Citations 648

Targeting CD123 in hematologic malignancies: identifying suitable patients for targeted therapy

Leukemia & Lymphoma | May 17, 2021 | Volume: 62 | Issue: 11 | Pages: 2568-2586

10.1080/10428194.2021.1927021 | PMID 33999767

Pathology, Radiology, and Genetics of Interstitial Lung Disease in Patients With Shortened Telomeres

American Journal of Surgical Pathology | May 3, 2021 | Volume: 45 | Issue: 7 | Pages: 871-884

10.1097/pas.0000000000001725 | PMID 33935155

Interstitial lung diseases (ILDs) in patients with shortened telomeres have not been well characterized. We describe demographic, radiologic, histopathologic, and molecular features, and p16 expression in patients with telomeres ≤10th percentile (shortened telomeres) and compare them to patients with telomere length >10th percentile. Lung explants, wedge biopsies, and autopsy specimens of patients with telomere testing were reviewed independently by 3 pathologists using defined parameters. High-resolution computed tomography scans were reviewed by 3 radiologists. p16-positive fibroblast foci were quantified. A multidisciplinary diagnosis was recorded. Patients with shortened telomeres (N=26) were morphologically diagnosed as usual interstitial pneumonia (UIP) (N=11, 42.3%), chronic hypersensitivity pneumonitis (N=6, 23.1%), pleuroparenchymal fibroelastosis, fibrotic nonspecific interstitial pneumonia, desquamative interstitial pneumonia (N=1, 3.8%, each), and fibrotic interstitial lung disease (fILD), not otherwise specified (N=6, 23.1%). Patients with telomeres >10th percentile (N=18) showed morphologic features of UIP (N=9, 50%), chronic hypersensitivity pneumonitis (N=3, 16.7%), fibrotic nonspecific interstitial pneumonia (N=2, 11.1%), or fILD, not otherwise specified (N=4, 22.2%). Patients with shortened telomeres had more p16-positive foci (P=0.04). The number of p16-positive foci correlated with outcome (P=0.0067). Thirty-nine percent of patients with shortened telomeres harbored telomere-related gene variants. Among 17 patients with shortened telomeres and high-resolution computed tomography features consistent with or probable UIP, 8 (47.1%) patients showed morphologic features compatible with UIP; multidisciplinary diagnosis most commonly was idiopathic pulmonary fibrosis (N=7, 41.2%) and familial pulmonary fibrosis (N=5, 29%) in these patients. In conclusion, patients with shortened telomeres have a spectrum of fILDs. They often demonstrate atypical and discordant features on pathology and radiology leading to diagnostic challenges.
Clinical, molecular, and prognostic comparisons between CCUS and lower-risk MDS: a study of 187 molecularly annotated patients

Blood Advances | April 28, 2021 | Volume: 5 | Issue: 8 | Pages: 2272-2278

10.1182/bloodadvances.2020003976 | PMID 33904893

Venetoclax with azacitidine or decitabine in blast‐phase myeloproliferative neoplasm: A multicenter series of 32 consecutive cases

American Journal of Hematology | April 12, 2021 | Volume: 96 | Issue: 7 | Pages: 781-789

