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.)

BACKGROUND

The anti-CD52 monoclonal antibody alemtuzumab reduces disease activity in previously untreated patients with relapsing-remitting multiple sclerosis. We aimed to assess efficacy and safety of alemtuzumab compared with interferon beta 1a in patients who have relapsed despite first-line treatment.

METHODS

In our 2 year, rater-masked, randomised controlled phase 3 trial, we enrolled adults aged 18-55 years with relapsing-remitting multiple sclerosis and at least one relapse on interferon beta or glatiramer. Eligible participants were randomly allocated in a 1:2:2 ratio by an interactive voice response system, stratified by site, to receive subcutaneous interferon beta 1a 44 μg, intravenous alemtuzumab 12 mg per day, or intravenous alemtuzumab 24 mg per day. Interferon beta 1a was given three-times per week and alemtuzumab was given once per day for 5 days at baseline and for 3 days at 12 months. The 24 mg per day group was discontinued to aid recruitment, but data are included for safety assessments. Coprimary endpoints were relapse rate and time to 6 month sustained accumulation of disability, comparing alemtuzumab 12 mg and interferon beta 1a in all patients who received at least one dose of study drug. This study is registered with ClinicalTrials.gov, number NCT00548405.

RESULTS

202 (87%) of 231 patients randomly allocated interferon beta 1a and 426 (98%) of 436 patients randomly allocated alemtuzumab 12 mg were included in the primary analyses. 104 (51%) patients in the interferon beta 1a group relapsed (201 events) compared with 147 (35%) patients in the alemtuzumab group (236 events; rate ratio 0·51 [95% CI 0·39-0·65]; p<0·0001), corresponding to a 49·4% improvement with alemtuzumab. 94 (47%) patients in the interferon beta 1a group were relapse-free at 2 years compared with 278 (65%) patients in the alemtuzumab group (p<0·0001). 40 (20%) patients in the interferon beta 1a group had sustained accumulation of disability compared with 54 (13%) in the alemtuzumab group (hazard ratio 0·58 [95% CI 0·38-0·87]; p=0·008), corresponding to a 42% improvement in the alemtuzumab group. For 435 patients allocated alemtuzumab 12 mg, 393 (90%) had infusion-associated reactions, 334 (77%) had infections (compared with 134 [66%] of 202 patients in the interferon beta 1a group) that were mostly mild-moderate with none fatal, 69 (16%) had thyroid disorders, and three (1%) had immune thrombocytopenia.

CONCLUSIONS

For patients with first-line treatment-refractory relapsing-remitting multiple sclerosis, alemtuzumab could be used to reduce relapse rates and sustained accumulation of disability. Suitable risk management strategies allow for early identification of alemtuzumab's main adverse effect of secondary autoimmunity.

BACKGROUND

Genzyme (Sanofi) and Bayer Schering Pharma.

BACKGROUND

The anti-CD52 monoclonal antibody alemtuzumab reduced disease activity in a phase 2 trial of previously untreated patients with relapsing-remitting multiple sclerosis. We aimed to assess efficacy and safety of first-line alemtuzumab compared with interferon beta 1a in a phase 3 trial.

METHODS

In our 2 year, rater-masked, randomised controlled phase 3 trial, we enrolled adults aged 18-50 years with previously untreated relapsing-remitting multiple sclerosis. Eligible participants were randomly allocated in a 2:1 ratio by an interactive voice response system, stratified by site, to receive intravenous alemtuzumab 12 mg per day or subcutaneous interferon beta 1a 44 μg. Interferon beta 1a was given three-times per week and alemtuzumab was given once per day for 5 days at baseline and once per day for 3 days at 12 months. Coprimary endpoints were relapse rate and time to 6 month sustained accumulation of disability in all patients who received at least one dose of study drug. This study is registered with ClinicalTrials.gov, number NCT00530348.

