Impact of metformin on tyrosine kinase inhibitor response in chronic myeloid leukemia.

OBJECTIVE: Oral tyrosine kinase inhibitors (TKIs) are first line therapy for chronic myeloid leukemia (CML). A complete cytogenetic response (CCyR) correlates with increased overall survival, however only 66%-88% of patients achieve CCyR after one year of TKI treatment. Because TKI therapy alone cannot eliminate CML stem cells, strategies aimed at achieving faster and deeper responses are needed to improve long-term survival. Metformin is a widely prescribed glucose-lowering agent for patients with diabetes and in preclinical studies, has been shown to suppress cell viability, induce apoptosis, and downregulate the mTORC1 signaling pathway in imatinib resistant CML cell lines (K562R). This study aims to investigate the utility of metformin added to TKI therapy in patients with CML. DATA SOURCES: An observational study at an academic medical center (Salt Lake City, UT) was performed for adults with newly diagnosed, chronic-phase CML to evaluate attainment of CCyR from TKI therapy with or without concomitant metformin use. Descriptive analyses were used to describe baseline characteristics and attainment of response to TKI therapy. DATA SUMMARY: Fifty-nine patients were evaluated. One hundred percent (5 of 5) in the metformin group and 73.6% (39 of 54) in the non-metformin group achieved CCyR. Approximately 20% of patients in both groups relapsed (defined by a loss of CCyR during study) after a median 34.5 months of follow-up. CONCLUSIONS: Future research is warranted to validate these findings and determine the utility of metformin added to TKI therapy.

Efficacy and safety of ferric carboxymaltose infusion in reducing anemia in patients receiving chemotherapy for nonmyeloid malignancies: A randomized, placebo-controlled study (IRON-CLAD).

Erythropoiesis-stimulating agents (ESA) are effective for chemotherapy-induced anemia (CIA) but associated with serious adverse events. Safer alternatives would be beneficial in this population. The efficacy and safety of ferric carboxymaltose (FCM) as monotherapy for CIA was evaluated. This Phase 3, 18-week, double-blind, placebo-controlled study randomized adults with ≥ 4 weeks of chemotherapy remaining for treatment of nonmyeloid malignancies with CIA to FCM (two 15 mg/kg infusions 7 days apart; maximum dose, 750 mg single/1500 mg total) or placebo. The primary efficacy endpoint was percentage of patients with decreases in hemoglobin (Hb) ≥ 0.5 g/dL from weeks 3 to 18; the key secondary efficacy endpoint was change in Hb from baseline to week 18. Inclusion criteria included: (Hb) 8-11 g/dL, ferritin 100-800 ng/mL, and transferrin saturation (TSAT) ≤35%. In 244 patients (n = 122, both groups), the percent of patients who maintained Hb within 0.5 g/dL of baseline from weeks 3 to 18 was significantly higher with FCM versus placebo (50.8% vs. 35.3%; p = 0.01). Mean change in Hb from baseline to week 18 was similar between FCM and placebo (1.04 vs. 0.87 g/dL) but significantly greater with FCM with baseline Hb ≤ 9.9 g/dL (1.08 vs. 0.42 g/dL; p = 0.01). The percent with ≥ 1 g/dL increase from baseline was significantly higher with FCM versus placebo (71% vs. 54%; p = 0.01), occurring in a median 43 versus 85 days (p = 0.001). Common adverse events in the FCM arm included neutropenia (17%), hypophosphatemia (16%), and fatigue (15%). FCM monotherapy effectively maintained Hb and was well tolerated in CIA.

How I treat cancer-associated anemia.

