Phenotypic and functional analysis in HER2+ targeted therapy of human NK cell subpopulation according to the expression of FcεRIγ and NKG2C in breast cancer patients.

Adaptive NK cells constitute an NK cell subpopulation, which expands after human cytomegalovirus (HCMV) infection. This subpopulation has stronger production of cytokines after CD16 stimulation, longer life and persistence than conventional NK cells and are, therefore, interesting tools for cancer immunotherapy. Since there is limited information on adaptive NK cells in cancer patients, we described this population phenotypically and functionally, by flow cytometry, in the context of HER2 + breast cancer (BC) directed therapy. We assessed HCMV status in 78 patients with BC. We found that, similarly to healthy donors (HD), a high proportion of BC patients were HCMV-positive, and nearly 72% of them had an adaptive NK cell subpopulation characterized by the loss of FcεRIγ intracellular adaptor protein or the presence of NKG2C receptor. However, in BC patients, FcεRIγ- and NKG2C + NK cell populations overlapped to a lesser extent than in HD. Otherwise, no profound phenotypic differences were found between BC patients and HD. Although FcεRIγ- or NKG2C + NK cell subsets from BC patients produced more IFN-γ than their FcεRIγ + or NKG2C- NK cell counterparts, IFN-γ production increased only when NK cells simultaneously expressed FcεRIγ- and NKG2C + , whereas in HD the presence of NKG2C marker was sufficient to display greater functionality. Furthermore, in a group of patients treated with chemotherapy and Trastuzumab plus Pertuzumab, FcεRIγ-NKG2C + and FcεRIγ-NKG2C- NK cells retained greater functionality after treatment than FcεRIγ + NKG2C- NK cells. These results suggest that the presence or magnitude of adaptive NK cell subsets might serve as a key determinant for therapeutic approaches based on antibodies directed against tumor antigens.

Evaluation of paternal lymphocyte immunotherapy and potential biomarker mixed lymphocyte reaction-blocking factor in an Argentinian cohort of women with unexplained recurrent spontaneous abortion and unexplained infertility.

PROBLEM: Analyze the effect of paternal immunotherapy treatment (PIT) in primary and secondary unexplained recurrent spontaneous abortion (URSA) and unexplained infertility (UI). METHODS OF STUDY: A retrospective study analyzed a two-year follow-up between the generation of MLR-Bfs after PIT treatment (or controls first consultation) and a live birth. Recruited patients included primary URSA with two or more miscarriages at <12 weeks gestation, secondary URSA with previous live birth before two or more miscarriages, and UI with inability to conceive after 2 years of regular unprotected intercourse or in vitro fertilizations (IVF). PIT treated were compared with untreated controls. RESULTS: Primary URSA: live birth was 241/416 (58%) versus 64/282 (23%) controls (p < .0001). Up to age 35, success was 158/217 (73%) and 37/144 (26%) controls (p < .0001). With 3 or more previous URSA, success was 90/135 (67%) versus 17/79 (22%) controls (p < .0001). Between ages 36 and 40, success was 69/147(47%) versus 22/98 (22%) controls (p < .0003), with 3 or more previous URSA live birth was 45/95 (47%) versus 6/46 (13%) controls (p < .0001). In UI, live birth was 99/298 (33%) versus 54/263 (21%) in controls (p < .0009) that increased under age 35 to 53/116 (46%) in treated versus 26/101 (26%) controls (p < .0056). In PIT treated, IVF success required a median of 1 (1.37 ± 0.67) versus a median of 3 IVF procedures (2.75 ± 0.84) in controls. CONCLUSION: PIT is a successful treatment for primary and secondary URSA, and UI. PIT reduced the number of IVF required for achieving pregnancy.

Human CD8+HLA-DR+ Regulatory T Cells, Similarly to Classical CD4+Foxp3+ Cells, Suppress Immune Responses via PD-1/PD-L1 Axis.

