Optimizing Molecular Minimal Residual Disease Analysis in Adult Acute Lymphoblastic Leukemia

Minimal/measurable residual disease (MRD) evaluation has resulted in a fundamental instrument to guide patient management in acute lymphoblastic leukemia (ALL). From a methodological standpoint, MRD is defined as any approach aimed at detecting and possibly quantifying residual neoplastic cells beyond the sensitivity level of cytomorphology. The molecular methods to study MRD in ALL are polymerase chain reaction (PCR) amplification-based approaches and are the most standardized techniques. However, there are some limitations, and emerging technologies, such as digital droplet PCR (ddPCR) and next-generation sequencing (NGS), seem to have advantages that could improve MRD analysis in ALL patients. Furthermore, other blood components, namely cell-free DNA (cfDNA), appear promising and are also being investigated for their potential role in monitoring tumor burden and response to treatment in hematologic malignancies. Based on the review of the literature and on our own data, we hereby discuss how emerging molecular technologies are helping to refine the molecular monitoring of MRD in ALL and may help to overcome some of the limitations of standard approaches, providing a benefit for the care of patients

A case of lineage switch from B-cell acute lymphoblastic leukaemia to acute myeloid leukaemia. Role of subclonal/clonal gene mutations

We report the case of a patient with acute lymphoblastic leukaemia (ALL) who displayed a myeloid phenotype at relapse; the molecular IGH marker was conserved in the different phases of the disease. Next‐generation sequencing (NGS) analyses were performed to further characterize this peculiar case. A 40‐year‐old Caucasian female was admitted to our centre in November 2008 with axillary lymphadenopathy. Peripheral blood cell count showed anaemia, thrombocytopenia and a mild leucocytosis; peripheral blood smear morphology revealed the presence of myeloperoxidase‐negative blasts. Bone marrow (BM) aspirate showed 96% blast infiltration and the immunophenotype was diagnostic of a pro‐B ALL (Table ). No fusion genes were detected, while a 46 XX, t(2;16) (p11;p11) karyotype was found in 10/20 metaphases. The cerebrospinal fluid was negative for leukaemic infiltration

Droplet Digital PCR Improves IG-/TR-based MRD Risk Definition in Childhood B-cell Precursor Acute Lymphoblastic Leukemia

: Minimal residual disease (MRD) is the most powerful prognostic factor in pediatric acute lymphoblastic leukemia (ALL). Real-time quantitative polymerase chain reaction (RQ-PCR) represents the gold standard for molecular MRD assessment and risk-based stratification of front-line treatment. In the protocols of the Italian Association of Pediatric Hematology and Oncology (AIEOP) and the Berlin-Frankfurth-Munschen (BFM) group AIEOP-BFM ALL2009 and ALL2017, B-lineage ALL patients with high RQ-PCR-MRD at day+33 and positive at day+78 are defined slow early responders (SERs). Based on results of the AIEOP-BFM ALL2000 study, these patients are treated as high-risk also when positive MRD signal at day +78 is below the lower limit of quantification of RQ-PCR ("positive not-quantifiable," POS-NQ). To assess whether droplet digital polymerase chain reaction (ddPCR) could improve patients' risk definition, we analyzed MRD in 209 pediatric B-lineage ALL cases classified by RQ-PCR as POS-NQ and/or negative (NEG) at days +33 and/or +78 in the AIEOP-BFM ALL2000 trial. ddPCR MRD analysis was performed on 45 samples collected at day +78 from SER patients, who had RQ-PCR MRD ≥ 5.0 × 10-4 at day+33 and POS-NQ at day+78 and were treated as medium risk (MR). The analysis identified 13 of 45 positive quantifiable cases. Most relapses occurred in this patients' subgroup, while ddPCR NEG or ddPCR-POS-NQ patients had a significantly better outcome (P < 0.001). Overall, in 112 MR cases and 52 standard-risk patients, MRD negativity and POS-NQ were confirmed by the ddPCR analysis except for a minority of cases, for whom no differences in outcome were registered. These data indicate that ddPCR is more accurate than RQ-PCR in the measurement of MRD, particularly in late follow-up time points, and may thus allow improving patients' stratification in ALL protocols

Digital Droplet PCR Is a Reliable Tool to Improve Minimal Residual Disease Stratification in Adult Philadelphia-Negative Acute Lymphoblastic Leukemia

Digital droplet PCR (ddPCR) is an implementation of conventional PCR, with the potential of overcoming some limitations of real-time quantitative PCR (RQ-PCR). To evaluate if ddPCR may improve the quantification of disease levels and refine patients' risk stratification, 116 samples at four time points from 44 (35 B-lineage and 9 T-lineage) adult Philadelphia-negative acute lymphoblastic leukemia patients enrolled in the GIMEMA LAL1913 protocol were analyzed by RQ-PCR and ddPCR. A concordance rate between RQ-PCR and ddPCR of 79% (P < 0.0001) was observed; discordances were identified in 21% of samples, with the majority being RQ-PCR-negative (NEG) or positive not quantifiable (PNQ). ddPCR significantly reduced the proportion of PNQ samples-2.6% versus 14% (P = 0.003)-and allowed disease quantifiability in 6.6% of RQ-PCR-NEG, increasing minimal residual disease quantification in 14% of samples. Forty-seven samples were also investigated by next-generation sequencing, which confirmed the ddPCR results in samples classified as RQ-PCR-PNQ or NEG. By reclassifying samples on the basis of the ddPCR results, a better event-free survival stratification of patients was observed compared to RQ-PCR; indeed, ddPCR captured more true-quantifiable samples, with five relapses occurring in three patients who resulted RQ-PCR-PNQ/NEG but proved ddPCR positive quantifiable. At variance, no relapses were recorded in patients whose follow-up samples were RQ-PCR-PNQ but reclassified as ddPCR-NEG. A broader application of ddPCR in acute lymphoblastic leukemia clinical trials will help to improve patients' stratification

