The intravenous and oral pharmacokinetics of afoxolaner and milbemycin oxime when used as a combination chewable parasiticide for dogs.

The pharmacokinetics of afoxolaner and milbemycin oxime (A3 and A4 forms) in dogs were evaluated following the oral administration of NexGard Spectra® (Merial), a fixed combination chewable formulation of these two active pharmaceutical ingredients. Absorption of actives was rapid at levels that provide the minimum effective doses of 2.5 mg/kg and 0.5 mg/kg of afoxolaner and milbemycin oxime, respectively. The time to maximum afoxolaner plasma concentrations (tmax ) was 2-4 h. The milbemycin tmax was 1-2 h. The terminal plasma half-life (t1/2 ) and the oral bioavailability were 14 ± 3 days and 88.3% for afoxolaner, 1.6 ± 0.4 days and 80.5% for milbemycin oxime A3 and 3.3 ± 1.4 days and 65.1% for milbemycin oxime A4. The volume of distribution (Vd ) and systemic clearance (Cls) were determined following an IV dose of afoxolaner or milbemycin oxime. The Vd was 2.6 ± 0.6, 2.7 ± 0.4 and 2.6 ± 0.6 L/kg for afoxolaner, milbemycin oxime A3 and milbemycin oxime A4, respectively. The Cls was 5.0 ± 1.2, 75 ± 22 and 41 ± 12 mL/h/kg for afoxolaner, milbemycin oxime A3 and milbemycin oxime A4, respectively. The pharmacokinetic profile for the combination of afoxolaner and milbemycin oxime supports the rapid onset and a sustained efficacy for afoxolaner against ectoparasites and the known endoparasitic activity of milbemycin oxime.

Safety evaluation of orally administered afoxolaner and milbemycin oxime in eight-week-old dogs.

The safety profile of afoxolaner (an isoxazoline molecule) when combined with milbemycin oxime (a macrocyclic lactone) was evaluated according to the regulatory requirements when administered six times orally in a soft chewable formulation at a dose of at least 1×, 3×, or 5× the maximum exposure dose in 8-week-old Beagle dogs. Thirty-two healthy puppies (16 males and 16 females) were enrolled and allocated randomly to one of four treatment groups. Three doses were administered at 28-day intervals (Days 0, 28, and 56), followed by three additional doses administered with 14-day intervals (Days 84, 98, and 112). The study ended on Day 126. Treatment groups were as follows: Group 1: untreated, sham-dosed control; Group 2: afoxolaner/milbemycin oxime chews administered at a dose of at least 5 and 1 mg/kg, respectively (1×); Group 3: afoxolaner/milbemycin oxime chews administered at a dose of at least 15 and 3 mg/kg, respectively (3); and Group 4: afoxolaner/milbemycin oxime chews administered at a dose of at least 25 and 5 mg/kg, respectively (5×). All dogs were examined for general health twice a day beginning on Day -14. Physical examinations, and blood collections for clinical pathology analysis and afoxolaner and milbemycin oxime plasma concentrations, were performed throughout the study. No afoxolaner/milbemycin oxime treatment-related changes were observed in growth, physical variables, clinical pathology variables, or tissues examined histologically. No clinically relevant or statistically significant health abnormalities related to the administration of afoxolaner/milbemycin oxime were observed. No signs of macrocyclic lactone sensitivity were observed at any time during the study. Vomiting and diarrhea were observed sporadically across all groups including the controls. Based upon the results of this study, afoxolaner/milbemycin oxime soft chewables were shown to be safe when administered repeatedly at up to 5× the maximum exposure dose in dogs as young as 8 weeks of age.

Pharmacokinetics of gamithromycin in cattle with comparison of plasma and lung tissue concentrations and plasma antibacterial activity.