RESULTS

187 (96%) of 195 patients randomly allocated interferon beta 1a and 376 (97%) of 386 patients randomly allocated alemtuzumab were included in the primary analyses. 75 (40%) patients in the interferon beta 1a group relapsed (122 events) compared with 82 (22%) patients in the alemtuzumab group (119 events; rate ratio 0·45 [95% CI 0·32-0·63]; p<0.0001), corresponding to a 54·9% improvement with alemtuzumab. Based on Kaplan-Meier estimates, 59% of patients in the interferon beta 1a group were relapse-free at 2 years compared with 78% of patients in the alemtuzumab group (p<0·0001). 20 (11%) of patients in the interferon beta 1a group had sustained accumulation of disability compared with 30 (8%) in the alemtuzumab group (hazard ratio 0·70 [95% CI 0·40-1·23]; p=0·22). 338 (90%) of patients in the alemtuzumab group had infusion-associated reactions; 12 (3%) of which were regarded as serious. Infections, predominantly of mild or moderate severity, occurred in 253 (67%) patients treated with alemtuzumab versus 85 (45%) patients treated with interferon beta 1a. 62 (16%) patients treated with alemtuzumab had herpes infections (predominantly cutaneous) compared with three (2%) patients treated with interferon beta 1a. By 24 months, 68 (18%) patients in the alemtuzumab group had thyroid-associated adverse events compared with 12 (6%) in the interferon beta 1a group, and three (1%) had immune thrombocytopenia compared with none in the interferon beta 1a group. Two patients in the alemtuzumab group developed thyroid papillary carcinoma.

CONCLUSIONS

Alemtuzumab's consistent safety profile and benefit in terms of reductions of relapse support its use for patients with previously untreated relapsing-remitting multiple sclerosis; however, benefit in terms of disability endpoints noted in previous trials was not observed here.

BACKGROUND

Genzyme (Sanofi) and Bayer Schering Pharma.

Antibody-dependent cell-mediated cytotoxicity, a key effector function for the clinical efficacy of monoclonal antibodies, is mediated primarily through a set of closely related Fcgamma receptors with both activating and inhibitory activities. By using computational design algorithms and high-throughput screening, we have engineered a series of Fc variants with optimized Fcgamma receptor affinity and specificity. The designed variants display >2 orders of magnitude enhancement of in vitro effector function, enable efficacy against cells expressing low levels of target antigen, and result in increased cytotoxicity in an in vivo preclinical model. Our engineered Fc regions offer a means for improving the next generation of therapeutic antibodies and have the potential to broaden the diversity of antigens that can be targeted for antibody-based tumor therapy.

This study investigated the efficacy, safety, and clinical benefit of alemtuzumab (Campath-1H) for patients with relapsed or refractory B-cell chronic lymphocytic leukemia exposed to alkylating agents and having failed fludarabine therapy. Ninety-three patients received alemtuzumab in 21 centers worldwide, with the aim to obtain an overall response rate of at least 20%. Dosage was increased gradually (target 30 mg, 3 times weekly, for a maximum of 12 weeks). Infection prophylaxis was mandatory, beginning on day 8, and continuing for a minimum of 2 months after treatment. Responses were assessed at weeks 4, 8, and 12, and patients were followed for 34 months. Overall objective response in the intent-to-treat population (n = 93) was 33% (CR 2%, PR 31%). Median time to response was 1.5 months (range, 0.4-3.7 months). Median time to progression was 4.7 months overall, 9.5 months for responders. At data cut-off, 27 patients (29%) were alive; overall median survival was 16 months (95% CI: 11.8-21.9) and 32 months for responders. Nineteen responders survived more than 21 months. Clinical benefit was observed both in responders and in patients with stable disease. The most common adverse events were related to infusion, generally grade 1 or 2 in severity, occurring mainly in the first week. Grade 3 or 4 infections were reported in 25 patients (26.9%). However, only 3 (9.7%) of 31 patients who responded to alemtuzumab treatment developed grade 3 or 4 infections on the study. Alemtuzumab induced significant responses in these patients with clinical benefit in the majority and with acceptable toxicity in a high-risk group.

