Oral eltanexor treatment of patients with higher-risk myelodysplastic syndrome refractory to hypomethylating agents

Patients with higher-risk myelodysplastic syndromes (MDS) refractory to hypomethylating agents (HMAs) have limited therapeutic options and an expected overall survival (OS) of 3–5 months. Eltanexor is an investigational oral selective inhibitor of nuclear export with low central nervous system penetrance and an acceptable tolerability profile. Preclinical studies suggest that myeloid malignancies are sensitive to nuclear export inhibition. Eltanexor exhibited efficacy in hematologic models, supporting exploration in a clinical trial. This phase 1/2 study (NCT02649790) assessed single-agent activity of eltanexor in patients with higher-risk MDS and 5–19% myeloblasts. Two starting doses of eltanexor were evaluated: 20 mg (n = 15), 10 mg (n = 5), both administered on days 1–5 each week of a 28-day cycle. Twenty patients with primary HMA-refractory MDS, with a median age of 77 years (range 62–89), and a median of two prior treatment regimens (range 1–4) were enrolled. Of these, 15 were evaluated for efficacy and 20 for safety. The overall response rate (ORR) was 53.3%, with seven patients (46.7%) achieving marrow complete remission (mCR) and one additional patient achieving hematologic improvement (HI). In the 10 mg group, three patients (60%) reached mCR and two (40%) stable disease (SD), while for 20 mg, four patients (40%) had mCR and two (20%) SD. A total of three patients (20%) had HI and became transfusion independent ≥ 8 weeks. Median OS for the efficacy-evaluable patients (n = 15) was 9.86 months (7.98, NE). Overall, the most frequently reported treatment-related adverse events were nausea (45%), diarrhea (35%), decreased appetite (35%), fatigue and neutropenia (both 30%). Single-agent oral eltanexor was active, safe, and well tolerated in patients with higher-risk, primary HMA-refractory MDS.

Effect of Prior Therapy and Disease Refractoriness on the Efficacy and Safety of Oral Selinexor in Patients with Diffuse Large B-cell Lymphoma (DLBCL): A Post-hoc Analysis of the SADAL Study

BACKGROUND

Despite a number of treatment options, patients with diffuse large B-cell lymphoma (DLBCL) whose disease has become refractory to treatment have a poor prognosis. Selinexor is a novel, oral drug that is approved to treat patients with relapsed/refractory DLBCL. In this post hoc analysis of the SADAL study, a multinational, open-label study, we evaluated subpopulations to determine if response to single agent selinexor is impacted by number of lines of prior treatment, autologous stem cell transplant (ASCT), response to first and most recent therapies, and time to progressive disease.

PATIENTS

Patients (n = 134) with DLBCL after 2-5 prior therapies were enrolled in SADAL and received 60mg selinexor twice weekly.

RESULTS

The median overall survival was 9.0 months and median progression free survival was 2.6 months. Patients who had the best overall response rate (ORR) and disease control rate were those who had prior ASCT (42.5% and 50.0%) or responded to last line of therapy (35.9% and 43.5%). Patients with primary refractory DLBCL also showed responses (ORR 21.8%). Adverse events between subgroups were similar to the overall study population, the most common being thrombocytopenia (29.1%), fatigue (7.5%), and nausea (6.0%).

CONCLUSION

Regardless of prior therapy and disease refractory status, selinexor treatment demonstrated results consistent with its novel mechanism of action and lack of cross-resistance. Thus, single agent oral selinexor can induce deep, durable, and tolerable responses in patients with DLBCL who have recurrent disease after several chemoimmunotherapy combination regimens.

