Myelosuppressive Agents Research Articles

Rad18 confers hematopoietic progenitor cell DNA damage tolerance independently of the Fanconi Anemia pathway in vivo.

In cultured cancer cells the E3 ubiquitin ligase Rad18 activates Trans-Lesion Synthesis (TLS) and the Fanconi Anemia (FA) pathway. However, physiological roles of Rad18 in DNA damage tolerance and carcinogenesis are unknown and were investigated here. Primary hematopoietic stem and progenitor cells (HSPC) co-expressed RAD18 and FANCD2 proteins, potentially consistent with a role for Rad18 in FA pathway function during hematopoiesis. However, hematopoietic defects typically associated with fanc-deficiency (decreased HSPC numbers, reduced engraftment potential of HSPC, and Mitomycin C (MMC) -sensitive hematopoiesis), were absent in Rad18−/− mice. Moreover, primary Rad18−/− mouse embryonic fibroblasts (MEF) retained robust Fancd2 mono-ubiquitination following MMC treatment. Therefore, Rad18 is dispensable for FA pathway activation in untransformed cells and the Rad18 and FA pathways are separable in hematopoietic cells. In contrast with responses to crosslinking agents, Rad18−/− HSPC were sensitive to in vivo treatment with the myelosuppressive agent 7,12 Dimethylbenz[a]anthracene (DMBA). Rad18-deficient fibroblasts aberrantly accumulated DNA damage markers after DMBA treatment. Moreover, in vivo DMBA treatment led to increased incidence of B cell malignancy in Rad18−/− mice. These results identify novel hematopoietic functions for Rad18 and provide the first demonstration that Rad18 confers DNA damage tolerance and tumor-suppression in a physiological setting.

The Jak1/Jak2 Inhibitor Momelotinib Inhibits Alk2, Decreases Hepcidin Production and Ameliorates Anemia of Chronic Disease (ACD) in Rodents

▪Many patients with myelofibrosis (MF) develop anemia and are, or become, dependent on frequent red blood cell transfusions [1]. Results from the phase 2 studies for the treatment of myelofibrosis (MF) with the Jak1/2 inhibitor momelotinib (MMB) demonstrated that MMB treatment provided an anemia benefit, in addition to providing a durable spleen response and improvement in constitutional symptoms in MF patients [2]. MMB's anemia benefit was an unexpected outcome as erythropoietin (EPO)-mediated JAK2 signaling is essential for erythropoiesis [3, 4]. Systemic iron homeostasis is controlled by the peptide hormone hepcidin produced by the liver. Hepcidin reduces iron export from duodenal enterocytes and splenic and hepatic macrophages by binding to and down-regulating the iron exporter ferroportin [5-7]. In chronic disease, there is a significant increase in hepcidin levels which can result in severe anemia; this pathologic condition is termed anemia of chronic disease (ACD). Recently, MF patients have been shown to have elevated serum hepcidin levels and this increase is associated with inferior overall survival in these patients [8].This study aimed to determine whether MMB's clinical anemia benefit is driven by direct activity of MMB on the hepcidin pathway. We assayed MMB inhibitory activity on the BMP-receptor kinase pathway (the central driver of hepcidin transcription in hepatocytes) and assessed the activity of MMB in a rodent model of anemia of chronic disease (ACD). We demonstrate that MMB inhibits BMP6-induced in vitro production of hepcidin in cultured hepatocytes (HepG2 cells) with an EC50 = 651 +/- 203 nM (n=3). This inhibitory activity is mediated by direct suppresion of the BMP-receptor kinase Alk2 as MMB inhibits Alk2 enzymatic activity with an IC50 = 8.4 +/- 1.5 nM (n=3). Ruxolitinib has no activity on either Alk2 or the BMP-receptor kinase pathway. To understand whether MMB could modulate hepcidin levels in vivo and ameliorate anemia in vivo we assessed the effect of MMB in a peptidoglycan-polysaccharide fragment (PG-APS)-induced rat ACD model. Treatment with clinically relevant exposure levels of MMB for 3 days resulted in a dose dependent reduction in both liver RNA and serum protein hepcidin levels and caused an increase in serum iron. Furthermore, long-term treatment with MMB for 21 days increased the numbers and percent of reticulocytes and mature red blood cells in the bone marrow and increased Hgb and hematocrit to normal levels in the blood.Our data suggest that MMB's clinical anemia benefit results from inhibition of ALK2-mediated expression of hepcidin in the liver, which results in increased release of iron from sequestered cellular stores and enhanced erythropoiesis. A phase 2 translational study in anemic subjects with MPNs is scheduled to confirm this mechanism. The Alk2-mediated activity on iron metabolism through hepcidin could prove beneficial in a number of additional indications, and facilitate the combination of MMB with myelosuppressive agents.1. Tefferi, A., et al., One thousand patients with primary myelofibrosis: the mayo clinic experience. Mayo Clin Proc, 2012. 87 (1): p. 25-33.2. Pardanani, A., et al., Update On The Long-Term Efficacy and Safety Of Momelotinib, a JAK1 and JAK2 Inhibitor, For The Treatment Of Myelofibrosis. Vol. 122. 2013. 108-108.3. Verstovsek, S., et al., Safety and efficacy of INCB018424, a JAK1 and JAK2 inhibitor, in myelofibrosis. N Engl J Med, 2010. 363 (12): p. 1117-27.4. Verstovsek, S., et al., A double-blind, placebo-controlled trial of ruxolitinib for myelofibrosis. N Engl J Med, 2012. 366 (9): p. 799-807.5. Nemeth, E., et al., Hepcidin regulates cellular iron efflux by binding to ferroportin and inducing its internalization. Science, 2004. 306 (5704): p. 2090-3.6. Theurl, I., et al., Dysregulated monocyte iron homeostasis and erythropoietin formation in patients with anemia of chronic disease. Blood, 2006. 107 (10): p. 4142-8.7. Theurl, I., et al., Autocrine formation of hepcidin induces iron retention in human monocytes. Blood, 2008. 111 (4): p. 2392-9.8. Pardanani, A., et al., Associations and prognostic interactions between circulating levels of hepcidin, ferritin and inflammatory cytokines in primary myelofibrosis. Am J Hematol, 2013. 88 (4): p. 312-6. DisclosuresWarr:Gilead Science: Employment. Maciejewski:Gilead Science: Employment. Fowles:Gilead Science: Employment. Whitney:Gilead Sciences: Employment. Theurl:Gilead Science: Research Funding.