10.1002/ajh.26186 | PMID 33844862

Abstract Venetoclax (Ven) combined with a hypomethylating agent (HMA) has now emerged as an effective treatment regimen for acute myeloid leukemia, in both de novo and relapsed/refractory setting. The current multicenter study retrospectively examined Ven + HMA treatment outcome among 32 patients (median age 69 years; 59% males) with blast‐phase myeloproliferative neoplasm (MPN‐BP). Pre‐leukemic phenotype included essential thrombocythemia (ET)/post‐ET myelofibrosis (34%), polycythemia vera (PV)/post‐PV myelofibrosis (38%) and primary myelofibrosis (28%). Twenty‐nine study patients were fully annotated cytogenetically and molecularly (NGS): 69% harbored complex karyotype and/or mutations, including TP53 (41%), IDH1/2 (21%), ASXL1 (21%), N/KRAS (14%), SRSF2 (10%), EZH2 (10%) and U2AF1 (7%). All patients received Ven combined with either azacitidine ( n = 12) or decitabine ( n = 20); either up front ( n = 23) or after failing another induction therapy ( n = 9). Complete remission with (CR) or without (CRi) count recovery was achieved in 14 (44%) patients and was more likely to occur in the absence of pre‐leukemic PV/post‐PV myelofibrosis phenotype ( p < .01), complex karyotype ( p < .01) or K/NRAS ( p = .03) mutations; seven of eight patients (88%) without vs four of 21 (19%) with complex karyotype or K/NRAS mutation achieved CR/CRi ( p < .01); all 11 informative patients with pre‐leukemic PV/post‐PV myelofibrosis phenotype displayed complex karyotype ( p < .01). In contrast, neither TP53 ( p = .45) nor IDH1/2 ( p = .63) mutations affected response. Compared to historical controls treated with HMA alone ( n = 26), the CR/CRi rate (44% vs 4%) and median survival (8 vs 5.5 months) were more favorable with Ven + HMA, but without significant difference in overall survival. Importantly, six patients with CR/CRi subsequently received allogeneic hematopoietic stem cell transplant (AHSCT). Note, Ven + HMA produces robust CR/CRi rates in MPN‐BP, especially in the absence of RAS mutations and complex karyotype, thus enabling AHSCT, in some patients.
Clinical correlates and prognostic impact of clonal hematopoiesis in multiple myeloma patients receiving post‐autologous stem cell transplantation lenalidomide maintenance therapy

American Journal of Hematology | February 14, 2021 | Volume: 96 | Issue: 5 | Pages: No page available

10.1002/ajh.26125 | PMID 33580975

Systemic Mastocytosis: A Concise Clinical and Laboratory Review

Archives of Pathology & Laboratory Medicine | February 11, 2021 | Volume: 131 | Issue: 5 | Pages: 784-791

10.5858/2007-131-784-smacca | PMID 17488167

Abstract Context. —Systemic mastocytosis is characterized by abnormal growth and accumulation of neoplastic mast cells in various organs. The clinical presentation is varied and may include skin rash, symptoms related to release of mast cell mediators, and/or organopathy from involvement of bone, liver, spleen, bowel, or bone marrow. Objective. —To concisely review pathogenesis, disease classification, clinical features, diagnosis, and treatment of mast cell disorders. Data Sources. —Pertinent literature emerging during the last 20 years in the field of mast cell disorders. Conclusions. —The cornerstone of diagnosis is careful bone marrow histologic examination with appropriate immunohistochemical studies. Ancillary tests such as mast cell immunophenotyping, cytogenetic/molecular studies, and serum tryptase levels assist in confirming the diagnosis. Patients with cutaneous disease or with low systemic mast cell burden are generally managed symptomatically. In the patients requiring mast cell cytoreductive therapy, treatment decisions are increasingly being guided by results of molecular studies. Most patients carry the kit D816V mutation and are predicted to be resistant to imatinib mesylate (Gleevec) therapy. In contrast, patients carrying the FIP1L1-PDGFRA mutation achieve complete responses with low-dose imatinib therapy. Other therapeutic options include use of interferon-α, chemotherapy (2-chlorodeoxyadenosine), or novel small molecule tyrosine kinase inhibitors currently in clinical trials.
Pre- Transplant Ferritin Predicts Overall Survival and Non-Relapse Mortality in Patients Undergoing Allogeneic Hematopoietic Cell Transplantation for Myelofibrosis

