Resolution Of Splenomegaly Research Articles

Efficacy of the Allosteric MEK Inhibitor Trametinib in Relapsed and Refractory Juvenile Myelomonocytic Leukemia: A Report from the Children's Oncology Group

Background: Juvenile myelomonocytic leukemia (JMML) is an aggressive myeloproliferative neoplasm of infants and toddlers. Upfront therapies typically include high-dose cytarabine or azacitidine, but the only definitive treatment is hematopoietic stem cell transplantation (HSCT). While HSCT cures ~50% of patients, the prognosis is dismal for those who relapse. In the absence of a second HSCT, patients who relapse have a 2-year overall survival of ~10%. JMML is initiated by germline and somatic driver mutations in NF1, KRAS, NRAS, PTPN11, and CBL. These mutations converge on Ras signaling, leading to elevated levels of active Ras-GTP in specific cell lineages. Genetically engineered mouse (GEM) models accurately model key molecular, biologic, and biochemical features of JMML. Preclinical trials of the allosteric MEK inhibitors in Kras and Nf1 mutant mice demonstrated dramatic phenotypic responses with reduction in white blood cell counts, resolution of splenomegaly, and reversion to normal erythropoiesis. Based on the promising efficacy signal in GEM models, we evaluated trametinib, an orally bioavailable allosteric inhibitor of MEK1/2, in a prospective clinical trial in children with relapsed or refractory JMML to determine the overall response rate to trametinib. Results: Ten infants and children with JMML (median age 23.6 months) were enrolled and all were evaluable for safety and efficacy. Patients received age-adjusted dosing of trametinib for 28-day cycles and could remain on study for up to 12 cycles in the absence of disease progression or toxicity. A clonal Ras pathway mutation was confirmed in the blood and/or bone marrow of all patients. The objective response rate was 50% (two complete and three partial clinical responses). Four patients proceeded to HSCT after receiving protocol therapy and remain alive in complete remission with undetectable levels of the Ras pathway mutation identified at enrollment. Three additional patients completed 12 cycles of trametinib and continue to receive off-protocol therapy 6-24 months later with no change in the variant allele frequency of the underlying Ras pathway mutation. The remaining three patients had progressive disease with two demonstrating molecular evolution by the end of cycle 2. Paired pre- and post-trametinib RNASeq and proteomic analyses confirmed on-target biochemical effects of trametinib with down-regulation of both Ras/MAPK pathway related gene expression and MEK1/2 kinase activity, respectively. To gain deeper insight into how trametinib might affect distinct populations of hematopoietic cells, we generated single cell RNASeq data before and after treatment. The most prominent finding was a reduction in the proportions of classical and non-classical monocytes and broad downregulation of immune-related pathways in all cell populations. However, the downregulation of MAPK signaling genes was confined to specific cell types including, macrophages, classical monocytes, and granulocyte-monocyte progenitors, which uniquely displayed downregulated KRAS-related signatures following treatment. High DNA methylation and the presence of >1 mutation at enrollment correlated with lack of response to trametinib. Conclusions: We conducted an open label, phase 2 trial of trametinib in children with relapsed or refractory JMML. This is the first completed study of a MEK inhibitor in any hematologic malignancy in children. The trial met its primary objective and demonstrated a 50% objective response rate with 70% of patients bridging to a successful HSCT or completing the maximum 12 cycles permitted on study. The three patients who completed 12 cycles continue to receive trametinib off study for as long as 2 years. Although limited by a small number of patients, the long-term survival, and correlative molecular analyses from this trial raise provocative questions about whether certain patients with JMML might be spared the long-term adverse health risks of genotoxic HSCT conditioning regimens based on favorable molecular characteristics at diagnosis. This hypothesis will now be tested in a national, risk-stratified therapeutic trial (NCT05849662) of trametinib in combination with azacitidine in newly diagnosed patients. The authors would like to acknowledge funding and support from: NCTN Operations Center Grant (U10CA180886), NCTN Statistics & Data Center Grant (U10CA180899), and the St. Baldrick's Foundation.

LNK/SH2B3 As a Novel Driver in Juvenile Myelomonocytic Leukemia

Introduction Juvenile myelomonocytic leukemia (JMML) is a rare and aggressive myelodysplastic/myeloproliferative disorder in toddlers. Ninety-five percent of patients have mutations detected in the Ras/MAPK signaling pathway including CBL, KRAS, NF1, NRAS, RRAS, RRAS2, and PTPN11. Oncogenic fusion proteins leading to hyperactive Ras signaling and other mutations in genes encoding for proteins upstream the Ras pathway have also been described. One of these upstream proteins is LNK which is encoded by SH2B3. Loss of function mutations in SH2B3 result in abnormal proliferation of hematopoietic cells due to cytokine hypersensitivity and activation of JAK/STAT signaling. Mutations in SH2B3 have been detected in a variety of hematologic malignancies, specifically in myeloproliferative neoplasms in adults. We previously identified secondary mutations in SH2B3 in JMML. Here we report a case series of four JMML patients with initiating mutations in SH2B3. We also show that SH2B3 mutant induced pluripotent stem cell (iPSC)-derived JMML like hematopoietic progenitor cells (HPC) are sensitive to JAK inhibitors including ruxolitinib. Patients and Methods Genomic DNA from peripheral blood, bone marrow or buccal swabs was extracted using standard protocols. DNA samples were sequenced using a custom amplicon-based targeted sequencing approach. Ficoll-purified mononuclear cells from bone marrow of JMML patients and control samples were reprogrammed by using Sendai virus expressing doxycycline-regulated OCT4, KLF4, MYC, and SOX2. Control and JMML iPSCs were differentiated to HPCs by culturing in serum-free media with sequential combinations of growth factors to support multipotent hematopoietic progenitor formation. The half-maximal inhibitory concentration (IC50) for each kinase inhibitor was determined by performing Cell Titer Glo assays (Promega). Results Clinical characteristics of patients with SH2B3 mutant JMML described in this study are highlighted in Table 1. iPSC-derived JMML-like HPCs with different mutational backgrounds were analyzed in cell proliferation assays after exposure to multiple different JAK inhibitors (ruxolitinib, momelotinib, tofacitinib). HPCs with alterations in SH2B3 were more sensitive to chemical JAK inhibition compared to HPCs not harboring mutations in SH2B3. This finding was observed for all JAK inhibitors but was most prominent with ruxolitinib (Figure 1). Patient 3 received ruxolitinib monotherapy after being refractory to 6-mercaptopurine. Treatment resulted in resolution of splenomegaly but no reduction in the variant allele frequency of SH2B3. The patient is now alive more than one year after hematopoietic stem cell transplantation (HSCT). Discussion In a previous study of 100 patients with JMML we first identified seven patients with secondary SH2B3 mutations. Here, we report four additional patients with JMML that appear to be driven by initiating mutations in SH2B3 (Table 1). The mutations identified here result in a truncated protein (patient 1, 3 and 4) or affect the SH2 domain (patient 2). Interestingly, copy neutral loss of heterozygosity of SH2B3 in patient 1, also known as uniparental isodisomy, is a mechanism that has been observed in other genes (e.g. CBL and NF1) in JMML. Since in vitro data showed that loss of LNK results in increased JAK/STAT signaling, we hypothesized that this cohort of patients may benefit from JAK inhibitor therapy. Our data from iPSC-derived JMML like HPCs shows, that those cells with an additional SH2B3 mutation are more sensitive to JAK inhibitors, specifically ruxolitinib, a JAK1/2 inhibitor that is already approved or under investigation in multiple clinical trials. In summary, we expand the list of initiating mutations in JMML to include SH2B3 and raise the possibility of targeting the JAK pathway in these patients. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Successful Retreatment With Venetoclax in a Patient With Chronic Lymphocytic Leukemia.

