PEOPLE (NCT03447678), a first-line phase II pembrolizumab trial, in negative and low PD-L1 advanced NSCLC: clinical outcomes and association with circulating immune biomarkers

BACKGROUND

The PEOPLE trial aimed to identify new immune biomarkers in negative and low programmed death-ligand 1 (PD-L1) (0%-49%) advanced non-small-cell lung cancer (aNSCLC) patients treated with first-line pembrolizumab. Here we report the main outcomes and the circulating immune biomarkers analysis.

PATIENTS AND METHODS

The primary endpoint of this phase II trial was the identification of immune biomarkers associated with progression-free survival (PFS). Overall survival (OS), objective response rate (ORR), disease control rate (DCR), duration of response (DoR) and safety were secondary endpoints. Absolute cell counts for 36 subsets belonging to innate and adaptive immunity were determined by multiparametric flow cytometry in peripheral blood at baseline and at first radiologic evaluation. An orthoblique principal components-based clustering approach and multivariable Cox regression model adjusted for clinical variables were used to analyze immune variables and their correlation with clinical endpoints.

RESULTS

From May 2018 to October 2020, 65 patients were enrolled. After a median follow-up of 26.4 months, the median PFS was 2.9 months [95% confidence interval (CI) 1.8-5.6 months] and median OS was 12.1 months (95% CI 8.7-17.1 months). The ORR was 21.5%, DCR was 47.7% and median DoR was 14.5 months (95% CI 6.4-24.9 months). Drug-related grade 3-4 adverse events were 9.2%. Higher T cell and natural killer (NK) cell count at baseline and at the first radiologic evaluation were associated with improved PFS, DCR and OS. On the contrary, higher myeloid cell count at baseline or at the first radiologic evaluation was significantly associated with worse OS and DCR.

CONCLUSIONS

Circulating immune biomarkers can contribute to predict outcomes in negative and low PD-L1 aNSCLC patients treated with first-line single-agent pembrolizumab.

The Role of Cytokines in the Modulation of Cell Surface Antigens of Human Melanoma

A number of different cytokines, including IL-1α. and ß, IL-2, IL-3, IL-4, IL-6, IL-7, IL-8, IFN-α, -ß and γ, TNF-α -ß, and TGF-ß1, can modulate the expression of distinct cell surface antigens of normal and neoplastic cells. Both induction/increase of expression and reduction of expression can be achieved depending on the antigen and on the cytokine. Antigens subjected to the modulating activity of cytokines include distinct families of cell surface structures such as the molecules coded by the major histocompatibility complex (MHC), the superfamily of adhesion receptors that regulate cell-cell and cell-matrix interaction, receptors for cytokines and growth factors and tumor-associated antigens. The modulating activity of cytokines is a consequence of their influence on gene expression, protein synthesis, membrane expression and shedding of antigens from the cell surface. The changes of phenotype due to the action of cytokines can influence the signalling pathways dependent on the expression and function of cell surf ace structures. Therefore, the antigen modulating activity of cytokines can thoroughly affect the biological behavior of normal and neoplastic cells. As described here, most of the modulating effects of cytokines on different cell surface structures and the functional consequences of antigenic modulation can be verified in human malignant melanoma cells.

Synergistic anti-tumor activity and inhibition of angiogenesis by cotargeting of oncogenic and death receptor pathways in human melanoma

