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Monosomy 7 and del(7q) (-7/-7q) are frequent chromosomal abnormalities detected in up to 10% of acute myeloid leukemia (AML) patients. Despite unfavorable treatment outcomes, no approved targeted therapies exist for patients with -7/-7q. Therefore, we aimed to identify novel therapeutic vulnerabilities in AML with -7/-7q. Through an analysis of data from ex vivo drug screens in 270 primary AML samples, we discovered that -7/-7q AML cells are highly sensitive to the inhibition of nicotinamide phosphoribosyltransferase (NAMPT). NAMPT is a rate-limiting enzyme in the NAD+ salvage pathway. Mechanistically, theNAMPTgene is located at 7q22.1, and deletion of one copy due to -7/-7q results inNAMPThaploinsufficiency. This leads to reduced gene expression and a therapeutically targetable vulnerability to the inhibition of NAMPT. Our results show that in -7/-7q AML, differentiated CD34+CD38+ progenitor cells are the most sensitive to the inhibition of NAMPT. In addition, we found that the combination of BCL2 inhibitor venetoclax and a NAMPT inhibitor efficiently eradicated undifferentiated AML blasts with -7/-7q. In conclusion, our findings demonstrate that AML samples with -7/-7q are highly sensitive to NAMPT inhibition, suggesting that NAMPT inhibitors have the potential to be an effective targeted therapy for patients with monosomy 7 or del(7q).KEY POINTSMonosomy 7 and del(7q) result in a one-copy deletion of the NAMPT gene at 7q22.1NAMPT haploinsufficiency causes a vulnerability to the inhibition of NAMPT

MPFC gating strategy

Purpose: Leukemic stem cells (LSCs) may harbor important resistance to tyrosine kinase inhibitors in chronic myelogenous leukemia (CML). We identified Philadelphia chromosome (Ph)–positive CD34+CD38− bone marrow cells (here denoted LSCs) and addressed their response-predictive value in patients with CML (n = 48) subjected to nilotinib in the ENEST1st trial (NCT01061177).Experimental design: Two flow cytometry–based cell sorting methods were used with multiparameter-directed CD45- (MPFC) and BCR-ABL1 probe-linked (FISH) identification of Ph-positive cells, respectively.Results: We observed a positive correlation between the proportion of LSCs at diagnosis and established prognostic markers (blast count, spleen size, Sokal score, and hemoglobin). Conversely, a high LSC burden predicted for an inferior molecular response at 3 (MPFC and FISH), 6 (MPFC), 9 (FISH), and 15 months (FISH). During nilotinib therapy, the proportion of LSCs decreased rapidly. At 3 months, a median of only 0.3% LSCs remained among CD34+CD38− cells, and in 33% of the patients the LSC clone was not detectable anymore (FISH). The response kinetics was similar in LSC fractions as it was in the progenitor and unseparated bone marrow cell fractions.Conclusions: The proportion of LSCs at diagnosis, as analyzed by two independent methodologies, reflects the biology of the disease and appeared as a prognostic and response-predictive marker in patients with CML subjected to first-line nilotinib therapy. Clin Cancer Res; 22(16); 4030–8. ©2016 AACR.

Consort diagram

LSC analysis at 3 months time point by FISH

PDF file - 546K, In vitro characterization of NTR/CytoCy5S.

PDF file - 99K, Materials and methods of CytoCy5S synthesis, purification, spectral and structural characterization in addition to NTR/CytoCy5S enzymatic reaction conditions and western blots.

