H. Kim Lyerly

A phase I study of dexosome immunotherapy in patients with advanced non-small cell lung cancer

BackgroundThere is a continued need to develop more effective cancer immunotherapy strategies. Exosomes, cell-derived lipid vesicles that express high levels of a narrow spectrum of cell proteins represent a novel platform for delivering high levels of antigen in conjunction with costimulatory molecules. We performed this study to test the safety, feasibility and efficacy of autologous dendritic cell (DC)-derived exosomes (DEX) loaded with the MAGE tumor antigens in patients with non-small cell lung cancer (NSCLC).MethodsThis Phase I study enrolled HLA A2+ patients with pre-treated Stage IIIb (N = 4) and IV (N = 9) NSCLC with tumor expression of MAGE-A3 or A4. Patients underwent leukapheresis to generate DC from which DEX were produced and loaded with MAGE-A3, -A4, -A10, and MAGE-3DPO4 peptides. Patients received 4 doses of DEX at weekly intervals.ResultsThirteen patients were enrolled and 9 completed therapy. Three formulations of DEX were evaluated; all were well tolerated with only grade 1–2 adverse events related to the use of DEX (injection site reactions (N = 8), flu like illness (N = 1), and peripheral arm pain (N = 1)). The time from the first dose of DEX until disease progression was 30 to 429+ days. Three patients had disease progression before the first DEX dose. Survival of patients after the first DEX dose was 52–665+ days. DTH reactivity against MAGE peptides was detected in 3/9 patients. Immune responses were detected in patients as follows: MAGE-specific T cell responses in 1/3, increased NK lytic activity in 2/4.ConclusionProduction of the DEX vaccine was feasible and DEX therapy was well tolerated in patients with advanced NSCLC. Some patients experienced long term stability of disease and activation of immune effectors

Immunotherapy of cancer with dendritic-cell-based vaccines

Abstract Animal studies have shown that vaccination with genetically modified tumor cells or with dendritic cells (DC) pulsed with tumor antigens are potent strategies to elicit protective immunity in tumor-bearing animals, more potent than “conventional” strategies that have been tested in clinical settings with limited success. While both vaccination strategies are forms of cell therapy requiring complex and costly ex vivo manipulations of the patient’s cells, current protocols using dendritic cells are considerably simpler and would be more widely available. Vaccination with defined tumor antigens presented by DC has obvious appeal. However, in view of the expected emergence of antigen-loss variants as well as natural immunovariation, effective vaccine formulations must contain mixtures of commonly, if not universally, expressed tumor antigens. When, or even if, such common tumor antigens will be identified cannot be, predicted, however. Thus, for the foreseeable future, vaccination with total-tumor-derived material as source of tumor antigens may be preferable to using defined tumor antigens. Vaccination with undefined tumor-derived antigens will be limited, however, by the availability of sufficient tumor tissue for antigen preparation. Because the mRNA content of single cells can be amplified, tumor mRNA, or corresponding cDNA libraries, offer an unlimited source of tumor antigens. DC transfected with tumor RNA were shown to engender potent antitumor immunity in animal studies. Thus, immunotherapy using autologous DC loaded with unfractionated tumor-derived antigens in the form of RNA emerges as a potentially powerful and broadly useful vaccination strategy for cancer patients.

Immunologic monitoring of cancer vaccine therapy: results of a workshop sponsored by the Society for Biological Therapy.

The Society for Biological Therapy held a Workshop last fall devoted to immune monitoring for cancer immunotherapy trials. Participants included members of the academic and pharmaceutical communities as well as the National Cancer Institute and the Food and Drug Administration. Discussion focused on the relative merits and appropriate use of various immune monitoring tools. Six breakout groups dealt with assays of T-cell function, serologic and proliferation assays to assess B cell and T helper cell activity, and enzyme-linked immunospot assay, tetramer, cytokine flow cytometry, and reverse transcription polymerase chain reaction assays of T-cell immunity. General conclusions included: (1) future vaccine studies should be designed to determine whether T-cell dysfunction (tumor-specific and nonspecific) correlated with clinical outcome; (2) tetramer-based assays yield quantitative but not functional data (3) enzyme-linked immunospot assays have the lowest limit of detection (4) cytokine flow cytometry have a higher limit of detection than enzyme-linked immunospot assay, but offer the advantages of speed and the ability to identify subsets of reactive cells; (5) antibody tests are simple and accurate and should be incorporated to a greater extent in monitoring plans; (6) proliferation assays are imprecise and should not be emphasized in future studies; (7) the reverse transcription polymerase chain reaction assay is a promising research approach that is not ready for widespread application; and (8) there is a critical need to validate these assays as surrogates for vaccine potency and clinical effect. Current data and opinion support the use of a functional assay like the enzyme-linked immunospot assay or cytokine flow cytometry in combination with a quantitative assay like tetramers for immune monitoring. At present, assays appear to be most useful as measures of vaccine potency. Careful immune monitoring in association with larger scale clinical trials ultimately may enable the correlation of monitoring results with clinical benefit.

