Allogeneic SCT Research Articles

AML-181 AML With Extramedullary Relapse After Allogeneic SCT Treated Successfully With Decitabine/Venetoclax: A Case Report

AML-181 AML With Extramedullary Relapse After Allogeneic SCT Treated Successfully With Decitabine/Venetoclax: A Case Report

AML With Extramedullary Relapse After Allogeneic SCT Treated Successfully With Decitabine/Venetoclax: A Case Report

AML With Extramedullary Relapse After Allogeneic SCT Treated Successfully With Decitabine/Venetoclax: A Case Report

Graft-versus-host disease after autologous stem cell transplantation in a recipient who underwent allogeneic stem cell transplantation 20 years earlier.

A literature review does not provide information about the safety of autologous hematopoietic stem cell transplantation (HSCT) in a recipient who has previously received allogeneic HSCT. We treated a 69-year-old woman with diffuse large B cell lymphoma. The patient received autologous stem cell transplantation (ASCT) in the second complete remission of malignant lymphoma. The patient had undergone allogeneic hematopoietic SCT (allo-HSCT) for chronic myeloid leukemia 20 years ago. Chronic myeloid leukemia had been in complete remission for the previous 20 years. Thus, the patient received autologous and allogenic HSCT 20 years apart. ASCT involves the patient receiving "self" hematopoietic cells from an allogeneic donor. In other words, this is immunologically the second allo-HSCT. The allo-HSCT 20 years ago was undergone by a related healthy brother, a human leukocyte antigen (HLA) 8/8 full matched donor. The conditioning regimen was reduced-intensity consisting of fludarabine and busulfan. The patient did not experience acute or chronic graft-versus-host disease (GVHD) after allo-HSCT. The second transplantation, ASCT was performed to the MEAM conditioning regimen. Engraftment was uneventful, and complete donor chimerism had been achieved even after ASCT. She suffered from an acute gastric mucosal lesion 52 days after ASCT. Pathological finding of gastric mucosa was nonspecific acute gastritis with significant neutrophil infiltration. Sex chromosome analysis of gastric mucosa demonstrated that mucosal cells had XX signals, whereas infiltrating neutrophils had XY signals. We speculated the patient onset of an acute gastric GVHD in this recipient after the second transplantation. This case remarked infiltration of neutrophils triggered GVHD reaction by resetting allogeneic immune reaction after the second transplantation. We describe a rare occurrence of GVHD reaction in a recipient of ASCT following allo-HSCT.

Autophagy prevents graft failure during murine graft-versus-host disease

AbstractAutophagy is an intracellular survival process that has established roles in the long-term survival and function of hematopoietic stem cells (HSC). We investigated the contribution of autophagy to HSC fitness during allogeneic transplantation and graft-versus-host disease (GVHD). We demonstrate in vitro that both tumor necrosis factor and IL-1β, major components of GVHD cytokine storm, synergistically promote autophagy in both HSC and their more mature hematopoietic progenitor cells (HPC). In vivo we demonstrate that autophagy is increased in donor HSC and HPC during GVHD. Competitive transplant experiments demonstrated that autophagy-deficient cells display reduced capacity to reconstitute the hematopoietic system compared to wild-type counterparts. In a major histocompatibility complex-mismatched model of GVHD and associated cytokine dysregulation, we demonstrate that autophagy-deficient HSC and progenitors fail to establish durable hematopoiesis, leading to primary graft failure and universal transplant related mortality. Using several different models, we confirm that autophagy activity is increased in early progenitor and HSC populations in the presence of T-cell–derived inflammatory cytokines and that these HSC populations require autophagy to survive. Thus, autophagy serves as a key survival mechanism in HSC and progenitor populations after allogeneic stem cell transplant and may represent a therapeutic target to prevent graft failure during GVHD.

Transplant-Associated Renal Thrombotic Microangiopathy after Allogeneic SCT

Transplant-Associated Renal Thrombotic Microangiopathy after Allogeneic SCT

Diagnostic management of blastic plasmacytoid dendritic cell neoplasm (BPDCN) in close interaction with therapeutic considerations

Blastic plasmacytoid dendritic cell neoplasm (BPDCN), a rare malignancy derived from plasmacytoid dendritic cells, can mimic both acute leukemia and aggressive T-cell lymphoma. Therapy of this highly aggressive hematological disease should be initiated as soon as possible, especially in light of novel targeted therapies that have become available. However, differential diagnosis of BPDCN remains challenging. This retrospective study aimed to highlight the challenges to timely diagnoses of BPDCN. We documented the diagnostic and clinical features of 43 BPDCN patients diagnosed at five academic hospitals from 2001–2022. The frequency of BPDCN diagnosis compared to AML was 1:197 cases. The median interval from the first documented clinical manifestation to diagnosis of BPDCN was 3 months. Skin (65%) followed by bone marrow (51%) and blood (45%) involvement represented the most common sites. Immunophenotyping revealed CD4 + , CD45 + , CD56 + , CD123 + , HLA-DR + , and TCL-1 + as the most common surface markers. Overall, 86% (e.g. CD33) and 83% (e.g., CD7) showed co-expression of myeloid and T-cell markers, respectively. In the median, we detected five genomic alterations per case including mutational subtypes typically involved in AML: DNA methylation (70%), signal transduction (46%), splicing factors (38%), chromatin modification (32%), transcription factors (32%), and RAS pathway (30%), respectively. The contribution of patients (30%) proceeding to any form of upfront stem cell transplantation (SCT; autologous or allogeneic) was almost equal resulting in beneficial overall survival rates in those undergoing allogeneic SCT (p = 0.0001). BPDCN is a rare and challenging entity sharing various typical characteristics of other hematological diseases. Comprehensive diagnostics should be initiated timely to ensure appropriate treatment strategies.

Age-Adapted Chemotherapy for Adults >40 Years Old with Philadelphia Chromosome Negative Acute Lymphoblastic Leukemia: Single Center Outcomes