The pharmacokinetics (PK) and dose proportionality of gamithromycin (ZACTRAN), a novel azalide, after a single intravenous (i.v.) dose of 3 mg/kg or subcutaneous (s.c.) injection at 3, 6 and 9 mg/kg body weight were studied in 13 male castrate and 13 female Angus cattle. Following i.v. administration, the mean area under the curve extrapolated to infinity (AUC(inf)) was 4.28 +/- 0.536 microgxh/mL, and mean elimination half-life (t(1/2)) was 44.9 +/- 4.67 h, with a large volume of distribution (V(ss)) of 24.9 +/- 2.99 L/kg and a high clearance rate (Cl(obs)) of 712 +/- 95.7 mL/h/kg. For cattle treated with s.c. injection of 3, 6 or 9 mg/kg, mean AUC(inf) values were 4.55 +/- 0.690, 9.42 +/- 1.11 and 12.2 +/- 1.13 microgxh/mL, respectively, and the mean elimination half-lives (t(1/2)) were 51.2 +/- 6.10, 50.8 +/- 3.80 and 58.5 +/- 5.50 h. Gamithromycin was well absorbed and fully bioavailable (97.6-112%) after s.c. administration. No statistically significant (alpha = 0.05) gender differences in the AUC(Inf) or elimination half-life values were observed. Dose proportionality was established based on AUC(Inf) over the range of 0.5 to 1.5 times of the recommended dosage of 6 mg/kg of body weight. Further investigations were conducted to assess plasma PK, lung/plasma concentration ratios and plasma antibacterial activity using 36 cattle. The average maximum gamithromycin concentration measured in whole lung homogenate was 18 500 ng/g at first sampling time of 1 day ( approximately 24 h) after treatment. The ratios of lung to plasma concentration were 265, 410, 329 and 247 at 1, 5, 10 and 15 days postdose. The lung AUC(inf) was 194 times higher than the corresponding plasma AUC(inf). The apparent elimination half-life for gamithromycin in lung was 90.4 h ( approximately 4 days). Antibacterial activity was observed with plasma collected at 6 h postdose with a corresponding average gamithromycin plasma concentration of 261 ng/mL. In vitro plasma protein binding in bovine plasma was determined to be 26.0 +/- 0.60% bound over a range of 0.1-3.0 microg/mL of gamithromycin. The dose proportionality of AUC, high bioavailability, rapid and extensive distribution to lung tissue and low level of plasma protein binding are beneficial PK parameters for an antimicrobial drug used for the treatment and prevention of bovine respiratory disease.

Absolute lymphocyte count recovery after induction chemotherapy predicts superior survival in acute myelogenous leukemia.

Absolute lymphocyte count (ALC) recovery postautologous stem cell transplantation is an independent predictor for survival in acute myelogenous leukemia (AML). The role of ALC recovery after induction chemotherapy (IC) in AML is unknown. We hypothesize that ALC recovery after IC has a direct impact on survival. We have now evaluated the impact of ALC recovery after IC on overall survival (OS) and leukemia-free survival (LFS) in 103 consecutive, newly diagnosed AML patients treated with standard IC and consolidation chemotherapy (CC) from 1998 to 2002. ALC recovery was studied at days 15 (ALC-15), 21 (ALC-21), 28 (ALC-28) after IC and before the first CC (ALC-CC). Superior OS and LFS at each time point were observed with an ALC-15, ALC-21, ALC-28, and ALC-CC > or = 500 cells/microl. Patients with an ALC > or = 500 cells/microl at all time points vs those who did not have superior OS and LFS (not reached vs 13 months, P<0.0001; and not reached vs 11 months, P<0.0001, respectively). Multivariate analysis demonstrated ALC > or = 500 cells/microl at all time points to be an independent prognostic factor for survival. Our data suggest a critical role of lymphocyte (immune) recovery on survival after IC in AML.

Allogeneic stem cell transplantation and donor lymphocyte infusions for chronic myelomonocytic leukemia.

