Early Minimal Residual Disease Research Articles

Refining Risk Stratification for B-cell Precursor Adult Acute Lymphoblastic Leukemia Treated With a Pediatric-inspired Regimen by Combining IKZF1 Deletion and Minimal Residual Disease.

Minimal residual disease (MRD) is the most important prognostic factor for B-cell acute lymphoblastic leukemia (B-ALL) however nearly 20% to 30% of patients relapsed even when they achieved negative MRD, how to identify these patients is less addressed. In this study, we aimed to reassess the prognostic significance of MRD and IKZF1 in adult B-ALL patients receiving pediatric chemotherapy regimens. In the PDT-ALL-2016 cohort (NCT03564470), adult B-ALL patients were treated with a pediatric-inspired regimen; patients were redefined as standard (MRD-negative and IKZF1wild-type), intermediate (MRD-positive or IKZF1 deletion), and high-risk (MRD-positive and IKZF1 deletion) groups by combining IKZF1 deletion status and MRD. Furthermore, the prognostic panel of IKZF1 deletion and/or MRD-positive was confirmed in the independent cohort from the COG-P9906 dataset. In the high- and intermediate-risk groups, allogeneic hematopoietic stem cell transplantation (allo-HSCT) was strongly associated with higher 5-year overall survival (OS), higher leukemia-free survival (LFS), and lower cumulative incidence of relapse (CIR). In the standard-risk group, there was no significant advantage in the 5-year OS, LFS, and CIR of patients who received allo-HSCT versus those who received chemotherapy. Our study demonstrated that combining early MRD response and IKZF1 deletion allows for better risk stratification of patients to identify those who may benefit from allo-HSCT in the context of an intensified pediatric-inspired regimen.

Abstract A020: Enhanced cell-free RNA (cfRNA) recovery for liquid biopsy applications: Comparative analysis using controlled RNA samples for early and advanced cancer detection

Abstract Introduction: Extracting cfRNA from biological samples is crucial in liquid biopsy applications, particularly for detecting low-frequency mutations like KRAS G12V, essential for early cancer diagnosis and minimal residual disease (MRD) monitoring. Traditional cfRNA extraction methods involve multiple transfer steps, aliquoting, and pooling, leading to cfRNA loss and affecting mutation detection sensitivity and accuracy. The nRichDX Revolution cfTNA Max 20 kit, with its innovative nRicher cartridge, simplifies the extraction process by eliminating these extra steps, potentially enhancing yield and efficiency. This study evaluates the cfRNA recovery efficiency of the nRichDX kit compared to the Qiagen Circulating Total Nucleic Acid kit. Methods: Plasma samples (5 mL each) were spiked with RNA containing KRAS G12V mutation at concentrations ranging from 100 to 2 million copies, mimicking early-stage cancer detection and MRD monitoring, where low copy numbers represent early disease and high copy numbers reflect advanced cancer stages. cfRNA was extracted using the nRichDX and Qiagen kits, with each condition tested in triplicate. cfRNA recovery efficiency was assessed using quantitative reverse transcription PCR (qRT-PCR) to quantify KRAS G12V RNA copies recovered. High-sensitivity RNA ScreenTape Analysis was also used to evaluate cfRNA profile quality. Results: The nRichDX kit recovered significantly higher cfRNA yields than Qiagen across all concentrations. Recovery rates were consistent and reproducible, with over 70% of input RNA recovered, even at lower inputs (100 to 100,000 copies), where recovery rates were approximately 70-85%. High Sensitivity RNA ScreenTape Analysis showed a linear increase in 18S and 28S ribosomal peaks and high RNA Integrity Number (RIN) scores in nRichDX profiles. The ability to robustly recover low copy numbers is significant for early cancer detection and MRD monitoring. In contrast, the kit’s effectiveness in high copy number samples reflects its ability to monitor advanced cancer stages accurately. Conclusion: The nRichDX cfTNA kit demonstrates exceptional efficiency in cfRNA extraction from plasma samples across a broad dynamic range, from as few as 100 copies to as many as 2 million copies of the KRAS G12V mutation. Its versatility makes it suitable for various cancer detection and monitoring applications. The streamlined process offered by the nRicher cartridge minimizes sample handling and reduces cfRNA loss, enhancing performance. This translates to more accurate and sensitive detection of early-stage and high-burden mutations associated with advanced cancer. The high-quality profiles indicated by RNA ScreenTape Analysis further validate the reliability of the nRichDX kit, making it a valuable tool for liquid biopsy applications, with significant advantages in early cancer detection and monitoring disease progression. Citation Format: Nafiseh Jafari, Mayer Saidian, Jason Saenz, Andrew Dunnigan, Carlos Hernandez, Leila Aghili. Enhanced cell-free RNA (cfRNA) recovery for liquid biopsy applications: Comparative analysis using controlled RNA samples for early and advanced cancer detection [abstract]. In: Proceedings of the AACR Special Conference: Liquid Biopsy: From Discovery to Clinical Implementation; 2024 Nov 13-16; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2024;30(21_Suppl):Abstract nr A020.

Combination of Minimal Residual Disease By Flow Cytometry before and after Hematopoietic Stem Cell Transplantation Predicts Survival in Patients with Acute Myeloid Leukemia

