Michela Montagna

Alemtuzumab As Consolidation After a Response to Fludarabine Is Effective in Purging Residual Disease in Patients With Chronic Lymphocytic Leukemia

PURPOSE Treatment with alemtuzumab has resulted in negative responses for minimal residual disease (MRD) in patients with chronic lymphocytic leukemia (CLL). In a prior analysis we demonstrated that it is possible to achieved MRD negativity, as assessed by polyclonality of immunoglobulin heavy chain after consolidation with alemtuzumab. This phase II study evaluated 34 patients with CLL who received alemtuzumab consolidation in an effort to improve the quality of their response to fludarabine-based induction. Subsequent peripheral blood stem-cell (PBSC) collection and transplantation, tolerability, and pharmacokinetics also were assessed. PATIENTS AND METHODS Thirty-four patients younger than 65 years who had a clinical response to fludarabine-based induction therapy received alemtuzumab 10 mg subcutaneously three times per week for 6 weeks. PBSCs were collected after mobilization with cytarabine and granulocyte colony-stimulating factor. Blood samples for pharmacokinetics study were taken between days 1 and 31. RESULTS The complete response rate improved from 35% after fludarabine induction to 79.4% after alemtuzumab consolidation, including 19 patients (56%) who achieved MRD negativity. The most common adverse events were injection-site reactions and fever. Cytomegalovirus reactivation occurred in 18 patients, all of whom were successfully treated with oral ganciclovir. PBSC collection was successful in 24 (92%) of 26 patients, and 18 patients underwent autologous PBSC transplantation. Alemtuzumab plasma concentrations increased gradually during the first 2 weeks and accumulated more rapidly thereafter. CONCLUSION Subcutaneously administered alemtuzumab was effective, safe, and well tolerated as consolidation therapy in patients with CLL who responded to fludarabine induction therapy. Subsequent PBSCT was feasible thereafter.

Rituximab in Children with Resistant Idiopathic Nephrotic Syndrome

Idiopathic nephrotic syndrome resistant to standard treatments remains a therapeutic dilemma in pediatric nephrology. To test whether the anti-CD20 monoclonal antibody rituximab may benefit these patients, we conducted an open-label, randomized, controlled trial in 31 children with idiopathic nephrotic syndrome unresponsive to the combination of calcineurin inhibitors and prednisone. All children continued prednisone and calcineurin inhibitors at the doses prescribed before enrollment, and one treatment group received two doses of rituximab (375 mg/m(2) intravenously) as add-on therapy. The mean age was 8 years (range, 2-16 years). Rituximab did not reduce proteinuria at 3 months (change, -12% [95% confidence interval, -73% to 110%]; P=0.77 in analysis of covariance model adjusted for baseline proteinuria). Additional adjustment for previous remission and interaction terms (treatment by baseline proteinuria and treatment by previous remission) did not change the results. In conclusion, these data do not support the addition of rituximab to prednisone and calcineurin inhibitors in children with resistant idiopathic nephrotic syndrome.

Lower dose rituximab is active in adults patients with idiopathic thrombocytopenic purpura

Rituximab 375 mg/m2 weekly for four weeks has significant activity in patients with immune thrombocytopenia. We evaluated the activity of lower dose rituximab (100 mg iv weekly for 4 weeks) in 28 adults with idiopathic thrombocytopenic purpura. Overall (platelet count > 50×109/L) and complete responses (platelet count > 100×109/L) were achieved in 21/28 (75%) and 12/28 (43%) patients respectively. The median time to response and time to complete response were 31 and 44 days respectively. After a median follow-up of 11 months (range 3–18), 7/21 (33%) patients relapsed and 3 needed further treatments. In patients with idiopathic thrombocytopenic purpura, lower dose rituximab seems to show similar activity to standard dose.

Antiretrovirals: Simultaneous determination of five protease inhibitors and three nonnucleoside transcriptase inhibitors in human plasma by a rapid high-performance liquid chromatography-mass spectrometry assay

An analytical technique using liquid chromatography (LC) coupled with electrospray–mass spectrometry (ESI–MS) has been developed for the simultaneous determination of five protease inhibitors (PIs): saquinavir, indinavir, ritonavir, nelfinavir, and amprenavir; and three non-nucleoside reverse transcriptase inhibitors (NNRTIs): nevirapine, delavirdine, and efavirenz, in human plasma. This assay allows the elution and identification of these drugs in a single run (10 minutes) using a linear gradient with water and acetonitrile. The procedure involves liquid–liquid extraction. High-performance liquid chromatography (HPLC) separation was achieved on a C18 reversed-phase column, with a linear gradient elution followed by mass spectrometry detection. The calibration curves, obtained by automatic process peak area integration, show a good linearity in a range of concentrations between 20 and 10,000 ng/mL (40–10,000 ng/mL for efavirenz). The limit of detection was approximately 10 ng/mL for seven drugs (25 ng/mL for efavirenz). The coefficients of variation (CV) were always less than 15% for both intraday and interday precision for each compound. The recovery of the eight drugs ranged from 88.5% to 100%. This novel LC/ESI–MS assay provides an excellent method for simultaneous quantitative monitoring of different components of the highly active antiretroviral treatments (HAARTs) in patients treated simultaneously with PIs and NNRTIs, and it has been successfully applied to therapeutic drug monitoring and pharmacokinetic studies.