We have previously identified a human CD8+HLA-DR+ regulatory T cell subset with the ability to suppress proliferation of autologous PBMCs responder cells through cell contact and CTLA-4 co-inhibitory molecule. The present study characterizes the complete phenotype of CD8+HLA-DR+ Treg cells which showed great similarities with classical CD4+ cells expressing forkhead box P3 (FOXP3). The shared features included the expression of programmed cell death protein 1 (PD-1), T-cell immunoreceptor with Ig and ITIM domains (TIGIT), C-C chemokine receptor type 4 and 5 (CCR4 and CCR5), low expression of CD127, and a memory and effector-like phenotype. CD8+HLA-DR+ Treg-induced suppression on CD8+ responder T cells was abrogated by an anti-PD1 neutralizing antibody. Anti-PD-1 did not abrogate the suppressor effect induced on responder CD4+ T cells. In addition, CD8+HLA-DR+ Treg induced a preferential death on responder CD8+ T cells. This effect was not reversed by PD-1 neutralization. After activation, most CD8+HLA-DR+ Treg acquire programmed death-ligand 1 (PD-L1) expression. Interestingly, PD-L1 may induce apoptosis through CD80 expressed on activated CD8+ responder T cells. After PBMCs stimulation, CD8+HLA-DR+ Treg cells showed an increased frequency of IFN-γ and TNFα positive cells and higher degranulation. These data strongly argue against CD8+HLA-DR+ Treg being exhausted cells. Overall, the data presented in this study indicate that CD8+HLA-DR+ Treg and CD4+FOXP3+ Treg share phenotypic and functional features, which may provide cues to similar involvements in the control of antitumor immune responses and autoimmunity.

The tumor antigen N-glycolyl-GM3 is a human CD1d ligand capable of mediating B cell and natural killer T cell interaction.

The expression of N-glycolyl-monosialodihexosyl-ganglioside (NGcGM3) in humans is restricted to cancer cells; therefore, it is a tumor antigen. There are measurable quantities of circulating anti-NGcGM3 antibodies (aNGcGM3 Abs) in human serum. Interestingly, some people have circulating Ag-specific immunoglobulins G (IgGs) that are capable of complement mediated cytotoxicity against NGcGM3 positive cells, which is relevant for tumor surveillance. In light of the chemical nature of Ag, we postulated it as a candidate ligand for CD1d. Furthermore, we hypothesize that the immune mechanism involved in the generation of these Abs entails cross talk between B lymphocytes (Bc) and invariant natural killer T cells (iNKT). Combining cellular techniques, such as flow cytometry and biochemical assays, we demonstrated that CD1d binds to NGcGM3 and that human Bc present NGcGM3 in a CD1d context according to two alternative strategies. We also showed that paraformaldehyde treatment of cells expressing CD1d affects the presentation. Finally, by co-culturing primary human Bc with iNKT and measuring Ki-67 expression, we detected a reproducible increment in the proliferation of the iNKT population when Ag was on the medium. Our findings identify a novel, endogenous, human CD1d ligand, which is sufficiently competent to stimulate iNKT. We postulate that CD1d-restricted Bc presentation of NGcGM3 drives effective iNKT activation, an immunological mechanism that has not been previously described for humans, which may contribute to understanding aNGcGM3 occurrence.

ATP-Induced Inflammation Drives Tissue-Resident Th17 Cells in Metabolically Unhealthy Obesity.

