Phase I/II trial of dendritic cell-based active cellular immunotherapy with DCVAC/PCa in patients with rising PSA after primary prostatectomy or salvage radiotherapy for the treatment of prostate cancer

OBJECTIVE

Immunotherapy of cancer has the potential to be effective mostly in patients with a low tumour burden. Rising PSA (prostate-specific antigen) levels in patients with prostate cancer represents such a situation. We performed the present clinical study with dendritic cell (DC)-based immunotherapy in this patient population.

MATERIALS AND METHODS

The single-arm phase I/II trial registered as EudraCT 2009-017259-91 involved 27 patients with rising PSA levels. The study medication consisted of autologous DCs pulsed with the killed LNCaP cell line (DCVAC/PCa). Twelve patients with a favourable PSA response continued with the second cycle of immunotherapy. The primary and secondary objectives of the study were to assess the safety and determine the PSA doubling time (PSADT), respectively.

RESULTS

No significant side effects were recorded. The median PSADT in all treated patients increased from 5.67 months prior to immunotherapy to 18.85 months after 12 doses (p < 0.0018). Twelve patients who continued immunotherapy with the second cycle had a median PSADT of 58 months that remained stable after the second cycle. In the peripheral blood, specific PSA-reacting T lymphocytes were increased significantly already after the fourth dose, and a stable frequency was detected throughout the remainder of DCVAC/PCa treatment. Long-term immunotherapy of prostate cancer patients experiencing early signs of PSA recurrence using DCVAC/PCa was safe, induced an immune response and led to the significant prolongation of PSADT. Long-term follow-up may show whether the changes in PSADT might improve the clinical outcome in patients with biochemical recurrence of the prostate cancer.

A comprehensive review of immunotherapies in prostate cancer

Prostate cancer is the second most common malignant neoplasm in men worldwide and the fifth cause of cancer-related death. Although multiple new agents have been approved for metastatic castration resistant prostate cancer over the last decade, it is still an incurable disease. New strategies to improve cancer control are needed and agents targeting the immune system have shown encouraging results in many tumor types. Despite being attractive for immunotherapies due to the expression of various tumor associated antigens, the microenvironment in prostate cancer is relatively immunosuppressive and may be responsible for the failures of various agents targeting the immune system in this disease. To date, sipuleucel-T is the only immunotherapy that has shown significant clinical efficacy in this setting, although the high cost and potential trial flaws have precluded its widespread incorporation into clinical practice. Issues with patient selection and trial design may have contributed to the multiple failures of immunotherapy in prostate cancer and provides an opportunity to tailor future studies to evaluate these agents more accurately. We have reviewed all the completed immune therapy trials in prostate cancer and highlight important considerations for the next generation of clinical trials.

Surface engineering tumor cells with adjuvant-loaded particles for use as cancer vaccines

Cell surface engineering is an expanding field and whilst extensive research has been performed decorating cell surfaces with biomolecules, the engineering of cell surfaces with particles has been a largely unexploited area. This study reports on the assembly of cell-particle hybrids where irradiated tumor cells were surface engineered with adjuvant-loaded, biodegradable, biocompatible, polymeric particles, with the aim of generating a construct capable of functioning as a therapeutic cancer vaccine. Successfully assembled cell-particle hybrids presented here comprised either melanoma cells or prostate cancer cells stably adorned with Toll-like receptor-9 ligand-loaded particles using streptavidin-biotin cross-linking. Both cell-particle assemblies were tested in vivo for their potential as therapeutic cancer vaccines yielding promising therapeutic results for the prostate cancer model. The ramifications of results obtained for both tumor models are openly discussed.

Kallikrein-related peptidases (KLKs) as emerging therapeutic targets: focus on prostate cancer and skin pathologies

INTRODUCTION

Tissue kallikrein and the kallikrein-related peptidases (KLKs) constitute a family of 15 homologous secreted serine proteases with trypsin- or chymotrypsin-like activities, which participate in a broad spectrum of physiological procedures. Deregulated expression and/or activation of the majority of the family members have been reported in several human diseases, thereby making KLKs ideal targets for therapeutic intervention.

AREAS COVERED

In the present review, we summarize the role of KLKs in normal human physiology and pathology, focusing on prostate cancer and skin diseases. Furthermore, we discuss the recent advances in the development of KLK-based therapies. A great number of diverse engineered KLKs inhibitors with improved potency, selectivity and immunogenicity have been synthesized by redesigning examples that are endogenous and naturally occurring. Moreover, encouraging results have been documented using KLKs-based vaccines and immunotherapies, as well as KLKs-mediated activation of pro-drugs. Finally, KLKs-targeting aptamers and KLKs-based imaging tools represent novel approaches towards the exploitation of KLKs' therapeutic value.