T-cell depletion facilitates reduced immunosuppression following organ transplantation and has been suggested to be pro-tolerant. However, the characteristics of post-depletional T cells have not been evaluated as they relate to tolerance induction. We therefore studied patients undergoing profound T-cell depletion with alemtuzumab or rabbit anti-thymocyte globulin following renal transplantation, evaluating the phenotype and functional characteristics of their residual cells. Naive T cells and T cells with potential regulatory function (CD4+CD25+) were not prevalent following aggressive depletion. Rather, post-depletion T cells were of a single phenotype (CD3+CD4+CD45RA-CD62L-CCR7-) consistent with depletion-resistant effector memory T cells that expanded in the first month and were uniquely prevalent at the time of rejection. These cells were resistant to steroids, deoxyspergualin or sirolimus in vitro, but were calcineurin-inhibitor sensitive. These data demonstrate that therapeutic depletion begets a limited population of functional memory-like T cells that are easily suppressed with certain immunosuppressants, but cannot be considered uniquely pro-tolerant.

From 1991-2002, we treated 58 patients with multiple sclerosis (MS) using the humanised monoclonal antibody, Campath-1H, which causes prolonged T lymphocyte depletion. Clinical and surrogate markers of inflammation were suppressed. In both the relapsing-remitting (RR) and secondary progressive (SP) stages of the illness, Campath-1H reduced the annual relapse rate (from 2.2 to 0.19 and from 0.7 to 0.001 respectively; both p < 0.001). Remarkably, MRI scans of patients with SP disease, treated with Campath-1H 7 years previously, showed no new lesion formation. However, despite these effects on inflammation, disability was differently affected depending on the phase of the disease. Patients with SPMS showed sustained accumulation of disability due to uncontrolled progression marked by unrelenting cerebral atrophy, attributable to ongoing axonal loss. The rate of cerebral atrophy was greatest in patients with established cerebral atrophy and highest inflammatory lesion burden before treatment (2.3 versus 0.7 ml/year; p = 0.04). In contrast, patients with RR disease showed an impressive reduction in disability at 6 months after Campath-1H (by a mean of 1.2 EDSS points) perhaps owing to a suppression of on-going inflammation in these patients with unusually active disease. In addition, there was a further significant, albeit smaller, mean improvement in disability up to 36 months after treatment. We speculate that this represents the beneficial effects of early rescue of neurons and axons from a toxic inflammatory environment, and that prevention of demyelination will prevent long-term axonal degeneration. These concepts are currently being tested in a controlled trial comparing Campath-1H and IFN-beta in the treatment of drug-naïve patients with early, active RR MS.

OBJECTIVE

We conducted a randomized trial to evaluate the efficacy and safety of intravenous alemtuzumab compared with chlorambucil in first-line treatment of chronic lymphocytic leukemia (CLL).

METHODS

Patients received alemtuzumab (30 mg three times per week, for up to 12 weeks) or chlorambucil (40 mg/m(2) every 28 days, for up to 12 months). The primary end point was progression-free survival (PFS). Secondary end points included overall response rate (ORR), complete response (CR), time to alternative therapy, safety, and overall survival.

RESULTS

We randomly assigned 297 patients, 149 to alemtuzumab and 148 to chlorambucil. Alemtuzumab had superior PFS, with a 42% reduction in risk of progression or death (hazard ratio [HR] = 0.58; P = .0001), and a median time to alternative treatment of 23.3 versus 14.7 months for chlorambucil (HR = 0.54; P = .0001). The ORR was 83% with alemtuzumab (24% CR) versus 55% with chlorambucil (2% CR); differences in ORR and CR were highly statistically significant (P < .0001). Elimination of minimal residual disease occurred in 11 of 36 complete responders to alemtuzumab versus none to chlorambucil. Adverse events profiles were similar, except for more infusion-related and cytomegalovirus (CMV) events with alemtuzumab and more nausea and vomiting with chlorambucil. CMV events had no apparent impact on efficacy.

CONCLUSIONS

As first-line treatment for patients with CLL, alemtuzumab demonstrated significantly improved PFS, time to alternative treatment, ORR and CR, and minimal residual disease-negative remissions compared with chlorambucil, with predictable and manageable toxicity.