Introduction: the measurement of the disease burden in patients with acute myeloid leukemia (AML) is one of the most important predictors of posttransplant (HSCT) survival. Patients with positive minimal residual disease (MRD) by multiparametric flow cytometry (MFC) or active disease (AD) before HSCT have dismal outcomes, but also the measurement in early postHSCT is a powerful tool to predict survival and the combination of both measurements can provide us with complementary information to identify high-risk patients. Aim: to analyse the influence of burden disease before HSCT (MRD negative, MRD positive or AD), the MRD in early postHSCT and the relation between both in terms of survival. Material and methods: we performed a retrospective analysis of 173 patients who received an allogeneic HSCT in the same centre between 2008 and 2023. All patients had an assessable bone marrow before HSCT (including patients in complete remission (CR) with valuable MRD by MFC or patients with AD) and/or at least one available MRD measurement among days +30 and +115 after HSCT. For MRD we use a cut-off of ≥0.1% to define MRD+. Overall survival (OS) and event-free survival (EFS) analysis were performed through Kaplan-Meier method. Cumulative incidence of relapse (CIR), and non-relapse mortality (NRM) were estimated using cumulative incidence method and differences were estimated using Gray´s method, considering each risk as a competing risk. P<0.05 was defined as statistically significant difference. Results: The median age of the cohort was 54 (range 45-61) years, and 58.4% were males. 31.2% of patients had secondary AML and 18.0% had favourable, 54.1% intermediate and 27.9% adverse risk by ELN2017 classification at diagnosis. Most patients (68.2%) were transplanted in first CR. The donor was sibling donor in 36.4%, haploidentical in 37% and unrelated in 26.6%. The conditioning intensity was myeloablative in 52.6%, 42.8% reduce intensity and 4.6% sequential conditioning. According to pre-HSCT disease, 160 patients had assessable bone marrow: 100 patients in CR with MRD-, 37 in CR with MRD+, and 23 with AD. The 3y-EFS was 58.5% in MRD- vs 31.5% in MRD+ vs 9.0% in AD patients (MRD- vs MRD+ p = 0.007; MRD- vs AD+ <0.001; MRD+ vs AD p = 0.012). The 3y-OS were 61.5% vs 47.0% vs 13.5% (MRD- vs MRD+ p = 0.048; MRD- vs AD p < 0.001; MRD+ vs AD p = 0.002). The 3y-CIR was 17.0% vs 49.0% vs 69.0% (p < 0.001). According to postHSCT, 151 patients had at least one assessable bone marrow aspiration with valuable MRD (posMRD) and without cytologic relapse, of those 136 had posMRD- and 15 posMRD+. The 3y-EFS was 52.0% vs 26.5% (p = 0.006) and 3y-OS 58.0% vs 28.0% (p = 0.015). The 3y-CIR was 30% in posMRD- and 60% in posMRD- (p = 0.003). Finally we evaluated patients with a valuable pretransplant aspirate and at least one aspirate after HSCT without haematological relapse and we divide patients among different groups: 1) patients with MRD-/MRD- (n=83), 2) patients with MRD+/MRD- (n=27), 3) patients with AD/MRD- (n=15) and finally 4) patients with MRD+ after HSCT regardless of the preHSCT status (posMRD+) (n=13). The 3y-EFS was 66.0% vs 40.5% vs 13.5% vs 23.0% comparing the four groups respectively (MRD-/MRD- vs MRD+/MRD- p = 0.014; MRD-/MRD- vs AD/MRD- p < 0.001; MRD-/MRD- vs posMRD+ p <0.001; MRD+/MRD- vs AD/MRD- p = 0.035; MRD+/MRD- vs posMRD+ p = 0.063; AD/MRD- vs pos MRD+ p = 0.957). The 3y-OS was 68.0% vs 56.0% vs 22.0% vs 23.0% (MRD-/MRD- vs MRD+/MRD- p = 0.08; MRD-/MRD- vs AD/MRD- p < 0.001; MRD-/MRD- vs posMRD+ p = 0.001; MRD+/MRD- vs AD/MRD- p = 0.013; MRD+/MRD- vs posMRD+ p = 0.041 and AD/MRD- vs pos MRD+ p = 0.803). The 3y-CIR was 17.0% in MRD-/MRD- vs 44.0% in MRD+/MRD- vs 65.0% in AD and 61.5% in posMRD+ respectively (p <0.001) Conclusions: preHSCT disease burden or early postHSCT MRD measurements are both prognostic factors of postHSCT survival, but the combination of both are more informative in our series. Patients with MRD+ and especially those with AD before HSCT, have adverse outcomes regardless they achieve early posMRD-. The prognosis of patients with posMRD+ was also dismal. Patients with posMRD+ in early HSCT and those with any residual disease before HSCT are high-risk patients for relapse in whom we must implement therapeutic strategies.

Early minimal residual disease eradication in light chain amyloidosis generates deeper and faster cardiac response

Minimal residual disease (MRD) is of growing interest in light chain (AL) amyloidosis and is associated with higher rates of cardiac response. A new graded cardiac response criteria has been proposed for better assessment of cardiac improvement. We evaluated MRD status in 63 patients with cardiac AL amyloidosis using next generation flow cytometry (sensitivity ≥ 1*10–5) within four cycles after treatment initiation and cardiac response kinetics. All patients were treated with first-line proteasome inhibitor (100%) and predominantly bortezomib (87.3%). The overall early MRD negative rates were 33.3%. Patients who achieved early MRD negativity were less likely to harbor t(11;14) (21.1% vs 57.5%, P = 0.009). The MRD negative rates amongst patients in hematologic complete response were 66.7% (14/21), and in very good partial response 29.2% (7/24). Early MRD negativity was associated with a higher likelihood of achieving ≥ cardiac partial response (≥ CarPR) (66.7% vs 38.1%, P = 0.032) and ≥ cardiac very good partial response (≥ CarVGPR) (38.1% vs 11.9%, P = 0.023) throughout first-line therapy. The cumulative incidence curve of achieving ≥ CarPR (P = 0.034) and ≥ CarVGPR (P = 0.026) showed significant difference between early MRD negative and positive group. After a median follow-up time of 27.2 months, the median progression free survival was longer in early MRD negative group (not reached vs 31.3 months, P = 0.033). Early MRD eradication in cardiac AL amyloidosis generated deeper and faster cardiac organ response.

A Novel Urine DNA Predictor for Noninvasive Early Diagnosis and Monitoring Minimal Residual Disease of Upper Tract Urothelial Carcinoma.

For early detection and postoperative monitoring of upper tract urothelial carcinoma (UTUC), the traditional detection method was limited to its invasiveness and insufficient sensitivity. We aim to use urine tumour DNA (utDNA) for detecting minimal residual disease (MRD), early diagnosis and perioperative monitoring in UTUC. We previously established a utDNA multidimensional bioinformatic valuation model, named utLIFE, using low-coverage whole-genome sequencing and targeted deep sequencing. This prospective cohort enrolled 93 patients diagnosed with UTUC without metastasis. We collected morning urine samples on the day of surgery and the discharge day after the operation for utLIFE testing. In addition, we also enrolled 80 healthy controls to further validate the specificity of the utLIFE model in the study. The utLIFE of preoperative samples could discriminate UTUC with high specificity (96.25%, 77/80), and high sensitivity (96.77%, 90/93) regardless of stage and grade. The sensitivity of utLIFE was significantly higher than urine cytology (p < 0.001) and fluorescence insitu hybridisation (FISH) (p < 0.001) (N = 19), especially in early-stage and low-grade UTUC. Postoperative utLIFE scores were significantly decreased compared with those of preoperative samples (79 vs. 36, p < 0.001), indicating its association with tumour burden. For special pathology types, utLIFE performed less well in sensitivity and perioperative alteration. In conclusion, we established a bioinformatic utDNA valuation model, utLIFE, which was validated to be a rapid and noninvasive approach with high sensitivity for early detection and MRD monitoring for UTUC.