Control of Neutrophil Endothelial Transmigration By EC-18 in Chemotherapy Induced Neutropenia

▪Chemotherapy-induced neutropenia (CIN) is a common dose-limiting side-effect that often compromises chemotherapy resulting in dose reduction and/or delayed treatment. Chemotherapy-induced myeloid suppression is a prevalent mechanism to describe CIN. However, diapedesis of neutrophils from the blood is also a possible mechanism of CIN. Cytokines, chemokines, and damage- (or danger-) associated molecular pattern molecules (DAMPs) are produced from the damaged tissues by chemotherapy, which accelerates neutrophil transmigration. EC-18 is a synthetic monoacetyldiglyceride (MW=635) currently under development as an oral agent to treat and potentially prevent CIN. Here, we showed that neutrophil transmigration is induced in CIN model, and the efficacy and potential mechanism of EC-18 have been evaluated in mice and various cell models. Gemcitabine (50mg/Kg), cyclophosphamide (100mg/Kg) or tamoxifen (50mg/Kg) was administered daily for 3 days in mice (C57BL/6), followed by oral administrations of EC-18 (50mg/Kg) for 21 days. Blood neutrophils were analyzed by complete blood count (CBC) and fluorescence-activated cell sorting (FACS). All three chemotherapeutic agents significantly reduced absolute neutrophil count (ANC) in the blood; 40.4% decrease in gemcitabine, 19.8% in cyclophosphamide, and 21.8% in tamoxifen, which were recovered by the co-administration of EC-18. Microarray analysis of the lymph nodes from gemcitabine-treated mice revealed that the expression of DAMP molecules, S100A8 and S100A9, was induced by gemcitabine and decreased by the co-treatment of EC-18. Using immune cell lines, the expression of neutrophil transmigratory molecules, such as C3 anaphylatoxin, IL-6 and IL-8, was increased by gemcitabine treatment, and EC-18 blocked the expression of those cytokines in dose-dependent manners. Western blot analysis showed that EC-18 regulated STAT3 and STAT6 signaling pathways to modulate the expression of DAMPs, C3, IL-6, and IL-8. The decrease of C3 and IL-6 levels by EC-18 treatment was also verified in PBMCs from normal adults. In a pilot clinical study (WJON 2015 accepted, ASCO e20697), orally administrated EC-18 (1,000mg/day) alleviated neutropenic phenotypes in patients with pancreatic cancer who had been treated with gemcitabine (1,000mg/m2) and erlotinib (100mg daily). As a supportive oncology agent, EC-18 can maximize the antitumor efficacy of myelo-suppressive chemotherapeutic agents by enabling the treatment to continue or even higher doses to be administered. DisclosuresNo relevant conflicts of interest to declare.

Dose Delays, Dose Reductions, and Relative Dose Intensity in Patients With Cancer Who Received Adjuvant or Neoadjuvant Chemotherapy in Community Oncology Practices.

A wide variety of myelosuppressive chemotherapy regimens are used for the treatment of cancer in clinical practice. Neutropenic complications, such as febrile neutropenia, are among the most common side effects of chemotherapy, and they often necessitate delays or reductions in doses of myelosuppressive agents. Reduced relative dose intensity (RDI) may lead to poorer disease-free and overall survival. Using the McKesson Specialty Health/US Oncology iKnowMed electronic health record database, we retrospectively identified the first course of adjuvant or neoadjuvant chemotherapy received by patients without metastases who initiated treatment between January 1, 2007, and March 31, 2011. For each regimen, we estimated the incidences of dose delays (≥7 days in any cycle of the course), dose reductions (≥ 15% in any cycle of the course), and reduced RDI (<85% over the course) relative to the corresponding standard tumor regimens described in the NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines). This study included 16,233 patients with 6 different tumor types who received 1 of 20 chemotherapy regimens. Chemotherapy dose delays, dose reductions, and reduced RDI were common among patients treated in community oncology practices in the United States, but RDI was highly variable across patients, regimens, and tumor types (0.486-0.935 for standard tumor regimen cohorts). Reduced RDI was more common in older patients, obese patients, and patients whose daily activities were restricted. In this large evaluation of RDI in US clinical practice, physicians frequently administered myelosuppressive agents at dose intensities lower than those of standard regimens.

Minimal Toxicity From Systemic Therapy Given Concurrently With Stereotactic Radiosurgery for Brain Metastases