Adoptive immunotherapy using autologous T cells endowed with chimeric antigen receptors (CAR) has emerged as a powerful means of treating cancer. However, a limitation of this approach is that autologous CAR T cells must be generated on a custom-made basis. Here we show that electroporation of transcription activator-like effector nuclease (TALEN) mRNA allows highly efficient multiplex gene editing in primary human T cells. We use this TALEN-mediated editing approach to develop a process for the large-scale manufacturing of T cells deficient in expression of both their αβ T-cell receptor (TCR) and CD52, a protein targeted by alemtuzumab, a chemotherapeutic agent. Functionally, T cells manufactured with this process do not mediate graft-versus-host reactions and are rendered resistant to destruction by alemtuzumab. These characteristics enable the administration of alemtuzumab concurrently or prior to engineered T cells, supporting their engraftment. Furthermore, endowing the TALEN-engineered cells with a CD19 CAR led to efficient destruction of CD19(+) tumor targets even in the presence of the chemotherapeutic agent. These results demonstrate the applicability of TALEN-mediated genome editing to a scalable process, which enables the manufacturing of third-party CAR T-cell immunotherapies against arbitrary targets. As such, CAR T-cell immunotherapies can therefore be used in an "off-the-shelf" manner akin to other biologic immunopharmaceuticals

BACKGROUND

Myeloablative allogeneic hematopoietic stem-cell transplantation is curative in children with sickle cell disease, but in adults the procedure is unduly toxic. Graft rejection and graft-versus-host disease (GVHD) are additional barriers to its success. We performed nonmyeloablative stem-cell transplantation in adults with sickle cell disease.

METHODS

Ten adults (age range, 16 to 45 years) with severe sickle cell disease underwent nonmyeloablative transplantation with CD34+ peripheral-blood stem cells, mobilized by granulocyte colony-stimulating factor (G-CSF), which were obtained from HLA-matched siblings. The patients received 300 cGy of total-body irradiation plus alemtuzumab before transplantation, and sirolimus was administered afterward.

RESULTS

All 10 patients were alive at a median follow-up of 30 months after transplantation (range, 15 to 54). Nine patients had long-term, stable donor lymphohematopoietic engraftment at levels that sufficed to reverse the sickle cell disease phenotype. Mean (+/-SE) donor-recipient chimerism for T cells (CD3+) and myeloid cells (CD14+15+) was 53.3+/-8.6% and 83.3+/-10.3%, respectively, in the nine patients whose grafts were successful. Hemoglobin values before transplantation and at the last follow-up assessment were 9.0+/-0.3 and 12.6+/-0.5 g per deciliter, respectively. Serious adverse events included the narcotic-withdrawal syndrome and sirolimus-associated pneumonitis and arthralgia. Neither acute nor chronic GVHD developed in any patient.

CONCLUSIONS

A protocol for nonmyeloablative allogeneic hematopoietic stem-cell transplantation that includes total-body irradiation and treatment with alemtuzumab and sirolimus can achieve stable, mixed donor-recipient chimerism and reverse the sickle cell phenotype. (ClinicalTrials.gov number, NCT00061568.)

The immunotherapy of cancer has made significant strides in the past few years due to improved understanding of the underlying principles of tumor biology and immunology. These principles have been critical in the development of immunotherapy in the laboratory and in the implementation of immunotherapy in the clinic. This improved understanding of immunotherapy, enhanced by increased insights into the mechanism of tumor immune response and its evasion by tumors, now permits manipulation of this interaction and elucidates the therapeutic role of immunity in cancer. Also important, this improved understanding of immunotherapy and the mechanisms underlying immunity in cancer has fueled an expanding array of new therapeutic agents for a variety of cancers. Pegylated interferon-α2b as an adjuvant therapy and ipilimumab as therapy for advanced disease, both of which were approved by the United States Food and Drug Administration for melanoma in March 2011, are 2 prime examples of how an increased understanding of the principles of tumor biology and immunology have been translated successfully from the laboratory to the clinical setting. Principles that guide the development and application of immunotherapy include antibodies, cytokines, vaccines, and cellular therapies. The identification and further elucidation of the role of immunotherapy in different tumor types, and the development of strategies for combining immunotherapy with cytotoxic and molecularly targeted agents for future multimodal therapy for cancer will enable even greater progress and ultimately lead to improved outcomes for patients receiving cancer immunotherapy.

