Lorenzo Pilla

Identification of a New Subset of Myeloid Suppressor Cells in Peripheral Blood of Melanoma Patients With Modulation by a Granulocyte-Macrophage Colony-Stimulation Factor–Based Antitumor Vaccine

PURPOSE Phenotypic and functional features of myeloid suppressor cells (MSC), which are known to serve as critical regulators of antitumor T-cell responses in tumor-bearing mice, are still poorly defined in human cancers. Here, we analyzed myeloid subsets with suppressive activity present in peripheral blood of metastatic melanoma patients and evaluated their modulation by a granulocyte-macrophage colony-stimulating factor (GM-CSF)--based antitumor vaccine. PATIENTS AND METHODS Stage IV metastatic melanoma patients (n = 16) vaccinated with autologous tumor-derived heat shock protein peptide complex gp96 (HSPPC-96) and low-dose GM-CSF provided pre- and post-treatment whole blood specimens. Peripheral-blood mononuclear cells (PBMCs) were analyzed by flow cytometry, separated into cellular subsets, and used for in vitro proliferation assays. PBMCs from stage-matched metastatic melanoma patients (n = 12) treated with non-GM-CSF-based vaccines (ie, HSPPC-96 alone or interferon alfa/melanoma-derived peptides) or sex- and age-matched healthy donors (n = 16) were also analyzed for comparison. RESULTS The lack of or low HLA-DR expression was found to identify a CD14+ cell subset highly suppressive of lymphocyte functions. CD14+HLA-DR-/lo cells were significantly expanded in all metastatic melanoma patients, whereas they were undetectable in healthy donors. Suppressive activity was mediated by transforming growth factor beta (TGF-beta), whereas no involvement of the arginase and inducible nitric oxide synthase pathways could be detected. CD14+HLA-DR-/lo cells, as well as spontaneous ex vivo release and plasma levels of TGF-beta, were augmented after administration of the HSPPC-96/GM-CSF vaccine. No enhancement of the CD14+-mediated suppressive activity was found in patients receiving non-GM-CSF-based vaccines. CONCLUSION CD14+HLA-DR-/lo cells exerting TGF-beta-mediated immune suppression represent a new subset of MSC potentially expandable by the administration of GM-CSF-based vaccines in metastatic melanoma patients.

Vaccination of Metastatic Melanoma Patients With Autologous Tumor-Derived Heat Shock Protein gp96-Peptide Complexes: Clinical and Immunologic Findings

PURPOSE To determine the immunogenicity and antitumor activity of a vaccine consisting of autologous, tumor-derived heat shock protein gp96-peptide complexes (HSPPC-96, Oncophage; Antigenics, Inc, Woburn, MA) in metastatic (American Joint Committee on Cancer stage IV) melanoma patients. PATIENTS AND METHODS Sixty-four patients had surgical resection of metastatic tissue required for vaccine production, 42 patients were able to receive the vaccine, and 39 were assessable after one cycle of vaccination (four weekly injections). In 21 patients, a second cycle (four biweekly injections) was given because no progression occurred. Antigen-specific antimelanoma T-cell response was assessed by enzyme-linked immunospot (ELISPOT) assay on peripheral blood mononuclear cells (PBMCs) obtained before and after vaccination. Immunohistochemical analyses of tumor tissues were also performed. RESULTS No treatment-related toxicity was observed. Of 28 patients with measurable disease, two had a complete response (CR) and three had stable disease (SD) at the end of follow-up. Duration of CR was 559+ and 703+ days, whereas SD lasted for 153, 191, and 272 days, respectively. ELISPOT assay with PBMCs of 23 subjects showed a significantly increased number of postvaccination melanoma-specific T-cell spots in 11 patients, with clinical responders displaying a high frequency of increased T-cell activity. Immunohistochemical staining of melanoma tissues from which vaccine was produced revealed high expression of both HLA class I and melanoma antigens in seven of eight clinical responders (two with CR, three with SD, and the three with long-term disease-free survival) and in four of 12 nonresponders. CONCLUSION Vaccination of metastatic melanoma patients with autologous HSPPC-96 is feasible and devoid of significant toxicity. This vaccine induced clinical and tumor-specific T-cell responses in a significant minority of patients.