Chemotherapy is typically not given concurrently with whole brain radiation therapy (WBRT) for treatment of metastatic disease due to increased risk of myelosuppression and neurotoxicity. The goal of this study was to evaluate the prevalence, outcomes, and toxicities of concurrent delivery of systemic therapy with stereotactic radiosurgery (SRS) for treatment of brain metastases. We conducted a retrospective review of 196 patients treated with at least one course of SRS without WBRT for brain metastases between 2009 and 2014. Outcome metrics included the administration of concurrent systemic therapy, grade of myelosuppression, development of neurological symptoms, and overall survival. 196 patients with a median age of 61 years (range, 27-85 years) underwent a total of 290 SRS treatments, with a median of 2 lesions targeted per treatment. Histology included non-small cell lung cancer (40%), melanoma (18%), breast cancer (14%), renal cell cancer (9%), and other (18%). 39% of SRS treatments were delivered concurrently with systemic therapy (i.e. systemic therapy started prior to or during SRS and continued through SRS), of which 51% were with conventional myelosuppressive chemotherapy agents, and 49% were with less-myelosuppressive targeted and hormonal agents. The most common systemic agents included platinum chemotherapies (given with 35% of treatments), ipilimumab (17%), taxanes (16%), pemetrexed (13%), and trastuzumab (13%). Systemic therapy was given during the same week as SRS treatment in 79% of cases. Myelosuppression was minimal in patients treated with both systemic therapy and SRS, with median grade 0 leukopenia, neutropenia, and thrombocytopenia, and grade 1 lymphopenia and anemia over the 1 month following treatment. Grade 3-4 toxicity was minimal (9% of lymphopenia and 3-5% of leukopenia, neutropenia, anemia, and thrombocytopenia) and primarily seen in patients treated with conventional myelosuppressive agents. 52% of patients who received systemic therapy and SRS had neurological symptoms during the 1 month following treatment, and these included fatigue (62%), headache (21%), weakness (15%), and gait instability (15%). Patients treated with myelosuppressive versus non-myelosuppressive agents, as well as systemic therapy given within the same week or not, were equally likely to develop neurological symptoms. Dexamethasone was used in 26% of cases in the month following treatment. Median overall survival for the cohort was 16.9 months following SRS. Systemic therapy can be safely given concurrently with SRS for brain metastases, and this is an attractive option for patients who have both intracranial and extracranial metastatic disease. Our results suggest minimal myelosuppression and neurotoxicity across different systemic agents, even when delivered within the same week as SRS.

Hydroxyurea in sickle cell patients: A look at the correlation with hematologic malignancies.

e12593 Background: Hydroxyurea (HU) is a chemotherapeutic agent used in sickle cell patients (SCP) to reduce the frequency and intensity of sickle pain crises. It is a myelosuppressive agent with p...

Abstract P3-07-29: Association between adjuvant chemotherapy and risk of acute kidney injury in elderly women diagnosed with early stage breast cancer

Abstract Background: Acute kidney injury (AKI) is a serious complication of cancer and its treatment, causing delay or interruptions in cancer therapy and increased risk of adverse outcomes including premature death. Little is known from large population-based cohort studies about the association between chemotherapy (chemo) and risk of AKI in elderly cancer patients (pts). Methods: This retrospective cohort study used the linked Surveillance, Epidemiology, and End Results (SEER)-Medicare data. Women diagnosed with stages I-III breast cancer (BC) at ages 66-89 years between 1992-2007 were included. We performed 1-1 sequential matching on time-dependent propensity score on the day of adjuvant chemo initiation within 6 months (mos) after the first surgery. Follow-up (F/U) began on the matching date and ended at AKI occurrence, chronic kidney disease diagnosis, death, change in enrollment status, or 6 mos after the matching date. For pts in the matched untreated cohort, F/U time was also censored at chemo initiation. Chemo was identified in claims through billing codes indicating drugs or administration. Regimens of interest included anthracyclines (A), CMF, taxanes (T, no anthracyclines), and others. AKI was identified in hospital claims. The cumulative incidence of AKI was assessed using the Kaplan-Meier method. The association between adjuvant chemo and risk of AKI was evaluated using a Cox proportional hazards model. The analyses were repeated by regimen type. Results: The matched study cohorts included 28,048 pts. The mean (standard deviation) F/U time was 6.0 (0.8) mos for the chemo cohort and 4.3 (2.5) mos for the matched no-chemo cohort. The cumulative incidence of AKI at mos 1, 3, and 6 was 0.24%, 0.50%, and 0.80% for pts receiving chemo, compared with 0.05%, 0.17%, and 0.30% for no-chemo pts (P&amp;lt;0.001). Adjuvant chemo was associated with a 2.7-fold increased risk of AKI (HR 2.7, 95% CI 1.8-4.1; P&amp;lt;0.001), despite a very low overall incidence rate (16 and 6 per 1000 person-years in chemo and no-chemo pts, respectively). Further examination of distribution of other diseases coded on hospital claims in AKI pts showed that septicemia occurred in 40% of chemo-treated pts with AKI and in only 17% of untreated pts with AKI. Of chemo-treated pts, 53%, 31%, 7%, and 8% received an A-based, a CMF, a T-based, and other regimens, respectively. Each regimen was significantly associated with increased risk of AKI, with the strongest association for a T-based regimen (HR 4.2, 95% CI 2.2-7.8), the weakest for a CMF regimen (HR 2.2, 95% CI, 1.3-3.8), and intermediate associations for an A-based regimen (HR 2.5, 95% CI 1.6-4.1) and others (HR 3.0, 95% CI 1.5-6.2), but the effect of these regimens did not significantly differ from each other. Conclusion: Adjuvant chemo is associated with increased risk of AKI in elderly women diagnosed with early stage BC. This association may be partially explained by septicemia caused by infection/neutropenia due to use of myelosuppressive chemotherapeutic agents, highlighting the importance of preventing serious complications of chemo in preventing AKI. Citation Format: Shuling Li, Jiannong Liu, Beth A Virnig, Allan J Collins. Association between adjuvant chemotherapy and risk of acute kidney injury in elderly women diagnosed with early stage breast cancer [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P3-07-29.

Higher Risk of Infections with PI3K-AKT-mTOR Pathway Inhibitors in Patients with Advanced Solid Tumors on Phase I Clinical Trials.