The elective treatment of patients with multiple sclerosis, using a humanized anti-leukocyte (CD52) monoclonal antibody (Campath-1H), has illuminated mechanisms that underlie the clinical course of the disease. Twenty-seven patients were studied clinically and by magnetic resonance imaging (MRI) before and for 18 months after a single pulse of Campath-1H. The first dose of monoclonal antibody was associated with a transient rehearsal of previous symptoms caused by the release of mediators that impede conduction at previously demyelinated sites; this effect remained despite selective blockade of tumor necrosis factor-alpha. Disease activity persisted for several weeks after treatment but thereafter radiological markers of cerebral inflammation were suppressed for at least 18 months during which there were no new symptoms or signs. However, about half the patients experienced progressive disability and increasing brain atrophy, attributable on the basis of MRI spectroscopy to axonal degeneration, which correlated with the extent of cerebral inflammation in the pretreatment phase. These data support the formulation that inflammation and demyelination are responsible for relapses of multiple sclerosis; that inflammatory mediators, but not tumor necrosis factor-alpha, cause symptomatic reactivation of previously demyelinated lesions; and that axonal degeneration, conditioned by prior inflammation but proceeding despite its suppression, contributes to the progressive phase of disability. These results provide evidence supporting the emerging view that treatment in multiple sclerosis must be given early in the course, before the consequences of inflammation are irretrievably established.

BACKGROUND

Profound T-cell depletion before allotransplantation with gradual posttransplant T-cell repopulation induces a state of donor-specific immune hyporesponsiveness or tolerance in some animal models. Alemtuzumab (Campath-1H, Millennium Pharmaceuticals, Cambridge, MA) is a humanized CD52-specific monoclonal antibody that produces profound T-cell depletion in humans and reduces the need for maintenance immunosuppression after renal transplantation. We therefore performed a study to determine if pretransplant T-cell depletion with alemtuzumab would induce tolerance in human renal allografts and to evaluate the nature of the alloimmune response in the setting of T-cell depletion.

METHODS

Seven nonsensitized recipients of living-donor kidneys were treated perioperatively with alemtuzumab and followed postoperatively without maintenance immunosuppression. Patients were evaluated clinically by peripheral flow cytometry, protocol biopsies evaluated immunohistochemically, and real-time polymerase chain reaction-based transcriptional analysis.

RESULTS

Lymphocyte depletion was profound in the periphery and secondary lymphoid tissues. All patients developed reversible rejection episodes within the first month that were characterized by predominantly monocytic (not lymphocytic) infiltrates with only rare T cells in the peripheral blood or allograft. These episodes were responsive to treatment with steroids or sirolimus or both. After therapy, patients remained rejection-free on reduced immunosuppression, generally monotherapy sirolimus, despite the recovery of lymphocytes to normal levels.

CONCLUSIONS

T-cell depletion alone does not induce tolerance in humans. These data underscore a prominent role for early responding monocytes in human allograft rejection.

Phase II clinical trials revealed that the lymphocyte-depleting humanized monoclonal antibody alemtuzumab (Campath-1H) is highly effective in the treatment of early relapsing-remitting multiple sclerosis. However, 30% of patients develop autoimmunity months to years after pulsed exposure to alemtuzumab, usually targeting the thyroid gland and, more rarely, blood components. In this study, we show that autoimmunity arose in those patients with greater T cell apoptosis and cell cycling in response to alemtuzumab-induced lymphocyte depletion, a phenomenon that is driven by higher levels of IL-21. Before treatment, patients who went on to develop secondary autoimmunity had more than 2-fold greater levels of serum IL-21 than the nonautoimmune group. We suggest that serum IL-21 may, therefore, serve as a biomarker for the risk of developing autoimmunity months to years after alemtuzumab treatment. This has implications for counseling those patients with multiple sclerosis who are considering lymphocyte-depleting therapy with alemtuzumab. Finally, we demonstrate through genotyping that IL-21 expression is genetically predetermined. We propose that, by driving cycles of T cell expansion and apoptosis to excess, IL-21 increases the stochastic opportunities for T cells to encounter self antigen and, hence, for autoimmunity.