Obesity-induced inflammation is conducted by a metabolic pathway, which eventually causes activation of specialized immune cells and leads to an unresolved inflammatory response within the tissue. For this reason, it is critically important to determine how hypertrophic fat tissue alters T cell balance to drive inflammation. In this study, we identify the purinergic signaling as a novel mechanism driving the adaptive Th17 response in human visceral adipose tissue (VAT) of metabolically unhealthy obese patients. We demonstrate that ATP acting via the P2X7 receptor pathway promotes a Th17 polarizing microenvironment with high levels of IL-1ß, IL-6, and IL-17 in VAT explants from lean donors. Moreover, in vitro blockade of the P2X7 receptor abrogates the levels of these cytokines. These findings are consistent with a greater frequency of Th17 cells in tissue from metabolically unhealthy obese donors, revealed not only by the presence of a baseline Th17-promoting milieu, but also by the higher expression of steadily recognized Th17 markers, such as RORC, IL-17 cytokine, and IL-23R, in comparison with metabolically healthy obese and lean donors. In addition, we demonstrate that CD39 expression on CD4(+)effector T cells represents a novel Th17 marker in the inflamed VAT, which also confers protection against ATP-induced cell death. The manipulation of the purinergic signaling might represent a new therapeutic target to shift the CD4(+)T cell balance under inflammatory conditions.

A Phase I Study of the Anti-Idiotype Vaccine Racotumomab in Neuroblastoma and Other Pediatric Refractory Malignancies.

BACKGROUND: Pediatric neuroectodermal malignancies express N-glycolylated gangliosides including N-glycolyl GM3 (NeuGcGM3) as targets for immunotherapy. PROCEDURE: We evaluated the toxicity and maximum tolerated dose and immunological response of racotumomab, an anti-idiotype vaccine targeting NeuGcGM3 through a Phase I study enrolling children with relapsed or resistant tumors expressing NeuGcGM3. MATERIALS AND METHODS: Drug dose was escalated to three levels (0.15-0.25-0.4 mg) of racotumomab administered intradermally. Each drug level included three patients receiving a total of three doses, every 14 days. A confirmation cohort was added to the highest dose level. Antibody response was assessed upon study entry and at 4-week intervals for at least three immunological determinations for each patient. RESULTS: Fourteen patients were enrolled (10 with neuroblastoma, one with retinoblastoma, one with Wilms' tumor, and two with brainstem glioma). Three patients completed the three drug levels and three were enrolled in the confirmation cohort. One patient died of tumor progression before completing the three applications. Racotumomab was well tolerated. The only side effect observed was grade 1-2 toxicity at the injection site. Racotumomab elicited an IgM and/or IgG antibody response directed against NGcGM3 in nine patients and IgM against racotumomab in 11 of 13 evaluable patients. The maximum tolerated dose was not reached and no dose-limiting toxicity was seen. CONCLUSIONS: Racotumomab vaccination has a favorable toxicity profile up to a dose of 0.4 mg, and most patients elicited an immune response. Its activity as immunotherapy for neuroectodermal malignancies will be tested in further clinical trials.

Overexpression of CD85j in TNBC patients inhibits Cetuximab-mediated NK-cell ADCC but can be restored with CD85j functional blockade.

Clinical studies suggest that triple negative breast cancer (TNBC) patients with epidermal growth factor receptor (EGFR)-expressing tumors could benefit from therapy with Cetuximab, which targets EGFR. NK cells are the primary effectors of antibody (Ab)-dependent cell-mediated cytotoxicity (ADCC) and thus play a role in Ab-based therapies. We have previously described diminished levels of Cetuximab-mediated ADCC in vitro in patients with advanced breast cancer. Here, we investigated the potential causes of this NK-cell functional deficiency. We characterized NK-cell activating/inhibitory receptors in the peripheral blood of breast cancer patients and found CD85j inhibitory receptor overexpression. The capacity of NK cells to perform Cetuximab-triggered ADCC against TNBC cells correlated inversely with CD85j expression, even in the presence of the stimulatory cytokines IL-2 or IL-15. Hence, patients expressing high levels of CD85j had an impaired ability to lyse TNBC cells in the presence of Cetuximab. We also found that CD85j overexpression was associated with HLA-I and soluble HLA-G expression by tumors. A CD85j functional blockade with a CD85j antagonist Ab restored ADCC levels in breast cancer patients and reverted this negative effect. Our data suggest that strategies that overcome the hurdles of immune activation could improve Cetuximab clinical efficacy.