Association between Early Minimal Residual Disease Detected by Flow Cytometry and Prognosis in Children with Acute Myeloid Leukemia: A Clinical Retrospective Study

To investigate the prognostic value of minimal residual disease (MRD) detected by multi-parameter flow cytometry (MFC) in pediatric patients with acute myeloid leukemia (AML) after induction chemotherapy. A retrospective study was conducted on 97 pediatric patients initially diagnosed with AML at Wuhan Children's Hospital from August 2015 to December 2022. The study analyzed the results of MRD detection using MFC after the first and second cycles of induction chemotherapy, and its association with prognosis were analyzed. Following the first cycle of induction treatment, 57 of the 97 patients tested positive for MRD (MRD1+ , 58.8%). Subsequently, 19 patients remained MRD positive (MRD2+ , 19.6%) after the second cycle of induction treatment. Kaplan-Meier survival analysis showed that the estimated 3-year overall survival (OS) rate of the 37 (64.9%) MRD1+ patients who underwent transplantation was significantly higher than that of the 20 (35.1%) MRD1+ patients who did not undergo transplantation (84.6% vs 40.0%, P =0.0001). Among the 35 MRD1+ MRD2- patients, the 3-year OS rate of the 25 children who underwent transplantation was higher than that of the 10 children who did not undergo transplantation (87.2% vs 70.0%, P =0.3229). The 3-year OS rate of the 19 MRD1+ MRD2+ patients was lower than that of the 35 MRD1+ MRD2- patients (57.4% vs 81.8%, P =0.059). In the 19 MRD2+ patients, the 3-year OS rate of the 12 children who underwent transplantation was significantly higher than that of the 7 children who did not undergo transplantation (80.8% vs 14.3%, P =0.0007). There was no significant difference in 3-year OS between the 12 MRD1+ MRD2+ patients and 25 MRD1+ MRD2- patients, both treated with transplantation (80.8% vs 87.2%, P =0.8868). In those not treated with transplantation, the 7 MRD1+ MRD2+ patients had a significantly lower 3-year OS compared with the 10 MRD1+ MRD2- patients (14.3% vs 70.7%, P =0.0114). Further multivariate analysis indicated that MRD2 positivity and transplantation were both independent prognostic factors (P =0.031, 0.000), while MRD1 positivity was not significantly associated with the overall prognosis of 97 patients (P =0.902). MRD positivity following the second cycle of induction chemotherapy is an independent risk factor for unfavorable outcomes in children with AML. MRD2 positivity indicates a poorer prognosis and can help to identify the candidates requiring transplantation. MRD2 positivity is not a contraindication for transplantation in pediatric patients, and early transplantation significantly improves the prognosis of high-risk patients.

A 5-Year Follow-up Clinical Study of the B-cell Maturation Antigen Chimeric Antigen Receptor T-cell Therapy HDS269B in Patients with Relapsed or Refractory Multiple Myeloma.

This study aimed to report the 5-year clinical outcomes of anti-B-cell maturation antigen chimeric antigen receptor (CAR) T-cell (HDS269B) therapy in patients with relapsed/refractory multiple myeloma (RRMM), including those with poor performance status [Eastern Cooperative Oncology Group (ECOG) scores 3 to 4], and to identify factors influencing long-term outcomes. Forty-nine patients with RRMM enrolled from 2016 to 2020 received HDS269B (9 × 106 cells/kg) after receiving a conditioning chemotherapy consisting of cyclophosphamide and fludarabine. The overall response, long-term outcomes, and safety were assessed, as were their associations with clinical and disease characteristics. With a median follow-up of 59.0 months, the overall response rate was 77.55%. The median progression-free survival (PFS) and overall survival (OS) were 9.5 months [95% confidence interval (CI), 5.01-13.99] and 20.0 months (95% CI, 11.26-28.74), respectively. The 5-year PFS and OS rates were 21.3% (95% CI, 12.3%-36.7%) and 34.1% (95% CI, 22.7%-51.3%), respectively. Patients with ECOG 0 to 2 had marked longer survival, with a median PFS of 11.0 months and a median OS of 41.8 months. Early minimal residual disease negativity, higher and persistent CAR T-cell expansion, and the absence of extramedullary disease were associated with better survival outcomes. No new CAR T-cell therapy-associated toxicities were observed. Importantly, ECOG scores 0 to 2, prior therapy lines <4, and CAR T-cell persistence at ≥6 months were independently associated with longer OS. HDS269B is effective and safe, especially for patients with ECOG scores 0 to 2. Early CAR T-cell intervention may improve prognosis in patients with RRMM.

Abstract 2300: AI enabled whole exome&amp; transcriptome liquid biopsy addressing MCED, MRD, and therapy selection on a single platform

Abstract Effective clinical management of cancer patients requires an accurate and early diagnosis, highly sensitive monitoring of minimal residual disease (MRD), and precise therapy selection. There are multiple tests available that attempt to address each of these needs independently with varying degrees of clinical utility. Caris Assure is a proprietary circulating nucleic acid sequencing platform that couples whole exome and transcriptome (WES/WTS) sequencing on white blood cells and plasma with advanced machine learning techniques to satisfy all three testing needs on one platform. This test detects SNVs, INDELs, structural variants, copy number, gene expression, tumor mutational burden (TMB), microsatellite instability (MSI), fragment length, and aneuploidy of both somatic (tumor and clonal hematopoiesis) and germline origin. Caris’ extensive database of over 350,000 tissue WES/WTS from solid malignancies was used to train deep learning neural networks to identify the molecular underpinnings of cancer. These networks were then deployed on WES/WTS data from plasma and buffy coat in pursuit of signals that can inform early detection, MRD and therapy selection. Validation studies were performed to characterize the analytic and clinical performance of Assure on over 3000 patient blood samples. These samples include ~1000 non-cancer patients (controls), ~1700 newly diagnosed patients where blood was collected at surgery (early detection), ~500 early-stage patients during adjuvant therapy at multiple time points (MRD), and ~200 locally advanced/metastatic patients where matched tissue testing was also performed (therapy selection). For early detection, stratification of blood samples from patients with stage I-IV cancer versus those with no reported cancer resulted in an AUC &amp;gt; 0.99 and included over 30 types of solid tumors. Notably, at 99.5% specificity, the sensitivities for stages I-IV (n= 119, 54, 50, 27) were 73%, 80%, 76%, and 89%. In the MRD setting for high-risk patients, the disease-free survival of patients whose cancers were predicted to recur was significantly shorter (39.6 mo) than those predicted not to recur (93.4 mo) (HR: 5.18, 95%CI: 2.94-9.09, p&amp;lt;.00001). This performance was observed across multiple lineages of cancer including but not limited to breast, colon, lung, and bladder. Lastly, for therapy selection, detection of driver mutations where blood was collected within 30 days of matched tissue demonstrated high concordance with a PPA of 93.8% and PPV of 96.8%. CHIP correction proved to be essential as ~35% percent of patients had CHIP mutations, including KRAS, BRAF, ATM, BRCA1/2, findings that could lead to improper therapy selection. Herein, we demonstrate for the first time a single liquid biopsy assay that addresses the entire continuum of care in clinical oncology with optimal diagnostic, prognostic, and predictive utility for patients and physicians. Citation Format: Jim Abraham, Valeriy Domenyuk, Maria Perdigones Borderias, Takayuki Yoshino, Elisabeth I. Heath, Emil Lou, Stephen Liu, John Marshall, Wafik S. El-Deiry, Anthony Shields, Martin Dietrich, Yoshiaki Nakamura, Takao Fujisawa, David D. Halbert, Dominic Sacchetti, Seth Stahl, Adam Stark, Sergey Klimov, Sourabh Antani, Chadi Nabhan, Jeffrey Swensen, George Poste, Matt Oberley, Milan Radovich, George W. Sledge, David Spetzler. AI enabled whole exome&amp; transcriptome liquid biopsy addressing MCED, MRD, and therapy selection on a single platform [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 2300.