Prognosis in chronic myelomonocytic leukemia (CMML) is unfavorable and the optimal therapy remains uncertain. Currently, allogeneic stem cell transplantation is the only known curative therapeutic option. However, the data available are limited and restricted to small retrospective series. There is even less information on the use of donor lymphocyte infusions (DLI) for this disease. We reviewed our experience of allogeneic stem cell transplantation and DLI for adults with CMML. Seventeen consecutive adults underwent allogeneic stem cell transplantation from related (n=14) or unrelated (n=3) donors. Median age was 50 years (range 26-60). Seven patients (41%) demonstrated relapse or persistent disease at a median of 6 months (range 3-55.5). Five patients underwent DLI for morphologic relapse and one for mixed donor chimerism. Two patients achieved durable complete remissions of 15 months each. The overall transplant-related mortality was 41% (n=7). With a median follow-up of 34.5 months, three patients (18%) currently remain alive and in continuous CR. The current study demonstrates a graft-versus-leukemia effect in CMML, both for allogeneic stem cell transplantation and for DLI. Nevertheless, consistent with reported experience of others, overall outcomes remain less than optimal and unpredictable.

Evaluation of a somatostatin analog in the treatment of lymphoproliferative disorders: results of a phase II North Central Cancer Treatment Group trial.

PURPOSE: Malignant cells from non-Hodgkin's lymphomas (NHL) have been shown to express the somatostatin receptor on their cell surface and most NHL are visible on somatostatin radioscintigraphy scans. This provided the rationale to conduct a phase II trial of a somatostatin analog in patients with B- and T-cell lymphoproliferative disorders. PATIENTS AND METHODS: Sixty-one patients with measurable or assessable lymphoproliferative disorders (31 stage III or IV low-grade NHL; 21 chronic lymphocytic leukemia [CLL]; and nine cutaneous T-cell NHL [CTCL]) were enrolled. Patients were treated with somatostatin 150 micrograms subcutaneously (SQ) every 8 hours for 1 month. Patients with stable or responding disease received 2 additional months of therapy; those who responded after 3 months were treated for an additional > or = 3 months. RESULTS: Sixty patients were assessable for toxicity and 56 for response. There were no complete remissions. In the low-grade NHL group, 36% (10 of 28 patients; 95% confidence interval [CI], 19% to 56%) had a partial remission. Forty-four percent (four of nine; 95% CI, 14% to 79%) of patients with CTCL had a partial response. No patients with CLL had a partial remission. Among 45 patients with stable disease or a partial remission, the mean time to progression (TTP) was 10.9 months (median, 6.2; range, 1.6 to 48.5). The drug was well tolerated, with the most common side effects being diarrhea and hyperglycemia. CONCLUSION: Somatostatin at a dose of 150 micrograms every 8 hours is well tolerated and has activity in low-grade NHL.

Early lymphocyte recovery is a predictive factor for prolonged survival after autologous hematopoietic stem cell transplantation for acute myelogenous leukemia.

Absolute lymphocyte count (ALC) recovery correlates with survival after autologous hematopoietic stem cell transplantation (AHSCT) for patients with multiple myeloma, non-Hodgkin's lymphoma, and metastatic breast cancer. The role of ALC recovery in relationship to clinical outcome after AHSCT in patients with acute myelogenous leukemia is unknown. We analyzed 45 patients who underwent AHSCT at Mayo Clinic, Rochester, Minnesota between 1990 and 2000. The ALC threshold was selected at 500 cells/microl on day 15 post-AHSCT based on our previous studies. Thirty-two females and 13 males were included in the study with a median age of 45 years (range 12-75). The median follow-up was 14 months with a maximum of 129 months. The median overall and leukemia-free survival were significantly better for the 23 patients with ALC at day 15 > or =500 cells/microl compared with 22 patients with ALC <500 cells/microl (not yet reached vs 10 months, P < 0.0009; 105 vs 9 months, P < 0.0008, respectively). In conclusion, ALC > or =500 cells/microl on day 15 post-AHSCT is associated with better survival in acute myelogenous leukemia and requires further studies.

