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EX VIVO DRUG RESPONSE PROFILING REVEALS UNIQUE SENSITIVITY PATTERNS AND OPPORTUNISTIC CANDIDATES FOR HIGH-RISK PEDIATRIC ACUTE MYELOID LEUKEMIA
Abstract
Background and Aims
Despite advances in chemotherapy-based protocols, the outcomes of pediatric acute myeloid leukemia (AML) remain suboptimal. Implementation of targeted therapy based on genomics is challenging due to the complex mutational patterns and scarcity of pharmacologic agents for most lesions. This study aims to adopt a functional approach that directly measure the response of patient-derived leukemic cells to targeted agents, and to establish the drug sensitivity pattern and identify candidates of immediate clinical relevance for precision usage in high-risk cases.
Methods
A high-throughput drug screen, comprising 39 targeted agents and 6 conventional chemotherapeutics, was performed on 25 pediatric AML samples using a serum-free, cytokine-supported culture system. The robustness of the drug testing platform for predicting in vivo activities was validated in animal models. Patients with refractory AML were treated with targeted agents based on drug profiling results, and assessed for clinical responses.
Results
Unsupervised clustering revealed 5 distinct clusters of drug response: highly active compounds (IC50<20nM, 6 drugs); generally active compounds (IC50<500nM, 11 drugs); compounds with bimodal activities (wide IC50 ranges, 4 drugs); generally inactive compounds (14 drugs); and inactive compounds (10 drugs). Targeted agents, including Bcl-2, HDAC, proteasome, HSP and survivin inhibitors, had substantially higher potency than standard chemotherapeutic agents. New agents approved for adult AML were essentially inactive in pediatric AML. Drug sensitivity ex vivo accurately predicted in vivo single-agent and combinatorial activities with cytarabine in cell line- and patient-derived xenografts. Administration of venetoclax and dasatinib to two patients with refractory AML resulted in rapid blast clearance and achieved long-term remission.
Conclusions
Our study establishes a pediatric-specific drug response profile of AML, which enables an evidence-based selection of targeted agents for patients without treatment options and endows therapies increasingly precise and personalized. It will ultimately impact the future design of clinical trials and protocols for managing high-risk pediatric AML.
THE TETRASPANIN CD9 IS A POTENT AND REACTIVATABLE TUMOR SUPPRESSOR IN PEDIATRIC ACUTE MYELOID LEUKEMIA
Abstract
Background and Aims
We recently identified the importance of CD9 on disease progression of acute lymphoblastic leukemia (ALL), but its role in acute myeloid leukemia (AML) remains unknown. This study aims to: (1) characterize CD9 expression in pediatric AML and its association with clinical outcomes; and (2) elucidate its regulations, functions and mechanisms.
Methods
Immunophenotypes of diagnostic BM were characterized by flow cytometry. Patients were stratified into CD9+ and CD9- subgroups for comparison of long-term survival. Epigenetic control of CD9 was investigated by bisulfite sequencing, and confirmed by decitabine treatment. Impact of CD9 on cell proliferation, division and chemosensitivity was measured by competition, colony and apoptosis assays. Influence of CD9 on leukemia progression was evaluated in xenograft models, coupled with single-cell transcriptomics to dissect the underlying mechanisms.
Results
CD9 expression on blasts of AML patients was significantly lower than that on stem cells of BM donors (12.2% vs. 48.4%). Among 64 AML cases, blasts of 24 patients (37.5%) were CD9+. The 5-year survival rates of CD9- patients were significantly lower than those of CD9+ patients (OS: 52.3% vs. 75.9%, RFS: 35.0% vs. 63.3%). Methylated CpG sites on CD9 promoter were more abundant in AML compared with ALL cell lines (14.5% vs. 4.7%). Decitabine treatment increased CD9 expression by 4.7-65.2-fold. Overexpression of CD9 reduced proliferation, division and clonogenicity of MV4-11 cells, and enhanced cytarabine-induced apoptosis. NOD/SCID mice transplanted with CD9+ cells exhibited a drastic reduction of leukemic load by 70.7-91.8%, concomitant with an increased expression of MHC molecules on leukemic cells, and infiltration of T cells and NK cells into the BM.
Conclusions
CD9 was epigenetically silenced in pediatric AML and conferred a dismal survival. Reexpression of CD9 substantially suppressed leukemia progression via immune sensitization. Our data established CD9 as a novel tumor suppressor in pediatric AML, which endow a huge translational potential.
