Positive Minimal Residual Disease Research Articles

MIR4435-2HG as a possible novel predictive biomarker of chemotherapy response and death in pediatric B-cell ALL.

Introduction: Although B-cell acute lymphoblastic leukemia (B-cell ALL) survival rates have improved in recent years, Hispanic children continue to have poorer survival rates. There are few tools available to identify at the time of diagnosis whether the patient will respond to induction therapy. Our goal was to identify predictive biomarkers of treatment response, which could also serve as prognostic biomarkers of death, by identifying methylated and differentially expressed genes between patients with positive minimal residual disease (MRD+) and negative minimal residual disease (MRD-). Methods: DNA and RNA were extracted from tumor blasts separated by immunomagnetic columns. Illumina MethlationEPIC and mRNA sequencing assays were performed on 13 bone marrows from Hispanic children with B-cell ALL. Partek Flow was used for transcript mapping and quantification, followed by differential expression analysis using DEseq2. DNA methylation analyses were performed with Partek Genomic Suite and Genome Studio. Gene expression and differential methylation were compared between patients with MRD-/- and MRD+/+ at the end of induction chemotherapy. Overexpressed and hypomethylated genes were selected and validated by RT-qPCR in samples of an independent validation cohort. The predictive ability of the genes was assessed by logistic regression. Survival and Cox regression analyses were performed to determine the association of genes with death. Results: DAPK1, BOC, CNKSR3, MIR4435-2HG, CTHRC1, NPDC1, SLC45A3, ITGA6, and ASCL2 were overexpressed and hypomethylated in MRD+/+ patients. Overexpression was also validated by RT-qPCR. DAPK1, BOC, ASCL2, and CNKSR3 can predict refractoriness, but MIR4435-2HG is the best predictor. Additionally, higher expression of MIR4435-2HG increases the probability of non-response, death, and the risk of death. Finally, MIR4435-2HG overexpression, together with MRD+, are associated with poorer survival, and together with overexpression of DAPK1 and ASCL2, it could improve the risk classification of patients with normal karyotype. Conclusion: MIR4435-2HG is a potential predictive biomarker of treatment response and death in children with B-cell ALL.

Real-world advantage and challenge of post-autologous stem cell transplantation MRD negativity in high-risk patients with double-hit multiple myeloma

BackgroundAutologous stem-cell transplantation (ASCT) remains a beneficial approach for patients with newly diagnosed multiple myeloma (NDMM) in the age of novel therapeutic agents. Nevertheless, limited real-world data is available to establish criteria for identifying high-risk ASCT patients.MethodsWe analyzed outcomes for 168 NDMM patients who underwent ASCT at our center from December 2015 to December 2022. We investigated the impact of the number of high-risk cytogenetics (HRCA), defined as t(4;14), t(14;16), 1q21 gain/amplification, and del(17p), as well as the post-ASCT minimal residual disease (MRD) status as prognostic indicators. We assessed progression-free survival (PFS) and overall survival (OS), and focused on identifying risk factors.ResultsThe cohort included 42% of patients (n = 71) with 0 HRCA, 42% (n = 71) with 1 HRCA, and 16% (n = 26) with ≥ 2 HRCA. After a median follow-up of 31 months, the median PFS was 53 months (95% CI, 37–69), and OS was not reached for the entire cohort. Despite similar rates of MRD-negativity post-ASCT, patients with ≥ 2 HRCA, termed “double hit” (DH), had a significantly higher risk of progression/mortality than those with 0 or 1 HRCA. Multivariate analysis highlighted DH (HR 4.103, 95% CI, 2.046–8.231) and MRD positivity post-ASCT (HR 6.557, 95% CI, 3.217–13.366) as adverse prognostic factors for PFS, with DH also linked to inferior OS. As anticipated, DH patients with post-ASCT MRD positivity displayed the poorest prognosis, with a median PFS of 7 months post-ASCT. Meanwhile, DH patients with MRD negativity post-ASCT showed improved prognosis, akin to MRD-negative non-DH patients. It is noteworthy to exercise caution, as DH patients who initially achieved MRD negativity experienced a 41% cumulative loss of that status within one year.ConclusionsThis study strongly advocates integrating DH genetic assessments for eligible ASCT patients and emphasizes the importance of ongoing MRD monitoring, as well as considering MRD-based treatment adaptation for those patients in real-world settings.

[Investigation of the immune profile of multiple myeloma patients achieving long-term survival after autologous stem cell transplantation].

Objective: To identify the characteristics of the bone marrow immune microenvironment associated with long-term survival in multiple myeloma (MM) patients. Methods: In the follow-up cohort of patients with newly diagnosed MM and who received "novel agent induction therapy and subsequent autologous stem cell transplantation and immunomodulator maintenance therapy" in the First Affiliated Hospital of Sun Yat-sen University, a cross-sectional study was carried out between August 2019 and May 2020. Using NanoString technology, the RNA expression of 770 bone marrow immune-related markers was compared between 16 patients who had progression-free survival ≥5 years and 5 patients with progressive disease. Among the 16 patients who achieved long-term survival, 9 achieved persistent minimal residual disease (MRD) negative while the other 7 had persistent positive MRD. The functional scores of each kind of immune cells were calculated based on the expression level of characteristic genes, so as to indirectly obtained the proportion of each immune cell subset. The Mann-Whitney U test and the Kruskal Wallis test were used for statistical analysis. Results: The proportion of neutrophils was significantly higher in long-surviving MM patients than in patients with progressive disease [functional scores, 13.61 (13.33, 14.25) vs. 12.93 (12.58, 13.38); Z=2.31, P=0.021]. Among long-surviving patients, those who were MRD-positive had a significantly greater number of mast cells compared with those who were MRD-negative [functional scores, 7.09 (6.49, 8.57) vs. 6.03 (5.18, 6.69); H=2.18, P=0.029]. Compared with patients with progressive disease, four genes (CTSG, IFIT2, S100B, and CHIT1) were significantly downregulated and six (C4B, TNFRSF17, CD70, IRF4, C2, and GAGE1) were upregulated in long-surviving patients. Among long-surviving patients, only gene CMA1 was significantly upgraded, 10 genes (ISG15, OAS3, MX1, IFIT2, DDX58, SIGLEC1, CXCL10, IL1RN, SERPING and TNFSF10) were significantly downregulated in the MRD-positive group compared with that in the MRD-negative group, the first 5 of which are related to the interferon response pathway. Conclusions: The increased neutrophil and mast cell numbers may be related to long-term survival in MM. Interferon signaling activation may be a key bone marrow immune profiling feature for MRD-negative, long-surviving patients with MM.

