Development and usability of a virtual reality umbilical venous catheter placement simulator.

PURPOSE: Exposure to procedures varies in the neonatal intensive care unit (NICU). A method to teach procedures should be available without patient availability, expert oversight, or simulation laboratories. To fill this need, we developed a virtual reality (VR) simulation for umbilical vein catheter (UVC) placement and sought to establish its face and content validity and usability. METHODS: Engineers, software developers, graphic designers, and neonatologists developed a VR UVC placement simulator following a participatory design approach. The software was deployed on the Meta Quest 2 head-mounted display (HMD). Neonatal nurse practitioners (NNPs) from a level 4 NICU used the simulator and completed an 11-item questionnaire to establish face and content validity. Participants also completed the validated simulation task load index and system usability scale to assess the usability of the simulator. Group 1 tested the VR simulation, which was optimized based on feedback, prior to Group 2's participation. RESULTS: A total of 14 NNPs with 2-37 years of experience participated in testing. Participants scored the content and face validity of the simulator highly, with most giving scores ≥ 4/5. Usability was established with relatively high average system usability scores for both groups (Group 1: 67.14 ± 7.8, Group 2: 71 ± 14.1) and low SIM-TLX scores indicating manageable load while using the simulator. CONCLUSION: After optimization, Group 2 found the UVC simulator to be realistic and effective. Both groups felt the simulator was easy to use and did not cause physical or cognitive strain. All participants felt the UVC simulator provided a safe environment to make mistakes, and the majority would recommend this experience to trainees.

A randomised phase 2 study of intermittent versus continuous dosing of dabrafenib plus trametinib in patients with BRAFV600 mutant advanced melanoma (INTERIM).

BACKGROUND: BRAF+MEK inhibitors extend life expectancy of patients with BRAFV600 mutant advanced melanoma. Acquired resistance limits duration of benefit, but preclinical and case studies suggest intermittent dosing could overcome this limitation. INTERIM was a phase 2 trial evaluating an intermittent dosing regimen. METHODS: Patients with BRAFV600 mutant advanced melanoma due to start dabrafenib+trametinib were randomised to receive either continuous (CONT), or intermittent (INT; dabrafenib d1-21, trametinib d1-14 every 28 days) dosing. A composite primary endpoint included progression-free survival (PFS) and quality of life (QoL). Secondary endpoints included response rate (ORR), overall survival (OS) and adverse events (AEs). Mutant BRAFV600E ctDNA was measured by droplet digital PCR (ddPCR), using mutant allele frequency of > 1 % as the detection threshold. RESULTS: 79 patients (39 INT, 40 CONT) were recruited; median age 67 years, 65 % AJCC (7th ed) stage IV M1c, 29 % had brain metastases. With 19 months median follow-up, INT was inferior in all efficacy measures: median PFS 8.5 vs 10.7mo (HR 1.39, 95 %CI 0.79-2.45, p = 0.255); median OS 18.1mo vs not reached (HR 1.69, 95 %CI 0.87-3.28, p = 0.121), ORR 57 % vs 77 %. INT patients experienced fewer treatment-related AEs (76 % vs 88 %), but more grade > 3 AEs (53 % vs 42 %). QoL favoured CONT. Detection of BRAFV600E ctDNA prior to treatment correlated with worse OS (HR 2.55, 95 %CI 1.25-5.21, p = 0.01) in both arms. A change to undetected during treatment did not significantly predict better OS. CONCLUSION: INTERIM findings are consistent with other recent clinical trials reporting that intermittent dosing does not improve efficacy of BRAF+MEK inhibitors.

Dabrafenib plus trametinib versus anti-PD-1 monotherapy as adjuvant therapy in BRAF V600-mutant stage III melanoma after definitive surgery: a multicenter, retrospective cohort study.