Novel antitumor therapies against the PI3K-AKT-mTOR pathway are increasingly used to treat cancer, either as single agents or in combination with chemotherapy or other targeted therapies. Although these agents are not known to be myelosuppressive, an increased risk of infection has been reported with rapamycin analogues. However, the risk of infection with new inhibitors of this pathway such as PI3K, AKT, mTORC 1/2, or multikinase inhibitors is unknown. In this retrospective case-control study, we determined the incidence of infection in a group of 432 patients who were treated on 15 phase I clinical trials involving PI3K-AKT-mTOR pathway inhibitors (cases) versus a group of 100 patients on 10 phase I clinical trials of single agent non-PI3K-AKT-mTOR pathway inhibitors (controls) which did not involve conventional cytotoxic agents. We also collected data from 42 patients who were treated with phase I trials of combinations of PI3K-AKT-mTOR inhibitors and MEK inhibitors and 24 patients with combinations of PI3K-AKT-mTOR inhibitors and cytotoxic chemotherapies. The incidence of all grade infection was significantly higher with all single-agent PI3K-AKT-mTOR inhibitors compared with the control group [27% vs. 8%, respectively, OR, 4.26; 95% confidence intervals (CI), 1.9-9.1, P = 0.0001]. The incidence of grade 3 and 4 infection was also significantly higher with PI3K-AKT-mTOR inhibitors compared with the control group (10.3% vs. 3%, OR, 3.74; 95% CI, 1.1-12.4; P = 0.02). Also, the combination of PI3K-AKT-mTOR inhibitors and chemotherapy was associated with a significantly higher incidence of all grade (OR, 4.79; 95% CI, 2.0-11.2; P = 0.0001) and high-grade (OR, 2.87; 95% CI, 1.0-7.6; P = 0.03) infection when compared with single-agent PI3K-AKT-mTOR inhibitors. Inhibitors of the PI3K-AKT-mTOR pathway can be associated with a higher risk of infection. Combinations of PI3K-AKT-mTOR inhibitors and cytotoxic chemotherapy significantly increase the risk of infection. This should be taken into consideration during the design and conduct of trials involving PI3K-AKT-mTOR pathway inhibitors, particularly when combined with chemotherapy or myelosuppressive agents.

Busulfan as a myelosuppressive agent for generating stable high-level bone marrow chimerism in mice.

Bone marrow transplantation (BMT) is often used to replace the bone marrow (BM) compartment of recipient mice with BM cells expressing a distinct biomarker isolated from donor mice. This technique allows for identification of donor-derived hematopoietic cells within the recipient mice, and can be used to isolate and characterize donor cells using various biochemical techniques. BMT typically relies on myeloablative conditioning with total body irradiation to generate niche space within the BM compartment of recipient mice for donor cell engraftment. The protocol we describe here uses myelosuppressive conditioning with the chemotherapeutic agent busulfan. Unlike irradiation, which requires the use of specialized facilities, busulfan conditioning is performed using intraperitoneal injections of 20 mg/kg busulfan until a total dose of 60-100 mg/kg has been administered. Moreover, myeloablative irradiation can have toxic side effects and requires successful engraftment of donor cells for survival of recipient mice. In contrast, busulfan conditioning using these doses is generally well tolerated and mice survive without donor cell support. Donor BM cells are isolated from the femurs and tibiae of mice ubiquitously expressing green fluorescent protein (GFP), and injected into the lateral tail vein of conditioned recipient mice. BM chimerism is estimated by quantifying the number of GFP+ cells within the peripheral blood following BMT. Levels of chimerism>80% are typically observed in the peripheral blood 3-4 weeks post-transplant and remain established for at least 1 year. As with irradiation, conditioning with busulfan and BMT allows for the accumulation of donor BM-derived cells within the central nervous system (CNS), particularly in mouse models of neurodegeneration. This busulfan-mediated CNS accumulation may be more physiological than total body irradiation, as the busulfan treatment is less toxic and CNS inflammation appears to be less extensive. We hypothesize that these cells can be genetically engineered to deliver therapeutics to the CNS.

Busulfan as a Myelosuppressive Agent for Generating Stable High-level Bone Marrow Chimerism in Mice

Busulfan as a Myelosuppressive Agent for Generating Stable High-level Bone Marrow Chimerism in Mice

Erythropoiesis-stimulating agent hyporesponsiveness in end-stage renal disease patients.

Approximately 5-10% of patients with end-stage renal disease (ESRD) exhibit hyporesponsiveness to erythropoiesis-stimulating agents (ESAs), defined as a continued need for higher than 300 IU/kg/week doses of epoetin or a 1.5 mg/kg/week dose of darbepoetin. ESA hyporesponsiveness contributes to the morbidity, mortality and health-care economic burden of ESRD patients. The most common causes of ESA resistance are absolute or functional iron deficiency and inflammation. Maintaining adequate iron stores is clearly accepted as the most important strategy for reducing the ESA requirement and for enhancing ESA efficacy. Recent clinical studies have shown that iron administration to ESRD patients is associated with an increased risk of infection and atherosclerosis. ESA hyporesponsiveness due to chronic inflammation in ESRD patients has been reported to be improved by a number of interventions, including the use of biocompatible hemodialysis membranes, ultrapure dialysate, ascorbic acid therapy, vitamin E supplementation, and statin therapy. Other causes of ESA hyporesponsiveness include inadequate dialysis, hyperparathyroidism, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, primary bone marrow disorders, myelosuppressive agents, hemoglobinopathies, hemolysis, and hypersplenism. This article summarizes the common causes of ESA hyporesponsiveness and the proposed therapeutic interventions.

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...

Abstract P3-13-09: Relative dose intensity of taxane-based chemotherapy in patients with stage IV breast cancer

