Balancing cancer immunotherapy and immune-related adverse events: The emerging role of regulatory T cells.

Advances in our understanding οf tumor immunity have prompted a paradigm shift in oncology, with the emergence of immunotherapy, where therapeutic agents are used to target immune cells rather than cancer cells. A real breakthrough in the field of immunotherapy came with the use of immune checkpoint inhibitors (ICI), namely antagonistic antibodies that block key immune regulatory molecules (checkpoint molecules), such as cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4), programmed cell death protein (PD-1) and its ligand PD-L1, that under physiologic conditions suppress T cell effector function. However, despite the enormous success, a significant proportion of patients do not respond, while responses are frequently accompanied by life-threatening autoimmune related adverse events (irAEs). A major impediment in the effectiveness of ICI immunotherapy is the tumoral resistance, which is dependent on the immunosuppressive nature of tumor microenvironment (TME). Regulatory T cells (Tregs) are among the most abundant suppressive cells in the TME and their presence has been correlated with tumor progression, invasiveness as well as metastasis. Tregs are characterized by the expression of the transcription factor Foxp3 and various mechanisms ranging from cell-to-cell contact to secretion of inhibitory molecules have been implicated in their function. Notably, Tregs amply express most of the checkpoint molecules such as CTLA4, PD1 and LAG3 and therefore represent a direct target of ICI immunotherapy. Taking into consideration the critical role of Tregs in maintenance of immune homeostasis and avoidance of autoimmunity it is plausible that targeting of Tregs by ICI immunotherapy results in the development of irAEs. Since the use of ICI becomes common, and new immune checkpoint molecules are currently under clinical trials for the treatment of cancer, the occurrence of irAEs is expected to dramatically rise. Herein we review the current literature focusing on the role of Tregs in cancer evolution, ICI response and development of irAEs. Unraveling the complex mechanisms that hinder the tumor immune surveillance and in particular how ICI immunotherapy imprint on Treg activities to promote cancer regression while avoid development of irAEs, will empower the design of novel immunotherapeutic modalities in cancer with increased efficacy and diminished adverse events.

Alemtuzumab induction in renal transplantation.

BACKGROUND: There are few comparisons of antibody induction therapy allowing early glucocorticoid withdrawal in renal-transplant recipients. The purpose of the present study was to compare induction therapy involving alemtuzumab with the most commonly used induction regimens in patient populations at either high immunologic risk or low immunologic risk. METHODS: In this prospective study, we randomly assigned patients to receive alemtuzumab or conventional induction therapy (basiliximab or rabbit antithymocyte globulin). Patients were stratified according to acute rejection risk, with a high risk defined by a repeat transplant, a peak or current value of panel-reactive antibodies of 20% or more, or black race. The 139 high-risk patients received alemtuzumab (one dose of 30 mg, in 70 patients) or rabbit antithymocyte globulin (a total of 6 mg per kilogram of body weight given over 4 days, in 69 patients). The 335 low-risk patients received alemtuzumab (one dose of 30 mg, in 164 patients) or basiliximab (a total of 40 mg over 4 days, in 171 patients). All patients received tacrolimus and mycophenolate mofetil and underwent a 5-day glucocorticoid taper in a regimen of early steroid withdrawal. The primary end point was biopsy-confirmed acute rejection at 6 months and 12 months. Patients were followed for 3 years for safety and efficacy end points. RESULTS: The rate of biopsy-confirmed acute rejection was significantly lower in the alemtuzumab group than in the conventional-therapy group at both 6 months (3% vs. 15%, P<0.001) and 12 months (5% vs. 17%, P<0.001). At 3 years, the rate of biopsy-confirmed acute rejection in low-risk patients was lower with alemtuzumab than with basiliximab (10% vs. 22%, P=0.003), but among high-risk patients, no significant difference was seen between alemtuzumab and rabbit antithymocyte globulin (18% vs. 15%, P=0.63). Adverse-event rates were similar among all four treatment groups. CONCLUSIONS: By the first year after transplantation, biopsy-confirmed acute rejection was less frequent with alemtuzumab than with conventional therapy. The apparent superiority of alemtuzumab with respect to early biopsy-confirmed acute rejection was restricted to patients at low risk for transplant rejection; among high-risk patients, alemtuzumab and rabbit antithymocyte globulin had similar efficacy. (Funded by Astellas Pharma Global Development; INTAC ClinicalTrials.gov number, NCT00113269.).