Local radiotherapy and measurable residual disease-driven immunotherapy in patients with early-stage follicular lymphoma (FIL MIRO): final results of a prospective, multicentre, phase 2 trial

Background: The mainstay of treatment for early-stage follicular lymphoma is local radiotherapy, with a possible role for anti-CD20 monoclonal antibody (mAb). We aimed to evaluate the effect of these treatments using a measurable residual disease (MRD)-driven approach. Methods: This prospective, multicentre, phase 2 trial was conducted at 27 centres of the Fondazione Italiana Linfomi (FIL) in Italy. Eligible participants were adults (≥18 years) with newly diagnosed, histologically confirmed follicular lymphoma (stage I or II; grade I-IIIa). Patients were initially treated with 24 Gy involved-field radiotherapy over 12 days; those who were MRD-positive after radiotherapy or during follow-up received eight intravenous doses (1000 mg per dose; one dose per week) of the anti-CD20 mAb ofatumumab. The primary endpoint was the proportion of patients who were MRD-positive after involved-field radiotherapy and became MRD-negative after ofatumumab treatment. Patients were included in the primary endpoint analysis population if they were positive for BCL2::IGH rearrangement at enrolment in peripheral blood or bone marrow samples. MRD positivity was defined as the persistence of BCL2::IGH rearrangement in peripheral blood or bone marrow, assessed centrally by laboratories of the FIL MRD Network. The trial was registered with EudraCT, 2012-001676-11. Findings: Between May 2, 2015, and June 1, 2018, we enrolled 110 participants, of whom 106 (96%) were eligible and received involved-field radiotherapy. Of these, 105 (99%) were White, one (1%) was Black, 50 (47%) were male, and 56 (53%) were female. Of 105 participants in whom BCL2::IGH status was evaluable, 32 (30%) had a detectable BCL2::IGH rearrangement at baseline. After radiotherapy, 12 (40%) of 30 patients reached MRD-negative status, which was long-lasting (at least 36 or 42 months) in three (25%). In those who were MRD-positive after radiotherapy, ofatumumab induced MRD-negativity in 23 (92%; 95% CI 74-99) of 25 evaluable patients. After a median follow-up of 46·1 months (IQR 42·8-50·8), 14 (61%) of these 23 patients remain in complete response and are MRD-negative. The most common grade 3-4 adverse events were infusion-related reactions, observed in four patients. Interpretation: Local radiotherapy is frequently not associated with the eradication of follicular lymphoma. An MRD-driven, anti-CD20 monoclonal antibody consolidation enables molecular remission to be reached in almost all patients and is associated with a reduced incidence of relapse over time. A clinical advantage of an MRD-driven consolidation is therefore suggested. Funding: AIRC Foundation for Cancer Research in Italy, Novartis International, and GlaxoSmithKline

High rate of durable responses with undetectable minimal residual disease with frontline venetoclax and rituximab in young and fit patients with chronic lymphocytic leukemia and an adverse biologic profile: results of the gimema phase II LLC1518 - 'Veritas' study

: The GIMEMA phase II LLC1518 VERITAS trial investigated the efficacy and safety of frontline, fixed-duration venetoclax and rituximab (VenR) combination in young (≤65 years) and fit patients with chronic lymphocytic leukemia (CLL) and unmutated IGHV and/or TP53 disruption. Treatment consisted of the Ven ramp-up, six-monthly courses of the VenR combination, followed by six monthly courses of Ven single agent. A centralized assessment of measurable minimal residual disease (MRD) was performed on the peripheral blood (PB) and bone marrow (BM) by ASO-PCR at the end of treatment (EOT) and during the follow-up. The primary endpoint was the complete remission (CR) rate at the EOT. Seventy-five patients were enrolled; the median age was 54 years (range 38-65), 96% had unmutated IGHV, 9 (12%) had TP53 disruption, and 4% were IGHV mutated with TP53 disruption. The overall response rate (ORR) at the EOT was 94.7%, with a CR rate of 76%. An undetectable (u) MRD was recorded in 69.3% of patients in the PB and 58.7% in the BM. The 12-month MRD-free survival in the 52 patients with uMRD in the PB at the EOT was 73.1%. After a median follow-up of 20.8 months, no disease progressions were observed. Three patients have died, two due to Covid-19 and 1 to tumor lysis syndrome. The first report of the VERITAS study shows that frontline VenR was associated with a high rate of CRs and durable responses with uMRD in young patients with CLL and unfavorable genetic characteristics