Introduction: While pediatric-inspired regimens are preferred in younger adults with Ph-negative ALL, the optimal approach for treating adults age >40 with Ph-negative ALL has not yet been defined. In the U.S., hyperCVAD-based regimens are commonly used in this age group; however, hyperCVAD may be less effective than pediatric-inspired regimens in patients who are appropriate candidates for intensive therapy, and may be excessively toxic in patients who are poor candidates for intensive therapy. We explored giving two different multiagent chemotherapy regimens to adults age >40 with newly diagnosed Ph-negative ALL, depending on the individual patient's age and fitness level. Methods: At our institution starting in September 2020, patients between 40-60yo with good performance status received an intensive pediatric-inspired regimen based on the CALGB 10403 backbone, while patients >60yo (or 50-60 with poor PS) received a moderate-intensity multiagent chemotherapy backbone consisting of 2-part induction (induction-1: infusional doxorubicin/vincristine D1-4 + dexamethasone 40mg D1-4, 9-12, 17-20; induction-2: same as induction-1 plus cyclophosphamide 1000mg/m 2 on day 1) and consolidation with 6 cycles of chemotherapy, alternating between methotrexate (1g/m 2) plus peg-asparaginase (1,000U/m 2), and cytarabine (1g/m 2 x 6 doses). Prior to September 2020, patients in this age group received the hyperCVAD backbone. In both cohorts, patients not proceeding to allogeneic SCT in CR1 received POMP maintenance for up to 2 years. We reviewed charts of patients aged >40 with newly diagnosed Ph-negative ALL at University of Colorado Hospital from 2014-2023 to compare outcomes between patients treated before 09/2020 (“hyperCVAD” cohort) and after 09/2020 (“age-adapted” cohort). Results: Between 09/2020-04/2023, 17 adults with median age of 57 (range 40-81) with newly diagnosed Ph-negative ALL began treatment at our institution. 6 patients (age 40-56) received a modified pediatric-inspired regimen, and 11 patients (age 54-81) received a moderate-intensity regimen. 4 patients underwent allogeneic SCT in CR1 (including 1 for tMDS that developed during maintenance therapy). 3 patients received blinatumomab in CR1, 2 of whom subsequently received allo SCT. With a median follow-up of 16 months (range: 1-32 months), 1 patient relapsed during maintenance and 2 patients died from treatment-related mortality (1 during induction chemotherapy, 1 during salvage therapy for primary refractory disease). All three events occurred in patients who received the moderate-intensity regimen. Grade 3 or 4 asparaginase-related toxicities occurred in 2 patients (1 gr3 hyperbilirubinemia, 1 gr3 pancreatitis) and both resolved with supportive care. Between 2014-2020, 18 adults with median age of 58 (range 42-80) received hyperCVAD for newly diagnosed Ph- ALL. 6 patients received allogeneic SCT in CR1, and no patients received blinatumomab in CR1. With a median follow-up of 31 months (range: 7-94 months), 7 patients relapsed during consolidation or maintenance therapy and 3 relapsed after SCT. Among 10 patients who died during follow-up, 7 deaths were due to relapsed/refractory disease and 3 were due to treatment-related mortality (all 3 TRM were post-transplant). An improvement in relapse-free survival is seen in the cohort treated with age-adapted chemotherapy vs. the hyperCVAD cohort (p=0.045, log-rank test) (Figure 1), while there was no difference in overall survival (p=0.29) (not shown). Conclusions: Age-adapted multiagent chemotherapy is safe and effective in adults age >40 with Ph-negative ALL and may result in better outcomes than hyperCVAD. This is possibly due to better efficacy of pediatric-inspired chemotherapy for younger (40-60yo) patients and better tolerability of moderate-intensity chemotherapy for older (>60yo) patients, compared to hyperCVAD. Broad use of asparaginase in both the pediatric-inspired and moderate-intensity regimens may have also contributed to better outcomes in comparison to hyperCVAD. Incorporation of novel therapies in the frontline setting holds much promise to improve outcomes for older adults with Ph- ALL. Our observations suggest that the specific multi-agent chemotherapy regimen used, and in particular the incorporation of peg-asparaginase, may also affect outcomes significantly.

Inflammatory Memory Restrains Intestinal Stem Cell (ISC) Regeneration after Allogeneic Stem Cell Transplantation (SCT)

Introduction: Intestinal stem cells (ISCs) are responsible for the remarkable ability to maintain intestinal epithelium homeostasis and regeneration throughout life. Inflammatory damage of ISCs underpins injury caused by graft-versus-host disease (GVHD), inflammatory bowel diseases (IBD) and immune check-point blocker mediated colitis. However, it remains unknown whether the ISCs that survive or tolerate inflammation are fully functional and can return to their full functionality after the resolution of ongoing inflammatory insults. Herein we investigated the consequences of inflammation from GVHD on Lgr5+ISCs in multiple well-defined clinically relevant models of gastro-intestinal acute graft-versus-host disease (GI GVHD). Methods: We utilized single cell RNA (scRNA) sequencing to assess transcriptomics, Assay of transposase-accessible chromatin sequencing (ATAC-seq) to assess epigenomics, and functional metabolomics of ISCs in clinically relevant in vivo models of GVHD after major histocompatibility complex (MHC)-disparate BALB/c→C57BL/6 (B6) and MHC matched minor mismatched C3H.sw→B6 models of allogeneic SCT. Ex vivo intestinal organoids cultures, mitochondrial, and functional biochemical assays were utilized to determine the biological relevance of the changes observed from the ‘omic’ analyses and further validated them in vivo by developing novel Lgr5 +ISC specific succinate dehydrogenase A (SDHA) knock-out mice. Results: We examined the transcriptomes of Lgr5+ISCs with scRNA-seq of the intestinal crypts harvested from MHC-disparate BALB/c→B6 recipients on day +7 after allogeneic SCT. Bioinformatic analyses demonstrated upregulation of interferon and inflammation response genes but significant downregulation of genes involved in mitochondrial function, its complexes including complex II (SDH), ATP metabolic process, OXPHOS, and cytoplasmic translation. To assess the impact of metabolic functional gene changes, we harvested and assessed ISCs in ex vivo organoid cultures from transplanted recipients in the absence of ongoing inflammation. The ISCs harvested from GVHD animals demonstrated significantly reduced regeneration, differentiation and oxygen consumption rates (OCRs) with no change in extracellular acidification rates (ECAR) by Seahorse. FACs analysis confirmed reduction in SDHA component of mitochondrial complex II in Lgr5 +ISCs, demonstrating mechanistic cause for reduction in OXPHOS in ISCs. We next generated and utilized Lgr5 + ISC-specific SDHA KO mice as GVHD recipients and found that demonstrated significantly greater mortality when compared to the WT littermate recipients (P<0.01). Biochemical analyses demonstrated increased levels of succinate, a metabolic intermediary with known epigenetic and inflammatory functions, in ISCs harvested from GVHD animals. We therefore hypothesized that the reduction in ability to form functional organoids ex vivo, in the absence of ongoing inflammation, by the ISCs harvested from GVHD hosts is because of the inflammation epigenetic reprogramming induced by succinate mediated changes in DNA methylation (5-mC) of the ISCs in GVHD recipients. Consistent with the hypothesis greater DNA methylation, with alteration of epigenome by ATAC-seq was observed in ISCs sorted from GVHD recipients. Integrative analyses demonstrated correlation between epigenomic changes and transcriptomic changes. Finally, we analyzed whether the inflammation epigenomic induced changes in the GVHD ISCs with serial ex vivo organoid cultures and in vivo by transfer into secondary hosts. Both ex vivo and in vivo studies demonstrated poor regeneration from GVHD ISCs demonstrating retention of maladaptive memory in ISCs following their exposure to inflammation during GVHD. Conclusions: GI GVHD induced inflammation causes not only quantitative loss of ISCs but also induced qualitative changes in the surviving ISCs. Inflammation induced OXPHOS deficiency in Lgr5 + ISCs leads to accumulation of succinate that reprograms the epigenome and restrains their subsequent regeneration potential.

Tislelizumab, an Anti-PD1 Antibody, in Patients with Relapsed/Refractory Classical Hodgkin Lymphoma in Tirhol Bgb-A317-210: A Prospective Multicenter Lysa Phase 2 Study Conducted in Western Countries