Abstract 5189: The potential of minimal residual disease (MRD) in guiding adjuvant therapy (AT) decisions in non-small cell lung cancer (NSCLC)

Abstract Background: Circulating tumor DNA (ctDNA)-based minimal residual disease (MRD) detection has become a strong prognostic stratification factor in post-operation non-small cell lung cancer (NSCLC). Here we sought to investigate the guiding potential of MRD in informing adjuvant therapy (AT) decisions. Methods: Patients with stage IA-IIIB NSCLC who had undergone confirmed R0 resection were enrolled. Blood samples were collected prospectively one month after surgery before initiation of AT (landmark) and longitudinally every 3-6 months since surgery. Postoperative AT was conducted according to the guideline recommendations and regular radiographical examinations were recommended for relapse surveillance. MRD detection was conducted via the MinerVa platform (Genecast Biotechnology Co., Ltd) using a tumor-informed strategy based on a fixed next-generation sequencing (NGS) panel spanning 769 cancer-related genes. Results: 168 patients were included in this study, with 11 (6.5%) experiencing confirmed relapse. Positive MRD was detected in 10.2% (16/157) of patients at landmark and was associated with a significantly higher risk of shorter disease-free survival (DFS)(HR: 26.2[6.7-102.7], P<0.001), irrespective of disease stage or gene alteration. Dynamic changes in ctDNA status further stratified patients into three subgroups with different prognosis. Consistent negative MRD detected at the landmark and all longitudinal timepoints represented the group with the best prognosis, while positive MRD detected at either the landmark or one subsequent timepoint showed a worse prognosis (Neg-Pos vs. Neg-Neg, HR: 37[3.2-438], P=0.004; Pos-Neg vs. Neg-Neg, HR: 14[1.2-172], P=0.035). The group with the worst prognosis occurred with consistent positive MRD (Pos-Pos vs. Neg-Neg, HR: 50[5.3-473], P<0.001). For patients with negative landmark MRD, there was no significant difference between the DFS of patients who received AT and those who didn’t(P=0.241), and the result was replicated in a highly controversial subgroup: stage I patients with high-risk factors (P=0.130). Besides, whether chemotherapy was applied before targeted therapy in the EGFR-mutant subgroup showed no influence on DFS provided that landmark MRD was negative (P=0.197). In multivariate analysis considering pathological high-risk factors, poor differentiation was identified as an independent risk factor for landmark MRD positivity (HR: 10.6[1.96-168.01], P=0.030). Conclusions: MRD is a strong and steady prognostic factor in post-operative NSCLC. AT may be waved for stage I patients with high-risk factors given that they had negative landmark MRD, same as the adjuvant chemotherapy before targeted therapy for patients with sensitive EGFR mutation. More attention should be paid to poorly differentiated tumors, indicative of a high-risk subgroup with potential residual diseases. Citation Format: Siyu Lei, Haiyan Xu, Yaning Yang, Linyan Tian, Ting Ma, Yan Wang. The potential of minimal residual disease (MRD) in guiding adjuvant therapy (AT) decisions in non-small cell lung cancer (NSCLC) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5189.

The value of minimal residual disease and IKZF1 deletion for predicting prognosis in adult patients with B-cell acute lymphoblastic leukemia

Objective: To reassess the prognostic value of minimal residual disease (MRD) and IKZF1 gene deletions in adults with B-cell acute lymphoblastic leukemia (B-ALL) who received pediatric-specific chemotherapy regimens during the Nanfang Hospital PDT-ALL-2016 trial. Methods: We retrospectively analyzed the prognosis of 149 adult patients with B-ALL who were admitted to Nanfang Hospital from January 2016 to September 2020. Prognostic factors were identified using Cox regression models. Results: The complete remission rate was 93.2% in 149 patients, with a 5-year overall survival (OS) rate of (54.3±5.0) % and a cumulative incidence of relapse (CIR) of (47.5±5.2) %. The Cox regression analysis revealed that MRD positivity at day 45 (MRD(3)) after induction therapy was independently associated with relapse risk (HR=2.535, 95%CI 1.122-5.728, P=0.025). Deletion of IKZF1 gene was independently associated with mortality risk (HR=1.869, 95%CI 1.034-3.379, P=0.039). Based on MRD(3) and IKZF1 gene status, we categorized adult patients with B-ALL into the low-risk (MRD(3)-negative and IKZF1 gene deletion-negative) and high-risk (MRD(3)-positive and/or IKZF1 gene wild type) groups. The 5-year OS and CIR rates were (45.5±6.0) % vs (69.4±8.6) % (P<0.001) and (61.6±8.3) % vs (25.5±6.5) % (P<0.001), respectively, in the high-risk and low-risk groups, respectively. The multivariate analysis showed that the high-risk group was an independent risk factor for OS (HR=3.937, 95%CI 1.975-7.850, P<0.001) and CIR (HR=4.037, 95%CI 2.095-7.778, P<0.001) . Conclusion: The combined use of MRD and IKZF1 gene in prognostic stratification can improve clinical outcome prediction in adult patients with B-ALL, helping to guide their treatment.

Outcomes and prognosis of haploidentical haematopoietic stem cell transplantation in children with FLT3-ITD mutated acute myeloid leukaemia.

The presence of internal tandem duplication mutations in the FMS-like tyrosine kinase 3 receptor (FLT3-ITD) is a poor prognostic predictor in paediatric patients with acute myeloid leukaemia (AML). We evaluated the treatment outcomes and prognostic factors of 45 paediatric patients with FLT3-ITD AML who achieved complete remission before haploidentical haematopoietic stem cell transplantation (haplo-HSCT) at our institution from 2012 to 2021. Among the 45 patients, the overall survival (OS), event‑free survival (EFS), and cumulative incidence of relapse (CIR) rates were 74.9% ± 6.6%, 64.1% ± 7.2%, and 31.4% ± 7.1%, respectively, with 48.8 months of median follow-up. Univariate and multivariate analyses associated positive minimal residual disease (MRD) at pre-HSCT and non-remission (NR) after introduce 1 with inferior long-term survival. The 100-day cumulative incidence of grade II-IV acute graft-versus-host disease (aGVHD) was 35.6% ± 5.2%, and that of grade III-IV aGVHD was 15.6% ± 3.0% The overall 4-year cumulative incidence of chronic graft-versus-host disease after transplantation was 35.7% ± 9.8%, respectively. In conclusion, haplo-HSCT may be a feasible strategy for paediatric patients with FLT3-ITD AML, and pre-HSCT MRD status and NR after introduce 1 significantly affected the outcomes.

Ixazomib, Lenalidomide, and Dexamethasone (IRD) Treatment with Cytogenetic Risk-Based Maintenance in Transplant-Eligible Myeloma: A Phase 2 Multicenter Study by the Nordic Myeloma Study Group.