A phase 1, open-label, dose-escalation study of selinexor plus ruxolitinib in patients with treatment-naïve myelofibrosis

7060

Background: Myelofibrosis (MF) is a myeloproliferative neoplasm characterized by unregulated, clonal proliferation of a hematopoietic stem cells in the bone marrow and is commonly associated with gene mutations in JAK2, CALR, or MPL. Front-line therapy may include the JAK1/2 inhibitor ruxolitinib (RUX), resulting in spleen volume reductions and improvement in MF-related symptoms. Despite the therapeutic effect of RUX, most patients (pts) eventually progress and thus novel combinations are required to increase responses and delay progression. Selinexor (SEL) is an oral selective inhibitor of nuclear export (SINE) compound, specifically inhibiting exportin-1 (XPO1), and currently approved for treatment of multiple myeloma and diffuse large B-cell lymphoma. Significant activity of SEL in combination with RUX has been shown in preclinical studies, and SEL monotherapy in MF refractory to JAK inhibitors demonstrated robust clinical activity and a tolerable safety profile (NCT03627403). Here, we present the initial results of a phase 1 dose escalation study of the combination SEL and RUX in treatment-naïve MF. Methods: The ongoing multicenter, open-label, Phase 1/2 study (NCT04562389) is evaluating the efficacy and safety of SEL plus RUX in JAKi-naïve MF pts. Two dose levels of SEL were evaluated, 40mg and 60mg once-weekly (QW) plus RUX twice daily (BID) as per label in 28-day cycles, using a 3+3 design. All pts received 5-HT3 antagonist for nausea prophylaxis. Primary objectives include safety, maximum tolerated dose (MTD), recommended Phase 2 dose (RP2D), and preliminary efficacy. Secondary objectives include spleen, symptom, and anemia response, and OS. Results: As of 31 Jan 2022, 10 pts have been dosed in 2 dose levels (40mg (n = 3), and 60mg (n = 7) SEL QW plus RUX). RUX starting dose was 20 mg in 8 pts, 15 mg in one patient and 10 mg in one patient. The median age was 64 (range 45-76). Seven pts had primary MF and 3 had post-ET MF. DIPSS risk category was int-1 (n = 4), int-2 (n = 4) and high risk (n = 2). No dose limiting toxicities have been reported at either dose levels of SEL. One patient required dose interruption due to dizziness and later discontinued treatment due to new onset of atrial fibrillation and pulmonary hypertension (unrelated to SEL and RUX) after 5 months of therapy. All other pts remain on study. There was no grade 3 neutropenia or thrombocytopenia observed. Hemoglobin level was maintained without any significant worsening. The most common treatment-emergent adverse event was low grade nausea (30%). All pts experienced improvement in their white blood cell count. Four of the first 5 evaluable pts demonstrated ≥35% spleen volume reduction at week 12. Conclusions: The combination of SEL and RUX has been well-tolerated and with a manageable side effect profile. No dose limiting toxicities were observed in pts with treatment-naïve MF in cohort 1 of once weekly oral SEL 40 and 60 mg with RUX. Clinical trial information: NCT04562389.

Comparison of the Effectiveness and Safety of the Oral Selective Inhibitor of Nuclear Export, Selinexor, in Diffuse Large B Cell Lymphoma Subtypes

BACKGROUND

The SADAL study evaluated oral selinexor in patients with relapsed and/or refractory diffuse large B-cell lymphoma (DLBCL) after at least 2 prior lines of systemic therapy. In this post-hoc analysis, we analyzed the outcomes of the SADAL study by DLBCL subtype to determine the effects of DLBCL subtypes on efficacy and tolerability of selinexor.

PATIENTS AND METHODS

Data from 134 patients in SADAL were analyzed by DLBCL subtypes for overall response rate (ORR), overall survival (OS), duration of treatment response, progression-free survival, and adverse events rate.