Identification and clinical relevance of naturally occurring human CD8+HLA-DR+ regulatory T cells.

The lack of responsiveness to self and non-self Ags is normally maintained by multiple mechanisms, including the suppressive activities of several T cell subsets. In this study, we show that CD8(+) T cells from both adult peripheral blood and umbilical cord blood mononuclear cells constitutively expressing HLA-DR represent a natural human CD8(+) regulatory T cell subset. Their suppressive effect appears to be cell-to-cell contact dependent and may involve CTLA-4 signaling between neighboring T cells. These regulatory T cells can be expanded in vitro and exhibit a suppressive capacity similar to that observed in ex vivo CD8(+)HLA-DR(+) T cells. The high frequency of CD8(+)HLA-DR(+) T cells that we detected in patients with non-small cell lung cancer deserves further work to confirm their putative suppressor effect within the tumor.

Human memory B cells isolated from blood and tonsils are functionally distinctive.

Human B-cell studies in vitro have routinely used B lymphocytes purified from spleen, blood or tonsils irrespective of potential differences in their immunological traits. In this study, we compared the functional responses of total (CD19(+)) and memory B cells (Bmem; CD19(+)/CD27(+)) isolated from blood and tonsils to different stimuli. Peripheral B cells showed enhanced survival and proliferation compared with their tonsillar equivalents when stimulated for 10 days. Stimulated B cells from both tissues secreted significantly greater amounts of cytokines than unstimulated controls demonstrating their functional responsiveness. Analysis of CD27 expression over time indicated that the conditions that promoted survival and proliferation of peripheral Bmem, caused massive tonsillar Bmem death. Purified tonsillar Bmem failed to expand but rapidly differentiated in antibody secreting cells and subsequently underwent apoptosis. In contrast, circulating Bmem showed delayed activation and differentiation, but exhibited a longer lifespan and active proliferation. In addition, short-term stimulation of tonsillar Bmem resulted in the production of more immunoglobulin G (IgG) than their peripheral counterparts. At later time points, however, IgG production from the different B cells was reversed. Our findings imply that the tissue located and peripheral Bmem have distinct behaviors, indicating organ dependent functional responses that should not be generalizable to all Bmem. This work provides a greater understanding of how Bmem location is coupled to specialized roles of B lymphocytes.

Galectin-1 confers immune privilege to human trophoblast: implications in recurrent fetal loss.

Mechanisms accounting for the protection of the fetal semi-allograft from maternal immune cells remain incompletely understood. In previous studies, we showed that galectin-1 (Gal1), an immunoregulatory glycan-binding protein, hierarchically triggers a cascade of tolerogenic events at the mouse fetomaternal interface. Here, we show that Gal1 confers immune privilege to human trophoblast cells through the modulation of a number of regulatory mechanisms. Gal1 was mainly expressed in invasive extravillous trophoblast cells of human first trimester and term placenta in direct contact with maternal tissue. Expression of Gal1 by the human trophoblast cell line JEG-3 was primarily controlled by progesterone and pro-inflammatory cytokines and impaired T-cell responses by limiting T cell viability, suppressing the secretion of Th1-type cytokines and favoring the expansion of CD4(+)CD25(+)FoxP3(+) regulatory T (T(reg)) cells. Targeted inhibition of Gal1 expression through antibody (Ab)-mediated blockade, addition of the specific disaccharide lactose or retroviral-mediated siRNA strategies prevented these immunoregulatory effects. Consistent with a homeostatic role of endogenous Gal1, patients with recurrent pregnancy loss showed considerably lower levels of circulating Gal1 and had higher frequency of anti-Gal1 auto-Abs in their sera compared with fertile women. Thus, endogenous Gal1 confers immune privilege to human trophoblast cells by triggering a broad tolerogenic program with potential implications in threatened pregnancies.

