Idiotype vaccines for human B-cell malignancies

After twenty years of use in humans, customized idiotypic vaccination yet remains a non-approved, experimental therapeutic option for patients with lymphoma and myeloma. Potentially applicable to all B-cell malignancies whose cells express a clonal immunoglobulin or its epitopes on their surface, this treatment is designed to prevent disease recurrence or progression. Mostly used in follicular lymphoma patients so far, idiotype vaccines have clearly shown biological efficacy, clinical efficacy and clinical benefit in this setting, although no study aiming at regulatory approval of the procedure has been able to meet its main clinical endpoints. In mantle cell lymphoma, only biological efficacy has been proven for idiotypic vaccination, while in multiple myeloma a limited number of studies support the notion of biological and perhaps even clinical efficacy, although no credible evidence of clinical benefit has still emerged. Idiotype vaccines have been produced and administered in a number of substantially different manners. Therefore, the results of most clinical trials cannot be easily compared, and even less pooled together in meaningful meta-analyses. A more creative and yet scientifically sound way to design clinical trials of customized active immunotherapies will be key to the future development of idiotype vaccines, particularly considering that we currently lack any clinical or biological indicator to possibly predict which patients are more likely to respond to idiotypic vaccination from an immunologic point of view. This review aims at summarizing the multifaceted success achieved by idiotype vaccines, as well as at outlining the challenges awaiting them in the near future: how to improve feasibility, immunogenicity and efficacy, as well as how to confirm benefit and gain regulatory approval.

Prolonged idiotypic vaccination against follicular lymphoma

During the last 2 decades, idiotypic vaccination has provided proof of principle of biological efficacy, clinical efficacy and clinical benefit in small follicular lymphoma trials. However, with the exception of anecdotal reports, most patients have received no more than 10 doses of their customised idiotype (Id) vaccine. Therefore, it is not known whether prolonged usage of idiotypic vaccination is safe. Since 2002, 18 previously treated patients with follicular lymphoma have received extended idiotypic vaccination at our institution outside clinical trials. Vaccination was provided as a compassionate alternative to no further treatment, and was meant to be stopped only upon complete consumption of the available patient- and tumor-specific vaccine [Id-keyhole limpet hemocyanin + granulocyte-macrophage colony-stimulating factor (Id-KLH + GM-CSF)], or in case of disease relapse or any serious non-local toxicity. So far, 18 patients have received an average of 18 doses of Id vaccine (median: 17; mean: 18; range: 10-31). Eleven patients are still actively receiving idiotypic vaccination: some of them are now over more than 6 years. Toxicity has been systematically negligible and mostly local. No patient has abandoned the vaccination program because of toxicity. Prolonged idiotypic vaccination with the soluble protein Id-KLH + GM-CSF formulation is safe and well tolerated.

Multivalent 4-1BB binding aptamers costimulate CD8+ T cells and inhibit tumor growth in mice

4-1BB is a major costimulatory receptor that promotes the survival and expansion of activated T cells. Administration of agonistic anti-4-1BB Abs has been previously shown to enhance tumor immunity in mice. Abs are cell-based products posing significant cost, manufacturing, and regulatory challenges. Aptamers are oligonucleotide-based ligands that exhibit specificity and avidity comparable to, or exceeding, that of Abs. To date, various aptamers have been shown to inhibit the function of their cognate target. Here, we have described the development of an aptamer that binds 4-1BB expressed on the surface of activated mouse T cells and shown that multivalent configurations of the aptamer costimulated T cell activation in vitro and mediated tumor rejection in mice. Because aptamers can be chemically synthesized, manufacturing and the regulatory approval process should be substantially simpler and less costly than for Abs. Agonistic aptamers could therefore represent a superior alternative to Abs for the therapeutic manipulation of the immune system.

Clinical benefit associated with idiotypic vaccination in patients with follicular lymphoma

BACKGROUND

Follicular lymphoma is considered incurable, although cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) chemotherapy can induce sequential remissions. A patient's second complete response is typically shorter than that patient's first complete response. Idiotype vaccines can elicit specific immune responses and molecular remissions in patients with follicular lymphoma. However, a clinical benefit has never been formally proven.

METHODS

Thirty-three consecutive follicular lymphoma patients in first relapse received six monthly cycles of CHOP-like chemotherapy. Patients who achieved a second complete response were vaccinated periodically for more than 2 years with autologous lymphoma-derived idiotype protein vaccine. Specific humoral and cellular responses were assessed, and patients were followed for disease recurrence. Statistical tests were two-sided.

RESULTS

Idiotype vaccine could be produced for 25 patients who had a second complete response. In 20 patients (80%), a humoral (13/20) and/or a cellular (18/20) idiotype-specific response was detected. The median duration of the second complete response has not been reached, but it exceeds 33 months (range = 20+ to 51+ months). None of the 20 responders relapsed while undergoing active vaccination. All responders with enough follow-up for the comparison to be made experienced a second complete response that was statistically significantly (P<.0001) longer than both their first complete response (18 of 18 patients) and than the median duration of a CHOP-induced second complete response, i.e., 13 months (20 of 20 patients). The five nonresponders all had a second complete response that was shorter (median = 10 months; range = 8-13 months) than their first complete response (median = 17 months; range = 10-39 months).