Successful Retreatment With Venetoclax in a Patient With Chronic Lymphocytic Leukemia.

Real-World Investigation of Spleen, Symptom, and Hematologic Response in Patients with Myelofibrosis Treated with First-Line Ruxolitinib

Introduction: Relief of symptoms and splenomegaly are important treatment goals for all patients with myelofibrosis (MF). Until 2019, ruxolitinib (RUX) was the only FDA-approved therapy for the treatment of intermediate- or high-risk MF. This study sought to explore real-world treatment patterns and clinical outcomes, including spleen response, hematologic response, and patient symptomology during first-line (1L) RUX therapy to describe the unmet need in RUX-treated patients with MF. Methods: A retrospective, multisite (US community oncology practices) medical chart review of patients with MF who initiated 1L RUX between January 2015 and December 2017 was undertaken. Patient demographic and clinical characteristics at initiation of RUX, and RUX dosing and dose modifications were abstracted. In addition, at the initiation of RUX and every patient visit during the first 6 months of therapy, physicians abstracted data on spleen size, symptom burden, and hematologic parameters. We assessed the rate of dose modifications (decrease or increase) during the first 6 months of therapy and subsequently compared patients who dose modified to those who did not (stable dose). Univariate comparisons between cohorts of baseline characteristics were performed (chi-square and t-tests). Time to treatment discontinuation was described. The proportion of patients with spleen length reduction, palpable spleen resolution, resolution of ≥ 1 baseline symptom, and platelet decrease to < 100 × 109/L at 6 months following RUX initiation was described and compared between dose-modified and stable-dose cohorts. The Kaplan-Meier method was used to estimate these proportions; patients were censored on their date of treatment discontinuation if the outcome had not occurred. Results: Data for 152 patients were collected from 37 different sites across the USA (South 43.2%, Northeast 21.6%, Midwest 18.9%, West 16.2%). Mean follow-up was 26 months from initiation of 1L RUX; 29% of patients were deceased at the time of data abstraction. Overall, 69 patients (45.4%) were not initiated on the recommended dose of RUX based on their platelet count according to US package insert. Forty-five patients (29.6%) were dose modified during the first 6 months of therapy including 39 with dose decreases and 7 with dose increases (1 patient had both a decrease and increase). Physicians reported the most common reason (76.9%) for dose reduction was a hemoglobin level of 8-10 g/dL or platelet count 50-75 × 109/L. The most common reason (57.1%) for dose increase was provider decision to start on a low dose and titrate to a therapeutic dose. Mean age at diagnosis was significantly higher in the dose-modified subgroup (70 vs 62 years, P < 0.01) compared to the stable-dose subgroup, while platelets at the time of RUX initiation were significantly lower (246 vs 326 × 109 /L, P = 0.03); no other baseline factors were associated with dose modification during the study period. At the time of chart data abstraction, 57.0% of stable-dose and 66.7% of dose-modified patients had discontinued RUX. Among stable-dose and dose-modified patients who had discontinued RUX, the median time to discontinuation was 10.7 and 10.0 months, respectively, while duration of treatment for patients still receiving RUX was 26.4 and 28.6 months, respectively. At 6 months, while not statistically significant, a lower proportion of patients in the dose-modified cohort achieved spleen length reduction by palpation (57.9% vs 65.6%; P = 0.710) and resolution of splenomegaly (39.1% vs 49.3%; P = 0.090) (Figure, panel A). A lower proportion of patients in the dose-modified cohort had resolution of ≥ 1 baseline symptom (19.9% vs 39.1%; P = 0.003) (Figure, panel B). Among patients with ≥ 100 × 109/L platelets at baseline, a significantly higher proportion of patients in the dose-modified cohort had platelets decrease to < 100 × 109/L during 1L RUX treatment (66.0% vs 16.7%; P < 0.001) (Figure, panel C). Conclusions: Dose modifications occurred in nearly one third of 1L RUX-treated patients, with the majority requiring a dose decrease. Patients with dose modifications were less likely to have improved splenomegaly or symptom burden and experienced significantly lower platelet counts than those who maintained a stable dose of RUX during the first 6 months of therapy. These findings identify a population of RUX-treated patients with a significant need for alternative MF treatments. Figure Disclosures Kish: Cardinal Health: Current Employment, Current equity holder in publicly-traded company. Kee:Bristol Myers Squibb: Current Employment. Abraham:BMS: Current Employment, Current equity holder in publicly-traded company. Copher:Bristol Myers Squibb: Current Employment. Miller:Cardinal Health: Current Employment. Gerds:Imago Biosciences: Research Funding; Roche/Genentech: Research Funding; CTI Biopharma: Consultancy, Research Funding; Pfizer: Research Funding; Apexx Oncology: Consultancy; AstraZeneca/MedImmune: Consultancy; Sierra Oncology: Research Funding; Incyte Corporation: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Gilead Sciences: Research Funding.

HARMONY: An Open-Label, Multicenter, 2-Arm, Dose-Finding, Phase 1b Study of the Combination of Ruxolitinib and Buparlisib (BKM120) in Patients with Myelofibrosis (MF)