A HOST-FACTOR BASED APPROACH IMPACTS SURVIVAL OF CHILDREN WITH ACUTE MYELOID LEUKEMIA (AML) AT HIGH-RISK FOR INDUCTION MORTALITY AND/OR EARLY TREATMENT ABANDONMENT
Abstract
Background and Aims
Lower middle-income countries face unique problems in the management of AML including delayed diagnosis and referral, severe socio-economic constraints(SSEC), and severe infections. We previously reported 10% induction-mortalities(IM) secondary to Multi-drug resistance organisms(MDRO) related sepsis or fungal pneumonia(FP) and 27% early treatment abandonment(ETA) from SSEC. With an aim to mitigate these adverse host-related factors(HFs), we offered oral metronomic chemotherapy(OMCT) as a bridge to intensive chemotherapy(IC).
Methods
Children ≤15-years of age with AML diagnosed between January-2014 and December-2017 were included. Baseline HFs screening included non-contrast Computerized-Tomography(NCCT) thorax and stool-surveillance culture. An assigned social-worker evaluated financial and supportive care needs. Patients with proven/probable FP and/or bacterial sepsis(Group-A), MDRO colonized(Group-B) or SSEC(Group-C), received group-specific interventions and initial OMCT [iOMCT: 4-weekly cycles of PrET (Prednisolone-40mg/m2, days 1-14(omitted for FP), Etoposide-50mg/m2qdand 6-TG-40mg/m2qd, days 1-21) till resolution and/or stabilization of HFs followed by IC-3+7(Anthracycline+Cytarabine) induction, 3-cycles of High-dose cytarabine(HIDAC), followed by maintenance-therapy(1year of OMCT). Response evaluation was by bone-marrow(BM) for morphology and minimal residual disease(MRD).
Results
Of 180 AML patients in the study period, 95(53%)- Group-A=43, Group-B=24, Group-C=27, received a median of 1(Range:1-5)cycle of iOMCT. Eleven could not progress to IC, 9 from Group A(7-Deaths, 2-progression), and 2-ETAs from Group-C. By end of iOMCT, 19(20%) attained bone-marrow morphological remission(Blasts<5%) of whom 7(7%) were BM-MRD<0.01% after a median of 1(Range:1-3)cycle. Seventy-two(86%) of 84 patients proceeding to IC attained BM-MRD<0.01% after 2-cycles. No relapsed/refractory patients could be transplanted. At a median follow-up of 25(Range:1-60)months, the 2-year Event-Free Survival and Overall Survival of patients who received iOMCT followed by IC(46.3±3.9% and 47.2±3.9% respectively) and patients who received IC upfront(52±5.6% and 53.3±5.6% respectively) were comparable.
Conclusions
The use of initial OMCT provides an opportunity to deliver intensive chemotherapy in patients who are at high-risk for induction mortality and early treatment abandonment, and mitigates adverse host-factors allowing outcomes comparable to those receiving standard of care.
DISMAL OUTCOME OF PEDIATRIC ACUTE MYELOID LEUKEMIA IN A LARGE REFERRAL CENTER IN WESTERN KENYA: EXPERIENCES OF A LOWER-MIDDLE-INCOME COUNTRY
Abstract
Background and Aims
Survival of pediatric acute myeloid leukemia (AML) in low- and middle-income countries (LMICs) is poor. Moi Teaching and Referral Hospital (MTRH) in Eldoret is the only academic hospital in Western Kenya treating childhood cancer. Aim: To evaluate recent outcome of pediatric AML patients at MTRH.
Methods
Medical records of 71 children (0-18 years) diagnosed between January 2010 and December 2018 with de novo AML were studied using the childhood cancer registry at MTRH, available since 2010. AML diagnosis was mainly based on morphology, cytogenetic studies were unavailable. Treatment comprised two induction courses (7+3; cytarabine, doxorubicin), two consolidation courses (5+3; cytarabine, etoposide), and triple intrathecal therapy at each course (methotrexate, hydrocortisone, cytarabine). Stem cell transplantation was unavailable. Baseline characteristics were studied and Kaplan-Meier methods were used to estimate probabilities of event-free survival (pEFS) and overall survival (pOS).
Results
Forty-one patients were male (57.7%). Median age at diagnosis was 8.7 years (1.2-15). Four patients died before onset of treatment. Twelve patients only received palliative care. Twenty-four of the 55 patients who started treatment died before day 42 (43.6%). Five patients abandoned treatment before day 42. Early death (ED) rate was 63.4%, including the latter five abandoned patients and sixteen patients who did not start chemotherapy. Seventeen patients achieved complete remission (CR) (30.9%) of whom seven relapsed (41.2%). Treatment-related mortality (TRM) occurred in three patients. Abandonment rate was 25.4% (n=18). Seven patients are assumed to be in continuous CR with a median follow-up duration of 6.1 months (0.3-46.9), but six of them are lost to follow-up. Two-year pEFS and pOS were 5% ±3.1% and 11.3% ±5.1%, respectively.
Conclusions
Survival of pediatric AML in Western Kenya is poor, due to high ED, TRM and relapse rates. Priority in improving survival should be improvement of supportive care. Furthermore, reasons of abandonment should be studied to lower the rate.