Philip D. Hall

Single-Dose Rasburicase 6 mg in the Management of Tumor Lysis Syndrome in Adults

Rasburicase is currently approved at a dosage of 0.15–0.2 mg/kg once/day for 5 days in pediatric patients with cancer to lower plasma uric acid concentrations and manage tumor lysis syndrome (TLS). Information on rasburicase dosing in adults is limited, with some data on using rasburicase as a single dose instead of multiple daily doses. Therefore, we evaluated the efficacy of a single dose of rasburicase for preventing or managing TLS in adults. We collected retrospective data for 11 adults with hematologic malignancies who received a single 6‐mg dose of rasburicase. All patients received intravenous hydration with urinary alkalinization and allopurinol; however, due to adverse reactions, two patients received short courses of allopurinol. Only patients at high risk for TLS (e.g., large tumor burden, increasing uric acid concentration) or those with TLS received rasburicase. The single dose of rasburicase 6 mg resulted in a median 0.0773‐mg/kg dose (range 0.0232–0.1361 mg/kg). The single 6‐mg dose rapidly lowered uric acid concentrations in 10 of the 11 patients. The median uric acid concentration of 11.7 mg/dl (range 7.4–17.4 mg/dl) declined to 2.0 mg/dl (range 0.5–15.4 mg/dl) within a day after rasburicase administration (p=0.022). In these 10 patients, uric acid concentrations remained low despite subsequent chemotherapy, and none required additional rasburicase doses. The only patient who did not respond to the single 6‐mg rasburicase dose was a morbidly obese man (259 kg, body mass index 87 kg/m2) who subsequently responded to an additional dose of rasburicase 12 mg. These results warrant further investigation of a single 6‐mg dose of rasburicase in adults with TLS or at high‐risk for developing TLS.

Treatment of acute myeloid leukemia during the second and third trimesters of pregnancy

Fortunately, the occurrence of acute myeloid leukemia (AML) during pregnancy is rare. We report a case of successful fetal outcome with standard induction and consolidation treatment in the second and third trimesters, respectively. A 37‐year‐old woman in her second trimester (21 wks) of pregnancy was found to have acute myeloid leukemia. She elected to maintain the pregnancy and underwent induction with cytarabine and idarubicin. Her hospital course was complicated by Pseudomonas vesicularis and gram‐positive bacilli (not Bacillus anthracis) septicemia, but she obtained complete remission. After discharge, a fetal echocardiogram at 26 weeks revealed a mildly dilated right ventricle with mild systolic dysfunction, and the left ventricle appeared smaller than normal with mild systolic dysfunction. The patient then received consolidation therapy with high‐dose cytarabine. On day 14 of consolidation, filgrastim 16 μg/kg was added to improve stem cell mobilization. A total of 19.8 times 106 CD34+ cells/kg were collected with a single apheresis session. At 37 weeks, she delivered a viable female infant weighing 3 lbs 12 oz. Fetal abnormalities included acrocyanosis, shallow sacral dimple, short digits and limbs, and prominent frontal skull with mild macrognathia. A postnatal echocardiogram revealed a moderate‐sized membranous ventricular septal defect. The ventricular septal defect proved significant and required surgical repair at 5 months. Approximately 4 weeks after delivery, the mother underwent autologous peripheral stem cell transplantation. Unfortunately, 100 days after transplantation, she had a relapse of AML. After a brief remission from a second induction, the patient died.

DT388-GM-CSF, a novel fusion toxin consisting of a truncated diphtheria toxin fused to human granulocyte-macrophage colony-stimulating factor, prolongs host survival in a SCID mouse model of acute myeloid leukemia

Despite significant advances in the treatment of acute myeloid leukemia (AML), the majority of patients will succumb to drug-resistant AML. To overcome this resistance, we have developed a novel fusion toxin consisting of the catalytic and translocation subunits of diphtheria toxin (DT388) linked to human granulocyte–macrophage colony-stimulating factor (GM-CSF). In vitro, DT388-GM-CSF demonstrated significant activity against numerous AML cell lines and fresh AML blasts. To determine its in vivo efficacy, we developed an in vivo model of human AML in severe combined immunodeficiency (SCID) mice injected intravenously with 1 × 107 HL-60 cells (AML-M2 cell line). The SCID mice developed abdominal masses, infiltration of the liver and bone marrow, and peripheral blasts with a median survival of 42.5 days. We tested DT388-GM-CSF, ara-C, human GM-CSF, and DAB389IL-2, which were injected intraperitoneally on days 2–6 in this model. DT388-GM-CSF significantly improved survival of the SCID mice over Ara-C, DAB389IL-2, or control (P < 0.001). dt388-GM-CSF-treated mice who developed leukemia exhibited no difference in the number of GM-CSF receptors (P = 0.39), ligand affinity (P = 0.77), or sensitivity (P = 0.56) to DT388-GM-CSF as compared to the controls. Frank leukemia in DT388-GM-CSF-treated mice may be due to incomplete penetration of drug into tissues rather than cellular resistance. DT388-GM-CSF is an active therapeutic agent in our SCID mouse model of AML with a unique mechanism of action and differing toxicities than current cytotoxic agents.