Background: Programmed cell death protein 1 (PD-1) blockade is commonly used to treat relapsed/refractory (RR) classical Hodgkin lymphoma (cHL) but the overall response rates (ORR) and complete response rates (CRR) of approved anti-PD1 antibodies remain suboptimal. Tislelizumab blocks PD-1 with a high specificity and affinity and minimized FcγR binding on macrophages leads to reduced clearance. Results of the initial phase 2 study of tislelizumab in Chinese patients with RR cHL were impressive, with ORR and CRR of 87% and 63%, respectively, and 3-year progression free survival (PFS) of 40%, warranting further evaluation in a Western population with different standard of care, including more frequent use of autologous stem cell transplantation (ASCT) and targeted agents. Methods: TIRHOL (NCT04318080) is an international, prospective phase 2 study for patients with RR cHL conducted in France, Belgium, USA and Australia. Cohort 1 includes patients who previously underwent ASCT; cohort 2 includes patients who were ineligible for ASCT. Prior therapy with brentuximab vedotin (BV) was required in initial design; the protocol was amended to remove this criterion for both cohorts in October 2021. Tislelizumab 200 mg is given intravenously every 3 weeks until progressive disease (PD), unacceptable toxicity, or study withdrawal; tumor assessments are performed every 12 weeks. The primary endpoint is the ORR (best overall response of CR or partial response [PR]), as assessed by investigator, according to PET-CT International Lugano 2014 criteria. Null hypothesis is ORR = 45 % based on previous clinical trials and alternative hypothesis is ORR > 45%. Assuming the observed ORR = 65%, a sample size of 42 patients provides ≥ 80% power of at the one-sided 5% significance level. Secondary endpoints are CRR, time to response (TTR), duration of response (DOR), safety and tolerability of tislelizumab. Main exploratory endpoints are PFS and overall survival (OS). Results: Patients who received at least 1 dose of tislelizumab were included in the analysis. Between August 2020 and September 2022, 45 patients (14 in cohort 1 and 31 in cohort 2) were enrolled and dosed. At inclusion, the median age was 64 years (range 18-87), 67% were male and all had ECOG performance status 0-1; most patients had advanced stage disease (38% III, 42% IV), 11% had bulky disease, 18% had B symptoms and 29% had disease refractory to last therapy. The median prior lines of therapy received was 2 (1 - 4); 12 patients (27%) received ≥3 prior lines of therapy and 33 (73%) received prior BV. At last follow-up, the median number of tislelizumab doses (cycles) was 8 (1 - 33), corresponding to a median duration of treatment 24 weeks (range 3-105). The ORR was 64.4% (90% CI, 51% - 76%) with 14 (31%) patients achieving CR and 15 (33%) patients achieving PR (Figure 1). Remaining patients had stable disease (n=2, 4%), PD (n=13, 29%), or were not evaluated (n=1, 2%). The ORR was similar in cohort 1 (n=9/14, 64.3%) and cohort 2 (20/31, 64.5%). The median TTR was 2.69 months (range 0.3-5.6). The median DOR was 12.3 months (95% CI, 3 - NR) and was not reached for patients achieving CR. Three patients with objective response underwent subsequent ASCT (1) or allogeneic SCT (2). With a median follow-up of 11.4 months (95% CI, 6.7-13.5), the median PFS was 5.6 (95% CI, 5 - 14), 8, and 5 months for both cohorts combined, cohort 1, and 2, respectively. Thirteen patients with SUV increase meeting PD criteria but continued clinical benefit continued tislelizumab for a median of 3.6 months (range Q1:1.8 - Q3: 9.5) after PD. At last follow-up, 19 patients remain on tislelizumab and 11 (24%) have continued treatment for >1 year. The median OS was not reached with a 1-year OS rate of 93.5% (4 deaths; 95%CI, 75.0-98.5) and no treatment-related deaths. Grade ≥ 3 treatment emergent adverse events (TEAE) occurred in 15 (33%) patients, leading to discontinuation or interruption of tislelizumab in 9 and 2 patients, respectively. Immune-related (ir) AEs were observed in 15 (33%) patients and 3 patients had grade ≥ 3 irAEs (maculo-papular rash, hepatitis, hemolytic anemia). Conclusions: TIRHOL met its primary endpoint with an ORR of 64% and a CRR of 31% with an acceptable safety profile. This study confirmed that tislelizumab is a promising treatment option in cHL. Study follow-up is ongoing, but durable responses have been observed, especially in patients achieving CR.

Intestinal Geographical Pattern of Gut Microbiome and Metabolites Identifies Novel Regulators of Graft-Versus-Host Disease

Introduction: The severity of T cell-mediated gastrointestinal graft-versus-host disease (GI-GVHD) correlates with a decrease in the gut microbiome diversity, loss of obligate anaerobic bacteria and alterations in levels of salutary metabolites like short chain fatty acids (SCFAs). However, it is unknown whether the intestinal anatomic geography of the microbiome and its metabolites impacts GI GVHD severity. Herein, we investigate the pattern of the gut microbiome and metabolites from four distinct anatomical sites of intestines after allogeneic stem cell transplant (allo-SCT) via shotgun metagenomics and untargeted mass-spectrometry. Methods: To determine the composition of the gut microbiome and gut metabolites of mice after allo-SCT, we utilized contemporaneous analyses of shotgun metagenomic sequencing and untargeted mass spectrometry on the gut contents of mice 7 or 21 days after major histocompatibility complex (MHC)-disparate BALB/c→C57BL/6 (B6) allogeneic SCT. We investigated the microbial community composition and gut metabolites from four distinct gut locations (terminal ileum, cecum, transverse colon, descending colon) and performed integrative analysis to assess for novel pathways that may regulate GVHD biology. For shotgun metagenomics analyses, reads were depth normalized with BBnorm v.38.96 and assembled per-sample with MEGAHIT v.1.2.9. Prodigal v.2.6.3 was used to find genes in each bin. KofamScan v.1.3.0 was used to assign KEGG ortholog IDs (KO) to translated genes predicted by Prodigal. Community composition profiles were produced with Kraken2 v.2.1.2 and Bracken v.2.6.1. Functional profiles for each sample were determined with the Kraken community composition profiles and Humann3 v.3.0.0, with a GTDB database built with Struo2. Results: Consistent with previous reports from direct stool analyses, our data demonstrated that after allo-SCT, gut microbial diversity is reduced, relative abundance of obligate anaerobes decreases, and relative abundance of facultative anaerobes increases at all the intestinal anatomic sites, but the difference was maximal in ileo-cecal contents. Furthermore, metabolomic analyses reveal a decrease in previously described metabolites such as, SCFAs, bile acids and indoles at these sites. The distinct patterns of change between control and allogeneic samples depended not only on the gut location probed but also correlated with timepoint after transplant (7 days or 21 days) highlighting the importance of probing different gut locations and timepoints. The largest driver of differences between sample groups was (1) gut location (2) time after transplant (3) transplant type. Integrative analyses demonstrated loss of microbial functional genes related to butyrate processing following allo-SCT complementing previous studies that demonstrated reduction in butyrate levels. Further bioinformatic analyses identified novel microbial functional genes and metabolites that may have biological implications. Analyses revealed that after allo-SCT, phenyllactic acid (PLA) levels increased in the transverse colon and distal colon (fig.1). PLA is an anti-microbial compound and has been shown to have immune modulatory properties. Administration of PLA in drinking water of mice after allo-SCT worsened GVHD severity and increased mortality indicating PLA may play a role in inducing dysbiosis and worsening GVHD severity. Conclusion: Contemporaneous analyses of shotgun metagenomic and untargeted mass spectrometry of gut contents after allo-SCT reveal changes in microbial composition and metabolites consistent with previous data from analyses from stool. However, our analysis demonstrates distinct patterns of key metabolites and microbes in between syngeneic and allogeneic depending on gut location and time after transplant. Furthermore, our analyses have identified novel functional genes and metabolites that are implicated in GVHD severity.