Scarce data exist on double maintenance in transplant-eligible high-risk (HR) newly diagnosed multiple myeloma (NDMM) patients. This prospective phase 2 study enrolled 120 transplant-eligible NDMM patients. The treatment consisted of four cycles of ixazomib-lenalidomide-dexamethasone (IRD) induction plus autologous stem cell transplantation followed by IRD consolidation and cytogenetic risk-based maintenance therapy with lenalidomide + ixazomib (IR) for HR patients and lenalidomide (R) alone for NHR patients. The main endpoint of the study was undetectable minimal residual disease (MRD) with sensitivity of <10-5 by flow cytometry at any time, and other endpoints were progression-free survival (PFS) and overall survival (OS). We present the preplanned analysis after the last patient has been two years on maintenance. At any time during protocol treatment, 28% (34/120) had MRD < 10-5 at least once. At two years on maintenance, 66% of the patients in the HR group and 76% in the NHR group were progression-free (p = 0.395) and 36% (43/120) were CR or better, of which 42% (18/43) had undetectable flow MRD <10-5. Altogether 95% of the patients with sustained MRD <10-5, 82% of the patients who turned MRD-positive, and 61% of those with positive MRD had no disease progression at two years on maintenance (p < 0.001). To conclude, prolonged maintenance with all-oral ixazomib plus lenalidomide might improve PFS in HR patients.

Real-world prognostic significance of attaining minimal residual disease negativity in newly diagnosed multiple myeloma

The aim of the study was to evaluate the prognostic impact of minimal residual disease (MRD) in the real-world setting and the interaction between MRD and molecular risk, clinical response and autologous stem-cell transplant (ASCT). A retrospective analysis of 275 newly diagnosed multiple myeloma (NDMM) patients who achieved very good partial remission (VGPR) or better before maintenance were involved. We examined MRD status by multiparameter flow cytometry (MFC). At a median follow-up of 37 months (4–88 months), In patients who achieved ≥ VGPR, those with MRD negativity had significantly longer PFS (51 vs. 26 months; P < 0.001) and OS (Not reached: NR vs. 62 months, P < 0.001) than those with MRD positivity. MRD positivity was the independent prognostic factor for PFS with hazard ratios of 2.650 (95% CI 1.755–4.033, P < 0.001) and OS with hazard ratios of 2.122 (95% CI 1.155–3.899, P = 0.015). Achieving MRD negativity was able to ameliorate a poor prognosis associated with genetic high risk. MRD negativity was associated with better PFS regardless of ASCT treatment. MRD status was more predictable for clinical outcome than conventional clinical responses. Moreover, Sustained MRD negativity ≥ 12 or ≥ 24 months improved both PFS and OS. Patients with NDMM who achieved MRD-negative status or sustained MRD negativity had deep remission and improved clinical outcomes regardless of high-risk cytogenetics, ASCT and clinical responses in a real-world setting.

The prognosis of haploidentical hematopoietic stem cell transplantation in infants and patients under 3 years old with acute leukemia.

The role of allogeneic hematopoietic stem cell transplantation (allo-HSCT) in patients<3 years of age remains controversial. Data on haploidentical donor (HID) transplants in this age group is limited. We retrospectively analyzed the prognosis of 97 patients with acute leukemia aged<3 years who underwent HID transplantation at our institute. With a median follow-up of 45 months, the 3-year disease-free survival (DFS), overall survival (OS), and 3-year cumulative incidence rate of treatment-related mortality were 69.3% (95% confidence interval (CI): 59.9%-78.7%), 74.2% (95% CI: 65.2%-83.2%), and 3.6% (95% CI: 0.9%-9.7%) in all 97 patients, respectively. The 3-year DFS and OS rate in patients diagnosed<1 year and patients diagnosed ≥1 year were comparable: 77.8% (95% CI: 62.2%-93.4%) versus 66.3% (95% CI: 55.0%-77.6%, p=.253) and 82.5% (95% CI: 66.3-98.7%) versus 72.8% (95% CI: 61.9%-83.7%, p=.153), respectively. At the last follow-up, 23 patients had died, and 20 had died of relapse. Multivariate analysis revealed that positive pre-HSCT flow cytometric minimal residual disease (hazard ratio 5.605, p=.000) and AML-M7 expression (hazard ratio 2.906, p=.014) were independent adverse prognostic variables for relapse. HID transplantation is potent and safe for infants and young patients with acute leukemia. Relapse is the primary cause of treatment failure.

A randomized controlled trial of CAPEOX vs observation in patients with early-stage colorectal cancer with positive MRD after curative surgery (CAREME).

TPS225 Background: Most patients (pts) with early-stage colorectal cancer (CRC) have a good prognosis, but some still relapse shortly after surgery. Effective methods to assess the risk of recurrence in these pts and guide adjuvant chemotherapy (ACT) decision-making are lacking. Increasing studies have shown that circulating tumor DNA (ctDNA) can detect minimal residual disease (MRD) and identify pts with a high risk of recurrence. ACT could improve survival of MRD-positive pts with stage Ⅱ CRC suggested by recent studies, whether it is appropriate for those with stage Ⅰ or clinically low-risk stage Ⅱ CRC remains unknown. Methods: CAREME is a multicenter randomized controlled clinical trial aimed at investigating the benefit of chemotherapy for MRD-positive pts with early-stage CRC. Pts with resected stage Ⅰ or Ⅱ CRC will be evaluated by oncologists. Those who did not receive neoadjuvant therapy and are deemed suitable for active surveillance (i.e., ACT is not needed) will undergo a postoperative ctDNA test using MinerVa MRD assay (a tumor-informed assay covering 769 cancer-related genes). Pts with mismatch repair-deficient tumors will be excluded and stage Ⅱ pts should have no traditional high-risk features according to clinical practice guidelines. Pts with positive ctDNA (N = 38) will be equally randomized into two groups: treatment group (Arm A) or surveillance group (Arm B). Arm A will receive 8 cycles of CAPEOX therapy while pts in Arm B will not receive any ACT; both groups will undergo ctDNA tests at 6 months after randomization and be followed up every 3 months. The primary endpoint is 18-month recurrence-free survival, and a key secondary endpoint is ctDNA clearance at 6 months after randomization. Tumor samples from the pts will be collected for MRD assay and exploratory research. Accrual started in February 2023. Support: Genecast Biotechnology Company. Clinical trial information: NCT05699746 .

Prognostic value of minimal residual disease profiling in resectable hepatocellular carcinoma.