Anti-ganglioside antibodies induced in chickens by an alum-adsorbed anti-idiotype antibody targeting NeuGcGM3.

Racotumomab is a murine anti-idiotype cancer vaccine targeting NeuGcGM3 on melanoma, breast, and lung cancer. In order to characterize the immunogenicity of alum-adsorbed racotumomab in a non-clinical setting, Leghorn chickens were immunized in dose levels ranging from 25 µg to 1600 µg. Racotumomab was administered subcutaneously in the birds' neck with three identical boosters and serum samples were collected before, during and after the immunization schedule. A strong antibody response was obtained across the evaluated dose range, confirming the immunogenicity of racotumomab even at dose levels as low as 25 µg. As previously observed when using Freund's adjuvant, alum-adsorbed racotumomab induced an idiotype-specific response in all the immunized birds and ganglioside-specific antibodies in 60-100% of the animals. In contrast to the rapid induction anti-idiotype response, detection of ganglioside-specific antibodies in responsive animals may require repeated boosting. Kinetics of anti-NeuGcGM3 antibody titers showed a slight decline 2 weeks after each booster, arguing in favor of repeated immunizations in order to maintain antibody titer. Interestingly, the intensity of the anti-NeuGcGM3 response paralleled that of anti-mucin antibodies and anti-tumor antibodies, suggesting that the in vitro detection of anti-ganglioside antibodies might be a surrogate for an in vivo activity of racotumomab. Taken together, these results suggest that Leghorn chicken immunization might become the means to test the biological activity of racotumomab intended for clinical use.

NGcGM3 ganglioside: a privileged target for cancer vaccines.

Active specific immunotherapy is a promising field in cancer research. N-glycolyl (NGc) gangliosides, and particularly NGcGM3, have received attention as a privileged target for cancer therapy. Many clinical trials have been performed with the anti-NGc-containing gangliosides anti-idiotype monoclonal antibody racotumomab (formerly known as 1E10) and the conjugated NGcGM3/VSSP vaccine for immunotherapy of melanoma, breast, and lung cancer. The present paper examines the role of NGc-gangliosides in tumor biology as well as the available preclinical and clinical data on these vaccine products. A brief discussion on the relevance of prioritization of cancer antigens in vaccine development is also included.

A physiological role for inducible FOXP3(+) Treg cells. Lessons from women with reproductive failure.

We have previously shown a decreased frequency and function of Tregs in women suffering from recurrent spontaneous abortions (RSA). In the current study, we first investigated the expression of FOXP3 after T-cell activation. We observed that expression of FOXP3 in activated PBMCs was already present above baseline before any cell division, indicating that it was induced in cells that were previously negative for this transcription factor. Because RSA women showed a more limited expansion of FOXP3-positive cells, we next assessed the role of IL-2 signaling through STAT5, which is known to be required for generation of inducible Tregs (iTregs). We demonstrated not only that TGF-beta and IL-2 were diminished but also that the IL-2-STAT-5 signaling axis was down regulated in RSA women. Finally, in addition to a limited FOXP3(+) cells expansion in vitro, iTregs from RSA women showed a strikingly lower suppressor activity.

NK cells expressing a progesterone receptor are susceptible to progesterone-induced apoptosis.