Pharmacokinetic behavior of rituximab: a study of different schedules of administration for heterogeneous clinical settings.

This study was designed to report the pharmacokinetic behavior of Rituximab in patients affected with different diseases and treated with different schedules of administration. A low tumor burden was a common feature of all patients (N = 48) included in our study, whereas the timing of Rituximab administration varied from weekly (groups 1, 2, 3) to monthly (group 4). Group 1 included patients with follicular lymphoma treated with 4 weekly doses of Rituximab after first-line chemotherapy with CHOP. At the start of Rituximab, patients were in partial or complete clinical response but showed persistence of disease at molecular level (bcl-2-positive) in bone marrow and/or peripheral blood. Patients in group 2 had autoimmune disorders and Rituximab was given to act on B-cells, interfering with their production of autoantibodies. In patients with amyloidosis (group 3), Rituximab was given to kill progenitor B-cells of the small clone terminating in amyloid-producing plasma cells. In groups 2 and 3, the target of monoclonal antibody was a population of small B cells, which make an intrinsic feature of the diseases. Group 4 included patients with relapsed or refractory follicular and mantle cell lymphoma who underwent a salvage program of immunochemotherapy, purging in vivo and autotransplant: the first of the six planned doses of Rituximab was administered after a debulking phase with a third-generation regimen, such as VACOP-B. An enzyme-linked immunoassay (ELISA) developed and validated in our laboratory was used for the pharmacokinetic study. Rituximab disposition was characterized by a 2-exponential decay, with a long elimination half-life of approximately 3 weeks (range, 248-859 hours). The total systemic clearance ranged between 3.1 and 11.9 mL/hr/m2. After 4 weekly infusions, Rituximab concentration was ∼2.5 μg/mL, which is approximately 85% of the steady-state level. Steady-state plasma concentrations of Rituximab were reached after 6 to 8 weekly infusions. The adopted pharmacokinetic model (2-compartment open model) seems to provide the best fit of Rituximab disposition both during and after treatment, even when different schedules of drug administration are used. Because several studies reported an association between response and serum Rituximab concentrations, a treatment based on a pharmacokinetic model may be useful for predicting the desired drug concentration.

Comparison of the Plasma Pharmacokinetics of Lamivudine During Twice and Once Daily Administration in Patients with HIV

ObjectiveTo compare the plasma pharmacokinetics of lamivudine 150mg twice daily and 300mg once daily in patients with HIV-1 infection.DesignNonblind, sequential, pharmacokinetic study.Participants13 patients with HIV-1 infection (median age 36 years).MethodsPatients were tested during twice daily and then once daily regimens of lamivudine. In both regimens, the total daily dose of lamivudine was identical (300 mg/day). Blood samples for pharmacokinetic analysis were taken over a 12-hour period after ≥7 days of twice daily administration, and again over a 24-hour period after 7 days of once daily administration,.Results12 patients completed the study. Lamivudine pharmacokinetic parameters (mean ± SD) after administration of 150mg twice daily were: peak plasma concentration (Cmax) 2077 ± 816 μg/L; trough plasma concentration (Cmin) 332 ±219 μg/L; elimination half-life (t½β) 6.1 ± 1.9h; time to Cmax (tmax) 1.6 ± 0.7h; average concentration over the dosage interval (Cav) 711 ± 269 μg/L; and area under the concentration-time curve (AUC) over 2 dosage intervals (24h) 17 085 ± 6464 μg □h/L. Corresponding values after administration of 300mg once daily were: Cmax3461 ± 854 μg/L; Cmin 146 ± 87 μg/L; t½β 7.9 ± 3.4h; tmax2.2 ± 1.3h; Cav 705 ± 177 μg/L; and AUC over 1 dosage interval (24h) 16 644 ± 4150 μg □ h/L. Statistical analysis showed a significant difference (p < 0.05) between the 2 schedules for Cmax and Cmin values, whereas no significant differences emerged for the other parameters.ConclusionsOnce daily lamivudine leads to a similar exposure in plasma as twice daily administration of the same total daily dose. Since once daily administration may result in improved compliance, these results provide the pharmacokinetic basis for using lamivudine in a once daily regimen. Randomised clinical studies are needed to confirm this pharmacokinetic finding.