530 Background: Detecting post-surgical residual disease is a critical clinical requirement in resectable hepatocellular carcinoma (HCC). Previous studies focused on specific genomic regions have indicated that ctDNA holds promise as a tool for prognostic assessment. Nevertheless, these methods exhibited limited sensitivity and failed to meet the minimal residual disease (MRD) threshold. Here we report the prognostic value of MRD profiling in HCC patients who have undergone hepatectomy. Methods: This retrospective study involved 88 HCC patients who underwent surgical resections in China, from January to May in 2016. During surgery, tumor and normal tissue specimens were collected. Plasma samples were obtained 7 days post-surgery. PredicineBEACON, a baseline tissue- or blood-informed MRD assay, was used for MRD profiling. This entailed identifying tumor-specific mutations through whole exon sequencing of tissue samples. Subsequently, a personalized MRD panel, selecting up to 50 mutations via bioinformatics pipelines merged with a fixed panel featuring 500 tumor actionable hotspots, was created for each patient. To detect MRD in post-surgery plasma samples, we employed ultra-deep sequencing at a coverage of 100,000X, utilizing the designed panel. Results: In the cohort of 88 patients, the distribution based on Barcelona Clinic Liver Cancer (BCLC) staging was as follows: 79.5% stage A (N=70), 12.5% stage B (N=11), and 8.0% stage C (N=7,). The MRD assay identified 36 patients as MRD+ and 52 patients as MRD-. We observed significant correlations between MRD status and both relapse-free survival (RFS) and overall survival (OS). For MRD+ patients, the median RFS was 17.1 months, while it was not reached for MRD- patients (p=0.0013). Likewise, the median OS for MRD+ patients was 40.1 months, in contrast to it not being reached for MRD- patients (p=0.0012). The MRD positivity rate stood at 100% in stage C patients, a significantly higher percentage compared to the rates observed in stage B (36.4%, p=0.0256) and stage A (36.2%, p=0.0042). Significantly, MRD status emerged as a pivotal prognostic differentiator among clinically low-risk patients in stage A: among MRD+ patients, the median RFS was 23.3 months, whereas it was not reached for MRD- patients (p=0.05). Additionally, the median OS of both MRD+ and MRD- was not reached but their survival curves showed significant differences (p=0.038). Conclusions: This study demonstrated the clinical utility of ctDNA MRD assay in patients with resectable HCC, as notably evident in the robust detection of MRD using plasma samples collected 7 days after surgery. Furthermore, the assessment of post-surgical MRD status provided valuable prognostic insights into both patient survival and the risk of disease relapse. ctDNA MRD status played a pivotal role as a prognostic differentiator, particularly among clinically low-risk patients.

Abstract C092: T cell responses and clinical outcomes in pancreatic and colorectal cancer patients with minimal residual disease in AMPLIFY-201, a phase 1 trial of a first-in-class amphiphile lymph node targeted mutant KRAS vaccine

Abstract Background: Mutations in RAS occur in &amp;gt; 25% of solid tumors and &amp;gt; 90% of patients (pts) with PDAC and &amp;gt; 40% of pts with CRC. ELI-002 2P is a vaccine comprised of lymph-node targeted Amphiphile (Amph)-modified G12D and G12R mutant KRAS peptides together with an Amph-modified CpG oligonucleotide adjuvant designed to expand polyfunctional mutant KRAS-specific T cells. Interim phase 1 AMPLIFY-201 data (O’Reilly et al; ASCO, 2023, #2528) showed that adjuvant administration of ELI-002 was well-tolerated, with T cell responses in 87%, and tumor biomarker responses in 77% (a subset of 32% had ctDNA clearance). Here we report relapse free survival data and correlations between ELI-002 2P- induced T cell levels and outcomes in pts with PDAC and colorectal cancer (CRC) at high risk for relapse following locoregional treatment. Methods: Resected PDAC (n=20) and CRC (n=5) pts with tumors harboring KRAS G12D or G12R who had minimal residual disease positivity (MRD+) defined as elevated circulating tumor DNA (ctDNA) and/or serum tumor biomarker (CA19-9/CEA), received up to 6 priming doses and 4 booster doses separated by a 3-month rest period of subcutaneous ELI-002 2P vaccine monotherapy comprised of Amph-peptides (700 mcg each G12D/G12R), admixed with Amph-CpG-7909 at 0.1, 0.5, 2.5, 5.0 and 10.0 mg per cohort dose level. Primary endpoints included safety and recommended phase 2 dose (RP2D) of Amph-CPG-7909; secondary endpoints: biomarker reduction/clearance; exploratory endpoints: included relapse free survival (RFS) using immune Response Evaluation Criteria in Solid Tumors (iRECIST) and immunogenicity assessed by direct ex vivo Fluorospot and intracellular cytokine staining of peripheral blood mononuclear cells. Results: Direct ex vivo polyfunctional mKRAS-specific T cell responses to ELI-002 2P were observed in 20/23 (87%; 50% induced both CD4+ and CD8+ T cells, median 13-fold and mean 56-fold increase from baseline), with response in 9/9 (100%) pts treated at highest two dose levels including the 10 mg RP2D. Clinical efficacy correlated with T cell response in evaluable pts (n=22): median tumor biomarker reduction/clearance was -86.9% vs -4.5% in above vs below median T cell responders, respectively (p &amp;lt; 0.0124). At 25 weeks median follow-up, the median RFS was not reached compared to 17.1 weeks in above versus below median T cell responders (HR 0.11; 95% CI 0.027-0.446; p = 0.0108). The association of RFS with T cell response was not confounded by other baseline prognostic variables (including tumor stage, recovery from prior cytotoxic therapy as assessed by absolute neutrophil count, or immune system subsets such as %CD4+ or %CD8+of CD3+ lymphocytes). Conclusions: The association of ELI-002 2P vaccine T cell responses with clinical outcomes in a novel MRD+ trial design underscores the potential to reduce recurrence in the setting of microsatellite stable PDAC and CRC. A new phase 1/2 trial, AMPLIFY-7P (NCT05726864), is evaluating a new seven peptide (G12D, G12R, G12V, G12C, G12A, G12S, G13D) ELI-002 7P formulation. Citation Format: Zev A. Wainberg, Shubham Pant, Colin D. Weekes, Muhammad Furqan, Pashtoon M. Kasi, Craig E. Devoe, Alexis D. Leal, Vincent Chung, James R. Perry, Lochana Seenappa, Lisa K. McNeil, Esther Welkowsky, Peter C. DeMuth, Christopher M. Haqq, Eileen M. O'Reilly. T cell responses and clinical outcomes in pancreatic and colorectal cancer patients with minimal residual disease in AMPLIFY-201, a phase 1 trial of a first-in-class amphiphile lymph node targeted mutant KRAS vaccine [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr C092.

Intensified conditioning regimens with total marrow irradiation/etoposide/cyclophosphamide and busulfan/etoposide/cyclophosphamide overcome the impact of pre-transplant minimal residual disease on outcomes in high-risk acute lymphoblastic leukemia patients in complete remission.

Among high-risk acute lymphoblastic leukemia (ALL) patients undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT), those with positive minimal residual disease (MRD) are susceptible to poor outcomes. Therefore, it is necessary to determine the most suitable preparatory regimen for these patients. Data were analyzed from 141 patients who received allo-HSCT and were diagnosed with high-risk ALL. These patients underwent intensified conditioning regimens, including either total marrow and lymphoid irradiation (TMLI)-etoposide (VP16)-cyclophosphamide (CY) or busulfan (BU)-VP16-CY between October 2016 and November 2022. A total of 141 individuals were in complete remission (CR) before transplantation and, among all patients, 90 individuals exhibited a negative MRD status and 51 patients had a positive MRD status. In patients who tested negative for MRD, the incidence of relapse within a 2-year timeframe was 25.0% (24.8%-25.5%), compared with 32.2% (31.2%-33.2%) in MRD-positive patients; however, this difference was not statistically significant. There were no significant differences in the 2-year disease-free survival (DFS) and 2-year overall survival (OS) rates between the MRD-negative and MRD-positive groups (DFS: 67.2% (57.9%-78.1%) vs. 55.5% (42.6%-72.3%); OS: 69.0% (61.9%-88.2%) vs. 66.7% (53.9%-82.5%)). Furthermore, no notable variations were observed in the occurrence of transplant-related mortality (TRM) and graft-versus-host disease (GVHD) across the two groups. This study reveals the benefits of TMLI-VP16-CY and BU-VP16-CY conditioning regimens in high-risk ALL patients with CR and MRD-positive status. A large-scale prospective clinical trial is warranted in the future.