Alemtuzumab therapy in T-cell prolymphocytic leukemia: comparing efficacy in a series treated intravenously and a study piloting the subcutaneous route.

Intravenous alemtuzumab is an effective and well-tolerated treatment for T-cell prolymphocytic leukemia (T-PLL). Alemtuzumab given intravenously as first-line treatment in 32 patients resulted in an overall response rate of 91% with 81% complete responses. Studies in B-cell chronic lymphocytic leukemia have shown subcutaneous alemtuzumab to be equally as effective as intravenous alemtuzumab. The UKCLL05 pilot study examined the efficacy and toxicity of this more convenient method of administration in 9 previously untreated patients with T-PLL. Only 3 of 9 patients (33%) responded to treatment. Furthermore, 2 of 9 patients (22%) died while on treatment. Recruitment was terminated because of these poor results. After rescue therapy with intravenous alemtuzumab and/or pentostatin, median progression-free survival and overall survival were similar to the intravenous group. Alemtuzumab delivered intravenously, but not subcutaneously, remains the treatment of choice for previously untreated T-PLL.

An open-label, pilot study of fludarabine, cyclophosphamide, and alemtuzumab in relapsed/refractory patients with B-cell chronic lymphocytic leukemia.

Although combination regimens have improved outcomes over monotherapy in chronic lymphocytic leukemia (CLL), patients eventually relapse. Combined fludarabine, cyclophosphamide, and monoclonal anti-CD52 antibody alemtuzumab (FCC) provided synergistic cytotoxicity with effective clearing of minimal residual disease. This phase 2 study determined FCC efficacy and safety in relapsed/refractory CD52(+) B-CLL after ≥ 1 line of treatment. From January 2005 through June 2008, up to 6 courses of oral fludarabine 40 mg/m² per day, oral cyclophosphamide 250 mg/m² per day, and subcutaneous alemtuzumab (Mab-Campath) 10 mg (increased to 20 mg after first 10-patient cohort) were administered days 1 to 3 every 28 days. The primary objective was overall response rate (ORR); secondary objectives included response duration, time to disease progression, and safety and tolerability. ORR was 67% in 43 patients; 30% achieved complete response. ORR significantly improved with 1 versus ≥ 2 prior therapies (P = .018), and without versus with previous monoclonal antibody treatment (P = .003). Median progression-free survival was 24.4 months, not reached in patients achieving complete response. Median overall survival was 33.6 months. Myelosuppression was the most common adverse event, with a low percentage of cytomegalovirus reactivations and manageable infections. However, close vigilance of opportunistic infections is warranted. FCC provides effective immunotherapy in relapsed/refractory CLL, including in patients with poor-risk prognostic factors.

Cyclophosphamide, fludarabine, alemtuzumab, and rituximab as salvage therapy for heavily pretreated patients with chronic lymphocytic leukemia.

Patients with relapsed chronic lymphocytic leukemia (CLL) and high-risk features, such as fludarabine refractoriness, complex karyotype, or abnormalities of chromosome 17p, experience poor outcomes after standard fludaradine-based regimens. Alemtuzumab is a chimeric CD52 monoclonal antibody with activity in CLL patients with fludarabine-refractory disease and 17p deletion. We report the outcome for 80 relapsed or refractory patients with CLL enrolled in a phase 2 study of cyclophosphamide, fludarabine, alemtuzumab, and rituximab (CFAR). All patients were assessed for response and progression according to the 1996 CLL-working group criteria. For the intention-to-treat analysis, the overall response rate was 65%, including 29% complete response. The estimated progression-free survival was 10.6 months and median overall survival was 16.7 months. Although we noted higher complete response in high-risk patients after CFAR compared with a similar population who had received fludarabine, cyclophosphamide, and rituximab as salvage therapy, there was no significant improvement in progression-free survival and overall survival appeared worse. CFAR was associated with a high rate of infectious complications with 37 patients (46%) experiencing a serious infection during therapy and 28% of evaluable patients experiencing late serious infections. Although CFAR produced good response rates in this highly pretreated high-risk group of patients, there was no benefit in survival outcomes.