Early Peripheral Blood Minimal Residual Disease Status By NGS in Patients with Newly Diagnosed Multiple Myeloma (MM) on a Phase 2 Trial Receiving Elotuzumab, Carfilzomib, Lenalidomide, and Dexamethasone (Elo-KRd)

Background: Assaying for minimal residual disease (MRD) in the peripheral blood (PB) of patients with multiple myeloma (MM) could solve issues of patchy and extramedullary disease leading to false-negative MRD tests based on bone marrow (BM) only assessments. However, PB testing is challenging due to limited circulating myeloma cells and/or paraprotein. Further, early PB assessments for MRD by paraprotein are unreliable due to the extended half-lives of immunoglobulins. In this analysis, we investigated the concordance and prognostic significance of early MRD status after 4 cycles of treatment with Elo-KRd by next generation sequencing (NGS) in both the BM and PB and by International Myeloma Working Group (IMWG) response criteria. Methods: All patients received 12 cycles of Elo-KRd in 28-day cycles without intent for stem cell transplant: Elo per standard dosing; K 56/70 mg/m 2 (highest tolerated) days 1, 8 and 15 (20 mg/m 2 on day 1 of cycle 1) ; R 25 mg days 1-21; and dexamethasone 40 mg days 1, 8, 15, 22. An MRD-adapted design was used to determine the duration of carfilzomib as previously reported (Derman et al. JAMA Oncology 2022). MRD by NGS in BM (sensitivity threshold 10 -6,clonoSEQ, Adaptive Biotechnologies) was performed at multiple timepoints per protocol. PB mononuclear cells were evaluated for MRD using the same assay; any quantifiable signal was considered positive in PB. Conventional response was assessed per IMWG response criteria. Paired IMWG response and MRD status in the PB and BM were assessed for concordance and prognostic significance at the end of cycle 4 (C4). The Kaplan-Meier method was used to assess progression free survival (PFS) based on a landmark assessment at C4. Results: A total of 46 patients initiated treatment with Elo-KRd; patient baseline characteristics were reported previously (Derman et al. JAMA Oncology 2022). With a median follow-up of 39 months, estimated 4-year PFS was 75%. Of the 42 patients in response at C4, 39 (93%) achieved &amp;gt;VGPR, and 13 (31%) reached &amp;gt;CR. When stratified by &amp;gt;CR vs &amp;lt;CR at C4, there was no difference in PFS (HR 1.4, 95% CI 0.3-6.9, p=0.7). BM MRD status at C4 was available for 34 patients: 11 (32%) patients were BM MRD(-)and 23 (68%) were MRD(+). Matched PB MRD samples at C4 were available for 31 patients; 22 (69%) patients were PB MRD(-) using the best available threshold based on sample input (16 at 10 -6, 6 at 10 -5). Of the 9 (31%) patients with PB MRD(+), 6 (67%) had at least one high-risk cytogenetic abnormality (del17p in n=4, +1q in n=2, t(4;14) in n=1). Extramedullary disease relapse was a manifestation of progression in 4 (44%) patients. BM MRD(-) at C4 was associated with superior PFS (HR not estimable, p=0.04; Figure 1A). No patient with MRD(-) BM after C4 had disease progression. PB MRD(+) at C4 was also associated with inferior PFS (HR 21, 95% CI 2.3-184, p=0.002; Figure 1B). In comparing BM and PB MRD status, 8/9 (89%) patients with PB MRD(+) at C4 had BM MRD(+), and 14/22 (61%) patients with BM MRD(+) at C4 had PB MRD(-). 3/9 (33%) patients with PB MRD(+) at C4 were in &amp;gt;CR; 16/22 (73%) patients with PB MRD(-) at C4 were in a PR/VGPR. With progression serving as the reference standard, PB MRD(+) carried a sensitivity of 71%, a specificity of 83%, a positive predictive value of 56%, and a negative predictive value of 91%. There were 19 matched BM MRD(+)/PB MRD(+) samples across all timepoints; Pearson's correlation coefficient of detected cells per million between BM and PB MRD was r=0.93. BM MRD detected aberrant cells at higher concentrations, with a median log difference of 1.38 compared to PB MRD (range 0.07-3). Conclusions: MRD by NGS in the PB was less sensitive compared to the same assessment in the BM by 1-2 logs; however, PB MRD status following 4 cycles of induction therapy was strongly prognostic given its association with PFS. PB MRD status early in treatment may represent a leading indicator of early response and/or a marker of high-risk disease features, and validation of these findings may help to eventually guide intensification of therapy.

Sequential Chemotherapy and Blinatumomab to Improve Minimal Residual Disease in Adult Ph- B-Lineage Acute Lymphoblastic Leukemia. Final Results of the Phase II Gimema LAL2317 Trial