Diphtheria toxin fused to granulocyte-macrophage colony-stimulating factor and Ara-C exert synergistic toxicity against human AML HL-60 cells

Human granulocyte-macrophage colony-stimulating factor fused to truncated diphtheria toxin (DT388-GM-CSF) sensitized wild-type and Bcl2-overexpressing HL60 human leukemia cells to intoxication by Ara-C based on proliferation and clonogenic assays. The toxin/drug combination showed dramatic synergistic toxicity with combination indices of < 0.1. Synergy was not seen with two other protein synthesis inhibiting drugs--ricin and cycloheximide nor with GMCSF alone. No changes in Ara-C incorporation into cellular DNA or cell cycle occupancy were seen. As compared to exposure to DT388-GM-CSF or Ara-C alone, co-treatment produced significant increases in cytosolic accumulation of cytochrome c, a higher percentage of cells with loss of mitochondrial membrane potential and an increase in reactive oxygen species and morphologic changes of apoptosis, and a greater induction of poly(ADP-ribose) polymerase (PARP) and DNA fragmentation factor 45 (DFF45) cleavage activities of caspase 3. Co-treatment did not significantly alter Bcl2, Bcl-xL, Bax or Fas receptor (FasR), but modestly increased Fas ligand (FasL) protein. These finding suggest that co-treatment with DT388-GM-CSF may lead to a lowered apoptotic threshold and clonogenic survival of human AML blasts due to Ara-C. These observations also suggest that clinical trials of combination therapy may be warranted in patients with AML.

Toxicology and Pharmacokinetics of DT388IL3, a Fusion Toxin Consisting of a Truncated Diphtheria Toxin (DT388) Linked to Human Interleukin 3 (IL3), in Cynomolgus Monkeys

The fusion toxin DT388IL3 composed of the catalytic and translocation domains of diphtheria toxin (DT388) linked to interleukin-3 (IL3) was administered to 6 cynomolgus monkeys which possessed cross-reactive IL3 receptors. Groups of 2 animals (1 male and 1 female) received up to 6 every other day slow intravenous infusions of 40, 60, or 100 microg/kg DT388IL3. Monkeys given 40 or 60 microg/kg showed mild or moderate transient malaise and anorexia, respectively, without evidence of organ damage by blood tests or histopathology. Animals treated at 100 microg/kg showed severe malaise and anorexia. The female monkey had moderate to severe vasculitis in multiple tissues. Necropsies were performed on the 40 microg/kg monkeys on day 14 and the 100 microg/kg monkeys on days 6 and 7. DT388IL3 plasma half-life was approximately 30 min with a peak concentration of 0.45 microg/ml or 10,000 pM (IC50 for AML blasts treated in vitro was 6 pM). Immune responses were minimal in 4 animals tested at 12 days and 2 animals tested at 30 days post treatment with anti-DT388IL3 levels < 1 microg/ml. Bone marrow aspirates were obtained on all animals at day 19 or at necropsy and revealed myeloid suppression in the females and myeloid hyperplasia in the males irrespective of dose groups. The maximal tolerated dose of 60 microg/kg for 6 doses is markedly higher than other recombinant diphtheria toxins and provides a dose level sufficient for anti-leukemic activity in vitro and in rodent models. Thus, we propose this agent is a promising drug for AML patients.

A Phase I and pharmacokinetic study of high dose tamoxifen and weekly cisplatin in patients with metastatic melanoma

The authors have previously demonstrated that tamoxifen (TAM) is synergistic with cisplatin (DDP) in patients with metastatic melanoma. In vitro studies have demonstrated that TAM/DDP synergy is dependent on a TAM effect that is currently under investigation. In an attempt to improve the complete response rate of this regimen, the authors initiated a Phase I trial to determine the maximum tolerated dose (MTD) of TAM that could be safely administered with weekly DDP.

