Phase 1 study results of the type II glycoengineered humanized anti-CD20 monoclonal antibody obinutuzumab (GA101) in B-cell lymphoma patients.

Whereas the chimeric type I anti-CD20 Ab rituximab has improved outcomes for patients with B-cell malignancies significantly, many patients with non-Hodgkin lymphoma (NHL) remain incurable. Obinutuzumab (GA101) is a glycoengineered, humanized anti-CD20 type II Ab that has demonstrated superior activity against type I Abs in vitro and in preclinical studies. In the present study, we evaluated the safety, efficacy, and pharmacokinetics of GA101 in a phase 1 study of 21 patients with heavily pretreated, relapsed, or refractory CD20(+) indolent NHL. Patients received GA101 in a dose-escalating fashion (3 per cohort, range 50/100-1200/2000 mg) for 8 × 21-day cycles. The majority of adverse events (AEs) were grades 1 and 2 (114 of 132 total AEs). Seven patients reported a total of 18 grade 3 or 4 AEs. Infusion-related reactions were the most common AE, with most occurring during the first infusion and resolving with appropriate management. Three patients experienced grade 3 or 4 drug-related infusion-related reactions. The best overall response was 43%, with 5 complete responses and 4 partial responses. Data from this study suggest that GA101 was well tolerated and demonstrated encouraging activity in patients with previously treated NHL up to doses of 2000 mg. This trial is registered at www.clinicaltrials.gov as NCT00517530.

Obinutuzumab Pretreatment as a Novel Approach to Mitigate Formation of Anti-Drug Antibodies Against Cergutuzumab Amunaleukin in Patients with Solid Tumors.

PURPOSE: The immunocytokine cergutuzumab amunaleukin (CEA-IL2v) showed manageable safety and favorable pharmacodynamics in phase I/Ib trials in patients with advanced/metastatic carcinoembryonic antigen-positive (CEA+) solid tumors, but this was accompanied by a high incidence of anti-drug antibodies (ADA). We examined B-cell depletion with obinutuzumab as a potential mitigation strategy. EXPERIMENTAL DESIGN: Preclinical data comparing B-cell depletion with rituximab versus obinutuzumab are summarized. Substudies of phase I/Ib trials investigated the effect of obinutuzumab pretreatment on ADA development, safety, pharmacodynamics, and antitumor activity of CEA-IL2v ± atezolizumab in patients with advanced/metastatic or unresectable CEA+ solid tumors who had progressed on standard of care. RESULTS: Preclinical data showed superior B-cell depletion with obinutuzumab versus rituximab. In clinical studies, patients received CEA-IL2v monotherapy with (n = 16) or without (n = 6) obinutuzumab pretreatment (monotherapy study), or CEA-IL2v + atezolizumab + obinutuzumab pretreatment (n = 5; combination study). In the monotherapy study, after four cycles (every 2 weeks treatment), 0/15 evaluable patients administered obinutuzumab pretreatment had ADAs versus 4/6 patients without obinutuzumab. Obinutuzumab pretreatment with CEA-IL2v monotherapy showed no new safety signals and pharmacodynamic data suggested minimal impact on T cells and natural killer cells. Conversely, increased liver toxicity was observed in the combination study (CEA-IL2v + atezolizumab + obinutuzumab pretreatment). CONCLUSIONS: These preliminary findings suggest that obinutuzumab pretreatment before CEA-IL2v administration in patients with CEA+ solid tumors may be a feasible and potent ADA mitigation strategy, with an acceptable safety profile, supporting broader investigation of obinutuzumab pretreatment for ADA mitigation in other settings.

A Phase I Study of the Pan-Notch Inhibitor CB-103 for Patients with Advanced Adenoid Cystic Carcinoma and Other Tumors.