Blood | February 8, 2021 | Volume: 136 | Issue: Supplement 1 | Pages: 19-20

10.1182/blood-2020-141414

Background: Elevated serum ferritin (SF) is common in patients with myelofibrosis (MF) given the frequent red-cell transfusion requirements and impaired iron metabolism. The dysregulation of iron metabolism is associated with increased hepcidin levels which predict for inferior survival in patients with MF (Pardanani et al AJH 2013). High pre-transplant SF negatively impacts overall survival and non-relapse mortality in patients undergoing allogeneic hematopoietic cell transplantation (allo-HCT) for hematological malignancies (Chee et al BMT 2017 & Yan et al 2018). However, the impact of elevated pre-transplant SF specifically on post-alloHCT outcomes has not been described in MF. Methods: We conducted a retrospective study of patients with MF undergoing allo-HCT at Mayo clinic Rochester, Arizona, and Florida from January 1st 2012 - December 31st 2019. We abstracted demographic and outcome variables to evaluate the impact of pre-transplant ferritin levels on post-transplant outcomes. We used a Receiver Operand Characteristic Curve to identify a pre-transplant serum ferritin (SF) of ≥ 1,123 ng/mL as the cutoff which best correlated with poor survival. Results: We identified 67 patients with MF who underwent allo-HCT during the study period with readily available data. Patients with a pre-transplant ferritin ≥ 1,123 ng/mL (n=18) had a median age of 59.4 years and were predominantly male (n=9, 50%) with primary myelofibrosis (n=12, 67%), had a DIPSS-plus int-2 (n=10, 56%) and high (n=6, 33%) risk categories and received a reduced-intensity conditioning (n=14, 78%) from a matched-unrelated donor (n=7, 50%) Table1. Patients with SF ≥ 1,123 ng/mL had a worse overall survival (OS) (median OS= 12.64 months [95%CI=6.08-19.20 months] vs. not-reached (NR) p=0.001). Patients with elevated SF had an increased non-relapse mortality (NRM) rate at 6 months (16.7%, [95%CI=0.4-37.2%]) vs 8.2%,[95%CI= 2.6-18.1%] p=0.021) and 12 months (33.3% [95%CI=13.0-55.4%] vs 10.4% [95%CI=3.8-21.0%] p=0.021) Patients with ≥ 1,123 ng/mL SF had a non-statistically significant higher rate of acute graft-vs-host disease grades 3-4 (28% vs 12.2% p=0.13) but similar rates of moderate to severe chronic graft-vs-host disease (31% vs 28% p=0.78). In the univariate analysis, SF ≥1,123 ng/mL and a Hematopoietic stem cell transplant comorbidity index (HCT-CI) ≥3 were associated with an increased risk of mortality (Hazard ratio [HR]=4.18 [95%CI=1.64-10.62] p=0.003] and HR=4.42 [95%CI=1.70-11.46] p=0.003, respectively). Both retained significance in multivariate analysis SF ≥1,123 ng/mL (HR= 2.80 [95%CI= 1.0-7.6], p=0.04)] and HCT-CI score ≥ 3 (HR 3.10 [95%CI= 1.12-8.62, p=0.03]) after adjusting for age, DIPSS-plus score, conditioning regimen intensity, donor type, CMV risk, prior use of ruxolitinib, and ABO mismatch. We grouped the patients into low, intermediate and high risk categories using SF level and HCT-CI scores as detailed in Figure 1. The risk category based on SF and HCT-CI was statistically significant in impacting OS and NRM in this cohort. The 12 month OS rate was lower in the high risk category (44.4% [95%CI= 13.6%-71.9%]) when compared to the intermediate (64.6%, [95%CI=39.7%-81.3%]) and low risk (91.9%, [95%CI= 76.9%-97.3%], p=0.0002) categories. Similarly, the 12 month NRM rate was higher in the high risk category (44.4%, [95%CI=11.0%-74.2%]) when compared to the intermediate (25%, [95%CI=8.7%-45.5%]) and low risk (5.3% [95%CI=0.9%-15.9%], p=0.0046) categories. Conclusion: In patients undergoing allogeneic SCT for myelofibrosis, serum ferritin ≥ 1,123 ng/mL is a predictor of high NRM and inferior OS. Combining ferritin serum levels with HCT-CI may help in better patient selection for allo-HCT in MF population. Larger patient cohort is warranted to confirm our findings. Disclosures Kharfan-Dabaja: Daiichi Sankyo: Consultancy; Pharmacyclics: Consultancy. Shah:Dren Bio: Consultancy.
Predictors of Survival and Time to Progression to Myeloid Neoplasm in Patients with Clonal Cytopenias