CD19-Targeting CAR T-Cell Therapy in Transformed Waldenström Macroglobulinemia/Lymphoplasmacytic Lymphoma: A Descar-T and US Collaborative Study

Introduction: Patients with histological transformation (HT) of Waldenström macroglobulinemia (WM) who relapse or are refractory (R/R) have a poor prognosis with standard chemoimmunotherapy, notably patients who are unable to undergo high dose chemotherapy (HCT) and autologous stem cell transplantation (ASCT) or who relapse after HCT/ASCT. CD19-targeted chimeric antigen receptor (CAR) T-cell therapies can lead to durable responses in relapsed/refractory (R/R) diffuse large B-cell lymphoma (DLBCL) and thus may represent a promising therapeutic option in R/R transformed WM (tWM); however, data from pivotal trials is lacking. This study aimed to evaluate the efficacy and safety of anti-CD19 CAR T-cells in real-word patients with R/R tWM. Methods: We retrospectively identified patients with biopsy-proven transformed WM/lymphoplasmacytic lymphoma treated with axicabtagene ciloleucel (axi-cel) or tisagenlecleucel (tisa-cel) in the French DESCAR-T registry (NCT04328298) and 2 US centers. The primary endpoint was best complete response rate (CRR). Secondary outcomes were best overall response rate (ORR), progression-free survival (PFS), overall survival (OS) and safety. Responses were assessed according to the Lugano 2014 criteria at 1 month, 3 months and 6 months. Subsequent assessments were per institutional pratice. Cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS) were graded according to the ASTCT 2019 consensus criteria. Hematological toxicity and infections were graded according to the NCI CTCAE (version 5.0). Results: Between June 2017 and May 2023, 22 patients (18 from DECAR-T centers and 4 from US centers) with R/R tWM were treated with anti-CD19 CAR T-cells (13 axi-cel and 9 tisa-cel). Median age at WM diagnosis was 58 years (range 35-72). MYD88 L265P and CXCR4 mutations were present in 85% (11/13) and 29% (2/7) of patients with available data, respectively. Patients received a median of 1 prior line of treatment (range, 0-4) for WM and 2 prior lines (range, 1-4) for HT. Eight patients had received prior ASCT (2 for WM and 6 for HT) and 1 patient allogeneic SCT. The median time from WM to HT diagnosis was 4.5 years (range, 0-32) and 26 months (range, 3-90) from HT diagnosis to CAR T infusion. Of note, CNS involvement was present in 3 patients at DLBCL relapse before CAR T-cell therapy. At time of infusion, the median age was 66 years (range, 41-82) and 8 patients (36%) were older than 70 years. Median Eastern Cooperative Oncology Group (ECOG) was 1 (range, 0-2). Bridging therapy was administered to 16 patients (73%). Following bridging therapy, 6 patients had progressive disease (PD), 4 stable disease (SD) and 6 were responders (2 complete responses (CR) and 4 partial responses (PR)). After CAR T-cell infusion, best CRR was 82% and best ORR was 95%. The ORR/CRR was 95%/77% at 1 month, 76%/71% at 3 months and 68%/68% at 6 months. Seventeen patients (78%) experienced CRS, including 2 grade 3 (all after axi-cel), and 9 ICANS occurred (41%), including 1 grade 3 and 1 grade 4 (all after axi-cel). Eight patients (36%) presented infections, including 3 grade 3 and 1 grade 4. Neutropenia was reported in 78% (grade 3-4 = 68%), thrombocytopenia in 86% (grade 3-4 = 45%) and anemia in 86% (grade 3-4 = 32%) of patients. After a median follow-up of 17 months (range, 1-47), the 1-year PFS and OS were 70% and 84% respectively (figure). Five deaths were reported, 4 due to progressive disease and 1 from SARS-CoV-2 infection. Conclusion: This study shows a high efficacy of anti-CD19 CAR T-cell therapy in R/R tWM with no unexpected toxicity. Longer follow-up is needed to confirm the long-term efficacy of CAR T-cells in tWM.

Utilization and Barriers to Stem Cell Transplantation in Relapsed/Refractory Hodgkin Lymphoma: A ‘Real-World’ Study of Treatment Patterns and Outcomes at a Safety-Net Versus a Tertiary Academic Hospital

Background About 20-30% of patients with classical Hodgkin Lymphoma (cHL) develop relapsed or refractory disease (R/R) after initial induction therapy. The standard of care for R/R cHL involves salvage chemo- and/or immuno-therapy followed by autologous hematopoietic stem cell transplantation (ASCT), with which up to 50% of patients achieve durable remission. However, ASCT is not readily available for all patients. Safety-net hospitals disproportionately take care of minority patients who face significant barriers to care due to lack of insurance or prohibitive medical costs. With novel therapies like brentuximab vedotin (BV) and immune checkpoint inhibitors increasingly used in treating cHL, the optimal timing and role of ASCT in R/R cHL requires ongoing investigation. This study compares the demographics, treatment patterns, and survival outcomes among R/R cHL patients treated at a safety-net versus a tertiary academic institution. Methods We conducted an IRB approved, retrospective review of adult patients with cHL treated within our healthcare system between 2009 and 2023. Hypothesis testing was performed using Chi-square test or Fisher's exact test for categorical variables and t-test or Wilcoxon rank sum test for continuous variables, with a 2-tailed P value ≤ .05. Survival analysis for progression-free (PFS) and overall survival (OS) was performed using Kaplan-Meier method and evaluated by log-rank test. Univariate Cox proportional hazard regression was used to assess the relationship between pre-specified variables and the primary endpoints of PFS and OS. All statistical testing was done using R version 4.3.1. Results There was a total of 230 adult patients with cHL between the two hospital systems. Seventy-one patients (31%) in the study cohort had R/R cHL (safety-net hospital, n=30 [42%] and tertiary academic medical center, n=41 [58%]). Patients treated at the safety-net hospital were predominantly male (p=0.033), Hispanic (p=0.014) and uninsured (p<0.001) and had higher rates of HIV/AIDS (p<0.001). They also had more advanced stage disease (p=0.015), higher IPS score (p<0.001), and bone marrow involvement (p=0.031) (Table 1). Primary refractory cHL constituted 17/30 (57%) at the safety-net hospital and 22/41 (54%) at the academic medical center. Only 7/30 (23%) patients treated at the safety-net hospital received ASCT compared to 30/41 (73%) at the academic medical center (p<0.001). The main barriers to ASCT for the former were predominantly financial and social barriers (>50%) while those at the latter were based on patient/physician choice due to anticipated adverse effects and comorbid conditions. Following ASCT, 2/7 (29%) safety-net patients received BV maintenance therapy compared to 11/30 (37%) academic center patients. Rates of relapse post-ASCT were 29% (2/7) and 53% (16/30) respectively. Five patients (31%) at the academic center received allogeneic SCT at relapse post-ASCT. Univariate Cox regression analysis showed that advanced age at diagnosis and EBER positivity were associated with inferior OS (HR=1.043, p=0.004; HR=4.205, p=0.014) but not PFS (HR=1.004, p=0.699; HR=1.317, p=0.352). Higher IPS score and high ECOG performance status adversely impacted OS (HR=1.578, p=0.011; HR=10.280, p=0.025) and PFS (HR=1.261, p=0.016; HR=1.930, p=0.05). Receipt of SCT significantly improved OS (HR=0.211, p=0.016) and PFS (HR=0.333, p<0.001). This was reflected in the five-year OS of 90.2% versus 57.8% in patients receiving SCT versus those who did not. Notably, safety-net patients receiving ASCT (n=7) had a 5-year OS comparable to SCT recipients at the academic center (100.0% vs 87.7%) (Figure 1). Conclusions Our results show significant differences in treatment patterns and outcomes for R/R cHL patients at a safety-net versus a tertiary academic hospital. Even in the era of novel agents, ASCT significantly improves survival outcomes in R/R cHL. Thus, all eligible patients should be offered this curative treatment. In practice, however, socioeconomic barriers still pose significant barriers to optimal care, with less than 25% of safety-net patients having access to ASCT. Cost effectiveness may be another consideration as eligible patients barred from ASCT may need further treatment with expensive immunotherapies. Urgent policy measures are needed to mitigate these disparities experienced by safety-net hospitals.