RESULTS

ORR in the entire cohort was 29.1%, and similar in patients with germinal center (GCB) versus non-GCB DLBCL (31.7% vs. 24.2%, P = 0.45); transformed DLBCL showed a trend towards higher ORR than de novo DLBCL: 38.7% vs. 26.2% (P = 0.23). Despite similar prior treatment regimens and baseline characteristics, patients with DLBCL and normal C-MYC/BCL-2 protein expression levels had a significantly higher ORR (46.2% vs.14.8%, P = 0.012) and significantly longer OS (medians 13.7 vs. 5.1 months, hazard ratio 0.43 [95% CI, 0.23-0.77], P = 0.004) as compared with those whose DLBCL had C-MYC and BCL-2 overexpression. Among patients who had normal expression levels of either C-MYC or BCL-2 and baseline hemoglobin levels ≥ 10g/dL, ORR was 51.5% (n = 47), with median OS of 15.5 months and median PFS of 4.6 months. Similar rates of adverse events were noted in all subgroups.

CONCLUSIONS

Overall, single agent oral selinexor showed strong responses in patients with limited treatment alternatives regardless of germinal center B-cell type or disease origin.

Survival among patients with relapsed/refractory diffuse large B cell lymphoma treated with single-agent selinexor in the SADAL study

Patients with RR DLBCL who have received ≥ 2 lines of therapy have limited treatment options and an expected overall survival (OS) of < 6 months. The SADAL study evaluated single-agent oral selinexor in patients with RR DLBCL and demonstrated an overall response rate (ORR) of 29.1% with median duration of response (DOR) of 9.3 months. The analyses described here evaluated a number of subpopulations in order to understand how response correlates with survival outcomes in order to identify patients who could most optimally benefit from selinexor treatment. Median age was 67 years; 44.8% of patients were ≥ 70 years of age. The median OS was 9.0 months (95% CI 6.2, 13.7) at a median follow-up of 14.8 months. The median OS was not reached in patients with a CR or PR, while patients who did not respond have a median OS of 4.9 months (p < 0.0001). Patients < 70 years had an OS of 11.1 months compared with 7.8 months in patients ≥ 70 years. Among patients with or without prior ASCT, the median OS was 10.9 and 7.8 months, respectively. Among patients with disease refractory to the most recent DLBCL treatment regimen, the median OS was 7.0 months compared with 11.1 months for disease not refractory to the most recent treatment. In a patient population in which survival is expected to be < 6 months, treatment with single-agent oral selinexor was associated with a median survival of 9 months. Increased median OS observed in patients responding to selinexor was consistent across subgroups regardless of age, prior ASCT therapy, or refractory status. Randomized studies of selinexor in combination with a variety of other anti-DLBCL agents are planned. This trial was registered at ClinicalTrials.gov (NCT02227251) on August 28, 2014. https://clinicaltrials.gov/ct2/show/NCT02227251 .

Updated overall survival of eltanexor for the treatment of patients with hypomethylating agent refractory myelodysplastic syndrome