BACKGROUND: Ruxolitinib (RUX) is a potent JAK1/JAK2 inhibitor that has demonstrated improvements in splenomegaly, MF-related symptoms, and quality of life measures and prolonged survival in 2 phase 3 studies. JAK signaling can activate the PI3K/mTOR pathway, and constitutive PI3K activation has been implicated in numerous cancers. Preclinical and early clinical results indicate benefit with inhibition of PI3K in MF. Buparlisib is a pan-PI3K inhibitor with specific and potent activity against class I PI3Ks. The aims of HARMONY are to evaluate the safety of co-administration of RUX and buparlisib in patients (pts) with MF and determine a recommended phase 2 dose (RP2D).METHODS: This is a dose-finding, phase 1b study (NCT01730248) of RUX plus buparlisib in intermediate- or high-risk MF pts. Pts must have palpable splenomegaly ≥ 5 cm below the costal margin and MF symptoms. There are 2 treatment groups (JAK inhibitor–naive pts [arm A] and pts not benefiting from prior JAK inhibition [arm B]) and 2 study phases (dose escalation and expansion). Dose escalation is guided by a Bayesian logistic regression model with overdose control and depends on dose-limiting toxicities in cycle 1 and other safety findings. Each dose level consists of ≥ 3 evaluable pts; the 5 dose levels are (RUX [mg bid]/buparlisib [mg qd]) 10/60, 15/60, 15/80, 20/80, 20/100. 9 evaluable pts are required at the final dose level to determine an RP2D and proceed to the expansion phase; 10 additional pts per arm will be treated at the RP2D. PK of RUX was assessed by LC-MS/MS on day 1 after the first dose of RUX and on days 2 and 8 when administered in combination with buparlisib.RESULTS: To date, 33 pts (arm A, n = 20; arm B, n = 13) have been treated in the dose-escalation phase. Baseline characteristics were (arm A and arm B) median age, 64 y (range, 48-79 y; 45% ≥ 65 y) and 61 y (53-74 y; 31% ≥ 65 y); male, 50% and 62%. RP2D was selected based on tolerability in the investigated dose levels, with additional confirmation from dose-selection recommendations derived through a Bayesian model.Currently, RUX 15 mg bid/buparlisib 60 mg qd was determined as the RP2D in both arms; the study is proceeding into the expansion phase.At data cutoff (April 1, 2014), 15 (75%) and 8 (62%) pts were ongoing in arm A and arm B with a median exposure of 11.3 wk (range, 2.3-48.4 wk) and 19.0 wk (range, 0.6-50.9 wk), respectively. The primary reasons for discontinuation included lack of efficacy (10%) in arm A and AEs (15%) in arm B; all other reasons were in 1 pt each. There was 1 death (arm A) from duodenal ulcers/perforation, assessed as not related to study drugs by the investigator.Despite the short follow-up, a ≥ 50% reduction from baseline in palpable spleen length was achieved by 70% and 54% of pts in arms A and B; 7 pts had a resolution of splenomegaly (6 in arm A; 1 in arm B). All pts with prior JAK inhibitor treatment, including 5 who had no previous spleen length reductions, had reductions with the combination.Hematologic AEs included anemia (all grade [grade 3/4]: arm A, 30% [15%]; arm B, 31% [23%]) and thrombocytopenia (40% [10%]; 62% [39%]). Nonhematologic AEs were primarily grade 1/2 (Table). Overall, 20% and 23% of pts experienced serious AEs; these occurred in 1 pt each, with the exception of pyrexia (n = 2).PK parameters of RUX were comparable when administered alone or in combination with buparlisib, suggesting a lack of impact of buparlisib on RUX PK.CONCLUSIONS: The combination of RUX and buparlisib was well tolerated, with early signs indicating promising efficacy even in pts who have previously failed JAKi; preliminary RP2D was assessed as RUX 15 mg bid/buparlisib 60 mg qd for both arms. Updated efficacy and safety for the dose-escalation phase will be presented (July 1, 2014 data cutoff).TableNonhematologic AEs in ≥ 2 Pts in Either ArmPts, %Arm A n = 20Arm B n = 13All GradeGrade 3/4All GradeGrade 3/4Abdominal distension15080Abdominal pain100150Abdominal pain lower00150Abdominal pain upper50150Diarrhea100468Dyspepsia10000Nausea100310Stomatitis15588Vomiting50150Asthenia00310Fatigue100230General health deterioration00150Edema peripheral10000Pyrexia1502315Nasopharyngitis150150Decreased appetite50468Hyperglycemia15500Hyperkalemia55150Arthralgia20580Pain in extremity10080Dizziness50230Anxiety205150Confusional state10080Depressed mood00158Depression00158Insomnia50150Epistaxis50150Hyperhidrosis00310Night sweats00230Hypertension10500 DisclosuresDurrant:Novartis: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding. Off Label Use: Yes; Ruxolitinib is a kinase inhibitor indicated for treatment of patients with intermediate or high-risk myelofibrosis, including primary myelofibrosis, post-polycythemia vera myelofibrosis and post-essential thrombocythemia myelofibrosis. Buparlisib is an investigational agent. Koren-Michowitz:Novartis: Honoraria, Research Funding. Lavie:Novartis: Membership on an entity’s Board of Directors or advisory committees. Martinez-Lopez:Novartis: Research Funding; BMS: Honoraria; Celgene: Honoraria. Vannucchi:Novartis Pharmaceuticals Corporation: Consultancy, Honoraria, Research Funding. Stalbovskaya:Novartis: Employment, Equity Ownership. Atienza:Novartis: Employment. Iommazzo:Novartis: Employment. Gopalakrishna:Novartis: Employment. Gisslinger:AOP ORPHA: Consultancy, Honoraria, Research Funding, Speakers Bureau; Novartis: Honoraria, Research Funding, Speakers Bureau; Celgene: Consultancy, Honoraria, Research Funding, Speakers Bureau; Janssen Cilag: Honoraria, Speakers Bureau; Geron: Consultancy; Sanofi Aventis: Consultancy.

RESPONSE 2: A phase 3b study evaluating the efficacy and safety of ruxolitinib in patients with hydroxyurea (HU)-resistant/intolerant polycythemia vera (PV) versus best available therapy (BAT).

TPS7128^ Background: PV is a myeloproliferative neoplasm characterized by clonal stem cell proliferation, hyperviscous blood, significant morbidity, and reduced life span. Advanced PV results in splenomegaly, severe constitutional symptoms, and possible evolution to myelofibrosis and acute myeloid leukemia (AML). Nearly all patients (pts) have a mutation in JAK2, and > 95% have the JAK2 V617F allele. HU is the myelosuppressive agent of choice in high-risk pts, but it often loses efficacy over time and may cause unacceptable skin toxicities. Therapeutic options in the case of HU resistance are limited, and survival is significantly reduced. A phase 2 study in HU-resistant/-intolerant PV pts showed that ruxolitinib, a potent and selective JAK1/JAK2 inhibitor, was well tolerated and achieved rapid and durable clinical responses, including hematocrit (Hct) normalization, phlebotomy independence, resolution of splenomegaly, and improvements in symptoms (Verstovsek et al, Cancer, 2013). RESPONSE, a phase 3 tria...

Baseline Characteristics and Symptom Burden in RESPONSE: A Randomized, Open-Label, Phase 3 Study of Ruxolitinib In Polycythemia Vera Patients Resistant to or Intolerant of Hydroxyurea

Abstract Background Polycythemia vera (PV) is the most common of the myeloproliferative neoplasms and is characterized by elevated hematocrit requiring phlebotomy, splenomegaly, a variety of symptoms and increased thrombotic risk. Ruxolitinib, a JAK1/JAK2 inhibitor, was well tolerated and achieved rapid and durable clinical responses in a phase 2 study of patients (pts) with PV who were resistant to or intolerant of hydroxyurea (HU). Pts experienced phlebotomy independence, resolution of splenomegaly, and improvements in white blood cell (WBC) counts, platelet (PLT) counts, and disease-related symptoms. Here, we describe the baseline (BL) characteristics and symptom burden of pts in a phase 3 study of ruxolitinib in pts with PV who are resistant to or intolerant of HU. Methods RESPONSE is a randomized (1:1), open-label, phase 3 study (NCT01243944) comparing the efficacy and safety of ruxolitinib with best available therapy (BAT) in pts with PV who are resistant to or intolerant of HU (modified European LeukemiaNet criteria), have splenomegaly, and require phlebotomy for inadequate hematocrit (Hct) control. Fourteen disease-related symptoms were assessed on a scale of 0 (absent) to 10 (worst imaginable) using the modified Myeloproliferative Neoplasm Symptom Assessment Form (MPN-SAF). Blinded data are presented here. Results BL demographic data are available for the 222 enrolled pts (Table). Apart from HU, other common prior medications for PV included interferons (15%), PLT aggregation inhibitors (10%), alkylating agents (3.6%), alkyl sulfonates (3.2%), pyrimidine analogues (1.8%), and nitrosoureas (1.4%). The majority of pts (54.5%) had 1 phlebotomy within 12 weeks prior to screening; 23.9% had 2 and 17.1% had 3 or more phlebotomies. RESPONSE BL demographics are generally similar in terms of age (60 years vs 57-67); sex (66% male vs 58%-68%); Hct (44% vs 45%-48%); and platelets (419 x 109/L vs 320-429 x 109/L) to other PV studies including trials of givinostat (Finazzi BJH 2013) and AOP2014 (Gisslinger ASH 2012) and the ECLAP-PV (Marchioli JCO 2005) and CYTO-PV studies (Marchioli NEJM 2012). At the time of writing, BL symptom data from the MPN-SAF were available for 164 pts (Table). Pts in this study reported a similar symptom burden as PV pts from a large study of pts with MPNs (Emanuel JCO 2012; N = 1425; PV, n = 538), including similar mean scores for early satiety, abdominal discomfort, concentration problems, night sweats, itching, and tiredness/fatigue. In addition, prior therapy may have adversely affected BL symptom burden, as many of these symptoms (concentration problems, night sweats, fatigue) have been shown to be worsened by the use of conventional therapy to strictly control Hct (< 45%) and cardiovascular risk (Emanuel EHA 2013). BL MPN-SAF symptom data for all 222 pts will be presented. In addition, correlations between BL EORTC QLQ-C30 and MPN-SAF scores will be presented. Summary/Conclusions Demographic and BL symptom data from the RESPONSE study demonstrated that pts with HU refractory or intolerant PV have a significant disease burden that includes a variety of symptoms. These findings are consistent with those of Emanuel (JCO 2012), which showed that pts with PV have a significant symptom burden and a reduced quality of life. Pts with PV in the RESPONSE study are representative of those who have been studied in other clinical trials for the treatment of PV. Disclosures: Vannucchi: Novartis: Honoraria, Membership on an entity’s Board of Directors or advisory committees. Off Label Use: Ruxolitinib, a JAK1/JAK2 inhibitor, has been approved by the US Food and Drug Administration for the treatment of intermediate- or high-risk MF and by the European Commission and Health Canada for the treatment of disease-related splenomegaly or symptoms in adult patients with MF. Here, we describe the baseline (BL) characteristics and symptom burden of patients in a phase 3 study of ruxolitinib in patients with PV who are resistant to or intolerant of HU. Kiladjian:Novartis: Honoraria; Shire: Honoraria. Durrant:Novartis: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding; Sanofi: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding. Pane:Novartis: Consultancy, Honoraria; Shire: Honoraria. Harrison:Novartis: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding, Speakers Bureau; Sanofi: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Speakers Bureau; YM Bioscience: Honoraria, Membership on an entity’s Board of Directors or advisory committees; Celgene: Honoraria; Shire: Speakers Bureau; SBio: Honoraria, Membership on an entity’s Board of Directors or advisory committees; Gilead: Honoraria, Membership on an entity’s Board of Directors or advisory committees. He:Incyte: Employment. Leopold:Incyte: Employment, Stock options Other. Li:Novartis: Employment, Equity Ownership. Pirron:Novartis: Employment, Equity Ownership. Lawniczek:Novartis: Employment. Verstovsek:Incyte: Research Funding.