EXPERT OPINION

The central/critical roles of KLK family in several human pathologies highlight KLKs as attractive molecular targets for developing novel therapeutics.

Economic evaluation of therapeutic cancer vaccines and immunotherapy: a systematic review

Cancer immunotherapy is a rapidly growing field in oncology. One attractive feature of cancer immunotherapy is the purported combination of minimal toxicity and durable responses. However such treatments are often very expensive. Given the wide-spread concern over rising health care costs, it is important for all stakeholders to be well-informed on the cost and cost-effectiveness of cancer immunotherapies. We performed a comprehensive literature review of cost and cost-effectiveness research on therapeutic cancer vaccines and monoclonal antibodies, to better understand the economic impacts of these treatments. We summarized our literature searches into three tables by types of papers: systematic review of economic studies of a specific agent, cost and cost-effectiveness analysis. Our review showed that out of the sixteen immunotherapy agents approved, nine had relevant published economic studies. Five out of the nine studied immunotherapy agents had been covered in systematic reviews. Among those, only one (rituximab for non-Hodgkin lymphoma) was found to be cost-effective. Of the four immunotherapy drugs not covered in systematic reviews (alemtuzumab, ipilimumab, sipuleucel-T, ofatumumab), high incremental cost-effectiveness ratio (ICER) was reported for each. Many immunotherapies have not had economic evaluations, and those that have been studied show high ICERs or frank lack of cost-effectiveness. One major hurdle in improving the cost-effectiveness of cancer immunotherapies is to identify predictive biomarkers for selecting appropriate patients as recipients of these expensive therapies. We discuss the implications surrounding the economic factors involved in cancer immunotherapies and suggest that further research on cost and cost-effectiveness of newer cancer vaccines and immunotherapies are warranted as this is a rapidly growing field with many new drugs on the horizon.

Trial watch: Naked and vectored DNA-based anticancer vaccines

One type of anticancer vaccine relies on the administration of DNA constructs encoding one or multiple tumor-associated antigens (TAAs). The ultimate objective of these preparations, which can be naked or vectored by non-pathogenic viruses, bacteria or yeast cells, is to drive the synthesis of TAAs in the context of an immunostimulatory milieu, resulting in the (re-)elicitation of a tumor-targeting immune response. In spite of encouraging preclinical results, the clinical efficacy of DNA-based vaccines employed as standalone immunotherapeutic interventions in cancer patients appears to be limited. Thus, efforts are currently being devoted to the development of combinatorial regimens that allow DNA-based anticancer vaccines to elicit clinically relevant immune responses. Here, we discuss recent advances in the preclinical and clinical development of this therapeutic paradigm.

Vaccine immunotherapy for prostate cancer: from mice to men

Preclinical studies demonstrated the ability of an adenovirus/PSA (Ad/PSA) vaccine to induce strong anti-PSA immune responses, and these responses were capable of destroying prostate-specific antigen (PSA)-secreting mouse prostate tumors. A series of preclinical studies have demonstrated the superiority of the Ad/PSA vaccine to other PSA vaccines for the induction of anti-PSA immune responses, the ability of Ad/PSA vaccination combined with cytokine gene therapy and the TLR9 agonist CpG to enhance the anti-prostate tumor immunotherapy, and the reduction of negative regulatory elements when the vaccine was combined with 5-fluoruracil administration. A phase I clinical trial of the Ad/PSA vaccine in men with metastatic castrate-resistant prostate cancer demonstrated the safety of the vaccine even at the highest single dose permitted by the FDA. Currently, a phase II trial of the Ad/PSA vaccine is underway treating patients in two protocols. Thus far 81 patients have been enrolled and vaccinated. Early results from the patients evaluated to date demonstrated the induction of anti-PSA T cell responses, and the majority of patients evaluated at this time had demonstrated an increase in PSA doubling times.