A distinctive form of immune thrombocytopenia in a phase 2 study of alemtuzumab for the treatment of relapsing-remitting multiple sclerosis.

In a phase 2 clinical trial of annual alemtuzumab for treatment of relapsing-remitting multiple sclerosis, 6 of 216 patients (2.8%) developed immune thrombocytopenia (ITP). Over mean follow-up of 4.5 years, the incidence rate of ITP was 6.2 (95% confidence interval, 2.3-13.3) per 1000 person-years. Median times from initial and last alemtuzumab exposure to ITP diagnosis were 24.5 and 10.5 months, respectively. Five patients developed severe thrombocytopenia. Four were symptomatic, including fatal intracranial hemorrhage in the index case. Four patients received standard first-line ITP therapy, all of whom responded to treatment within 1 week. All 5 surviving patients achieved complete remission and remained in complete remission without need for ongoing ITP therapy for a median duration of 34 months at last follow-up. A monitoring plan for the early detection of ITP, implemented after presentation of the index case, identified all 5 subsequent cases before serious hemorrhagic morbidity or mortality occurred. In conclusion, we describe a distinctive form of ITP associated with alemtuzumab treatment characterized by delayed presentation after drug exposure, responsiveness to conventional ITP therapies, and prolonged remission. Clinicians should maintain a high level of vigilance and consider routine monitoring for ITP in patients treated with this agent. This trial was registered at www.clinicaltrials.gov as #NCT00050778.

Frontline chemoimmunotherapy with fludarabine, cyclophosphamide, alemtuzumab, and rituximab for high-risk chronic lymphocytic leukemia.

Frontline chemoimmunotherapy with fludarabine, cyclophosphamide, and rituximab (FCR) is associated with superior overall survival (OS) for patients with chronic lymphocytic leukemia (CLL). Alemtuzumab (A) was added to FCR (CFAR) in a phase 2 trial for high-risk untreated patients < 70 years with serum ß-2 microglobulin (ß2M) ≥ 4 mg/L. Sixty patients were enrolled; median age was 59 years (range, 42-69); 75% were male; median ß2M was 5.1 mg/L (range, 4-11.6); and 51% were Rai III-IV. Complete remission (CR) was achieved in 70%, partial remission (PR) in 18%, nodular PR in 3%, for an overall response of 92%. Of 14 patients with 17p deletion, CR was achieved by 8 (57%). Of 57 BM samples evaluated by 3-color flow cytometry at the end of treatment, 41 (72%) were negative for residual disease. Grade 3-4 neutropenia and thrombocytopenia occurred with 33% and 13% courses, respectively. The median progression-free survival was 38 months and median OS was not reached. In conclusion, CFAR is an active frontline regimen for high-risk CLL. Response rates and survival are comparable with historic high-risk FCR-treated patients. CFAR may be a useful frontline regimen to achieve CR in patients with 17p deletion before allogeneic stem cell transplantation.

Long term lymphocyte reconstitution after alemtuzumab treatment of multiple sclerosis.

BACKGROUND: Alemtuzumab is a lymphocyte depleting monoclonal antibody that has demonstrated superior efficacy over interferon ß-1a for relapsing-remitting multiple sclerosis (MS), and is currently under investigation in phase 3 trials. One unresolved issue is the duration and significance of the lymphopenia induced. The long term effects on lymphocyte reconstitution of a single course, and the consequences that this has on disability, morbidity, mortality and autoimmunity, were examined. METHODS: The lymphocyte reconstitution (n=36; 384 person years) and crude safety data (n=37; 447 person years) are reported for the first patients with progressive MS to receive alemtuzumab (1991-1997). Reconstitution time was expressed as a geometric mean or, when a non-negligible number of individuals failed to recover, as a median using survival analysis. RESULTS: Geometric mean recovery time (GMRT) of total lymphocyte counts to the lower limit of the normal range (LLN; ≥1.0×10(9) cells/l) was 12.7 months (95% CI 8.8 to 18.2 months). For B cells, GMRT to LLN (≥0.1×10(9)/l) was 7.1 months (95% CI 5.3 to 9.5); median recovery times for CD8 (LLN ≥0.2×10(9) cells/l) and CD4 lymphocytes (LLN ≥0.4×10(9) cells/l) were 20 months and 35 months, respectively. However, CD8 and CD4 counts recovered to baseline levels in only 30% and 21% of patients, respectively. No infective safety concerns arose during 447 person years of follow-up. CONCLUSIONS: Lymphocyte counts recovered to LLN after a single course of alemtuzumab in approximately 8 months (B cells) and 3 years (T cell subsets), but usually did not recover to baseline values. However, this long lasting lymphopenia in patients with a previously normal immune system was not associated with an increased risk of serious opportunistic infection.

