Anti-neoplastic biosimilars--the same rules as for cytotoxic generics cannot be applied.

Biopharmaceuticals are complex protein molecule drugs produced by living organisms. Biopharmaceuticals as anti-neoplastic monoclonal antibodies are a major breakthrough in oncology. When the patent of innovator biopharmaceuticals expires, copies will be introduced. These copies are after approval by European Medicines Agency (EMA) within EU called biosimilars and have their own regulatory pathways which differ from the chemical generics approval process. The main reason is that identical copies of chemical molecules via chemical syntheses can be produced but copies of innovator biopharmaceuticals will only be similar. An extensive comparability exercise has to be carried out between the reference product and the biosimilar before approval. However, still there might be differences between the innovator anti-neoplastic monoclonal antibody and the biosimilar anti-neoplastic antibody which cannot be detected until extended clinical studies have been carried out. Moreover, all indications for an anti-neoplastic biosimilar antibody may not have been tested for at the time of approval but extrapolated based on the indications of the reference monoclonal antibody. The limited information on biosimilar anti-neoplastic monoclonal antibodies at approval may still be justified taking into account that the aim is to reduce price. However, the risk-benefit ratio for biosimilar anti-neoplastic monoclonal antibodies should be carefully evaluated, considering that anti-neoplastic monoclonal antibody therapy has a curative intent, price reduction so far within EU of biosimilars is modest and that in the end only part of the total costs for cancer health care is related to biopharmaceuticals.

Presence of clonal T cell populations in chronic B lymphocytic leukemia and smoldering myeloma.

Clonality in the non-neoplastic T cell population was investigated in 21 patients with B cell chronic leukemic (B-CLL) or multiple myeloma (MM) by probing for TCR beta chain gene rearrangements using Southern blot analysis. In three patients with a benign form of B-CLL (stage 0), and in one patient with smoldering MM, evidence was found for predominant T cell clones. As cellular immunity against the malignant cells may be important in leukemia, the results are discussed in view of the potential role of T cell immunity in B-CLL and MM.

Generation of a dendritic cell-based vaccine in chronic lymphocytic leukaemia using CliniMACS platform for large-scale production.

We previously demonstrated that dendritic cells (DC) that have endocytosed apoptotic bodies of autologous leukemic cells (Apo-DC) can boost antileukemic T-cell responses. In this study, we report a description of the production procedure and product specification of the Apo-DC vaccine preparations for clinical use. Enriched populations of CD14+ monocytic precursors and CD19+ leukaemic cells were obtained using CliniMACS technology from a single leukapheresis product. Apoptotic bodies were obtained by irradiating (5 Gy) CD19+ selected B cells. DC were generated ex vivo by culturing monocytes with granulocyte macrophage colony-stimulating factor and interleukin-4. Following coculture with apoptotic bodies, DCs were matured with tumour necrosis factor-alpha. The mean percentage of CD14+ cells in the peripheral blood as well as in the leukapheresis product of the patients (n = 10) was approximately 2% (range, 0.8-3.3). Immunomagnetic selection using the CD14 reagent yielded a CD14+ population that was 91 +/- 2.2% (mean +/- SEM) pure. Immunomagnetic selection of CD19 expressing cells yielded a population that was 100 +/- 0.03% pure. Cell viability immediately after selection was 97% and 98% after 7 days of culture. The Apo-DC cellular vaccine product showed a mature phenotype, with a high rate of endocytosis (84%) of apoptotic leukemic B-cells. In conclusion, despite significant variability in the circulating monocyte frequency of the chronic lymphocytic leukaemia patients, our method permitted the production of a DC vaccine with high reproducibility and conforming with recommended quality standards.

Cancer vaccines for non-small-cell lung cancer.

Lung cancer is globally the second most common form of cancer in both men and women and the single largest cause of cancer-related mortality in the world. It is a disease with poor prognosis and the survival statistics have scarcely improved since historical times. The advent of targeted therapies has caused an incremental increase in survival figures. Nevertheless, significant progress in treatment outcomes need to be achieved before any perceptible improvement in overall survival of lung cancer patients becomes evident. The use of active-specific immunotherapy or cancer vaccines for the treatment of lung cancer is still in its infancy. Nevertheless several cancer vaccines have demonstrated clinical effects and improvements in overall survival in phase II and phase III trials and several more clinical trials are currently ongoing. This review summarizes the recent developments in NSCLC vaccines.