PURPOSE: CB-103 selectively inhibits the CSL-NICD (Notch intracellular domain) interaction leading to transcriptional downregulation of oncogenic Notch pathway activation. This dose-escalation/expansion study aimed to determine safety, pharmacokinetics, and preliminary antitumor activity. EXPERIMENTAL DESIGN: Patients ≥18 years of age with selected advanced solid tumors [namely, adenoid cystic carcinoma (ACC)] and hematologic malignancies were eligible. CB-103 was dosed orally in cycles of 28 days at escalating doses until disease progression. Notch-activating mutations were required in a dose confirmatory cohort. Endpoints included dose-limiting toxicities (DLT), safety, tumor response, pharmacokinetics, and pharmacodynamics. Exploratory analyses focused on correlates of Notch and target gene expression. RESULTS: Seventy-nine patients (64, 12 dose-escalation cohorts; 15, confirmatory cohort) enrolled with 54% receiving two or more lines of prior therapy. ACC was the dominant tumor type (40, 51%). Two DLTs were observed [elevated gamma-glutamyl transferase (GGT), visual change]; recommended phase II dose was declared as 500 mg twice daily (5 days on, 2 days off weekly). Grade 3-4 treatment-related adverse events occurred in 15 patients (19%), including elevated liver function tests (LFTs), anemia, and visual changes. Five (6%) discontinued drug for toxicity; with no drug-related deaths. There were no objective responses, but 37 (49%) had stable disease; including 23 of 40 (58%) patients with ACC. In the ACC cohort, median progression-free survival was 2.5 months [95% confidence interval (CI), 1.5-3.7] and median overall survival was 18.4 months (95% CI, 6.3-not reached). CONCLUSIONS: CB-103 had a manageable safety profile and biological activity but limited clinical antitumor activity as monotherapy in this first-in-human study. SIGNIFICANCE: CB-103 is a novel oral pan-Notch inhibitor that selectively blocks the CSL-NICD interaction leading to transcriptional downregulation of oncogenic Notch pathway activation. This first-in-human dose-escalation and -confirmation study aimed to determine the safety, pharmacokinetics, and preliminary antitumor efficacy of CB-103. We observed a favorable safety profile with good tolerability and biological activity but limited clinical single-agent antitumor activity. Some disease stabilization was observed among an aggressive NOTCH-mutant ACC type-I subgroup where prognosis is poor and therapies are critically needed. Peripheral downregulation of select Notch target gene levels was observed with escalating doses. Future studies exploring CB-103 should enrich for patients with NOTCH-mutant ACC and investigate rational combinatorial approaches in tumors where there is limited success with investigational or approved drugs.

Tumor-specific bacteriophages induce tumor destruction through activation of tumor-associated macrophages.

We recently reported that administration of tumor-specific bacteriophages initiates infiltration of neutrophilic granulocytes with subsequent regression of established B16 tumors. The aim of the current study was to investigate the mechanism of action of bacteriophage-induced tumor regression and to examine possible stimulatory effects of bacteriophages on macrophages. We observed that the mechanism of phage-induced tumor regression is TLR dependent as no signs of tumor destruction or neutrophil infiltration were observed in tumors in MyD88(-/-) mice in which TLR signaling is abolished. The microenvironment of bacteriophage-treated tumors was further analyzed by gene profiling through applying a low-density array preferentially designed to detect genes expressed by activated APCs, which demonstrated that the M2-polarized tumor microenvironment switched to a more M1-polarized milieu following phage treatment. Bacteriophage stimulation induced secretion of proinflammatory cytokines in both normal mouse macrophages and tumor-associated macrophages (TAMs) and increased expression of molecules involved in Ag presentation and costimulation. Furthermore, mouse neutrophils selectively migrated toward mediators secreted by bacteriophage-stimulated TAMs. Under these conditions, the neutrophils also exhibited increased cytotoxicity toward B16 mouse melanoma target cells. These results describe a close interplay of the innate immune system in which bacteriophages, located to the tumor microenvironment due to their specificity, stimulate TAMs to secrete factors that promote recruitment of neutrophils and potentiate neutrophil-mediated tumor destruction.

Optimization of skin electroporation in mice to increase tolerability of DNA vaccine delivery to patients.