The ability to visualize reporter gene expression in vivo has revolutionized all facets of biologic investigation and none more so than imaging applications in oncology. Near-infrared reporter gene imaging may facilitate more accurate evaluation of chemotherapeutic response in preclinical models of orthotopic and metastatic cancers. We report the development of a cell permeable, quenched squarine probe (CytoCy5S), which is reduced by Escherichia coli nitroreductase (NTR), resulting in a near-infrared fluorescent product. Time-domain molecular imaging of NTR/CytoCy5S reporter platform permitted noninvasive monitoring of disease progression in orthotopic xenografts of disseminated leukemia, lung, and metastatic breast cancer. This methodology facilitated therapeutic evaluation of NTR gene–directed enzymatic prodrug therapy with conventional metronidazole antibiotics. These studies show NTR/CytoCy5S as a near-infrared gene reporter system with broad preclinical and prospective clinical applications within imaging, and gene therapy, of cancer. Cancer Res; 73(4); 1276–86. ©2012 AACR.

PDF file - 358K, In vitro viability of NB4, NCI-H460 and MDA-MB-231 cells � NTR � CytoCy5S.

PDF file - 99K

PDF file - 402K, Synthesis, mechanism and spectral characteristics of CytoCy5S.

PDF file - 314K, In vivo characterization of NTR/CytoCy5S fluorescence and fluorescence lifetime distributions in NB4NTR+GFP+ subcutaneous tumors, NCI-H460NTR+Luc+GFP+ orthotopic xenografts and gastrointestinal tract.

PDF file - 718K, In vitro viability of NB4 and MDA-MB-231 cells � NTR � MTZ.

PDF file - 1949K, Flow cytometry quantification of NTR/CytoCy5S fluorescence in NB4 cells � NTR � CytoCy5S.

Metastatic castration-resistant prostate cancer (mCRPC) is an immunologically cold disease with dismal outcomes. Cryoablation destroys cancer tissue, releases tumor-associated antigens and creates a pro-inflammatory microenvironment, while dendritic cells (DCs) activate immune responses through processing of antigens. Immunotherapy combinations could enhance the anti-tumor efficacy. This open-label, single-arm, single-center phase I trial determined the safety and tolerability of combining cryoablation and autologous immature DC, without and with checkpoint inhibitors. Immune responses and clinical outcomes were evaluated. Patients with mCRPC, confirmed metastases and intact prostate gland were included. The first participants underwent prostate cryoablation with intratumoral injection of autologous DCs in a 3 + 3 design. In the second part, patients received cryoablation, the highest acceptable DC dose, and checkpoint inhibition with either ipilimumab or pembrolizumab. Sequentially collected information on adverse events, quality of life, blood values and images were analyzed by standard descriptive statistics. Neither dose-limiting toxicities nor adverse events > grade 3 were observed in the 18 participants. Results indicate antitumor activity through altered T cell receptor repertoires, and 33% durable (> 46 weeks) clinical benefit with median 40.7 months overall survival. Post-treatment pain and fatigue were associated with circulating tumor cell (CTC) presence at inclusion, while CTC responses correlated with clinical outcomes. This trial demonstrates that cryoimmunotherapy in mCRPC is safe and well tolerated, also for the highest DC dose (2.0 × 108) combined with checkpoint inhibitors. Further studies focusing on the biologic indications of antitumor activity and immune system activation could be considered through a phase II trial focusing on treatment responses and immunologic biomarkers.