Blood | February 8, 2021 | Volume: 136 | Issue: Supplement 1 | Pages: 26-27

10.1182/blood-2020-142181

Background: Clonal cytopenias of Undetermined Significance (CCUS) have a higher risk of progression to myeloid neoplasm (MN) compared to idiopathic cytopenias of undetermined significance (ICUS) (Malcovati et al., Blood, 2017). The implementation of flow cytometric (FC) immune-phenotyping and next generation sequencing (NGS) in clinical practice has improved the diagnosis of these entities but the clinical significance and interaction of these abnormal results are still unknown. In this study we investigated predictive factors that play role in survival and progression to MN in patients with ICUS/CCUS. Methods: Patients (Pts) who had undergone evaluation for unexplained cytopenia and had undergone FC and bone marrow morphological assessment between 3/2015-3/2020 at Mayo Clinic Rochester were included. Pts were excluded if a malignant hematological disorder was diagnosed prior to the time of FC. FC included evaluation of the following parameters: Abnormal expression of HLA-DR/CD13, CD2, CD7, CD45, and CD56 on blasts; and abnormal CD13/CD16 expression and side scatter on granulocytic cells. NGS panel up to 2018 included 34 genes, ASXL1, BCOR, BRAF, CALR, CBL, CEBPA, CSF3R, DNMT3A, ETV6, EZH2, FLT3, GATA1, GATA2, IDH1, IDH2, JAK2, KIT, KRAS, MPL, MYD88, NOTCH1, NPM1, NRAS, PHF6, PTPN11, RUNX1, SETBP1, SF3B1, TERT, TET2, TP53, U2AF1, WT1, and ZRSR2; in 2018, BRAF was omitted and 12 genes were added, ANRD26, DDX41, ELANE, ETNK1, KDM6A, MYD88, NOTCH1, RAD21, SH2B3, SRP72, SMC3, and STAG2. Results: Characteristics: Of 490 consecutive pts, 238 (median age 69 years (range 19-92), 66% males) met our inclusion criteria as ICUS. 86 (36%) pts had CCUS (abnormal cytogenetics and/or tested positive for pathogenic mutations on NGS). After a median follow-up of 28 months (95% CI: 20 to 31 months), 21 (25%) patients developed MN and 23 (27%) died during follow-up. Comparing ICUS vs CCUS: upon comparing CCUS pts to ICUS, several factors were found to be significantly different: CCUS pts were older (p= .02); majority male (p= .04), had more abnormal HLA-DR/CD13 (p &lt;.0001), more side-scattered light by FC (p &lt;.0001), more pancytopenia on follow up (p= .02) and more morphologic atypia (&lt;.0001). Overall survival (OS) outcomes in CCUS: Several covariates were significant in univariate models, and model selection was used to generate a risk score based on abnormal CD7, abnormal CD13/CD16, abnormal HLA-DR/CD13, splenomegaly and history of prior chemotherapy or radiotherapy (range: 0 - 4; HR=2.58, [95 CI: 1.69 - 3.94], p&lt;.0001). Risk scores were grouped as low risk (score=0), intermediate risk (score=1), and high risk (score=2+), with estimated 2-yr-OS of 95%, 84%, 40%, respectively (Figure 1). An extended risk score model including NGS factors added ASXL1 and IDH1 mutation status to the previous model (range: 0 - 6; HR=2.72, [95 CI 1.82 - 4.06], p&lt;0.0001). MN-free survival (MNFS) in CCUS: 37 pts either progressed to MN and/or died with a median follow up time for MNFS of 22.4 months. Similar for OS, model selection approaches yielded a composite risk score: splenomegaly, BCOR mutation status, mutation in RAS signaling pathway, abnormal expression of flow markers CD13/CD16, HLA-DR/CD13 or CD7 (HR=3.23, [95 CI: 1.90 - 5.49], p=&lt;0.0001). Risk scores were grouped as low risk (score=0), intermediate risk (score=1), and high risk (score ≥ 2), with estimated 1-yr MNFS of 84%, 74%, and 31%, respectively (Figure 2). Conclusion: CCUS has unique features compared to ICUS. Several factors, including clinical characteristics, immune-phenotyping by FC, and somatic mutations have important impact on risk of progression to MN and on overall survival. Our findings serve as proof-of-concept that such integrated models could help identify CCUS patients at higher risks for progression to MN or death. They can guide treatment accordingly and should be evaluated further. Disclosures Shah: Dren Bio: Consultancy.
Imerge: A Phase 3 Study to Evaluate Imetelstat in Transfusion-Dependent Subjects with IPSS Low or Intermediate-1 Risk Myelodysplastic Syndromes (MDS) That Is Relapsed/Refractory to Erythropoiesis-Stimulating Agent (ESA) Treatment