Electroporation has, during the last years, proven to be a very successful delivery method for DNA vaccines and has now reached clinical evaluation. Although intramuscular electroporation is practical in animal models, intradermal electroporation might be more suitable for clinical administration. Skin is the most accessible organ of the body and has professional antigen-presenting cells in large amounts; thus, skin is an ideal target for DNA vaccine delivery. Moreover, intradermal electroporation has clear clinical benefits such as improved safety and tolerability. This article describes improvements for effective and tolerable DNA delivery to skin. The time of pulse delivery has been shortened by 90% and even pulse programs of 240-ms total duration generate robust immune responses. We show that a single vaccination using an optimized gene delivery generates (i) high and consistent protein expression in vivo, (ii) cytotoxic antigen-specific T cells expressing both IFNgamma and CD107a (lysosomal-associated membrane protein 1). Furthermore, application of a topical anesthetic cream prior to vaccination does not affect the number or function of the antigen-specific T cells induced. This suggests that local anesthesia can be used to further decrease the sensation of pulse delivery in patients.

HER-2/neu mediated down-regulation of MHC class I antigen processing prevents CTL-mediated tumor recognition upon DNA vaccination in HLA-A2 transgenic mice.

To study DNA vaccination directed against human HER-2 in the HHD mouse Tg strain, we created a novel HER-2-expressing syngeneic tumor transplantation model. We found that a DNA vaccine encoding the full length HER-2 DNA protected HHD mice from HER-2(+) tumor challenge by a CTL independent mechanism. A more efficient approach to induce HLA-A2 restricted CTLs, through immunization with a multi-epitope DNA vaccine expressing the HLA-A2 restricted HER-2 369-377, 435-443 and 689-697 epitopes, resulted in high numbers of peptide specific T cells but failed to induce tumor protection. Subsequently we discovered that HER-2 transfected tumor cells down-regulated MHC class I antigen expression and exhibited a series of defects in the antigen processing pathway which impaired the capacity to produce and display MHC class I peptide-ligands to specific CTLs. Our data demonstrate that HER-2 transfection is associated with defects in the MHC class I presentation pathway, which may be the underlying mechanism behind the inability of CTLs to recognize tumors in this HLA-A2 transgenic model. As defective MHC class I presentation may be a common characteristic of HER-2 expressing tumors, vaccines targeting HER-2 should aim at inducing an integrated immune response where also CD4(+) T cells and antibodies are important components.

Interference of macrophage migration inhibitory factor expression in a mouse melanoma inhibits tumor establishment by up-regulating thrombospondin-1.

Macrophage migration inhibitory factor (MIF) is a pleiotropic cytokine with proinflammatory, proangiogenic, and protumorigenic properties. The molecular mechanisms underlying the role of MIF in tumorigenesis and angiogenesis are not well understood. To address these roles, an interfering MIF (iMIF) RNA was stably introduced into the B16-F10 mouse melanoma cell line, reducing MIF mRNA expression 1.6-fold and MIF protein expression 2.8-fold relative to control cells. When iMIF cells were subcutaneously injected into C57BL/6 mice, tumor establishment was significantly delayed and there was a marked absence of intratumoral vasculature in iMIF tumors relative to controls. A comparative gene expression analysis of iMIF and control melanoma cell lines revealed that thrombospondin-1 (TSP-1) mRNA expression was up-regulated 88-fold in the iMIF cells by real-time PCR. A 2-fold increase in TSP-1 protein levels was observed in iMIF cell culture supernatants. These results strongly suggest that the delayed tumor establishment and reduced vasculature in iMIF melanomas are linked to the up-regulation of the antiangiogenic TSP-1. They further define a novel function of MIF as a regulator of TSP-1 in a mouse melanoma model.

Expression of PDX-1 in prostate cancer, prostatic intraepithelial neoplasia and benign prostatic tissue.