Induction of carcinoembryonic antigen (cea)-specific cytotoxic t-lymphocyte responses In vitro using autologous dendritic cells loaded with cea peptide or cea rna in patients with metastatic malignancies expressing cea

The application of dendritic cells (DC) to the active immunotherapy of cancer currently relies on the generation of potent DC capable of presenting tumor antigens such as carcinoembryonic antigen (CEA). It is unknown whether the T cells of patients with advanced malignancies can be reliably stimulated against tumor antigens by their autologous DC. In this study, starting with the peripheral blood mononuclear cells (PBMC) of patients with metastatic malignancies expressing CEA, autologous DCs were generated in vitro in serum‐free media supplemented with GM‐CSF and IL‐4. The DCs from HLA A2 positive patients were loaded with the CEA peptide CAP‐1 and the DCs from HLA A2 negative patients were depleted of bystander lymphocytes and loaded with mRNA encoding CEA. The DC preparations were tested to determine their phenotype and were used to stimulate autologous PBMC twice, separated by 10–14 days. The stimulated cells were then tested for their ability to lyse CEA‐expressing target cells. We successfully generated an adequate number of DC for a clinical trial from all patients. The harvested DC preparations contained 49% DC and 87% DC if depleted of bystander lymphocytes. Phenotypic analysis showed the typical pattern of CD11c+CD40+CD86+HLA‐DR+ CD80lowCD83lowCD14low. All preparations but one were able to stimulate CEA‐specific cytotoxic T‐lymphocyte (CTL) activity, suggesting that the majority of patients are not anergic to CEA and possess functional DC. The CTL activity was similar for the CEA peptide and CEA RNA‐loaded DC. Int. J. Cancer 82:121–124, 1999.

Induction of Tumor-Specific Cytotoxic T Lymphocytes in Cancer Patients by Autologous Tumor RNA-Transfected Dendritic Cells

ObjectiveTo demonstrate the feasibility of inducing tumor antigen-specific immune responses in patients with metastatic cancer using total tumor RNA-loaded dendritic cells (DCs). Summary Background DataThe authors have shown that DCs transfected with mRNA encoding defined tumor antigens induce tumor antigen-specific T-cell responses in vitro and in vivo. There may be significant advantages to inducing immune responses against the entire repertoire of antigens expressed by a patient’s autologous tumor. MethodsRNA was extracted from a metastatic colon cancer and used to load autologous DCs. The DCs were coincubated with autologous T cells and the cytolytic activity of the T cells was assessed by the ability to lyse the autologous tumor cells. RNA was then extracted from a metastatic lung cancer and used to load autologous DCs, followed by four injections of the DC vaccine given every 4 weeks. Tumor antigen-specific cytotoxic T lymphocyte activity was then evaluated by testing peripheral blood mononuclear cells for their ability to lyse an antigen-expressing target. ResultsDCs transfected with the total RNA content of autologous tumor cells stimulated antigen-specific T-cell responses that are capable of recognizing and lysing autologous, primary tumor cells in vitro. Tumor-specific immune responses were induced in a patient with a carcinoembryonic antigen-expressing adenocarcinoma after immunization with autologous DCs transfected with total tumor RNA. ConclusionsDCs transfected with total tumor RNA may represent a method for inducing immune responses against the entire repertoire of tumor antigens of surgically resected malignancies.

Immunotherapy with Autologous, Human Dendritic Cells Transfected with Carcinoembryonic Antigen mRNA

Immunizations with dendritic cells (DC) transfected with RNA encoding tumor antigens induce potent tumor antigen-specific immune responses in vitro and in murine models. We performed a phase I study of patients with advanced carcinoembryonic antigen (CEA)-expressing malignancies followed by a phase II study of patients with resected hepatic metastases of colon cancer to assess safety and feasibility of administering autologous DC loaded with CEA mRNA. The immunizations were well tolerated. Of the 24 evaluable patients in the dose-escalation phase, there was 1 complete response (by tumor marker), 2 minor responses, 3 with stable disease, and 18 with progressive disease. In the phase II study, 9 of 13 patients have relapsed at a median of 122 days. Evidence of an immunologic response was demonstrated in biopsies of DC injection sites and peripheral blood of selected patients. We conclude that it is feasible and safe to administer mRNA-loaded DC to patients with advanced malignancies.