It has been proposed that progesterone (P4) induces the suppression of immune responses, particularly during pregnancy. However, knowledge about the mechanisms involved has remained largely elusive. We demonstrate herein that peripheral blood NK (PBNK) cells express both classical progesterone receptor (PR) isoforms and are specifically affected by the actions of P4 through two apparently independent mechanisms. Progesterone induces caspase-dependent PBNK cell death, which is reversed by two different anti-progestins, ZK 98.299 and RU 486, supporting the involvement of classical PR isoforms. It was suggested that CD56(bright)CD16(-) killer Ig-like receptor (KIR)(-) NK cells might represent precursor cells, which, upon activation, acquire the features of a more mature NK subset expressing KIR receptors. The present study demonstrates that PR expression seems to be restricted to more mature KIR(+) PBNK cells. The expression of PR had a functional counterpart in the suppressive effect of P4 on IL-12-induced IFN-gamma secretion. This cytokine suppression was mainly observed in KIR(+) PBNK cells, without affecting the high secretion of IFN-gamma by CD56(bright) PBNK cells. The lack of PR expression on CD56(bright)KIR(-) PBNK cells provides an additional phenotypic marker to test the idea that they might represent the PBNK precursors selectively recruited into the endometrium where they differentiate to become the uterine NK cells. Additionally, these findings may be relevant to NK cell function in viral immunity, human reproduction, and tumor immunity.

Expansion of CD4+CD25+and FOXP3+ regulatory T cells during the follicular phase of the menstrual cycle: implications for human reproduction.

Regulatory T cells (Tregs) are thought to affect the severity of various infectious and autoimmune diseases. The incidence of autoimmune disease is higher in fertile women than in men. Thus, we investigated whether Treg numbers were modulated during the menstrual cycle by sex hormones. In fertile nonpregnant women, we detected an expansion of CD4(+)CD25(+)FOXP3(+) Tregs in the late follicular phase of the menstrual cycle. This increase was tightly correlated with serum levels of estradiol and was followed by a dramatic decrease in Treg numbers at the luteal phase. Women who have had recurrent spontaneous abortions (RSA) showed similarly low numbers of Tregs at both the follicular and luteal phases, comparable to numbers we observed in postmenopausal women. In addition to decreased numbers, Tregs from women with RSA were also functionally deficient, as higher numbers were required to exert a similar magnitude of suppression to CD4(+)CD25(+)FOXP3(+) cells from fertile women. Consequently, reproductive failure might result from the inability of Tregs in women with RSA to expand during the preimplantatory phase combined with their lower functional capacity. Additionally, the modulation of Treg numbers we observed in fertile women suggests that the stage of the menstrual cycle should be taken into account when Treg numbers are investigated clinically.

Implication of RANTES in the modulation of alloimmune response by progesterone during pregnancy.

PROBLEM: Several studies indicate that RANTES (regulated on activation, normal T cell expressed and secreted) is able to downregulate T-cell responses which suggest it might be relevant for fetal tolerance induction. However, the role of RANTES in pregnancy had not been established. Here we investigate RANTES regulation during early pregnancy and potential failures leading to losses of pregnancies. METHOD OF STUDY: RANTES and progesterone levels were determined in sera and feto-placental units from high resorption rate CBA/JxDBA/2 pregnant females and compared with CBA/JxBALB/c normal pregnant mice. RANTES in vitro modulation was also studied in nulliparous, primiparous and multiparous CBA/J and BALB/c cells in response to paternal alloantigen and progesterone stimulation. RESULTS: Nulliparous CBA/J females were quantitatively deficient in RANTES sera levels, whereas pregnancies with male BALB/c or DBA/2 increased its production. However, feto-placental units from CBA/J females are high producers of progesterone and RANTES. CONCLUSION: These data suggest that the beneficial effect of RANTES on feto-maternal interface requires an optimal concentration range and might be modulated by progesterone, hence exacerbated placental expression could be associated with high resorption rate.