Improving treatment of advanced melanoma may require the development of effective strategies to overcome resistance to different anti-tumor agents and to counteract relevant pro-tumoral mechanisms in the microenvironment. Here we provide preclinical evidence that these goals can be achieved in most melanomas, by co-targeting of oncogenic and death receptor pathways, and independently of their BRAF, NRAS, p53 and PTEN status. In 49 melanoma cell lines, we found independent susceptibility profiles for response to the MEK1/2 inhibitor AZD6244, the PI3K/mTOR inhibitor BEZ235 and the death receptor ligand TRAIL, supporting the rationale for their association. Drug interaction analysis indicated that a strong synergistic anti-tumor activity could be achieved by the three agents and the AZD6244–TRAIL association on 20/21 melanomas, including cell lines resistant to the inhibitors or to TRAIL. Mechanistically, synergy was explained by enhanced induction of caspase-dependent apoptosis, mitochondrial depolarization and modulation of key regulators of extrinsic and intrinsic cell death pathways, including c-FLIP, BIM, BAX, clusterin, Mcl-1 and several IAP family members. Moreover, silencing experiments confirmed the central role of Apollon downmodulation in promoting the apoptotic response of melanoma cells to the combinatorial treatments. In SCID mice, the AZD6244–TRAIL association induced significant growth inhibition of a tumor resistant to TRAIL and poorly responsive to AZD6244, with no detectable adverse events on body weight and tissue histology. Reduction in tumor volume was associated not only with promotion of tumor apoptosis but also with suppression of the pro-angiogenic molecules HIF1α, VEGFα, IL-8 and TGFβ1 and with inhibition of tumor angiogenesis. These results suggest that synergistic co-targeting of oncogenic and death receptor pathways can not only overcome melanoma resistance to different anti-tumor agents in vitro but can also promote pro-apoptotic effects and inhibition of tumor angiogenesis in vivo.

Immunization of indolent non-Hodgkin’s lymphoma patients with autologous monocyte-derived dendritic cells loaded with heat shocked and killed autologous tumor cells: A phase I study

3006

Background: To evaluate the safety and tolerability of vaccination with DCs loaded with killed tumor cells, 18 patients with measurable relapse/refractory follicular (12) and lymphoplasmocytoid (6) lymphoma have been enrolled in a phase I study. Methods: Each patient received at 2-weekly intervals 4 SC injections of 50x10e6 tumor-loaded DCs. Immature DCs were generated by 5-days culture of autologous monocytes in the presence of IL-4 and GM-CSF. Autologous CD19+ tumor cells, harvested from lymph nodes (12) and/or peripheral blood (6), were heat shocked and then irradiated by UVC. DCs were loaded for 48 hrs with killed tumor cells and then were cultured for 12 hrs in the presence of TNF-a. Median prior number of treatment regimens was 2 (range 1–5) comprising 4 patients treated with high-dose chemotherapy. The vaccination was started at least 6-months after the last chemotherapy treatment. Results: All patients were evaluable for toxicity and for efficacy with a median follow-up of 30.5 months (range 18–45 months). Overall, vaccinations were well tolerated and no autoimmune reactions were observed. Mild erythema in the site of injection developed in the majority of patients (12/18), but only in 2 cases induration and extended erythema was observed. Six of 18 patients had objective responses. Three patients had partial responses (PR). One is still in PR and the others have a PR lasting 7 and 15 months, respectively. Three patients had complete remission (CR) and are are still in CR with a mean CR duration of 17 months. The remaining 12 patients had stable disease (8) or progressive disease (4). In the patients in PR, a significant increase of anti autologous tumor-specific T cells, evaluated by ELISPOT assay for IFN-γ, was observed in the post-vaccination lymph nodes, compared to the tissue sample taken before vaccination. In addition, in the responding patients a significant reduction in peripheral blood of FoxP3+ regulatory T cells was observed. Conclusion: The injection of DCs loaded with killed tumor cells is a well-tolerated procedure achieving clinical and immunological responses also in the presence of significant tumor burden.

No significant financial relationships to disclose.