e19037

Background: Patients (pts) with myelodysplastic syndrome (MDS) refractory to hypomethylating agents (HMAs) have limited therapeutic options and a dismal prognosis with a median overall survival (mOS) of 4-6 months. Eltanexor (ELTA) is a second-generation, oral, selective inhibitor of nuclear export (SINE) compound that showed anti-tumor activity and lower brain penetration compared to selinexor (SEL) in nonclinical models. It was hypothesized that ELTA could be dosed more frequently than SEL with a lower incidence of centrally mediated nausea. Early results from a phase 1/2 study of ELTA in pts with HMA refractory MDS showed anti-tumor activity with marrow complete response (mCR) and stable disease (SD); side effects were primarily low-grade, dose-dependent, and reversible (Lee et al. ASH 2019). In this abstract, we provide a subgroup analysis of the efficacy evaluable population with an update on mOS in the same population. Methods: This phase 1/2 study (NCT02649790) evaluated single-agent ELTA in pts with higher-risk MDS, ie, high-risk or intermediate-2 MDS by International Prognostic Scoring System (IPSS) and 5%-19% myeloblasts. Out of 20 pts enrolled, 15 pts were evaluable for efficacy and constitute the population studied in this analysis. Two doses of ELTA were evaluated: 10 mg (n=5) or 20 mg (n=15) every day for 5 days per week of a 28-day cycle. Results: As of 1 Feb 2021, the 15 pts evaluable for efficacy (median age 76 years; range 62-89) had a median of 2 prior treatment regimens (range 1-4); 93% had high/int-2 risk per IPSS. Of the 20 enrolled patients, 7 (35%) had mCR, and 5 (25%) had SD for a total disease control (mCR+SD) rate of 60%. Of the 15 pts evaluable for efficacy, 7 (47%) had mCR and 5 (33%) had SD. In the 10-mg cohort (n=5), all pts derived clinical benefit with 3 pts (60%) reaching mCR and 2 pts (40%) SD. In the 20-mg cohort (n=10), 4 pts (40%) had mCR and 3 (30%) had SD. Four pts had hematologic improvement (HI) and became transfusion independent for at least 8 weeks including 2 pts with tri-lineage HI. OS for pts who reached mCR (n=7) was significantly longer than for pts who did not reach mCR (n=8): median 11.86 vs 8.67 months (mo) (hazard ratio [HR]=0.27, p=0.05), and significantly longer than OS for pts with PD (n=3, mOS=3.15 mo, HR=0.23, p=0.04). Pts with disease control (n=12) had numerically longer mOS than pts with PD (9.86 vs 3.15 mo, HR=0.38, p=0.09). Pts with HI had a mOS of 10.58 months. Conclusions: Single-agent oral ELTA was active in pts with high-risk, HMA refractory MDS. Pts with mCR had significantly longer mOS than pts without mCR or with PD. Further evaluation of ELTA in MDS as a single agent and in combination with other agents is ongoing. Clinical trial information: NCT02649790.

Insurance status and survival of multiple myeloma (MM) patients

LBA107

Background: MM is often treated with oral antineoplastic medications (OAM). OAM prices have been rapidly escalating and there are well-described issues with affordability (Shih et al. JCO 2017). We therefore hypothesized that insurance status influences MM patients (pts) survival and interrogated the National Cancer Database (NCDB) to test this hypothesis. Methods: NCDB houses data on 70% of cancer pts in the USA. Data from 117,926 MM pts diagnosed between year 2005 and 2014 was analyzed. Primary outcome was overall survival (OS) which was analyzed using Kaplan-Meier method and Cox model. Results: Median age at diagnosis was 67 years (19-90); 55% were males. 57% of pts lived in areas where the median income was < $46k/year (individual income data was not available); Primary insurance was Medicare (52%), private insurance (35%) or Medicaid (5%), and 3% were uninsured. 40% were treated in academic institutions. Median follow up was 30 months (0-145). By univariate analysis, better OS was observed in pts with primary MM, lower Charlson Comorbidity Index (CCI), treatment in academic institutions, higher median regional income, or private insurance ( p<0.0001 for all). Median age of pts on Medicare, private insurance, Medicaid, or those without insurance was 74, 57, 58, and 57 years, respectively. When restricting the analysis to pts ≥ 65 years old, pts with private insurance had longer OS compared to Medicare pts (p<0.0001). The table shows the results of MV analysis. Conclusions: Insurance type and regional income are associated with MM survival. This may be related to affordability of OAM and merits further investigation. [Table: see text]

Unrecognized fluid overload during induction therapy increases morbidity in patients with acute promyelocytic leukemia

BACKGROUND

The combination of all-trans retinoic acid (ATRA) and arsenic trioxide (ATO) has proven to be the most effective therapy for patients with acute promyelocytic leukemia (APL). The majority of the morbidity and mortality from APL therapy occur during the induction phase. The objective of the current study was to identify the risk factors associated with transfer to the intensive care unit (ICU) and endotracheal intubation during induction therapy in patients with APL.

METHODS

The authors analyzed the clinical characteristics of 187 patients with newly diagnosed APL who were treated with ATRA and ATO with or without gemtuzumab ozogamicin. The authors documented the percentage change in body weight from baseline to the maximum recorded weight during induction or to the day of ICU transfer.

