multiple myeloma. Methods: After institutional Review Board approval, we identified 90 patients with AL/AH amyloidosis, 99 patients with MGUS, and 192 patients with smoldering multiple myeloma (96 each who did/did not progress to active myeloma within two years of diagnosis) that had been diagnosed and followed up at Mayo Clinic in Rochester. We then performed surface- and chemical-enhanced infrared absorption FTIR/ML-based molecular fingerprint analysis on serum samples taken from the time of diagnosis to train an AI algorithm to distinguish between the two cohorts. A randomized 10-fold cross-validation analysis was performed using 253 samples (90% from each group) for training and the remaining 29 for testing to assess the model across ten independent iterations. We performed a Receiver Operator Characteristic analysis of the outcomes to measure the model's performance. Results: The patients with immunoglobulin-related amyloidosis had involvement of one or more of the following organs: heart, kidneys, liver, nerve, and gastrointestinal tract. Patients diagnosed with amyloidosis had lower serum albumin (3.0 versus 3.6 g/dl) and higher lambda immunoglobulin-free light chain values compared to those with MGUS (28.4 versus 1.92mg/dl). The predominance of lambda immunoglobulin-free light chains is not unexpected but not diagnostic by itself of AL/AH amyloidosis. Patients with SMM had higher serum M protein, higher immunoglobulin kappa free light chains, and higher bone marrow plasma cell burden (20%) compared to either MGUS (9%) or AL amyloidosis patients (10%). However, none of these are diagnostic features. FTIR/ML was able to correctly classify AL/AH amyloidosis in 80% of samples and MGUS in 83.8%, for an accuracy of 82% with an area under the curve of 89.2%. The precision was 82%, with a recall of 82%. After setting an appropriate threshold, the algorithm was able to correctly identify AL/AH amyloidosis in 86.1% of patients and MGUS in 86.6% of patients. When we compared AL/AH amyloidosis with SMM, FTIR/ML correctly classified AL/AH amyloidosis in 94.4% and SMM in 96.4% for an accuracy of 95.7% and an area under curve of 97.5%. The precision was 95.8%, with a recall of 95.7%. After setting a threshold, the algorithm was able to correctly diagnose SMM in 98.3% and AL/AH amyloidosis in 96.2%. Discussion: FTIR/ML analysis of serum can distinguish between AL/AH amyloidosis and both MGUS and SMM with a high degree of accuracy. Given that the diagnosis of immunoglobulin related amyloidosis is often delayed, our approach, based on a single analysis of a serum sample could potentially accelerate the diagnosis of AL/AH amyloidosis and implementation of life saving therapy.

Background: Isatuximab is an IgG1κ monoclonal antibody that binds with high affinity to CD38 expressed on plasma cells in light chain (AL) amyloidosis. Anti-CD38 antibodies have shown efficacy alone and in combination in a variety of settings for patients with multiple myeloma and light chain (AL) amyloidosis. Here we report the final analysis of a multi-center, cooperative group prospective phase II study of isatuximab in previously treated patients with AL amyloidosis (NCT03499808). Methods: Eligibility included: age ≥18 years, relapsed or refractory systemic AL amyloidosis, ≥1 prior line of therapy, measurable disease, ≥1 organ involved, not refractory to daratumumab, Eastern Cooperative Oncology Group performance status ≤2, creatinine clearance ≥25 mL/min, and NT-proBNP ≤8500 pg/mL. Patients received isatuximab intravenously 20 mg/kg weekly during the first 28-day cycle and every other week during cycles 2 through 24 for a maximum of 24 cycles. The primary objective was hematologic response with secondary objectives of organ response, safety, progression free survival, and overall survival. Results: Forty-three patients were registered, with 35 patients being eligible for response. The median age of the evaluable patients was 70 years (range, 40.1-79.5) with the majority (66%, n=23) having a lambda clonal plasma cell dyscrasia. The most common cytogenetic abnormality using fluorescence in situ hybridization was translocation t(11;14) observed in ten patients (29%). The most common prior treatment was a proteasome inhibitor (94%, n=33) while 46% (n=16) had undergone autologous stem cell transplant. Eighteen patients (51%) had single organ involvement while 17 (49%) had multiple organs involved. The distribution of organ involvement was typical for AL amyloidosis with cardiac involvement in 25 patients (71%) and renal involvement in 14 (40%). As of December 30, 2022, no new safety concerns were identified. The most common treatment related grade ≥3 adverse events included lymphopenia (n=3, 8.5%) and infection (n=2, 6%). The overall hematologic response rate was 77.1% with a rapid median time to partial response or better of 1.1 months. Two patients (6%) achieved a hematological complete response (CR), 18 (51%) had a very good partial response (VGPR), and 7 (20%) had a partial response (PR). At 24 months from hematologic response, the rate of patients still in response was estimated at 81% (95% confidence interval (CI): 67, 96). The 24-month estimated overall survival was 85% (95% CI: 73%, 97%). Renal response occurred in 50% (7/14) of patients with renal involvement with a median time to response of 18.5 months. Cardiac response occurred in 56% (14/25) of patients with cardiac involvement with a median time to response of 16.6 months. Conclusions: Isatuximab monotherapy resulted in high rates of hematologic response in relapsed AL amyloidosis which translated into organ responses. Treatment appears safe and was well tolerated. Support: NIH/NCI/NCTN grant awards U10CA180888, U10CA180819, CA180820, and CA180821; and in part by Sanofi-Aventis (Sanofi US)