Human Tumor-Released Microvesicles Promote the Differentiation of Myeloid Cells with Transforming Growth Factor-β–Mediated Suppressive Activity on T Lymphocytes

Human tumors constitutively release endosome-derived microvesicles, transporting a broad array of biologically active molecules with potential modulatory effects on different immune cells. Here, we report the first evidence that tumor-released microvesicles alter myeloid cell function by impairing monocyte differentiation into dendritic cells and promoting the generation of a myeloid immunosuppressive cell subset. CD14+ monocytes isolated from healthy donors and differentiated with interleukin (IL)-4 and granulocyte macrophage colony-stimulating factor in the presence of tumor-derived microvesicles turned into HLA-DR(-/low) cells, retaining CD14 expression and failing to up-regulate costimulatory molecules, such as CD80 and CD86. These phenotypic changes were paralleled by a significant release of different cytokines, including IL-6, tumor necrosis factor-alpha, and transforming growth factor-beta (TGF-beta), and a dose-dependent suppressive activity on activated T-cell-proliferation and cytolytic functions, which could be reversed by anti-TGF-beta-neutralizing antibodies. Microvesicles isolated from plasma of advanced melanoma patients, but not from healthy donors, mediated comparable effects on CD14+ monocytes, skewing their differentiation toward CD14+HLA-DR-/low cells with TGF-beta-mediated suppressive activity on T-cell-functions. Interestingly, a subset of TGF-beta-secreting CD14+HLA-DR- cells mediating suppressive activity on T lymphocytes was found to be significantly expanded in peripheral blood of melanoma patients compared with healthy donors. These data suggest the development in cancer patients of an immunosuppressive circuit by which tumors promote the generation of suppressive myeloid cells through the release of circulating microvesicles and without the need for cell-to-cell contact. Therapeutic interventions on the crucial steps of this pathway may contribute to restore tumor/immune system interactions favoring T-cell-mediated control of tumor growth in cancer patients.

Ipilimumab and fotemustine in patients with advanced melanoma (NIBIT-M1): an open-label, single-arm phase 2 trial

BACKGROUND Ipilimumab improves survival of patients with metastatic melanoma, many of whom develop brain metastases. Chemotherapy-induced release of tumour antigens might amplify ipilimumabs antitumour activity. We aimed to investigate the efficacy and safety of ipilimumab plus fotemustine in patients with metastatic melanoma with or without asymptomatic brain metastases. METHODS In our open-label, single-arm phase 2 trial, we enrolled patients 18 years or older with measurable, locally advanced, unresectable stage III or stage IV melanoma between July 6, 2010, and April 14, 2011. Eligible patients had a life expectancy of 16 weeks or more and an Eastern Cooperative Oncology Group performance status of 1 or less, and could have received a maximum of one previous line of chemotherapy. Participants received induction treatment of 10 mg/kg intravenous ipilimumab every 3 weeks to a total of four doses, and 100 mg/m(2) intravenous fotemustine weekly for 3 weeks and then every 3 weeks from week 9 to week 24. Patients with a confirmed clinical response were eligible for maintenance treatment from week 24, with ipilimumab every 12 weeks and fotemustine every 3 weeks. The primary endpoint was the proportion of patients with immune-related disease control as established with immune-related response criteria. Analyses were done per protocol. This trial is registered with EudraCT, number 2010-019356-50, and with ClinicalTrials.gov, number NCT01654692. FINDINGS 86 patients were eligible for treatment, of whom 20 had asymptomatic brain metastases at baseline. 40 patients in the study population achieved disease control (46·5%, 95% CI 35·7-57·6), as did ten with brain metastases (50·0%, 27·2-72·8). 47 patients (55%) had grade 3 or 4 treatment-related adverse events, of which the most common was myelotoxicity (thrombocytopenia in 21 [24%] patients and neutropenia in 16 [19%]). The most common grade 3 or 4 immune-related adverse events were hepatic: 21 patients (24%) had grade 3 or 4 increases in concentrations of alanine aminotransferase or aspartate aminotransferase. INTERPRETATION The combination of ipilimumab plus fotemustine has clinical activity in patients with metastatic melanoma, including those with brain metastases. FUNDING Bristol-Myers Squibb.

