Özcan Met

Adoptive cell therapy with autologous tumor infiltrating lymphocytes and low-dose Interleukin-2 in metastatic melanoma patients

BackgroundAdoptive cell therapy may be based on isolation of tumor-specific T cells, e.g. autologous tumor infiltrating lymphocytes (TIL), in vitro activation and expansion and the reinfusion of these cells into patients upon chemotherapy induced lymphodepletion. Together with high-dose interleukin (IL)-2 this treatment has been given to patients with advanced malignant melanoma and impressive response rates but also significant IL-2 associated toxicity have been observed. Here we present data from a feasibility study at a Danish Translational Research Center using TIL adoptive transfer in combination with low-dose subcutaneous IL-2 injections.MethodsThis is a pilot trial (ClinicalTrials.gov identifier: NCT00937625) including patients with metastatic melanoma, PS ≤1, age <70, measurable and progressive disease and no involvement of the central nervous system. Six patients were treated with lymphodepleting chemotherapy, TIL infusion, and 14 days of subcutaneous low-dose IL-2 injections, 2 MIU/day.ResultsLow-dose IL-2 considerably decreased the treatment related toxicity with no grade 3–4 IL-2 related adverse events. Objective clinical responses were seen in 2 of 6 treated patients with ongoing complete responses (30+ and 10+ months), 2 patients had stable disease (4 and 5 months) and 2 patients progressed shortly after treatment. Tumor-reactivity of the infused cells and peripheral lymphocytes before and after therapy were analyzed. Absolute number of tumor specific T cells in the infusion product tended to correlate with clinical response and also, an induction of peripheral tumor reactive T cells was observed for 1 patient in complete remission.ConclusionComplete and durable responses were induced after treatment with adoptive cell therapy in combination with low-dose IL-2 which significantly decreased toxicity of this therapy.

Long-Lasting Complete Responses in Patients with Metastatic Melanoma after Adoptive Cell Therapy with Tumor-Infiltrating Lymphocytes and an Attenuated IL2 Regimen.

Purpose: Adoptive cell transfer therapy (ACT) based on autologous tumor-infiltrating lymphocytes (TIL) has achieved impressive clinical results in several phase I and II trials performed outside of Europe. Although transient, the toxicities associated with high-dose (HD) bolus IL2 classically administered together with TILs are severe. To further scrutinize whether similar results can be achieved with lower doses of IL2, we have carried out a phase I/II trial of TIL transfer after classical lymphodepleting chemotherapy followed by an attenuated IL2 regimen. Experimental Design: Twenty-five patients with progressive treatment-refractory metastatic melanoma, good clinical performance, age < 70 years, and at least one resectable metastasis were eligible. TIL infusion was preceded by standard lymphodepleting chemotherapy and followed by attenuated doses of IL2 administered in an intravenous, continuous decrescendo regimen (ClinicalTrials.gov Identifier: NCT00937625). Results: Classical IL2-related toxicities were observed but patients were manageable in a general oncology ward without the need for intervention from the intensive care unit. RECIST 1.0 evaluation displayed three complete responses and seven partial responses (ORR 42%). Median overall survival was 21.8 months. Tumor regression was associated with a higher absolute number of infused tumor-reactive T cells. Moreover, induction and persistence of antimelanoma T-cell responses in the peripheral blood was strongly correlated to clinical response to treatment. Conclusions: TIL-ACT with a reduced IL2 decrescendo regimen results in long-lasting complete responses in patients with treatment-refractory melanoma. Larger randomized trials are needed to elucidate whether clinical efficacy is comparable with TIL-ACT followed by HD bolus IL2. Clin Cancer Res; 22(15); 3734–45. ©2016 AACR.

HLA-Restricted CTL That Are Specific for the Immune Checkpoint Ligand PD-L1 Occur with High Frequency in Cancer Patients

PD-L1 (CD274) contributes to functional exhaustion of T cells and limits immune responses in patients with cancer. In this study, we report the identification of an human leukocyte antigen (HLA)-A2-restricted epitope from PD-L1, and we describe natural, cytolytic T-cell reactivity against PD-L1 in the peripheral blood of patients with cancer and healthy individuals. Notably, PD-L1-specific T cells were able not only to recognize and kill tumor cells but also PD-L1-expressing dendritic cells in a PD-L1-dependent manner, insofar as PD-L1 ablation rescued dendritic cells from killing. Furthermore, by incubating nonprofessional antigen-presenting cells with long peptides from PD-L1, we found that PD-L1 was rapidly internalized, processed, and cross-presented by HLA-A2 on the cell surface. Apparently, this cross-presentation was TAP-independent, as it was conducted not only by B cells but in addition by TAP-deficient T2-cells. This is intriguing, as soluble PD-L1 has been detected in the sera from patients with cancer. PD-L1-specific CTL may boost immunity by the killing of immunosuppressive tumor cells as well as regulatory cells. However, PD-L1-specific CTLs may as well suppress immunity by the elimination of normal immune cells especially PD-L1 expressing mature dendritic cells.