Introduction: The presence of integrative oncology programs in cancer care institutions is rapidly increasing globally, however specialized training in integrative oncology is still limited. In 2022, we launched the first Integrative Medicine in Hematology Oncology (IMHO) fellowship within a traditional Accreditation Council for Graduate Medical Education (ACGME) Hematology Oncology Fellowship in the US. In 2024, the fellowship received accreditation from the Academic Consortium for Integrative Medicine and Health. Here we describe the educational model and report on the fellowship experience via qualitative analysis. Methods: Fellows are recruited from Hematology Oncology Fellows at University of Arizona and Mayo Clinic Arizona. A total of 1000+ hours of Integrative medicine curriculum is completed over 3-years to fulfill American Board of Integrative Medicine requirements for board eligibility. Curriculum is a hybrid delivered via The Andrew Weil Center for Integrative Medicine Foundational Fellowship Curriculum (550 hours), dedicated Integrative Oncology curriculum of didactic and clinical training (250 hours), and research training and investigator-initiated project (200 hours).. Didactic and clinical compentecy-based assessments are required for programmatic completion. Interview-based assessments of acceptability are conducted annually throughout the fellowship duration. Results: IMHO Model Acceptability: Successful recruitment occurred annually since the program's inception (2022, 2023, 2024) of at least 2 fellows of 8 traditional ACGME matched fellows. Additionally, ACGME fellows expressed interest in IMHO fellowship exceeding IMHO recruitment goals. The optimal year of start for IMHO fellowship was determined to be post-graduate year 4 (PGY-4). Five of seven fellows met research goal milestones, and it was determined robust mentorship and research should also start in PGY-4 year. Incentives and cohort visible “dashboard” of progress was deemed necessary when online curriculum milestones were not routinely met by fellows. We received accreditation from the Academic Consortium for Integrative Medicine and Health in spring of 2024. Our first fellow graduate completed requirements in 2024 and is board-eligible in Hematology, Oncology, and Integrative Medicine. Qualitative Analysis: Fellows actively participating in the IMHO fellowship program participated in focus groups. Common themes included: 1) application of resiliency building applied to fellows lives personally and 2) providing tools that allowed them to incorporate integrative medicine to enhance the overall care of their patients. One Fellow stated, “I don't regret picking this choice (the IMHO Fellowship) because I have seen that from my own experience with the patients that I've been able to help them throughout their journey with cancer ...using aspects of Integrative Medicine.” In applying the tools clinically another stated, “I feel like we're really trying to treat the person as a whole, not just treating their condition, and we're really emphasizing their overall goals in life beyond just whatever diagnosis that they have.” One fellow pointed out in regard to their own resiliency “the fellowship program has actually helped improve my resilience and my own wellness ”and “I think it's a really good foundation to have for the future” and another stated “I think it helps me not fall off track because it's a constant reminder of things that you're already interested in, and things that you believe in, that are good coping mechanisms and good ways to kind of, find a balance in your life with your own wellbeing and the wellbeing of others around you.” Finally, “I would say that from my experience I think it's made me a well-rounded physician.” Conclusion: The IMHO Fellowship is the first accreditated Integrative Hematology Oncology training program in the nation. We found the IMHO model an acceptable and desirable model of Integrative Oncology education. Our program revealed optimal timing of initiation is the PGY-4 year, incentive and productivity dashboards are needed for online learning productivity, and research productivity is contingent on robust mentorship and productivity milestones. Ongoing assessment is necessary to continue to optimize the IMHO fellowship model.

