Aging is characterized by clonal expansion of myeloid-biased hematopoietic stem cells and by an increased risk of myeloid malignancies. Exome sequencing of 3 elderly females with clonal hematopoiesis demonstrated by X-inactivation analysis identified somatic TET2 mutations. Recurrence testing found TET2 mutations in 10 out of 182 individuals with X-inactivation skewing. TET2 mutations were specific to individuals with clonal hematopoiesis without hematologic malignancies and were associated with alterations in DNA methylation.

Loss of Asxl1 results in myelodysplastic syndrome, whereas concomitant deletion of Tet2 restores HSC self-renewal and triggers a more severe disease phenotype distinct from that seen in single-gene knockout mice.

Background: Sinus tachycardia in cancer reflects a significant multi-system organ stressor and disease, with sparse literature describing its clinical significance. We assessed cardiovascular (CV) and mortality prognostic implications of sinus tachycardia in cancer patients. Methods: We conducted a case-control study of 622 cancer patients at a U.S. urban medical center from 2008 to 2016. Cases had ECG-confirmed sinus tachycardia [heart rate (HR) ≥100 bpm] in ≥3 different clinic visits within 1 year of cancer diagnosis excluding a history of pulmonary embolism, thyroid dysfunction, left ventricular ejection fraction <50%, atrial fibrillation/flutter, HR >180 bpm. Adverse CV outcomes (ACVO) were heart failure with preserved ejection fraction (HFpEF), HF with reduced EF (HFrEF), hospital admissions for HF exacerbation (AHFE), acute coronary syndrome (ACS). Regression analyses were conducted to examine the effect of sinus tachycardia on overall ACVO and survival. Results: There were 51 cases, age and sex-matched with 571 controls (mean age 70±10, 60.5% women, 76.4% Caucasian). In multivariate analysis over a 10-year follow-up period, sinus tachycardia (HR ≥100 vs.

Multiple myeloma remains an incurable disease with the usual disease course requiring induction therapy, autologous stem cell transplantation for eligible patients, and long-term maintenance. Risk stratification tools and cytogenetic alterations help inform individualized therapeutic choices for patients in hopes of achieving long-term remissions with preserved quality of life. Unfortunately, relapses occur at different stages of the course of the disease owing to the biological heterogeneity of the disease. Addressing relapse can be complex and challenging as there are both therapy- and patient-related factors to consider. In this broad scoping review of available therapies in relapsed/refractory multiple myeloma (RRMM), we cover the pharmacologic mechanisms underlying active therapies such as immunomodulatory agents (IMiDs), proteasome inhibitors (PIs), monoclonal antibodies (mAbs), traditional chemotherapy, and Venetoclax. We then review the clinical data supporting the use of these therapies, organized based on drug resistance/refractoriness, and the role of autologous stem cell transplant (ASCT). Approaches to special situations during relapse such as renal impairment and extramedullary disease are also covered. Lastly, we look towards the future by briefly reviewing the clinical data supporting the use of chimeric antigen receptor (CAR-T) therapy, bispecific T cell engagers (BITE), and Cereblon E3 Ligase Modulators (CELMoDs).

No abstract

Introduction: Assessment of cardiac function after treatment for breast cancer relies on interval evaluation of ventricular function through echocardiography. Women who undergo mastectomy more frequently choose to undergo breast reconstruction with implant. This could impede assessment of cardiac function in those with leftsided implant. We aimed to examine whether left-sided breast reconstruction with tissue expanders (TE) affect echo image acquisition and quality, possibly affecting clinical decision-making. Methods: A retrospective case-control study was conducted in 190 female breast cancer patients who had undergone breast reconstruction with TE at an urban academic center. Echocardiographic technical assessment and image quality were respectively classified as excellent/good or adequate/technically difficult by technicians; and excellent/good or adequate/poor by 2 board-certified cardiologist readers. Likelihood ratio was used to test multivariate associations between image quality and left-sided TE. Results: We identified 32 women (81.3% white; mean age 48 years) with left-sided/bilateral TE, and 158 right-sided/ no TE (76.6% white, mean age 57 years). In multivariable analyses, we found a statistically significant difference in technician-assessed difficulty in image acquisition between cases and controls (p = 0.01); but no differences in physician-assessed image quality between cases and controls (p = 0.09, Pearson's r = 0.467). Conclusions: Left-sided breast TE appears to affect the technical difficulty of echo image acquisition, but not physician-assessed echo image quality. This likely means that echo technicians absorb most of the impediments associated with imaging patients with breast TE such that the presence of TE has no bearing on downstream clinical decision-making associated with echo image quality.