RESULTS

A total of 18 patients (10%) who initiated therapy with ATRA and ATO on a regular hospital floor required transfer to the ICU after a median of 12 days of induction therapy. The median volume of transfusions was 4350 mL (range, 60-30,750 mL). The volume of transfusions was the main factor associated with the risk of ICU transfer (odds ratio, 4.1; P < .001). Of the 18 patients transferred to the ICU, 10 patients (5%) required intubation. An increase in the total volume of transfusions, increase in weight ≥10% during induction therapy, and a plasma albumin level ≤3.2 g/dL at the time of diagnosis were found to be associated with an increased risk of endotracheal intubation.

CONCLUSIONS

Large volumes of blood product transfusions and unrecognized fluid overload during induction are associated with ICU transfer and endotracheal intubation in patients with APL. These can be prevented by limiting the amount of transfusions, careful monitoring for subtle signs of fluid overload, and early intervention with aggressive diuretic therapy.

Comparable survival of African-Americans and Caucasian patients with multiple myeloma: A hospital-based study including 117,926 patients

e18170

Background: Multiple Myeloma (MM) counts the most common hematologic malignance among African-Americans with twice the incidence of whites. The outcomes have greatly improved during the last 15 years, however with changing demographics there is an increasing focus on how various subgroups, based on race and ethnicity may be benefiting from survival improvement in MM. Previous studies showed that if access to care is assured, racial disparity-driven differences in outcome may be mitigated. Here, we conducted a study using the National Cancer Data Base (NCDB), which covers more than 70% of cancer pts in the USA, to evaluate survival patterns by race. Methods: MM patients (pts) diagnosed between years 2005 and 2014 and reported to the NCDB were analyzed (n = 117926). Pts were divided in three groups based on the year (y) of diagnosis (2005-07, 2008-10 and 2011-14). Kaplan-Meier method and log-rank test were used for overall survival analysis (OS). The effect size, hazard ratio (HR), of race on OS was estimated by Cox model adjusted by confounders. Results: Median age at diagnosis was 67 y (19 - 90); 55% were males. Median follow up was 30 months (m) (0 - 145). Median OS for white and black pts was 46 m (95% CI: 45.4 - 46.6) and 50.6 m (95% CI: 49.1 - 52.3), respectively (p < 0.0001). Black had longer OS compared to white pts by univariable analysis in all three study periods, noticeably with a trend toward higher survival benefit in most recent years. After adjusting for a variety of factors there was no statistically significant difference between the two racial groups (Table). Conclusions: This large study confirmed that after adjusting for confounding factors survival is similar for white and black MM pts. [Table: see text]

Phase 1 trial of anti-CD19 chimeric antigen receptor T (CAR-T) cells with tumor necrosis alfa receptor superfamily 19 (TNFRSF19) transmembrane domain

2539

Background: AntiCD19 CAR-T cells have shown encouraging anti-lymphoma activity. Decreasing the time from apheresis to CAR-T infusion can make this therapy available to pts with rapid progression. We present the interim results of a phase I clinical trial using on-site CAR-T manufacture. Methods: Adult pts with r/r CD19+ B cell lymphomas who failed ≥ 2 lines of therapy were enrolled. Autologous T cells were transduced with a lentiviral vector (Lentigen Technology, Inc,LTG1563) encoding an antiCD19 binding motif, CD8 linker and TNFRSF19 transmembrane region, and 4-lBB/CD3z domains. GMP-compliant manufacture was done using CliniMACS Prodigy, in a 12-day culture. Dose levels were 0.5, 1 and 2 x 106 CAR-T cells/kg. Lymphodepletion was done with cyclophosphamide (60mg/kg x 1) and fludarabine (25mg/m2/d x 3). Results: 7 pts (4 women, 3 men) were enrolled. Median age was 60y [range 43-69]. Diagnoses were DLBCL (n = 3) PMBCL, follicular lymphoma (FL), transformed FL, and transformed lymphoplasmacytic lymphoma; with a median of 4 previous treatments. Six pts had symptomatic refractory disease. CAR-T cell product manufacture was successful in all pts. Mean transduction rate was 44% [range 29-57]. CAR-T cell doses were 0.5 x 106/kg (n = 3) and 1 x 106/kg (n = 4). Median apheresis to infusion time was 13 days [range 13–20], 5 products were infused fresh. CAR-T persistence based on vector sequence, peaked in peripheral blood MNCs between days 14-21. Five pts are evaluable for safety. CRS grade 1 - 2 (Lee) occurred in 4 pts; with 3 requiring treatment. Grade 4 CRES (CARTOX-10) occurred in 1 pt, with resolution after corticosteroids; considered a DLT as it lasted more than 72 hours. No treatment-related mortality has occurred. 4/5 evaluable pts have achieved complete response. One pt did not respond and died. After a median follow up 3 months, all responding pts are alive and 1 relapsed 6 mo after treatment. Conclusions: Second generation antiCD19 CAR-T cells with TNFRS19 transmembrane domain have clinical activity against refractory NHL. Short manufacture time achieved by local CAR-T cell manufacture with the CliniMACS Prodigy enables treatment of a very high risk NHL population. Clinical trial information: NCT03434769.