The challenge of biosimilars.

BACKGROUND: The purpose of this report was to review issues associated with the introduction of alternative versions of biosimilars used in the oncology setting. DESIGN: Data were obtained by searches of MEDLINE, PubMed, references from relevant English-language articles, and guidelines from the European Medicines Agency. RESULTS: When biosimilars are approved in EU, they will be considered 'comparable' to the reference product, but this does not ensure therapeutic equivalence. Inherent differences between biosimilars may produce dissimilarities in clinical efficacy, safety, and immunogenicity. Switching biosimilars should be considered a change in clinical management. Regulatory guidelines have been established for some biosimilar categories but, because of the limited clinical experience with biosimilars at approval, pharmacovigilance programs will be important to establish clinical databases. Guidelines also provide a mechanism for the extrapolation of clinical indications (approved indications for which the biosimilar has not been studied). This may be of concern where differences in biological activity can result in adverse outcomes or when safety is paramount (e.g. stem cell mobilization in healthy donors). These issues should be addressed in biosimilar labeling. CONCLUSIONS: Biosimilars should provide cost savings and greater accessibility to biopharmaceuticals. A thorough knowledge surrounding biosimilars will ensure the appropriate use of biopharmaceuticals.

Idiotype vaccination in patients with myeloma reduced circulating myeloma cells (CMC).

BACKGROUND: Circulating myeloma cells (CMC), exhibiting the same immunoglobulin heavy-chain gene rearrangements as the plasma cells, are part of the myeloma clone. In this study, we evaluated the effect of idiotype (Id) vaccination on CMC. PATIENTS AND METHODS: Eleven patients were immunized with the autologous Id in combinations with granulocyte-macrophage colony-stimulating factor and interleukin 12, and followed for CMC by quantitative real-time allele-specific PCR. Id-specific T cells were monitored by proliferation assay, enzyme-linked immunospot (interferon-gamma) assay, and quantitative real-time PCR for cytokines. Regulatory T (T(reg)) cells were analyzed by flow cytometry. RESULTS: CMC were detected in 9 of 11 patients at start of vaccination. In four patients, CMC declined and two had a complete molecular remission. Further two patients had stable levels of CMC during follow-up, while in three patients CMC progressively increased. Six patients had a vaccine-induced Id-specific T-cell response. A significant correlation was observed between reduced/stable levels of CMC and the Id-specific T cells (P < 0.02). The frequency of T(reg) cells was decreased in immune responders, but increased in immune nonresponders (P < 0.05). No significant change in the serum M-protein concentration was, however, observed in any patient. CONCLUSION: Id vaccination reduced CMC, which correlated with vaccine-induced Id-specific T cells. Further studies are warranted to analyze the clinical significance of CMC and clinical effects of Id vaccination.

Pharmacokinetics of the mouse monoclonal antibody 17-1A in cancer patients receiving various treatment schedules.

Twenty-four patients with metastatic colorectal carcinoma were treated with repeated doses (200-500 mg) of the mouse monoclonal antibody (MAb) 17-1A. Four different treatment schedules were used. The total dose was 1, 3.6, 7.6, and 12 g, respectively. Altogether, 263 infusions were administered. The interindividual variations in the maximum serum concentration at 2 h (max2 h) were large. The mean max2 h value after an infusion of 200 mg was 55 +/- 5 micrograms/ml and after 500 mg, 132 +/- 7 micrograms/ml. Max2 h concentration correlated inversely with the half-life of MAb 17-1A (P less than 0.001). The t1/2 beta for 200 mg was 25.9 +/- 1.4 h and after the administration of 500 mg, 19.8 +/- 1.0 h. The total area under the concentration versus time curve increased when high doses were administered on a continuous basis, in comparison with spaced infusions, thus increasing the exposure of the tumor tissues to MAb 17-1A. The pharmacokinetics of mouse MAb 17-1A are best described by a one-compartment model. All patients developed anti-mouse IgG antibodies and most also IgM antibodies. In the more intensive treatment schedules, the IgG antibody response was suppressed. Induction of high titers of anti-mouse antibodies did not cause clinical problems. Neither did they affect the pharmacokinetics of MAb 17-1A at these dose levels. Therapy was tolerated well. The side effects were mild and of short duration. The gastrointestinal adverse reactions were dose dependent and correlated to serum max2 h concentration. Allergic reactions were rare and easily clinically manageable.