Background: Both dabrafenib/trametinib (D/T) and anti-PD-1 monotherapy (PD-1) are approved adjuvant therapies for patients with stage III BRAF V600-mutant melanoma. However, there is still a lack of head-to-head comparative data. We aimed to describe efficacy and toxicity outcomes for these two standard therapies across melanoma centers. Methods: This multicenter, retrospective cohort study was conducted in 15 melanoma centers in Australia, China, Germany, Italy, Japan, UK, and US. We included adult patients with resected stage III BRAF V600-mutant melanoma who received either adjuvant D/T or PD-1 between Jul 2015 and Oct 2022. The primary endpoint was relapse-free survival (RFS). Secondary endpoints included overall survival (OS), recurrence pattern and toxicity. Findings: We included 598 patients with stage III BRAF V600-mutant melanoma who received either adjuvant D/T (n = 393 [66%]) or PD-1 (n = 205 [34%]) post definitive surgery between Jul 2015 and Oct 2022. At a median follow-up of 33 months (IQR 21-43), the median RFS was 51.0 months (95% CI 41.0-not reached [NR]) in the D/T group, significantly longer than PD-1 (44.8 months [95% CI 28.5-NR]) (univariate: HR 0.66, 95% CI 0.50-0.87, P = 0.003; multivariate: HR 0.58, 95% CI 0.39-0.86, P = 0.007), with comparable OS with PD-1 (multivariate, HR 0.90, 95% CI 0.48-1.70, P = 0.75). Similar findings were observed using a restricted-mean-survival-time model. Among those who experienced recurrence, the proportion of distant metastases was higher in the D/T cohort. D/T had a higher incidence of treatment modification due to adverse events (AEs) than PD-1, but fewer persistent AEs. Interpretation: In patients with stage III BRAF V600-mutant melanoma post definitive surgery, D/T yielded better RFS than PD-1, with higher transient but lower persistent toxicity, and comparable OS. D/T seems to provide a better outcome compared with PD-1, but a longer follow-up and ideally a large prospective trial are needed. Funding: Dr. Xue Bai was supported by the Beijing Hospitals Authority Youth Programme (QMS20211101) for her efforts devoted to this study. Dr. Keith T. Flaherty was funded by Adelson Medical Research Foundation for the efforts devoted to this study.

Burden of cancer trial participation: A qualitative sub-study of the INTERIM feasibility RCT.

OBJECTIVE: A qualitative sub-study was carried out within a larger phase II feasibility trial, to identify and describe the burden experienced by advanced melanoma patients participating in a clinical trial and the factors affecting their capacity to cope with the burden. METHODS: Semi-structured interviews were conducted with fourteen patients with advanced melanoma recruited from National Health Service hospitals in the United Kingdom. Qualitative analysis was undertaken using a framework analysis approach. Normalisation process theory was applied to the concept of research participation burden in order to interpret and categorise findings. RESULTS: Burdens of participation were identified as arising from making sense of the trial and treatment; arranging transport, appointment and prescriptions; enacting management strategies and enduring side effects; reflecting on trial documents and treatment efficacy, and emotional and mental effects of randomisation and treatment side effects. Factors reported as influencing capacity include personal attributes and skills, physical and cognitive abilities and support network. DISCUSSION: This is the first study to highlight the substantial burden faced by patients with advanced melanoma in a clinical trial and factors that may lessen or worsen the burden. Consideration of identified burdens during trial design and execution will reduce the burden experienced by research participants.

Flow cytometric measurable residual disease in adult acute myeloid leukemia: a preliminary report from Eastern India.