Despite increasing use of targeted therapies to treat cancer, anemia remains a common complication of cancer therapy. Physician concerns about the safety of intravenous (IV) iron products and erythropoiesis-stimulating agents (ESAs) have resulted in many patients with cancer receiving no or suboptimal anemia therapy. In this article, we present 4 patient cases that illustrate both common and complex clinical scenarios. We first present a review of erythropoiesis and then describe our approach to cancer-associated anemia by identifying the contributing causes before selecting specific treatments. We summarize clinical trial data affirming the safety and efficacy of currently available IV iron products used to treat cancer-associated anemia and illustrate how we use commonly available laboratory tests to assess iron status during routine patient management. We compare adverse event rates associated with IV iron vs red cell transfusion and discuss using first-line IV iron monotherapy to treat anemic patients with cancer, which decreases the need for ESAs. A possible mechanism behind ESA-induced tumor progression is discussed. Finally, we review the potential of novel therapies such as ascorbic acid, prolyl hydroxylase inhibitors, activin traps, hepcidin, and bone morphogenetic protein antagonists in treating cancer-associated anemia.

The Role of Intravenous Iron in the Treatment of Anemia Associated with Cancer and Chemotherapy.

Cancer-related anemia (CRA) is a commonly occurring problem for patients with cancer regardless of whether they are receiving treatment with chemotherapy or immunotherapy. It may result from one or more processes (decreased production, increased destruction, or increased loss of red blood cells, RBC). Perturbations in iron availability form the primary basis for anemia in many patients with cancer-related anemia. Functional iron deficiency (FID) anemia is a condition in which the patient has adequate or increased iron stores, but this iron pool is not available for erythropoiesis. Erythropoiesis-stimulating agents (ESAs) were the original treatment for FID; over time, however, if the supply of iron cannot keep pace with increased RBC synthesis driven by ESAs, FID may eventually lead to the lack or loss of ESA responsiveness. Subsequent clinical trials reported that intravenous (IV) iron could enhance the erythropoietic response to ESAs. This chapter reviews the pathogenesis of FID and summarizes the literature on the treatment of cancer- and chemotherapy-induced anemia. Clinical trials using IV iron with or without ESAs are reviewed in addition to the currently available IV iron products. The consensus conclusions from these trials, as well as guideline recommendations, support the use of IV iron in these patients to enhance ESA responsiveness, decrease ESA dosage, and reduce RBC transfusions. Little data have been published on the long-term safety of IV iron or its impact on tumor growth. This paper also briefly explores novel approaches for the treatment of FID anemia, which has relevance in treating not only cancer patients but also patients with benign inflammatory disorders.

Dynamic dosing of romiplostim in patients with immune thrombocytopenia purpura: Two case reports.

Romiplostim is a thrombopoietin receptor agonist approved for the treatment of immune thrombocytopenia purpura. When following FDA-approved romiplostim prescribing recommendations to withhold treatment for platelet counts above 400k/µL, some patients exhibit a precipitous decline in their platelet count potentially causing patient harm. We present two cases where stable platelet counts were achieved only through persistent weekly dosing of romiplostim despite platelet counts above 400k/µL on the day of administration. Therefore, continuous weekly dosing of romiplostim despite platelet count being above 400k/µL combined with twice weekly vigilant monitoring is an alternative method of romiplostim dosing that mitigates severe fluctuations in platelets. We also discuss important details, postulated mechanisms, and evidence-based mitigation strategies.

Pralatrexate Monitoring Using a Commercially Available Methotrexate Assay to Avoid Potential Drug Interactions.

Pralatrexate (PDX) is a folate antagonist structurally similar to methotrexate (MTX). Unlike MTX, it is currently not known whether PDX exhibits delayed clearance and heightened toxicity in the setting of fluid overload. A specific serum assay for PDX is not commercially available. To our knowledge, we report the first case using an MTX serum assay as a surrogate for PDX concentrations to avoid a potential drug-drug interaction with pralatrexate. We describe a 76-year-old man with refractory cutaneous T-cell lymphoma who began therapy with weekly PDX 15 mg/m(2) intravenous infusions on days 1, 8, and 15 of a 28-day cycle. He subsequently developed mucositis, a moderate right-sided pleural effusion, and peripheral edema over the next 5 weeks. Aggressive diuresis with furosemide was initiated, which was then withheld the day before his next PDX dose to avoid a potential drug-drug interaction between PDX and furosemide. His baseline MTX/PDX concentration (measured prior to administration of the cycle 2, week 2 PDX dose) was less than 0.20 µmol/L (i.e., undetectable). After PDX administration, his 1-hour peak MTX/PDX concentration increased to 0.58 µmol/L. Aggressive diuresis was withheld until his MTX/PDX concentration was undetectable, 43.5 hours later. PDX is more potent than MTX and displays similar pharmacokinetic properties. PDX concentrations using the serum MTX assay reflect lower values than those reported from PDX-specific assays in clinical studies. Because PDX is approved by the U.S. Food and Drug Administration for the treatment of uncommon malignancies, it is unlikely that a specific assay will be commercially developed. We propose that the MTX serum assay has merit for use in determining when to reinstate possible interacting drug therapies such as loop diuretics.