Introduction. The outcome of adult patients with acute lymphoblastic leukemia (ALL) has markedly improved following the introduction of a pediatric inspired chemotherapy backbone coupled with minimal residual disease (MRD) monitoring at well-defined timepoints (TP), translating into a rational patients' stratification for allogeneic transplantation (Tx). Immunotherapy, in particular blinatumomab, represents a further advancement in the management of ALL. We designed a phase II trial (GIMEMA LAL2317) for adult Ph- CD19+ B-lineage ALL (Ph- B-ALL) consisting of a pediatric chemotherapy backbone - with dose adjustment in patients &amp;gt;55 years - to which 2 cycles of blinatumomab were added, the first after early consolidation cycle 3 (high-dose methotrexate and Ara-C) and the second after late consolidation cycle 6. Tx allocation was based on MRD assessment, carried out in most cases by RQ-PCR and by flow cytometry when a sensitive molecular marker was not identified. The primary objective of the trial was to assess the impact of blinatumomab in increasing the rate of early MRD negativity at end of week 14 (TP3). Patients and methods. The protocol was designed for adults up to the age of 65 years with newly diagnosed Ph- B-ALL; 149 patients were enrolled. Median age was 41 years (18-65), with 28 patients (19%) being older than 55. Eighty-one patients were males, and the median white blood count (WBC) was 4.5x10 9/l (1-474); 12 cases harbored the KMT2A rearrangement, 5 the TCF3:: PBX1 transcript and 31 were classified as Ph-like according to the BCR/ABL1-like predictor . The median follow-up is 37.5 months (0.55-62.8) Results. At the end of induction (TP1, after cycles 1 and 2), 131 patients (88%) were in complete remission (CR), with a significant difference according to age: 94%, 92% and 64% in the 18-40, 40.55 and &amp;gt;55 years cohorts, respectively (p&amp;lt;0.001). All patients with KMT2A and TCF3::PBX1 rearrangements achieved a CR, while 5 Ph-like patients did not. At TP2, i.e. after early consolidation, 85 patients (70%) became MRD-negative (MRD neg). TP3, after the 1 st blinatumomab cycle, 102 patients were MRD neg; the rate of MRD negativity increased to 93% (p&amp;lt;0.001). Imposable results were obtained considering only paired MRD samples. Eight patients remained MRD pos, including 4 with a KMT2A rearrangement and 1 with a E2A::PBX1 rearrangement. OS and DFS at 36 months are 71% and 66% on the whole cohort. OS was significantly different (p=0.00013) according to age cohorts: 76%, 74% and 49% for patients aged 18-40, 40-55 and &amp;gt;55 years, respectively. Likewise, DFS was 71%, 62% and 42% for the same age cohorts, without reaching statistical significance. When patients were stratified for TP2 MRD, OS and DFS were significantly better for MRD neg vs MRD pos cases (p=0.0006 and p&amp;lt;0.0001, respectively). At variance, at TP3, with the caveat of the small sample size of MRD pos patients, the differences between MRD neg and MRD pos patients at TP3 were abolished: indeed, OS and DFS were 82% and 68% for MRD neg, 80% and 70% for MRD pos and 88% and 72% for those lacking MRD evaluation (Figure). Finally, 30 relapses have so far occurred, including 10 Ph-like, 1 KMT2A and 3 TCF3::PBX1 rearranged cases. The overall cumulative incidence of relapse (CIR) was 27.5%; of note, within TP3 MRD neg patients CIR was 42.5% in Ph-like cases vs 17.5% in the remaining patients. By univariate analysis, significant factors for OS were age (p&amp;lt;0.001), CR achievement (p&amp;lt;0.001) and TP2 MRD (p=0.002); TP2 MRD retained significance in multivariate analysis (p=0.001). Univariate analysis for DFS showed as significant the Ph-like signature (p=0.026) and TP2 MRD (p&amp;lt;0.001); both retained statistical significance in multivariate analysis (p=0.021 and &amp;lt;0.001, respectively). Toxicity details will be provided. Conclusions. This phase II trial shows the benefit of adding blinatumomab for the management of Ph- B-ALL, with the primary objective being achieved with 93% of patients being MRD neg after the 1 st cycle of blinatumomab. With a median follow-up of 37.5 months, OS and DFS are 71% and 66%, respectively, better than in historical results, particularly in patients up to the age of 55. Importantly, at TP3 the MRD status no longer impacted, highlighting the therapeutic role of blinatumomab, as observed in Ph+ ALL. Finally, the Ph-like signature retains its negative prognostic impact, suggesting that a combination strategy, similar to that in place for Ph+ ALL, is required.

Treatment of Molecular Relapses in Pediatric AML Saves Toxicities Prior to Hematopoietic Stem Cell Transplantation (HSCT) - Results of AMoRe2017 Trial

Introduction The long-term survival for children with AML has increased to 70 % - but relapsed AML patients still have a poor prognosis (about 30 %). Recent data suggest that in AML residual leukemic cells below the 5 % limit required for a morphologic CR can adversely affect outcome and that increasing levels of Minimal Residual Disease (MRD) are almost always followed by clinical relapse. Early MRD detection provides an opportunity to implement pre-emptive therapies as a bridge-to-transplant approach, to potentially prevent hematological relapse and increase the probability of successful HSCT. A promising approach is the use of Azacitidine (Aza) for treatment of molecular relapse which we evaluated within the clinical trial “AMoRe2017”. Aza has been shown to reverse epigenetic changes in malignant cells, restoring the normal function of genes critical for differentiation and cell cycle control. The trials' primary objective was the evaluation of the effect of Aza treatment in AML subjects at molecular relapse after CR1 regarding molecular response prior to further treatment (reinduction/HSCT). Patients and Methods AMoRe2017 enrolled children with AML (N=20), &amp;gt;3 months &amp;lt; 21 yrs., of which n=1 dropped out due to laboratory measurement error. The median age was 10.9 yrs. (range 1.7-18.9 yrs.). N=10 (53 %) had a CBFB-AML, n=5 (27 %) KMT2A-rearrangement, n=1 (5 %) NUP98::NSD1, n=1 (5 %) FLT3-ITD, n=1(5 %) PICALM::MLLT10 and n=1 (5 %) NPM1. N=8 (42 %) were classified to subgroup M2, n=4 (21 %) to M5, n=3 (16 %) into M1 and n=4 (21 %) to M4/M4 Eo. At baseline, the white blood cell count averaged 3.8x10 9/l (range 0.1-6.6x10 9/l), without leukemic blasts in PB or BM. Each patient had at least one quantifiable genetic marker (rt-PCR), achieved CR with molecular remission, following initial therapy, and subsequently had a molecular relapse (defined as an increase of the MRD level by at least 1 log, less than 5 % BM myeloblasts and absence of proven extramedullary disease). Patients were treated for up to 6 cycles with 75 mg/m 2 i.v. Aza on days 1 to 7 in a 28-day cycle. Molecular response was categorized as molecular stabilization (&amp;lt; 1 log decrease or increase from baseline), molecular progression (≥ 1 log increase from baseline without hematological relapse), molecular improvement (≥ 1 log decrease from baseline), and hematological relapse (at least 5 % blasts in PB and/or BM and/or proven histological extramedullary relapse). Results During Aza treatment, 10 patients (53 %) had an open relapse, which occurred in n=9 after 1 st or 2 nd cycle. These patients were monitored for KMT2A::SEPTIN6 (n=1), KMT2A::MLLT3 (n=2), PICALM::MLLT10 (n=1), FLT3-ITD (n=1), NUP98::NSD1 (n=1), CBFB::MYH11 (n=1) and RUNX1::RUNX1T1 (n=3). 9 patients (47 %; RUNX1::RUNX1T1 n=5, CBFB::MYH11 n=1, NPM1 n=1, KMT2A::ELL n=2) showed a molecular response to Aza and proceeded to HSCT without receiving intensive re-induction treatment. 16 out of the 19 patients are alive (overall survival 84 %), 2 died from HSCT-associated side effects (VOD, infection), and 1 from disease progression. Considering genetics, 7 out of 11 patients with favorable genetics (core-binding leukemia n=10 or NPM1 n=1) responded to the Aza therapy ( RUNX1::RUNX1T1 n=5, CBFB::MYH11 n=1, NPM1 n=1). By contrast, in cases with KMT2A-rearrangements, NUP98::NSD1 or FLT3-ITD, 2 out of 8 patients showed improvement or stabilization. In total 152 adverse events (AEs) associated to Aza were reported, the majority classified as grade 1 or 2 (n= 114; 75 %). Mainly affected was the hematopoietic system (40 %), the gastrointestinal tract (15 %), kidney and liver (14 %). Cardiotoxicity was not reported. Discussion The use of Aza as pre-emptive “bridge-to-transplant” approach treating the molecular relapse showed efficacy in patients with RUNX1::RUNX1T1, CBFB::MYH11, NPM1, and KMT2A::ELL, who could be transplanted directly. This pilot provided proof of principle that molecular relapses could be treated, and MRD levels be reversed, at least in subgroups. In addition, avoiding intensive re-induction therapy prior to HSCT is feasible. Conversely, the relatively slow-acting mechanism of epigenetic therapy seems to be ineffective in highly proliferative subgroups of AML with KMT2A-rearrangements or FLT3-ITD. Further studies are mandatory to define treatment options for molecular relapses of non-favorable pediatric AML and to confirm potential improvement of outcome post-HSCT.