Pancreatic duodenal homeobox 1 (PDX-1), a Hox type transcription factor, is necessary for differentiation of exocrine and endocrine pancreas, and regulates insulin gene transcription. PDX-1 expression was studied by immunohistochemistry on a tissue microarray (TMA) of 289 primary prostate cancers (PCa) from radical prostatectomy (RP) specimens with median follow-up of 48.9 months. We separately arrayed benign prostatic tissue, atrophy, high-grade prostatic intraepithelial neoplasia (HGPIN) and PCa from 40 men and also 17 lymph node metastases. Intensity and extent of immunoreactivity and their product (IRp) were evaluated by two independent observers. PDX-1 was overexpressed in cancer vs benign tissue (p<0.001), but also in atrophy and HGPIN vs cancer (p<0.001 and p=0.022, respectively). PDX-1 expression did not correlate with biochemical recurrence, but decreased with higher Gleason pattern (p<0.001) and in metastases vs primary PCa (p<0.001). Weighted kappa for interobserver agreement of intensity, extent and IRp was 0.65, 0.13 and 0.54, respectively. Presence of PDX-1 protein in benign and malignant prostatic tissue was confirmed by Western blot. In view of recent attention to the role of insulin systems in men with PCa, this protein is of interest in the pathogenesis of PCa.

DNA vaccination for prostate cancer.

DNA-based cancer vaccines have been used successfully in mice to induce cytotoxic T lymphocytes (CTLs) specific for prostate antigens. Translation of a prostate-specific antigen (PSA) DNA vaccine into a phase I clinical trial demonstrated that PSA-specific immune responses could be induced but at a significantly lower level compared with those in mice. To enhance the efficacy of DNA vaccination against prostate cancer, we have explored and optimized intradermal electroporation as an effective way of delivering a PSA DNA vaccine. The results demonstrated that intradermal DNA vaccination using low amounts of DNA, followed by two sets of electrical pulses of different length and voltage, effectively induced PSA-specific T cells. Here we describe in detail how to perform intradermal DNA electroporation to induce high gene expression in skin and, more important, how to induce and analyze PSA-specific T cell responses.

Prediction of the Optimal Dosing Regimen Using a Mathematical Model of Tumor Uptake for Immunocytokine-Based Cancer Immunotherapy.

Purpose: Optimal dosing is critical for immunocytokine-based cancer immunotherapy to maximize efficacy and minimize toxicity. Cergutuzumab amunaleukin (CEA-IL2v) is a novel CEA-targeted immunocytokine. We set out to develop a mathematical model to predict intratumoral CEA-IL2v concentrations following various systemic dosing intensities.Experimental Design: Sequential measurements of CEA-IL2v plasma concentrations in 74 patients with solid tumors were applied in a series of differential equations to devise a model that also incorporates the peripheral concentrations of IL2 receptor-positive cell populations (i.e., CD8+, CD4+, NK, and B cells), which affect tumor bioavailability of CEA-IL2v. Imaging data from a subset of 14 patients were subsequently utilized to additionally predict antibody uptake in tumor tissues.Results: We created a pharmacokinetic/pharmacodynamic mathematical model that incorporates the expansion of IL2R-positive target cells at multiple dose levels and different schedules of CEA-IL2v. Model-based prediction of drug levels correlated with the concentration of IL2R-positive cells in the peripheral blood of patients. The pharmacokinetic model was further refined and extended by adding a model of antibody uptake, which is based on drug dose and the biological properties of the tumor. In silico predictions of our model correlated with imaging data and demonstrated that a dose-dense schedule comprising escalating doses and shortened intervals of drug administration can improve intratumoral drug uptake and overcome consumption of CEA-IL2v by the expanding population of IL2R-positive cells.Conclusions: The model presented here allows simulation of individualized treatment plans for optimal dosing and scheduling of immunocytokines for anticancer immunotherapy. Clin Cancer Res; 24(14); 3325-33. ©2018 AACRSee related commentary by Ruiz-Cerdá et al., p. 3236.

Current perspectives in the treatment of advanced prostate cancer.