Mutually exclusive NRASQ61R and BRAFV600E mutations at the single-cell level in the same human melanoma

Activating BRAF or NRAS mutations have been found in 80% of human sporadic melanomas, but only one of these genetic alterations could be detected in each tumour. This suggests that BRAF and NRAS 'double mutants' may not provide advantage for tumour growth, or may even be selected against during tumorigenesis. However, by applying mutant-allele-specific-amplification-PCR method to short-term melanoma lines, one out of 14 tumours was found to harbour both BRAFV600E and the activating NRASQ61R mutations. On the other hand, analysis of 21 melanoma clones isolated by growth in soft agar from this tumour indicated that 16/21 clones harboured a BRAFV600E, but were wild-type for NRAS, whereas the remaining had the opposite genotype (NRASQ61R/wild-type BRAF). When compared to BRAFV600E clones, NRASQ61R clones displayed reduced growth in soft agar, but higher proliferative ability in vitro in liquid medium and even in vivo after grafting into SCID/SCID mice. These data suggest that NRAS and BRAF activating mutations can coexist in the same melanoma, but are mutually exclusive at the single-cell level. Moreover, the presence of NRASQ61R or BRAFV600E is associated with distinct in vitro and in vivo growth properties of neoplastic cells.

Phases of apoptosis of melanoma cells, but not of normal melanocytes, differently affect maturation of myeloid dendritic cells

In this study, we investigated whether maturation of monocyte-derived myeloid dendritic cells (DCs) is differentially affected by the uptake of dying human melanoma cells in distinct phases of apoptosis. Maturation of monocyte-derived DCs, as documented by phenotype analysis and T-cell immunostimulatory activity, was inhibited by phagocytosis of dying melanoma cells containing a large fraction of cells in early apoptosis (Annexin-V+ and propidium iodide-) but promoted by the same tumors when in late apoptosis/secondary necrosis (Annexin-V+ and propidium iodide+) or when dying by primary necrosis. These opposite effects on DC maturation were observed after the uptake of early or late apoptotic cells from most vertical growth phase primary tumors and all metastases but not after the uptake of dying cells from a radial growth phase primary tumor or normal adult melanocytes. Inhibition of DC maturation by early apoptotic melanoma cells correlated with expression of interleukin-10 in neoplastic cells and was prevented by preincubating the tumor cells with a neutralizing antibody to interleukin-10 before tumor uptake by DCs. Cross-presentation of the melanoma-associated antigen gp100(209-217) to peptide-specific CTLs by HLA-A*0201+ DCs was achieved 48-72 h after phagocytosis of HLA-A*0201- melanoma cells in apoptosis, or primary necrosis, but only when tumor necrosis factor-alpha was added to DCs 4 h after the initiation of tumor phagocytosis. These results suggest that phases of apoptosis and neoplastic transformation affect maturation of myeloid DCs that take up dying cells of the melanocyte lineage. However, neoplastic cells in late apoptosis, or even in primary necrosis, induce only a partial DC differentiation not sufficient to achieve cross-presentation of tumor antigens to CTLs unless further DC maturation is promoted by additional signals. These results suggest a novel mechanism of tumor escape that may prevent the development of antitumor immunity through the maturation block induced in DCs by neoplastic cells in the early phase of apoptosis.

Large-scale feasibility of gene transduction into human CD34+ cell-derived dendritic cells by adenoviral/polycation complex