Presence of measurable residual disease (MRD) in acute myeloid leukemia (AML) is considered to be an independent predictor of relapse and poorer survival outcomes. MRD can be measured by flow cytometric, quantitative PCR, and NGS-based assays at varying sensitivities. There is scant Indian data on different aspects of MFC-MRD in AML including analysis strategies as well as molecular spectrum, clinical correlation, etc. This retrospective observational study included all newly diagnosed patients of acute myeloid leukemia in whom complete baseline diagnostic workup was available including flow cytometry and cytogenetic and molecular studies. Among patients with cytogenetic abnormalities (n = 25), no statistically significant correlation was observed between flow cytometric MRD positivity and presence of ≥ 3 mutations as well as relapsed disease. However, in AML patients with normal karyotype (n = 32), MRD positivity correlated strongly with relapsed status (p = 0.02), although no significant correlation was found with respect to FLT3 mutation, IDH mutation, NPM1 mutation, or complex genotype. Interestingly, 90.5% of MRD-positive patients belonged to ELN (2017) intermediate to high-risk category unlike only 9.5% in the good risk category (p = 0.0002). Median relapse-free survival was 8.5 months with a follow-up range of 3-24 months. On the basis of the observations of the present study, it can be clearly inferred that MRD status affects relapse status in the normal karyotype subgroup and can delineate patients who require stem cell transplantation in addition to molecular signatures.

Tumour infiltrating B cells discriminate checkpoint blockade-induced responses.

BACKGROUND: Immune cell-driven anti-cancer activity is paramount for effective responses to checkpoint inhibitors (ICB). However, the contribution of the different immune cell subsets in the circulation and within the tumour is poorly understood. MATERIALS AND METHODS: To elucidate the role of the different cell subsets in anti-tumour responses elicited by ICB, we performed single-cell analysis of the transcriptome and surface proteome of paired pre- and early on-treatment metastatic melanoma tumour biopsies and matched peripheral blood mononuclear cell samples. We next compared the survival of metastatic melanoma patients treated with ICB according to the abundance of pre-treatment tumour-infiltrating B cell clonotypes. RESULTS: We identified cell clusters associated with disease control or progression, defined differential expression of biological pathways likely involved in the immune awakening against the tumour and examined how cell-cell communication patterns between the tumour cell subsets change during treatment. Furthermore, we discovered that B cells (immunoglobulin expression and abundance of B cell clonotypes) discriminate the clinical response after ICB and propose that B cells likely contribute to anti-tumour immunity by antigen presentation through major histocompatibility complex molecules. Finally, we demonstrated that the abundance of tumour-infiltrating B cell clonotypes at baseline identifies two distinct risk groups, a finding that we confirmed in an independent cohort. CONCLUSIONS: Our exploratory translational study provides new insights on the mechanistic role of B cells in anti-melanoma immunity during treatment with ICB. Additionally, we support pre-treatment B cell tumour infiltration as a promising prognostic biomarker to be further validated as a tool for clinical risk stratification.

Delphi panel for consensus on the optimal management of dabrafenib plus trametinib-related pyrexia in patients with melanoma.

Purpose: Dabrafenib and trametinib combination therapy (dab + tram) is indicated to treat BRAF V600 mutation-positive unresectable/metastatic melanoma and as adjuvant treatment for resected stage III disease. Dab + tram-related pyrexia may require early therapy discontinuation. A modified Delphi panel was conducted to develop consensus on the optimal management of dab + tram-related pyrexia in patients with melanoma. Methods: In all, 10 UK oncologists experienced in melanoma management participated in a three-round modified Delphi study (Round 1: one-to-one interview; Rounds 2 and 3: email survey). In each round, participants rated the extent of their agreement with statements about defining and managing dab + tram-related pyrexia. Consensus was defined as >80% agreement for critical management (CM) and >60% for non-critical management (NCM) statements. Results: All 10 participants completed Round 1; 9 completed Rounds 2 and 3. Consensus was reached on 42/66 statements (20 CM and 22 NCM). Drug-related pyrexia was agreed as being strictly an elevation of body temperature, although other symptoms may be present (89% agreement). Panelists agreed on the need for simple and generic guidance on dab + tram-related pyrexia management that does not differentiate between patient groups (100%), and that management of first and second dab + tram-related pyrexia episodes should be the same regardless of treatment intent (100%). Regarding CM, participants agreed that both dab and tram should be interrupted for pyrexia (100%) without considering the use of steroids (89%); patients on dab + tram presenting to non-oncology services with pyrexia should be directed to an oncology-specific service as soon as possible and assessed for infection (100%). NCM statements on steroid use following dab + tram interruption and when to restart dab + tram did not reach consensus. Conclusions: These consensus statements provide a framework on optimal management of dab + tram-related pyrexia in patients with melanoma which should inform future guidelines.