Prostate cancer (PC) continues to be an important world health problem for men. Patients with locally confined PC are treated with either radiotherapy or surgery. However, treatment of more advanced stages of the disease is problematic. Initially, androgen deprivation offers a period of clinical stability, which is however invariably followed by progression to non-responsiveness to hormonal manipulation. Current management of patients with androgen-independent prostate cancer (AIPC) displays modest response rates and achieves only short-term benefit. Recently, knowledge in the complex pathophysiology of advanced PC has led to the identification of mechanisms and target molecules permitting the introduction of new therapies. Consequently, many investigational treatments are ongoing for AIPC in Phase-II and Phase-III trials aiming at the combination of chemotherapeutic regimens along with immunotherapy targeting PC-associated antigens. Other attractive options are gene therapy, as well as the targeting of survival signaling, differentiation, and apoptosis of the malignant PC cells. Further treatment modalities are directed against the tumor microenvironment, bone metastasis, or both. Collectively, the aforementioned efforts introduce a new era in the management of advanced PC. Novel pharmaceutical compounds and innovative approaches, integrated into the concept of individualized therapy will hopefully, during the next decade, improve the outcome and survival for hundreds of thousands of men worldwide.

Expression of inhibitory receptors on intratumoral T cells modulates the activity of a T cell-bispecific antibody targeting folate receptor.

T-cell bispecific antibodies (TCBs) are a novel therapeutic tool designed to selectively recruit T-cells to tumor cells and simultaneously activate them. However, it is currently unknown whether the dysfunctional state of T-cells, embedded into the tumor microenvironment, imprints on the therapeutic activity of TCBs. We performed a comprehensive analysis of activation and effector functions of tumor-infiltrating T-cells (TILs) in different tumor types, upon stimulation by a TCB targeting folate receptor 1 and CD3 (FolR1-TCB). We observed a considerable heterogeneity in T-cell activation, cytokine production and tumor cell killing upon exposure to FolR1-TCB among different FolR1-expressing tumors. Of note, tumors presenting with a high frequency of PD-1hi TILs displayed significantly impaired tumor cell killing and T-cell function. Further characterization of additional T-cell inhibitory receptors revealed that PD-1hi TILs defined a T-cell subset with particularly high levels of multiple inhibitory receptors compared with PD-1int and PD-1neg T-cells. PD-1 blockade could restore cytokine secretion but not cytotoxicity of TILs in a subset of patients with scarce PD-1hi expressing cells; in contrast, patients with abundance of PD-1hi expressing T-cells did not benefit from PD-1 blockade. Our data highlight that FolR1-TCB is a promising novel immunotherapeutic treatment option which is capable of activating intratumoral T-cells in different carcinomas. However, its therapeutic efficacy may be substantially hampered by a pre-existing dysfunctional state of T-cells, reflected by abundance of intratumoral PD-1hi T-cells. These findings present a rationale for combinatorial approaches of TCBs with other therapeutic strategies targeting T-cell dysfunction.

Extracranial stereotactic radiotherapy for primary and metastatic renal cell carcinoma.

BACKGROUND AND PURPOSE: We investigated the results of using stereotactic radiotherapy (SRT) for 58 patients with renal cell carcinomas (RCC) who were evaluated restrospectively for response rates, local control rates and side effects. PATIENTS AND METHODS: From October 1997 to January 2003, 50 patients suffering from metastatic RCC and eight patients with inoperable primary RCC received high-dose fraction SRT while placed in a stereotactic body-frame. The most common dose/fractionation schedules used were 8 Gyx4, 10 Gyx4 and 15 Gyx3 during approximately 1 week. RESULTS: SRT-treated tumor lesions regressed totally in 30% of the patients at 3-36 months, whereas 60% of the patients had a partial volume reduction or no change after a median follow-up of 37 months (SD 17.4) for censored and 13 months (SD 12.9) for uncensored patients. Side effects were generally mild. Of 162 treated tumors, only three recurred, yielding a local control rate of 90-98%, considering the 8% non-evaluable sites as defined here. For patients with one to three metastases, the time to new spread was 9 months. CONCLUSIONS: Our use of SRT for patients with primary and metastatic RCC yielded a high local control rate with low toxicity. Patients with one to three metastases, local recurrences after nephrectomy or inoperable primary tumors benefited the most, i.e. had fewer distant recurrences (13/23) and longer survival times compared to patients with >3 metastases (24/27 recurrences).

Monocyte enriched apheresis for preparation of dendritic cells (DC) to be used in cellular therapy.