Tumor regression in monoclonal antibody-treated patients correlates with the presence of anti-idiotype-reactive T lymphocytes.

Treatment of cancer patients with unconjugated mAbs directed against tumor-associated antigens is considered passive immunotherapy due to the main suggested effector mechanisms: antibody-dependent cellular cytotoxicity, complement-dependent cytolysis, and apoptosis. The therapeutic antibody (ab1) may, however, also give rise to an idiotypic network response, i.e., an immunizing effect. Induced anti-idiotypic antibodies (ab2) mimicking the epitope that ab1 recognizes might subsequently induce an anti-anti-idiotypic humoral (ab3) and T-cell (T3) response recognizing the nominal tumor-associated antigen. Twenty-four patients with metastatic colorectal carcinoma were treated with MAb17-1A against the tumor associated antigen GA733-2 and were analyzed for the induction of T3 cells. Five of the patients responded to mAb therapy with tumor regression. These five patients all had T cells specifically recognizing human ab2 (DNA synthesis) after treatment, while all nonresponding patients lacked such T cells. Four of the five patients with ab2-reactive T cells also showed induction of T cells recognizing GA733-2. The association between T3 cells and tumor regression was highly significant (P = 0.0005). Thus, induction of T3 cells might be an important secondary antitumor effector function of therapy with unconjugated mAbs. Antibody therapy may therefore also be considered active specific immunotherapy.

Tumor-associated antigens common to humans and chemically induced colonic tumors of the rat.

The expression of human tumor-associated antigens CO17-1A, GA73-3, BR55-2, GICA 19-9, and CA50 and of carcinoembryonic antigen was immunohistochemically studied in the colonic mucosa of 70 Sprague-Dawley rats. Fifty were treated with 1,2-dimethylhydrazine (DMH) (with EDTA as a vehicle), ten were treated with EDTA only, and ten were untreated normal rats. The tumors were histogenetically divided as: (a) adenocarcinomas arising from villous adenomas; (b) adenocarcinomas arising from lymphoid-associated mucosa (LAM); and (c) adenocarcinomas arising in flat mucosa. Of 44 colonic adenocarcinomas, BR55-2 was expressed in 41 tumors, CO17-1A in 40 tumors, GA73-3 in 38 tumors, and GICA 19-9 in 38 tumors. CA50 and carcinoembryonic antigen were not expressed in the tumors. The highest antigenic expression (number of cells) was observed in adenocarcinomas arising in villous adenomas and the lowest in those arising in flat mucosa. Adenocarcinomas arising in LAM had an intermediate expression. The expression of these antigens had no correlation to the localization of the tumor and to the differentiation. The expression of these antigens was similar in the non-lymphoid-associated normal colonic mucosa of the untreated, EDTA-treated, and DMH-treated rats. In DMH-treated rats, LAM demonstrated increased expression (number of cells) and increased staining intensity of these tumor-associated antigens. In six of the 50 DMH-treated rats, only LAM expressed carcinoembryonic antigen. CA50 was not expressed in the normal colon of untreated, of EDTA-treated, and of DMH-treated rats, nor was it in DMH-induced tumors. None of the tumor-associated antigens (GICA 19-9 and CA50 and carcinoembryonic antigen) was detected in serum. It is concluded that this animal model would be of value in the preclinical evaluations of monoclonal antibodies for therapy in humans.

Decreased expression of the signal-transducing zeta chains in tumor-infiltrating T-cells and NK cells of patients with colorectal carcinoma.

An impaired immune response is frequently observed in cancer patients and tumor-bearing mice. T-cells from mice with an experimental colon carcinoma were recently shown to express T-cell receptors that completely lacked the signal-transducing molecule CD3 zeta. Here, we have investigated the expression of the signal-transducing molecule zeta on lymphocytes from 14 patients with colorectal carcinomas using flow cytometric analysis of permeabilized cells with a monoclonal antibody (TIA-2; IgG1) specific for the cytoplasmic domain of the zeta chain as well as with immunoprecipitation and analysis on diagonal gel electrophoresis. We demonstrate that T-cells isolated from the tumors of the patients express significantly less CD3 zeta than T-cells in the peripheral blood of the same patients and that the peripheral blood of the patients express decreased levels of zeta chains, as compared to the levels found in lymphocytes from healthy controls. This decreased expression was also observed on zeta chains associated with the low affinity Fc receptor for IgG found in tumor-infiltrating NK cells (Fc gamma RIIIA alpha; CD16).