Clinical Benefit of Autologous Stem Cell Transplantation for Patients with Multiple Myeloma Achieving Undetectable Minimal Residual Disease after Induction Treatment.

Achieving and maintaining undetectable MRD is the current treatment goal for multiple myeloma. Our results emphasized the remarkable clinical benefit of ASCT on MRD-negative duration, PFS, and OS in patients with multiple myeloma regardless of early MRD status. These favorable impacts were more evident in patients with aggressive features. Importantly, dynamic MRD monitoring among ASCT could facilitate personalized stratification of therapeutic approaches.

17th International Conference on Malignant Lymphoma, Palazzo dei Congressi, Lugano, Switzerland, 13 - 17 June, 2023.

Introduction: Minimal disease determination might serve for risk stratification, response evaluation and follow-up disease monitoring in childhood Non-Hodgkin lymphomas. Besides helping to judge minimal residual disease (MRD) during therapy, detection of minimal disseminated disease (MDD) at diagnosis may be of prognostic value itself. However, different subtypes, high cure rates, low patient numbers, limited initial tumour material and early progression pose challenges. Methods: Pubmed literature search on MDD and MRD in pediatric lymphomas. Results: Current clinical applications of minimal disease determination differ between the subtypes. For lymphoblastic lymphomas, both flow-cytometry detecting aberrant immunophenotypes and PCR-based assays for TCR- or Ig-rearrangements have been used for minimal disease measurement. A prognostic value of MDD could not be clearly established yet. MRD has not been analysed in larger patient cohorts so far. In Burkitt-lymphoma and -leukemia, MYC-Ig-fusion sequences or Ig-rearrangements enable minimal disease detection. While conflicting data on the role of MDD as risk factor for Burkitt lymphoma have been published, the prognostic value of early MRD in Burkitt leukaemia treated by risk-adapted chemotherapy has been described by two study groups. However, its role in the rituximab-era needs to be confirmed. In ALK-positive anaplastic large cell lymphoma (ALCL), MDD and MRD determined by qualitative or quantitative PCR for ALK-fusion transcripts are validated independent prognostic parameters. They are standard of care parameters assessed in routine clinically practice and used for patient stratification in clinical studies. Early MRD might even serve as endpoint for clinical trials and for guiding individual therapy. Conclusions and future outlook: Validation of MDD and MRD as prognostic parameters is required for all subtypes but ALCL. Next-generation sequencing based methods and the use of circulating cell-free tumour DNA as medium may provide new options and applications for minimal disease evaluation in childhood lymphomas. Keywords: diagnostic and prognostic biomarkers, minimal residual disease, non-Hodgkin (pediatric, adolescent, and young adult) No conflicts of interests pertinent to the abstract.

Baseline and early post-infusion biomarkers associated with optimal response to idecabtagene vicleucel (ide-cel) in the KarMMa-3 study of triple-class–exposed (TCE) relapsed and refractory multiple myeloma (RRMM).

8031 Background: Ide-cel, a B-cell maturation antigen (BCMA) chimeric antigen receptor T cell therapy, significantly improved median progression-free survival (mPFS) and overall response rate (ORR) vs standard regimens (SRs) in patients (pts) with TCE RRMM in the KarMMa-3 study (NCT03651128; Rodríguez-Otero et al. NEJM 2023). Previous analyses in KarMMa (Munshi et al. NEJM 2021) of pts with later-line (4L+) TCE RRMM identified low baseline (BL) levels and complete clearance of soluble BCMA (sBCMA, a measure of tumor burden) and early minimal residual disease (MRD) negativity as correlates of durable response to ide-cel. The current analysis explored the association between biomarkers and efficacy or severity of inflammatory adverse events of ide-cel in KarMMa-3. Methods: sBCMA levels were measured in blood samples collected from pts in KarMMa-3 at BL and regular intervals from treatment (tx) initiation until confirmed progression. MRD status was assessed in bone marrow aspirate (clonoSeq; 10-5 sensitivity) at 6 and 12 mo post infusion and reported in all pts, regardless of response. Biomarker analyses were based on pts who received ide-cel or ≥1 dose of SR. Post hoc analyses assessed correlations between biomarkers and efficacy endpoints or cytokine release syndrome (CRS) and investigator-identified neurotoxicity (iiNT); associations of interest were identified using a ranked sum test and nominal P value &lt; 0.05. Results: Lower BL sBCMA levels were associated with higher ORR ( &lt; partial response [PR] vs ≥PR) in both tx arms (ide-cel, P= 0.0223; SR, P= 0.0395), indicating this may be agnostic of the BCMA-directed modality. Lower BL sBCMA was also associated with higher complete response (CR) rate ( &lt; CR vs ≥CR) in the ide-cel arm ( P= 0.0038). Additionally, lower BL sBCMA levels in the ide-cel arm were associated with lower grade (gr) of CRS (gr 0–1 vs 2 vs ≥3; P= 0.0022) and iiNT (gr 0–1 vs ≥2; P= 0.0113); however, overlapping ranges may limit predictive utility. Further analyses will be presented. In the ide-cel arm, landmark mPFS was longer in pts with undetectable versus detectable sBCMA at 2 mo post infusion (16.3 vs 5.2 mo; HR, 0.26) or at 6 mo (16.8 vs 9.6 mo; HR, 0.62). Furthermore, landmark mPFS was also longer in pts with MRD negativity versus pts with positive/indeterminate MRD status at 6 mo (17.2 vs 5.8 mo; HR, 0.288) or at 12 mo (13.8 vs 4.6 mo; HR, 0.121). Conclusions: BL sBCMA levels correlated with response and CRS and iiNT grade in the ide-cel arm of KarMMa-3, potentially reinforcing the importance of management of BL tumor burden for optimal response to ide-cel. Early clearance of sBCMA at 2 mo, sustained clearance of sBCMA at 6 mo, and MRD negativity at 6 or 12 mo, regardless of clinical response, may be useful biomarkers for identifying pts likely to achieve a complete and durable response to ide-cel. Clinical trial information: NCT03651128 .