Megakariocytic Hypoplasia Due To TKIs In a CML Patient Can Be Overcome By TPO Receptor Agonist Eltrombopag

Background Patients who develop severe thrombocytopenia while treated with TK inhibitors may be forced to stop them, face a worse prognosis, and eventually require a treatment with a bone marrow transplant. Eltrombopag is a TPO receptor agonist that stimulates megakaryocytic proliferation. Case 62-year-old man presented in October 2008 with splenomegaly and leukocytosis. The bone marrow biopsy was diagnostic of CML. Imatinib was started at 400 mg daily resulting in hematological response and resolution of splenomegaly, but severe thrombocytopenia necessitated 50 % dose reduction. Thrombocytopenia was not responsive to Prednisone, and a trial of platelets transfusions with the standard dose of Imatinib had to be stopped because of thrombocytopenia below 10 K and the risk of bleeding – reducing the dose of the TKI was improving the platelet count. Treatment with Dasatinib and with Nilotinib also necessitated 50 % dose reductions because of thrombocytopenia. These reduced TKI dosing resulted in the best Quantitative RT-PCR for bcr/abl product reduction level at – 1.01. Bone marrow biopsy in December 2010 showed no morphologic evidence of CML, and no dysplasia; it was normocellular marrow with erythroid hyperplasia and megakaryocytic hypoplasia. Cytogenetic analysis and FISH showed presence of the Philadelphia chromosome rearrangement. The patient declined the treatment with a Bone marrow transplant. In April 2011 a TPO agonist Eltrombopag 50 mg daily was started, given on two weeks on two weeks off schedule. As platelets remained adequate since then, the Nilotinib was escalated to the full dose of 400 mg twice daily. The patient tolerated the treatment well. Results The patient required about half-a-year support with Eltrombopag; after that it was discontinued as the platelet count remained above 40 K. No dose reduction of Nilotinib was necessary. In January 2012 the patient reached the milestone of Complete Cytogentic Response with the level of bcr/abl transcript minus 2 or less, which continued to decrease and now the patient is achieving a Major Molecular Response. Conclusion Treatment of CML with Tyrosine Kinase Inhibitors – Imatinib, Dasatinib, or Nilotinib in our patient – can be complicated by severe thrombocytopenia. These patients’ next treatment option may be a Bone marrow transplant. Limited use of Eltrombopag can improve thrombocytopenia, and allow these patients to continue TKIs with attainment of the treatment milestons. Disclosures: Off Label Use: Eltrombopag. It is used in thrombocytopenia, in ITP. In this presentation it was used to treat thrombocytopenia secondary to Thyrosine Kinase Inhibitors in Chronic Myelogenous Leukemia.

Rapid Clearance Of JAK2 V617F Allele Burden In Patient With Advanced Polycythemia Vera (PV) During Combination Therapy With Ruxolitinib and Peg-Interferon Alpha-2a

BackgroundTreatment with pegylated interferon-alpha2 (IFN) is associated with complete hematologic remissions (CHR) in a large majority of patients with essential thrombocythemia (ET) and PV. In a subset of patients, IFN can induce major molecular remissions that can be sustained for up to 4 years after discontinuation of therapy. In hypercellular myelofibrosis (MF), IFN may also induce regression of bone marrow fibrosis. To this end, long-term IFN treatment with normalization of elevated blood counts is accompanied by a reduced risk of thrombosis and hemorrhage. When initiated at the early disease stage, IFN may have the greatest chance to induce “minimal residual disease” with a low JAK2 V617F allele burden. For these reasons, IFN is foreseen to be a cornerstone in the treatment of these neoplasms. Ruxolitinib (RUX) is a JAK1-2 inhibitor that is highly efficacious in alleviating hypermetabolic symptoms and enlarged spleens in patients with MF. Although the earliest reports suggested that RUX did not significantly lower JAK2 V617F mutational load, newer findings clearly show that in a subset of patients RUX may indeed profoundly decrease JAK2 V617F allele burden; these reductions could be even larger if treatment is instituted in early stages of MF or PV. Preliminary data show RUX to be highly efficacious in PV as well. With both drugs having potent antiproliferative and anti-inflammatory effects, combination therapy with IFN and RUX may potentially promote tumor regression in MPNs, as assessed by rapid induction of CHR, reduction in spleen size, and enhanced reduction of JAK2 V617F allele burden. Case reportA 55-year-old woman with PV diagnosed in the precursor stage of ET 12 years ago was referred for a second opinion due to intolerance of hydroxyurea (HU; monosymptomatic fever) and pegylated interferon-alpha2b (PEG-Intron; exanthema). The patient had suffered 2 episodes of transitory ischemic attack (TIA) since 2009, and therefore, permanent treatment with clopidogrel had been instituted. Several CT scans were normal. At the time of referral, the patient was receiving anagrelide and clopidogrel. The patient's hemoglobin was 11.9 g/dL, her leukocyte count was 21.9 x 109/L, and platelets were elevated at 526 x 109/L. CRP levels were normal. An abdominal ultrasound revealed a spleen length of 20 cm, causing intermittent pain and abdominal discomfort. Because of hypermetabolic symptoms, pronounced abdominal discomfort, and intolerance of PEG-Intron and HU, treatment with RUX was initiated at a dose of 20 mg twice daily. Within the first 3 days of RUX therapy, the patient experienced remarkable clinical improvement with resolution of severe fatigue, night sweats, abdominal pain, and pruritus, which had negatively impacted the patient's quality of life during the past 2 to 3 years. Four days after starting RUX, the patient experienced acute TIA-like symptoms with transient decrease of strength in the left arm and abnormal sensations in the left half of the tongue and neck. The symptoms were similar to those that the patient experienced during previous TIAs. The blood values disclosed a slight decrease in the leukocyte count (17.6 x 109/L) and an increase in the platelet count (573 x 109/L). A CT scan was normal. Consequently, RUX therapy was combined with PEG-IFN-alpha2a (Pegasys) at a very low dose of 45 µg every second week. After 1 month, a CHR was achieved (Figure 1), and after 2.5 months, an abdominal ultrasound showed a spleen length reduction from 20 to 13.8 cm. After 6 months, the spleen was no longer palpable. The patient had no need of phlebotomies during treatment with RUX and Pegasys. The combination therapy was exceedingly well tolerated without any side effects to either drug. Remarkably, despite an advanced PV stage, JAK2 V617F allele burden was rapidly lowered from 90% mutated alleles at referral to 59% at 6 months and 20% within 1 year (Figure 2). [Display omitted] ConclusionThis case report demonstrates for the first time that combination therapy with RUX and “low–low-dose” Pegasys is highly efficacious in rapidly reducing JAK2 V617F allele burden in concert with achieving CHR and resolution of splenomegaly. This observation warrants prospective trials of this combinatorial approach in patients with PV and hyperproliferative MF to assess whether combination therapy induces a more rapid decline in the JAK2 V617F allele burden than monotherapy with either drug. Disclosures:Hasselbalch:Novartis: Consultancy, Honoraria, Speakers Bureau. Off Label Use: Interferon-alpha2a is used routinely in Denmark for treatment of essential thrombocythemia polycythemia vera and in some myelofrbrosis patients , as well. Ruxolitinib is being used routinely in myelofibrosis patients on strict indications including hypermetabolic symptoms and abdominaldiscomfort due to large splenomegaly ln rare cases Ruxolitinib is being used in the transitional stage of PV towards myelofibrosis when other options are not available due to intolerance to eg. interferonlor hydroryurea.