Bone regeneration from mesenchymal stromal cells (MSC) is attributed to comprehensive immune modulation mediated by the MSC. However, the temporal and spatial regulation of these immune responses has not yet been described. The aim of the present study was to assess the local and systemic innate immune responses to implantation of biphasic calcium phosphate biomaterial (BCP) alone, or with bone marrow derived MSC (BCP+MSC), in critical-sized calvarial bone defects of Lewis rats. Four weeks after implantation, flow cytometry analysis of innate immune cells revealed increased numbers of circulating classical monocyte-macrophages (MM) and decreased non-classical MM in the BCP+MSC group. At week 8, this differential systemic MM response was associated with an increased presence of local tissue anti-inflammatory macrophages expressing CD68 and CD163 markers (M2-like). In the BCP group without MSC, NK cells increased at weeks 1 and 4, and neutrophils increased in circulation at weeks 2 and 8. At week 8, the increase in number of neutrophils in circulation was associated with decreased local tissue neutrophils, in the BCP+MSC group. Gene expression analysis of tissue biopsies from defects implanted with BCP+MSC, in comparison to BCP alone, revealed upregulated expression of early osteogenesis genes along with macrophage differentiation-related genes at weeks 1 and 8 and neutrophil chemotaxis-related genes at week 1. This study is the first to demonstrate that surgical implantation of BCP or BCP+MSC grafts differentially regulate both systemic and local tissue innate immune responses which enhance bone formation. The results provide new insights into immune mechanisms underlying MSC-mediated bone regeneration. STATEMENT OF SIGNIFICANCE: The suitability of biphasic calcium phosphate and mesenchymal stromal cell construct (BCP+MSC) transplantation is evident from their progress in clinical trials for treating challenging maxillofacial bone defects. But less is known about the overall immune response generated by this surgical process and how it later impacts the bone formation. To this end, it is crucial to understand for both clinicians and researchers, the systemic immune response to transplanting MSC in patients for ensuring both the safety and efficacy of cell therapies. In this study, we used rat calvarial bone defect model and showed that both systemic and local innate immunes responses (monocyte-macrophages and neutrophils) are favorably directed towards enhanced bone formation in BCP+MSC implanted defects, as compared to BCP alone.

Recurrent somatic internal tandem duplications (ITD) in the FMS‐like tyrosine kinase 3 (FLT3) gene characterise approximately one third of patients with acute myeloid leukaemia (AML), and FLT3‐ITD mutation status guides risk‐adapted treatment strategies. The aim of this work was to characterise FLT3‐ITD variant distribution in relation to molecular and clinical features, and overall survival in adult AML patients. We performed two parallel retrospective cohort studies investigating FLT3‐ITD length and expression by cDNA fragment analysis, followed by Sanger sequencing in a subset of samples. In the two cohorts, a total of 139 and 172 mutant alleles were identified in 111 and 123 patients, respectively, with 22% and 28% of patients presenting with more than one mutated allele. Further, 15% and 32% of samples had a FLT3‐ITD total variant allele frequency (VAF), Internal tandem duplications (ITD) in the FMS‐like tyrosine kinase 3 (FLT3) gene is present in 20–30% of acute myeloid leukaemia (AML) patients. Here, we perform molecular profiling of FLT3‐ITD mutations in 263 AML patients. We provide a comprehensive overview of the heterogeneity and impact of FLT3‐ITD mutations by assessing various molecular features and the relationship with clinical features and overall survival.

The use of single-cell profiling of phenotypes is suggested to inform about chemoresistance and lack of treatment response in cancer. Mass cytometry by time-of-flight (CyTOF) allows high throughput multiparametric analysis at the single-cell level to perform for in-depth characterisation of heterogeneity in leukemia. However, computational identification of cell populations from CyTOF, and utilisation of single-cell data for biomarker discoveries is challenging. Here, we deployed a machine learning-based framework that enables automatic cell population annotation, and systematic exploration of interactions between signalling proteins in a CyTOF antibody panel. We applied the developed framework to analyse a cohort of 45 leukemia patients. We investigated associations between the cellular composition and clinicopathological and genetic features, and reported salient signalling interactions of Multipotent Progenitor-like leukemia cells that were sufficient to predict short-term survival at time of diagnosis. Our findings confirmed that targeting cell type-specific signalling interactions in leukemia might improve existing patient stratification methods with the potential to inform early about more precise treatment options.