Combination of minimal residual disease on day 15 and copy number alterations results in BCR-ABL1-negative pediatric B-ALL: A powerful tool for prediction of induction failure

The current genomic abnormalities provide prognostic value in pediatric Acute Lymphoblastic Leukemia (ALL). Furthermore, Copy Number Alteration (CNA) has recently been used to improve the genetic risk stratification of patients. This study aimed to evaluate CNA profiles in BCR-ABL1-negative pediatric B-ALL patients and correlate the data with Minimal Residual Disease (MRD) results after induction therapy. We examined 82 bone marrow samples from pediatric BCR-ABL1-negative B-ALL using the MLPA method for the most common CNAs, including IKZF1, CDKN2A/B, PAX5, RB1, BTG1, ETV6, EBF1, JAK2, and PAR1 region. Subsequently, patients were followed-up by multiparameter Flow Cytometry for MRD (MFC-MRD) assessment on days 15 and 33 after induction. Data showed that 58.5 % of patients carried at least one gene deletion, whereas 41.7 % of them carried more than one gene deletion simultaneously. The most frequent gene deletions were CDKN2A/B, ETV6, and IKZF1 (30.5 %, 14.6 %, and 14.6 %, respectively), while the PAR1 region showed predominantly duplication (30.5 %). CDKN2A/B and IKZF1 were related to positive MRD results on day 15 (p = 0.003 and p = 0.007, respectively). The simultaneous presence of more than one deletion was significantly associated with high induction failure (p = 0.001). Also, according to the CNA profile criteria, the CNA with poor risk (CNA-PR) profile was statistically associated with older age and positive MRD results on day 15 (p = 0.014 and p = 0.013, respectively). According to our results, the combined use of CNAs with MRD results on day 15 can predict induction failure and be helpful in ameliorating B-ALL risk stratification and treatment approaches.

Sequential Imaging with Diffusion-Weighted Whole-Body MRI (DW-MRI) and PET-CT Identifies Patients at High Risk of Relapse in Multiple Myeloma

Introduction: Although the vast majority of patients with newly diagnosed multiple myeloma (NDMM) achieve deep responses during first-line therapy, most of them face relapse over time. Focal lesions, which are seen in up to 80% of NDMM, play a crucial role in MM evolution and can act as reservoirs for relapse disease. As a consequence, the combination of imaging- and minimal residual disease (MRD) negativity has been defined as a new response category. However, the dynamics and location of focal lesions during the treatment course remains poorly characterized and the answer to what imaging modality should be used to visualize focal residual disease remains elusive. In this study, we employed two techniques, PET-CT and DW-MRI, at multiple pre-defined time points to longitudinally track resistant lesions and investigate the combined prognostic value of these imaging modalities with other prognostic markers. Methods: We included 170 NDMM patients who were diagnosed between the years of 2010-2015 to ensure sufficient median follow-up time, which was 10 years. Median age of the study cohort was 60 years (range: 34-76), 104 were male (61%), and 31 patients (18%) had high-risk according to gene-expression profiles. All patients underwent PET-CT and DW-MRI evaluation at three pre-defined timepoints: baseline, post autologous stem-cell transplantation (ASCT) and at relapse. Minimal residual disease testing (MRD) by 8 color flow cytometry at a sensitivity level of 10 -5 post ASCT was available for 70 patients. Results: At baseline, 144/170 patients (85%) presented with focal lesions. Both imaging modalities, PET-CT and DW-MRI, showed positive results in 116 patients (68%). However, 21 patients (12%) had focal lesions detectable only by DW-MRI, while 7 patients (4%) showed focal lesions solely in PET-CT. After ASCT, only 12 patients had PET-CT positive lesions, whereas DW-MRI detected focal lesions in 53 patients, indicating a much higher detection rate with DW-MRI. Overall, 55 out of 170 patients (32%) showed residual lesions at this time point. The 26 patients w/o focal lesions in both PET-CT and DW-MRI at baseline remained negative post ASCT. Except for one patient, focal lesions after ASCT were persistent from initial diagnosis. Of note, two-thirds of the patients had residual focal lesions in the humeri and/or femora, which is surprising given that myeloma is considered a disease of the axial skeleton. Next, we correlated the presence of residual lesions with baseline patient characteristics, including age, gender, stage, and cytogenetic risk factors. Compared to patients w/o residual lesions, PET-positive patients showed an enrichment of rISS stage III (7 vs 50%, p&amp;lt;0.001) and deletion 17p (10 vs 33%, p=0.04). In contrast, patients who were DW-MRI positive only showed no significant association with any of the investigated variables. Both PET- and DW-MRI positive lesions post ASCT were associated with poor PFS (median 1.5 and 2.4 years, respectively vs. 9.4 years in imaging-negative patients, p&amp;lt;0.001) and OS (median 3.7 and 5.7 years, respectively vs. 11.3 years, p&amp;lt;0.001). Importantly, in a multivariate model the adverse prognostic effect of residual lesions was independent of baseline risk factors. To increase the power of the following combined imaging/MRD analysis, we defined an “Imaging+” group, which included the patients with PET+ and/or DW-MRI+ focal lesions. Among the 20 patients who achieved MRD-negative and imaging-negative status, an excellent PFS was observed, with only three events occurring in an 8-year follow-up. Residual lesions despite MRD negativity were only seen in two patients, and one of them progressed after 1.5 years. Dismal PFS was seen for double-positive patients (median 1.4 years), significantly worse compared to patients with MRD positivity only (8.9 years). Conclusion: Taken together, DW-MRI captures more patients with prognostically relevant residual focal lesions compared to PET-CT and should therefore be considered as a preferable imaging modality post ASCT. The high number of residual lesions in the extremities suggests a role of humeri and femora as reservoirs for treatment-resistant cells, deserving further investigation. For patients with MRD and imaging double positivity post ASCT, prognosis is dismal and alternate therapeutic approaches should be considered.