CONCLUSIONS

Idiotypic vaccination induced a specific immune response in the majority of patients with follicular lymphoma. Specific immune response was associated with a dramatic and highly statistically significant increase in disease-free survival. This is the first formal demonstration of clinical benefit associated with the use of a human cancer vaccine.

Lipopolysaccharide needs soluble CD14 to interact with TLR4 in human monocytes depleted of membrane CD14

Toll-like receptors recognize specific patterns of microbial components and regulate the activation of both innate and adaptive immunity. TLR4 recognizes lipopolysaccharide (LPS) in monocytes/macrophages with the help of other molecules like CD14 and MD-2, which indicates that the functional LPS receptor forms a large complex. The functional relationship between the components has been the subject of debate, as have the modifications induced by the ligand in the expression of some of these components. Moreover, as for other members of this family of receptors, the possible direct interaction of receptors and their ligands is a matter of discussion. In this paper we address the question of whether the expression of some of the components influences the expression of the rest. Human monocytes in which CD14 has been downregulated through interference in the turnover of the molecule at the Golgi level, show normal membrane TLR4 expression, when compared with control cells. On the other hand, LPS alters membrane TLR4 expression by monocytes devoid of membrane CD14 only in the presence of human serum. The effect of serum is blocked by anti-CD14 monoclonal antibodies, which strongly suggests a functional role for soluble CD14/LPS complexes in the interaction with TLR4. Our data add information on the relationship between the components of the LPS receptor and the characteristics of the interaction of LPS and TLR4 in cells devoid of membrane CD14.

Anti-Inflammatory Cytokines Induce Lipopolysaccharide Tolerance in Human Monocytes Without Modifying Toll-Like Receptor 4 Membrane Expression

Toll-like receptor 4 (TLR4) participates in innate immunity by detecting lipopolysaccharides (LPS) of Gram-negative bacterial cell walls. TLR4 macrophage expression in mice is modulated by LPS. This fact constitutes, at least partially, the molecular basis for LPS tolerance. Very recently, the effect of interferon-gamma (IFN-gamma), a pro-inflammatory cytokine, has been described on TLR4 membrane expression of human monocytes. IFN-gamma up-regulates TLR4 expression and antagonizes the LPS-induced TLR4 down-regulation. These data prompted us to study the expression of membrane TLR4 in human mono- cytes in which LPS tolerance was induced by LPS and by anti-inflammatory cytokines [interleukin-10 (IL-10) and transforming growth factor beta1 (TGFbeta1)]. Data concerning this latter model, and more specifically, the effect of anti-inflammatory cytokines over TLR4 expression, are not available at present. We show here that membrane TLR4 expression in human monocytes falls after LPS exposure. The effect was prolonged for 12 h, but then expression returned to normal levels. The incubation of human monocytes with IL-10, TGFbeta1 or a mixture of both induces no alterations in membrane TLR4 expression. However, these cytokines are able to substitute the tolerizing LPS exposure in order to induce LPS tolerance. Our data help to achieve a better understanding of the way cytokines control the cellular expression of TLR.

Patterns of epithelial cell death during early development of the human inner ear

A light microscopic study of cell death in a developmental series of otic primordia from 23 human embryos (Carnegie stages 9 to 14) was completed. Degenerated cells were noted predominantly in the placode (stages 9 and 10), cup (stages 11 and 12), and otocyst (stages 13 and 14). A systematic camera lucida study of the appearance and topography of degenerating epithelial cells showed four different areas of cell death in the otic primordia that related to 1) invagination and detachment of the otic anlage, 2) early histogenesis of the statoacoustic ganglion, and 3) development of the endolymphatic duct. The possible role of cell death in the morphogenesis of the inner ear related to morphogenetic movements is discussed.

[Farmer's lung. Report of a case (author's transl)]

Asthenia, anorexia, fever, weight loss, dyspnea and cough developed insidiously over 3 months in a patient working in a farm and exposed to moldy organic dusts (hay and alfalfa). Complete recovery occurred when exposure was stopped, but symptoms reappeared when the patient took the same job again. Pulmonary function tests showed reduced compliance and diffusion of gases. The demonstration of precipitating antibodies to moldy hay extracts confirmed the diagnosis of farmer's lung. Eight months after discontinuance of exposure and on steroid therapy the patient was asymptomatic with spirometric values within normal limits. Chest roentgenogram showed a residual finely reticular pattern in the superior lobules. The importance of an early diagnosis and subsequent change of job in order to avoid irreversible pulmonary fibrosis is stressed.

[Bouveret's syndrome. Two new cases (author's transl)]

Pyloro-duodenal obstruction by a gall-stone which has passed through a bilio-digestive fistula (Bouveret's syndrome) is rare. The authors report two cases. The clinical picture is that of pyloric obstruction. The diagnosis, suspected on barium meal, is today confirmed by fibre endoscopy. The treatment is fairly simple: cholecystectomy, removal of the gall stone, closure of the fistula; the prognosis depends on the general context.