Incidence, molecular presentation and outcome of acute myeloid leukaemia (AML) are influenced by sex, but little attention has been directed at untangling sex‐related molecular and phenotypic differences between female and male patients. While increased incidence and poor risk are generally associated with a male phenotype, the poor prognostic FLT3 internal tandem duplication (FLT3‐ITD) mutation and co‐mutations with NPM1 and DNMT3A are overrepresented in female AML. Here, we have investigated the relationship between sex and FLT3‐ITD mutation status by comparing clinical data, mutational profiles, gene expression and ex vivo drug sensitivity in four cohorts: Beat AML, LAML‐TCGA and two independent HOVON/SAKK cohorts, comprising 1755 AML patients in total. We found prevalent sex‐associated molecular differences. Co‐occurrence of FLT3‐ITD, NPM1 and DNMT3A mutations was overrepresented in females, while males with FLT3‐ITDs were characterized by additional mutations in RNA splicing and epigenetic modifier genes. We observed diverging expression of multiple leukaemia‐associated genes as well as discrepant ex vivo drug responses, suggestive of discrete functional properties. Importantly, significant prognostication was observed only in female FLT3‐ITD‐mutated AML. Thus, we suggest optimization of FLT3‐ITD mutation status as a clinical tool in a sex‐adjusted manner and hypothesize that prognostication, prediction and development of therapeutic strategies in AML could be improved by including sex‐specific considerations., Internal tandem duplications (ITDs) in the FMS‐like tyrosine kinase 3 (FLT3) gene are linked to poor prognosis in acute myeloid leukaemia (AML). Here, we investigated sex‐related differences in mutation, gene expression and drug sensitivity profiles in FLT3‐ITD‐mutated AML. We demonstrated significant sex‐associated molecular and functional differences, and surprisingly identified significant prognostication related to FLT3‐ITD only in female AML patients.

Objectives: This study aims to retrospectively assess C-lectin-like molecule 1 (CLL-1) bimodal expression on CD34+ blasts in acute myeloid leukemia (AML) patients (total N = 306) and explore potential CLL-1 bimodal associations with leukemia and patient-specific characteristics. Methods: Flow cytometry assays were performed to assess the deeper immunophenotyping of CLL-1 bimodality. Cytogenetic analysis was performed to characterize the gene mutation on CLL-1-negative subpopulation of CLL-1 bimodal AML samples. Results: The frequency of a bimodal pattern of CLL-1 expression of CD34+ blasts ranged from 8% to 65% in the different cohorts. Bimodal CLL-1 expression was most prevalent in patients with MDS-related AML (P = .011), ELN adverse risk (P = .002), NPM1 wild type (WT, P = .049), FLT3 WT (P = .035), and relatively low percentages of leukemia-associated immunophenotypes (P = .006). Additional immunophenotyping analysis revealed the CLL-1- subpopulation may consist of pre-B cells, immature myeloblasts, and hematopoietic stem cells. Furthermore, (pre)-leukemic mutations were detected in both CLL-1+ and CLL-1- subfractions of bimodal samples (N = 3). Conclusions: C-lectin-like molecule 1 bimodality occurs in about 25% of AML patients and the CLL-1- cell population still contains malignant cells, hence it may potentially limit the effectiveness of CLL-1-targeted therapies and warrant further investigation. Keywords: CD34+ blasts; CLL-1; acute myeloid leukemia; bimodality; bone marrow aspirates; flow cytometry.