Prospective Evaluation of Minimal Residual Disease in Waldenström Macroglobulinemia across Different Tissues and Treatments: Results of the “BIO-WM” Trial of the Fondazione Italiana Linfomi (FIL)

Introduction. MYD88 L265P is the hallmark mutation in Waldenström Macroglobulinemia (WM) and is becoming increasingly important in the management of IgM-gammopathies, due to its role as prognostic and predictive biomarker. Recently, MYD88 L265P detection by allele-specific quantitative PCR was proposed as reliable minimal residual disease (MRD) marker in bone marrow (BM) samples (Varettoni, Hematol Oncol 2022). Novel, more sensitive, techniques as droplet digital PCR (ddPCR) might extend the feasibility of MRD detection in WM also in non-invasive tissues, as peripheral blood (PB) or plasmatic cell-free (cf) DNA. This was a secondary endpoint of the multicenter, observational “BIOWM” (NCT03521596) trial, sponsored by the Fondazione Italiana Linfomi (FIL) and the International WM Foundation/Leukemia and Lymphoma Society. From 2018 to 2020 this trial enrolled 300 consecutive patients with primary diagnosis of WM or IgM-MGUS and a systematic biobanking was performed. Here are presented the first results of the MRD study on the patient subset who received frontline treatment, with the aim of driving correlations with clinical response, type of therapy received and outcome prediction. Methods. Paired BM, PB and plasma samples were collected for each patient at baseline (T0) and follow-up and MYD88 L265P detection was performed by ddPCR in all specimens (Drandi, Haematologica 2018). As of today, 59/300 patients (58 WM and 1 IgM-MGUS) received frontline treatment and MRD levels after therapy (T2) were detected by ddPCR: actually, T0-T2 paired samples were available in 49 (BM), 56 (PB) and 48 (cfDNA) cases, respectively. Moreover, MRD was evaluated also by 8-color multiparametric flow cytometry (MFC) in 23 BM and 24 PB samples with a minimum of 10 million cells acquired. Results. Median age of the 59 treated patients was 68 years (24-85), 32% were female, median IgM value was 2420 mg/dL (101-8840), median Hb 10.5 g/dL (8 -17) and IPSS-WM was high in 35% and intermediate in 46%. MYD88 L265P mutation rate was 94% (46/49) in BM, 80% (45/56) in PB and 90% (43/48) in cfDNA samples, respectively. Treatment was started because of anemia in 32% cases, lymphadenopathy or splenomegaly in 34%, hyperviscosity in 20%, other reasons in 13%, and the only MGUS patient required treatment for anti-myelin-associated glycoprotein polyneuropathy. Thirty-one out of 59 patients received bendamustine-rituximab (BR), 23/59 dexamethasone, rituximab and cyclophosphamide (DRC) or DRC-like regimen and 5/59 a single agent therapy (namely, 3 rituximab, 1 cyclophosphamide, 1 ibrutinib). Overall response rate was 90% (87% for BR and 96% for DRC), with 19% CR, 29% VGPR and 35% PR in BR and 4% CR, 0% VGPR and 91% PR in DRC, respectively. Overall, MRD negativity after treatment was 30% (14/46) in BM, 89% (40/45) in PB and 54% (23/43) in cfDNA, respectively. Moreover, among patients still MRD positive after treatment, median MYD88 L265Ptumor burden shrinkage was about 2 Logs in BM (5.5E-03 vs 2.1E-01) and around 1 Log in cfDNA (5.9E-03 vs 3.7E-02) and in PB samples (3.6E-03 vs 2.5E-02), respectively (Figure 1). Interestingly, the MRD shrinkage in BM was deeper among patients receiving BR (48% MRD negative with a median MYD88 L265P decrease of more than 2 Logs among patients still MRD positive) vs patients receiving DRC (10% MRD negative with a median decrease of 1 Log), Figure 2. Similar trends in favor of BR in inducing MRD negativity were reported in PB (96% vs 88%) and cfDNA (70% vs 35%), respectively. MRD results by MFC were overall in line with ddPCR results: namely 27% of patients reached MRD negativity in BM and 69% in PB. The median follow-up for the whole series was 41 months, resulting in a 3-years PFS of 71% and 3-years OS of 89%, respectively. Interestingly, despite the current limited follow-up for such an indolent disease, MRD positivity by ddPCR in PB predicted a dismal clinical outcome if compared with MRD negative patients (3-years PFS 40% vs 73%, p=0.038). Conclusions. To the best of our knowledge, this is the first report of prospective MRD evaluation in a WM clinical trial. Our preliminary results suggest that MYD88 L265P monitoringby ddPCR is a suitable target for MRD analysis, in the contest of common immunochemotherapeutic schedules. Moreover, different levels of disease persistence were described across BM, PB and cfDNA, with MRD monitoring in non-invasive tissues showing promising predictive value for outcome discrimination.

GWAS Identifies Variants Associated with Minimal Residual Disease after Induction I in Pediatric Patients with Newly Diagnosed Acute Myeloid Leukemia

Acute myeloid leukemia (AML) patients' clinical outcomes are associated with genetic abnormalities present in leukemic blasts. However, the significance of common genetic variants with regards to variation in AML treatment outcome remains elusive. To that end, we conducted a genome wide association study (GWAS) on 400 pediatric patients diagnosed with de novo AML to identify single nucleotide polymorphisms (SNPs) that may be associated with minimal residual disease (MRD) after the initial induction chemotherapy. Integrating our top SNPs from GWAS results with matched AML-derived transcriptomic data, we performed an expression quantitative trait loci (eQTL) analysis to determine which variants may affect the expression of one or more genes. Array-based whole-genome genotyping with imputation was used to investigate SNPs for association with MRD outcome in 2 pediatric AML cohorts: the multi-site AML02 [NCT00136084, n=167] and AML08 [NCT00703820, n=233] trials. Genotype imputation was performed via TOPMED Imputation Server and yielded 6,741,200 SNPs. MRD positivity was defined as 1 or more leukemic cells per 1000 mononuclear bone-marrow cells. Association analysis with adjustment for ancestry was conducted using logistic regression to model MRD positivity with SNP as a predictor. Genome-wide significance level was set at Bonferroni-corrected P&amp;lt;5x10 -8 and a suggestive significance level of P&amp;lt;1x10 -4. For gene expression profiling, the mRNA expression levels for 137 patients were obtained at diagnosis using GeneChip Human Genome U133A array from patients in the AML02 cohort. For eQTL analysis, we evaluated the association of gene expression using a 500kb window surrounding the top SNPs identified in the GWAS using a linear regression model. A total of 92 SNPs reached the suggestive significance level but none passed the genome-wide threshold. Of the 92 SNPs, 10 SNPs were mapped to the Major Histocompatibility Complex, Class II, DP Alpha 1 gene (HLA-DPA1), with 8 of the 10 SNPs associated with an increased risk of MRD positivity. The top SNP in HLA-DPA1 is located in intron 1 with presence of the variant A allele conferring increased MRD positivity (OR=2.17, 95% CI (1.55-3.04), P=6.64x10 -6, Figure 1A). Of note, HLA-DPA1 SNP was not significantly associated with event free survival (EFS; HR: 1.21, 95% CI (0.95-1.56), P=0.13) or overall survival (OS; HR: 1.28, 95% CI (0.96-1.71), P=0.09), however the direction of association was consistent with the GWAS results. HLA-DPA1 is a protein coding gene and plays an integral role in the immune response by presenting peptides derived from extracellular proteins. HLA-DPA1 and several other MHC class II genes have shown to be downregulated in patients diagnosed with AML who experienced a relapse (PMID: 30380364). The eQTL analysis revealed a significant association with presence of the variant A associated with reduced mRNA expression of HLA-DPA1 (P=0.01, Figure 1B). In addition to the cis-eQTL association of our top SNP with HLA-DPA1 expression, significant associations were also observed with neighboring genes: HLA-DOA, HLA-DQA1, HLA-DQB1, and DAXX. Furthermore, when examining transcriptomic data for association with survival outcomes, we observed high HLA-DPA1 gene expression was significantly associated with favorable OS (HR: 0.46, 95%CI (0.23-0.91), P=0.025), though this association had similar direction it was not significant for association with EFS (HR: 0.68, 95% CI (0.39-1.18), P=0.169). Although limited by numbers, this study is one of the largest GWAS conducted in pediatric AML to identify common SNPs associated with MRD status after initial chemotherapy induction using an integrated genomic and transcriptomic validation approach. None of the SNPs reached genome-wide significant levels, however our top results show that genetic variation in several genes of biological relevance to have an impact on an early outcome endpoint. Moreover, we also have shown that our top SNP located in HLA-DPA1 gene is an eQTL and its mRNA expression is significantly associated with OS. Future studies are aimed at integrating other clinical endpoints such as EFS and OS with hope of creating a polygenic risk score to personalize treatment approaches. In addition, validation of these findings in larger cohorts of AML patients are warranted with future analyses to include known prognostic factors such cytogenetically defined risk.