Fentanyl-associated syndrome of inappropriate antidiuretic hormone secretion

A 43–year‐old woman with advanced pulmonary blastoma was admitted for worsening back pain. Her drug regimen included hydromorphone and benazepril. On admission, hydromorphone patient‐controlled analgesia (PCA) was started for acute pain control and dexamethasone for possible cord compression. Baseline laboratory tests were unremarkable, but magnetic resonance imaging revealed T3 and L3 lesions. Irradiation was started with improvement in her pain. In anticipation of discharge, a fentanyl transdermal patch was given, and PCA was tapered. Two days later, the patient became progressively confused and fell. Neurologic examination and computed brain tomography were normal. Her serum sodium was 119 mEq/L (normal 136–144 mEq/L) and was confirmed on repeat testing, urine sodium was 194 mEq/L, and urine and serum osmolalities were 554 mOsm/kg (normal 300–900 mOsm/kg) and 245 mOsm/kg (normal 280–300 mOsm/kg), respectively, consistent with the syndrome of inappropriate antidiuretic hormone secretion (SIADH). Fluids were restricted, hydromorphone PCA was started again, and fentanyl was discontinued. After 36 hours, her serum sodium increased to 136 mEq/L. Because we were unsure whether the fentanyl or her cancer was causative and were unable to find any published reports of fentanyl‐associated SIADH, we readministered the fentanyl patch 2 days later. Within 48 hours, serum sodium dropped to 123 mEq/L. Fentanyl was discontinued, fluids were restricted, and 3% saline was started. Her serum sodium increased to 132 mEq/L in 48 hours. The patient was prescribed oral hydromorphone and benazepril and was discharged. The repeated temporal relationship between the administration of fentanyl and the onset of SIADH strongly implicates fentanyl as the causative agent in this case. To our knowledge, this is the first report of fentanyl‐associated SIADH.

Ricin fusion toxin targeted to the human granulocyte-macrophage colony stimulating factor receptor is selectively toxic to acute myeloid leukemia cells

Treatment failure of patients with acute myelogenous leukemia (AML) is frequently due to the development of multidrug resistance phenotype blasts. We have expressed a fusion protein consisting of human granulocyte-macrophage colony stimulating factor (GMCSF) fused to the N-terminus of a lectin-deficient ricin toxin B chain (RTB) in Spodoptera frugiperda insect cells. The fusion protein was purified by immunoaffinity chromatography and reassociated with chemically deglycosylated ricin toxin A chain (RTA). The resulting fusion toxin was found to react with antibodies to GMCSF, RTB and RTA and had the predicted molecular mass of 80 kDa. GMCSF-ricin bound poorly to asialofetuin (Kd = 10(6) M-1) and receptor negative cells indicating loss of lectin activity, but bound strongly to GMCSF receptor positive HL60 cells. Ligand displacement assays showed fusion toxin affinity 2.6-fold less than native GMCSF. Selective inhibition of protein synthesis was observed on receptor positive cells. Induction of apoptosis was also observed on receptor positive cells. Cells expressing multidrug resistance gene products (P-gp, Bcl2 and BclXL) were also sensitive to fusion toxin. These results suggest that GMCSF-ricin deserves further preclinical development.

Immunomodulation with intravenous immunoglobulin

Since its introduction over a decade ago for the treatment of primary immunodeficiencies, intravenous immunoglobulin (IVIG) has demonstrated activity in a variety of autoimmune disorders. An understanding of IVIGs immunomodulatory effects provides the rationale for its potential application in the management of autoimmune disorders. The agent has exhibited the ability to block fragment crystallizable receptors on phagocytes, interact with the idiotype‐anti‐idiotype network, and modulate T lymphocyte, B lymphocyte, and natural killer cell populations, as well as complement activity. Its immunomodulatory effects have been demonstrated in a variety of disorders such as idiopathic thrombocytopenic purpura, Guillain‐Barré syndrome, Kawasaki disease. Numerous case reports and small studies revealed IVIGs activity in a variety of other autoimmune disorders, but controlled clinical trials are necessary to clarify these initial observations.

Toxicities of Gemcitabine in Patients with Severe Hepatic Dysfunction

Objective To determine the relationship between doses of gemcitabine and absolute neutrophil count and thrombocytopenia in patients with severe hepatic dysfunction (total bilirubin ≥4.5 mg/dL), and the relationship between doses of gemcitabine in patients with severe hepatic dysfunction and nonhematologic toxicity. Case summary A retrospective chart review was conducted for patients receiving gemcitabine at the Medical University of South Carolina from October 2006 through October 2008. Seven patients were identified who had an elevated total bilirubin level (≥4.5 mg/dL) at the time they were receiving gemcitabine. All 7 patients received gemcitabine 1000 mg/m2 throughout their treatment, regardless of liver function. Six patients did not experience significant hematologic toxicity warranting a dose reduction or a dose being held. One patient developed thrombocytopenia, warranting a dose being held. Discussion Gemcitabine is a chemotherapy agent frequently used for the treatment of pancreatic cancer as well as metastatic breast, lung, and ovarian cancer. To date there is limited information on dosing of gemcitabine in patients with an elevated total bilirubin. A previous study looking at lower grades of liver dysfunction suggested empiric dose reductions be made in these patients because of increased incidence of toxicity. Conclusions These results indicate the possibility that no initial dose reduction is necessary for patients with liver dysfunction receiving gemcitabine; however, close monitoring of these patients is required.