Final results of a phase I study of idelalisib (GSE1101) a selective inhibitor of PI3Kδ, in patients with relapsed or refractory CLL.

7003 Background: Signals through PI3K-delta regulate activation, proliferation and survival of B cells, critically influence homing and retention of B cells in lymphoid tissues, and are hyperactive in many BEcell malignancies. Idelalisib (GS-1101) is a first-in-class, selective, oral inhibitor of PI3Kδ that reduces proliferation, enhances apoptosis, and inhibits homing and retention of malignant B cells. Methods: Pts with relapsed/refractory CLL were treated continuously with single-agent oral idelalisib from 50E350 mg/dose (QD or BID). Response evaluated by investigators per Hallek (2008) and Cheson (2012). Results: 54 pts (9F/45M) median (range) age 63 (37E82) years enrolled with: bulky lymphadenopathy (80%), refractory disease (70%), extensive prior therapies (median: 5, range: 2E14), unmutated IgHV (91%), del17p and/or TP53 mutation (24%), del11q (28%), NOTCH1 mutation (17%). The median (range) exposure was 9 (0E41+) months. 25 (46%) pts completed the primary study, 23 (43%) enrolled into an extension study. ORR was 30/54 (56%, 2 CR, 28 PR). Of the 28 PR, 22 met Hallek (2008) and 6 met PR with lymphocytosis Cheson (2012). 44/54 (81%) showed a lymph node response (≥50% reduction in the nodal SPD). 21/54 were SD and 3/54 NE. The median (range) time to first response was 1.9 (0.9-12.9) months. Median PFS was 17 months and median DOR was 18 months. Idelalisib treatment resulted in resolution of splenomegaly (14/20, 70%) and normalization of cytopenias: anemia (17/25, 68%); thrombocytopenia (27/34 79%), neutropenia (15/15, 100%). Most common AEs independent of causality (any Grade/≥Gr 3) included fatigue (31%/2%), diarrhea (30%/6%), pyrexia (30%/4%), rash (22%/0%), upper respiratory tract infection (22%/0%), pneumonia (20%/19%). 2% of pts had ≥Gr 3 ALT/AST elevation. 15% of pts discontinued due to AEs, 7% potentially treatment-related. There were no dose-limiting toxicities. Conclusions: Idelalisib shows substantial clinical activity and a favorable safety profile in heavily pretreated, refractory and highErisk pts with CLL. Phase 3 trials with idelalisib in combination with rituximab or bendamustine/rituximab are ongoing. Clinical trial information: NCT01539512, NCT01569295.

Refractory Anemia with Ring Sideroblasts Associated with Marked Thrombocytosis Complicated by Massive Splenomegaly Treated with Lenalidomide Resulting in Resolution of Splenomegaly but Severe and Prolonged Pancytopenia

Refractory anemia with ring sideroblasts associated with marked thrombocytosis (RARS-T) is a hematological malignancy that combines features of both a myeloproliferative and myelodysplastic disorder. There have been recent reports of the successful treatment of anemia in 2 patients with RARS-T with lenalidomide. Here we report the successful treatment of massive splenomegaly in a patient with a long history of RARS-T resulting in complete resolution of splenomegaly, but with prolonged severe cytopenias. We also report the acquisition of the t(3;12)(q26;p13) translocation previously described in cases of myelodysplasia and the potential for transformation to myelofibrosis.

Doxycycline-induced Sinusoidal Obstruction Syndrome: A Case Report

Purpose: Sinusoidal obstruction syndrome (SOS), formerly known as venoocclusive disease, was first described with pyrrolizidine alkaloids, a compound found in certain herbal tea and spoiled wheat. In northern countries, chemotherapy, especially for induction of hematopoietic stem cell transplantation, is now the leading cause. Other etiologies have been reported such as high-dose abdominal radiotherapy, azathioprine and cyclophosphamide. We present here the case of a 48-year-old healthy man who was referred to our center for sudden onset of abdominal distension. The patient first noticed his symptoms just after completion of a 14-day doxycycline treatment for Q fever. At that time, his regular medication only included a benzodiazepine and tadalafil. No other risk factor for hepatopathy was retrieved except a daily alcohol intake of 55g for the last 20 years. The patient denied any natural medicine or drug use and there was no traveling history in the last year. Large hepatomegaly and ascites were confirmed on physical examination. Initial laboratory results included: ALP 340 U/L, ALT 32 U/L, AST 57 U/L, bilirubin 15 umol/L, albumin 31 g/L, INR 1.2, CRP 42. Whole traditional blood work-up for a specific cause of liver disease was negative and paracentesis showed a transudative gradient (SAAG = 17) resulting from portal hypertension. Abdominal CT scan demonstrated a 20-cm heterogeneous liver with normal caudate lobe, large ascites and a 14.5-cm spleen. Doppler ultrasound and MRI showed no suprahepatic veins obstruction. Upper endoscopy confirmed small esophageal varices and subtle hypertensive gastropathy. A percutaneous liver biopsy concluded to a venoocclusive disease caused by a drug reaction. Another pathologist from an expert liver center confirmed this diagnosis. Small dose diuretics were given to the patient, but no other specific treatment was instituted. Five months later, the patient is doing well with complete resolution of ascites and normalisation of hepatic blood work-up. Liver is no more palpable. A recent ultrasound showed regression of hepatomegaly with a persistently heterogeneous liver and resolution of splenomegaly and ascites. SOS is a very uncommon disorder secondary to toxic injury to sinusoidal endothelial cells. The patient's alcohol intake might have predisposed him to toxicity with doxycycline. This antibiotic has never been shown to cause SOS. However, no other agent could be incriminated in this case and the temporal relationship between the drug and the symptoms supports the causality. To our knowledge, this is the first case reported with doxycycline.

RESPONSE: A randomized, open-label, phase III study of ruxolitinib in polycythemia vera (PV) patients resistant to or intolerant of hydroxyurea (HU).