One Tube 23 Color Full Spectral Flow Cytometry Panel in Detecting Minimal Residual Disease in Pediatric B-Cell Acute Lymphoblastic Leukemia

Introduction Minimal residual disease (MRD) is a normalized tool for risk stratification in the treatment of pediatric acute lymphoblastic leukemia (ALL) and has been introduced into many standardized chemotherapy regimens. Flow cytometry (FC) plays an important role in the monitoring of MRD. However, FC-MRD can't reliably detect residual leukemic cells below level of 0.01% in real clinical scenarios and some patients with negative MRD relapsed, suggesting the current used set of markers are not sensitive enough or specific enough. Published studies has shown that more markers with more reliable combination of antibodies may help improve the sensitivity and specificity of FC-MRD. Spectral multicolor flow cytometry (SMFC) has shown an advantage over traditional FC that more fluorescent markers could be applied simultaneously and more complex marker combinations could be exploited to distinguish leukemic blasts from normal B cell precursors with high specificity. Here we designed a SMFC-based panel of 26 markers with 23 fluorescent colors in one tube to monitor B-ALL MRD. Method The one-tube 23-color panels was designed according to previously published studies and our clinical experience based on standardized EuroFlow 8-color MRD panel. All the leukemia-associated immunophenotypes (LAIPs) were defined based on its deviation from hematogones. For CD10, CD19, CD22, CD34, CD58, CD73, CD86, CD123, CD200and CD304, the overexpression was considered as LAIP, while the under-expression was considered as LAIP for CD24, CD38, CD45 and CD81. Asynchronous co-expression of CD34 and CD20, CD34 and CD21 were also included. The aberrant cross-lineage expression was taken as LAIP for CD2, CD56, CD65, CD15, CD13, CD33, CD66c, NG2 and CD133. For CD44, under-expression or overexpression can both be considered as LAIP. To verify the effectiveness of the panel, 317 bone marrow samples from 317 patients with B-ALL diagnosed between 2009 to 2014 at the Shanghai Children's Medical Center (SCMC) were included. These samples were collected at day 19 to 283 (median: day 35), with 213 (67.19%) collected at around day 35, which was a regular time point to monitor MRD and to readjust the risk stratification. The results were compared with those of conventional 8-color FC-MRD. Results The limit of blank (LOB), limit of detection (LOD), and lower limit of quantitation (LLOQ) were firstly determined, the results showed reproducible sensitivity up to 0.001% (1-in-10 5) after acquisition of 4.8 million cells for 23-color panel. The 8-color and 23-color MRD panels showed high correlation of the quantitation of MRD (r 2=0.80, p&amp;lt;0.0001). Among cases of discordant between 8-color MRD negative (with cutoff &amp;lt;0.01%) and 23-color MRD negative (with cutoff &amp;lt;0.001%), relapse only occurred in patients with 23-color MRD positive and 8-color MRD negative, rather than patients with 23-color MRD negative and 8-color MRD positive, suggesting a higher sensitivity and specificity for 23-color MRD assay (See Figure). Patients with detectable MRD by either 8-color or 23-color had a significantly higher incidence of relapse (CIR, p&amp;lt;0.05) and shorter event free survival (EFS, p&amp;lt;0.05). Positive 23-color MRD seemed to be an even stronger factor impacting CIR and EFS. Compared to patients with 8-color MRD negative and 23-color MRD positive, patients with 8-color MRD positive and 23-color MRD negative had a significantly lower CIR (p&amp;lt;0.05) and a better EFS (p=0.068). Patients with positive 23-color MRD lower than 0.01% showed a trend towards poorer EFS and OS (p=0.083% and p=0.061%, respectively) compared to patients with 23-color MRD negative. Conclusion Based on these evidences, SMFC-based one-tube 23-color MRD panel for B-ALL was convenient and maneuverable with higher sensitivity and specificity compared to conventional 8-color FC-MRD panel. It would be a promising method to improve the risk stratification.

Zanubrutinib and Venetoclax As Initial Therapy for CLL/SLL with Obinutuzumab Triplet Consolidation in Patients with Minimal Residual Disease Positivity (BruVenG)