Consolidation with Ponatinib Plus Sequential Blinatumomab and Chemotherapy after Low Intensity Dasatinib-Based Induction in Adults with Philadelphia Chromosome-Positive Acute Lymphoblastic Leukemia: Outcomes from a Single Institution

Introduction: Dasatinib plus prednisone is a standard induction approach for adults with Philadelphia Chromosome positive (Ph+) ALL known to result in high remission rates with minimal toxicity, however optimal post-remission therapy has not been determined. Given the excellent outcomes observed in recent clinical studies using ponatinib in adult Ph+ ALL, we explored a strategy of switching the TKI to ponatinib and consolidating with sequential blinatumomab (blina) and chemotherapy after dasatinib + prednisone induction. In contrast to recent studies of blina + TKI wherein patients have received up to 3-5 cycles of blina, we limited the number of blina cycles to 2 to minimize cost and logistical burden. We also administered systemic chemotherapy after blina with the goal of decreasing risk of extramedullary relapse, which has been observed in studies of blina-based “chemotherapy-free” regimens. Methods: Since June 2021, all adult patients with Ph+ ALL (n=14) at our institution were switched to ponatinib (30mg/d then 15mg/d once complete molecular remission [CMR] achieved) after dasatinib + prednisone induction. Concurrent with TKI, patients could also receive blina for one or two cycles (at discretion of treating clinician), followed by up to four cycles of consolidative chemotherapy alternating between high-dose methotrexate (1.5g/m 2) and intermediate-dose cytarabine (1g/m 2 x 6 doses). Patients not proceeding to stem cell transplant continue ponatinib monotherapy for up to 5 years, and 12 doses of intrathecal methotrexate 15mg are given throughout the total course of treatment. Prior to June 2021, our institutional approach was to recommend allogeneic SCT in CR1 for all transplant candidates immediately after dasatinib + prednisone induction. We reviewed charts of patients with newly diagnosed Ph+ ALL at University of Colorado Hospital from 2014-2023 to compare outcomes of patients treated before 06/2021 (“dasatinib/SCT” cohort) and after 06/2021 (“ponatinib” cohort). Results: From 6/2021-02/2023, 14 patients (median age 54) with newly diagnosed Ph+ ALL were switched to ponatinib after dasatinib + prednisone induction. After induction, 12 patients received blina (median 1 cycle; range 1-2) and consolidation chemotherapy (median 4 cycles; range 3-4). Blina could not be obtained for 2 patients who instead received chemotherapy only for 6 cycles. 3 patients (21%) underwent allogeneic SCT in CR1 due to persistent detectable bcr/abl transcripts by qPCR, and all 3 continued ponatinib as maintenance after SCT. With a median follow-up of 15 months (range: 4-24 months) no relapses have occurred and all patients remain alive at last follow-up. No patients have discontinued ponatinib due to intolerance. Chemotherapy plus ponatinib was well-tolerated after blina, with all except for one patient having received all intended cycles (one patient stopped chemotherapy after 3 cycles due to excessive hematologic toxicity). Between 11/2014-03/2021, 36 patients (median age 50) with Ph+ ALL were treated with dasatinib + prednisone induction, after which 31 (86%) underwent allogeneic SCT in CR1. All non-transplant candidates continued TKI alone. With a median follow-up of 37 months (range: 4-102 months), 11 relapses have occurred, 9 of which occurred after SCT. Among 13 patients who died during follow-up, 7 deaths were due to relapsed/refractory ALL and 6 were due to treatment-related mortality. Comparing outcomes between the two cohorts, relapse-free survival is improved in the more recent (ponatinib) cohort compared to the earlier (dasatinib/SCT) cohort (p=0.044, log-rank test) (Figure 1) despite a lower rate of allogeneic SCT in CR1 (21% vs 86%). No difference in overall survival (p=0.12) has been observed (not shown). Conclusions: For adults with Ph+ ALL, switching to ponatinib after dasatinib-based induction and consolidating with blina and chemotherapy is a safe and potentially effective strategy. The optimal number of blina cycles given post-remission is unclear, though we observed favorable outcomes in patients receiving a median of only 1 cycle, and maximum of 2 cycles. Favorable outcomes despite the low rate of allogeneic SCT (21%) seen in our cohort suggest that SCT may be safely avoided for some patients who receive ponatinib plus blina and chemotherapy-based consolidation.

Results of the Astral Study: A Prospective Phase II Clinical Study of the German Lymphoma Alliance to Assess the Efficacy and Toxicity of High-Dose Chemotherapy Followed By Allogeneic Stem Cell Transplantation As Treatment of Primary Progressive and Relapsed Aggressive Non-Hodgkin Lymphoma

Introduction Patients with relapsed and refractory (r/r) aggressive B- or T-cell lymphoma have a dismal prognosis. Registry analyses as well as one preceding prospective clinical study demonstrated durable disease control through graft-versus-lymphoma activity conferred by allogeneic stem cell transplantation (alloSCT) in this population and suggests this modality being a preferred treatment option after failing of less toxic approaches. Recently, allogeneic SCT has been shown to result in long term PFS in r/r large B-cell lymphoma (LBCL) with preceding CAR-T treatment. Despite the current achievements in treatment of r/r LBCL by introducing anti CD19 CAR-T as a treatment modality appproximately 60% need further approaches to achieve long term progression free survival (PFS). Here we represent the results of a prospective clinical trial of allogeneic SCT in r/r aggressive B- and T-cell lymphoma using a thiotepa based conditioning regimen. Methods ASTRAL is a national, multicenter, prospective phase II study of the German Lymphoma Alliance (GLA). Eligible were patients aged 18 or older with relapsed or primary progressive aggressive B- or T-cell lymphoma who had a fully matched (10/10) related or unrelated donor available. Patients underwent myeloablative conditioning regimen with Fludarabine 125 mg/m², Thiotepa 15 mg/kg and Cyclophosphamide 120 mg/kg (FTC). GVHD prophylaxis and posttransplant immunosuppression was done by local standards. The primary objective was to determine the efficacy and toxicity of the defined conditioning therapy followed by allogeneic stem cell transplantation. The primary endpoint was progression free survival at 1 year. Key secondary efficacy endpoints included rate of complete remissions (CR), rate of partial remissions (PR), overall response rate (OR), rate of progressive disease (PD), relapse rate, event free survival (EFS) and overall survival (OS) at 1 year and non-relapse mortality (NRM). Results From June 2019 until December 2021 in total 60 patients were enrolled. The demographic data are presented in table 1. The majority of patients (70%) had B-cell lymphomas. Patients had received a median of 3 prior lines (range 1-6), including autoSCT in 42% of all patients and CAR-T in 29% of the B-cell patients. The rate of primary progressive disease before salvage therapy was 27% (29% B-cell and 22% T-cell). 83% (50/60) still had measurable disease (no CR) prior to FTC, thereof 81% with B-cell (34/42) and 89% with T-cell lymphoma (16/18) and 13 (22%) had high intermediate and high IPI. After alloSCT, CR was achieved in 45% of patients with B-cell and in 67% with T-cell lymphoma, respectively. The overall response rate was 53%, 48% for B-cell lymphoma and 67% T-cell lymphoma. After a median observation time of 30 months, 1-year PFS was 40% [95%-CI: 28%-52%] (38% [23%-53%] (B-cell) vs. 44% [21%-67%] (T-cell) (figure 1). EFS was identical to PFS. After one year 15 patients (25%) had progressive disease or relapse, thereof 13 patients (29%) with B-cell lymphoma and two with T-cell lymphoma (11%). Thirty-seven patients died. Main cause of death was treatment related 19/37 (51%), including 8/19 deaths due to toxicity of the conditioning therapy (6 infections, 1 respiratory failure and 1 neurotoxicity). 12/37 (32%) patients died lymphoma related, 4/37 (11%) patients died of a SARS-Cov-2 infection, and two causes of death were unknown. 1-year OS was 43% [31%-56%] (40% [26%-55%] (B-cell) vs. 50% [27%-73%] (T-cell)). 1-year NRM was 35% [23%-47%] (31% [17%-45%] (B-cell) vs. 44% [20%-68%] (T-cell)). Most of the patients with grade 3-5 adverse events had infections 40/60 (67%), renal disorders 17/60 (28%) and oral mucositis 14/60 (23%). Conclusions This is the second prospective trial on alloSCT for r/r aggressive lymphoma ever performed, demonstrating that alloSCT can provide sustained disease control in heavily pretreated patients. Also in the modern era, including patients who failed CARTs the strong anti-lymphoma activity of allogeneic SCT is shown in the low relapse/progression rate and the long term PFS. FTC conditioning avoids the toxicities of busulfan-based regimens but fosters neuro- and other toxicities, especially when given at 15mg/kg. Still, NRM remains a challenge and warrants exploration of novel transplant strategies, such as modulation of conditioning intensity and GVHD prophylaxis, e. g. post-transplant cyclophosphamide.