With a view to using multiple injections of anti-cancer dendritic cell (DC)-based vaccines, we evaluated the feasibility of the adenoviral transduction of large amounts of human CD34+ cell-derived DCs, and analysed the persistence of the transgene expression and the integrity of DC functional activity after the transduction/cryopreservation procedures. Mature DCs generated from highly enriched human CD34+ cells were transduced by a recombinant adenovirus (rAd-MFG) that carried a modified, membrane-exposed, alkaline phosphatase (AP) sequence as the reporter gene. Cationic lipids such as LipofectAmine or poly-L-lysine were mixed with the viral particles before the transduction of the target cells. The highest transduction efficiency was obtained at a multiplicity of infection (MOI) rate of 500 (AP + DCs: 50 +/- 2%, viability =95%) under both small- and large-scale conditions. The addition of poly-L-lysine or LipofectAmine increased the percentage of transduced cells at an MOI of 500 (CD1a+/AP+ cells = 85 +/- 3% and 80 +/- 2% respectively). Polycations made it possible to reduce the amounts of viral particles, with high efficiency of transduction being achieved at a MOI of 100 with 10 microg/ml poly-L-lysine (CD1a+/AP+: 68 +/- 9%) or 30 microg/ml LipofectAmine (CD1a+/AP+: 60 +/- 7%). Evaluation of the immunophenotype of the transduced DCs showed that the lack of a DC subpopulation was more susceptible to adenoviral transduction. Cryopreservation of transduced DCs did not modify the viability or percentage of AP+ cells that maintain antigen-presenting cell (APC) functions. These findings indicate the efficacy of this method for the transduction of large amounts of CD34+ cell-derived DCs using small quantities of adenoviral vector mixed with polycations. Cryopreservation of transduced DCs did not damage their viability or APC functions, thus making it possible to plan multiple injections of engineered DC-based vaccines.

The alpha 3 beta 1 integrin is associated with mammary carcinoma cell metastasis, invasion, and gelatinase B (MMP-9) activity

The alpha 3 beta 1 integrin is elevated in several types of metastatic tumor and has been associated with increased migration and invasion. Our analysis of a series of mammary carcinomas of different histotypes and their corresponding metastases demonstrated significantly increased expression of alpha 3 beta 1 in the tumor metastases. We therefore studied alpha 3 beta 1 expression of several human breast carcinoma cell lines and its association with the invasive phenotype. The MDA-MB-231 cell line expressed high levels of the beta1, alpha 2, alpha 3, alpha 5, and alpha 6 integrin subunits along with moderate levels of the alpha v beta 3 integrin. This line was highly migratory and the most invasive using a chemo-invasion assay. In contrast, the other lines tested, MDA-MB-145, MCF-7, and SK-BR-3, showed lower migratory and invasive activity and reduced alpha 3 integrin subunit expression. Metalloproteases capable of degrading collagen IV are necessary for the invasive process. RT-PCR showed that MDA-MB-231 cells expressed MMP-9, but not MMP-2, gelatinase/collagenase IV. Gelatin zymography demonstrated that invading MDA-MB-231 cells released high levels of MMP-9 gelatinase activity. A direct role for this gelatinase in MDA-MB-231 cell invasion was confirmed by inhibition of invasion using the metalloprotease inhibitor Batimastat. Treatment of MDA-MB-231 cells with a function-blocking anti-alpha 3 antibody strongly inhibited migration and invasion. This correlated with a marked reduction in MMP-9 activity produced by MDA-MB-231 cells, suggesting a role for alpha 3 beta 1 ligand binding in cell signaling and regulation of extracellular matrix degradation.

Peripheral burst of tumor-specific cytotoxic T lymphocytes and infiltration of metastatic lesions by memory CD8+ T cells in melanoma patients receiving interleukin 12