The skin of an adult human contains about 20 billion memory T cells. Epithelial barrier tissues are infiltrated by a combination of resident and recirculating T cells in mice, but the relative proportions and functional activities of resident versus recirculating T cells have not been evaluated in human skin. We discriminated resident from recirculating T cells in human-engrafted mice and lymphoma patients using alemtuzumab, a medication that depletes recirculating T cells from skin, and then analyzed these T cell populations in healthy human skin. All nonrecirculating resident memory T cells (TRM) expressed CD69, but most were CD4(+), CD103(-), and located in the dermis, in contrast to studies in mice. Both CD4(+) and CD8(+) CD103(+) TRM were enriched in the epidermis, had potent effector functions, and had a limited proliferative capacity compared to CD103(-) TRM. TRM of both types had more potent effector functions than recirculating T cells. We observed two distinct populations of recirculating T cells, CCR7(+)/L-selectin(+) central memory T cells (TCM) and CCR7(+)/L-selectin(-) T cells, which we term migratory memory T cells (TMM). Circulating skin-tropic TMM were intermediate in cytokine production between TCM and effector memory T cells. In patients with cutaneous T cell lymphoma, malignant TCM and TMM induced distinct inflammatory skin lesions, and TMM were depleted more slowly from skin after alemtuzumab, suggesting that TMM may recirculate more slowly. In summary, human skin is protected by four functionally distinct populations of T cells, two resident and two recirculating, with differing territories of migration and distinct functional activities.

We report the outcome of reduced-intensity allogeneic progenitor cell transplantation (alloPCT) for 188 patients with lymphoma from the Working Party Lymphoma of the European Group for Blood and Bone Marrow Transplantation (EBMT). The median age of the patients was 40 years, the median number of prior treatment courses was 3, and 48% of patients had undergone a prior autologous transplantation. Eighty-four percent of the patients received conditioning with fludarabine-based regimens and 10% with the BEAM (BCNU, etoposide, cytosine arabinoside, melphalan) protocol. Full donor chimerism was confirmed in 71% of 100 patients assessed. Acute graft-versus-host disease (GVHD) developed in 37% of patients and chronic GVHD in 17%. A disease response to donor leukocyte infusion (DLI) was seen in 10 of 14 patients. With a median follow-up of 283 days, the overall survival rates at 1 and 2 years were 62% and 50%, respectively. The 100-day and 1-year transplantation-related mortality (TRM) rates were 12.8% and 25.5%, respectively, and were significantly worse for older patients. The probability of disease progression at 1 year for patients with chemoresistant and chemosensitive disease were 75% and 25%, respectively (P =.001). The progression-free survival at 1 year was 46% and was significantly better for those with chemosensitive disease, Hodgkin disease (HD), and low-grade non-Hodgkin lymphoma (NHL). Patients with high-grade NHL, mantle cell lymphoma, or chemoresistant disease had a poor outcome. Reduced-intensity progenitor cell transplantation is associated with a reduced TRM and may control advanced HD and low-grade NHL. A longer period of follow-up is required to determine the benefit of DLI and the graft-versus-lymphoma effect.

Alemtuzumab is a humanized monoclonal antibody against CD52, an antigen found on the surface of normal and malignant lymphocytes. It is approved for the treatment of B-cell chronic lymphocytic leukaemia and is undergoing Phase III clinical trials for the treatment of multiple sclerosis. The exact mechanism by which alemtuzumab mediates its biological effects in vivo is not clearly defined and mechanism of action studies have been hampered by the lack of cross-reactivity between human and mouse CD52. To address this issue, a transgenic mouse expressing human CD52 (hCD52) was created. Transgenic mice did not display any phenotypic abnormalities and were able to mount normal immune responses. The tissue distribution of hCD52 and the level of expression by various immune cell populations were comparable to those seen in humans. Treatment with alemtuzumab replicated the transient increase in serum cytokines and depletion of peripheral blood lymphocytes observed in humans. Lymphocyte depletion was not as profound in lymphoid organs, providing a possible explanation for the relatively low incidence of infection in alemtuzumab-treated patients. Interestingly, both lymphocyte depletion and cytokine induction by alemtuzumab were largely independent of complement and appeared to be mediated by neutrophils and natural killer cells because removal of these populations with antibodies to Gr-1 or asialo-GM-1, respectively, strongly inhibited the activity of alemtuzumab whereas removal of complement by treatment with cobra venom factor had no impact. The hCD52 transgenic mouse appears to be a useful model and has provided evidence for the previously uncharacterized involvement of neutrophils in the activity of alemtuzumab.