Identification and Clinical Characterization of CNS Relapse in DLBCL Patients across 19 Prospective Phase 2 and 3 Trials - a GLA/ DSHNHL and LYSA Collaboration

Introduction: Depending on clinical and molecular risk factors, CNS relapse occurs in 1-15% of DLBCL patients (pts) and is associated with dismal outcomes. Despite its important role in further improving DLBCL therapy, a comprehensive and large-scale characterization of secondary CNS relapse remains challenging. Methods: We conducteda retrospective analysis of 7775 pts treated within 19 prospective German and French phase 2/3 trials to identify and characterize DLBCL pts with progression or relapse in the CNS. Pts with histology different from DLBCL (subtypes), not treated with anti-CD20 antibody, or displaying CNS involvement at diagnosis were excluded from the analysis. Results: Among 5289 eligible pts, 159 (3%) experienced progression or relapse in the CNS. Median age at diagnosis was 62 years (range: 19-80 years), 47% of pts were female. In 91% of all cases, reference pathology confirmed the diagnosis of DLBCL. At diagnosis, 28 pts (18%), 62 pts (39%), and 69 pts (43%) had a low (0-1 point), intermediate, and high CNS IPI (4-6 points), respectively. 133 pts received front-line therapy with R/O-CHOP, 19 pts with R-(Mega)CHOEP, and 7 pts with R/O-ACVBP. Following first-line therapy, 54% of pts achieved a CR/CRu. For 131 pts (82%), CNS progress/ relapse represented the first PFS event. Prior to the CNS event, salvage therapy was administered to 30 pts, including 11 pts treated with HDT/ASCT and one pt receiving allogeneic SCT. For 70 out of 158 pts (44%), CNS involvement was classified as intracerebral, 31% showed meningeal, and 3% intraspinal lymphoma involvement. In 22% of pts, CNS involvement was classified as combined including 5 cases with eye involvement. The CNS event occurred as progression without prior CR/ CRu of disease in 61 out of 159 pts (38%). For 155 pts it could be specified that 25% had an isolated progress in the CNS while 12% showed both CNS and concomitant systemic progress. 35% of pts showed an isolated CNS relapse while 28% suffered from a combined relapse. 82% of all CNS events occurred within the first two years after randomization while 29 pts (18%) experienced a late CNS event after 24 months. Notably, 46% of pts with low CNS IPI developed a late CNS event compared to 9% with high CNS IPI at diagnosis (Fisher exact, p<0.001). During the course of disease, 138 pts (87%) showed extranodal lymphoma involvement outside the CNS. The most frequently involved extranodal sites were bone (34%), gastro-intestinal tract (21%), soft-tissue (21%), kidney/ adrenal gland (20%), lung (19%), and liver (18%). In general, pts with CNS event had poor outcomes with a median OS of 3.4 months (95% CI 2.9-4.2) and a 2-year OS of only 15% (10-22%). While sex and initial (CNS) IPI had no impact on OS, we observed significantly worse OS for pts older than 70 years at diagnosis (log rank, p<0.001). OS was poor regardless of the site of CNS manifestation. Pts with isolated CNS disease demonstrated significantly better OS than pts with concomitant systemic involvement (p=0.023). Pts with CNS events occurring later than 24 months from randomization did not show improved OS compared to pts with early relapse/ progression (p=0.19). Treatment categories were reported for 150 pts. 95 pts received immunochemotherapy (IC), 30 pts in combination with radiotherapy (RT). More precisely, 69 pts received salvage therapies containing systemic MTX and 22 pts underwent consolidation with HDT/ASCT (73% of which had thiotepa-based conditioning regimens). Three pts received allogeneic SCT for consolidation. 28 pts were treated with RT alone (+/- intrathecal therapy (IT)). 27 pts received only IT, corticosteroids, or no treatment. Pts consolidated with HDT/ ASCT or allogeneic SCT had superior outcomes with a 3-year OS of 36% (20%-66%) compared to 18% (7.5%-44%) for pts receiving IC and RT, and to 9.7% (3.9%-24%) and 9.5% (2.8-32%) for pts treated with IC or RT alone, respectively ( Fig. 1). Overall, pts achieving a CR after CNS event (38/159, 24%) showed a 3-year OS of 52% (37-73%). Conclusions: This large study including more than 5000 DLBCL pts all treated on prospective clinical trials highlights the unmet medical need to improve the outcome of DLBCL pts suffering from CNS relapse. About one third of pts who underwent transplantation showed long-term survival in contrast to all other pts displaying very dismal outcomes. Novel strategies including targeted therapies and CAR T cells will have to challenge the survival rates reported here.

Patterns of Relapse in Patients with Acute Myeloid Leukemia (AML) Treated with Venetoclax-Containing Regimens

Background: Advances in next generation sequencing (NGS) technologies and better insight into the biology of acute myeloid leukemia (AML) have demonstrated the heterogeneity of the disease and its polyclonal nature at the time of diagnosis. While targeted therapies have improved remission rates and significantly improved outcomes, relapses are frequent and tend to arise from resistant sub-clones with genomic profiles and sensitivities that are often different from the dominant clone at initial diagnosis. While the use of targeted therapy at initial diagnosis may effectively control the dominant clone, the backbone chemotherapy in combination may be important in controlling the myriad of sub-clones that may be present. Methods: We hypothesized that the type of chemotherapy used in combination with the BCL2 inhibitor venetoclax (ven) may influence the pattern of relapses (including genomic profile) in patients with AML treated with different regimens. We retrospectively reviewed patients treated in three clinical trials of frontline ven in combination with chemotherapy-cladribine (clad) + LDAC + ven, CLIA + ven, and FLAG-IDA + ven-who had documented relapsed disease at any time. All patients had undergone karyotype and NGS based mutation testing at baseline and at time of relapse. We analyzed the baseline characteristics, karyotypes, and mutational profiles at baseline and at the time of relapse as well as outcomes of these patients. Results: We retrospectively reviewed 34 newly diagnosed patients who were treated on three prospective clinical trials including frontline ven and experienced a relapse: clad + LDAC + ven (N=19); CLIA + ven (N=7); and FLAG-IDA + ven (N=8). The median ages of these patients were 68 yrs (range, 57-80), 43 (23-61), and 39 (20-63), respectively. The median durations of response for these relapsing patients on each of the trials were 4.80, 8.05, and 7.61 months, respectively. 5.3%, 0%, and 75% of patients who relapsed from each of the three groups, respectively, had undergone prior allogeneic SCT. The baseline and relapsing mutation frequencies for the patients from each of the trials are summarized in Table 1. The most prevalent mutations present in patients who relapsed after frontline clad + LDAC + ven were TP53 (32%) and TET2 (26%); on CLIA + ven, DNMT3A (57%) and TET2 (43%); on FLAG-IDA + ven, TP53 (50%) and DNMT3A (38%). In the three cohorts, among all newly acquired mutations (n=41), the highest incidences were observed in RUNX1 (22%), DNMT3A (17%), TET2 (10%), and SMC3 (10%) (Table 1). The relapsed clad + LDAC + ven cohort developed the greatest variety of intermediate- and unfavorable-risk cytogenetic abnormalities upon relapse, and of the 42% of patients (n=8) with new abnormalities, -7/7q- was most frequently observed at 38% (n=3). Among all newly acquired cytogenetic abnormalities at relapse among the three cohorts, 55% (n=6) acquired -7/7q-, making this the most frequent cytogenetic abnormality acquired upon relapse in these patients. Conclusions: Among patients with relapsed AML after treatment with 3 frontline ven-containing regimens, we observed varying profiles. Mutational profiles exhibiting previously undetected aberrancies in RUNX1, DNMT3A, TET2, and SMC3 were most frequently observed at the time of relapse. Meanwhile, the most frequent karyotypic changes observed at the time of relapse were the acquisition -7/7q among patients, with the greatest number of acquisitions occurring among the clad + LDAC + ven cohort. Further analysis of the patterns of genomic changes at the time of relapse, including after treatment with hypomethylating agents and ven, can inform treatment decisions, maintenance strategies, and can improve patient outcomes