We describe that with one leukapheresis procedure it is feasible to obtain sufficient numbers of monocytes to be utilized in dendritic cell therapies. Twenty-two leukaphereses were performed on eight healthy volunteers and 13 cancer patients, using Cobe Spectra. An on-line sample was drawn as soon as a stable interface was established. The concentration of monocytes in the sample was used to calculate the volume to be collected to reach target numbers of monocytes. A recovery unit was used to calculate the efficacy of the leukaphereses and we demonstrate an efficacy for monocytes correlating with the amount of processed blood.

Progression of Lung Cancer Is Associated with Increased Dysfunction of T Cells Defined by Coexpression of Multiple Inhibitory Receptors.

Dysfunctional T cells present in malignant lesions are characterized by a sustained and highly diverse expression of inhibitory receptors, also referred to as immune checkpoints. Yet, their relative functional significance in different cancer types remains incompletely understood. In this study, we provide a comprehensive characterization of the diversity and expression patterns of inhibitory receptors on tumor-infiltrating T cells from patients with non-small cell lung cancer. In spite of the large heterogeneity observed in the amount of PD-1, Tim-3, CTLA-4, LAG-3, and BTLA expressed on intratumoral CD8(+) T cells from 32 patients, a clear correlation was established between increased expression of these inhibitory coreceptors and progression of the disease. Notably, the latter was accompanied by a progressively impaired capacity of T cells to respond to polyclonal activation. Coexpression of several inhibitory receptors was gradually acquired, with early PD-1 and late LAG-3/BTLA expression. PD-1 blockade was able to restore T-cell function only in a subset of patients. A high percentage of PD-1(hi) T cells was correlated with poor restoration of T-cell function upon PD-1 blockade. Of note, PD-1(hi) expression marked a particularly dysfunctional T-cell subset characterized by coexpression of multiple inhibitory receptors and thus may assist in identifying patients likely to respond to inhibitory receptor-specific antibodies. Overall, these data may provide a framework for future personalized T-cell-based therapies aiming at restoration of tumor-infiltrating lymphocyte effector functions.

Recombinant adenovirus vector activates and protects human monocyte-derived dendritic cells from apoptosis.

The aim of this study was to examine the effect of two of the most commonly used viral vectors, that is, retrovirus and adenovirus, on the antigen presentation of dendritic cells (DCs). DCs were generated from CD34(+) hematopoietic precursors and CD14(+) monocytes of the same prostate cancer patients. Adenoviral transduction of monocyte-derived DCs (MO-DCs) resulted in upregulation of CD80, CD86, and CD83 expression. Adenovirus-transduced MO-DCs were also more potent stimulators of allogeneic lymphocytes, produced increased amounts of the cytokines tumor necrosis factor alpha and interleukin 12 p70, and exhibited increased expression of NF-kappaB and antiapoptotic molecules Bcl-X(L) and Bcl-2. Enhanced expression of the antiapoptotic molecules correlated with increased resistance of adenovirus-transduced MO-DCs to spontaneous as well as Fas-mediated cell death. In contrast to the adenoviral construct, no significant transduction of MO-DCs with the retrovirus could be obtained. Transduction of CD34(+) cell-derived DCs with the retrovirus or the adenovirus did not significantly alter expression of the costimulatory molecules or cytokines studied. At lower stimulation ratios, CD34(+) cell-derived DCs transduced with retrovirus were less potent in their ability to stimulate allogeneic lymphocytes in comparison with nontransduced DCs. Our results indicate that adenoviral vectors may be more suitable for gene delivery to DCs for immunotherapy.

Molecular cytogenetic characterization shows higher genetic homogeneity in conventional renal cell carcinoma compared to other kidney cancers.