BACKGROUND

Multiple sclerosis results from T-cell-dependent inflammatory demyelination of the central nervous system. Our objective was long-term suppression of inflammation with short-term monoclonal antibody treatment.

METHODS

We depleted 95% of circulating lymphocytes in 27 patients with multiple sclerosis by means of a 5-day pulse of the humanised anti-CD52 monoclonal antibody, Campath-1H. Clinical and haematological consequences of T-cell depletion, and in-vitro responses of patients' peripheral-blood mononuclear cells were analysed serially for 18 months after treatment.

RESULTS

Radiological and clinical markers of disease activity were significantly decreased for at least 18 months after treatment. However, a third of patients developed antibodies against the thyrotropin receptor and carbimazole-responsive autoimmune hyperthyroidism. The depleted peripheral lymphocyte pool was reconstituted with cells that had decreased mitogen-induced proliferation and interferon gamma secretion in vitro.

CONCLUSIONS

Campath-1H causes the immune response to change from the Th1 phenotype, suppressing multiple sclerosis disease activity, but permitting the generation of antibody-mediated thyroid autoimmunity.

Campath-1H, an anti-CD52 monoclonal antibody, was used as induction therapy (40 mg i.v. total dose) in 29 primary human renal transplants, and the patients were maintained on rapamycin monotherapy (levels 8-15 ng/mL) post-transplant. Campath-1H profoundly depletes lymphocytes long-term and more transiently depletes B cells and monocytes. All patients are alive and well at 3-29 months of follow up. One graft was lost because of rejection. There have been no systemic infections and no malignancies. Eight of 29 patients have experienced rejection, which was successfully treated in seven of eight patients. Five of these patients had pathological evidence of a humoral component of their rejection. Seven of the 29 patients were converted to standard triple therapy on account of rejection. Rapamycin was generally well tolerated in that there were no significant wound-healing problems; two lymphoceles required surgical drainage; and most patients were treated with a lipid-lowering agent. Flow crossmatch testing post-transplant revealed evidence of alloantibody in two patients tested with previous combined cellular and humoral rejection. Biopsies have shown no chronic allograft nephropathy to date. In view of the relatively high incidence of early humoral rejection, we plan to modify the immunosuppressive regimen in subsequent pilot studies. This clinical trial provides insight into the use of Campath-1H induction in combination with rapamycin maintenance monotherapy.

The prognosis of fludarabine (F)-refractory chronic lymphocytic leukemia (CLL) is very poor, and underlying mechanisms are only partly understood. To assess the contribution of p53 abnormalities to F-refractory CLL, we studied TP53 mutations in the CLL2H trial (subcutaneous alemtuzumab; n = 99). We found TP53 mutations in 37% of patients. Twelve of 67 (18%) patients without the 17p deletion showed a TP53 mutation and 50% showed evidence of uniparental disomy. A total of 75% of cases with TP53 mutation (without 17p-) showed clonal evolution/expansion. TP53 mutations had no impact on overall survival (P = .48). CLL with the 17p deletion or TP53 mutation showed very low miR-34a expression. To investigate the mechanisms underlying refractory CLL beyond p53, we studied cases without 17p-/TP53 mutation in detail. In several paired samples before and after F-refractory disease, no change in p21/p53 induction was observed after DNA damage. Although TP53 mutations and 17p deletions are found in a high proportion of F-refractory CLL, more than half of the cases cannot be explained by p53 defects (deletion or mutation), and alternative mechanisms need to be investigated. Alemtuzumab is effective irrespective of genetic high-risk subgroups with TP53 mutations. These clinical trials are registered at www.clinicaltrials.gov as #NCT00274976.