Blood | February 8, 2021 | Volume: 136 | Issue: Supplement 1 | Pages: 17-17

10.1182/blood-2020-138810

Background: Current treatment options for red blood cell (RBC) transfusion-dependent (TD) patients with lower risk (LR) myelodysplastic syndromes (MDS) relapsed after or refractory to erythropoiesis-stimulating agents (ESAs) have limited efficacy and durability; new approaches are needed. Imetelstat is a 13-mer lipid-conjugated oligonucleotide that targets the RNA template of human telomerase and is a competitive inhibitor of telomerase enzymatic activity (Asai et al, Cancer Res 2003; Herbert et al, Oncogene 2005). Preclinical, in vivo xenograft models (Dikmen et al, Cancer Res 2005; Hochreiter et al, Clin Cancer Res 2006) and preliminary clinical data from a pilot study (Tefferi et al, Blood Cancer J 2016) supported initiation of a study in TD LR MDS patients. The Phase 2 part of IMerge demonstrated an 8-week RBC transfusion independence (RBC-TI) rate of 42%, 24-week RBC-TI rate of 32%, with median duration of TI being 88 weeks. The responses were seen across different subtypes of LR MDS (Platzbecker et al, EHA 2020, S183). No new safety signal was identified. These results support the Phase 3 part of the trial. Methods: IMerge is two-part, Phase 2/3 study (ClinicalTrials.gov: NCT02598661). The Phase 2 portion of the study described above is closed for enrolment. The Phase 3 portion of the study is open for enrollment of adult patients with International Prognostic Scoring System (IPSS) low or intermediate-1 risk, non-del(5q) MDS, who are TD, are relapsed after or refractory to ESAs, and have not received treatment with lenalidomide or hypomethylating agents. The study is a randomized (2:1) double-blind, placebo-controlled trial to compare efficacy of imetelstat vs. placebo that will enroll approximately 170 patients and will be conducted at approximately 130 centers in North America, Europe, Asia and Middle East. Imetelstat will be administered as 2-hour IV infusion every 4 weeks at 7.5 mg/kg. The primary endpoint of the study is to assess the rate of RBC-TI lasting ≥8 weeks. Secondary endpoints include safety, rate of RBC-TI ≥24 weeks, time to RBC-TI start, RBC-TI duration, rate of hematologic improvement-erythroid (HI-E), the amount and relative change in RBC transfusions, rate of complete response or partial response, overall survival, progression of MDS, pharmacokinetics, and effect of treatment on quality of life. Biomarkers relevant to the mechanism of action of imetelstat will be assessed to demonstrate target inhibition and their association with clinical responses. Cytogenetics and mutation analyses will be performed to evaluate the impact of imetelstat on reduction/depletion of malignant clones leading to disease modification. Disclosures Platzbecker: AbbVie: Consultancy, Honoraria; Novartis: Consultancy, Honoraria, Research Funding; BMS: Consultancy, Honoraria; Takeda: Consultancy, Honoraria; Geron: Consultancy, Honoraria; Amgen: Honoraria, Research Funding; Janssen: Consultancy, Honoraria, Research Funding. Fenaux:Abbvie: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; BMS: Honoraria, Research Funding; Jazz: Honoraria, Research Funding. Steensma:CRISPR: Current equity holder in publicly-traded company; Aprea Therapeutics: Research Funding; Takeda: Consultancy; BMS/Celgene: Consultancy; Onconova: Consultancy; Arena: Current equity holder in publicly-traded company; H3 Biosciences: Research Funding; Astex Pharmaceuticals, Otsuka: Consultancy; Arrowhead Pharmaceuticals: Current equity holder in publicly-traded company. Font:Abbvie: Other: Travel, accommodations, expenses; Menarini: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees, Other: Travel, accommodations, expenses, Speakers Bureau; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Travel, accommodations, expenses; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees. Diez-Campelo:Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Celgene BMS: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau. Thepot:astellas: Honoraria; novartis: Honoraria; sanofi: Honoraria; celgene: Honoraria. Jang:Bristol Myers Squibb: Research Funding; Abbvie: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Honoraria, Research Funding. Sherman:Geron Corp: Current Employment, Current equity holder in publicly-traded company. Dougherty:Geron Corp: Current Employment, Current equity holder in publicly-traded company. Sun:Geron Corp: Current Employment, Current equity holder in publicly-traded company. Huang:Geron Corp: Current Employment, Current equity holder in publicly-traded company. Wan:Geron Corp: Current Employment, Current equity holder in publicly-traded company. Rizo:Geron Corp: Current Employment, Current equity holder in publicly-traded company. Berry:Geron Corp: Current Employment, Current equity holder in publicly-traded company. Feller:Geron Corp: Current Employment, Current equity holder in private company. Santini:Takeda: Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Honoraria; Acceleron: Consultancy; Takeda: Consultancy, Honoraria; Menarini: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; BMS: Consultancy, Honoraria; Johnson & Johnson: Honoraria.
A Multicenter Phase 1/2 Clinical Trial of Tagraxofusp, a CD123-Targeted Therapy, in Patients with Poor-Risk Primary and Secondary Myelofibrosis