Background: Bruton's tyrosine kinase inhibitors (BTKi), anti-CD20 antibodies, and B cell lymphoma 2 inhibitors (BCL-2i) are essential therapeutic drug classes in the treatment of chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL). Clinical synergy of BTKi and BCL-2i combinations have been observed, which allow for an oral regimen, that can be safely administered in a clinic setting for most patients (Tam et al., 2022; Wierda et al., 2021). Still, it remains uncertain if anti-CD20 antibodies meaningfully add to the effectiveness of oral combination therapy. Recent reports of triplet regimens demonstrate modest improvement in minimal residual disease (MRD) negativity with similar response rates when compared to oral doublets (Davids et al., 2021; Soumerai et al., 2021; Wierda et al., 2021). Additionally, anti-CD20 antibody use causes significant B cell depletion resulting in prolonged immune suppression. Recent reports suggest BTKi use may in fact impair clinical activity of anti-CD20 antibodies, which can be mitigated by using selective BTKi and incorporating anti-CD20 later in the treatment course when lower disease burden is present (Da Roit et al., 2015; Flinsenberg et al., 2020; Pavlasova et al., 2016; Rawstron et al., 2018). Therefore, anti-CD20 therapy may not be required for all patients and could be optimized within a response-adapted strategy. This trial has been developed to assess efficacy and safety of a response adapted consolidative treatment approach utilizing obinutuzumab triplet consolidation in CLL/SLL patients who remain MRD positive after an oral doublet fixed duration treatment with zanubrutinib and venetoclax. This approach looks to maximize MRD negative remissions, spare toxicity by limiting anti-CD20 exposure, and provide a finite therapy. This study will utilize once daily zanubrutinib for which there is limited data in regard to safety and efficacy particularly in combination with venetoclax. Study Design and Endpoints: This is a single center, open label, phase II, investigator initiated clinical trial enrolling 50 subjects evaluating the efficacy and safety of zanubrutinib and venetoclax with obinutuzumab triplet consolidation in subjects who remain MRD positive (BruVenG). Eligible patients must have treatment naïve CLL/SLL and treatment indications per the International Workshop on CLL 2018 guidelines. Subjects with Richter's transformation are excluded. Treatment will consist of lead-in, combination, and consolidation phases. All subjects will be treated with a 3-cycle lead-in of 320mg oral, once daily zanubrutinib monotherapy. Venetoclax will be incorporated at cycle 4, per the standard prescriber insert ramp-up schedule. A final dose of 400mg oral, once daily venetoclax, in combination with 320mg oral, once daily zanubrutinib will be used in all subsequent cycles after ramp-up. At cycle 16, MRD will be assessed in the peripheral blood (PB) and bone marrow (BM) via clonoSEQ (Adaptive Biotechnologies). Subjects who are MRD negative (&amp;lt;1x10 -4 ) in both compartments will stop therapy. Subjects who are MRD positive in PB or BM will continue zanubrutinib and venetoclax for an additional 6 cycles. Obinutuzumab will be added to the oral doublet starting at cycle 17. Standard intravenous obinutuzumab lead-in will occur during cycle 17, followed by standard monthly intravenous dosing of 1000mg through cycle 22. Depending on MRD status, subjects will be treated for 16 or 22 cycles. All subjects who receive consolidation will stop treatment at cycle 23 regardless of end of treatment MRD status. The primary endpoint is cycle 16 PB and BM MRD negativity rates. A co-primary endpoint will be cycle 23 PB and BM MRD negativity rates in subjects who were MRD positive at C16 and who went on to receive at least 1 dose of obinutuzumab. Key secondary endpoints will include cycle 16 overall response rate, 36-month progression free survival, 36-month overall survival, 36-month time to next treatment, 24- and 36-month PB MRD negativity rates, tumor lysis risk reduction rates, and safety. Exploratory endpoints will assess the positive predicative value of the ∆400 biomarker (Soumerai et al., 2021) on MRD negativity at cycle 16. This biomarker will be assessed between cycle 4 and 6. The MRD negative rates at cycle 16 and cycle 23 will be estimated with a 90% confidence interval using the Clopper-Pearson method based on exact binomial distribution.

Blinatumomab Therapy for Low Level Minimal Residual Disease Detected By Next-Generation Sequencing in Adult B-Cell Acute Lymphoblastic Leukemia

Introduction: Blinatumomab, a bi-specific T-cell engager, has shown clinical benefit in patients with relapsed-refractory and hematologic complete remission with minimal residual disease (MRD)-positive Acute Lymphoblastic Leukemia (ALL). The BLAST trial (Gökbuget N et al., Blood. 2018) demonstrated improved overall survival (OS) and disease-free survival (DFS) in patients with MRD-positive disease (≥0.1%) who achieved MRD response with Blinatumomab. We sought to evaluate the utility of Blinatumomab in low levels of MRD (&amp;lt;0.1%) using clonoSEQ with a sensitivity of (0.0001%). Methods: Adult (18+) B- ALL patients that underwent treatment for B-cell ALL at Norris Comprehensive Cancer Center (NCCC) between 2016 and 2022 who had residual disease tracked using the Next Generation Sequencing (NGS)-based clonoSEQ assay (Adaptive Biotechnologies, Seattle, WA) were included. Patients who received Blinatumomab for MRD positivity were included only if they had a tracked clonoSEQ sequence within one month before starting treatment. Patients who didn't receive Blinatumomab were included if they had an MRD-positive clonoSEQ report. Those who were relapse/refractory when found to be MRD positive were excluded. Cumulative incidence of relapse (CIR) was evaluated using competing risk regression (Fine-Gray method), with death as a competing outcome. At the same time, OS and DFS were analyzed using Cox proportional hazards model. The start time was set to the date of the MRD report, and patients were censored until the last follow-up. Confounder-adjusted KM curves were calculated using direct standardization. Results: 47 patients were included with a median age at diagnosis of 45 years (range: 21-70). Most were Hispanic (N = 33, 70.2%), and the median follow-up time was 12 months. The 3-year OS, DFS, and CIR were 95.4% (95% CI 89.3-100%), 75.1% (95% CI 60.4-93.5%), and 20.3% (95% CI 7.2-38.0%). Twenty-six patients were treated with Blinatumomab (median two cycles, range 1-9), with most (N= 14, 53.8%) having low levels of MRD (&amp;lt;0.1%). Fourteen patients (53.8%) achieved MRD negativity with a median time to MRD negativity of 3.1 months. There were no relapses or death in patients who achieved MRD negativity in the treated group. However, non-responders with Blinatumomab had one death and two relapses. All patients continued Maintenance therapy after receiving Blinatumomab and did not proceed with the transplant. The patients who received Blinatumomab were more likely to be MRD positive on multiparameter flow cytometry (MFC) (60.0% vs. 28.6%, P = 0.042) but had a similar distribution of patient age, treatment type, and receipt of transplant. Additionally, there was a trend toward increased median percent residual cells on clonoSEQ (0.018% vs. 0.003% P =0.244) and flow (0.02% vs 0% P =0.066) in the Blinatumomab treatment group. On univariate analysis, significant predictors of CIR and DFS were flow percent (DFS: HR = 1.54; 95% CI 1.07-2.23; P = 0.019; CIR: HR = 1.83; 95% CI 1.38-2.41; P&amp;lt;0.001) and clonoSEQ residual cell count(DFS: HR = 1.58; 95% CI 1.04-2.41; P = 0.031, CIR: HR = 1.88; 95% CI 1.18-2.97 P=0.008). When controlling for the number of residual cells on close, patients who received Blinatumomab had significantly better CIR(HR = 0.11; 95% CI 0.02-0.69; P = 0.019) and a trend towards improved DFS(HR = 0.21; 95% CI 0.04-1.28; P = 0.092), but no difference in OS. On subgroup analysis of the 31 patients with low levels of MRD (&amp;lt;0.1%), there was no improvement in DFS for patients who were treated with Blinatumomab (HR = 0.41; 95% CI 0.04-3.91; P = 0.44). Of those with low levels of MRD, only two relapsed, and both did not receive Blinatumomab. Conclusions: In B cell ALL, Blinatumomab may offer a CIR benefit to patients with low levels of MRD as detected on clonoSEQ.