e20721 Background: Pemetrexed maintenance therapy is associated with superior survival in stage IV nsqNSCLC patients. We have observed long term disease control in some patients treated with at least one cycle of Pem/Plat with potential for maintenance pem. There are no reports of data regarding long term PFS and OS in patients treated with Pem regimens. The objectives of our retrospective analysis are to determine the frequency of long term disease control on Pem maintenance and to identify parameters associated with longer PFS/OS. Methods: We included all patients with Stage IV nsqNSCLC who received at least one cycle of pem/plat between May 2010 and Nov 2013. We identified 240 patients from our database and analyzed their demographics, lab values, dates of therapy, and dates of progression. PFS/OS was estimated by the Kaplan-Meier method and associations with patient characteristics were assessed by log-rank tests and Cox proportional hazards analysis. The shortest potential follow up was 5 years. Results: Median age was 66 years, 60% were female, and 72% were Caucasian. Baseline ECOG performance status was 0(22%), 1(50%) and ≥ 2(22%). Median PFS was 6.2 months. At 1, 2, 3, 4, and 5 years of follow up absence of disease progression was seen in 33%, 14%, 7.5%, 4%, and 3%, respectively. Additionally, in terms of OS at 1-5 years, we observed 54.5%, 35%, 21%, 14%, and 11%. Lower baseline neutrophil: lymphocyte ratio (NLR) was strongly associated with improved PFS when using NLR≤5 vs > 5 (median PFS 13.2 mo vs 5.6 mo) Additionally, baseline Hemoglobin (mean = 12.03 g/dL, HR = .904, p = .0046) and Albumin (mean 3.3 g/dL, HR = .7722, p = .024) were associated with better PFS. Conclusions: The similarity in median PFS in our patients (6.2 mo) and clinical trial data suggests that our group of real world patients did not have uniquely favorable baseline characteristics. However, the patients most likely to reach long PFS/OS milestones had favorable baseline prognostic indicators suggesting that this patient subset might also be most likely to benefit from the recently approved regimen which combined Pembrolizumab with Pemetrexed/Carboplatin.

308 Loss-of-function somatic mutations in Addition of Sex Combs Like 1 (ASXL1) occur in a subset of patients with myeloid malignancies, most commonly in myelodysplastic syndrome (MDS). In addition, germline mutations in ASXL1 are observed in patients with Bohring-Opitz Syndrome, a developmental disorder characterized by neurologic and skeletal abnormalities. Previous work characterizing a constitutive gene-trap Asxl1 model was notable for significant perinatal lethality of Asxl1−/− mice with evidence of an overt hematopoietic phenotype in surviving mice. Given the lack of detailed data on the hematopoietic phenotype of Asxl1 loss in vivo, we created a murine model for conditional knockout of Asxl1 for tissue- and temporal-specific deletion with 4 different Cre recombinase alleles. We crossed our conditional Asxl1 allele to EIIa-cre to generate mice with germline loss of Asxl1; this revealed embryonic lethality of mice with homozygous germline Asxl1 loss. Mice with heterozygous germline deletion of Asxl1 were viable and fertile although a significant proportion had cranio-facial abnormalities. Timed-sacrifice of pregnant mothers from heterozygous EIIa-cre Asxl1+/− crosses revealed that homozygous Asxl1−/− pups survived to 18–20.5 days post-coitus, with all embryos characterized by craniofacial abnormalities including anopthalmia, microcephaly, cleft palates, and mandibular malformations similar to those seen with Bohring-Opitz syndrome. We then generated mice with conditional Asxl1 deletion in the hematopoietic compartment by crossing floxed mice with Vav-cre recombinase mice for hematopoietic deletion at birth, and with Mx1-cre mice for inducible deletion of Asxl1. Deletion of Asxl1 in both systems resulted in complete loss of Asxl1 as assessed by Western blot. In both models we noted progressive development of leukopenia and anemia in mice with homozygous loss of Asxl1 compared to age-matched controls (Figure). This was associated with extramedullary hematopoiesis and morphologic evidence of myeloid, erythroid, and megakaryocytic dysplasia, similar to that observed in human MDS (Figure). Flow cytometry revealed a progressive increase in immunophenotypically-defined multipotent progenitors (Lineage-negative, Sca1+, cKIT+, CD150-, CD48+ cells) in bone marrow and spleen of knockout (KO) mice. Characterization of HSC's from 6-week old Vav-cre Asxl1−/− mice using serial competitive transplantation revealed a competitive disadvantage with transplantation of SLAM+ cells from 6-week old KO mice. A subset of Vav-cre Asxl1−/− mice developed a transplantable, monocytic-like leukemia beyond 6 months of age which was characterized by both proliferative and dysplastic features. Restriction of Asxl1 deletion to the megakaryocytic compartment using Pf4-cre revealed an age-specific decline in platelet production in Pf4-cre Asxl1−/− mice compared to age-matched controls, and a concomitant increase in bone marrow megakaryocytes in KO mice. Consistent with previous in vitro studies, hematopoietic-specific deletion of Asxl1 was associated with a marked decrease in H3K27me3 as assessed by histone Western blots of murine splenocytes and H3K27me3 ChIP-Seq of myeloid progenitors from 1 year-old Vav-cre Asxl1−/− mice compared with littermate controls. RNA-Seq from myeloid progenitors was integrated with H3K4me3/K27me3 ChIP-Seq to identify gene targets of Asxl1 loss associated with myelodysplasia. Given that MDS patients frequently present with concomitant ASXL1 and TET2 mutations, Vav-cre Asxl1fl/fl mice were also crossed with mice bearing floxed alleles of Tet2. Mice with combined hematopoietic-specific deletion of both Asxl1 and Tet2 developed bone marrow failure and hastened death compared with age-matched, single-gene deleted counterparts at 25 to 40 weeks of age. The findings here reveal that hematopoietic-specific deletion of Asxl1 results in progressive ineffective hematopoiesis, an increase in hematopoietic progenitors, a propensity for leukemic transformation with age, and morphologic features of human MDS (Figure). Combining Asxl1 deletion with loss of Tet2, a combined genotype present in at least 5% of patients with de novo MDS, resulted in shorter latency, progressive MDS. These data suggest that these two models represent novel, genetically accurate models of MDS amenable to epigenomic, functional and preclinical therapeutic studies. Disclosures: No relevant conflicts of interest to declare.