Immunological characterization of Hodgkin's and non-Hodgkin's lymphoma patients with high antibody titers against Epstein-Barr virus-associated antigens.

We have studied nine Hodgkin's lymphoma (HD) and ten non-Hodgkin's lymphoma (NHL) patients with extraordinarily high anti-viral capsid antigen (VCA) titers (greater than 5120). Controls were 13 HD and 23 NHL patients with anti-VCA titers between 40 and 2560. High anti-VCA titers were present in NHL patients at the time of diagnosis or within 16 months, whereas the rise of anti-VCA titers in HD patients appeared to be a late event during the clinical course of the disease (mean time from diagnosis, 68 months). In particular, we have asked whether the exceptionally high anti-Epstein-Barr virus (EBV) titers in some HD and NHL patients can be correlated to some of the EBV-specific and -nonspecific parameters of cell-mediated immunity. The battery of non-EBV-specific immunological tests included the assessment of natural killer cell activity and the analysis of T-lymphocyte subclasses according to surface markers, together with spontaneous and mitogen-induced DNA synthesis and their helper or suppressor activity on PWM-generated immunoglobulin synthesis. Outgrowth inhibition (Ol) and leukocyte migration inhibition were used to assess EBV-specific cell-mediated immunity. The majority of the high-titer HD and NHL patients showed a drastically reduced OKT4:OKT8 ratio in their peripheral lymphocyte population. Low-titer HD and NHL patients showed no such reduction. There was no strict correlation between the number of OKT8-positive cells and suppressor activity in the functional PWM-induced immunoglobulin production test. Part of the high-titer HD patients showed defective cellular responses in the outgrowth inhibition test, directed against the proliferation of EBV-transformed (EBV-determined nuclear antigen-positive) cells. Some of them showed also a deficient leukocyte migration inhibition response to EBV-determined nuclear antigen but, interestingly, not to early antigen-VCA. In the NHL group, only one of the high-titer patients showed a similar defect. None of the low-titer HD and NHL patients showed such defects.

Cell-mediated immune reactions in three patients with malignant lymphoproliferative diseases in remission and abnormally high Epstein-Barr virus antibody titers.

Two patients with Hodgkin's disease in remission and one chronic lymphatic leukemia patient with extraordinarily high anti-Epstein-Barr virus (EBV) (viral capsid antigen) antibody titers (greater than 10,000) were selected to study a spectrum of cell-mediated immune responses, including natural killer, interferon-boosted killer, antibody-dependent lymphocytotoxicity, and T-cell-mediated reactions. The purpose was to compare these reactions in patients with immunosuppression and a high EBV load who can hold their EBV-carrying cells under control with the corresponding reactions in patients with EBV-carrying lymphoproliferative disease. In contrast to the latter group, the three patients of the present study showed a less profound and less general suppression of the immune responses. Multiple effector mechanisms probably safeguard against the proliferation of EBV-transformed B-cells. Clinically manifest EBV-carrying lymphoproliferative disease occurs only in very severe immunodeficiencies effecting multiple effectors.

Phase II multicenter study of human CD52 antibody in previously treated chronic lymphocytic leukemia. European Study Group of CAMPATH-1H Treatment in Chronic Lymphocytic Leukemia.

PURPOSE: 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). MATERIALS AND 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. CONCLUSION: 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.

CAMPATH-1H monoclonal antibody in therapy for previously treated low-grade non-Hodgkin's lymphomas: a phase II multicenter study. European Study Group of CAMPATH-1H Treatment in Low-Grade Non-Hodgkin's Lymphoma.