Diagnosis and treatment of cancer-related anemia.

Cancer-related anemia (CRA) is due to multiple etiologies, including chemotherapy-induced myelosuppression, blood loss, functional iron deficiency, erythropoietin deficiency due to renal disease, marrow involvement with tumor as well as other factors. The most common treatment options for CRA include iron therapy, erythropoietic-stimulating agents (ESAs), and red cell transfusion. Safety concerns as well as restrictions and reimbursement issues surrounding ESA therapy for CRA have resulted in suboptimal treatment. Similarly, many clinicians are not familiar or comfortable using intravenous iron products to treat functional iron deficiency associated with CRA. This article summarizes our approach to treating CRA and discusses commonly encountered clinical scenarios for which current clinical guidelines do not apply.

Comparison of acute toxicity and mortality after two different dosing regimens of high-dose interleukin-2 for patients with metastatic melanoma.

We compared acute toxicity, drug exposure, in-hospital mortality, and inpatient length of stay between two currently recommended dosing protocols (from the National Comprehensive Cancer Network Guidelines) of high-dose interleukin-2 (IL-2) treatment for patients with metastatic melanoma. Patients with metastatic melanoma who received high-dose IL-2 treatment between 2003 and 2010 were identified. Chemotherapy orders, electronic medical records, paper medical charts, and patient discharge summaries were reviewed retrospectively. We identified 13 patients who had received 600,000 units/kilogram (kg)/dose and 15 patients who had received 720,000 units/kg/dose. Patients in the 720,000 units/kg/dose group had a higher rate of grade 3 and 4 bilirubin elevations (34 vs. 12 %), weight gain (any grade, 96 vs. 89 %), and thrombocytopenia (any grade, 75 vs. 65 %). Patients receiving the higher dose also experienced more dose-limiting neurotoxicity (45 vs. 23 %), large-volume diarrhea (15 vs. 0 %), and hepatotoxicity (7 vs. 0 %). There was no in-hospital mortality during treatment in either group. The average length of stay was similar between both groups (5 days, SD = 1 for both groups), and the median cumulative IL-2 exposure was similar between both groups for the first course (10.1 vs.10.5 million units/kg) and for all courses (approximately 11-12 million units/kg). Both high-dose IL-2 protocols had comparable in-hospital mortality and cumulative IL-2 exposure. The 720,000 units/kg/dose dosing scheme did not shorten the length of stay but did lead to greater acute toxicity. Therefore, as a result, we recommend 600,000 units/kg/dose when deciding between the two regimens.

Cancer- and chemotherapy-induced anemia.

Anemia is prevalent in 30% to 90% of patients with cancer. Anemia can be corrected through either treating the underlying cause or providing supportive care through transfusion with packed red blood cells or administration of erythropoiesis-stimulating agents (ESAs), with or without iron supplementation. Recent studies showing detrimental health effects of ESAs sparked a series of FDA label revisions and a sea change in the perception of these once commonly used agents. In light of this, the NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines) for Cancer- and Chemotherapy-Induced Anemia underwent substantial revisions this year. The purpose of these NCCN Guidelines is twofold: 1) to operationalize the evaluation and treatment of anemia in adult cancer patients, with an emphasis on those who are receiving concomitant chemotherapy, and 2) to enable patients and clinicians to individualize anemia treatment options based on patient condition.