Alemtuzumab vs. interferon beta-1a in early multiple sclerosis.

BACKGROUND: Alemtuzumab, a humanized monoclonal antibody that targets CD52 on lymphocytes and monocytes, may be an effective treatment for early multiple sclerosis. METHODS: In this phase 2, randomized, blinded trial involving previously untreated, early, relapsing-remitting multiple sclerosis, we assigned 334 patients with scores of 3.0 or less on the Expanded Disability Status Scale and a disease duration of 3 years or less to receive either subcutaneous interferon beta-1a (at a dose of 44 microg) three times per week or annual intravenous cycles of alemtuzumab (at a dose of either 12 mg or 24 mg per day) for 36 months. In September 2005, alemtuzumab therapy was suspended after immune thrombocytopenic purpura developed in three patients, one of whom died. Treatment with interferon beta-1a continued throughout the study. RESULTS: Alemtuzumab significantly reduced the rate of sustained accumulation of disability, as compared with interferon beta-1a (9.0% vs. 26.2%; hazard ratio, 0.29; 95% confidence interval [CI], 0.16 to 0.54; P<0.001) and the annualized rate of relapse (0.10 vs. 0.36; hazard ratio, 0.26; 95% CI, 0.16 to 0.41; P<0.001). The mean disability score on a 10-point scale improved by 0.39 point in the alemtuzumab group and worsened by 0.38 point in the interferon beta-1a group (P<0.001). In the alemtuzumab group, the lesion burden (as seen on T(2)-weighted magnetic resonance imaging) was reduced, as compared with that in the interferon beta-1a group (P=0.005). From month 12 to month 36, brain volume (as seen on T(1)-weighted magnetic resonance imaging) increased in the alemtuzumab group but decreased in the interferon beta-1a group (P=0.02). Adverse events in the alemtuzumab group, as compared with the interferon beta-1a group, included autoimmunity (thyroid disorders [23% vs. 3%] and immune thrombocytopenic purpura [3% vs. 1%]) and infections (66% vs. 47%). There were no significant differences in outcomes between the 12-mg dose and the 24-mg dose of alemtuzumab. CONCLUSIONS: In patients with early, relapsing-remitting multiple sclerosis, alemtuzumab was more effective than interferon beta-1a but was associated with autoimmunity, most seriously manifesting as immune thrombocytopenic purpura. The study was not powered to identify uncommon adverse events. (ClinicalTrials.gov number, NCT00050778.)

Alemtuzumab induction in non-hepatitis C positive liver transplant recipients.

Limited data exist for the use of alemtuzumab (AL) induction in liver transplantation (LT) recipients. We compared the outcomes of hepatitis C virus-negative LT recipients who received AL induction followed by tacrolimus and mycophenolate mofetil without steroids to cohort who received no AL induction, tacrolimus, and a steroid taper. Fifty-five AL-induced recipients were compared to 85 non-AL-induced recipients with similar characteristics. Two-year patient survival (80% versus 88.2%, P = 0.0665) and graft survival (76.4% versus 82.4%, P = 0.1792) were not significantly different between the AL and non-AL groups, respectively. Other outcomes, including acute rejection (20% versus 30.3%), renal dysfunction (creatinine levels: 1.3 ± 0.3 versus 1.4 ± 0.6 mg/dL), and immunosuppressant monotherapy (29.1% versus 44.3%), were not significantly different between the AL and non-AL groups, respectively (P > 0.05). The number of rejection episodes (12 versus 42, P = 0.02) and the number of patients with new-onset hypertension (3 versus 15, P = 0.03) were lower in the AL group, although the incidence of all posttransplant infections was higher with AL (63.6% versus 44.3%, P = 0.03), primarily because of an increase in viral infections. In conclusion, a steroid-free AL induction regimen was associated with less hypertension and rejection but with more infectious complications; thus, the overall benefit of AL induction in LT recipients is called into question.