Background Matching treatment based on tumour molecular characteristics has revolutionized the treatment of some cancers and has given hope to many patients. Although personalized cancer care is an old concept, renewed attention has arisen due to recent advancements in cancer diagnostics including access to high-throughput sequencing of tumour tissue. Targeted therapies interfering with cancer specific pathways have been developed and approved for subgroups of patients. These drugs might just as well be efficient in other diagnostic subgroups, not investigated in pharma-led clinical studies, but their potential use on new indications is never explored due to limited number of patients. Methods In this national, investigator-initiated, prospective, open-label, non-randomized combined basket- and umbrella-trial, patients are enrolled in multiple parallel cohorts. Each cohort is defined by the patient’s tumour type, molecular profile of the tumour, and study drug. Treatment outcome in each cohort is monitored by using a Simon two-stage-like ‘admissible’ monitoring plan to identify evidence of clinical activity. All drugs available in IMPRESS-Norway have regulatory approval and are funded by pharmaceutical companies. Molecular diagnostics are funded by the public health care system. Discussion Precision oncology means to stratify treatment based on specific patient characteristics and the molecular profile of the tumor. Use of targeted drugs is currently restricted to specific biomarker-defined subgroups of patients according to their market authorization. However, other cancer patients might also benefit of treatment with these drugs if the same biomarker is present. The emerging technologies in molecular diagnostics are now being implemented in Norway and it is publicly reimbursed, thus more cancer patients will have a more comprehensive genomic profiling of their tumour. Patients with actionable genomic alterations in their tumour may have the possibility to try precision cancer drugs through IMPRESS-Norway, if standard treatment is no longer an option, and the drugs are available in the study. This might benefit some patients. In addition, it is a good example of a public–private collaboration to establish a national infrastructure for precision oncology. Trial registrations EudraCT: 2020-004414-35, registered 02/19/2021; ClinicalTrial.gov: NCT04817956, registered 03/26/2021.

Aberrant pro-survival signaling is a hallmark of cancer cells, but the response to chemotherapy is poorly understood. In this study, we investigate the initial signaling response to standard induction chemotherapy in a cohort of 32 acute myeloid leukemia (AML) patients, using 36-dimensional mass cytometry. Through supervised and unsupervised machine learning approaches, we find that reduction of extracellular-signal-regulated kinase (ERK) 1/2 and p38 mitogen-activated protein kinase (MAPK) phosphorylation in the myeloid cell compartment 24 h post-chemotherapy is a significant predictor of patient 5-year overall survival in this cohort. Validation by RNA sequencing shows induction of MAPK target gene expression in patients with high phospho-ERK1/2 24 h post-chemotherapy, while proteomics confirm an increase of the p38 prime target MAPK activated protein kinase 2 (MAPKAPK2). In this study, we demonstrate that mass cytometry can be a valuable tool for early response evaluation in AML and elucidate the potential of functional signaling analyses in precision oncology diagnostics.

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We generated ex vivo drug-response and multiomics profiling data for a prospective series of 252 samples from 186 patients with acute myeloid leukemia (AML). A functional precision medicine tumor board (FPMTB) integrated clinical, molecular, and functional data for application in clinical treatment decisions. Actionable drugs were found for 97% of patients with AML, and the recommendations were clinically implemented in 37 relapsed or refractory patients. We report a 59% objective response rate for the individually tailored therapies, including 13 complete responses, as well as bridging five patients with AML to allogeneic hematopoietic stem cell transplantation. Data integration across all cases enabled the identification of drug response biomarkers, such as the association of IL15 overexpression with resistance to FLT3 inhibitors. Integration of molecular profiling and large-scale drug response data across many patients will enable continuous improvement of the FPMTB recommendations, providing a paradigm for individualized implementation of functional precision cancer medicine. Significance: Oncogenomics data can guide clinical treatment decisions, but often such data are neither actionable nor predictive. Functional ex vivo drug testing contributes significant additional, clinically actionable therapeutic insights for individual patients with AML. Such data can be generated in four days, enabling rapid translation through FPMTB. See related commentary by Letai, p. 290. This article is highlighted in the In This Issue feature, p. 275

Pan-RAF inhibitors have shown promise as antitumor agents in RAS and RAF mutated solid cancers. However, the efficacy of pan-RAF inhibitors in acute myeloid leukemia (AML) has not previously been explored. In AML, the RAS–RAF–MEK–ERK (MAPK) pathway is one of the most aberrantly activated oncogenic pathways, but previous targeting of this pathway by MEK inhibitors has not proven effective in clinical trials. Here we show that pan-RAF inhibition, but not MEK inhibition, induced cell death in 29% of AML samples while being nontoxic toward healthy bone marrow cells. Mechanistically, pan-RAF inhibition downregulated MCL1 protein synthesis and induced apoptosis in cells dependent on MCL1 for their survival. Furthermore, the combination of a pan-RAF and a BCL2 inhibitor overcame resistance to either compound alone in AML cell lines, as well as synergized and induced long-term responses ex vivo in AML patient samples relapsed or refractory to azacitidine + venetoclax treatment. Together, our results indicate that pan-RAF inhibition, alone or in combination with BCL2 inhibition, is a promising treatment strategy for AML.