The Anti-Helminthic Niclosamide Inhibits Wnt/Frizzled1 Signaling

Wnt proteins bind to seven-transmembrane Frizzled receptors to mediate the important developmental, morphogenetic, and stem cell related tissue-regenerative effects of Wnt signaling. Dysregulated Wnt signaling is associated with many cancers. Currently, there are no drug candidates or even tool compounds that modulate Wnt-mediated receptor trafficking, and subsequent Wnt signaling. We examined libraries of FDA-approved drugs for their utility as Frizzled internalization modulators, employing a primary imaged-based GFP fluorescence assay that uses Frizzled1 endocytosis as the readout. We now report that the anti-helminthic niclosamide, a drug used for the treatment of tapeworm, promotes Frizzled1 endocytosis, downregulates Dishevelled-2 protein, and inhibits Wnt3A-stimulated beta-catenin stabilization and LEF/TCF reporter activity. Additionally, following niclosamide-mediated internalization, the Frizzled1 receptor colocalizes in vesicles containing transferrin and agonist-activated beta(2)-adrenergic receptor. Therefore, niclosamide may serve as a negative modulator of Wnt/Frizzled1 signaling by depleting upstream signaling molecules (i.e., Frizzled and Dishevelled) and moreover may provide a valuable means of studying the physiological consequences of Wnt signaling.

Antihelminth Compound Niclosamide Downregulates Wnt Signaling and Elicits Antitumor Responses in Tumors with Activating APC Mutations

Wnt/β-catenin pathway activation caused by adenomatous polyposis coli (APC) mutations occurs in approximately 80% of sporadic colorectal cancers (CRC). The antihelminth compound niclosamide downregulates components of the Wnt pathway, specifically Dishevelled-2 (Dvl2) expression, resulting in diminished downstream β-catenin signaling. In this study, we determined whether niclosamide could inhibit the Wnt/β-catenin pathway in human CRCs and whether its inhibition might elicit antitumor effects in the presence of APC mutations. We found that niclosamide inhibited Wnt/β-catenin pathway activation, downregulated Dvl2, decreased downstream β-catenin signaling, and exerted antiproliferative effects in human colon cancer cell lines and CRC cells isolated by surgical resection of metastatic disease, regardless of mutations in APC. In contrast, inhibition of NF-κB or mTOR did not exert similar antiproliferative effects in these CRC model systems. In mice implanted with human CRC xenografts, orally administered niclosamide was well tolerated, achieved plasma and tumor levels associated with biologic activity, and led to tumor control. Our findings support clinical explorations to reposition niclosamide for the treatment of CRC.

Phase I study of immunization with dendritic cells modified with fowlpox encoding carcinoembryonic antigen and costimulatory molecules.

Purpose: To determine the safety and immunologic and clinical efficacy of a dendritic cell vaccine modified to hyperexpress costimulatory molecules and tumor antigen. Experimental Design: In this phase I study, we administered one or two cycles of four triweekly s.c./intradermal injections of ex vivo generated dendritic cells modified with a recombinant fowlpox vector encoding carcinoembryonic antigen (CEA) and a triad of costimulatory molecules [rF-CEA(6D)-TRICOM]. Controls consisted of immature dendritic cells loaded with tetanus toxoid and a HLA A2–restricted peptide derived from cytomegalovirus pp65 protein. Results: Fourteen patients (11 with colorectal cancer and 3 with non–small cell lung cancer) were enrolled and 12 completed at least one cycle of immunization. There were no grade 3/4 toxicities directly referable to the immunizations. One patient had a decrease in the CEA level from 46 to 6.8 and a minor regression in adenopathy that occurred several months after completion of the immunizations. Five other patients were stable through at least one cycle of immunization (3 months). Direct analysis of peripheral blood mononuclear cells using the ELISpot assay showed an increase in the frequency of CEA-specific T cells in 10 patients (range, 10-541 CEA-specific cells/105 peripheral blood mononuclear cells). There was a trend for a greater peak frequency of CEA-specific T cells among those with either a minor response or a stable disease following at least one cycle of therapy. A second cycle was not associated with higher T-cell frequencies. Cytokine flow cytometry showed CEA-specific immune response among both CD4+ and CD8+ T cells in all immune responders. Conclusion: This immunization strategy is safe and activates potent CEA-specific immune responses.

Dendritic cell-based immunotherapy.

Dendritic cells (DCs) play a crucial role in the induction of antigen-specific T-cell responses, and therefore their use for the active immunotherapy of malignancies has been studied with considerable interest. More than a decade has passed since the publication of the first clinical data of DC-based vaccines, and through this and subsequent studies, a number of important developmental insights have been gleaned. These include the ideal source and type of DCs, the discovery of novel antigens and methods of loading DCs, the role of DC maturation, and the most efficient route of immunization. The generation of immune responses against tumor antigens after DC immunization has been demonstrated, and favorable clinical responses have been reported in some patients; however, it is difficult to pool the results as a whole, and thus the body of data remains inconclusive, in part because of varying DC preparation and vaccination protocols, the use of different forms of antigens, and, most importantly, a lack of rigorous criteria for defining clinical responses. As such, the standardization of clinical and immunologic criteria utilized, as well as DC preparations employed, will allow for the comparison of results across multiple clinical studies and is required in order for future trials to measure the true value and role of this treatment modality. In addition, issues regarding the optimal dose and clinical setting for the application of DC vaccines remain to be resolved, and recent clinical studies have been designed to begin to address these questions.