TPS6643^ Background: PV is a myeloproliferative neoplasm characterized by clonal stem cell proliferation, significant morbidity, shortened life span and possible evolution to myelofibrosis and acute myeloid leukemia. Splenomegaly, debilitating constitutional symptoms, and frequent phlebotomy requirements are common in advanced disease. HU, an established first-line agent for cytoreduction, can be associated with cytopenias, aphthous and leg ulcers, and other side effects. Control of hematocrit is not always achieved with HU, and many patients are either intolerant of or become resistant to HU. JAK2 plays a key role in the pathophysiology of PV; nearly 100% of patients harbor either the JAK2V617F or JAK2 exon 12 mutations. In a phase 2 study in HU-resistant or -intolerant PV patients, ruxolitinib, a potent and selective inhibitor of JAK1/JAK2, was well tolerated and achieved rapid and durable clinical responses, including phlebotomy independence, resolution of splenomegaly, and improvements in white blood cell (WBC) and platelet (PLT) counts and disease-related symptoms. Methods: RESPONSE is a randomized (1:1), open-label, global phase 3 study (NCT01243944) designed to compare the safety and efficacy of ruxolitinib with best available therapy (BAT) in adult patients with PV who are resistant to or intolerant of HU (modified European Leukemia Net criteria) and require phlebotomy because of inadequate hematocrit control. Inclusion criteria have been amended to include patients who exhibit palpable splenomegaly with an MRI-confirmed volume of ≥ 450 cm3 (ie, approximately 2.5 x median normal volume; instead of ≥ 5 cm by palpation) and PLT > 100 x109/L; the requirement for either elevated WBC (> 15 x109/L) or PLT count (> 600 x109/L) was removed. The primary efficacy endpoint is the achievement of both phlebotomy independence and a ≥ 35% reduction in spleen volume after 32 weeks of treatment. Patients will be treated for 80 weeks to assess safety and durability of response. Patients randomized to BAT may be eligible to cross over to receive ruxolitinib after week 32. Enrollment is planned for 145 investigational sites (134 currently open), with a target of 200 patients.

Phase 2 study of cladribine followed by rituximab in patients with hairy cell leukemia

AbstractWe conducted this study to determine the feasibility and safety of cladribine followed by rituximab in patients with hairy cell leukemia including the vari-ant form (HCLv). Cladribine 5.6 mg/m2 given IV over 2 hours daily for 5 days was followed ∼ 1 month later with rituximab 375 mg/m2 IV weekly for 8 weeks. Responses were recorded and BM minimal residual disease (MRD) was evaluated after the completion of rituximab. Thirty-six patients have been treated including 5 with HCLv. Median age was 57 years (range, 37-89). All patients (100%) have achieved complete response (CR), defined as presence of no hairy cells in BM and blood with normalization of counts (absolute neutrophil count [ANC]> 1.5 × 109/L, hemoglobin [Hgb] > 12.0 g/dL, platelets [PLT] > 100 × 109/L), as well as resolution of splenomegaly. There were no grade 3 or 4 nonhematologic adverse events directly related to the treatment. Only 1 patient (with HCLv) has relapsed; median CR duration has not been reached (range,1+-63+ months). Three patients with HCLv died including 1 with relapsed disease and 2 from unrelated malignancies. Median survival duration has not been reached (range, 2+-64+ months). Treatment with clad-ribine followed by rituximab is effective tk;4and may increase CR rate. This study was registered at www.clinicaltrials.gov as NCT00412594.

RESPONSE: A randomized, open label, phase III study of INC424 in polycythemia vera (PV) patients resistant to or intolerant of hydroxyurea (HU).

TPS203 Background: PV is a myeloproliferative neoplasm characterized by clonal stem cell proliferation causing increased red cell mass, blood hyperviscosity, significant morbidity, shortened lifespan and possible evolution to acute myeloid leukemia. Splenomegaly, debilitating symptoms, leukocytosis, and thrombocytosis are common in advanced disease. HU, an established first-line agent for cytoreduction, can be associated with cytopenias, aphthous and leg ulcers and other side effects. Control of hematocrit is not always achieved with HU and many patients are either intolerant of or become resistant to HU; second line therapeutic options are limited with no drugs approved in this setting. Janus kinase (JAK) 2 plays a key role in the pathophysiology of PV; nearly 100% of patients harbor either the JAK2V617F gain-of-function mutation or a JAK2 exon 12 mutation. In a phase II study in HU-resistant or -intolerant PV patients, INC424, a potent and selective inhibitor of JAK1 and JAK2, was well tolerated and achieved rapid and durable clinical responses including phlebotomy independence, resolution of splenomegaly, and improvements in white blood cell counts, platelet counts, and disease-related symptoms (Verstovsek S, et al. at 52nd ASH Annual Meeting; December 4–7, 2010. #313). Methods: RESPONSE, a global, open-label phase III trial (NCT01243944), is designed to compare the efficacy and safety of INC424 to Best Available Therapy (BAT) in adult patients with PV who are resistant to or intolerant of HU (by ELN criteria), require phlebotomy due to inadequate hematocrit control, and exhibit palpable splenomegaly ≥ 5 cm below the costal margin with either leukocytosis > 15 x 109/L and/or thrombocytosis > 600 x 109/L. The primary efficacy endpoint, assessed after 32 weeks of treatment, is based on achieving both phlebotomy independence and a ≥ 35% reduction in spleen volume as measured by imaging. All patients will be treated for 80 weeks to assess safety and response durability. Patients randomized to BAT may be eligible to cross over to receive INC424 after week 32. Enrollment is now open globally with a target of 300 patients to be randomized 1:1 to INC424 or BAT.

Durable Responses with the JAK1/ JAK2 Inhibitor, INCB018424, In Patients with Polycythemia Vera (PV) and Essential Thrombocythemia (ET) Refractory or Intolerant to Hydroxyurea (HU)