Demographic characteristics of smoldering multiple myeloma patients: A hospital-based study including 11,643 patients

e13064

Background: SMM is the requisite asymptomatic phase that precedes Multiple Myeloma (MM). Observation until progression to MM has been the standard of care. However, the improvement in risk assessment and utility of chemoprevention strategies stemmed from large trials (e.g. QUIREDEX and E3A06) is beginning to shift the paradigm toward early detection of SMM by implementing screening strategies (e.g., PROMIS study). Lack of specific ICD code for SMM has been a major problem in epidemiologic studies aiming at characterizing the demographics and temporal dynamics of SMM. Here, we used the National Cancer Data Base (NCDB), which covers more than 70% of cancer pts in the USA, for this purpose. Methods: NCDB data from year 2010 to 2014 was analyzed. We defined SMM as pts with ICD-O 9732 that were placed on active surveillance or did not receive any therapy in the first 3 months (m) after diagnosis (Ravindran et al. Blood Cancer J. 2016). Institution size was categorized as small, medium and large if they reported < 10, 10-50, and > 50 cases per year, respectively. Results: Out of a total of 68234 MM pts, we identified 11643 (17%) with SMM. Median follow up was 32 m (0 - 85). Median age was 65 years (26 - 90), 52% were males, 71% were white and 24% were black. Median survival was 77.7 and 49.8 m for pts with SMM and MM, respectively ( p= 0.001). Median age at diagnosis of SMM was 62 and 66 years in blacks and whites, respectively ( p= 0.01). Over 87% of pts were diagnosed in small and medium size institutions (38% and 49%, respectively). Medicare was the main insurance payer (57%), followed by private insurance (32%) and Medicaid (5%), and 3% were not insured. The majority of pts (59.5%) lived in areas where the median income is less than $46K/year. Median distance traveled to treatment facility was 8.5 miles. During the first two years from diagnosis 18% needed treatment which is compatible with known estimated 10% per year risk of progression from SMM to MM. Conclusions: This large study of over 11,000 SMM pts highlights the national demographics of SMM diagnosed between years 2010 and 2014. Our results indicate that targeting small and medium size facilities should be an essential part of SMM screening strategies.

Early detection of transformation to BPDCN in a patient with MDS

Background

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare and aggressive hematologic malignancy characterized by neoplastic cells that are positive for CD123, CD4, BDCA2, and TCL1 and aberrant expression of CD56. Historically, patients with BPDCN have an unfavorable prognosis and the optimal treatment is not established due to lack of prospective data.

Case report

In this report we describe a patient with Felty’s syndrome and myelodysplastic syndrome (MDS) in whom a population of aberrant plasmacytoid dendritic cells emerged while on treatment with decitabine. Approximately 4 months later he transformed to leukemic BPDCN with skin and eye manifestations. Cytogenetic analysis showed diploid karyotype and molecular analysis showed mutations in KRAS, NOTCH1, and RUNX1 genes. He was treated with CD123-targeted therapy and had significant response in his marrow, skin, eyes, and functional status after one cycle.