Alemtuzumab: what is the secret to safe therapy?

Over the past decade, the use of the monoclonal antibody alemtuzumab in chronic lymphocytic leukemia has expanded from administration as a single-agent therapy, into use in combination with fludarabine or rituximab, and further to use as a consolidation agent with the goal of eradicating minimal residual disease. Numerous clinical studies have shown that alemtuzumab is effective as first-line treatment and in patients who have relapsed disease or who are refractory to fludarabine. Despite improvements in response rates and survival compared with combination chemotherapy, there remains some hesitation to incorporate alemtuzumab into management because of known toxicities. Adverse events in patients treated with standard-dose, single-agent alemtuzumab occur at generally predictable time points during treatment and can be managed effectively; this outcome is less established when alemtuzumab is incorporated into combination regimens. Variability in alemtuzumab dosing, route of administration, and duration of therapy has led to inconsistent and sometimes adverse safety consequences. This article presents an overview of clinical studies with alemtuzumab as a single agent, in combination, or in consolidation, with discussion of toxicity and suggestions for ensuring that the efficacious outcomes following alemtuzumab therapy are not outweighed by safety concerns.

Some observations on prope tolerance.

PURPOSE OF REVIEW: To outline the rationale of powerful depleting induction therapy with alemtuzumab and minimal maintenance immunosuppression after organ transplantation. RECENT FINDINGS: The original observations in principle have been confirmed by many independent centres. SUMMARY: Follow-up of the 'prope tolerance' protocol has confirmed a low incidence of rejection, infection and post transplant lymphoproliferative disorder (PTLD). Especially, encouraging results were obtained in African-Americans. There were few side effects and the regimen was well tolerated by patients. Treg cells were observed in the circulation, which could be an important factor in the mechanisms of graft acceptance using a prope tolerance regimen. There was a considerable reduction in the costs of the transplantation procedure. It is suggested that this minimalisation of maintenance immunosuppression is the best therapy currently available that we can offer to our patients.

[Proteins in haematology]. / Proteine in der Hämatologie.

The introduction of monoclonal antibodies has been a milestone in the treatment of hematologic neoplasms. The CD20 antibody rituximab has been a trailblazer and represents meanwhile a fixed combination partner of different first- and second-line chemotherapies in CD20-positive B-cell-non-Hodgkin's lymphoma (NHL). Rituximab maintenance is established in follicular lymphoma. The drug is also used for the treatment of non-malignant hematologic diseases (i.e. immunthrombocytopenia). Rituximab was followed by the CD52 antibody alemtuzumab and recently by the CD20 antibody ofatumumab for the therapy of CLL and the radioimmunconjugate ibritumomab-tiuxetan indicated for the treatment of refractory or relapsed CD20-positive follicular lymphoma or as consolidation after induction chemotherapy. In the near future, approval of several new antibodies is expected. For the treatment of refractory or relapsed Hodgkin's lymphoma and relapsed systemic anaplastic large cell lymphoma, the CD30 antibody brentuximab vedotin has been shown to be a highly active new treatment option.

Alemtuzumab is safe and effective as immunosuppressive treatment for aplastic anaemia and single-lineage marrow failure: a pilot study and a survey from the EBMT WPSAA.

An alemtuzumab-based experimental immunosuppressive treatment (IST) regimen was investigated in 35 patients with severe aplastic anaemia (SAA), pure red cell (PRCA) or pure white cell aplasia (PWCA). Alemtuzumab total dose was 73-103 mg s.c., followed by cyclosporine. No serious toxicity due to the regimen was observed. Adverse events were clinically irrelevant; infectious events were rare. The total response rate was 58%, 84% and 100% in SAA, PRCA and PWCA, respectively, with corresponding 6 months cumulative response probabilities of 84%, 84% and 100%. Subcutaneous alemtuzumab is a feasible and sufficiently safe IST regimen for patients suffering from immune-mediated marrow failures.

B-cell reconstitution and BAFF after alemtuzumab (Campath-1H) treatment of multiple sclerosis.