Development of robust, indigenous ELISA for detection of IgG antibodies against CoV-2 N and S proteins: mass screening.

The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) pandemic has adversely affected humankind and caused millions of deaths globally since January 2020. Robust and quick serological tests such as antibody detection assays for SARS-CoV-2 provide relevant information and aid in the process of vaccine development and diagnostics, as well as in sero-epidemiological monitoring of antibody response to the virus. The receptor-binding domain (RBD) of spike and nucleocapsid protein are specific targets for detecting SARS-CoV-2 antibodies. Here, we present the development of a stable spike (S) and nucleocapsid (N) protein-based ELISA antibody detection test "CoroSuchak," with 99% sensitivity, 98% specificity, cost-effective, and detection in a minimum time for serodiagnosis and mass screening of the population for antibodies against SARS-CoV-2. Blood samples were analyzed from 374 SARS-CoV-2 reverse transcription-polymerase chain reaction (RT-PCR) positive, 772 negative and asymptomatic, and 874 random groups of subjects. We found that the antibody titer was significantly higher (p < 0.0001) in infected and vaccinated group compared to the only vaccinated and only infected group. Using enzyme-linked immunosorbent assay (ELISA), we detected SARS-CoV-2 immunoglobulin G (IgG) antibodies in 118/123 (96%) infected individuals, 570/653 (87%) non-infected but vaccinated individuals, 231/237 (97%) individuals who were both infected and vaccinated, and 499/874 (57%) from randomly selected individuals from the first and second waves of the pandemic. Similarly in the third wave, 14/14 (100%) infected and 16/20 (80%) RT-PCR-negative but symptomatic subjects were detected. Thus, the highly sensitive and specific in-house developed ELISA antibody detection kit "CoroSuchak" is extremely useful to determine the seroprevalence of SARS-CoV-2 antibodies in the coronavirus-exposed population. KEY POINTS: •Indigenous kit using a combination of spike and nucleocapsid proteins and peptide sequences. •High sensitivity and specificity to detect variants. •Highly sensitive for mass screening.

Patient and treatment characteristics of emergency presentations due to immune-mediated toxicities.

BACKGROUND: The prevalence of immune-mediated toxicities from immune checkpoint inhibitors (ICIs) is well described. However, the characteristics and treatment patterns for patients with emergency presentations owing to immune-mediated toxicity are less well known. MATERIALS AND METHODS: This study reviews all emergency presentations in patients treated with ICI at a single centre between May 2018 and March 2020. The aims were to describe and quantify patient and treatment characteristics, toxicity type and outcomes. RESULTS: 1165 patients were treated with ICI, and there were 597 emergency presentations in 370 patients. Of these, 191/597 (32%) were owing to an immune-mediated toxicity, median age was 64 years, and 127/191 (67%) were men. The most common tumour types were melanoma (53%) and lung cancer (22%), and the most common ICI received was ipilimumab + nivolumab combination immunotherapy (42%), followed by pembrolizumab monotherapy (21%) and nivolumab monotherapy (20%). The median number of cycles received was three (range 1-54), and 75/191 (39%) had previous ≥ grade 2 immune-mediated toxicity. 29% patients required second-line immunosuppression. The median time in the hospital was four days. There was a rising number of emergency presentations reflecting overall increasing use of ICI. CONCLUSIONS: Over a quarter of patients treated with ICI had an emergency presentation, and immune-mediated toxicity accounted for 32% of these. A diagnosis of melanoma, treatment with combination immunotherapy and previous ≥ grade 2 immune-mediated toxicity were common in patients with immune-mediated toxicity. These data allow better identification of patients likely to require admission and forward planning for acute oncology services.