Prognostic value of early bone marrow MRD status in CAR-T therapy for myeloma

Bone marrow (BM) assessment of minimal residual disease (MRD) is prognostic for survival in multiple myeloma (MM). BM is still hypocellular at month 1 post CAR-T, thus the value of MRD negative (MRDneg) status at this timepoint is unclear. We examined the impact of month 1 BM MRD status in MM patients who received CART at Mayo Clinic between 8/2016 and 6/2021. Among 60 patients, 78% were BM-MRDneg at month 1; and 85% (40/47) of these patients also had decreased to less than normal level of both involved and uninvolved free light chain (FLC < NL). Patients who achieved CR/sCR had higher rates of month 1 BM-MRDneg and FLC < NL. The rate of sustained BM-MRDneg was 40% (19/47). Rate of conversion from MRDpos to MRDneg was 5%(1/20). At month 1, 38%(18/47) of the BM-MRDneg were hypocellular. Recovery to normal cellularity was observed in 50%(7/14) with a median time to normalization at 12 months (range: 3–Not reached). Compared to Month 1 BM-MRDpos patients, patients who were BM-MRDneg had longer PFS irrespective of BM cellularity [PFS: 2.9 months (95% CI, 1.2-NR) vs. 17.5 months (95% CI, 10.4-NR), p < 0.0001]. Month 1 BM-MRDneg and FLC below normal were associated with prolonged survival. Our data support the continued evaluation of BM early post-CART infusion as a prognostic tool.

Abstract 5599: An introduction of a highly sensitive circulating tumor DNA monitoring system for minimal residual disease detection using a library of 1000 digital PCR probes

Abstract Background: Many patients undergo a next generation sequencing (NGS)-based cancer genome profiling (CGP) test, but it often does not aid in choosing an optimal therapeutic regimen. Therefore, the genomic information should be used for minimal residual disease (MRD) detection, which directly leads to improved post-treatment cancer patient management. Circulating tumor DNA (ctDNA) is a small fraction of DNA present in blood that carries somatic mutations in cancer patients. Our previous studies demonstrated the clinical validity of ctDNA as a tumor marker for MRD detection. However, the variant allele frequency (VAF; reflecting the fraction of somatic mutations) of ctDNA is less than 1%, at which stable detection is difficult for NGS. Instead of NGS, we have established a highly sensitive ctDNA monitoring system for MRD detection using an originally developed library of &amp;gt;1000 digital PCR (dPCR) probes. Patients and Methods: Using a Clinical Institutional Review Board approval from the Iwate Medical University Hospital, we initiated a dPCR assay system, called off-the-shelf (OTS)-Assay, in April 2022 under a partnership with Quantdetect, Inc (Tokyo, Japan). The OTS-Assay has three main components: OTS-Scan, OTS-Select, and OTS-Monitor. The OTS-Scan can provide an original CGP if a patient comes with no CGP results. The OTS-Select chooses matched somatic mutations from our dPCR probe library. The OTS-Monitor quantifies VAFs of ctDNA periodically in the patient plasma with a sensitivity of 0.05% VAF. There is no strict patient eligibility criteria other than the requirement of previous therapy for treatment of an advanced cancer. Results: Between April and November 2022, 26 patients visited Iwate Medical University Hospital for the OTS-Assay. Twenty-five patients were referred from other Departments of Iwate Medical University Hospital. The primary cancer types include esophagus (n=21), colorectal (n=2), pancreas (n=2), and breast (n=1). Twenty patients had CGP results at their first visit. OTS-Select were used for 13 patients and picked an average of 11.4 mutations per patient. Among those, each of eight patients were immediately able to start ctDNA monitoring with one of the 1000 dPCR probes. As of November 2022, there are four patients who received OTS-Monitor more than one time. Any unexpected VAF increase of ctDNA has not been noted, although a substantial decrease of ctDNA VAF was found in one patient who received one cycle of chemotherapy. Conclusion: The OTS-Assay is a practical introduction of our previous clinical research products based on a core technology, which uses an originally developed library of &amp;gt;1000 dPCR probes. The potential of early and accurate MRD detection will improve post-treatment cancer patient management. Citation Format: Satoshi S. Nishizuka, Hayato Hiraki, Masakazu Abe, Akiko Yashima-Abo, Takeshi Iwaya. An introduction of a highly sensitive circulating tumor DNA monitoring system for minimal residual disease detection using a library of 1000 digital PCR probes. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5599.

Treatment outcomes for acute T-lymphoblastic leukemias/lymphomas: data from the ALL-2016 multicenter prospective randomized trial

Background . The effectiveness of therapy for acute T-lymphoblastic leukemia (T-ALL) and T-lymphoblastic lymphoma (T-LBL) has significantly improved over the past decades, including through the implementation of hematopoietic stem cell transplantation (HSCT). The Russian multicenter ALL-2009 study (ClinicalTrials.gov NCT01193933) showed that performing autologous HSCT (auto-HSCT) in patients with T-ALL/LBL improves long-term results. However, the study was non-randomized and the need for auto-HSCT in clinical practice requires careful study. Aim . To assess the significance of auto-HSCT in patients with T-ALL/LBL in the framework of ALL-2016 multicenter, prospective, randomized study (ClinicalTrials.gov NCT03462095). Materials and methods . The study included 109 adult patients with T-ALL/LBL (m:f 82:27). Median age was 31 (18– 52) years. T-ALL was diagnosed in 88 (81 %) patients, T-LBL in 21 (19 %) patients. All patients are treated according to the ALL-2016 protocol. Using the web platform, upon completion of induction therapy (+70 days), all T-ALL/LBL patients who achieved clinical and hematological remission were randomized to the auto-HSCT arm or chemotherapy alone (CT). Centralized monitoring of minimal residual disease (MRD) in bone marrow samples was performed by multicolor flow cytometry at the control points according to the ALL-2016 protocol. Statistical analysis was performed using SAS 9.4. Results . 87 patients with T-ALL/LBL were randomized: 44 to the auto-HSCT arm and 43 to the CT arm. Further analysis included 25 patients who underwent auto-HSCT and 36 patients receiving only CT. Three-year relapse-free survival in T-ALL is estimated at 62 % (auto-HSCT) vs. 81 % (CT) (p = 0.3422), and in T-LBL – 67 % (auto-HSCT) vs. 79 % (CT) (p = 0.59). MRD persistence on the +70 th day of therapy according to the ALL-2016 protocol was determined in 40 % of patients (autoHSCT) and in 67 % (CT) (p = 0.057). In a multivariate analysis, it was determined that T-ALL from early T-cell precursor (ETP-variant) and MRD persistence after the end of II phase induction are the main risk factors for relapse in the treatment according to the ALL-2016 protocol. Conclusion . Performing auto-HSCT both in patients with T-ALL and T-LBL, and with MRD persistence on day +70 according to the ALL-2016 protocol did not improve long-term results. The development of new programs for the treatment of patients with MRD persistence, as well as the ETP variant of T-ALL, is of current interest.