MRD Directed Treatment Intensification with Either FLAG-Ida or DA-Cladribine Improves Survival in Older AML Patients: Results from the NCRI AML18 Randomised Trial

Background Following intensive chemotherapy in acute myeloid leukemia (AML), residual disease, assessed by failure to achieve a remission (CR/CRi) or the presence of measurable residual disease (MRD) in remission identifies a poor risk group of patients. In the NCRI AML16 trial for older adults (>60yrs), patients who were MRD+ve by flow cytometry in their remission bone marrow after course 1 had significantly poorer survival (26% at 3yrs vs 42% if MRD-ve) due to a higher risk of relapse (Freeman et al JCO 2016). These results suggested that flow cytometric MRD after course 1, by identifying patients who have a poor outcome with standard therapy, could be used to risk stratify for further treatment. However, although not infrequently used, it is uncertain whether chemotherapy intensification is of benefit to older adults with residual disease. In the AML18 trial we therefore conducted a course 2 randomization to evaluate MRD directed chemotherapy intensification in older adults. Methods AML18 patients who did not achieve MRD negativity after their first course (either not in CR/CRi or MRD+ve or MRD unknown) were randomized to either continue treatment with up to two courses of standard DA (Daunorubicin, AraC) (DA3+8 followed by DA2+5) or to receive up to 2 courses of intensified chemotherapy:- either FLAG-Ida or DA with Cladribine (DAC) (DA3+8, followed by DA2+5 both including Cladribine 5 mg/m 2 x 5 days). Course 1 had comprised DA (3+10) with 0, 1 or 2 doses of gemtuzumab ozogamicin. FLAG-Ida was dose reduced for patients over 70yrs and in course 3 for all patients (Fludarabine from 30mg/m 2 days 1-5 to 25mg/m 2 days 1-4, Idarubicin from 8mg/m 2 days 3-5 to 5mg/m 2 days 2-4). The DAC randomization was closed May 2019 due to drug supply issues. The primary endpoint was overall survival (OS). Rate ratios (RR) were used when appropriate to account for non-proportional hazards effect. Secondary endpoints included conversion to MRD negativity (defined as undetectable MFC-MRD) following course 2. Results Between Nov 2014 and Jan 2023, 523 patients (median age 67yrs) entered this randomization (193 DA, 191 FLAG-Ida, 139 DAC) following course 1 response assessment. Of these patients 164 (31%) were not in CR/CRi, 260 (50%) were in CR/CRi MRD+ve and the remaining 99 (19%) were in CR/CRi but with MRD unknown (due to an absence of a leukaemia-associated-immunophenotype at diagnosis or inadequate/missing samples). 99/477 (21%) of patients had adverse risk cytogenetics. All characteristics were balanced between arms. Median follow-up was 51 months. Following course 2, 47% (78/164) of those not in CR/CRi after course 1 converted to CR/CRi within 50 days: 55%, 57%, 34% for DA, DAC and FLAG-Ida respectively (DA vs DAC P=0.63, DA vs FLAG P=0.015). Of 282 patients providing MRD results after both course 1 and 2, 51% (60/117), 63% (50/79) and 58% (50/86) converted to MRD negativity after DA, DAC and FLAG-Ida respectively (DA vs DAC P=0.16, DA vs FLAG P=0.33). Greater hematological toxicity was seen with DAC or FLAG-Ida compared to DA (P<.001 for both platelet and neutrophil recovery). Day 60 mortality was increased in patients randomized to FLAG-Ida (9% vs 4% with DA and 4% with DAC, P=0.032). In total, 213 (41%) patients underwent allogeneic SCT (DA 42%, DAC 47%, Flag-Ida 35%). OS at 5yrs was 27%, 32% and 32% for DA, DAC and Flag-Ida respectively (DAC vs DA HR=0.82 95%CI 0.62-1.09, P=0.174; FLAG-Ida vs DA HR=0.90 95%CI 0.70-1.16, P=0.407). In subgroup analyses, comparing patients with known and unknown MRD status, there was no detectable survival benefit from intensification for MRD unknown patients (FLAG-Ida vs DA RR 1.52 95%CI 0.92-2.50, P value = 0.105; DAC vs DA RR 1.10, 95%CI 0.81-1.45, P value = 0.549). In a sensitivity analysis, excluding patients with unknown MRD, there was a significant OS benefit for both DAC (OS at 5yrs, 32% vs 22% for DA; RR 0.84, 95%CI 0.77-0.98, P=0.029, Figure A) and FLAG-Ida (OS at 5yrs, 34% vs 23% for DA; RR 0.71, 95%CI 0.54-0.96, P=0.026, Figure B). Conclusion In older AML patients with evidence of residual disease following first induction, we saw a significant long-term survival benefit for intensified therapy with both DAC and FLAG-Ida in a randomized comparison with DA. This was despite early toxicity, observed particularly after FLAG-Ida. DAC intensification appeared better tolerated, delivered more patients to transplant and was associated with a greater conversion to MRD negativity.

Pirtobrutinib in Richter Transformation: Updated Efficacy and Safety Results with 18-Month Median Survival Follow-up from the Phase 1/2 BRUIN Study