A previously designed and developed 12-step total synthesis that includes [1,1'-biphenyl]-2-amine and carbazole intermediates and that ultimately produces the carbazole alkaloid carbazomycin G was exploited as a screening compound library with the goal of identifying potential lead compound(s) with cytotoxic effect. These compounds were investigated by using in-vitro tests involving the two human cell lines HL-60 and MOLM-13, which both model acute myeloid leukaemia (AML). The in-vitro biological test results were used together with the molecular structures of the various intermediates in a concise SAR analysis. Several of the intermediates revealed cytotoxicity (IC50

Bevacizumab is included in an increasing number of clinical trials. To find biomarkers to predict and monitor treatment response, cancer and angiogenesis relevant mutations in tumour and circulating tumour DNA (ctDNA) were investigated in 26 metastatic melanoma patients treated with bevacizumab. Patients with >1% BRAF/NRAS ctDNA at treatment start had significantly decreased progression free survival (PFS) and overall survival (OS) (PFS: p = 0.019, median 54 vs 774 days, OS: p = 0.026, median 209 vs 1064 days). Patients with >1% BRAF/NRAS ctDNA during treatment showed similar results (PFS: p = 0.002, OS: p = 0.003). ≤1% BRAF/NRAS ctDNA and normal lactate dehydrogenase (LDH) levels both significantly predicted increased response to treatment, but BRAF/NRAS ctDNA was better at predicting response compared to LDH at treatment start (OR 16.94, p = 0.032 vs OR 4.57, p = 0.190), and at predicting PFS (HR 6.76, p = 0.002) and OS (HR 6.78, p = 0.002) during therapy. ctDNA BRAF p.V600D/E/K and NRAS p.G12V/p.Q61K/L/R were better biomarkers for response prediction than TERT promoter mutations (OR 1.50, p = 0.657). Next generation sequencing showed that all patients with ≥2 mutations in angiogenesis-relevant genes had progressive disease, but did not reveal other biomarkers identifying responders. To conclude, ctDNA and LDH are useful biomarkers for both monitoring and predicting response to bevacizumab.

Objectives Treatment-free remission (TFR) has emerged as a treatment goal in chronic myeloid leukemia in the chronic phase (CML-CP). Attempts to increase proportion of patients achieving TFR include combination of tyrosine kinase inhibitors (TKI) and other drugs. Interferon-α in addition to TKI has shown promising efficacy but with dose-dependent toxicity and discontinuations. NordCML007 was initiated to study the efficacy and safety of low dose pegylated IFN-α (PegIFN-α) in combination with dasatinib (DAS) in CML-CP. Methods Forty patients with newly diagnosed CML-CP were given DAS upfront. After month 3 (M3) 15 μg/wk of PegIFN-α was added and increased to 25 μg/wk from M7 until M15. DAS treatment was continued and adverse events and BCR-ABL1 qRT-PCR values were reported yearly after M24. Results from M1 to M18 have previously been published, and here we present long-term data. Results After 5 years of follow-up, there were no suspected unexpected serious adverse reactions, no increase in serosal effusions, no disease progressions and no CML-related deaths. Rates of MR3.0 (MMR), MR4.0 and MR4.5 were 84.6%, 64.1% and 51.3% respectively at M60, and 95% of patients reached MMR at some point during the study. Conclusion Initial addition of PegIFN-α to DAS shows good long-term efficacy without increased toxicity. Title in Web of Science: Long-term tolerability and efficacy after initial PegIFN-alpha addition to dasatinib in CML-CP: Five-year follow-up of the NordCML007 study