Improved pyrexia-related outcomes associated with an adapted pyrexia adverse event management algorithm in patients treated with adjuvant dabrafenib plus trametinib: Primary results of COMBI-APlus.

BACKGROUND: COMBI-AD demonstrated long-term benefit of adjuvant dabrafenib plus trametinib in patients with resected stage III BRAF V600E/K-mutant melanoma; however, 9% of patients permanently discontinued therapy due to pyrexia. COMBI-APlus evaluated whether an adapted pyrexia management algorithm reduces high-grade pyrexia and pyrexia-related adverse outcomes. METHODS: COMBI-APlus is an open-label, phase IIIb trial evaluating an adapted pyrexia management algorithm in patients with high-risk resected stage III BRAF V600E/K-mutant melanoma treated with up to 12 months of adjuvant dabrafenib plus trametinib. Both drugs were interrupted for pyrexia (temperature ≥38°C) or the occurrence of pyrexia syndrome for suspected recurrent pyrexia. Treatment was restarted at the same dose once patients were symptom free for ≥24 h. The primary endpoint was the composite rate of grade 3/4 pyrexia, hospitalisation due to pyrexia, or permanent discontinuation due to pyrexia versus historical COMBI-AD control (20.0%; 95% confidence interval [CI], 16.3%-24.1%). RESULTS: At data cutoff (5 October 2020), COMBI-APlus met its primary endpoint of significant improvement in the composite rate of pyrexia (8.0% [95% CI, 5.9%-10.6%]), with rates of 3.8% for grade 3/4 pyrexia, 4.3% for hospitalisation due to pyrexia, and 2.4% for discontinuation due to pyrexia. Estimated 12-month relapse-free survival was 91.8% (95% CI, 89.0%-93.9%). The most common adverse events were consistent with those in COMBI-AD, and 14.7% of patients permanently discontinued treatment due to adverse events. CONCLUSIONS: The adapted pyrexia management algorithm appears to reduce the incidence of severe pyrexia outcomes, enables patients to manage pyrexia at home, and helps patients remain on treatment. CLINICAL TRIAL REGISTRATION: NCT03551626.

T cell immune awakening in response to immunotherapy is age-dependent.

BACKGROUND: Precision immuno-oncology approaches are needed to improve cancer care. We recently demonstrated that in patients with metastatic melanoma, an increase of clonality or diversity of the T cell receptor (TCR) repertoire of peripheral T cells following one cycle of immunotherapy is coincident with response to immune-checkpoint blockade (ICB). We also identified a subset of peripheral CD8+ immune-effector memory T cells (TIE cells) whose expansion was associated with response to ICB and increased overall survival. To improve our understanding of peripheral T cell dynamics, we examined the clinical correlates associated with these immune signatures. METHODS: Fifty patients with metastatic melanoma treated with first-line anti-PD-1 ICB were included. We analysed TCR repertoire and peripheral TIE cell dynamics by age before treatment (T0) and after the first cycle of treatment at week 3 (W3). RESULTS: We observed a correlation between TIE abundance and age at T0 (r = 0.40), which reduced following treatment at W3 (r = 0.07). However, at W3, we observed two significantly opposing patterns (p = 0.03) of TCR repertoire rearrangement in patients who responded to treatment, with patients ≥70 years of age showing an increase in TCR clonality and patients <70 years of age showing an increase in TCR diversity. CONCLUSIONS: We demonstrate that immunotherapy-induced immune-awakening patterns in patients with melanoma are age-related and may impact patient response to ICB, and thus have implications for biomarker development and planning of personalised therapeutic strategies.

The T cell receptor repertoire of tumor infiltrating T cells is predictive and prognostic for cancer survival.

Tumor infiltration by T cells is paramount for effective anti-cancer immune responses. We hypothesized that the T cell receptor (TCR) repertoire of tumor infiltrating T lymphocytes could therefore be indicative of the functional state of these cells and determine disease course at different stages in cancer progression. Here we show that the diversity of the TCR of tumor infiltrating T cell at baseline is prognostic in various cancers, whereas the TCR clonality of T cell infiltrating metastatic melanoma pre-treatment is predictive for activity and efficacy of PD1 blockade immunotherapy.