Background:Richter transformation (RT) occurs in up to 10% of patients with chronic lymphocytic leukemia (CLL), typically presents as an aggressive diffuse large B-cell lymphoma (DLBCL) and is associated with poor survival. RT has no approved standard therapy; and clinical trial enrollment is the preferred first line of therapy. Pirtobrutinib, a highly selective, non-covalent (reversible) BTKi, that inhibits both wildtype and C481-mutant BTK with equal low nM potency, has favorable oral pharmacology that enables continuous BTK inhibition throughout the dosing interval. Pirtobrutinib demonstrated durable overall response rates (ORR) and was well tolerated in patients (pts) with poor-prognosis B-cell malignancies regardless of prior therapy. Here we provide updated safety and efficacy of pirtobrutinib in RT pts from the phase 1/2 BRUIN trial (NCT03740529). Methods: Pts with previously treated, histologically confirmed RT were eligible in the global, multicenter, phase 1/2 BRUIN study. Pts with untreated RT became eligible after Amendment 10. All but one patient received the recommended phase 2 dose of 200 mg daily. Key endpoints included investigator-assessed ORR, DoR per Lugano 2014 criteria, OS, and safety. A data cut of 05 May 2023 was utilized. To assess clonal relationship, IGH rearrangement studies were done on tissue biopsies with RT involvement, and baseline blood or bone marrow (BM) samples with CLL involvement. Results: Among all pts with RT (N=82) the median age was 67 (range, 26-95) and the median total number of lines of prior systemic therapy was 4 (range, 0-13). Pts with prior treatment had a median of 2 CLL-directed therapies and 2 RT-directed therapies. Eight pts did not have a previous line of RT-directed therapy, and 1 patient received neither RT- nor CLL-directed therapy. Common prior RT- and CLL-directed therapies (RT, CLL) included: chemotherapy (76%, 52%), cBTKi (34%, 62%), anti-CD20 antibody (78%, 66%), BCL2i (38%, 49%), stem cell transplant (SCT; 6%, 7%), and CAR-T (11%, 4%). Of 29 pts with bone marrow screening, 41.4% had CLL alone present in BM, 13.8% had DLBCL present and 24.1% had both CLL and DLBCL present. For 39 pts with available PET data, the median SUVmax was 19.1 (range, 2.6-41.2). For all 82 pts, the ORR was 50.0% (95% CI, 38.7-61.3) including complete (13.4%, n=11) and partial (36.6%, n=30) responses. For 61 pts who received prior cBTKi therapy, the ORR was 45.9% (95% CI 33.1-59.2). Among 28 pts with an RT-directed cBTKi and 51 pts with prior CLL-directed cBTKi, the ORR was 42.9% (95% CI, 24.5-62.8) and 43.1% (95% CI, 29.3-57.8), respectively. In 50 pts who discontinued prior cBTKi due to disease progression, the ORR was 42.0% (95% CI, 28.2-56.8). At median follow-up time of 9.7 months, the median DoR for all 82 RT pts was 7.4 months (95% CI, 3.1-19.1) and the estimated rate at 12 months was 45.9% (95% CI, 28.3-61.8). The median time on treatment for the 41pts who responded to treatment was 8.3 months. Eight pts stopped pirtobrutinib to pursue curative-intent allogeneic SCT and DoR was censored at the last preceding disease assessment. At a median survival follow-up of 18.3 months, the median OS for the entire RT cohort was 12.5 months (95% CI, 6.9-20.5). At 18 months, the OS rate was 44.3% (95% CI, 32.5-55.4). Frequent treatment-emergent adverse events (TEAE) in the RT cohort (n=82) were neutropenia/decreased neutrophil count (29.3%, n=24), fatigue (24.4%, n=20) and diarrhea, dyspnea, thrombocytopenia, and pyrexia (18.3% each, n=15). Common grade ≥3 TEAEs were neutropenia/decreased neutrophil count (23.2%, n=19), thrombocytopenia (11.0%, n=9), plus anemia and sepsis (9.8% each, n=8). Any grade hypertension (3.7%, n=3) or atrial fibrillation (1.2%, n=1) were infrequent. Three pts (3.7%) had treatment-related AEs leading to dose reductions, but no pt had a treatment-related AE leading to pirtobrutinib discontinuation. Analyses of clonality will be presented. Conclusions: Continued follow-up from BRUIN demonstrates encouraging response and OS in pts with RT. Pirtobrutinib remains well-tolerated with low rates of discontinuation and manageable safety profile. While RT remains a challenging diagnosis, pirtobrutinib represents a potential treatment option that warrants further investigation.

Dorsal Column Myelopathy Following Intrathecal Chemotherapy for Leukemia

Intrathecal (IT) methotrexate (Mtx) and/or cytarabine (AraC) improve CNS disease control in patients (pts) with hematologic malignancies. There are increasing number of case reports of irreversible, primarily dorsal column myelopathy in pts treated with IT chemotherapy. By describing the largest case series of myelopathy following IT chemotherapy, we aim to raise awareness about this devastating albeit rare complication. We retrospectively reviewed 25 pts with leukemia who developed paraplegia following IT chemotherapy between 2/2006 and 9/2021. Clinical/treatment characteristics, response, and toxicity were extracted from the medical records. Seventeen pts (68%) were male, 16 had B-cell ALL (64%), 4 had AML (16%), 2 had CML (8%), 2 had T-ALL (8%), and 1 had BPDCN (4%). The median age at diagnosis was 38 years (IQR 30-59). All pts required systemic salvage treatment after induction chemotherapy with a median number of 3 regimens received (IQR 2-5.5). In total, the median number of IT treatments was 19 per pt (IQR 14-27). Most pts (84%, n = 21) received single agent IT Mtx alternating with single agent AraC. Fifteen pts (60%) received triple IT therapy with a median of 3 treatments (IQR 0-8). Prior to the onset of myelopathy, 10 pts (40%) received allogeneic SCT and 9 pts (36%) were treated with radiation therapy. Median follow-up from diagnosis was 1.9 yrs (IQR 1.3-4.1). Myelopathy was progressive and irreversible in all pts (n = 25); 84% (n = 21) experienced sensory loss, and all pts had extremity weakness. Symptoms were ascending in 11 pts (44%) and descending in 4 pts (16%). Irreversible bowel/bladder incontinence developed in 12 pts (48%). CSF analysis at the time of symptom onset was negative for leukemia cells in most pts (n = 21, 84%) and showed malignant cells in 4 pts (16%). CSF studies showed elevated protein in 21 pts (84%). Myelin basic protein was elevated in all 13 assessed pts. On T2 weighted spinal MRI, all pts had enhancement of the dorsal columns, including 80% of pts with this dorsal column abnormality reported at the time of the study and 20% of pts (n = 5) with the dorsal enhancement noted retrospectively. Due to concern for occult disease, 20 pts (80%) received additional CNS-directed therapy after symptom onset. Twenty-two pts (88%) died at last follow-up. The time between neurological symptom onset and death was a median 3.5 months (IQR 2.6 and 5). Three pts (12%) are alive with paraplegia at a median of 4.4 years from symptom onset. Dorsal column myelopathy is a rare but devastating condition that can occur after IT chemotherapy in heavily pre-treated leukemia pts. T2 weighted spinal MRI can be helpful in the evaluation of pts that present with unexplained weakness and sensory changes. We recommend delaying additional CNS-directed therapy until work-up to rule out alternative etiologies is complete. Future strategies are desperately needed to address this irreversible treatment complication.

Targeting GD2 after allogeneic SCT: effector cell composition defines the optimal use of ch14.18 and the bispecific antibody construct NG-CU (GD2-CD3).

We investigated whether T cell-recruiting bispecific anti-CD3/GD2 antibody NG-CU might be an alternative to therapeutic anti-GD2 monoclonal antibody (mAb) ch14.18, mediating complement-dependent cytotoxicity (CDC) and antibody-dependent cell-mediated cytotoxicity (ADCC) through natural killer (NK) cells for immunotherapy in high-risk/relapsed neuroblastoma after autologous/allogeneic stem cell transplantation (auto/alloSCT). Different antibody concentrations and effector-to-target ratios (E:T) were evaluated using xCELLigence RTCA system, peripheral blood mononuclear cells (PBMCs) (healthy donors and patients after alloSCT), and neuroblastoma cell lines (LS/LAN-1). Mean specific lysis of LS cells utilizing PBMCs from healthy donors and ch14.18 (1µg/ml) was 40/66/75% after 12/24/48 h compared to 66/93/100% in the presence of NG-CU (100 ng/ml). NG-CU showed enhanced cytotoxicity compared to ch14.18, even at lower concentrations and E:T ratios, and completely eradicated LS cells after 72 h. To decipher the influence of effector cell subsets on lysis, different ratios of T and NK cells were tested. At a ratio of 1:1, ch14.18 was more effective than NG-CU. Using patient PBMCs taken at different time points posttransplant, significant lysis with both constructs was detectable depending on percentages and total numbers of T and NK cells; in the early posttransplant phase, NK cells were predominant and ch14.18 was superior, whereas later on, T cells represented the majority of immune cells and NG-CU was more effective. Our study highlights the importance of analyzing effector cell subsets in patients before initiating antibody-based therapy. Consequently, we propose an adjusted administration of both antibody constructs, considering the state of posttransplant immune recovery, to optimize anti-tumor activity.