Background. Persistence of measurable residual disease (MRD) is a poor prognostic factor and predicts relapse in acute myeloid leukemia (AML). In a phase I study, the allogeneic leukemia-derived dendritic cell vaccine, DCP-001, has shown safety and humoral and cellular immune responses (A.A. van de Loosdrecht, et al. Cancer Immunol. Immunother. 2018;67:1505). In the current phase II study, (Clintrials.gov: NCT03697707) we report on progress and evaluation of MRD conversion, as primary endpoint, relapse free and overall survival. Methods. AML-patients, ineligible at screening for HSCT, who are in first complete remission (CR1) but with MRD receive 4 biweekly doses of 25e6 or 50e6 cells per vaccination (cells/vc) followed by 2 doses of 10e6 cells/vc as boosts at week 14 and 18. MRD is assessed at 4 timepoints (baseline, week 14, 20 and 32) by flow cytometry and/or molecular analyses. Primary endpoints are the effect of vaccination on MRD status and safety and tolerability of the two vaccination schedules. Secondary endpoints include relapse free, overall survival and immunological response evaluation. Results. As of 28 th July 2021, 19 patients have been enrolled, of which 10 patients have been given at least 4 vaccinations with 25e6 cells/vc and 9 with 50e6 cells/vc. No serious adverse events (AE) or severe AE (grade 3 or higher) related to DCP-001 have been reported. AE's related to DCP-001 are mainly injection site reactions, occurring within 48 hours after intradermal administration. In the 25e6 cells/vc cohort all patients have completed the treatment phase up to week 32, allowing full assessment of MRD response. Three patients have converted to MRD negative, 4 patients relapsed (followed by HSCT for 1 patient), 3 patients remained MRD positive, of which 2 patients underwent HSCT immediately after completion of the full dosing schedule. In this cohort 2 patients eventually died during follow up. Treatment is still ongoing in the 50e6 dose cohort, with thus far one additional MRD conversion reported and two relapses, 3 patients with stable MRD levels, and 3 have no MRD data available yet. Median follow-up of patients in the 25e6 cells/vc cohort was 288 days (range 148 - 546). Median RFS and OS have not yet been reached, but estimated RFS and OS at 12 months is calculated at 57% and 79%, respectively (Figure 1). MRD converted patients after DCP-001 vaccination, showed improved survival, compared to patients without MRD conversion (Figure 2). All 4 patients who converted to MRD negative are still in CR and alive (FU median 423.5 days (range 140 - 546). Immunological monitoring of patients is currently being performed. As previously reported (abstract #168, ASH2020), 3 of 4 evaluable patients show at least 1 or more responses against tumor-associated antigens known to be present in DCP-001 in IFNy ELISPOT assay. Conclusion/discussion. Four patients have shown MRD conversion (3 in the 25e6 dose cohort, and 1 in the 50e6 dose cohort). Six patients remained in complete remission with stable or declining levels of MRD, 6 patients relapsed and for 3 patients no MRD data is available yet. Median RFS and OS have not yet been reached. MRD conversion showed improved relapse free and overall survival. Treatment with DCP-001 is very well tolerated, with limited side effects mainly related to intradermal administration. Immunological analyses for specific tumor-associated antigen responses and general immune profiling are currently being performed. Preliminary data from this study shows that the relapse vaccine DCP-001 is a promising treatment for patients with AML in complete remission but with residual disease aiming to deepen responses and prolong survival. Its excellent safety profile allows for future combination therapy. Figure 1 Figure 1. Disclosures Van de Loosdrecht: Novartis: Consultancy; Alexion: Consultancy; Roche: Consultancy; Amgen: Consultancy; Celgene: Consultancy, Research Funding. Cloos: Takeda: Research Funding; Novartis: Consultancy, Other, Research Funding; Navigate: Patents & Royalties; Merus: Other, Research Funding; Janssen: Research Funding; Helsinn: Other; Genentech: Research Funding; DC-One: Other, Research Funding; Astellas: Speakers Bureau. Platzbecker: AbbVie: Honoraria; Janssen: Honoraria; Novartis: Honoraria; Celgene/BMS: Honoraria; Geron: Honoraria; Takeda: Honoraria. Holderried: Gilead Sciences: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Amgen: Speakers Bureau; MSD: Speakers Bureau; GSK: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees; Sanofi: Consultancy, Membership on an entity's Board of Directors or advisory committees; Jazz Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees; Therakos: Other: Travel support; Abbvie: Other: Travel support; Medac: Other: Travel support; Eurocept Pharmaceuticals: Other: Travel support; Janssen: Other: Travel support; Daiichi Sankyo: Other: travel support. Giagounidis: Novartis: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees. van Zeeburg: Immunicum AB: Current Employment; Kiadis: Ended employment in the past 24 months. Rovers: Immunicum AB: Current Employment. Gjertsen: KinN Therapeutics: Current holder of stock options in a privately-held company; Alden Cancer Therapy: Current holder of stock options in a privately-held company; Pfizer Inc.: Consultancy; BerGenBio: Consultancy; Novartis: Consultancy.