Comparison of the treatment results in adult patients with acute Ph-negative lymphoblastic leukemia on protocols of the Russian multicenter studies ALL-2009 and ALL-2016

Introduction. Over the past 5 years, signifi cant progress has been achieved in the treatment of patients with Ph-negative acute lymphoblastic leukemia (ALL). Treatment results were compared between two protocols of the Russian multicenter studies «ALL-2009» and «ALL-2016», in which multicomponent high-dose consolidation was not used. The principle of continuity of treatment was observed with modifi cation of doses of cytostatic drugs depending on the depth of cytopenia.Aim – to compare the 5-year results of two studies and to determine the factors of unfavorable prognosis in the treatment of patients with ALL.Materials and methods. The studies were performed from April 2009 to April 2016 (ALL-2009) and from April 2016 to September 2021 (ALL-2016), and 596 patients were included: 330 in ALL-2009 and 266 in ALL-2016. The analysis was performed in March 2022. The median age of patients in ALL-2009 was 28 years (15–55), in ALL-2016 – 32.5 years (18–55). Cytogenetic studies were performed in 242 patients in ALL-2009 (73.3 %) and 236 patients in ALL-2016 (88.7 %). Patients in the ALL-2016 protocol underwent a centralized assessment of minimal residual disease (MRD) by fl ow cytometry on protocol +70 day (after completion of two induction phases), +133 and +190 days. Transplantation of allogeneic stem hematopoietic cells was performed in 7 % of patients in ALL-2009 and in 9 % in ALL-2016.Results. Overall, relapse-free survival (OS, RFS) and the probability of relapse for a period of 3 years from the moment of inclusion of patients in a particular study were 59 %, 63 % and 23 % for ALL-2009, and for ALL-2016 – 64 %, 59 % and 22 %, respectively. For patients with B-cell precursor ALL, two cytogenetic risk groups were formed, in which long-term survival rates differed signifi cantly: the standard group (hyperploid set of chromosomes and normal karyotype) – OS 63 %, RFS 70 %, and high cytogenetic risk (any abnormal karyotype, except for hyperploidy) – OS 49 %, RFS 52 % (р = 0.001, р = 0.0014). In T-ALL, cytogenetic markers had no prognostic value, but the immunophenotype of early T-cell precursor turned out to be an important predictor of poor prognosis (the probability of relapse was 52 % compared with 15 % for all other immunophenotypic variants). According to the results of centralized monitoring of MRD, it was determined that for B-cell precursor ALL, the signifi cant negative factors are the high cytogenetic risk group and positive MRD status at +70 day, and for T-cells, the early immunophenotype and positive MRD status at +133 day.

New developments in ALL in AYA

The outcome for adolescents and young adults (AYA) with acute lymphoblastic leukemia (ALL) has improved, mostly based on the use of pediatric-inspired intensive protocols. Due to increasing disease resistance and treatment-related toxicity with age, further improvements are now expected from the expanding knowledge of ALL biology, more accurate risk stratification, and the early introduction of targeted small molecules and immunotherapy. In the last decade, the rate of AYA with B-cell precursor ALL with undetermined genetic drivers ("B-other") has shrunk from 40% to fewer than 10%. The high-risk subgroup of Philadelphia-like ALL is the most frequent entity diagnosed in this age range, offering a multitude of potentially actionable targets. The timely and accurate identification of these targets remains challenging, however. Early minimal residual disease (MRD) monitoring has become a standard of care for the risk stratification and identification of patients likely to benefit from an allogeneic hematopoietic stem cell transplantation. Recently approved immunotherapies are moving frontline to eradicate MRD, to improve the outcome of high-risk patients, and, eventually, to reduce treatment burden. Comprehensive care programs dedicated to AYA with cancer aim at improving inclusion in specific clinical trials and at giving access to appropriate psychosocial support, fertility preservation, and survivorship programs.

MRD Status By Clonoseq ® Is a Poor Predictor of Long-Term Outcomes after Bispecific LV20.19 CAR T-Cell Therapy for Relapsed, Refractory B-Cell NHL

INTRODUCTION: The clonoSEQ® Assay (Adaptive Biotechnologies Corporation, Seattle, USA) uses next-generation sequencing (NGS) based testing to identify disease-specific immunoglobulin sequences and detect evidence of minimal residual disease (MRD). MRD assessments have been shown to predict progression-free survival and overall survival in non-Hodgkin's lymphoma (NHL) patients. We report MRD results via the commercially available clonoSEQ® assay and its association with durability of response in patients treated with bispecific LV20.19 CAR in our phase 1/2 trial (NCT04186520). METHODS: We conducted a phase 1/2 single-center prospective trial (NCT04186520) to evaluate the efficacy and safety of LV20.19 CAR T-cells in patients with NHL at 2.5x106 cells/kg dose. LV20.19 CAR T-cells were manufactured onsite at varying lengths of manufacturing (8 vs 12 days) in the CliniMACS Prodigy device with IL7+15 for cell expansion, with the goal of fresh infusion. The commercial clonoSEQ® assay (by Adaptive Biotechnologies) was used to identify and track tumor clonotypes in responding patients at first assessment performed between Day 28-60. We evaluated associations between MRD status and long-term response post LV20.19 CAR-T cell therapy. Descriptive statistics were utilized for baseline characteristics. Survival analyses were calculated utilizing the Kaplan-Meier method and differences between groups were evaluated via the log-rank test. RESULTS: Among the 32 patients enrolled in the trial, there were 26 responders on Day 28. Of these responders, 23 patients had clonoSEQ® B-cell MRD assay done between Day 28-60 post CAR infusion (Table 1). MRD was performed in 11 patients with Diffuse Large B-cell Lymphoma (DLBCL), 3 patients with Follicular lymphoma (FL), and 9 patients with Mantle Cell Lymphoma (MCL). The median age was 64 years (45-74) and the median lines of prior therapy were 4 (2-11). Of the 23 patients with early MRD status available, the day 28 objective response rate (ORR) was 100% (complete response=57%, n=13 and partial response=43%, n=10). Eighteen patients (78%) were MRD negative at first assessment between days 28-60 and 5 (22%) were MRD positive. Of the 5 patients who were MRD positive, 3 became MRD negative at day 90, 1 patient was non-evaluable due to a non-relapse mortality event, and the remaining patient remains positive but with decreasing MRD status at Day 90. None of the patients with MRD positivity at day 28 have relapsed to date. Among patients who achieved early MRD negativity (n=18), 7 (39%) have relapsed, and all were patients with either DLBCL or FL. No MRD-negative MCL patient has relapsed to date. The duration of response in MRD-negative patients was significantly improved in MCL patients compared to DLBCL/FL patients (Figure 1), p=0.02. Among the 7 MRD negative patients who relapsed, only 1 patient was detected to have disease relapse by MRD positivity, 2 were detected simultaneously on MRD testing and imaging, while 3 were detected by physical exam or imaging findings and did not have MRD testing. Interestingly, 1 patient had a central nervous system relapse while being MRD negative. CONCLUSION: Relapse after CAR T-cell therapy remains a significant clinical challenge. New predictors are indicated to determine which responding patients after CAR-T cell therapy are more likely to relapse. Utilizing the commercially available Adaptive clonoSEQ® assay, early MRD assessment was not predictive of long-term clinical outcomes in DLBCL and FL. MRD positive patients maintained durable remission and converted to MRD negativity, while early MRD negative patients continued to relapse. In contrast, MRD negativity post-CAR-T therapy did appear to predict durable clinical remission in MCL patients. Newer assays, including cell-free technologies, may be more informative for non-MCL histologies. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal