Treatment and follow-up of children with chronic myeloid leukaemia in chronic phase (CML-CP) in the tyrosine kinase inhibitor (TKI) era-Two decades of experience from the Tata Memorial Hospital paediatric CML (pCML) cohort.

Tyrosine kinase inhibitors (TKIs) have drastically improved the outcomes of pCML (paediatric CML) but data on long-term off-target toxicities of TKIs in children are scarce. In this single-centre, retrospective cum prospective study of pCML in chronic phase, we report our experience of treating 173 children with imatinib and following them for long-term toxicities. Mean (SD) time to attain CHR, CCyR and MMR were 3.05 (2.1), 10.6 (8.4) and 43.4 (31.8) months respectively. DMR was not attained in 59 (34%) patients at last follow-up. Ten patients were switched to second-generation TKIs (2G-TKIs; nilotinib = 1/dasatinib = 9) due to poor/loss in response, of which seven had kinase domain mutations. Three patients progressed to the blastic phase. At a median follow-up of 84 (3-261) months, the 5-year EFS and OS for the entire cohort were 96.9% (95% CI: 93.4-100) and 98.7% (95% CI: 96.9-100) respectively. Screening for long-term toxicities revealed low bone density and hypovitaminosis D in 70% and 80% respectively. Other late effects included short stature (27%), delayed puberty (15%), poor sperm quality (43%) and miscellaneous endocrinopathies (8%). Children younger than 5 years at diagnosis were more susceptible to growth and endocrine toxicities (p = 0.009). Regular monitoring for long-term toxicities, timely intervention and trial of discontinuation whenever feasible are likely to improve the long-term outlook of pCML.

15-color highly sensitive flow cytometry assay for post anti-CD19 targeted therapy (anti-CD19-CAR-T and blinatumomab) measurable residual disease assessment in B-lymphoblastic leukemia/lymphoma: Real-world applicability and challenges.

OBJECTIVES: Measurable residual disease (MRD) is the most relevant predictor of disease-free survival in B-cell acute lymphoblastic leukemia (B-ALL). We aimed to establish a highly sensitive flow cytometry (MFC)-based B-ALL-MRD (BMRD) assay for patients receiving anti-CD19 immunotherapy with an alternate gating approach and to document the prevalence and immunophenotype of recurrently occurring low-level mimics and confounding populations. METHODS: We standardized a 15-color highly-sensitive BMRD assay with an alternate CD19-free gating approach. The study included 137 MRD samples from 43 relapsed/refractory B-ALL patients considered for anti-CD19 immunotherapy. RESULTS: The 15-color BMRD assay with CD22/CD24/CD81/CD33-based gating approach was routinely applicable in 137 BM samples and could achieve a sensitivity of 0.0005%. MRD was detected in 29.9% (41/137) samples with 31.7% (13/41) of them showing <.01% MRD. Recurrently occurring low-level cells that showed immunophenotypic overlap with leukemic B-blasts included: (a) CD19+CD10+CD34+CD22+CD24+CD81+CD123+CD304+ plasmacytoid dendritic cells, (b) CD73bright/CD304bright/CD81bright mesenchymal stromal/stem cells (CD10+) and endothelial cells (CD34+CD24+), (c) CD22dim/CD34+/CD38dim/CD81dim/CD19-/CD10-/CD24- early lymphoid progenitor/precursor type-1 cells (ELP-1) and (d) CD22+/CD34+/CD10heterogeneous/CD38moderate/CD81moderate/CD19-/CD24- stage-0 B-cell precursors or ELP-2 cells. CONCLUSIONS: We standardized a highly sensitive 15-color BMRD assay with a non-CD19-based gating strategy for patients receiving anti-CD19 immunotherapy. We also described the immunophenotypes of recurrently occurring low-level populations that can be misinterpreted as MRD in real-world practice.

KIT exon 17 mutations are predictive of inferior outcome in pediatric acute myeloid leukemia with RUNX1::RUNX1T1.

BACKGROUND: Pediatric core binding factor acute myeloid leukemia (CBF-AML), although considered a favorable risk subtype, exhibits variable outcomes primarily driven by additional genetic abnormalities, such as KIT mutations. PROCEDURE: In this study, we examined the prognostic impact of KIT mutations in 130 pediatric patients with CBF-AML, treated uniformly at a single center over 4 years (2017-2021). KIT mutations were detected via next-generation sequencing using a myeloid panel comprising 52 genes for most patients. RESULTS: Our findings revealed that KIT mutations were present in 31% of CBF-AML cases. Exon 17 KIT mutation was most commonly (72%) seen with notable occurrences at the D816 and N822 residue in 48% and 39% of cases, respectively. The 3-year cumulative incidence of relapse (CIR) and overall survival (OS) for patients with exon 17 KIT mutation were 36% and 40%, respectively, and was significantly worse in comparison to other site KIT mutations (3-year CIR: 11%; OS: 64%) and without KIT mutation (3-year CIR: 13%; OS:71%). Notably, the prognostic impact of KIT mutations was prominent in patients with RUNX1::RUNX1T1, but not in those with CBFB::MYH11 fusion. Additionally, a high KIT variant-allele frequency (VAF) (>33%) predicted for a higher disease relapse; 3-year CIR of 40% for VAF greater than 33% versus 7% for VAF less than 33%. When adjusted for site of KIT mutation and end-of-induction measurable residual disease, VAF greater than 33% correlated with poor OS (hazard ratio [HR]: 4.4 [95% CI: 1.2-17.2], p = .034). CONCLUSION: Exon 17 KIT mutations serve as an important predictor of relapse in RUNX1::RUNX1T1 pediatric AML. In addition, a high KIT VAF may predict poor outcomes in these patients. These results emphasize the need to incorporate KIT mutational analysis into risk stratification for pediatric CBF-AML.

United we stand, divided we fall. Multicentre standardization of measurable residual disease assessment in acute leukaemia is the way forward.

Assessment of measurable residual disease (MRD) using multiparameter flow cytometry in precursor B-cell acute lymphoblastic leukaemia (ALL) is routine. However, studies on the harmonization of laboratory techniques as well as on the interpretation of results are limited. Here, Ikoma-Colturato and colleagues from Brazil demonstrate multicentric standardization of B-ALL MRD using EuroFlow protocols. Commentary on: Ikoma-Colturato et al., Multicentric standardization of minimal/measurable residual disease in B-cell precursor acute lymphoblastic leukaemia using next-generation flow cytometry in a low/middle-level income country. Br J Haematol 2023;200:381-384.

Treating relapsed B cell-precursor ALL in children with a setting-adapted mitoxantrone-based intensive chemotherapy protocol (TMH rALL-18 PROTOCOL) - experience from Tata Memorial Hospital, India.

The outlook of relapsed ALL in low- and middle-income countries (LMICs) is dismal due to high treatment-related toxicities and inadequate resources. We report our experience of using a locally adapted mitoxantrone-based protocol for non-high risk (HR) relapsed B-ALL (rALL). A retrospective cum prospective study of standard and intermediate risk (SR and IR) rALL patients treated on TMH rALL-18 protocol (adapted from COG/UKALLR3/Int-Re-ALL protocols) between November 2018 and January 2021 was analyzed. The protocol comprising of 7 blocks of multi-agent chemotherapy including mitoxantrone in induction followed by local irradiation and maintenance, underwent serial modifications based on our experience with initial patients. Eighty-two patients (SR rALL, 3; IR rALL, 79) were treated on TMH rALL-18 protocol. Of 321 grade 3/4 reported toxicities, around 43% (138 toxicities) were noted during induction. Induction chemotherapy was outpatient-based; however, 68 patients (82.9%) required supportive care admissions. Twelve out of 19 patients with gram negative bacilli sepsis (included 7 MDRO) died during reinduction. Five remission deaths were seen during block 3 after which cytarabine was dose reduced (3 g to 2 g/m2). Post-reinduction minimal residual disease was negative in 54 (80.6%) out of 67 evaluable patients. At a median follow-up of 24 months (95% CI 22-27), the estimated 2-year event-free and overall survival of the entire cohort was 58% (95% CI 48.1-69.9) and 60.3% (95% CI 50.5-72). Until the time, targeted therapies are freely accessible in LMICs, strengthening supportive care as well as local adaptation of protocols that strike a fine balance between efficacy and tolerability are mandated.

Mimics and artefacts of measurable residual disease in a highly sensitive multicolour flow cytometry assay for B-lymphoblastic leukaemia/lymphoma: critical consideration for analysis of measurable residual disease.

High-sensitivity multicolour flow cytometry (MFC)-based B-lymphoblastic leukaemia (B-ALL) measurable residual disease (BMRD) assay is increasingly being used in clinical practice. Herein, we describe six consistently present low-level populations immunophenotypically mimicking abnormal B-ALL blasts in 441 BMRD samples from 301 children. These included CD19+ CD123+ plasmacytoid dendritic cells differentiating from lymphoid precursors, CD10+ transitional B cells with CD10+ /CD38dim-to-negative/CD20bright/CD45bright phenotype, CD19+ natural killer (NK) cells, CD73bright/CD10+ mesenchymal stromal/stem cells, CD73bright/CD34+ endothelial cells, and a CD34+ CD38dim-to-negative/CD10- /CD20bright/CD45bright subset of mature B cells. We provide the proportions, comprehensive immunophenotype, and practical clues for proper identification of these low-level populations. Knowledge regarding the presence and immunophenotype of these mimics is essential for accurate interpretation in high-sensitivity MFC-BMRD analysis.

Comprehensive immune cell profiling depicts an early immune response associated with severe coronavirus disease 2019 in cancer patients.

Recent studies have highlighted multiple immune perturbations related to severe acute respiratory syndrome coronavirus 2 infection-associated respiratory disease [coronavirus disease 2019 (COVID-19)]. Some of them were associated with immunopathogenesis of severe COVID-19. However, reports on immunological indicators of severe COVID-19 in the early phase of infection in patients with comorbidities such as cancer are scarce. We prospectively studied about 200 immune response parameters, including a comprehensive immune-cell profile, inflammatory cytokines and other parameters, in 95 patients with COVID-19 (37 cancer patients without active disease and intensive chemo/immunotherapy, 58 patients without cancer) and 21 healthy donors. Of 95 patients, 41 had severe disease, and the remaining 54 were categorized as having a nonsevere disease. We evaluated the association of immune response parameters with severe COVID-19. By principal component analysis, three immune signatures defining characteristic immune responses in COVID-19 patients were found. Immune cell perturbations, in particular, decreased levels of circulating dendritic cells (DCs) along with reduced levels of CD4 T-cell subsets such as regulatory T cells (Tregs ), type 1 T helper (Th1) and Th9; additionally, relative expansion of effector natural killer (NK) cells were significantly associated with severe COVID-19. Compared with patients without cancer, the levels of terminal effector CD4 T cells, Tregs , Th9, effector NK cells, B cells, intermediate-type monocytes and myeloid DCs were significantly lower in cancer patients with mild and severe COVID-19. We concluded that severely depleted circulating myeloid DCs and helper T subsets in the initial phase of infection were strongly associated with severe COVID-19 independent of age, type of comorbidity and other parameters. Thus, our study describes the early immune response associated with severe COVID-19 in cancer patients without intensive chemo/immunotherapy.

Genomic Analysis of AZD1222 (ChAdOx1) Vaccine Breakthrough Infections in the City of Mumbai.

Background: This manuscript describes the genetic features of SARS-CoV-2 mutations, prevalent phylogenetic lineages, and the disease severity amongst COVID-19-vaccinated individuals in a tertiary cancer hospital during the second wave of the pandemic in Mumbai, India. Methods: This observational study included 159 COVID-19 patients during the second wave of the pandemic from 17th March to 1st June 2021 at a tertiary cancer care centre in Mumbai. The cohort comprised of healthcare workers, staff relatives, cancer patients, and patient relatives. For comparison, 700 SARS-CoV-2 genomes sequenced during the first wave (23rd April to 25th September 2020) at the same centre were also analysed. Patients were assigned to nonvaccinated (no vaccination or <14 days from the 1st dose, n = 92), dose 1(≥14 days from the 1st dose to <14 days from the 2nd dose, n = 29), and dose 2 (≥14 days from the 2nd dose, n = 38) groups. Primary measure was the prevalence of SARS-CoV-2 genomic lineages among different groups. In addition, severity of COVID-19 was assessed according to clinical and genomic variables. Results: Kappa B.1.1671.1 and delta B.1.617.2 variants contributed to an overwhelming majority of sequenced genomes (unvaccinated: 40/92, 43.5% kappa, 46/92, 50% delta; dose 1: 14/29, 48.3% kappa, 15/29, 51.7% delta; and dose 2: 23/38, 60.5% kappa, 14/38 36.8% delta). The proportion of the kappa and delta variants did not differ significantly across the unvaccinated, dose 1, and dose 2 groups (p = 0.27). There was no occurrence of severe COVID-19 in the dose 2 group (0/38, 0% vs. 14/121, 11.6%; p = 0.02). SARS-CoV-2 genomes from all three severe COVID-19 patients in the vaccinated group belonged to the delta lineage (3/28, 10.7% vs. 0/39, 0.0%, p = 0.04). Conclusions: Sequencing analysis of SARS-COV-2 genomes from Mumbai during the second wave of COVID-19 suggests the prevalence of the kappa B.1.617.1 and the delta B.1.627.2 variants among both vaccinated and unvaccinated individuals. Continued evaluation of genomic sequencing data from breakthrough COVID-19 is necessary for monitoring the properties of evolving variants of concern and formulating appropriate immune response boosting and therapeutic strategies.

Clinical course of severe COVID19 treated with tocilizumab and antivirals post-allogeneic stem cell transplant with extensive chronic GVHD.

Recipients of allogeneic hematopoietic stem cell transplantation (allo-HSCT) are an immunocompromised group who are likely to develop severe complications and mortality because of coronavirus disease 2019 (COVID-19). We report here a 61-year-old male patient of primary myelofibrosis who underwent an allo-HSCT 6 years earlier, had chronic graft-versus-host disease (cGVHD) involving the liver, lung, eyes, and skin, (with recurrent episodes of pulmonary infections) who developed severe COVID-19. The patient was treated with tocilizumab, and a combination of lopinavir/ritonavir, ribavirin, interferon-ß1b. He was discharged after 31 days with full recovery. Tocilizumab, a humanized monoclonal antibody against IL6, has been shown to benefit respiratory manifestations in severe COVID19. However, this is first report, to our knowledge, of its use and benefit in a post HSCT recipient.

Detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is influenced by the type of transport medium: Implications for diagnosis and monitoring.

It is unclear if the use of a molecular transport medium (MTM) containing guanidine isothiocyanate (GITC) would be advantageous over the CDC recommended, commonly used viral transport medium (VTM). We retested 70 SARS-CoV2 cases by RT-PCR in varying stages of follow-up using MTM and VTM in parallel and found discrepant results of RNase P, E and N genes. Majority (81%) patients tested positive with MTM as compared with VTM (27.1%). Even patients who were sampled 3 weeks after diagnosis demonstrated a significant discrepancy in the positivity rates between MTM vs VTM raising concerns about the clinical utility of VTM.

Investigating the clinical, hematological and cytogenetic profile of endoreduplicated hypodiploids in BCP-ALL.

Ploidy, besides known translocations in lymphoblasts, is a strong predictor of prognosis in B- cell progenitor acute lymphoblastic leukemia (BCP-ALL). While hyperdiploidy with >50 chromosomes shows a favourable outcome, hypodiploidy with <45 chromosomes have a dismal clinical outcome. However, there exists a small subset where both the hypodiploid and hyperdiploid clones are apparent either by cytogenetics or flow cytometry and are defined partially masked hypodiploids or mosaics based on the percentage of clonal population. These patients are essentially hypodiploids, and show the hyperdiploid clone as a consequence of endoreduplication of the primary hypodiploid clone- A phenomenon of successive replication of genome without mitosis (cytokinesis) resulting in increased ploidy. In the current study, we present the complete clinical, hematological and cytogenetic profile of 11 such newly diagnosed mosaics or partially masked hypodiploid BCP-ALL cases.

Over expression of brain and acute leukemia, cytoplasmic and ETS-related gene is associated with poor outcome in acute myeloid leukemia.

The high expression of brain and acute leukemia, cytoplasmic (BAALC) and ETS-related gene (ERG) has been reported to influence the outcome in acute myeloid leukemia (AML), but due to limited prospective studies, their role as prognostic factors is unclear. At diagnosis, the prognostic value of BAALC and ERG expression with respect to other cytogenetic and molecular markers was analyzed in 149 AML patients. Patients were divided into quartiles which resulted in the formation of four groups (G1-G4) based on expression values of BAALC and ERG and clinical response defined across groups. Groups with similar survival probabilities were merged together and categorized subsequently as high versus low expressers. Patients with high BAALC and ERG expression had significantly lower overall survival (OS; BAALC: p = 0.001 at 5 years 29.4% vs. 69.8%; ERG: p < 0.0001 at 5 years 4% vs. 50.4%) and disease-free survival (BAALC: p = 0.001 at 5 years 19.5% vs. 69.8%; ERG: p < 0.0001 at 5 years 4.2% vs. 47%). Patients were further stratified combining BAALC and ERG expression in an integrative prognostic risk score (IPRS). After a median follow-up of 54 months (95% CI 45-63 months) among survivors, IPRS for high versus low expressers was a significant predictor for OS (BAALC + ERG: 4% vs. 71.6%, p < 0.0001) and DFS (BAALC + ERG: 4.5% vs. 74.1%, p < 0.0001). In a multivariate model, IPRS of BAALC + ERG expression retained prognostic significance for OS (hazard ratio [HR] 2.96, 95%CI 1.91-4.59, p < 0.001) and DFS (HR 3.61, 95%CI 2.26-5.76, p < 0.001).

Mandatory preoperative COVID-19 testing for cancer patients-Is it justified?

BACKGROUND: Severe acute respiratory syndrome coronavirus 2 has caused substantial disruptions in routine clinical care. Emerging data show that surgery in coronavirus disease (COVID)-positive cases can be associated with worsening of clinical outcomes and increased postoperative mortality. Hence, preoperative COVID-19 testing for all patients before elective surgery was implemented in our institution. MATERIALS AND METHODS: Two hundred and sixty-two asymptomatic cancer patients were preoperatively tested for COVID-19 using reverse-transcription polymerase chain reaction technique with nasopharyngeal and oropharyngeal swabbing. All negative patients were operated within 72 hours, and positive patients were quarantined for a minimum 14 days before re-swabbing. RESULTS: In our cohort, 21 of 262 (8.0%) asymptomatic preoperative patients, who were otherwise fit for surgery, tested positive. After adequate quarantine and a negative follow-up test report, 12 of 21 (57%) had an operation. No major postoperative morbidity due to COVID-19 was noted during the immediate postoperative period before discharge from the hospital. CONCLUSION: Routine preoperative COVID-19 testing was successful in identifying asymptomatic viral carriers. There was no incidence of symptomatic COVID-19 disease in the postoperative period, and there was no incidence of morbidity attributable to COVID-19. These data suggested a beneficial role for mandatory preoperative COVID-19 testing.

Clinicoepidemiologic Profile and Outcome Predicted by Minimal Residual Disease in Children With Mixed-phenotype Acute Leukemia Treated on a Modified MCP-841 Protocol at a Tertiary Cancer Institute in India.

INTRODUCTION: Mixed-phenotype acute leukemia (MPAL) accounts for 1.2% to 5% of acute leukemia across age groups with intermediate prognosis. We evaluated clinicoepidemiologic profiles and outcomes of MPAL. METHODS: Records of children younger than 15 years of age with acute leukemia from January 2010 to December 2016 were reviewed on the basis of the MPAL WHO 2008 criteria. Treatment was uniform with a modified MCP-841 protocol. Descriptive analysis tools were used. Outcomes were measured by the Kaplan-Meier method on MedCalc, version 14.8.1. RESULTS: Among 3830 children with acute leukemia in the study period, 2892 received treatment from our center, of whom 24 (0.83%) had MPAL, median age 9 years, with a male:female ratio of 3:1, and median white blood cell of 13.4×10/L. Common immunophenotypes were B/myeloid-12 (50%), T/myeloid-9 (37.5%), and B/T-lymphoid-3 (12.5%). Some B/myeloid cases had abnormal cytogenetics. Seventeen patients were evaluable for outcome. Sixteen patients underwent postinduction bone marrow and 13 (81%) achieved morphologic remission. Thirteen patients underwent flow cytometry-based minimal residual disease evaluation; 9 (69%) were <0.01% (4 postinduction, 5 postconsolidation), and 67% of these had sustained remission till the last follow-up. None underwent bone marrow transplant. The projected 3-year event-free and overall survival rates were 40% and 48%, respectively (median follow-up: 22 mo). CONCLUSION: MPAL represented <1% of childhood acute leukemia. acute lymphoblastic leukemia-type chemotherapy that incorporated high-dose cytarabine was effective in achieving an minimal residual disease-negativity rate of 69% in evaluated patients, which was also predictive of better outcome.