Cutaneous T cell lymphoma (CTCL) is a cancer of skin-homing T cells with variants that include leukemic CTCL (L-CTCL), a malignancy of central memory T cells (T(CM)), and mycosis fungoides (MF), a malignancy of skin resident effector memory T cells (T(EM)). We report that low-dose alemtuzumab (αCD52) effectively treated patients with refractory L-CTCL but not MF. Alemtuzumab depleted all T cells in blood and depleted both benign and malignant T(CM) from skin, but a diverse population of skin resident T(EM) remained in skin after therapy. T cell depletion with alemtuzumab required the presence of neutrophils, a cell type frequent in blood but rare in normal skin. These data suggest that T(CM) were depleted because they recirculate between the blood and the skin, whereas skin resident T(EM) were spared because they are sessile and non-recirculating. After alemtuzumab treatment, skin T cells produced lower amounts of interleukin-4 and higher amounts of interferon-γ. Moreover, there was a marked lack of infections in alemtuzumab-treated L-CTCL patients despite the complete absence of T cells in the blood, suggesting that skin resident T(EM) can protect the skin from pathogens even in the absence of T cell recruitment from the circulation. Together, these data suggest that alemtuzumab may treat refractory L-CTCL without severely compromising the immune response to infection by depleting circulating T(CM) but sparing the skin resident T(EM) that provide local immune protection of the skin.

OBJECTIVE

CAMPATH-1H is a human immunoglobulin G1 (IgG1) anti-CD52 monoclonal antibody (MAb) that binds to nearly all B- and T-cell lymphomas and leukemias. We report the results of a multicenter phase II trial that used CAMPATH-1H in previously chemotherapy-treated patients with chronic lymphocytic leukemia (CLL).

METHODS

Twenty-nine patients who had relapsed after an initial response (n = 8) or were refractory (n = 21) to chemotherapy were treated with CAMPATH-1H administered as a 30-mg 2-hour intravenous (IV) infusion thrice weekly for a maximum period of 12 weeks.

RESULTS

Eleven patients (38%) achieved a partial remission (PR) and one (4%) a complete remission (CR) (response rate, 42%; 95% confidence interval [CI], 23% to 61%). Three of eight patients (38%) with a relapse and nine of 21 refractory patients (43%) responded to CAMPATH-1H therapy. CLL cells were rapidly eliminated from blood in 28 of 29 patients (97%). CR in the bone marrow was obtained in 36% and splenomegaly resolved completely in 32%. Lymphadenopathy was normalized in only two patients (7%). The median response duration was 12 months (range, 6 to 25+). World Health Organization (WHO) grade IV neutropenia and thrombocytopenia developed in three (10%) and two patients (7%), respectively. Neutropenia and thrombocytopenia recovered in most responding patients during continued CAMPATH-1H treatment. Lymphopenia (< 0.5 x 10(9)/L) occurred in all patients. Two patients had opportunistic infections and four had bacterial septicemia.

CONCLUSIONS

CAMPATH-1H had significant activity in patients with advanced and chemotherapy-resistant CLL. The most pronounced effects were noted in blood, bone marrow, and spleen. Preferential clearance of blood may allow harvesting of uncontaminated blood stem cells for use in high-dose chemotherapy protocols.

This phase II study determined the efficacy and safety of alemtuzumab, a humanized anti-CD52 monoclonal antibody, delivered subcutaneously as first-line therapy, over a prolonged treatment period of 18 weeks in 41 patients with symptomatic B-cell chronic lymphocytic leukemia (B-CLL). Injections were administered subcutaneously 3 times per week, from week 2 to 3 onward. An overall response rate (OR) of 87% (95% CI, 76%-98%; complete remission [CR], 19%; partial remission [PR], 68%) was achieved in 38 evaluable patients (81% of intent-to-treat population). CLL cells were cleared from blood in 95% patients in a median time of 21 days. CR or nodular PR in the bone marrow was achieved in 66% of the patients and most patients achieved this after 18 weeks of treatment. An 87% OR (29% CR) was achieved in the lymph nodes. The median time to treatment failure has not yet been reached (18+ months; range, 8-44+ months). Transient injection site skin reactions were seen in 90% of patients. Rigor, rash, nausea, dyspnea, and hypotension were rare or absent. Transient grade IV neutropenia developed in 21% of the patients. Infections were rare, but 10% patients developed cytomegalovirus (CMV) reactivation. These patients rapidly responded to intravenous ganciclovir. One patient, allergic to cotrimoxazole prophylaxis, developed Pneumocystis carinii pneumonia. Alemtuzumab is highly effective as first-line treatment in patients with B-CLL. Prolonged treatment is important for maximal bone marrow response. Subcutaneous administration induced very few "first-dose" flulike symptoms and may reduce health care costs in comparison with the intravenous infusions.