Banco Público de Sangre de Cordón Umbilical: etapa inicial del Programa No Relaciona en Argentina / Argentina´s Public Cord Blood Bank: Beginning of the Unrelated Program

La sangre de cordón umbilical (SCU) ofrece una fuente rica de células progenitoras hematopoyéticas para trasplante de médula ósea (TMO). En el año 1996 comenzó en este Hospital un Programa Relacionado de Banco de SCU. Este Programa permite que familias con un niño que padece una enfermedad tratable con TMO almacene la SCU de un hermano por nacer para su futuro uso. Recientemente, el Programa No Relacionado ha sido aprobado y recibió apoyo financiero para adquirir nuevo equipamiento. Este Programa tiene como objetivo colectar y preservar unidades de SCU donadas de manera altruista, que quedan disponible para su uso en TMO alogeneicos en pacientes que no poseen otro donante compatible. Desde agosto de 2005 a enero de 2006 se han inscripto 110 donantes y realizado 96 colectas. El procesamiento de 70 unidades mediante un sistema automatizado permitió recuperar un 76,4 ± 7,4% de las células nucleadas totales (CNT) iniciales. Las unidades presentaron 0,8 ± 0,3 x 10 {elevado a la 9 potencia} CNT finales y un recuento de células CD34+ de 2,79 ± 2,57 x 10 {elevado a la 6º potencia}. El análisis molecular de los antígenos de histocompatibilidad mostró la presencia de alelos característicos de esta problación (A68, B3519, DR08) junto con alelos menos frecuentes en la población de Argentina. El funcionamientos de este Banco nos permitirá aumentar la oferta internacional de unidades con perfil HLA latinoamenicano-hispano, fenotipo escaso en los registros existentes en la actualidad.

Induction of maternal tolerance to fetal alloantigens by RANTES production.

PROBLEM: Previous studies have demonstrated a requirement for RANTES (regulated on activated normal T-cell expressed, and secreted) at immune privileged sites; we have investigated the role of RANTES in the induction of maternal-fetal tolerance. METHOD OF STUDY: Endometrial and peripheral T lymphocytes were obtained from women with recurrent pregnancy losses (RPLs) and fertile women. RANTES modulation by progesterone or paternal alloantigens was measured by enzyme-linked immunosorbent assay or flow cytometry analysis. RESULTS: Progesterone significantly increased intracellular RANTES expression in CD4+ and CD8+ endometrial T cells. Moreover, alloreactive lymphocytes from RPL patients produced lower RANTES levels when compared with those from fertile women. At the local level, treatment with recombinant RANTES induced a decrease in CCR5 and CXCR4 messenger RNA that correlated with an increase in T-bet expression. RPL patients and normally fertile women express RANTES similarly, but differ in their patterns of RANTES receptor expression. CONCLUSION: RANTES may be implicated in the local induction of a Th1-type response necessary for successful implantation. Altered response to RANTES stimulation among some RPL patients may be responsible for poor pregnancy outcomes.

Cellular and humoral immune response to N-Glycolyl-GM3 elicited by prolonged immunotherapy with an anti-idiotypic vaccine in high-risk and metastatic breast cancer patients.

In this study, the immunogenicity and toxicity profile of 1E10, an anti-idiotypic vaccine mimicking the N-glycolyl-GM3 ganglioside, was investigated with an extended vaccination protocol. The year-long vaccination scheme consisted of 6 biweekly intradermal injections (induction phase), followed by 10 monthly boosters (maintenance). Nineteen patients with high-risk (stage III) or metastatic breast cancer were vaccinated with different dose levels of 1E10 (0.5, 1, and 2 mg). The humoral and cellular responses to 1E10 and the targeted ganglioside were assessed at baseline and throughout the treatment. Local skin reactions represented the most common adverse event (National Cancer Institute Toxicity Criteria (NCIC) grades I and II), followed by mild flu-like symptoms lasting for 1 to 2 days. Two patients were removed from the study because of vaccine-related hypersensitivity reactions. A third patient was removed from the study after a transient loss of consciousness with uncertain relation to the vaccine. All patients showed a strong antibody response to the targeted ganglioside. In addition, ganglioside-specific T-cell responses were recorded in 5 of 13 evaluable patients. Vaccination with 1E10 was immunogenic and relatively well tolerated. Because similar results were observed with the 3 tested dose levels, the 0.5-mg dose level was selected for future trials.