A novel and easy FxCycle™ violet based flow cytometric method for simultaneous assessment of DNA ploidy and six-color immunophenotyping.

Abnormal DNA ploidy is a valuable prognostic factor in many neoplasms, especially in hematological neoplasms like B-cell acute lymphoblastic leukemia (B-ALL) and multiple myeloma (MM). Current methods of flow-cytometric (FC) DNA-ploidy evaluation are either technically difficult or limited to three- to four-color immunophenotyping and hence, challenging to evaluate DNA-ploidy in minute tumor population with background rich of its normal counterpart cells and other hematopoietic cells. We standardized a novel sensitive and easy method of simultaneous evaluation of six- to seven-color immunophenotyping and DNA-ploidy using a dye-FxCycle Violet (FCV). Linearity, resolution, and coefficient of variation (CV) for FCV were studied using chicken erythrocyte nuclei. Ploidy results of FCV were compared with Propidium iodide (PI) in 20 samples and intra-assay variation for FCV was studied. Using this six-color immunophenotyping & FCV-protocol DNA-ploidy was determined in bone-marrow samples from 124 B-ALL & 50 MM patients. Dilution experiment was also conducted to determine the sensitivity in detection of aneuploidy in minute tumor population. FCV revealed high linearity and resolution in 450/50 channel. On comparison with PI, CV of Go/G1-peak with FCV (mean-CV 4.1%) was slightly higher than PI (mean-CV 2.9%) but had complete agreement in ploidy results. Dilution experiment showed that aneuploidy could be accurately detected up to the limit of 0.01% tumor cells. Intra-assay variation was very low with CV of 0.005%. In B-ALL, hypodiploidy was noted in 4%, hyperdiploidy in 24%, near-hyperdiploidy in 13% and remaining 59% were diploid. In MM, hypodiploidy was in 2%, hyperdiploidy in 58%, near-hyperdiploidy in 8% and remaining 30% were diploid. FCV-based DNA-ploidy method is a sensitive and easy method for simultaneous evaluation of six-color immunophenotyping and DNA analysis. It is useful in DNA-ploidy evaluation of minute tumor population in cases like minimal residual disease and MM precursor conditions.

Circulating tumor plasma cells and peripheral blood measurable residual disease assessment in multiple myeloma patients not planned for upfront transplant.

Circulating tumor plasma cells (CTPCs) provide a noninvasive alternative for measuring tumor burden in newly diagnosed multiple myeloma (NDMM). Moreover, measurable residual disease (MRD) assessment in peripheral blood (PBMRD) can provide an ideal alternative to bone marrow MRD, which is limited by its painful nature and technical challenges. However, the clinical significance of PBMRD in NDMM still remains uncertain. Additionally, data on CTPC in NDMM patients not treated with transplant are scarce. We prospectively studied CTPC and PBMRD in 141 NDMM patients using highly sensitive multicolor flow cytometry (HS-MFC). PBMRD was monitored at the end of three cycles (PBMRD1) and six cycles (PBMRD2) of chemotherapy in patients with detectable baseline CTPC. Patients received bortezomib-based triplet therapy and were not planned for an upfront transplant. Among baseline risk factors, CTPC ≥ 0.01% was independently associated with poor progression-free survival (PFS) (hazard ratio [HR] = 2.77; p = 0.0047) and overall survival (OS) (HR = 2.9; p = 0.023) on multivariate analysis. In patients with detectable baseline CTPC, undetectable PBMRD at both subsequent time points was associated with longer PFS (HR = 0.46; p = 0.0037), whereas detectable PBMRD at any time point was associated with short OS (HR = 3.25; p = 0.004). Undetectable combined PBMRD (PBMRD1 and PBMRD2) outperformed the serum-immunofixation-based response. On multivariate analysis, detectable PBMRD at any time point was independently associated with poor PFS (HR = 2.0; p = 0.025) and OS (HR = 3.97; p = 0.013). Thus, our findings showed that CTPC and PBMRD assessment using HS-MFC provides a robust, noninvasive biomarker for NDMM patients not planned for an upfront transplant. Sequential PBMRD monitoring has great potential to improve the impact of the existing risk stratification and response assessment models.

Treatment of Pediatric Acute Promyelocytic Leukemia with Retinoic Acid and Arsenic Trioxide along with Chemotherapy.

OBJECTIVES: Outcomes of childhood acute promyelocytic leukemia (APL) have exceeded 90% in the era of differentiating agents. In resource-limited settings, early mortality secondary to coagulopathy remains a significant challenge. Differentiation syndrome is a unique complication of APL therapy that requires a high degree of suspicion for timely initiation of therapy. METHODS: A retrospective study of children ≤15 y of age with APL diagnosed between January-2013 and June-2019 treated at a tertiary cancer centre was conducted. Patients with a total leukocyte count ≥10,000/µL were risk stratified as high-risk. Treatment included differentiating agents, all-trans retinoic acid and arsenic trioxide along with chemotherapy. Baseline demographics, clinical complications and outcomes were analysed. RESULTS: Out of 90 patients treated, 48 (53%) had high-risk APL and 25 (28%) presented with significant bleeding manifestations. Response to therapy was excellent with 96% of evaluable patients achieving molecular remission by the end of consolidation phase. Differentiation syndrome occurred in 23 (25%) patients of which two expired. Early mortality rate was 5.5% and was due to severe hemorrhage most often at the time of presentation. The 3-y overall survival of the entire cohort was 91% (95% CI: 85-97%). Two of 4 patients with relapse of disease could be salvaged with only differentiating agents followed by autologous transplantation. CONCLUSIONS: Long-term outcomes of Indian children with APL are excellent. Timely management of coagulopathy and prompt initiation of differentiating agents along with appropriate cytoreductive measures is critical. Efforts to build academic-community partnerships to ensure timely diagnosis and emergency care in order to reduce early mortality are needed.

Novel covalent CDK7 inhibitor potently induces apoptosis in acute myeloid leukemia and synergizes with Venetoclax.

INTRODUCTION: The emergence of resistance to the highly successful BCL2-directed therapy is a major unmet need in acute myeloid leukemia (AML), an aggressive malignancy with poor survival rates. Towards identifying therapeutic options for AML patients who progress on BCL2-directed therapy, we studied a clinical-stage CDK7 inhibitor XL102, which is being evaluated in solid tumors (NCT04726332). MATERIALS AND METHODS: To determine the anti-proliferative effects of XL102, we performed experiments including time-resolved fluorescence resonance energy transfer, target occupancy, cell cycle and apoptosis-based assays. We also included genetically characterized primary myeloid blasts from de novo and relapsed/refractory AML patients. For mechanistic studies, CRISPR/Cas9 mediated knockout of CDK7 and c-Myc and immunoblotting were performed. NOD/SCID orthotropic and subcutaneous AML xenografts were used to determine anti-leukemic effects. To assess the synergistic effects of XL102 with Venetoclax, we performed RNA sequencing and gene set enrichment analysis using Venetoclax sensitive and resistant model systems. RESULTS: XL102, a highly specific, orally bioavailable covalent inhibitor of CDK7. Inhibitory effect on CDK7 by XL102 in primary myeloid blasts (n = 54) was in nanomolar range (mean = 300 nM; range = 4.0-952 nM). XL102 treated AML cells showed a reduction in phosphorylation levels of Serine 2/5/7 at carboxy-terminal domain of RNA polymerase II. T-loop phosphorylation of CDK1(Thr161) and CDK2(Thr160) was inhibited by XL102 in dose-dependent manner leading to cell-cycle arrest. c-Myc downregulation and enhanced levels of p53 and p21 in XL102 treated cells were observed. Increased levels of p21 and activation of p53 by XL102 were mimicked by genetic ablation of CDK7, which supports that the observed effects of XL102 are due to CDK7 inhibition. XL102 treated AML xenografts showed remarkable reduction in hCD45 + marrow cells (mean = 0.60%; range = 0.04%-3.53%) compared to vehicle control (mean = 38.2%; range = 10.1%-78%), with corresponding increase in p53, p21 and decrease in c-Myc levels. The data suggests XL102 induces apoptosis in AML cells via CDK7/c-Myc/p53 axis. RNA-sequencing from paired Venetoclax-sensitive and Venetoclax-resistant cells treated with XL102 showed downregulation of genes involved in proliferation and apoptosis. CONCLUSION: Taken together, XL102 with Venetoclax led to synergistic effects in overcoming resistance and provided a strong rationale for clinical evaluation of XL102 as a single agent and in combination with Venetoclax.