PURPOSE: CAMPATH-1H is a human immunoglobulin G1 (IgG1) anti-CD52 monoclonal antibody (MAb) that binds to nearly all B-cell and T-cell lymphomas. We report here the results of a multicenter phase II trial of CAMPATH-1H in patients with advanced, low-grade non-Hodgkin's lymphoma (NHL) who were previously treated with chemotherapy. PATIENTS AND METHODS: Fifty patients who had relapsed (n=25) after or were resistant (n = 25) to chemotherapy were treated with CAMPATH-1H 30 mg administered as a 2-hour intravenous (i.v.) infusion three times weekly for a maximum period of 12 weeks. RESULTS: Six patients (14%) with B-cell lymphomas achieved a partial remission (PR). Patients with mycosis fungoides appeared to respond more frequently (50%; four of eight patients, which included two complete remissions [CRs]). Lymphoma cells were rapidly eliminated from blood in 16 of 17 patients (94%). CR in the bone marrow was obtained in 32% of the patients. Lymphoma skin lesions disappeared completely in four of 10 patients and partial regression was obtained in three patients. Lymphadenopathy and splenomegaly were normalized in only 5% and 15% of patients, respectively. Lymphopenia (< 0.5 x 10(9)/L) occurred in all patients. World Health Organization (WHO) grade IV neutropenia occurred in 14 patients (28%). Opportunistic infections were diagnosed in seven patients and nine patients had bacterial septicemia. Death related to infectious complications occurred in three patients. CONCLUSION: CAMPATH-1H had a significant but limited activity in patients with advanced, heavily pretreated NHL. The most pronounced effects were noted in the blood and bone marrow and in patients with mycosis fungoides. The risk for serious infectious complications needs to be considered for severely ill patients who are evaluated for CAMPATH-1H treatment.

Leukemic cells from progressive B-CLL respond strongly to growth stimulation in vitro.

Isolated leukemic B cells from patients with B-chronic lymphocytic leukemia (B-CLL) were tested for proliferative response in vitro to Staphylococcus Aureus strain Cowan 1 (SAC), IL-2, and low molecular weight (MW) BCGF. Patients were classified according to clinical stage and progressiveness. Ten of eighteen cell populations from patients with progressive B-CLL responded in vitro with a stimulation index (SI) > 20. Only 1/16 non-progressive patients had a proliferative but low response. Normal unfractionated tonsillar B cells responded to SAC and BCGF, whereas normal high buoyant density B cells were unresponsive. After 3 days of stimulation, responding B-CLL cells had multiplied and the B cells expressed CD5, CD19, and weakly CD21. No cells in the responding cultures exhibited CD3 or the EBV nuclear antigen EBNA-1. Cell maturation, measured as IgM secretion, was found in some, but not in all responding B-CLL cultures. Thus, B-CLL cells from patients with progressive disease have the capacity to respond to signaling through surface Ig receptors and to certain T-cell factors which was not the case for B-CLL cells from non-progressive patients. The pattern of in vitro response may be related to disease progression, reflecting a dependency of normal immunoregulatory mechanisms and/or a dysregulation of the growth control in the leukemic cells.

Differences in blood T and NK cell populations between chronic lymphocytic leukemia of B cell type (B-CLL) and monoclonal B-lymphocytosis of undetermined significance (B-MLUS).

T and NK cell blood subpopulations were determined in 33 patients with B-CLL and in 14 patients with B-MLUS by two-color immunofluorescence. CLL patients had significantly higher total numbers of Leu-7+ and CD8+ cells and lower numbers of CD16+/Leu-7- cells as well as a higher Leu-7/CD16 ratio and a lower CD4/CD8 ratio than MLUS patients and control donors. Moreover, MLUS patients exhibited a significantly lower Leu-7/CD16 ratio as well as a higher frequency of CD16+/Leu-7- cells than healthy donors. These results suggest that B-CLL patients have higher numbers of circulating immature NK cells compared to B-MLUS, while B-MLUS patients have a larger proportion of NK cells with a high lytic capability as compared to both CLL and normal controls. The imbalance between CD4+ and CD8+ cells was prominent in CLL with a low CD4/CD8 ratio, but within the upper normal range in MLUS. Differences in immunoregulatory cell subpopulations between B-CLL and B-MLUS might therefore contribute to the different clinical behavior of these two disorders.

Apoptotic tumor cells are superior to tumor cell lysate, and tumor cell RNA in induction of autologous T cell response in B-CLL.