Tebentafusp, A TCR/Anti-CD3 Bispecific Fusion Protein Targeting gp100, Potently Activated Antitumor Immune Responses in Patients with Metastatic Melanoma.

PURPOSE: Tebentafusp is a first-in-class bispecific fusion protein designed to target gp100 (a melanoma-associated antigen) through a high affinity T-cell receptor (TCR) binding domain and an anti-CD3 T-cell engaging domain, which redirects T cells to kill gp100-expressing tumor cells. Here, we report a multicenter phase I/II trial of tebentafusp in metastatic melanoma (NCT01211262) focusing on the mechanism of action of tebentafusp. PATIENTS AND METHODS: Eighty-four patients with advanced melanoma received tebentafusp. Treatment efficacy, treatment-related adverse events, and biomarker assessments were performed for blood-derived and tumor biopsy samples obtained at baseline and on-treatment. RESULTS: Tebentafusp was generally well-tolerated and active in both patients with metastatic uveal melanoma and patients with metastatic cutaneous melanoma. A 1-year overall survival rate of 65% was achieved for both patient cohorts. On-treatment cytokine measurements were consistent with the induction of IFNγ pathway-related markers in the periphery and tumor. Notably, tebentafusp induced an increase in serum CXCL10 (a T-cell attractant) and a reduction in circulating CXCR3+ CD8+ T cells together with an increase in cytotoxic T cells in the tumor microenvironment. Furthermore, increased serum CXCL10 or the appearance of rash (likely due to cytotoxic T cells targeting gp100-expressing skin melanocytes) showed a positive association with patient survival. CONCLUSIONS: These data suggest that redirecting T cells using a gp100-targeting TCR/anti-CD3 bispecific fusion protein may provide benefit to patients with metastatic melanoma. Furthermore, the activity observed in these two molecularly disparate melanoma classes hints at the broad therapeutic potential of tebentafusp.

Emergency ambulatory outpatient management of immune-mediated hypophysitis.

PURPOSE: Immune-mediated hypophysitis is an important toxicity related to immune checkpoint inhibitors (ICI). Optimal management is associated with improved outcomes. It represents a wide spectrum of clinical presentations, and a proportion may be suitable for emergency ambulatory management. METHODS: Emergency ambulatory management of patients presenting with clinical features and findings consistent with ICI-induced hypophysitis was considered at a tertiary cancer/endocrinology hospital. Suitable patients were initially investigated and treated in accordance with the UK emergency management guidelines for ICI induced hypophysitis. After an initial observation period of 4 h, patients were discharged with oral hydrocortisone (20, 10, 10 mg). RESULTS: An initial cohort of 4 patients with emergency presentations of ICI-induced hypophysitis has been managed in an ambulatory fashion in the first 3 months. There were no 30-day readmissions. CONCLUSION: Carefully selected emergency presentations with immune-mediated hypophysitis may be suitable for ambulatory management.

Emergency presentations in patients treated with immune checkpoint inhibitors.

INTRODUCTION: Immune-mediated toxicities are potentially fatal and can affect virtually any organ system. The prevalence of immune-mediated toxicity in patients being treated with immune checkpoint inhibitors (ICIs) is well described. However, the reasons for presentation and the prevalence of immune-mediated toxicity in acutely unwell patients being treated with ICIs is less well described. MATERIALS AND METHODS: A prospective analysis of all emergency presentations in patients being treated with ICIs was performed at a specialist oncology hospital in England from 20th May 2018 to 19th May 2019. The primary outcome measure was whether the emergency presentation related to an immune-mediated toxicity. Secondary outcome measures were length of stay associated with immune-mediated toxicities and 7- and 30-day mortalities related to these presentations. RESULTS: During the study period, 300 patients on ICIs presented. The most common primary presenting complaints were dyspnoea 59 (19.7%), diarrhoea 47 (15.7%) and fever 37 (12.3%). Ninety-eight (32.7%) patients were diagnosed with an immune-mediated toxicity of which colitis 38 (38.8%), hepatitis 19 (19.4%) and pneumonitis 14 (14.3%) were the most common. The mean length of inpatient stay for those diagnosed with an immune-mediated presentation was 7.1 (0-45) days compared with 6.2 (0-44) days in those without. Seven patients died within 7 days of the emergency presentation, of whom 2 died from immune-mediated toxicity. CONCLUSIONS: One-third of cancer patients treated with ICIs admitted as an emergence had an immune-mediated toxicity and 2% died because of this. Acute care clinicians managing these patients need to be aware that immune-mediated toxicity is common in this patient population, but it can be challenging to differentiate these from other causes for emergency presentation.