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.

INTRODUCTION Primary plasma cell leukemia (pPCL) is a rare and aggressive form of multiple myeloma (MM) with poor survival outcomes. Fluorescence in situ hybridization (FISH) evaluation is essential for the initial risk stratification in MM, and the presence of multiple high-risk (HR) cytogenetic abnormalities by FISH portends a worse prognosis in MM. We have previously observed that the presence of HR cytogenetic abnormalities by FISH at diagnosis is known to confer a poor overall survival (OS) in patients with pPCL. However, less is known about the cumulative effect of multiple HR cytogenetics abnormalities compared to a single HR cytogenetic abnormality on the OS outcomes of patients with pPCL. AIM To evaluate the prognostic implications of additive HR cytogenetics abnormalities by FISH in patients with pPCL treated with novel agents. METHODS We evaluated patients with newly diagnosed pPCL at the Mayo Clinic Comprehensive Cancer Center from 2014 - 2023 that received induction with novel agent combinations. pPCL was defined as patients meeting the diagnostic criteria for MM with 5% or more circulating plasma cells (cPCs) present on morphologic evaluation of their peripheral blood smear. HR cytogenetics abnormalities by FISH was defined by the presence of any one of the following: 1q gain/amplification, t(4;14), t(14;16), t(14;20), and del(17p). Time to next treatment (TTNT) and OS analysis were performed using the Kaplan-Meier method, and differences were assessed using the log-rank test. Statistical analyses were performed using the SAS biostatistical software JMP 17.0.1 (SAS Institute Inc). RESULTS We included 89 patients with newly diagnosed pPCL who received novel agents as first-line therapy between 2014 to 2023. The median follow-up was 45 months (95% CI: 35 - 65). At diagnosis, the median bone marrow plasma cell content was 80% (Range: 10 - 100), and the median cPC% on the peripheral smear was 21% (range: 5 - 85). There were 51 patients (59%) who had 20% or more cPCs on their peripheral smear. There was a preponderance of pPCL patients who had t(11; 14) as their primary cytogenetic abnormality (43%). The median lines of therapy received were 2 (Range: 1 - 9). There were 12 (13%) patients who received intensive induction therapy containing continuous infusional chemotherapy regimens at the onset of their diagnosis. Of the remaining patients, 35 (45%) were treated with a quadruplet (anti-CD38 antibody, proteasome inhibitor and immunomodulator), 24 (31%) with a triplet (proteasome inhibitor and immunomodulator) and 18 (23%) with a doublet (proteasome inhibitor only). The median OS for all pPCL patients in this cohort was 47 months (95% CI: 37 - 100). However, when stratified by cytogenetic risk, the median OS was 101 months (95% CI: 57 - NR) for those patients without any HR cytogenetic abnormalities (N = 24, 27%) vs. 37 months (95% CI: 22 - 63) for those with one or more HR cytogenetic abnormalities (N = 65, 73%) (P = 0.006). Of the patients with any HR cytogenetic abnormalities, 33 (36%) had one HR cytogenetic abnormalities and 32 (34%) had two or more HR cytogenetic abnormalities. The median OS for patients with one compared to two or more HR cytogenetic abnormalities were 47 (95% CI: 38 - 111), and 22 (95% CI: 17 - 37) months, respectively (P = 0.031). The median TTNT was 22 months (95% CI: 16 - 58) for those patients without any HR cytogenetic abnormalities vs. 16 months (95% CI: 9 - 21) for those with one or more HR cytogenetic abnormalities (P = 0.09). The median TTNT from the time of diagnosis for pPCL patients with one compared to two or more HR cytogenetic abnormalities were 18 (95% CI: 6 - 41) and 16 (95% CI: 10 - 19) months, respectively (p = 0.247). CONCLUSION Patients with pPCL with more than one HR cytogenetic abnormality had an inferior OS compared to those with only one HR cytogenetic abnormality, implicating the additive adverse effects of multiple HR cytogenetics abnormalities. In contrast, patients with pPCL without any HR cytogenetic abnormalities had a relatively long median OS (over 100 months).