Abstract Background: Maintaining high relative dose intensity (RDI) has been associated with improved disease-free survival, progression-free survival, and overall survival of patients with breast cancer treated in the adjuvant setting. Neutropenia and related complications, such as febrile neutropenia, are common side effects of myelosuppressive chemotherapy that can lead to dose delays, dose reductions, and reduced RDI. Primary prophylaxis with colony-stimulating factors (CSFs) can reduce the duration and severity of neutropenia and the incidence of febrile neutropenia, thereby supporting high RDI. For patients with stage IV breast cancer, dose delays and dose reductions are frequently used to manage toxicity associated with myelosuppressive chemotherapy. However, the prevalence and impact of reduced RDI in the metastatic disease setting is poorly understood. Objective: To estimate mean chemotherapy RDI and incidences of dose delays, dose reductions, RDI &amp;lt;85%, and primary CSF prophylaxis among women with stage IV breast cancer receiving first-line chemotherapy. Methods: Using the McKesson Specialty Health/US Oncology iKnowMed™ electronic health record (HER) database, we retrospectively identified adult women with stage IV breast cancer who initiated first-line, intravenous, myelosuppressive chemotherapy from January 2007 to December 2010 in community oncology practices in the US. Patients were assigned to chemotherapy cohorts based on myelosuppressive agents received in cycle 1 and planned regimen information in the database. Standard chemotherapy regimens were defined based on NCCN breast cancer guidelines and clinical studies. Mean RDI and incidences of dose delays ≥7 days, dose reductions ≥15%, and RDI &amp;lt;85% in any cycle during the course of chemotherapy were evaluated relative to the standard chemotherapy regimen. Primary CSF prophylaxis was defined as first receipt of CSF during the first 5 days of chemotherapy cycle 1. Patients were followed for up to 6 months after chemotherapy initiation. Results: This study included 1471 patients with stage IV breast cancer who received myelotoxic chemotherapy. The most common chemotherapy regimens in the metastatic setting were taxane-based, and endpoints for the three most common chemotherapy regimens (n = 307) are shown in the Table. Paclitaxel/ BevacizumabaAlbumin-bound PaclitaxelbPaclitaxelcN1767556Age, mean (SD) years58.2 (11.9)63.6 (12.4)61.8 (13.8)RDI, mean (SE)89.0% (1.9)89.1% (3.1)89.0% (3.2)RDI &amp;lt;85%37.5%41.3%26.8%Dose delays ≥7 days36.9%22.7%32.1%Dose reductions ≥15%40.9%61.3%8.9%CSF primary prophylaxis0%1.3%3.6%aPaclitaxel 80-90 mg/m2 on days 1, 8, and 15 and bevacizumab 10 mg/kg on days 1 and 15 (cycle length 28 days). Paclitaxel dose at cycle 1, day 1 was defined as the standard dose for this regimen; bAlbumin-bound paclitaxel 100 mg/m2 on days 1, 8, and 15 (cycle length 28 days); cPaclitaxel 80 mg/m2 (cycle length 7 days). Conclusions: Chemotherapy dose delays, dose reductions, and reduced RDI were common in patients with stage IV breast cancer. The impact of RDI on progression-free and overall survival is being evaluated and will be presented. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P3-13-09.

The JAK Inhibitor Ruxolitinib Elicits Hematologic and Symptomatic Improvement In Patients With Chuvash Polycythemia

Chuvash polycythemia (CP) is a rare congenital polycythemia caused by mutations in the VHL gene. Patients with CP present with erythrocytosis and are at high risk for thrombosis. Accordingly, CP patients have a significantly reduced lifespan. Currently, there are no proven therapies for CP. Studies demonstrating a potential benefit from phlebotomy or myelosuppressive agents have been lacking.CP exhibits features of both secondary and primary polycythemia. The former has been attributed to dysfunction of the mutant VHL protein leading to upregulation of HIFa under normoxic conditions, thereby resulting in increased erythropoietin (Epo) production. The latter is manifested by hypersensitivity of CP erythryoid progenitors to Epo in vitro, but the mechanism for this finding has not been fully explained.Recently, the VHL protein was shown to target phosphorylated JAK2 (pJAK2) for ubiquitin-mediated degradation. CP-associated VHL mutants were unable to degrade pJAK2, thereby leading to hyperactivation of downstream STAT signaling. In a CP mouse model, treatment with a JAK2 inhibitor led to normalization of hematocrit and reduction in splenomegaly. These findings provide a strong rationale for JAK2 inhibition as a therapeutic modality for CP. We now report preliminary data from two CP patients treated with the JAK inhibitor ruxolitinib.Baseline and on-treatment characteristics for the two patients are summarized in Table 1. Both patients were confirmed to be homozygous for the VHL R200W mutation. CP-01 first presented with erythrocytosis at 18 months. He was treated with intermittent phlebotomies and underwent a splenectomy at age 10. The patient had multiple thrombotic complications, including a deep vein thrombosis, pulmonary embolism, and portal vein thrombosis. He suffered from recurrent episodes of severe abdominal pain presumed to be related to his history of intra-abdominal thrombosis. The patient had a hemoglobin as high as 22.0 g/dL, and required four phlebotomies in a span of four weeks to achieve a hematocrit of 45.2% prior to initiating ruxolitinib. [Display omitted] CP-01 was initiated on ruxolitinib at a starting dose of 10 mg orally twice daily and titrated up to the current dose of 20 mg twice daily. As of the most recent follow-up at 12 weeks, the patient has not required any phlebotomies since starting ruxolitinib and has not had any new episodes of abdominal pain.CP-02 was initially found to have erythrocytosis at the age of three. He was treated with intermittent phlebotomies but developed multiple thrombotic complications, including mesenteric vein thrombosis as well as a myocardial infarction at the age of 27. He also suffered from severe back pain presumed to be related to bone marrow expansion. The patient exhibited oscillations in his platelet count that were exacerbated after he underwent a splenectomy (platelet counts ranging between 7 x 109/L and 1900 x 109/L on a ∼30 day cycle). Periods of extreme thrombocytosis were associated with severe headaches requiring plateletpheresis.CP-02 was initiated on treatment with ruxolitinib, initially at a dose of 5 mg twice daily due to his periodic thrombocytopenia, and gradually titrated up to 20 mg twice daily. As of the most recent evaluation at 23 weeks, the patient reported significant improvement in his back pain, though he continued to require regular phlebotomies. His platelet count oscillations have improved dramatically, particularly at the current ruxolitinib dose of 20 mg twice daily (Figure 1). Strikingly, his lowest platelet count since starting ruxolitinib has been 187 x 109/L. This stabilization in his platelet count has been associated with an improvement in his headaches. [Display omitted] To our knowledge, these two cases represent the first CP patients treated with a targeted inhibitor of JAK2. Both patients have experienced hematologic and symptomatic improvement, with no significant safety issues to date. These preliminary observations validate pre-clinical studies suggesting a role for JAK2 inhibition in CP. Correlative studies examining endogenous erythroid colony formation, JAK-STAT signaling, and inflammatory cytokine levels are ongoing. Disclosures:Oh:Incyte: Consultancy, Research Funding, Speakers Bureau. Off Label Use: Ruxolitinib for Chuvash polycythemia.