T-cell Responses to Oncogenic Merkel Cell Polyomavirus Proteins Distinguish Patients with Merkel Cell Carcinoma from Healthy Donors

Purpose: Merkel cell carcinoma (MCC) is a highly aggressive skin cancer with strong evidence of viral carcinogenesis. The association of MCC with the Merkel cell polyomavirus (MCPyV) may explain the explicit immunogenicity of MCC. Indeed, MCPyV-encoded proteins are likely targets for cytotoxic immune responses to MCC as they are both foreign to the host and necessary to maintain the oncogenic phenotype. However, to date only a single MCPyV-derived CD8 T-cell epitope has been described, thus impeding specific monitoring of T-cell responses to MCC. Method: To overcome this limitation, we scanned the MCPyV oncoprotein large T and small T antigens and the virus capsid protein VP1 for potential T-cell epitopes, and tested for MHC class I affinity. We confirmed the relevance of these epitopes using a high-throughput platform for T-cell enrichment and combinatorial encoding of MHC class I multimers. Results: In peripheral blood from 38 patients with MCC and 30 healthy donors, we identified 53 MCPyV-directed CD8 T-cell responses against 35 different peptide sequences. Strikingly, T-cell responses against oncoproteins were exclusively present in patients with MCC, but not in healthy donors. We further demonstrate both the processing and presentation of the oncoprotein-derived epitopes, as well as the lytic activity of oncoprotein-specific T cells toward MHC-matched MCC cells. Demonstrating the presence of oncoprotein-specific T cells among tumor-infiltrating lymphocytes further substantiated the relevance of the identified epitopes. Conclusion: These T-cell epitopes represent ideal targets for antigen-specific immune therapy of MCC, and enable tracking and characterization of MCPyV-specific immune responses. Clin Cancer Res; 20(7); 1768–78. ©2014 AACR.

In-chip fabrication of free-form 3D constructs for directed cell migration analysis

Free-form constructs with three-dimensional (3D) microporosity were fabricated by two-photon polymerization inside the closed microchannel of an injection-molded, commercially available polymer chip for analysis of directed cell migration. Acrylate constructs were produced as woodpile topologies with a range of pore sizes from 5 × 5 μm to 15 × 15 μm and prefilled with fibrillar collagen. Dendritic cells seeded into the polymer chip in a concentration gradient of the chemoattractant CCL21 efficiently negotiated the microporous maze structure for pore sizes of 8 × 8 μm or larger. The cells migrating through smaller pore sizes made significantly more turns than those through larger pores. The introduction of additional defined barriers in the microporous structure resulted in dendritic cells making more turns while still being able to follow the chemoattractant concentration gradient.

High immunogenic potential of p53 mRNA-transfected dendritic cells in patients with primary breast cancer.

As pre-existent immunity might be a reflection of an emerging anticancer response, the demonstration of spontaneous T-cell responses against tumor associated antigens (TAAs) in cancer patients may be beneficial before clinical development of dendritic cell (DC)-based cancer vaccines, because it will help to identify likely responders to TAAs among patients who qualify and may benefit from this form of immune therapy. This study aimed to determine pre-existent T-cell reactivity against the tumor suppressor protein p53 in breast cancer patients (BCP) at the time point of primary diagnosis. After a short-term stimulation with autologous wt p53 mRNA-transfected DCs, IFN-γ enzyme-linked immunosorbent spot (ELISPOT) analysis revealed p53-reactive T cells in the peripheral blood of more than 40% (15 of 36) of the tested patients. Both CD4+ and CD8+ p53-specific T cells secreted IFN-γ after stimulation with p53-transfected DCs. Interestingly, more than 72% (13 of 18) of patients with high p53 (p53high) expression in tumors were able to mount a p53-specific IFN-γ T-cell response, in contrast to only 10% (1 of 10) of healthy donors and 11% (2 of 18) of patients with low or absent p53 (p53low) expression in tumors. Furthermore, significantly higher secretion of IL-2 was detected in peripheral blood mononuclear cells after stimulation with p53-transfected DCs from patients with p53high tumor expression compared to patients with p53low tumor expression, whereas secretion of IL-10 was predominant in the latter group. The high frequency of spontaneous wt p53-reactive T cells detected in the peripheral blood of primary BCP with accumulation of p53 in tumor provides a rationale to consider DCs transfected with mRNA encoding wt p53 for clinical investigation in these patients.