INTRODUCTION: Treatment with alemtuzumab is highly effective in relapsing-remitting multiple sclerosis; however, 30% of patients develop autoimmunity. Alemtuzumab (previously called Campath 1-H) induces a prolonged T-cell lymphopenia with memory cells dominating the reconstituting T-cell pool for at least 3 months. RESULTS: Here we show that B-cell recovery is rapid, returning to baseline by 3 months and rising to 165% of baseline by 12 months after treatment. Immature transitional 1 B cells are the predominant cell type 1 month after treatment. This coincides with a surge in serum B-cell activating factor (BAFF), which remains elevated by 33% for at least 12 months after alemtuzumab. BAFF is critical for transition to the mature naive B-cell phenotype, which dominates from 3 months after alemtuzumab. Differentiation to memory B cells is slow so there are radical and prolonged alterations to the B-cell pool after alemtuzumab.

Clinical outcome of pretreated B-cell chronic lymphocytic leukemia following alemtuzumab therapy: a retrospective study on various cytogenetic risk categories.

BACKGROUND: Patients with B-cell chronic lymphocytic leukemia (CLL) with 17p deletion respond poorly to chemotherapy. This retrospective study evaluated the benefit of alemtuzumab monotherapy in unselected patients with advanced CLL in the various cytogenetic subgroups. PATIENTS AND METHODS: Data were collected from 105 consecutive, pretreated, cytogenetically defined patients who had received alemtuzumab. Response, progression-free survival (PFS), and overall survival (OS) were assessed. RESULTS: The hierarchic incidence of cytogenetic abnormalities was: 13q deletion (as sole abnormality), 18%; trisomy 12, 13%; 11q deletion, 19%; 17p deletion, 33%; and none of these, 16%. Overall response rate (ORR) was 43% in the total cohort and 49% in the subgroup of 17p-deleted patients (n = 35). From the start of alemtuzumab monotherapy, median PFS in the total cohort and in the subgroup of 17p-deleted patients was 7.0 and 7.1 months, respectively. Median OS in the total cohort and in 17p-deleted patients was 32.8 and 19.1 months, respectively. The poor-risk group of patients with CLL (i.e. fludarabine resistant, 17p deletion; n = 20) showed encouraging ORR, PFS, and OS (35%, 7.0 and 19.2 months, respectively). CONCLUSIONS: Alemtuzumab was effective in treating patients with CLL across the cytogenetic categories evaluated, but there were differences. In patients with CLL with 17p deletion quite favorable ORR, PFS, and OS were achieved.

EBV-positive immunodeficiency lymphoma after alemtuzumab-CHOP therapy for peripheral T-cell lymphoma.

Chemotherapy with alemtuzumab and the combination of cyclophosphamide, adriamycin, oncovin, and prednisone (CHOP) has become experimental trial therapy for aggressive T-cell lymphoma. Several multicenter phase 3 trials will incorporate this scheme. As part of an ongoing phase 2 trial in which we recently treated 20 patients with 8 cycles of CHOP every 2 weeks with 3 additional doses of 30 mg alemtuzumab per cycle, we observed the development of Epstein-Barr virus (EBV)-positive lymphoproliferative disease, after completion of the immunochemotherapy in 3 patients with peripheral T-cell lymphoma. Because the occurrence of EBV-positive lymphoproliferative disease is rare after alemtuzumab monotherapy, such as is given for chronic lymphocytic leukemia, we think that early reporting of this potential side effect is warranted. It may be caused by intrinsic T-cell defects in patients with T-cell lymphoma, or by the combination of alemtuzumab with CHOP chemotherapy.

Isolated left-sided pulmonary edema caused by alemtuzumab (Campath) during kidney transplantation.

Alemtuzumab is a novel anti-CD-52 monoclonal antibody for immunosuppression. Although cost effective and efficacious, alemtuzumab is not without risk. Interestingly, intraoperative complications caused by alemtuzumab have rarely been reported. We describe a case of intraoperative pulmonary edema following administration of alemtuzumab. A 22-year-old man underwent kidney transplantation and received alemtuzumab intraoperatively. To provide better surgical exposure for transplantation, the operation table was tilted to the right. At the end of 3.5-h uneventful procedure, a sudden oxygen desaturation was noted after the bed was flattened. The postoperative chest X-ray showed opacification of the entire left lung field. After 4 days of bi-level positive airway pressure treatment, the lung field was cleared. This case is unique in that pulmonary edema developed during surgery after administration of alemtuzumab, and that the edema developed only in the nondependent lung. Transplant anesthesiologists should be aware of the risk of this complication with these novel anti-CD-52 monoclonal antibodies.