Final Report Of Phase II Study Of Sorafenib and 5-Azacytidine In Patients With Relapsed Or Untreated Acute Myeloid Leukemia and FLT3-ITD mutation

BackgroundA potential mechanism of resistance to FLT3 kinase inhibitors is high levels of FLT3 ligand (FL) which is commonly seen after treatment with myelosuppressive chemotherapy. We hypothesized that combining sorafenib with a less myelosuppressive agent, such as 5-azacytidine (AZA), may lead to higher and more durable responses. Furthermore, differentiation of leukemic blasts has been reported with both agents. MethodsPatients were eligible if they had relapsed or refractory AML, were 18 years of age or older, and had adequate performance status (ECOG 2 2) and organ function. Patients older than 60 without prior therapy were also eligible if they were unsuitable to receive chemotherapy or refused it. Presence of FLT3-ITD was not a requirement but these patients were sought for participation in the study. Treatment regimen included AZA 75 mg/m2 daily for 7 days together with sorafenib 400 mg twice daily for 28 days; cycles were repeated in approximately 4 to 5-week intervals. Dose adjustments of both agents, and delay of AZA, based on toxicity were allowed. Plasma samples were collected on Day 1 and Day 10 of each cycle. ResultsOverall, 57 patients with AML with a median age of 65 years (range, 21-87) were enrolled. They included 27 (47%) patients with normal cytogenetics, 12 (21%) with chromosome 5/7 or complex cytogenetic abnormalities, 15 (26%) with other miscellaneous abnormalities; 3 (5%) had insufficient metaphases. Prior to the initiation of treatment, FLT3-ITD was detected in 53/57 (93%) patients with a median allelic ratio of 0.348 (range, 0.009 – 0.934). They had received a median of 2 prior treatments (range, 0 -7) including 13 previously untreated patients. Twenty (35%) patients had received ≥3 prior regimens and 12 had failed prior therapy with FLT3 kinase inhibitors (6 with AC220, 2 with PKC412, and 9 with sorafenib, either as monotherapy or with chemotherapy or plerixafor); 4 patients had failed 2 prior FLT3 inhibitors. The overall CR/CRi/PR rate among the 57 patients is 44%, including 16 (28%) with CRi and 8 (14%) with CR and 1 (2%) with PR. The response rate among the previously untreated patients was 62% and among relapsed patients 39%. Patients have received a median of 3 (range, 1 - 27) treatment cycles with the median number of cycles to response among the responders being 2 (range, 1 – 4) and the median time to achieving response, 2.1 months (range, 0.8 – 4.6 months). The median duration of CR/CRi Is 2.4 months (range, 0.8 – 24.8 months). Seven patients have proceeded to allogeneic stem cell transplant. The most common study drug-related adverse events were rash and fatigue with no deaths attributable to study medications. One patient developed grade 3 cardiomyopathy. With a median follow-up of 8.6 months (range, 6.1 – 26.9), 13 patients remain alive, 5 still in remission. The median overall survival of the 57 patients was 6.3 months, and 12.4 months in the 25 responding patients. Mean FL levels at cycle 2, day 0 and cycle 2, day 10 were 27 pg/mL and 54 pg/mL, respectively, which is significantly lower than those seen previously in studies of FLT3 kinase inhibitor plus chemotherapy. ConclusionsCombination of AZA and Sorafenib is effective for the treatment of patients with AML and FLT3-ITD. FL levels are significantly lower during the course of therapy with this combination compared to previously reported levels after chemotherapy. [Display omitted] Disclosures:Ravandi: Celgene: Consultancy, Research Funding.

A Report On a Phase 2 Trial Of Combination Therapy With Lenalidomide and Azacitidine In Patients With Non-Del 5q, Low Risk MDS

IntroductionLow risk MDS is a heterogeneous disease, with limited and short lived responses to available therapeutic options. We hypothesized that the combination of lenalidomide and azacitidine may result in higher response rates and longer duration of such responses than those achieved with either agent. MethodsThis was an investigator- initiated phase 2 trial, seeking to evaluate the safety , tolerability and response rate of the combination of lenalidomide and azacitidine in patients with low- int-1 risk MDS (excluding those with del 5q). Patients had to have up to three months of lenalidomide monotherapy, followed by response assessment per IWG 2006 criteria. Responders were to continue on lenalidomide until progression or failure. Non responders would receive 2 cycles of combination therapy with azacitidine at 25 mg/m2 for 5 days every 28 days, together with lenalidomide at the same dose they received in cycle 3. If no grade 4 toxicity developed, or if the initiation of the next cycle of therapy was not delayed by more than 2 weeks, patients would continue combination therapy, with dose escalation of azacitidine to 50 mg/m² on days 1 through 5 every 28 days for 4 more cycles along with same dose of lenalidomide received in prior cycles. Response assessment was to be performed after 6 cycles of combination therapy, with responders continuing to receive treatment until disease progression, intolerable toxicities or return to baseline transfusion dependence. ResultsBetween January of 2011 and November of 2012, we enrolled 2 patients, a 69 year old male (1), and a 65 year old female (2), both patients had RARS, normal karyotype, IPSS was 0, and 1. Patient (1) was previously treated with ESA/G-CSF, the other was treatment naïve. Both patients started Lenalidomide at 5 mg daily, due to reduced GFR (1). Treatment of patient (1) was complicated by severe anemia after 2 cycles of therapy, necessitating blood transfusion, dose reduction, and eventually holding therapy. The patient declined participation and was taken off study in September of 2011. Patient (2) was enrolled in August of 2012, received 3 cycles of lenalidomide at 5 mg daily, resulting in stable disease. She went on to receive two cycles of combination therapy. Treatment was complicated by a rash, attributed to revlimid, and hematological toxicity resulting in treatment delay by more than 2 weeks. Per protocol, she was taken off study. ConclusionOur study was closed prematurely, and our sample size is very small, but this experience suggests that Combination therapy in patients with low risk MDS is challenging on multiple levels: Accrual, tolerability of two myelosuppressive agents, and potentially, an unacceptable risk/benefit ratio. Disclosures:Shammo:celgene: Consultancy, Honoraria, Research Funding. Off Label Use: The use of lenalidomide and azacitidine in combination for the treatment of low risk MDS.