Conclusion

The case demonstrates that minimal transformative disease of BPDCN may be detectable in patients with MDS well before fulminant progression. Early detection of emerging leukemic clones may allow for alternative monitoring and treatment considerations.

Investigational CHK1 inhibitors in early stage clinical trials for acute myeloid leukemia

Introduction: Acute myeloid leukemia (AML) is the most common myeloid malignancy in adults. Despite recent discoveries of targeted therapies, the frontline therapy consisting of chemotherapy remains unchanged for the past four decades. Like other cancers, AML is characterized by deranged DNA damage repair (DDR) pathway. Although impaired DDR may contribute to the pathogenesis of AML it also allows leukemia cells with damaged DNA to attempt repair resulting in resistance. CHK1 inhibitors reverse the cell cycle arrest, disallowing the cell to repair the chemotherapy-induced DNA damage, driving the cell to enter into mitotic catastrophe.Areas covered: This paper reviews the preclinical and clinical development of CHK1 inhibitors and we discussed their promising role as a potential addition to the therapeutic arsenal of AML.Expert opinion: Targeting the cell cycle checkpoints is an intriguing approach to treat cancer in general and AML in particular. CHK1 inhibitors in combination with chemotherapy have the potential of improving outcome in high-risk AML characterized by DDR activation.

Immune-related gene expression deficit of leukemia stem cells (LSC) in AML

7011

Background: AML LSC are believed to be responsible for residual and resistant leukemic disease leading to relapse. Understanding differences between bulk AML and the LSC subpopulation may allow the identification of novel LSC targets, especially for the most adverse risk AML where few patients are cured. Targeting LSC may be needed to eradicate AML, and immune-based therapies provide an approach for eliminating LSC. The transcriptional landscape of immune-related genes in LSC is not well understood. Methods: Samples were collected at diagnosis from 12 patients with high-risk AML prior to therapy. Bulk (CD45-dim blasts) and LSC (Lin-CD34+CD38-CD123+) AML marrow cells were FACS-sorted and analyzed using whole genome RNA-sequencing. Transcriptomes were analyzed using AltAnalyze software to identify differentially expressed genes in bulk AML cells and in AML LSC populations. These genes were further assessed by gene enrichment analysis using data from Gene Ontology (GO) and the Cancer Genome Atlas Project (CGAP). Results: Sixty-eight genes were identified with greater than 3-fold differential expression between bulk AML and LSC. GO enrichment analysis demonstrated more than 10-fold enrichment of genes involved in the molecular functions, biologic processes, and cell components related to the antigen presentation pathway, with the comparative down-regulation occurring in LSC. Among the top differentially expressed gene clusters, both the MHC class II and interferon-gamma signaling/response pathway gene expression was blunted in LSC. Additional expression analysis revealed that 42% of a CGAP-curated list of 201 antigen-processing and -presentation genes had significantly decreased expression in the LSC subpopulation compared to bulk AML. Conclusions: LSC from primary AML patient samples are characterized by reduction in expression of MHC class II receptor and antigen presentation genes compared to bulk AML. These results suggest that impairment in the presentation and/or processing of tumor associated antigens by MHC class II on LSC, along with tonic sponging of immune response cells and diversion away from LSC by bulk AML, may contribute to LSC evasion of immune surveillance and response.