Introduction: CAR-T (chimeric antigen receptor T-cell) therapy is known to be associated with immune-mediated toxicities including cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS). [18F]-Flurodeoxyglucose-positron emission tomography (FDG-PET) is frequently utilized for cancer staging before and after CAR-T therapy. Case series have demonstrated cerebral glucose hypometabolism (CGHM) on FDG-PET imaging in patients who developed CRS and ICANS. In this study, we aim to further characterize CART-CGHM. Methods: Patients who received CAR-T therapy at our institution from October 2019 to December 2023 were included. Clinical data was collected from retrospective review of the electronic medical record including patient age, sex, diagnosis, cancer stage, development of CRS or ICANS, and survival outcome. Standard of care whole body FDG-PET scans obtained before and approximately 30 days post CAR-T therapy were utilized. FDG-PET images of the brain were sub-selected and processed with dedicated imaging software (GE AW server 3.2 with Cortex ID, MIM Neuro, version 7.2.7). To identify CART-CGHM, visual and statistical comparison was made between the pre-CAR-T FDG-PET and the post-CAR-T FDG-PET using the age and gender matched normal cohort in the database as controls. Z-score changes > 1.5 were considered significant. Baseline variables were reported as frequency (%) and compared between patients with and without CGHM using Chi-squared test. Kaplan-Meier method was used to estimate the overall survival rate (OS) at different time points and log rank test was used to compare survival rates between the groups with and without CGHM. Multivariable Cox regression model was performed to evaluate the association between CGHM and OS with adjustment for ICANS. All tests were two-sided with p<0.05 considered statistically significant. Results: In total, 84 patients (41 women, 49%) were included. The median age at time of CAR-T therapy was 66 (33-85) years old. The most common diagnosis was multiple myeloma (n=39, 46%) followed by diffuse large B-cell lymphoma (n=33, 39%), follicular lymphoma (n=7, 8%), mantle cell lymphoma (n=3, 4%), and B-cell acute lymphoblastic leukemia (n=2, 2%). CART-CGHM was identified in 27 patients (32%). The pattern of CGHM was either global (n=15, 56%) or focal (n=12, 44%) with the prefrontal cortex predominantly affected. Of these 27 patients with CART-CGHM, 17 patients (63%) experienced ICANS and 23 patients (85%) experienced CRS. The diagnosis of lymphoma and development of ICANS were significantly associated with CGHM (p- 0.038 and <0.001 respectively). On univariate analysis, CGHM and ICANS were associated with negative impact on OS. The post-CAR-T 12-month OS for patients with CGHM was 76% versus 84% without CGHM (p-0.016), and 12-month OS for patients with ICANS was 64% versus 91% without ICANS (p-0.001). The post-CAR-T median OS for patients with CGHM, patients with ICANS, and patients with both CGHM and ICANS were 17.1 months, 13.5 months, and 12.6 months, respectively. On multivariate analysis, after adjusting for ICANS, CGHM alone did not have an impact on OS [HR 1.76 (0.71, 4.37); p-0.2250] but ICANS continued to have a negative impact on OS [HR 3.03 (1.21, 7.57); p-0.0178]. Conclusions: Our study represents the largest study to date on CART-CGHM. CART-CGHM was seen in 32% of CAR-T patients and had a strong association with ICANS and lymphoma patients. ICANS was found in 63% of CART-CGHM patients. ICANS alone or CGHM with ICANS were associated with a negative impact on OS. Although the underlying biological mechanism of CART-CGHM is not clear, it likely represents a significant immune-mediated reduction in cerebral glucose uptake. We suggest that CGHM represents a novel metabolic complication of CAR-T therapy and significantly contributes to CAR-T therapy associated neuro-cognitive toxicity. Although CART-CGHM can resolve completely, our study also showed patients with persistent CGHM on post-CART follow up FDG-PET scans. As such, CART-CGHM can potentially result in chronic neuro-cognitive complications. The current therapeutic interventions for CRS and ICANS do not appear to be adequately effective for CART-CGHM. Further research, involving multiple institutions, is urgently needed for better understanding of CART-CGHM and to develop specific therapeutic interventions.