Are MPNs Vascular Diseases?

A high risk of arterial and venous thrombosis is the hallmark of chronic myeloproliferative neoplasms (MPNs), particularly polycythemia vera (PV) and essential thrombocythemia (ET). Clinical aspects, pathogenesis and management of thrombosis in MPN resemble those of other paradigmatic vascular diseases. The occurrence of venous thrombosis in atypical sites, such as the splanchnic district, and the involvement of plasmatic prothrombotic factors, including an acquired resistance to activated protein C, both link MPN to inherited thrombophilia. Anticoagulants are the drugs of choice for these complications. The pathogenic role of leukocytes and inflammation, and the high mortality rate from arterial occlusions are common features of MPN and atherosclerosis. The efficacy and safety of aspirin in reducing deaths and major thrombosis in PV have been demonstrated in a randomized clinical trial. Finally, the Virchow's triad of impaired blood cells, endothelium and blood flow is shared both by MPN and thrombosis in solid cancer. Phlebotomy and myelosuppressive agents are the current therapeutic options for correcting these abnormalities and reducing thrombosis in this special vascular disease represented by MPN.

Hydroxyurea in sickle cell disease: drug review.

Hydroxyurea, a myelosuppressive agent, is the only effective drug proven to reduce the frequency of painful episodes. It raises the level of HbF and the haemoglobin level. It usually decreases the rate of painful episodes by 50%. It was first tested in sickle cell disease in 1984. It also decreases the rate of ACS episodes and blood transfusions by ~50% in adults. It was developed as an anticancer drug and has been used to treat myeloproliferative syndromes-leukemia, melanoma, and ovarian cancer. It was approved for use by FDA in adults. Side effects includes neutropenia, bone marrow suppression, elevation of hepatic enzymes, anorexia, nausea, vomiting and infertility.

Combination of Sorafenib and 5-Azacytidine Has Significant Activity in Patients with Relapsed/Refractory or Untreated Acute Myeloid Leukemia and FLT3-ITD mutation

Abstract 1519▪▪This icon denotes a clinically relevant abstract Background:The outcome of patients (pts) with acute myeloid leukemia (AML) and FLT3-ITD mutation is poor, particularly in the relapse setting. Sorafenib is a potent inhibitor of FLT3 kinase with reported clinical activity as a single agent (Metzelder S, Blood, 2009), and in combination with chemotherapy (Ravandi F, JCO, 2010). A potential mechanism of resistance to FLT3 kinase inhibitors is high levels of FLT3 ligand (FL) as seen after myelosuppressive chemotherapy. We hypothesized that combining sorafenib with a less myelosuppressive agent, such as 5-azacytidine (AZA), may lead to higher and more durable responses than cytotoxic chemotherapy. Furthermore, both drugs have demonstrated a potential for inducing differentiation in AML cells, thereby providing further rationale for the combination. Methods:Pts were eligible if they had relapsed or refractory AML, were 18 years of age or older, and had adequate performance status (ECOG ≤ 2) and organ function. Older pts without prior therapy were also eligible, if they were deemed unsuitable to receive chemotherapy. Presence of FLT3-ITD was not a requirement but these pts were targeted for enrollment. Treatment regimen included AZA 75 mg/m2 daily for 7 days together with sorafenib 400 mg twice daily for 28 days; cycles were repeated in approximately 4 to 5-week intervals. Overall responses were assessed after the completion of at least one cycle of therapy and at the time of the best peripheral blood and bone marrow response. Plasma samples were collected on approximately Day 1 and Day 10 of each cycle. To assess the degree of FLT3 inhibition, the plasma inhibitory activity (PIA) assay was performed using the Molm-14 cell line (Levis M, Blood, 2006). Plasma FL concentrations were measured using an ELISA kit (R&D Systems). Results:43 pts with AML with a median age of 64 years (range, 24–87) were enrolled. They included 19 (44%) pts with diploid cytogenetics, 11 (26%) with chromosome 5/7 or complex cytogenetic abnormalities, and 13 (30%) with miscellaneous abnormalities. Prior to the initiation of treatment, FLT3-ITD was detected in 40/43 (93%) pts with a median allelic ratio of 0.28 (range, 0 – 0.93). They had received a median of 2 prior treatments (range, 0–7). 16 (37%) pts had received ≥3 prior regimens and 9 had failed therapy with FLT3 kinase inhibitors (5 with AC220, 1 with PKC412, and 6 with sorafenib, either as monotherapy or with chemotherapy or plerixafor); 3 had failed 2 prior FLT3 inhibitors. 6 pts were inevaluable as they discontinued therapy before response assessment at one month and 3 are too early for response assessment. The overall CR/CRi/PR rate among the 34 evaluable pts is 44%, including 10 (29%) with CRi and 4 (12%) with CR and 1 (3%) with PR (in this pt, bone marrow blast declined from 51% to 6% with normalization of blood counts). Overall, pts have received a median of 3 (range, 1–9) treatment cycles with the median number of cycles to response among the responders being 2 (range, 1 – 4) and the median time to achieving response, 2.1 months (range, 0.9 – 4.6 months). The median duration of CR/CRi Is 2.3 months (range, 1 – 12.2+ months). Six pts have proceeded to allogeneic stem cell transplant. The most common study drug-related adverse events were rash and fatigue with no deaths attributable to study medications. One pt developed grade 3 cardiomyopathy suspected to be related to the study regimen. Of the 34 pts included in the clinical analysis, there were 22 pts from whom plasma samples spanning at least one cycle of therapy were available. Among them, 64% achieved FLT3 inhibition to a targeted level of less than 15% of baseline during their first cycle of therapy. Median survival in pts who achieved this degree of inhibition was 238 days, while median survival in pts who did not reach this level was 154 days (p=0.13). Mean FL levels at cycle 1, day 1 and cycle 1, day 10 were 9 pg/mL and 17 pg/mL, respectively. Mean FL levels at cycle 2, day 0 and cycle 2, day 10 were 27 pg/mL and 54 pg/mL, respectively. Conclusions:Combination of AZA and Sorafenib is effective for the treatment of older pts and pts with relapsed and refractory AML and FLT3-ITD mutation. While not statistically significant, there was a trend toward improved survival in pts with adequate FLT3 inhibition during cycle 1. FL levels did not rise to the levels seen in pts receiving cytotoxic chemotherapy. Disclosures:Ravandi:Bayer/Onyx: Honoraria, Research Funding; Celgene: Honoraria, Research Funding. Off Label Use: Off-label use of sorafenib and 5-azacytidine in patients with acute myeloid leukemia. Levis:Astellas Pharma: Consultancy; Plexxikon: Consultancy; Symphogen: Consultancy. Garcia-Manero:Celgene: Research Funding. Andreeff:Hoffmann-La Roche: Research Funding; Karyopharm Therapeutics: Unrestricted gift, Unrestricted gift Other. Cortes:Celgene: Research Funding.