Low-dose cytarabine maintenance therapy vs observation after remission induction in advanced acute myeloid leukemia: an Eastern Cooperative Oncology Group Trial (E5483).

The Eastern Cooperative Oncology Group (ECOG) conducted a prospective phase III study in patients with relapsed/refractory acute myeloid leukemia (AML) to evaluate whether administration of repeated courses of low-dose cytarabine (LDAC) maintenance therapy after induction of complete remission in advanced AML would improve disease-free and overall survival. Patients with AML in second/later relapse or refractory disease were first treated with a combination of high-dose cytarabine and amsacrine. Those who achieved complete remission were then randomized to observation or to receive LDAC, 10 mg/m2 subcutaneously twice a day x2 21 days every 2 months until relapse occurred. Of 86 patients eligible for randomization, 41 patients were assigned to receive LDAC and 45 patients to observation. The median disease-free survival was 7.4 months for patients assigned to LDAC compared to 3.3 months for patients receiving no additional therapy, P= 0.084. The median survival from randomization was 10.9 months and 7.0 months for patients receiving LDAC maintenance chemotherapy and observation, respectively (P= 0.615). The data from this study suggest that LDAC maintenance therapy given to patients with advanced AML who achieve complete remission can increase disease-free survival compared to observation, but does not improve overall survival. Nevertheless, because of the ineffectiveness and toxicity of intensive post-remission chemotherapy in this circumstance, LDAC maintenance therapy, a tolerable outpatient regimen, offers the potential for improved quality of life.

Pericarditis induced by high-dose cytarabine therapy.

Pericarditis with tamponade developed in a patient treated with high-dose cytarabine for acute lymphocytic leukemia. Evidence suggests that this was a direct complication of his treatment.

Monoclonal cryoglobulinemia with high thermal insolubility.

It is generally believed that the severity of symptoms associated with cryoglobulinemia is a function of the concentration of the abnormal protein in the plasma. We have seen two patients with a small monoclonal cryoglobulin (type I) of ess than 2 g/dl with dramatic symptoms when exposed to minimal lowering of the temperature. Both patients had a monoclonal protein that precipitated in vitro at temperatures higher than 25 degrees C. We have found only seven additional case reports in the literature which were similar to ours. We wish to bring attention to this rare problem and discuss treatment.

Hemorrhagic cystitis complicating bone marrow transplantation.

Hemorrhagic cystitis is a potentially serious complication of high-dose cyclophosphamide therapy administered before bone marrow transplantation. As standard practice at our institution, patients who are scheduled to receive a bone marrow transplant are treated prophylactically with forced hydration and bladder irrigation. In an attempt to obviate the inconvenience of bladder irrigation, we conducted a feasibility trial of uroprophylaxis with mesna, which neutralizes the hepatic metabolite of cyclophosphamide that causes hemorrhagic cystitis. Of 97 patients who received standard prophylaxis, 4 had symptomatic hemorrhagic cystitis. In contrast, two of four consecutive patients who received mesna uroprophylaxis before allogeneic bone marrow transplantation had severe hemorrhagic cystitis for at least 2 weeks. Because of this suboptimal result, we resumed the use of bladder irrigation and forced hydration to minimize the risk of hemorrhagic cystitis.

Reinduction chemotherapy for acute nonlymphocytic leukemia.

Twenty-four patients who had a relapse after successful treatment of acute nonlymphocytic leukemia were re-treated with a chemotherapeutic program similar to that which produced the initial remission. Eight of the nine patients who achieved a second remission had received a three-drug reinduction regimen consisting of cytosine arabinoside, an anthracycline, and 6-thioguanine. An increased duration of initial remission before relapse (more than 26 weeks) predicted a greater likelihood of achieving a second remission.

Outcome of recipients of bone marrow transplants who require intensive-care unit support.