NPM1 mutations (NPM1+) are found in about 30% of adult AML. While NPM1+ are generally associated with favorable risk, prior studies have shown that NPM1+ older patients, defined as ≥ 65 years, have significantly worse outcomes. The updated European Leukemia Net 2022 (ELN22) now classifies NPM1+ AML patients with FLT3-ITD (ITD+) and MDS-associated mutations (MDSm+) as adverse-risk, while NPM1+/ITD-/MDSm+ patients remain favorable-risk unless they have an adverse-risk karyotype. A recent report (Chan et al., Blood Adv 2024) found MDSm+ conferred worse OS only in patients ≥ 60 years; however another report (Othman et al., Blood 2024) did not find MDSm+ were significantly associated with adverse outcomes in a larger cohort of NPM1+ patients. To further assess this question, we examined the mutational landscape in a large cohort of pre-treatment, diagnostic specimens from 456 patients enrolled in SWOG clinical trials (SWOG-9031, SWOG-9333, S0106, and S0112) and 126 patients from the UW/FHCC Hematopoietic Repository (Total N=582). Patients were treated with curative intent as per standard practice or clinical trials. Out of the 582 patients, 191 were NPM1+ (33%), of which 148 patients had cytogenetic and long-term outcome data. Kaplan-Meier and cumulative incidence estimates were estimated. C-statistics and AUC for Cox, cause-specific and logistic regression models for overall survival (OS), event-free survival (EFS), time to relapse (TTR, calculated in n=106 who achieved complete remission [CR], death in remission analyzed as a competing risk) and CR were calculated for age, ELN17, and ELN22, as well as ELN17 and ELN22 adjusting for age. ELN17 favorable-risk patients reclassified as adverse-risk (N=5 of 108) demonstrated significantly shorter EFS (HR=2.50, p=0.05) and CR rate (OR=0.20, p=0.024), although with similar OS (HR 1.30, p=0.66) and TTR (HR=1.20, p=0.86). ELN17 favorable-risk patients reclassified as ELN22 intermediate-risk (N=23 of 108) did not show a significant difference in OS (HR 1.47, p=0.20), EFS (HR 1.35, p=0.12), CR rate (OR 0.75, p=0.46), or TTR (HR=1.64, p=0.11) compared to ELN22 favorable-risk. For ELN17 intermediate-risk (N=40), 5 patients were reclassified as ELN22 adverse-risk (12.5%) and had significantly shorter EFS (HR 2.89, p=0.037) compared to ELN22 intermediate risk, although there was not a significant difference in CR rate (OR 0.31, p=0.23) or OS (HR 0.81, p=0.67). We next compared the prognostic significance of age relative to ELN risk classification. Age was associated with higher C-statistics (OS=0.65, TTR=0.57 and EFS=0.60) and AUC (CR=0.64) compared to both ELN17 (OS=0.56, TTR=0.54, EFS=0.54, CR=0.54) or ELN22 (OS=0.57, TTR=0.57, EFS=0.57, CR=0.58). The combination of age and ELN22 resulted in the highest C-statistics for OS, TTR, and EFS (OS=0.68, TTR=0.60, EFS=0.64). To further assess the impact of MDSm on risk-stratification of NPM1+ AML, we performed multivariable analyses adjusting for FLT3-ITD, MDSm, and age in patients without adverse-risk disease. These analyses showed MDSm did not have a significant association with OS when controlling for age or FLT3-ITD. We also compared ELN22 favorable-risk patients with and without MDSm (MDSm+ N=18; MDSm- N=61). Compared with the MDSm-, there was a trend toward an inferior OS (HR 1.85, p=0.054) for MDSm+ patients but not EFS (HR 1.38, p=0.3) or TTR (HR 1.2, p=0.64). When stratified by age (<65, N=53 vs. ≥65, N=26), MDSm+ in younger patients did not show a difference for OS (HR 0.96, p=0.96), EFS (HR 0.63, p=0.53) or TTR (HR 0.4, p=0.37). Older ELN22 favorable-risk patients (≥65) had similarly poor OS (MDSm- HR 3.33 and MDSm+ 3.27, respectively, p=0.001 for both) and EFS (MDSm- HR 3.11 and MDSm+ 2.39, p=0.001 and 0.01) compared to younger MDSm- patients. In our study, the ELN22 guidelines incrementally improve risk stratification for EFS in NPM1+ patients. However, age remains the most prognostic factor, and patients ≥ 65 years have similar adverse clinical outcomes, whether classified as favorable risk by ELN17, ELN22, or incorporating MDSm. Moreover, MDSm do not confer a worse prognosis in NPM1+ patients when accounting for age or FLT3-ITD status. These findings differ from a recent report by Chan et al. and are in keeping with the report by Othman et al. Therefore, further understanding of the underlying biology of age and its effect on NPM1+ AML is needed to improve outcomes for older patients.