Rituximab-PECC Induction Followed by 90y-Ibritumomab Tiuxetan Consolidation in Relapsed or Refractory DLBCL Patients Who Are Not Eligible for or After ASCT: Preliminary Results From a Phase II HOVON Study.

AbstractAbstract 2729 Background.Patients with relapsed or refractory diffuse large B-cell lymphoma (DLBCL) after- or not eligible for autologous stem cell transplantation (ASCT) have a poor prognosis. The optimum salvage therapy for these patients is not known. Treatment results with second-line chemotherapy have generally been disappointing. In some centers in the Netherlands PECC (Prednisone, Etoposide, Chlorambucil and Lomustine) combination chemotherapy is used as salvage treatment for such patients. PECC is a completely oral schedule. The efficacy and toxicity of PECC in this patient category has not been evaluated systematically before. 90Y-ibritumomab tiuxetan (Zevalin®) showed clinical activity as a single agent in relapsed DLBCL. We conducted a prospective multi-center phase II study evaluating induction therapy with Rituximab (R)-PECC followed in responsive patients by 90Y-ibritumomab tiuxetan consolidation. Methods.Patients aged ≥ 18 years with refractory CD20 positive DLBCL or first or second relapse, more than one year after or not eligible for ASCT, were enrolled. Treatment consisted of R-PECC (Prednisone 40 mg/m2 po D1–5; Etoposide 100 mg/m2 po D1–5; Chlorambucil 8 mg/m2 po D1–5; Lomustine 80 mg/m2 po D1 and Rituximab 375 mg/m2 iv D1), every 28 days for 4 cycles. Patients with progressive disease after 2 cycles went off protocol. Patients in complete or partial remission after 4 cycles received consolidation treatment with 90Y-ibritumomab tiuxetan at the standard single dose of 15 MBq/kg (0.4 mCi/kg) 6 to 12 weeks after start of the last R-PECC cycle. Response to treatment was evaluated according to the revised 2007 Cheson criteria. Results.Between November 2008 and February 2012 64 patients were enrolled. We report preliminary data for the first 50 patients evaluable for response and toxicity after the induction treatment with R-PECC. The median age was 70 years (range, 45–82) and median time since first diagnosis was 17 months (range 3–172). All patients had been treated with CHOP as first-line treatment and 8 patients (16%) had not been exposed to rituximab at first-line. Prior therapies consisted of (R)-CHOP (72%), R-CHOP and R-DHAP/VIM (16%) or R-CHOP and R-DHAP/VIM plus ASCT (12%). Eleven patients (22%) were refractory to their last prior systemic therapy. According to the secondary IPI, 26%, 28%, 34% and 8% of the patients belonged to the low-, low-intermediate-, high-intermediate-, and high risk group, respectively. Median relative dose intensities for the myelosuppressive agents of the PECC regimen were 93.7% (90% CI = 62.8–106.9%), 94.3% (90% CI = 71.6–104.7%) and 97.4% (90% CI 76.0–104.7%) for Lomustin, Etoposide and Chlorambucil, respectively. Progressive disease occurred in 14 patients (28%). Overall response rate (ORR) after induction treatment was 52%, including 34% complete response and 18% partial response. ORR of relapsed patients was significantly higher than that of patients refractory to their last prior treatment (64% vs. 9%, p=0.099). Patients more than one year from start of upfront treatment had a significant higher ORR than that of patients less than one year from start of upfront treatment (81% vs 21%, p=0.005). Median response duration was 13 months. One patient died because of treatment related toxicity due to sepsis and pneumonia after the first R-PECC cycle. The most common grade 3 or 4 adverse event was haematological toxicity (42%), followed by infection (14%), malaise (13%) and gastro-intestinal toxicity (6%). Eighteen serious adverse events (SAEs) occurred in 14 patients, 14 of the SAEs were possibly related to treatment (mainly hospitalisations because of infections). Approximately half of the patients (46%) have entered the 90Y-ibritumomab tiuxetan consolidation phase of the study. Conclusions.The R-PECC regimen shows good clinical activity in relapsed DLBCL patients. Its activity in refractory patients is low. This largely oral regimen provides patients not eligible for high-dose salvage treatment with a convenient treatment schedule with an acceptable safety profile. Disclosures:Off Label Use: 90Y-ibritumomab tiuxetan is not registered for DLBCL.