Immunobiological Effects of Glucosamine In Vitro

Glucosamine (GlcN) and N‐acetyl‐d‐glucosamine (GlcNAc) were assayed in vitro for their effects on proliferation, cytotoxicity and cytokine secretion in primary and secondary mixed lymphocyte cultures (MLCs). In addition, we studied the effect of GlcN and GlcNAc on the proliferation of purified CD4+ T cells exposed to immobilized anti‐CD3 antibody. The present data show that GlcN, but not GlcNAc, inhibits CD4+ T‐cell proliferation, the generation of alloreactive cytotoxic T lymphocytes (CTLs) and the secretion of interferon‐γ (IFN‐γ) and interleukin‐5 (IL‐5) in primary MLC. In secondary T helper‐2 (Th2)‐polarized MLC, GlcN, but not GlcNAc, inhibits IL‐4 and IL‐5 secretion, whereas no effect was found on IFN‐γ secretion in Th1‐polarized MLC. Dendritic cells treated with GlcN showed a 75–80% decreased capacity for antigen cross‐presentation and allostimulation. In cellular bioassays, GlcN was shown to inhibit the stimulatory activity of IL‐4 and IL‐2, as well as the cytotoxic activity of tumour necrosis factor‐α (TNF‐α). In conclusion, GlcN suppresses unprimed T‐cell responses by interfering with antigen‐presenting cell functions and by a direct inhibitory effect on T‐cell proliferation. In addition, GlcN inhibits the secretion of cytokines in antigen‐stimulated unprimed T cells and primed Th2‐polarized cells.

Peptide-loaded dendritic cells prime and activate MHC-class I-restricted T cells more efficiently than protein-loaded cross-presenting DC.

Undifferentiated and differentiated dendritic cells (uDC and dDC, respectively), derived from the bone marrow, were studied in vitro and in vivo. Ovalbumin (OVA) and two OVA-derived peptides binding to H-2K(b) and I-A(b), respectively, were used. Two IL-2 secreting T cell hybridomas specific for the OVA-derived epitopes were used in the in vitro read-out. The ability to cross-present the H-2K(b) binding OVA(257-264)-peptide (SIINFEKL) was restricted to dDC, which express CD11c(+), CD86(+), and MHC-II(+). In vitro, the antigenicity of SIINFEKL-loaded DC declined at a slower rate than that of OVA-pulsed DC. Moreover, SIINFEKL-loaded DC were up to 50 times more efficient than DC-pulsed with OVA-protein for generation of an H-2K(b)-restricted response. Immunization of mice with SIINFEKL-loaded DC resulted in a much stronger H-2K(b)-restricted response than immunization with OVA-pulsed DC. These data might have important implications for the choice of antigen source in the design of DC-based vaccines.

Cellular Based Cancer Vaccines: Type 1 Polarization of Dendritic Cells

Cancer vaccines designed to re-calibrate the existing host-tumour interaction, tipping the balance from tumor acceptance towards tumor control holds huge potential to complement traditional cancer therapies. In general, limited success has been achieved with vaccines composed of tumor-associated antigens introduced to dendritic cells (DCs) generated in vitro. This may in part result from suboptimal maturation of DCs leading to insufficient production of IL-12, a key driver of cellular immunity. Therefore, tremendous efforts have been put into the design of maturation cocktails that are able to induce IL-12 secreting type 1 polarized DCs mimicing pathogen-derived molecular activation of DCs. Correct timing and potential synergisms of clinical-grade toll-like receptor ligands, interferons (IFN) and CD40L enhance IL-12 production in DCs. However, cytokine exhaustion, predominant expression of tolerogenic molecules and activation-induced dendritic cell death should be avoided. Thus, compounds such as IFN-γ may initially induce immunity but later on tolerance. Maturation with PGE(2) obviously promotes migration via expression of CCR7 but on the down side PGE(2) limits the production of IL-12 especially following encounter with CD40L-expressing cells and furthermore, PGE(2) imprints DCs for preferential interaction with tolerogenic T cells. In addition, type 1 polarized DCs matured without PGE(2) also seem to be capable of migrating in vivo, although concomitant production of CCL19 seems to transiently affect in vitro migration via autocrine receptor-mediated endocytosis of CCR7. In the current review, we discuss optimal design of DC maturation focused on pre-clinical as well as clinical results from standard and polarized dendritic cell based cancer vaccines.

Simplified protocol for clinical-grade tumor-infiltrating lymphocyte manufacturing with use of the Wave bioreactor

BACKGROUND AIMS The high level of complexity of current Good Manufacturing Practice-compliant methods of manufacturing hampers rapid and broad application of treatment with tumor-infiltrating lymphocytes (TILs). METHODS To ensure higher applicability of TIL production to laboratory routine, a practical and simple protocol of TIL manufacturing with the use of a closed-system bioreactor was developed and implemented at our institution. RESULTS This protocol enabled significant work load reduction during the most labor-intense step of TIL expansion, and allowed generation of high-quality TIL products, which mediated clinical regression in patients with metastatic melanoma. CONCLUSIONS Implementation of simplified methods of TIL expansion will speed up dissemination of TIL methods worldwide and will increase patient access to this highly effective treatment.