Treatment of acute myeloid leukaemia (AML) relies on decades-old drugs, and while recent years have seen some breakthroughs, AML is still characterised by poor prognosis and survival rate. Drug repurposing can expedite the preclinical development of new therapies, and by nanocarrier encapsulation, the number of potentially viable drug candidates can be further expanded. The anti-psychotic drug chlorpromazine (CPZ) has been identified as a candidate for repurposing for AML therapy. Nanoencapsulation may improve the suitability of CPZ for the treatment of AML by reducing its effect on the central nervous system. Using the emulsion-evaporation technique, we have developed PEGylated PLGA nanoparticles loaded with CPZ for AML therapy. The nanoparticles were characterised to be between 150 and 300 nm by DLS, of spherical morphology by TEM, with a drug loading of at least 6.0% (w/w). After an initial burst release of adsorbed drug, the remaining 80% of the drug was retained in the PLGA nanoparticles for at least 24 h. The CPZ-loaded nanoparticles had equal cytotoxic potential towards AML cells to free CPZ, but acted more slowly, in line with the protracted drug release. Crucially, nanoparticles injected intravenously into zebrafish larvae did not accumulate in the brain, and nanoencapsulation also prevented CPZ from crossing an artificial membrane model. This demonstrates that the purpose for nanoencapsulation of CPZ is fulfilled, namely avoiding effects on the central nervous system while retaining the anti-AML activity of the drug. publishedVersion

We describe here a simple and efficient antibody titration approach for cell‐surface markers and intracellular cell signaling targets for mass cytometry. The iterative approach builds upon a well‐characterized backbone panel of antibodies and analysis using bioinformatic tools such as SPADE. Healthy peripheral blood and bone marrow cells are stained with a pre‐optimized “backbone” antibody panel in addition to the progressively diluted (titrated) antibodies. Clustering based on the backbone panel enables the titration of each antibody against a rich hematopoietic background and assures that nonspecific binding and signal spillover can be quantified accurately. Using a slightly expanded backbone panel, antibodies quantifying changes in transcription factors and phosphorylated antigens are titrated on ex vivo stimulated cells to optimize sensitivity and evaluate baseline expression. Based on this information, complex panels of antibodies can be thoroughly optimized for use on healthy whole blood and bone marrow and are easily adaptable to the investigation of samples from for example clinical studies. © 2019 The Authors. Cytometry Part A published by Wiley Periodicals, Inc. on behalf of International Society for Advancement of Cytometry.