Screening and characterization of a novel RNA aptamer that specifically binds to human prostatic acid phosphatase and human prostate cancer cells

Prostatic acid phosphatase (PAP) expression increases proportionally with prostate cancer progression, making it useful in prognosticating intermediate to high-risk prostate cancers. A novel ligand that can specifically bind to PAP would be very helpful for guiding prostate cancer therapy. RNA aptamers bind to target molecules with high specificity and have key advantages such as low immunogenicity and easy synthesis. Here, human PAP-specific aptamers were screened from a 2'-fluoropyrimidine (FY)-modified RNA library by SELEX. The candidate aptamer families were identified within six rounds followed by analysis of their sequences and PAP-specific binding. A gel shift assay was used to identify PAP binding aptamers and the 6N aptamer specifically bound to PAP with a Kd value of 118 nM. RT-PCR and fluorescence labeling analyses revealed that the 6N aptamer bound to PAP-positive mammalian cells, such as PC-3 and LNCaP. IMR-90 negative control cells did not bind the 6N aptamer. Systematic minimization analyses revealed that 50 nucleotide sequences and their two hairpin structures in the 6N 2'-FY RNA aptamer were equally important for PAP binding. Renewed interest in PAP combined with the versatility of RNA aptamers, including conjugation of anti-cancer drugs and nano-imaging probes, could open up a new route for early theragnosis of prostate cancer.

Emerging roles of human prostatic Acid phosphatase

Prostate cancer is one of the most prevalent non-skin related cancers. It is the second leading cause of cancer deaths among males in most Western countries. If prostate cancer is diagnosed in its early stages, there is a higher probability that it will be completely cured. Prostatic acid phosphatase (PAP) is a non-specific phosphomonoesterase synthesized in prostate epithelial cells and its level proportionally increases with prostate cancer progression. PAP was the biochemical diagnostic mainstay for prostate cancer until the introduction of prostate-specific antigen (PSA) which improved the detection of early-stage prostate cancer and largely displaced PAP. Recently, however, there is a renewed interest in PAP because of its usefulness in prognosticating intermediate to high-risk prostate cancers and its success in the immunotherapy of prostate cancer. Although PAP is believed to be a key regulator of prostate cell growth, its exact role in normal prostate as well as detailed molecular mechanism of PAP regulation is still unclear. Here, many different aspects of PAP in prostate cancer are revisited and its emerging roles in other environment are discussed.

A safety and feasibility study of an allogeneic colon cancer cell vaccine administered with a granulocyte-macrophage colony stimulating factor-producing bystander cell line in patients with metastatic colorectal cancer

BACKGROUND

Despite recent advances in earlier detection and improvements in chemotherapy, the 5-year survival rate of patients with metastatic colorectal carcinoma remains poor. Immunotherapy is a potentially effective therapeutic approach to the treatment of colorectal carcinoma. Preclinical studies have supported the antitumor activity of immunization with a granulocyte-macrophage colony-stimulating factor (GM-CSF) producing murine colon tumor cell vaccine.

METHODS

A novel colorectal cancer vaccine composed of irradiated, allogeneic human colon cancer cells and GM-CSF-producing bystander cells was developed and tested in combination with a single intravenous low dose of cyclophosphamide in a phase 1 study of patients with metastatic colorectal cancer.

RESULTS

A total of nine patients were enrolled onto and treated in this study. Six patients had a history of colorectal adenocarcinoma hepatic metastases and underwent curative metastasectomy, while three other patients had unresectable stage IV disease. This study demonstrates the safety and feasibility of this vaccine administered in patients with metastatic colorectal cancer. At last follow-up, the six patients who underwent curative metastasectomy survived longer than 36 months, and four of these six patients were without disease recurrence. Immunologic correlate results suggest that the GM-CSF-producing colon cancer vaccine enhances the production of anti-MUC1 antibodies.

CONCLUSIONS

This vaccine is feasible and safe. Future investigation of the efficacy and antitumor immunity of this vaccine is warranted.

Next-generation cancer vaccine approaches: integrating lessons learned from current successes with promising biotechnologic advances

With the recent approval of sipuleucel-T for metastatic castration-resistant prostate cancer and ipilimumab for metastatic melanoma, there is increasing excitement in the field of cancer immunotherapy. A large number of clinical trials are currently testing various vaccine vectors in a diverse array of cancer types. Which of these strategies will ultimately prove successful has yet to be determined. However, a better understanding of the complex interplay of tumor-specific T cells and the challenges faced at the tumor microenvironment, advances in biotechnology, and lessons learned from prior successes and failures will likely lead to approvals of other therapeutic cancer vaccines.