To determine the outcome and prognostic factors associated with bone marrow transplantation (BMT), we reviewed the clinical course of 35 adult recipients of such a transplant who were admitted to our intensive-care unit (ICU). This constituted 24% of patients who underwent BMT for treatment of hematologic disorders during the study period. The reasons for admission to the ICU were postsurgical care in 5, respiratory failure in 25, shock in 4, and renal failure in 1. The in-hospital mortality was 20% for the postsurgical patients and 87% for the others. None of the postsurgical patients required mechanical ventilation, whereas 90% of the others did, and the associated mortality was 93%. Infection was the cause of the respiratory failure in all but 3 of the 25 patients and was associated with 95% mortality. Complications that involved multiple organs increased the mortality to 100%. No significant differences were found in age, sex, type of BMT, serologic tests for cytomegalovirus, history of graft-versus-host disease, conditioning regimen for BMT, and duration of stay in the ICU and the hospital between survivors and nonsurvivors. The APACHE II (acute physiology and chronic health evaluation) prognostic scoring system underestimated mortality and had no correlation with the duration of stay in the ICU or the hospital. Vasopressors, total parenteral nutrition, and transfusion of blood components in the ICU had no influence on the outcome. Open-lung biopsy was helpful in making specific diagnoses, and pulmonary artery catheters were used in most patients to guide therapy but did not improve survival.(ABSTRACT TRUNCATED AT 250 WORDS)

Cytogenetic and molecular detection of residual leukemic cells after allogeneic bone marrow transplantation in chronic granulocytic leukemia.

Allogeneic bone marrow transplantation (BMT) is a therapeutic modality with a curative potential for chronic granulocytic leukemia. Approximately 20% of patients have a hematologic relapse after BMT. The frequency of cytogenetic or molecular relapse (or both), despite hematologic remission, is reportedly higher. We performed allogeneic BMT in 32 patients with chronic granulocytic leukemia by using unmanipulated donor marrow and a conditioning regimen that consisted of cyclophosphamide and total-body irradiation. Of these 32 patients, 23 had cytogenetic studies after BMT. Seven of these patients had cytogenetically detectable Philadelphia chromosomes some time after BMT, during hematologic remission. The Philadelphia chromosome was detected transiently in two patients, and the fraction of abnormal metaphases exceeded 25% in three patients. None of the patients with negative results of cytogenetic studies or with the presence of the Philadelphia chromosome in less than 25% of analyzed metaphases had a clinical relapse, whereas two of the three patients with more than 25% abnormal metaphases had clinical relapses. Our results suggest that the detection of more than 25% abnormal metaphases during cytogenetic studies for chronic granulocytic leukemia after BMT may imply an incipient clinical relapse. We review the current literature that discusses isolated cytogenetic or molecular relapses of chronic granulocytic leukemia after BMT.

Mayo Clinic experience with allogeneic and syngeneic bone marrow transplantation, 1982 through 1990.

Between April 1982 and July 1990, 101 patients underwent allogeneic or syngeneic bone marrow transplantation at the Mayo Clinic. This patient population consisted of 30 with acute nonlymphocytic leukemia, 25 with acute lymphoblastic leukemia, 29 with chronic granulocytic leukemia, and 17 with other diseases (aplastic anemia in 7, myelodysplastic syndrome in 5, and lymphoma in 5). The results achieved in our patients who underwent transplantation in first complete remission of both acute nonlymphocytic leukemia and acute lymphoblastic leukemia compare favorably with previously reported results. Only 1 of 15 patients (7%) with acute nonlymphocytic leukemia and 2 of 8 patients (25%) with acute lymphoblastic leukemia who underwent transplantation in first complete remission had a relapse. Thus, we recommend early bone marrow transplantation during initial complete remission for patients with either of these disorders who have adverse prognostic factors. In contrast, of 12 patients with either acute nonlymphocytic leukemia or acute lymphoblastic leukemia who underwent transplantation during relapse, 11 died within 6 months. Therefore, such patients should be offered new experimental treatments. Our patients with chronic granulocytic leukemia fared better when they underwent transplantation early during the course of their disease rather than during the accelerated or blast phase. Prospective studies are needed to determine the best approach in these patients.