Introduction. Erdheim-Chester disease (ECD), Langerhans cell histiocytosis (LCH) and Rosai-Dorfman disease (RDD) belong to a group of histiocytic neoplasms often driven by mutations in the mitogen activated protein kinase (MAPK) pathway, most commonly in BRAF, MAP2K1 and K/NRAS. Currently, there are 2 drugs approved by the US Food and Drug Administration for the treatment of histiocytic neoplasms, cobimetinib and vemurafenib, both small molecule kinase inhibitors (SMKI) targeting mitogen-activated extracellular signal-regulated kinase (MEK) and BRAF, respectively. BRAF mutations are functionally classified as RAS-independent - either monomers (class I) or dimers (class II) - and RAS-dependent (class III). MAP2K1 mutations are functionally classified as RAF-independent, RAF-regulated, or RAF-dependent. Preclinical studies suggest class I, but not classes II-III, BRAF mutations are sensitive to RAF monomer inhibitors (dabrafenib, encorafenib, vemurafenib) while classes I-II, but not class III, BRAF mutations are sensitive to MEK inhibitors (Yaeger R, Cancer Discovery 2019). In contrast, RAF-regulated MAP2K1 mutants have variable sensitivities to allosteric MEK inhibitors (binimetinib, cobimetinib, selumetinib, trametinib) while RAF-dependent and RAF-independent MAP2K1 mutations are resistant. KRAS mutations are generally resistant to MEK inhibitors (Johnson C, Cancer Discovery 2022). Our study described the clinical efficacy of commercially available SMKIs in patients with histiocytic neoplasms harboring non-BRAFV600E mutations and compared the findings with preclinical data. Methods. We conducted a retrospective chart review of patients with histiocytic neoplasms who were treated with SMKI at Mayo Clinic. Only those who had adequate genomic testing and non-BRAFV600E mutations were included. Responses were categorized as complete (CR), partial (PR), or none (NR) based on established criteria. Results. We identified 31 non-BRAFV600E patients treated with SMKI (2 LCH; 20 ECD; 9 RDD). The median age at diagnosis was 61 years (range: 16-76) and 52% were females. The distribution of BRAF mutations was: class I (V600delinsRE [1]), class II (V495A [1], V471F [1], N486_P490del [2], GAB2-BRAF [1], UBR2-BRAF [1], RNF11-BRAF [1], UBTD2-BRAF [1]), and class III (G466E [1], D594A [1]). The only patient with class I mutation received cobimetinib and had PR. Among those with BRAF class II mutations, 2 received vemurafenib and had NR, while 9 received MEK inhibitors (binimetinib, cobimetinib, trametinib) and most responded (3 CRs, 5 PRs). The patient who had NR required dose reductions due to side effects. Both patients with class III mutation did not respond to cobimetinib. The median duration of responses was 19 months (range: 3+ to 45+) and 3 patients progressed subsequently. The distribution of MAP2K1 mutations was: RAF-independent (E102_103del [2]), RAF-regulated (I103N [1], K57T [1], Q56P [3], F53L [1], K57N [1]) and RAF-dependent (Y130C [1], D67N [1]). Both patients with RAF-independent mutations treated with cobimetinib had PRs. All patients with RAF-regulated mutations treated with allosteric MEK inhibitors responded (3 CRs, 5 PRs). Both patients with RAF-dependent mutations treated with cobimetinib responded (1 CR, 1 PR). The median duration of responses was 15 months (2 to 29+) with 3 patients progressing after treatment cessation due to intolerance. The distribution of RAS mutations was: NRAS (Q16R [1]) and KRAS (K117N [3], A146T [1], T581 [1], G13C [1], G12D [1]). Most patients treated with allosteric MEK inhibitors responded (3 CR, 4 PR, 1 NR). The median duration of response was 15 months (5 to 41) and 2 patients subsequently progressed, one of them after treatment cessation. Conclusions. Among patients with histiocytic neoplasms with non-BRAFV600E mutations receiving SMKI, our study found mixed patterns of concordance between pre-clinical predictions and clinical responses. There was concordance of efficacy in the setting of BRAF classes I-III and MAP2K1 RAF-regulated mutations. However, we found discordant findings in patients harboring RAF-dependent and RAF-independent MAP2K1 mutations as well as KRAS mutations as most responded to allosteric MEK inhibitors.