Assessment of the antigen-specific antibody response induced by mucosal administration of a GnRH conjugate entrapped in lipid nanoparticles

Vaccines administered parenterally have been developed against gonadotrophin-releasing hormone (GnRH) for anti-fertility and anti-cancer purposes. The aim of this study was to demonstrate whether mucosal delivery using GnRH immunogens entrapped in lipid nanoparticles (LNP) could induce anti-GnRH antibody titers. Immunogens consisting of KLH (keyhole limpet hemocyanin) conjugated to either GnRH-I or GnRH-III analogues were entrapped in LNP. Loaded non-ionic surfactant vesicles (NISVs) were administered subcutaneously, while nasal delivery was achieved using NISV in xanthan gum and oral delivery using NISV containing deoxycholate (bilosomes). NISV and bilosomes had similar properties: they were spherical, in the nanometre size range, with a slightly negative zeta potential and surface properties that changed with protein loading and inclusion of xanthan gum. Following immunization in female BALB/c mice, systemic antibody responses were similar for both GnRH-I and GnRH-III immunization. Only nasal delivery proved to be successful in terms of producing systemic and mucosal antibodies.

FROM THE CLINICAL EDITOR

The main research question addressed in this study was whether mucosal delivery using gonadotrophin-releasing hormone immunogens entrapped in lipid nanoparticles could induce anti-GnRH antibody titers. Only nasal delivery proved to be successful in terms of producing systemic and mucosal antibodies with this approach.

Cell-penetrating peptides meditated encapsulation of protein therapeutics into intact red blood cells and its application

Red blood cells (RBCs) based drug carrier appears to be the most appealing for protein drugs due to their unmatched biocompatability, biodegradability, and long lifespan in the circulation. Numerous methods for encapsulating protein drugs into RBCs were developed, however, most of them induce partial disruption of the cell membrane, resulting in irreversible alterations in both physical and chemical properties of RBCs. Herein, we introduce a novel method for encapsulating proteins into intact RBCs, which was meditated by a cell penetrating peptide (CPP) developed in our lab-low molecular weight protamine (LMWP). l-asparaginase, one of the primary drugs used in treatment of acute lymphoblastic leukemia (ALL), was chosen as a model protein to illustrate the encapsulation into erythrocytes mediated by CPPs. In addition current treatment of ALL using different l-asparaginase delivery and encapsulation methods as well as their associated problems were also reviewed.

Cancer immunotherapy: accomplishments to date and future promise

Cancer remains a devastating disease as existing therapies are too often ineffective and toxicities remain unacceptably high. Immunotherapies for cancer offer the promise of the specificity and memory of the immune system against malignant cells to achieve durable cure with minimal toxicity. Beginning with the success of bone marrow transplantation for blood-borne cancers, and the more recent development of monoclonal antibody therapeutics for a variety of tumors, immunotherapies are already among the most successful class of treatments for cancer. Greater understanding of immunoregulatory mechanisms and improved techniques for immune cell manipulation and engineering have led to new immunomodulatory approaches and cell-based therapies for cancer that have generated great excitement within the biomedical community. As these technologies continue to improve, and as new approaches for harnessing the power and specificity of the immune system are developed, immunotherapies will play an increasingly important role in the treatment of cancer. Here, we review the history of immunotherapies for cancer and discuss existing and emerging immunotherapy technologies that hope to translate the promise of immunotherapy into clinical reality.

Bone microenvironment-targeted manipulations for the treatment of osteoblastic metastasis in castration-resistant prostate cancer

INTRODUCTION

Most patients with advanced prostate cancer will develop incurable bone metastasis. Although prostate cancer is the quintessential androgen-dependent neoplastic disease in males, the tumor will ultimately become refractory to androgen ablation treatment. Understanding the complex dialog between prostate cancer and the bone microenvironment has allowed the development of promising treatment strategies.

AREAS COVERED

The present review summarizes the pathophysiology of prostate cancer bone metastasis and provides a concise update on bone microenvironment-targeted therapies for prostate cancer. The current and future prospects and challenges of these strategies are also discussed.

EXPERT OPINION

A wide variety of signaling pathways, bone turnover homeostatic mechanisms and immunoregulatory networks are potential targets for the treatment of metastatic castration-resistant prostate cancer (mCRPC). Anti-survival factor therapy can enhance the efficacy of existing treatment regimens for mCRPC by exploiting the interaction between the bone microenvironment and androgen signaling networks. In addition, many novel bone microenvironment-targeted strategies have produced promising objective clinical responses. Further elucidation of the complex interactions between prostate cancer cells and the bone stroma will open up new avenues for treatment interventions that can produce sustained cancer suppression.

Prostate cancer vaccines: Update on clinical development

Prostate cancer is a common malignancy among elderly men and is essentially incurable once it becomes metastatic. Results from clinical trials testing a panel of specific vaccines in patients with castration-resistant prostate cancer (CRPC) suggest that alternative therapies may one day substitute or support the current gold standard (docetaxel plus prednisone). Here, we summarize the results of germane clinical trials completed during the last 12 y and provide updates on some currently ongoing studies. As it stands, prostate cancer vaccines appear to be safe and capable of generating prostate-specific T lymphocyte responses with potential antitumor activity.