AbstractAbstract 313 Background:While advanced PV and ET patients at high thrombotic risk are managed primarily with HU, patients who are intolerant or refractory to HU have limited therapeutic options. Identification of a dominant gain-of-function mutation in the JAK2 kinase, V617F, in myeloproliferative neoplasms (MPNs), including PV and ET, provided a key rationale for the development of a molecularly targeted therapy for these diseases. Long term follow-up data from an ongoing trial of INCB018424, a selective JAK 1/ JAK 2 inhibitor, in PV and ET patients refractory or intolerant to HU are presented. Methods:Study 18424-256 is an uncontrolled open-label Phase 2 study being conducted at 6 sites in the United States and Italy. An initial 8-week run-in evaluation established 10-mg and 25-mg twice daily as starting doses for expansion cohorts in PV and ET, respectively; dose adjustments for safety and efficacy are allowed so that each subject is titrated to their most appropriate dose. For PV, response is defined based on Hct control in the absence of phlebotomy, improvement or elimination of palpable splenomegaly when present, and normalization of leukocytosis and thrombocytosis. For ET, response is defined based on improvement or normalization of WBC and platelet counts and, when present, elimination of palpable splenomegaly. PV results (n=34; median 108 months from diagnosis):After a median follow-up of 15 months (range 8–21), 97% of enrolled subjects achieved Hct control to <45% in the absence of phlebotomy, and all continued to maintain phlebotomy-independence at the time of last follow-up visit. Splenomegaly was present in 74% of subjects at entry: 59% of those achieved ≥ 50% reduction in palpable spleen length, or the spleen became non-palpable with all maintaining spleen response at the time of the last follow-up visit. Leukocytosis > 15×109/L was present in 47% of subjects and improved (≤ 15×109/L) or normalized (≤ upper limit of normal) in 88% and 63%, respectively. Thrombocytosis > 600×109/L was present in 38% of subjects and improved (≤ 600×109/L) or normalized (≤ upper limit of normal) in 92% and 69%, respectively. 59% of subjects achieved phlebotomy independence, resolution of splenomegaly and normalization of leukocytosis and thrombocytosis. 6 patients discontinued therapy (3 due to AEs, 2 withdrew consent, 1 for no response). Grade 3 AEs potentially related to study medication included thrombocytopenia (2 patients), neutropenia (1), renal tumor (1), asthenia (1), viral infection (1), and atrial flutter (1). No Grade 4 drug-related AEs have occurred. ET results (n=39; median 84 months from diagnosis):After a median follow-up of 15 months (range 4–21), 49% of enrolled subjects normalized platelet counts to ≤ upper limit of normal after a median of 0.5 months and for a median duration of 3.5 months. 82% maintained platelet counts < 600×109/L, for a median duration of 9.8 months. Of 14 patients with baseline platelet counts > 1000×109/L, 13 have experienced > 50% reduction. 88% maintained normal WBC (median duration 14.5 months). Palpable spleens resolved in 3 of 4 subjects; 1 reduced >50% from baseline. 49% of subjects achieved normalization of WBC and platelet counts in the presence of non-palpable splenomegaly. 9 patients discontinued therapy (4 due to AEs, 2 withdrew consent, 3 for no response). Grade 3 AEs potentially related to study medication included leukopenia (2 patients), GI disorder (1), and peripheral neuropathy (1). No Grade 4 drug-related AEs have occurred. Both patient groups demonstrated reductions in patient-reported symptom scores for pruritus, night sweats, and bone pain. Of 26 PV patients reporting pruritus at baseline (median score of 6 on a 10-point scale), 24 reported scores of 0 after a median duration of 1 month and for a median duration of 7 months. 42% of PV and 56% of ET patients had at least a 20% decrease in JAK2V617F allele burden; 6% of PV and 12% of ET had >50% decrease. Clinical responses were unrelated to the presence/absence of JAK2V617F mutation at entry or to the allele burden changes following treatment. Conclusions:Rapid and durable clinical benefits (normalization of hematological parameters, resolution of splenomegaly and alleviation of symptoms) have been demonstrated in advanced PV and ET patients with >1 year of follow-up. In this study, INCB018424 continues to be a well tolerated, effective therapy in patients with PV and ET refractory or intolerant to hydroxyurea. Disclosures:Verstovsek:Incyte Corporation: Research Funding. Levy:Incyte Corporation: Employment, Equity Ownership. Bradley:Incyte Corporation: Employment. Garrett:Incyte Corporation: Employment. Vaddi:Incyte corporation: Employment. Huber:Incyte Corporation: Employment, Equity Ownership. Schacter:Pfizer Corporation: Employment. Vannucchi:Novartis: Membership on an entity's Board of Directors or advisory committees.

Fludarabine and Rituximab (FR) Is a Safe and Effective Treatment Alternative for Relapsed or Refractory Hairy Cell Leukemia (HCL)

Abstract 2454 Background: Purine nucleoside analogs have been shown to produce high remission rates of 75–90% when used as first-line monotherapy for HCL. Long-term studies have shown that remissions may be lasting but are not durable. Median progression-free survival is approximately 8 years. Fludarabine (F) is an attractive option for treatment of relapsed HCL due to its similar mechanism of action, the ability to administer multiple courses for repeated exposure and its oral bioavailability. Rituximab (R) has shown single-agent activity in HCL as well as synergy with fludarabine in vivo. In addition, clinical trials have demonstrated that FR is effective in other indolent B-cell lymphoproliferative disorders. We assessed the tolerability and efficacy of FR for relapsed or refractory HCL. Patients and Methods: The British Columbia Cancer Agency (BCCA) Lymphoid Cancer Database was searched to identify patients treated with FR for relapsed or refractory HCL (F 40 mg/m2/d orally d 1–5 [adjusted for renal function] and R 375 mg/m2 IV d 1, every 28 days for 4 cycles). All cases were centrally reviewed to exclude variant HCL and splenic marginal zone lymphoma. Results: 252 patients with HCL were identified, of whom 90 developed progressive disease after initial therapy (36%). 13 patients were treated with FR between 2004–2009 for relapsed or refractory disease after first-line cladribine (n=2) or after multiple lines of therapy (n=11). Median age at FR was 59 years (range, 46–82 years); 85% of patients were male. Patients were heavily pre-treated with a median of 2 prior systemic treatments (range, 1–5). All patients had received at least 1 course of cladribine; 5 had received 2 courses (38%). Additional systemic treatments included interferon (n= 5, 38%) and deoxycoformycin (n= 4, 31%). A purine analogue was the therapy immediately prior to FR in all patients with cladribine in 11 (85%) and fludarabine alone in 2 (15%). 11 patients had a response to their last course of purine analog therapy, while 2 patients had refractory disease. FR therapy was administered at a median of 12.9 years from diagnosis (range, 3.4 –27.5) and at a median of 58 months from the last therapy (range, 2–155). Prior to FR therapy, the average interval between therapies was 46 months (range, 15–165). Median counts at time of FR were (data missing on 2 patients): hemoglobin 115 g/L (range, 79–145), white blood cell count 2.2 × 109/L (range, 0.9–8.6), lymphocyte count 1.0 × 109/L (range, 0.4–7.14), neutrophil count 1.09 × 109/L (range, 0.3–1.6), and platelets 98 × 109/L (range, 29–203). Patients underwent a median of 4 cycles of FR (range, 2–4) with oral fludarabine well tolerated in all cycles. Treatment was discontinued in 1 patient after 2 cycles due to a hypersensitivity reaction to rituximab and fludarabine was discontinued in 1 patient after 3 cycles due to the development of interstitial lung disease. The latter patient went on to receive a total of 6 rituximab infusions. Herpes zoster occurred in 2 patients, during and 6 months after completion of FR therapy, respectively. No patients required hospitalization during therapy. Information regarding response was available in 10 patients. All 10 patients had complete normalization of peripheral blood counts, absence of abnormal circulating lymphocytes and resolution of splenomegaly if present at initiation of FR. 3 patients had bone marrow biopsies at completion of therapy and all showed an absence of minimal residual disease by immunophenotyping. Currently, 12 patients (92%) remain in remission without further therapy while 1 patient has developed recurrent disease, 31 months after FR. With a median follow-up of 26 months from FR (range, 5–72), progression-free survival is 80% and overall survival 100%. Conclusion: In this multiply relapsed and heavily pre-treated group of patients with HCL, including patients previously exposed to purine analog therapy, the combination of oral fludarabine and rituximab was well tolerated, safe and effective. FR is a reasonable treatment option for patients with relapsed or refractory HCL. Disclosures: Off Label Use: Rituximab is being included because of previously documented phase II clinical trial activity against hairy cell leukemia.