Total dose iron dextran infusion in cancer patients: is it SaFe2+?

The feasibility of the large, single-dose intravenous iron repletion method, which is known today as total dose infusion (TDI), has been demonstrated over decades. However, this method of iron repletion was chiefly developed for patients with large iron deficits, such as those with pregnancy-induced anemia, chronic bleeding disorders, and absolute iron-deficiency anemia (serum ferritin < 30 ng/mL, transferrin saturation < 15%) who were unable to receive frequent small doses of intravenous iron. Today, 50 years after the advent of TDI, more is known about iron metabolism and storage, but the optimal dosing strategy for intravenous iron in patients with cancer is still not well defined. The proinflammatory state of cancer, or its treatment, may influence the response to intravenous iron therapy. Additionally, the long-term adverse effects of large single doses or smaller more frequent doses have yet to be studied in the oncology population. Historically, safety concerns surrounding the administration of intravenous iron have centered on anaphylaxis. Newer concerns are being raised, such as oxidative stress, iron overload, venous thromboembolism, infection risk, and tumor growth. Therefore, with the original premise of TDI assuming low levels of inflammation, coupled with the recent data surrounding the adverse effects of blood transfusions and erythropoietic-stimulating agents, this article reviews the risks and benefits of TDI administration specifically for patients with cancer.

Enoxaparin once daily vs. twice daily dosing for the treatment of venous thromboembolism in cancer patients: a literature summary.

Current anticoagulation guidelines for cancer patients are largely based upon studies done in the general population. Anticoagulation studies in cancer patients with venous thromboembolism (VTE) have compared varying doses of different low molecular weight heparins (LMWH) to warfarin or unfractionated heparin (UFH) regimens, and most guidelines recommend LMWH as the preferred agent over vitamin K antagonists. However, very few studies compare different dosing regimens of the LMWH itself. As a result, practitioners attempt to extrapolate results from studies done in the general medicine population and apply them to cancer patients with VTE. Considering the differences in risk factors and hypercoagulability between these populations, such generalizations may compromise outcomes or safety for cancer patients. Currently, no study to date has compared the safety and efficacy of enoxaparin 1.5 mg/kg subcutaneously (SC) once daily vs. 1 mg/kg SC twice daily in a prospective, randomized fashion, for the longterm treatment of VTE in patients with cancer. The purpose of this article is to review currently available literature utilizing these dosing schemes in order to risk-stratify cancer patients who may better qualify for one dosing regimen as compared to the other. Our analysis suggests that enoxaparin dosed at 1.5 mg/kg SC once daily may be a safe and effective alternative for the treatment of VTE in cancer patients with both a low risk of recurrent VTE and bleeding. In the absence of additional studies, the dosing of enoxaparin for cancer patients should be based on patient-specific risk factors.

Establishing an anemia clinic for optimal erythropoietic-stimulating agent use in hematology-oncology patients.

Erythropoietic-stimulating agent (ESA) therapy has significantly impacted the management of chemotherapy-induced anemia (CIA) by decreasing the number of red blood cell transfusions required by patients with cancer. However, managing these patients with ESA therapy has become increasingly difficult since the release of the Centers for Medicare & Medicaid Services' new National Coverage Determination document because of the disparities between this document and recommendations from expert-reviewed national clinical guidelines on the treatment of anemia. This article describes a collaborative practice agreement between pharmacists and physicians as one approach to managing CIA in hematology-oncology patients in an anemia clinic. The goal of the pharmacist-managed anemia clinic is to improve patient satisfaction and clinical outcomes associated with the treatment of CIA. This article describes the rationale for the clinic and discusses its design and implementation in managing ESA, iron, folate, and vitamin B12 therapy for CIA in hematology-oncology patients. The pharmacist's role is justified in this clinic model through increased adherence to evidence-based practice guidelines and decreased costs associated with ESA therapy.