In this study seven primary kidney tumors out of 13 were cytogenetically characterized by comparative genomic hybridization (CGH) on the surgical specimens as well as by spectral karyotyping (SKY) analysis after short-term culturing. In two of the seven cases only a normal karyotype was identified. Non-clonal aberrations were observed in four of the seven cases. Overall numerical alterations were more frequent than structural changes. The two structural alterations identified constituted of a deletion of the short arm of chromosome 3 in a conventional renal cell carcinoma (RCC), and a ring chromosome derived from chromosome 8 in a papillary RCC. By CGH gains of copy number were revealed on chromosomes 3, 5, 7, 8q, and 20, while the losses encompassed 3p and 17p. In the papillary RCCs only gains were found. Comparison between SKY and CGH data suggests that the conventional RCCs are genetically more homogeneous than the other types of kidney cancer. In the two papillary RCCs, trisomies of chromosomes 7 and 17 were typical findings. In the transitional cell carcinoma different findings by CGH and SKY would suggest that these tumors constitute a heterogeneous population of tumor cells which could represent different steps of somatic evolution of tumors.

Gene-modified dendritic cells for immunotherapy against cancer.

Dendritic cells (DCs) are described as professional antigen-presenting cells because of their superior T-cell stimulatory capacity. For this reason, attention is being focused on using DCs for clinical applications to treat cancer patients. Although preclinical studies are promising, the majority of clinical studies with DCs have not fulfilled the expectations, yet. The field of DC biology has progressed rapidly over the past years, leading to several options for the improvement of vaccination. Among the different parameters to investigate, this review focuses on the efficiency and biological and functional consequences of different gene transfer methods into different subsets of human DCs. Another important consideration for DC-based vaccination is the elucidation of the role of maturation and apoptosis during DC differentiation.

Allogeneic tumor-dendritic cell fusion vaccines for generation of broad prostate cancer T-cell responses.

Antigen-loaded dendritic cells (DC) are considered potent stimulators of protective immunity. In some studies, DC hybridized with tumor cells have shown promising antitumor responses in mice as well as in humans. A practical drawback of this approach is the limited availability of autologous tumor samples. We investigated the possibility of hybridizing allogeneic prostate cancer cells with human-monocyte-derived DC, and thereby combine the wide repertoire of antigens from the tumor cells with the costimulatory features of the autologous antigen-presenting cells. Three tumor cell lines were used for hybridization using polyethylene glycol (PEG). We show that all three cell lines formed hybrids with DC to the same extent and without significant loss of viability. Restimulation of autologous T cells with these hybrids resulted in generation of tumor-specific IFNgamma-producing T cells with all three tumor cell lines. Similar tumor specificity could not be obtained if T cells were stimulated using a mixture of non-PEG-fused tumor cells and DC. Moreover, these T cells were capable of specific recognition of other tumor cells of prostate cancer origin and autologous DC pulsed with lysate from these prostate cancer cell lines, while a panel of unrelated EBV-transformed B cell lines were not recognized. These results are strongly indicative of the true tumor specificity of these T cells. Our results suggest that DC hybridized with allogeneic prostate cancer cell lines are potent stimulators of a broad prostate-tumor-specific response.

Correlation between HLA-A2 gene frequency, latitude, ovarian and prostate cancer mortality rates.

Molecular-target therapies are novel approaches to the treatment of prostate and ovarian cancer, but to ensure the best response, a very careful selection of patients, based on immunological characteristics, must be performed. We screened for HLA type, 24 patients with advanced ovarian cancer and 26 patients with hormone-refractory prostate cancer, in order to be recruited to vaccine protocols. HLA typing was performed with PCR in ovarian cancer patients and with serological assay in prostate cancer patients. The results were then extended to a population level, comparing the HLA genotype frequencies in Europe with ovarian and prostate cancer mortality rates. An overrepresentation of HLA-A2 phenotype was observed in both patient groups compared to the normal Swedish population (p = 0.01). As it is already known, the higher phenotype frequency of this allele found in Scandinavian countries decreases significantly as one moves further south in Europe. Ovarian and prostate cancer mortality rates decrease as well as the demographic changes in HLA-A2. These observations have to be confirmed by more extended investigations in order to elucidate if HLA-A2 higher frequency is already present at the diagnosis (risk factor) or is selected during the course of the disease (prognostic factor). Moreover, this fact would suggest different strategies for specific immunotherapy in addition to first line conventional treatments.