Phase II Study of Sequential Therapy with Cladribine Followed by an Extended Course Rituximab in Patients with Hairy Cell Leukemia

AbstractAbstract 2458 Background:Although the nucleoside analogs cladribine (2CDA) and pentostatin are effective in the initial therapy of patients (pts) with HCL, complete remissions (CR) are not universal and relapses do occur. Methods:We have investigated whether an extended 8 week course of therapy with weekly rituximab after 2CDA can improve responses and eradicate minimal residual disease (MRD). Multicolor flow cytometry (MFC) was used to identify MRD by co-expression of CD103 and CD25 on CD19+ B-cells, with an assay sensitivity of 0.02%. MRD was also assessed by immunoglobulin heavy chain (IgH) polymerase chain reaction (PCR) assay using framework-1, -2 and -3 primer sets. 2CDA 5.6 mg/m2 IV was administered over 2 hours daily for 5 days. Approximately 1 month after initiation of 2CDA, bone marrow (BM) MRD was assessed and rituximab 375 mg/m2 IV was given weekly for 8 weeks. Responses were recorded and BM MRD was reevaluated after the completion of rituximab. Patients with untreated HCL (including variant form, HCLv) and those relapsing after 1 prior therapy were eligible. Results:To date, 45 pts have been treated including 38 with newly diagnosed HCL (4 with HCLv), and 7 (1 with HCLv) after relapse from 1 prior therapy (2CDA in 6 pts, chlorambucil in 1 pt). The median age of the pts was 54 years (range 32–89). Twenty five of 29 (86%) evaluable pts had mutated IgVH gene whereas IgVH was unmutated in 4 pts. 45 of 45 pts (100%) have achieved CR, defined as presence of no hairy cells in BM and blood with normalization of counts (ANC >1.5 × 109/L, Hgb >12.0 g/dL, Plt > 100 × 109/L), as well as resolution of splenomegaly, after completion of all therapy; MRD by MFC was positive in 33 of 37 (89%) evaluable pts after 2CDA therapy but became negative in 28 of 37 (76%) evaluable pts after rituximab. MRD by PCR was positive in 21 of 34 (62%) evaluable pts after 2CDA therapy and became negative in 27 of 38 (71%) evaluable pts after rituximab. Median serum IL-2 receptor level (reference range, 200–1100 U/mL) prior to initiation of therapy was 6661 U/mL (range, 458–44671). This fell to 1867 U/mL (range, 38–6661) after 2CDA and to 553 U/mL (range, 237–1673) after rituximab. The regimen was well tolerated with no grade 3 or 4 non-hematological adverse events directly related to the drugs. Only one pt (with HCLv) has relapsed; median CR duration has not been reached (range 3+ - 66+ months). Two pts developed another malignancy, pancreatic cancer in one and lung cancer in another, and died; while the pt with HCLv died from relapsed disease. Median survival duration has not been reached (range, 5+ - 71+ months). Conclusions:Chemo-immunotherapy with 2CDA followed by an extended course of rituximab may increase CR rate and duration and is effective in eradicating MRD in HCL. This regimen is also effective in pts with HCLv although responses may be less durable. Disclosures:Ravandi: Genentech: Research Funding. Off Label Use: Off label use of rituximab in hairy cell leukemia. Thomas: Novartis: Honoraria; Bristol-Meyer-Squibb: Honoraria; Pfizer:; Amgen: Research Funding.

Characterization of JAK2 V617F Allele Burden in Advanced Myelofibrosis (MF) Patients: No Change in V617F:WT JAK2 Ratio in Patients with High Allele Burdens despite Profound Clinical Improvement Following Treatment with the JAK Inhibitor, INCB018424

Background: Activating mutations in the pseudokinase domain of JAK2 occur at a high frequency in Philadelphia chromosome-negative myeloproliferative disorders (MPDs). Increasing JAK2 V617F allele burden has been shown to correlate with disease severity (bone marrow dysfunction, organomegaly and constitutional symptoms), which is consistent with exaggerated JAK2 signaling playing a central role in MPDs. INCB018424 is a potent and selective JAK1/2 inhibitor currently being evaluated in the clinic for the treatment of MPDs including primary myelofibrosis (PMF), post-polycythemia vera and essential thrombocythemia myelofibrosis (Post-PV/ET MF).Methods: The percentage of mutant JAK2 V617F relative to wild-type JAK2 was determined in peripheral blood using a quantitative single-nucleotide extension assay. The assay is based on the single nucleotide extension of a DNA primer that anneals adjacent to the V617F mutation. The percentage of JAK2 V617F in bone marrow was determined using pyrosequencing as previously described. The relationship between JAK2 V617F allele burden and clinical phenotype was assessed with samples obtained at study entry. JAK2 V617F allele burden was assessed in nineteen PMF and Post-PV/ET MF patients treated with 25 mg BID INCB018424 for a minimum of three months using peripheral blood and bone marrow.Results: There is an excellent correlation in the JAK2 V617F allele burden between samples obtained from bone marrow and peripheral blood, suggesting that the fraction of cells bearing the mutant clone remains stable during hematopoiesis in this patient group. The mean %V617F values were 59%, 80% and 86% for Post-ET MF (n=2), Post-PV MF (n=8) and PMF (n=9) patients. V617F allele burden correlated with spleen size, absolute neutrophil count (ANC) and Body Mass Index (BMI) in this patient population (R2 values if 0.61, 0.17 and 0.44, respectively), with a higher allele burden predicting larger spleen size, a higher ANC and a lower BMI. Eighteen of the nineteen evaluable JAK2 V617F-positive patients had baseline JAK2 V617F values above 50%, with the mean %V617F value for all evaluable patients being 81%, implying that the majority of hematopoietic stem cells contain the mutant allele in this patient population. During INCB018424 therapy (at least 3 months of treatment) in these patients, profound improvements in clinical endpoints including reduction or resolution of splenomegaly and constitutional symptoms are observed, yet only a modest decrease in JAK2 V617F allele burden is seen in both bone marrow and peripheral blood (13% and 9 % decrease from baseline, respectively, at 3 months).Conclusions: While the patient group is small and heterogeneous in nature, clinical correlates of V617F allele burden observed in myelofibrosis patients in this study are similar to those reported in PV. In addition, despite profound clinical improvements in these patients, V617F allele burdens do not change dramatically suggesting that the clinical activity of INCB018424 might involve inhibition of downstream signaling in cells harboring activating JAK2 mutations rather than changing the allele burden.

Imatinib Mesylate Therapy for Patients (pts) with Polycythemia Vera (PV).

Imatinib is a potent inhibitor of tyrosine kinases, including abl, c-kit, and platelet-derived growth factor receptor (PDGFR). A role for PDGF in PV has been suspected, and direct inhibition of PV colonies with imatinib has been reported. We initiated a phase II trial of imatinib in pts with PV diagnosed by the Polycythemia Vera Study Group criteria. Pts were treated with imatinib at 400 mg daily; if no significant response after 1 month (mo) of therapy, the dose could be escalated to 800 mg daily. Hydroxyurea could be used only during the first mo of therapy, but anagrelide was allowed at any time. 9 patients have been treated (6 male, 3 female). Median age was 51 years (yrs) (range 28 to 72 yrs); median duration of PV was 8 years (range 1/4–35 years). ECOG performance status was 0 for 2 pts and 1 for 7 pts. Most common symptoms included fatigue (n=7), intractable pruritus (n=5) and headache (n=4). 4 pts had splenomegaly, 1 had hepatomegaly, and 1 had prior splenectomy. All patients were dependent on repeated phlebotomies. All pts had diploid cytogenetics except one who had 20q− (prior therapy with 32 P). FISH and PCR confirmed absence of Bcr-Abl translocation. After a median follow-up of 4 mo (range, 2 to 37 mo), 3 pts have ≥50% reduction in phlebotomy requirements. These include one pt with complete remission defined as hemoglobin &lt; 14 g/dl, no phlebotomies and complete resolution of splenomegaly. Pruritus improved significantly in 3 pts; fatigue improved in 3 pts, headache and visual symptoms improved in one pt each. The dose of imatinib was increased to 800 mg in 3 pts. Grade 3 diarrhea and liver dysfunction occurred in 1 pt requiring dose reduction to 300 mg daily. Grade 2 toxicities included edema (n=2), rash (n=1), bone pain (n=1) and diarrhea (n=1). We conclude that imatinib has activity in PV, leading to improved symptoms and decreased phlebotomy requirements.