Proposed mechanisms of action for prostate cancer vaccines

Prostate cancer is responsible for the deaths of more than 33,000 American men every year. Once this disease has become metastatic, there is no curative treatment. Alternative therapies to chemotherapy and radical prostatectomy are being increasingly explored. Prostate cancer vaccines--which trigger a tumour-specific cytotoxic-T-lymphocyte-mediated immune attack by the patient's immune system--have been investigated in clinical trials with modest, yet encouraging, results. When developing and administering prostate cancer vaccines, it is critical to consider how vital parameters, such as the stage of disease progression and the nature of adjuvant therapies, could influence treatment outcome. Of particular interest are current and future strategies for diminishing the activity of regulatory T lymphocytes.

α-type-1 polarized dendritic cell-based vaccination in recurrent high-grade glioma: a phase I clinical trial

BACKGROUND

High-grade gliomas including glioblastoma multiforme (GBM) are among the most malignant and aggressive of tumors, and have a very poor prognosis despite a temozolomide-based intensive treatment. Therefore, a novel therapeutic approach to controlling recurrence is needed. In the present study, we investigated the effect of activated dendritic cell (DC) (α-type-1 polarized DC)-based immunotherapy on high-grade glioma patients with the HLA-A2 or A24 genotype.

METHODS

Nine patients with recurrent high-grade gliomas including 7 with GBMs who fulfilled eligibility criteria were enrolled into a phase I study of monocyte-derived DC-based immunotherapy. HLA-genotyping revealed 1 case of HLA-A*0201 and 8 cases of A*2402. Enriched monocytes obtained using OptiPrep(TM) from leukapheresis products on day1, were incubated with GM-CSF and IL-4 in a closed serum-free system, and activated on day6 with TNF-α, IL-1β, IFN-α, IFN-γ, and poly I/C. After pulsing with a cocktail of 5 synthetic peptides (WT-1, HER2, MAGE-A3, and MAGE-A1 or gp100) restricted to HLA-A2 or A24 and KLH, cells were cryopreserved until used. Thawed DCs were injected intradermally in the posterior neck at a dose per cohort of 1.0, 2.0 and 5.0× 10(7)/body.

RESULTS

The frequency of CD14(+) monocytes increased to 44.6% from 11.9% after gradient centrifugation. After a 7-day-incubation with cytokines, the mean percentage of DCs rated as lin(-)HLA-DR(+) in patients was 56.2 ± 19.1%. Most DCs expressed high levels of maturation markers, co-stimulatory molecules and type-1 phenotype (CD11c+HLA-DR+) with a DC1/2 ratio of 35.6. The amount of IL-12 produced from activated DCs was 1025 ± 443 pg/ml per 10(5) cells. All 76 DC injections were well tolerated except for transient liver dysfunction with grade II. Six patients showed positive immunological responses to peptides in an ELISPOT assay, and positive skin tests to peptide-pulsed DC and KLH were recognized in 4 cases. The clinical response to DC injections was as follows :1 SD and 8 PD. Interestingly, the SD patient, given 24 DC injections, showed a long-term recurrence-free and immunological positive response period.

CONCLUSIONS

These results indicate peptide cocktail-treated activated α-type-1 DC-based immunotherapy to be a potential therapeutic tool against recurrent high-grade glioma with mainly HLA-A*2402.

TRIAL REGISTRATION

Current non-randomized investigational trial UMIN-CTR UMIN ID: 000000914.

Over-expressing transporters associated with antigen processing increases antitumor immunity response in prostate cancer

As we know, prostate cancer down-regulates expression of HLA-1 Antigen Processing Machinery (APM) and has defects in the antigen presentation pathway. In vitro, the prostate cancer cell (PC-3 cells) infected with Lentivirus TAP1 can efficiently over-express TAP1 and Tapasin, and HLA-1 was also up-regulated on the surface of the infected cells. The lentivirus TAP1 infection increased the apoptosis rate of PC-3 cells. In addition, with the co-cluture PC-3 cells and lymphocytes, TAP1 augmented the expression of CD3⁺CD8⁺CD38⁺ T cell. Importantly, administration of Lentivirus TAP1 to prostate cancer cells in a xenograft mouse model can prolong survival and increase the CD4⁺ T cells, and CD8⁺ T cells as well as decrease Foxp3⁺ T cells in the tumor microenvironment. In summary, a recombinant lentivirus expressing TAP1 can effectively increase prostate cancer tumor-specific immune response.