Relationship between pharmacokinetic profile of subcutaneously administered alemtuzumab and clinical response in patients with chronic lymphocytic leukemia

Alemtuzumab serum levels and clinical response after subcutaneous administration (10 mg 3 times/week for six weeks) have been explored in 29 chronic lymphocytic leukemia patients receiving the monoclonal antibody as consolidation. Serum concentrations after each administration gradually increased during the first week and more markedly during weeks 2 and 3, approaching the steady-state at week 6. Absorption continued slowly through the tissues for about 2–3 weeks after the last administration, starting to decrease thereafter. Difference between Responders and Non-responders was statistically significant: maximal concentration (Cmax) was 1.69 μg/mL vs. 0.44 μg/mL; concentration before subcutaneous administration (Cpre-dose) on day 15 was 0.7 vs. 0.21 μg/mL, area under curve (AUC0−12h) was 11.09 vs. 2.26 μg x h/mL for Responders and Non-responders, respectively. Higher systemic exposure to alemtuzumab correlated with a better clinical response and minimal residual disease. Results suggest that an adjusted schedule according to serum level could improve clinical outcome of patients receiving subcutaneous alemtuzumab.

A new sensitive enzyme-linked immunosorbent assay (ELISA) for Alemtuzumab determination: development, validation and application.

Alemtuzumab is a humanized (IgG,) rat monoclonal antibody to CD52 antigen and is currently used in the treatment of chronic lymphocytic leukemia (CLL) and other CD52-positive lymphoproliferative disorders. Various techniques have been developed to measure Alemtuzumab levels in human serum/plasma. The authors report on the validation of a very sensitive enzyme-linked immunosorbent assay (ELISA) to measure serum concentrations of the humanized IgG, using a rabbit polyclonal antibody specifically produced against the rat sequence of Alemtuzumab after papain digestion. The assay was successfully applied to test the serum samples of patients with B-lymphocyte CLL who received Alemtuzumab subcutaneously. This ELISA assay could be easily used to determine human serum levels of Alemtuzumab pre- and post-treatment to optimize dosing and scheduling and to study the relationship between dose and clinical response.

Plasma alemtuzumab levels in patients with chronic lymphocytic leukemia treated with alemtuzumab combined with chemotherapy reflect the efficacy of the treatment: a hypothesis.

Abstract In the HOVON68 trial comparing subcutaneous low-dose alemtuzumab (LD-A) used together with fludarabine (F) and cyclophosphamide (C) with FC alone in high-risk chronic lymphocytic leukemia (CLL), LD-AFC resulted in significantly more clinical and molecular responses than FC, but also in more opportunistic infections. In a subgroup analysis of alemtuzumab trough levels during treatment by a sensitive enzyme-linked immunosorbent assay (ELISA) method, detectable levels were found in 4/6 complete and 0/3 partial responders. A relationship between alemtuzumab plasma levels, response and duration of lymphocytopenia was evident. We hypothesize that following combination therapy, the response may not be a function of the alemtuzumab levels, but the opposite, that plasma alemtuzumab levels are a function of the efficacy of the entire treatment, and the fewer leukemic target cells that are remaining, the higher are the levels of plasma alemtuzumab. This concept may well provide a guide for alemtuzumab dosage in future trials.

A new enzyme-linked immunosorbent assay for a total anti-T lymphocyte globulin determination: Development, analytical validation, and clinical applications

Background: Anti-T lymphocyte globulin (ATLG) modulates the alloreactivity of T lymphocytes, reducing the risk of immunological posttransplant complications, in particular rejection and graft-versus-host disease, after allogeneic hematopoietic stem cell transplantation (HSCT). We developed and validated a new enzyme-linked immunosorbent assay (ELISA) method to measure serum levels of total ATLG and evaluate the pharmacokinetics (PK) of the drug in children with &bgr;-Thalassemia, receiving allogeneic HSCT. Methods: Diluted serum samples were incubated with Goat-anti-Rabbit IgG antibody coated on a microtiter plate and then, with Goat-anti-Human IgG labeled with horseradish peroxidase. After incubation and washings, substrate solution was added and absorbance was read at 492 nm. ATLG concentrations in samples were determined by interpolation from a standard curve (range: 200–0.095 ng/mL), prepared by diluting a known amount of ATLG in phosphate-buffered saline (PBS). Low, medium, and high-quality control concentrations were 1.56, 6.25, and 25 ng/mL, respectively. This method was developed and validated within the acceptance criteria in compliance with the Guidelines for a biological method validation: the sensitivity of the method was 0.095 ng/mL. We analyzed serum samples from 14 children with &bgr;-Thalassemia who received ATLG (Grafalon) at a dose of 10 mg/kg administered as intravenous (IV) infusion on days −5, −4, and −3 before HSCT (day 0). Blood sampling for PK evaluation was performed on days −5, −4, and −3 before and after drug infusion; and then from day −2 to +56. Results: The median total ATLG levels pre-IVand post-IV were 0 and 118 mcg/mL on day −5; 85.9 and 199.2 mcg/mL on day −4; 153 and 270.9 mcg/mL on day −3, respectively. The median PK values of CL was 0.0029 (range: 0.0028–0.0057) L·kg−1·d−1, Vd was 0.088 (range: 0.025–0.448) L/kg and t1/2 was 20.2 (range: 5.8–50.2) days. Conclusions: These data suggest that given the marked interindividual variability of total ATLG disposition, the development of a validated ELISA method and the possibility to measure PK parameters in paediatric populations are essential steps to optimize drug therapeutic regimens.