Bortezomib, rituximab, and risk of graft-versus-host disease (GVHD) after BEAM conditioning for allogeneic stem cell transplantation (alloSCT)

e18543

Background: GVHD remains the main limitation of alloSCT and is exacerbated by the intensity of the conditioning regimen. In a recent study, the risk of acute grade II-IV GVHD and extensive chronic GVHD (cGVHD) after a nonmyelobaltive (NMA) regimen was 11%, and 26%, respectively (Khouri I. Blood 2014 124:2306). Higher rates were previously observed (32% and 54%, respectively) with the BEAM regimen. Based on clinical data showing a reduction in GVHD with the use of rituximab or bortezomib, we conducted a phase I/II study evaluating the addition of bortezomib to rituximab+BEAM in patients (pts.) who were not eligible for NMA alloSCT. Methods: Bortezomib was administered at 1.3 mg/m2 IV on days -13, -6, -1 and +2. The dose was later reduced to 1 mg/m2 after the occurrence of C. Difficile colitis in the first 3 pts. leading to 2 deaths. Rituximab was given on day -13 at a dose of 375 mg/m2, then at 1000 mg/m2 on days -6, +1, and +8 of alloSCT. BEAM was administered between days -6 and -1. All pts. received our standard GVHD prophylaxis with tacrolimus and methotrexate. In addition, thymoglobulin 1 mg/kg IV was given on days -2, and -1 in patients receiving matched unrelated donor (MUD) or mismatched (MM) transplants. Results: Thirty-nine pts. were studied. Median age was 54 yrs. Thirteen (33%) and 26 (67%) pts. had indolent or aggressive lymphoma histologies, respectively. Sixteen (41%) pts. were refractory. Twenty-two (56%) received alloSCT from HLA-compatible siblings, 16 (41%) from MUDs and 1 (3%) from mm donors. Peripheral blood was the source of stem cells in 97% of pts. ABO and CMV-mismatch rates were 56% had 50%, respectively. Median follow up surviving patients was 65 mos. Five-year OS and PFS rates were 35% and 28%, respectively. The CI of acute grade II-IV, III-IV, and cGVHD were 55%, 34%, and 41%, respectively. No predictor for acute GVHD was identified. Instead, we found that sex-mismatched transplants were predictive of a higher risk of cGVHD ( P= 0.01). Conclusions: The current trial is the first one evaluating the safety and efficacy of bortezomib plus rituximab as a part of the BEAM regimen for alloSCT. A better prophylaxis regimen is needed to lessen the risk of GVHD in this setting. Clinical trial information: NCT00439556.

Surveillance of antimicrobial resistance in Lebanese hospitals: retrospective nationwide compiled data

Antimicrobial resistance is closely linked to antimicrobial use and is a growing concern worldwide. Antimicrobial resistance increases healthcare costs substantially in many countries, including Lebanon. National data from Lebanon have, in the most part, been limited to a few academic hospitals. The Lebanese Society of Infectious Diseases conducted a retrospective study to better describe the antimicrobial susceptibility patterns of bacterial isolates in Lebanon. Data were based on records retrieved from the bacteriology laboratories of 16 different Lebanese hospitals between January 2011 and December 2013. The susceptibility results of a total 20684 Gram-positive and 55594 Gram-negative bacteria were analyzed. The prevalence rate of methicillin-resistant Staphylococcus aureus was 27.6% and of vancomycin-resistant Enterococcus spp was 1%. Streptococcus pneumoniae had susceptibilities of 46% to oxacillin, 63% to erythromycin, and 98% to levofloxacin. Streptococcus pyogenes had susceptibilities of 94% to erythromycin and 95% to clindamycin. The mean ampicillin susceptibility of Haemophilus influenzae, Salmonella spp, and Shigella spp isolates was 79%, 81.3%, and 62.2%, respectively. The extended-spectrum beta-lactamase production rate for Escherichia coli was 32.3% and for Klebsiella spp was 29.2%. Acinetobacter spp showed high resistance to most antimicrobials, with low resistance to colistin (17.1%). Pseudomonas spp susceptibilities to piperacillin-tazobactam and imipenem were lower than 80% (79.7% and 72.8%, respectively). This study provides population-specific data that are valuable in guiding antimicrobial use in Lebanon and neighbouring countries and will help in the establishment of a surveillance system for antimicrobial resistance following the implementation of a nationwide standardization of laboratory methods and data entry.