A phase II trial of vaccination with autologous, tumor-derived heat-shock protein peptide complexes Gp96, in combination with GM-CSF and interferon-α in metastatic melanoma patients

The aim of this study was to determine the immunogenicity and antitumor activity of autologous, tumor-derived heat shock protein gp96-peptide complex vaccine (HSPPC-96; Oncophage®) given with GM-CSF and IFN-α in pre-treated metastatic (AJCC stage IV) melanoma patients. Patients underwent surgical resection of metastatic lesions for HSPPC-96 production. HSPPC-96 was administered subcutaneously (s.c.) in four weekly intervals (first cycle). Patients with more available vaccine and absence of progressive disease received four additional injections in 2-week intervals (second cycle) or more. GM-CSF was given s.c. at the same site at days –1, 0 and +1, while IFN-α (3 MU) was administered s.c. at a different site at days +4 and +6. Antigen-specific anti-melanoma T and NK lymphocyte response was assessed by enzyme-linked immunospot assay on peripheral blood mononuclear cells obtained before and after vaccination. Thirty-eight patients were enrolled, 20 received at least four injections (one cycle) of HSPPC-96 and were considered assessable. Toxicity was mild and most treatment-related adverse events were local erythema and induration at the injection site. Patients receiving at least four injections of HSPPC-96 were considered evaluable for clinical response: of the 18 patients with measurable disease post surgery, 11 showed stable disease (SD). The ELISPOT assay revealed an increased class I HLA-restricted T and NK cell-mediated post-vaccination response in 5 out of 17 and 12 out of the 18 patients tested, respectively. Four of the five class I HLA-restricted T cell responses fall in the group of SD patients. Vaccination with autologous HSPPC-96 together with GM-CSF and IFN-α is feasible and accompanied by mild local and systemic toxicity. Both tumor-specific T cell-mediated and NK cell responses were generated in a proportion of patients. Clinical activity was limited to SD. However, both immunological and clinical responses were not improved as compared with those recorded in a previous study investigating HSPPC-96 monotherapy.

Human Tumor-Derived Heat Shock Protein 96 Mediates In Vitro Activation and In Vivo Expansion of Melanoma- and Colon Carcinoma-Specific T Cells

Heat shock proteins (hsp) 96 play an essential role in protein metabolism and exert stimulatory activities on innate and adaptive immunity. Vaccination with tumor-derived hsp96 induces CD8+ T cell-mediated tumor regressions in different animal models. In this study, we show that hsp96 purified from human melanoma or colon carcinoma activate tumor- and Ag-specific T cells in vitro and expand them in vivo. HLA-A*0201-restricted CD8+ T cells recognizing Ags expressed in human melanoma (melanoma Ag recognized by T cell-1 (MART-1)/melanoma Ag A (Melan-A)) or colon carcinoma (carcinoembryonic Ag (CEA)/epithelial cell adhesion molecule (EpCAM)) were triggered to release IFN-γ and to mediate cytotoxic activity by HLA-A*0201-matched APCs pulsed with hsp96 purified from tumor cells expressing the relevant Ag. Such activation occurred in class I HLA-restricted fashion and appeared to be significantly higher than that achieved by direct peptide loading. Immunization with autologous tumor-derived hsp96 induced a significant increase in the recognition of MART-1/Melan-A27–35 in three of five HLA-A*0201 melanoma patients, and of CEA571–579 and EpCAM263–271 in two of five HLA-A*0201 colon carcinoma patients, respectively, as detected by ELISPOT and HLA/tetramer staining. These increments in Ag-specific T cell responses were associated with a favorable disease course after hsp96 vaccination. Altogether, these data provide evidence that hsp96 derived from human tumors can present antigenic peptides to CD8+ T cells and activate them both in vitro and in vivo, thus representing an important tool for vaccination in cancer patients.

Immunization of Stage IV Melanoma Patients with Melan-A/MART-1 and gp100 Peptides plus IFN-α Results in the Activation of Specific CD8+ T Cells and Monocyte/Dendritic Cell Precursors