Amifostine alone and in combination with erythropoietin for the treatment of favorable myelodysplastic syndrome.

Ten anemic patients with favorable myelodysplastic syndrome (MDS) were first treated with two 5-week courses of amifostine alone (each course consisted of 200 mg/m(2) of the drug given intravenously three times a week for 3 weeks), followed by an additional two courses combined with subcutaneous erythropoietin (EPO) (150 U/kg, three times a week for 8 weeks). The study patients either had previously failed to respond to treatment with EPO or had pretreatment serum EPO levels of more than 100 mU/ml. None of the patients experienced a complete or partial response in anemia or other cytopenias. We conclude that amifostine alone or in combination with EPO has limited therapeutic activity in MDS.

Treatment of unfavorable myelodysplastic syndrome with all-trans-retinoic acid and subcutaneous Ara C.

Thirty patients with high-risk myelodysplastic syndrome, defined as > 5% bone marrow blasts, were treated with a combination of oral all-trans-retinoic acid (45 mg/m2 daily) and subcutaneous AraC (10 mg/m2) on days 1-14 of each 28-35 day cycle repeated for 2-6 cycles. Complete remission lasting 9, 12, and 15 months was achieved in three patients. Partial and minor response did not translate into meaningful clinical improvement, like complete responders. Overall incidence of leukemia transformation and survival of this cohort of patients was no different from the expected outcome for a group of patients with similar characteristics.

Development of hepatic veno-occlusive disease after Mylotarg infusion for relapsed acute myeloid leukemia.

Mylotarg (gemtuzumab zogamicin) is a conjugated monoclonal antibody that has recently become available for use in patients with relapsing or refractory acute myeloid leukemia. Reversible hepatotoxicity is common after administration. We describe the first report of hepatic veno-occlusive disease (HVOD) developing after Mylotarg infusion in a patient who underwent hematopoietic stem cell transplantation 8 months earlier. Certain antineoplastic agents have been implicated as a cause of HVOD, but the disease is most commonly seen within 30 days after hematopoietic stem cell transplantation. The possible association between Mylotarg infusion and HVOD is discussed.

Nodular lesions of monocytic component in myelodysplastic syndrome.

We report 4 unusual cases of myelodysplastic syndrome with distinct persistent nodular lesions noted on serial bone marrow examinations, even during remission. The lesions were predominantly composed of immature monocytes that stained positively for CD68. Trisomy 9 and 11 were demonstrated in the cells of the nodular lesions and surrounding marrow of 1 patient, indicating the same clonal origin. Evaluation of p53 glycoprotein, retinoblastoma protein (pRb), proliferation-related protein (Ki-67), multiple drug-resistant enzyme glutathione-S-transferase pi, and topoisomerase IIalpha (Topo IIalpha) revealed decreased topoisomerase expression within the nodular lesions compared with the surrounding marrow and absence of Ki-67 antigen within nodular lesions. Most cells in the lesion were not in a proliferative cycle, with very low expression of Topo IIalpha, which may explain the apparent drug resistance of these nodular lesions.

Deletions of chromosome 13 in malignant hematologic disorders.

Thirteen patients with a hematologic disorder and an interstitial deletion of part of a chromosome #13 were evaluated to determine if any specific clinical manifestations are associated with these cytogenetic anomalies. Our results suggest that these anomalies occur in approximately 1.7% of patients with a chromosomally abnormal clone and a hematologic disorder. They may occur as the sole chromosome anomaly (8 of our patients) or with other abnormalities (5 of our patients). The breakpoints are not always the same, but band 13q14 always seems to be lost. At the time of chromosome analysis, 5 patients had a history of myelofibrosis or agnogenic myeloid metaplasia, 2 had acute nonlymphocytic leukemia, 2 had a myelodysplastic syndrome, one had polycythemia vera, one had sideroblastic anemia, one had acute lymphocytic leukemia, and one had an undifferentiated myeloproliferative disorder.