Immune-awakening revealed by peripheral T cell dynamics after one cycle of immunotherapy.

Our understanding of how checkpoint inhibitors (CPI) affect T cell evolution is incomplete, limiting our ability to achieve full clinical benefit from these drugs. Here we analyzed peripheral T cell populations after one cycle of CPI and identified a dynamic awakening of the immune system revealed by T cell evolution in response to treatment. We sequenced T cell receptors (TCR) in plasma cell-free DNA (cfDNA) and peripheral blood mononuclear cells (PBMC) and performed phenotypic analysis of peripheral T cell subsets from metastatic melanoma patients treated with CPI. We found that early peripheral T cell turnover and TCR repertoire dynamics identified which patients would respond to treatment. Additionally, the expansion of a subset of immune-effector peripheral T cells we call TIE cells correlated with response. These events are prognostic and occur within 3 weeks of starting immunotherapy, raising the potential for monitoring patients responses using minimally invasive liquid biopsies."

A High-Sensitivity 10-Color Flow Cytometric Minimal Residual Disease Assay in B-Lymphoblastic Leukemia/Lymphoma Can Easily Achieve the Sensitivity of 2-in-106 and Is Superior to Standard Minimal Residual Disease Assay: A Study of 622 Patients.

BACKGROUND: Flow-cytometric minimal residual disease (FC-MRD) monitoring is a well-established risk-stratification factor in B-lymphoblastic leukemia/lymphoma (-B-ALL) and is being considered as a basis for deintensification or escalation in treatment protocols. However, currently practiced standard FC-MRD has limited sensitivity (up to 0.01%) and higher false MRD-negative rate. Hence, a highly sensitive, widely applicable, and easily reproducible FC-MRD assay is needed, which can provide a reliable basis for therapeutic modifications. METHODS: A 10-color high-event analysis FC-MRD assay was studied for the evaluation of MRD status at postinduction, (PI; day-35), postconsolidation, (PC; day-78), and subsequent follow-up time-points (SFU) in bone marrow samples from pediatric B-ALL. RESULTS: One-thousand MRD samples (PI-62.2%; PC-26.5%; and SFU-11.3%) from 622 childhood B-ALL patients were studied. High-event analysis was performed with median 4,452,000 events (range, 839,000 to 8,866,000 events) and >4 million events in 71% samples. MRD was measurable in 43.2% of PI-samples, in 29.4% PC-samples, and in 32.7% SFU-samples. To simulate comparison with standard FC-MRD, we reanalyzed MRD results gating only first 500,000 and first 1000,000 events in 122 PI-MRD positive samples with MRD levels <0.02%. Of these samples gated for 500,000 events and 1000,000 events, 32% and 21.3% were found to be falsely MRD-negative, respectively. CONCLUSIONS: We report an easily reproducible high-sensitivity 10-color FC-MRD assay with the sensitivity of 2-in-106 (0.0002%). It allowed the detection of low-level MRD in samples, which could have been reported negative using the standard FC-MRD with limited event analysis. Thus, this high-sensitivity MRD-methodology can provide a reliable basis for therapeutic modifications in B-ALL. © 2019 International Clinical Cytometry Society.