The use of IFN-alpha in clinical oncology has generally been based on the rationale of exploiting its antiproliferative and antiangiogenic activities. However, IFN-alpha also exhibits enhancing effects on T-cell and dendritic cell functions, which may suggest a novel use as a vaccine adjuvant. We have carried out a pilot phase I-II trial to determine the effects of IFN-alpha, administered as an adjuvant of Melan-A/MART-1:26-35(27L) and gp100:209-217(210M) peptides, on immune responses in stage IV melanoma patients. In five of the seven evaluable patients, a consistent enhancement of CD8(+) T cells recognizing modified and native MART-1 and gp100 peptides and MART-1(+)gp100(+) melanoma cells was observed. Moreover, vaccination induced an increase in CD8(+) T-cell binding to HLA tetramers containing the relevant peptides and an increased frequency of CD45RA(+)CCR7(-) (terminally differentiated effectors) and CD45RA(-)CCR7(-) (effector memory) cells. In all patients, treatment augmented significantly the percentage of CD14(+) monocytes and particularly of the CD14(+)CD16(+) cell fraction. An increased expression of CD40 and CD86 costimulatory molecules in monocytes was also observed. Notably, postvaccination monocytes from two of the three patients showing stable disease or long disease-free survival showed an enhanced antigen-presenting cell function and capability to secrete IP10/CXCL10 when tested in mixed leukocyte reaction assays, associated to a boost of antigen and melanoma-specific CD8(+) T cells. Although further clinical studies are needed to show the adjuvant activity of IFN-alpha, the present data represent an important starting point for considering a new clinical use of IFN-alpha and new immunologic end points, potentially predictive of clinical response.

Role of Cross-Talk between IFN-α-Induced Monocyte-Derived Dendritic Cells and NK Cells in Priming CD8+ T Cell Responses against Human Tumor Antigens

In the present study we evaluated the role of IFN-α in the generation of dendritic cells (IFN-DCs) with priming activity on CD8+ T lymphocytes directed against human tumor Ags. A 3-day treatment of monocytes, obtained as adherent PBMCs from HLA-A*0201+ healthy donors, with IFN-α and GM-CSF led to the differentiation of DCs displaying a semimature phenotype, but promptly inducing CD8+ T cell responses after one in vitro sensitization with peptides derived from melanoma (gp100209–217 and MART-1/Melan-A27–35) and adenocarcinoma (CEA605–613) Ags. However, these features were lost when IFN-DCs were generated from immunosorted CD14+ monocytes. The ability of adherent PBMCs to differentiate into IFN-DCs expressing higher levels of costimulatory molecules and exerting efficient T cell priming capacity was associated with the presence of contaminating NK cells, which underwent phenotypic and functional activation upon IFN-α treatment. NK cell boost appeared to be mediated by both direct and indirect (i.e., mediated by IFN-DCs) mechanisms. Experiments performed to prove the role of contaminating NK cells in DC differentiation showed that IFN-DCs generated in the absence of NK were phenotypically less mature and could not efficiently prime antitumor CD8+ lymphocytes. Reciprocally, IFN-DCs raised from immunosorted CD14+ monocytes regained their T cell priming activity when NK cells were added to the culture before IFN-α and GM-CSF treatment. Together, our data suggest that the ability of IFN-DCs to efficiently prime anti-tumor CD8+ T lymphocytes relied mostly on the positive cross-talk occurring between DCs and NK cells upon stimulation with IFN-α.

Escape strategies and reasons for failure in the interaction between tumour cells and the immune system: how can we tilt the balance towards immune-mediated cancer control?

The last decade has witnessed an exponential increase in the attempts to demonstrate that adaptive immunity can effectively detect cancer cells and impair their growth invivo in cancer patients. However, clinical trials of immunotherapy with a broad array of immunisation strategies have depicted a rather disappointing scenario, suggesting that successful control of tumour growth by immunotherapeutic treatments may not be an easy task to achieve. The attention of tumour immunologists has thus been switched to the potential reasons of failure, and extensive efforts are being made in defining the cellular and molecular pathways interfering with the capacity of the immune system to develop powerful immunological reactions against tumour cells. Although many of these pathways have been well characterised in murine models, little and controversial information about their role in determining neoplastic progression in cancer patients is available. This d-iscrepancy at the moment represents one of the major limitations in understanding the obstacles to the invivo development of protective Tcell-m-ediated immune responses against tumours, and how pharmacological or biological interventions aimed at bypassing tumour escape mechanisms would indeed result in a clinical benefit. The study of the reasons for the failure of the immune system to control tumour growth, which have to be ascribed to highly interconnected phenomena occurring at both tumour and immune levels, could in the near future provide adequate tools to fight c-ancer by finely tuning the host environment through biological therapies.

Heat shock proteins and their use as anticancer vaccines

Despite the improvement in the outcome of anticancer therapy achieved during the last few years, several metastatic tumors remain resistant to therapy. This is particularly true for metastatic melanoma, renal and lung carcinoma, and, although to a lesser extent, for colorectal carcinoma. For these