B cell chronic lymphocytic leukemia (B-CLL) is a chronic leukemia manifested by increased numbers of B cells in circulation. The slow, smouldering nature of the disease in a significant proportion of the cases makes it an ideal target for immunotherapy. Dendritic cell (DC)-based immunotherapy is emerging as an exciting modality with significant clinical potential. In this study, three strategies for delivering antigens to DC, namely apoptotic bodies (Apo-DC), tumor lysates, and tumor RNA were studied in an autologous setting. In all six CLL patients, Apo-DC induced higher HLA-restricted, T cell responses than DC pulsed with tumor lysate or RNA. Real-time PCR confirmed higher expression of genes for IL-2 and IFN-gamma in T cells stimulated with Apo-DC. Concurrently, no IL-10 and low IL-4 responses indicated that the immune response was primarily of the Th1 type. Enzyme-linked immunospot assay revealed high IFN-gamma secretion by T cells when Apo-DC was used to stimulate autologous T cells in all patients. Our data suggest that cellular vaccines with DC loaded with apoptotic bodies may be a suitable approach for immunotherapy of B-CLL.

Dendritic cells loaded with apoptotic tumour cells induce a stronger T-cell response than dendritic cell-tumour hybrids in B-CLL.

Dendritic cells (DC) are professional (specialised) antigen-presenting cells that can capture antigen from apoptotic tumour cells and induce MHC class I- and II-restricted responses. Also, DC fused with tumour cells may be effective for immune response induction. Both cell preparations may be considered as vaccine candidates in a therapeutic approach. We examined autologous T-cell activation by DC that had endocytosed leukaemic B-cell apoptotic bodies (Apo-DC) and compared it to the T-cell stimulatory capacity of DC that were fused with tumour cells. Following incubation, 22.6+/-6.2 (mean+/-s.e.m.) of DC had endocytosed leukaemic cells, while the frequency of DC-leukaemic cell hybrids was 10.5+/-2.6%. Apo-DC and hybrid cells both demonstrated the ability to stimulate a tumour-specific T-cell immune response in vitro. A T-cell proliferation response was also observed in four out of five CLL patients when using Apo-DC. However, fusion hybrids lacked the ability to elicit a proliferative response. Apo-DC also induced an IFN-gamma response, as did hybrid cells. The cytokine response induced by Apo-DC was significantly higher than that induced by fusion (P<0.05). This study shows that endocytosed apoptotic tumour cells induced a significantly stronger T-cell response than DC hybrids; and as such should be a better candidate for vaccine production.

S-phase lymphocytes in chronic lymphocytic leukemia (CLL) in relation to immunoglobulin isotypes on the leukemic clone and to disease activity.

The fraction of blood S-phase (S+) lymphocytes from 41 patients with chronic lymphocytic leukemia of B cell type was determined by flow cytometry. The patients were grouped according to the smig isotype pattern of the leukemic cells. Patients with IgM as the predominant smig had higher numbers of S+ lymphocytes than patients with a leukemic clone co-expressing IgM and IgD (p less than 0.001). High relative as well as total numbers of S+ lymphocytes were associated with short therapy-free and overall survival. T cell proliferation was low although significantly higher in active than in indolent disease.

Cellular immune reconstitution after subcutaneous alemtuzumab (anti-CD52 monoclonal antibody, CAMPATH-1H) treatment as first-line therapy for B-cell chronic lymphocytic leukaemia.

Little information is available on long-term immune reconstitution after therapy with alemtuzumab in B-CLL patients. We present long-term follow-up data for blood lymphocyte subsets analysed by flow cytometry in previously untreated B-CLL patients who received alemtuzumab subcutaneously as first-line therapy. All lymphoid subsets were significantly (P<0.001) and profoundly reduced; the median end-of-treatment counts for CD4(+), CD8(+), CD3(-)56(+) (natural killer (NK)), CD3(+)56(+) (NK-T) and CD19(+)5(-) (normal B) cells were 43, 20, 4, 1 and 8 cells/microl, respectively. The median cell count of all subsets remained at <25% of the baseline values for >9 months post-treatment. CD4(+) and CD8(+) levels in blood had reached >100 cells/microl in >50% of the patients at 4 months after the end of treatment. One patient had a cytomegalovirus reactivation and one patient developed Pneumocystis carinii pneumonia during therapy. No opportunistic or other major infections were recorded during unmaintained, long-term follow-up. There was no correlation between the cumulative dose of alemtuzumab and the severity or length of immunosuppression. CD52(-) T-cell subsets occurred during the treatment and comprised >80% of all CD4(+) and CD8(+) cells in the blood at the end of therapy. These subpopulations declined gradually during unmaintained follow-up. The relationship between these observations and the safety/antitumour effects of alemtuzumab is discussed.