The number of circulating recent thymic emigrants is severely reduced 1 year after a single dose of alemtuzumab in renal transplant recipients.

To better understand the kinetics of the delayed reconstitution of peripheral CD4+ T-cells after depletion with a single administration of alemtuzumab (AL) for renal transplantation, we evaluated in these patients the percentage and absolute number of recent thymic emigrants (RTEs) CD4+ T cells, together with naive and memory subsets, defined by the analysis of CD31, CD45RA and CCR7 expression, and compared with patients treated with a nondepleting protocol based on basiliximab, and with healthy controls. In AL-treated patients, the number of circulating CD4+ T cells was greatly reduced 1 year after the infusion (P < 0.01), but the proportions of central memory, effector memory and terminally differentiated effector memory subsets among CD4+ cells were significantly increased. On the contrary, the proportion and the absolute number of naïve CD4+ T cells, although progressively increasing with time, were severely reduced. In particular, the absolute number of RTEs had only very slight increase with time (P = 0.049) and was dramatically low 1 year after the therapy (P < 0.01 vs. healthy controls; P < 0.05 vs. basiliximab-treated transplant recipients). These data suggest that a prolonged defective thymic output after AL therapy in renal transplant recipients is one of the main causes of the persistent CD4+ T-cell lymphopenia observed in these patients.

Effect of Alemtuzumab (CAMPATH 1-H) in patients with inclusion-body myositis.

Sporadic inclusion-body myositis (sIBM) is the most common disabling, adult-onset, inflammatory myopathy histologically characterized by intense inflammation and vacuolar degeneration. In spite of T cell-mediated cytotoxicity and persistent, clonally expanded and antigen-driven endomysial T cells, the disease is resistant to immunotherapies. Alemtuzumab is a humanized monoclonal antibody that causes an immediate depletion or severe reduction of peripheral blood lymphocytes, lasting at least 6 months. We designed a proof-of-principle study to examine if one series of Alemtuzumab infusions in sIBM patients depletes not only peripheral blood lymphocytes but also endomysial T cells and alters the natural course of the disease. Thirteen sIBM patients with established 12-month natural history data received 0.3 mg/kg/day Alemtuzumab for 4 days. The study was powered to capture > or =10% increase strength 6 months after treatment. The primary end-point was disease stabilization compared to natural history, assessed by bi-monthly Quantitative Muscle Strength Testing and Medical Research Council strength measurements. Lymphocytes and T cell subsets were monitored concurrently in the blood and the repeated muscle biopsies. Alterations in the mRNA expression of inflammatory, stressor and degeneration-associated molecules were examined in the repeated biopsies. During a 12-month observation period, the patients' total strength had declined by a mean of 14.9% based on Quantitative Muscle Strength Testing. Six months after therapy, the overall decline was only 1.9% (P < 0.002), corresponding to a 13% differential gain. Among those patients, four improved by a mean of 10% and six reported improved performance of daily activities. The benefit was more evident by the Medical Research Council scales, which demonstrated a decline in the total scores by 13.8% during the observation period but an improvement by 11.4% (P < 0.001) after 6 months, reaching the level of strength recorded 12 months earlier. Depletion of peripheral blood lymphocytes, including the naive and memory CD8+ cells, was noted 2 weeks after treatment and persisted up to 6 months. The effector CD45RA(+)CD62L(-) cells, however, started to increase 2 months after therapy and peaked by the 4th month. Repeated muscle biopsies showed reduction of CD3 lymphocytes by a mean of 50% (P < 0.008), most prominent in the improved patients, and reduced mRNA expression of stressor molecules Fas, Mip-1a and alphaB-crystallin; the mRNA of desmin, a regeneration-associated molecule, increased. This proof-of-principle study provides insights into the pathogenesis of inclusion-body myositis and concludes that in sIBM one series of Alemtuzumab infusions can slow down disease progression up to 6 months, improve the strength of some patients, and reduce endomysial inflammation and stressor molecules. These encouraging results, the first in sIBM, warrant a future study with repeated infusions