Blood | February 8, 2021 | Volume: 136 | Issue: Supplement 1 | Pages: 39-40

10.1182/blood-2020-137572

Study Rationale: At present there are no effective therapies for patients with primary or secondary myelofibrosis (MF) after the failure of the JAK inhibitory class of therapies. Furthermore, patients with monocytosis, thrombocytopenia, accelerated phase, or high-risk genetic features fare poorly with JAK inhibitors (JAKi), as intolerance, resistance, and/or ineligibility often limit treatment options. Median overall survival in most studies post-JAKi demonstrate poor outcomes (14-28 months) among patients with MF. Consequently, there is a considerable need in identifying new therapeutic targets beyond JAK-STAT inhibition. One potential cancer target is CD123, aberrantly expressed on leukemia stem cells and aberrant/malignant microenvironmental plasmacytoid dendritic cells (pDC) in certain myeloid cancers including MF. Tagraxofusp (TAG), a CD123-targeted therapy FDA-approved for patients with blastic plasmacytoid dendritic cell neoplasm, a pDC-derived malignancy, has demonstrated preclinical proof-of-concept in MF. We now report the updated results of an ongoing study of TAG monotherapy in patients with relapsed/refractory MF, or who were unable to tolerate currently approved JAKi. (NCT02268253) Experimental Design: A multicenter Phase 1/2 trial with TAG administered as a daily IV infusion at 7, 9, or 12 mcg/kg on days 1-3 every 21 days (cycle 1-4), 28 days (cycles 5-7), and 42 days (cycles 8+) in stage 1, and 12 mcg/kg every 21 days (C1-4), 28 days (C5+) in the currently ongoing stage 2. Results: Thirty-five patients (pts) with a median age 69 years (range: 54-87) have been treated thus far: 26% had baseline monocytosis and 69% had baseline thrombocytopenia, which impacts optimal dosing of JAKi, including 37% with platelets &lt;50x109/L including 7 pts with platelets ≤20; 75% had baseline palpable splenomegaly. Baseline genomic analysis in 35 pts revealed: JAK2 V617F (n=21); CALR (n=3); MPL (n=2); 7 of 21 pts who had comprehensive NGS, had an ASXL1 mutation. Most common treatment-related adverse events (incidence ≥15%) include hypoalbuminemia (23%), headache (17%), and elevated alanine aminotransferase (17%). Notably, capillary leak syndrome (CLS) was reported in 3 pts (1 was grade 4). Twenty-one pts (60%) achieved stable disease (SD) by IWG-MRT revised 2013 criteria, including 4 who had substantial clinical benefits; SD was noted in 7 of 9 (78%) with monocytosis, 7 of 13 (54%) with baseline platelets ≤50x109/L, including 3 of 7 (43%) with baseline platelets ≤20x109/L, and 2 of 3 (67%) pts with accelerated phase. At week 24, spleen responses by palpation were observed in 10 (45%), including 2 with &gt;50% spleen reduction; 12 of 26 (46%) had symptom burden reduction, including 3 pts who met the IWG-MRT criteria. There have been three deaths, all deemed to be unrelated to study drug, occurring in cycles 1, 6, 13, respectively. The median overall survival of our cohort was 31 months (range: 0.6-42 months). Conclusions: Interim results demonstrate clinical efficacy and safety of TAG monotherapy in JAKi relapse/refractory/intolerant MF patients, including those associated with recognized poor-risk biological and clinical features, such as monocytosis. Some patients have experienced clinical benefit, including reduction in splenomegaly and improvement in quality of life and enrollment continues. Disclosures Pemmaraju: Celgene: Honoraria; DAVA Oncology: Honoraria; Roche Diagnostics: Honoraria; Blueprint Medicines: Honoraria; AbbVie: Honoraria, Research Funding; MustangBio: Honoraria; SagerStrong Foundation: Other: Grant Support; Pacylex Pharmaceuticals: Consultancy; Novartis: Honoraria, Research Funding; LFB Biotechnologies: Honoraria; Stemline Therapeutics: Honoraria, Research Funding; Plexxikon: Research Funding; Cellectis: Research Funding; Incyte Corporation: Honoraria; Affymetrix: Other: Grant Support, Research Funding; Daiichi Sankyo: Research Funding; Samus Therapeutics: Research Funding. Gupta:Sierra Oncology: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol MyersSquibb: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Consultancy; Incyte: Honoraria, Research Funding. Ali:Incyte Corporation: Consultancy. Yacoub:Hylapharm: Current equity holder in private company; Incyte: Speakers Bureau; Agios: Honoraria, Speakers Bureau; Novartis: Speakers Bureau; Roche: Other: Support of parent study and funding of editorial support; Dynavax: Current equity holder in publicly-traded company; Ardelyx: Current equity holder in publicly-traded company; Cara Therapeutics: Current equity holder in publicly-traded company. Wang:PTC Therapeutics: Consultancy; Stemline: Speakers Bureau; Macrogenics: Consultancy; Astellas: Consultancy; Genentech: Consultancy; Pfizer: Speakers Bureau; Abbvie: Consultancy; Jazz Pharmaceuticals: Consultancy; Bristol Meyers Squibb (Celgene): Consultancy. Lee:Roche Molecular Systems: Consultancy; Jazz: Consultancy; AstraZeneca: Consultancy; Helsinn: Other: Member -DSMB; BMS: Consultancy. Schiller:Pfizer: Current equity holder in publicly-traded company, Research Funding; Regimmune: Research Funding; Samus: Research Funding; Sangamo: Research Funding; Tolero: Research Funding; Trovagene: Research Funding; Kaiser Permanente: Consultancy; Johnson & Johnson: Current equity holder in publicly-traded company; Jazz Pharmaceuticals: Research Funding; Geron: Research Funding; Genentech-Roche: Research Funding; Gamida: Research Funding; FujiFilm: Research Funding; Forma: Research Funding; Bristol-Myers Squibb: Current equity holder in publicly-traded company, Research Funding; DeltaFly: Research Funding; Deciphera: Research Funding; Daiichi Sankyo: Research Funding; Cyclacel: Research Funding; Constellation: Research Funding; Celator: Research Funding; Astellas Pharma: Honoraria, Research Funding; Ariad: Research Funding; Actinium: Research Funding; Abbvie: Research Funding; Stemline: Speakers Bureau; Gilead: Speakers Bureau; Agios: Consultancy, Research Funding, Speakers Bureau; Sanofi: Speakers Bureau; Amgen: Consultancy, Current equity holder in publicly-traded company, Research Funding, Speakers Bureau; AstraZeneca: Consultancy; Incyte: Consultancy, Research Funding, Speakers Bureau; Novartis: Consultancy, Research Funding; Ono Pharma: Consultancy; Celgene: Research Funding, Speakers Bureau; Karyopharm: Research Funding; Kite Pharma: Research Funding; Mateon: Research Funding; MedImmune: Research Funding; Onconova: Research Funding. Brooks:Stemline: Current Employment. Rupprecht:Stemline: Current Employment. Talpaz:Takeda: Research Funding; IMAGO: Consultancy; Constellation Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; BMS: Membership on an entity's Board of Directors or advisory committees; Novartis: Research Funding. Mughal:Stemline: Current Employment. Verstovsek:PharmaEssentia: Research Funding; AstraZeneca: Research Funding; ItalPharma: Research Funding; Incyte Corporation: Consultancy, Research Funding; Gilead: Research Funding; Promedior: Research Funding; CTI Biopharma Corp: Research Funding; Genentech: Research Funding; Blueprint Medicines Corp: Research Funding; Novartis: Consultancy, Research Funding; Sierra Oncology: Consultancy, Research Funding; Roche: Research Funding; NS Pharma: Research Funding; Celgene: Consultancy, Research Funding; Protagonist Therapeutics: Research Funding.