Systemic effects on T-cell-mediated antitumor immunity, on expression of T-cell adhesion/homing receptors, and on the promotion of T-cell infiltration of neoplastic tissue may represent key steps for the efficacy of immunological therapies of cancer. In this study, we investigated whether these processes can be promoted by s.c. administration of low-dose (0.5 microg/kg) recombinant human interleukin-12 (rHuIL-12) to metastatic melanoma patients. A striking burst of HLA-restricted CTL precursors (CTLp) directed to autologous tumor was documented in peripheral blood by a high-efficiency limiting dilution analysis technique within a few days after rHuIL-12 injection. A similar burst in peripheral CTLp frequency was observed even when looking at response to a single tumor-derived peptide, as documented by an increase in Melan-A/Mart-1(27-35)-specific CTLp in two HLA-A*0201+ patients by limiting dilution analysis and by staining peripheral blood lymphocytes (PBLs) with HLA-A*0201-melanoma antigen-A/melanoma antigen recognized by T cells (Melan-A/Mart)-1 tetrameric complexes. The CTLp burst was associated, in PBLs, with enhanced expression of T-cell adhesion/homing receptors CD11a/CD18, CD49d, CD44, and with increased proportion of cutaneous lymphocyte antigen (CLA)-positive T cells. This was matched by a marked increase, in serum, of soluble forms of the endothelial cell adhesion molecules E-selectin, vascular cell adhesion molecules (VCAM)-1 and intercellular adhesion molecules (ICAM)-1. Infiltration of neoplastic tissue by CDS+ T cells with a memory and cytolytic phenotype was found by immunohistochemistry in eight of eight posttreatment metastatic lesions but not in five of five pretreatment metastatic lesions from three patients. Increased tumor necrosis and/or fibrosis were also found in several posttherapy lesions of two of three patients in comparison with pretherapy metastases. These results provide the first evidence that rHuIL-12 can boost the frequency of circulating antitumor CTLp in tumor patients, enhances expression of ligand receptor pairs contributing to the lymphocyte function-associated antigen-1/ICAM-1, very late antigen-4/VCAM-1, and CLA/E-selectin adhesion pathways, and promotes infiltration of neoplastic lesions by CD8+ memory T cells in a clinical setting.

An expanded peripheral T cell population to a cytotoxic T lymphocyte (CTL)-defined, melanocyte-specific antigen in metastatic melanoma patients impacts on generation of peptide-specific CTLs but does not overcome tumor escape from immune surveillance in metastatic lesions

It is not known if immune response to T cell-defined human histocompatibility leukocyte antigen (HLA) class I-restricted melanoma antigens leads to an expanded peripheral pool of T cells in all patients, affects cytotoxic T lymphocyte (CTL) generation, and correlates with anti-tumor response in metastatic lesions. To this end, a limiting dilution analysis technique was developed that allowed us to evaluate the same frequency of peptide-specific T cells as by staining T cells with HLA-peptide tetrameric complexes. In four out of nine patients, Melan-A/Mart-1(27-35)-specific CTL precursors (CTLp) were >/=1/2,000 peripheral blood lymphocytes and found mostly or only in the CD45RO(+) memory T cell subset. In the remaining five patients, a low (<1/40,000) peptide-specific CTLp frequency was measured, and the precursors were only in the CD45RA(+) naive T cell subset. Evaluation of CTL effector frequency after bulk culture indicated that peptide-specific CTLs could be activated in all patients by using professional antigen-presenting cells as dendritic cells, but CTLp frequency determined the kinetics of generation of specificity and the final number of effectors as evaluated by both limiting dilution analysis and staining with HLA-A*0201-Melan-A/Mart-1 tetrameric complexes. Immunohistochemical analysis of 26 neoplastic lesions from the nine patients indicated absence of tumor regression in most instances, even in patients with an expanded peripheral T cell pool to Melan-A/Mart-1 and whose neoplastic lesions contained a high frequency of tetramer-positive Melan-A/Mart-1-specific T cells. Furthermore, frequent lack of a "brisk" or "nonbrisk" CD3(+)CD8(+) T cell infiltrate or reduced/absent Melan-A/Mart-1 expression in several lesions and lack of HLA class I antigens were found in some instances. Thus, expansion of peripheral immune repertoire to Melan-A/Mart-1 takes place in some metastatic patients and leads to enhanced CTL induction after antigen-presenting cell-mediated selection, but, in most metastatic lesions, it does not overcome tumor escape from immune surveillance.

Human dendritic cells: natural adjuvants in antitumor immunotherapy

Although T-cell-defined tumor antigens have recently been identified in several tumors, human neoplastic cells are considered to be poorly immunogenic. The development of clinical approaches to the immunotherapy of human tumors thus requires the identification of effective adjuvants. Dendritic cells (DC) are a specialized system of antigen-presenting cells (APC) that could be utilized as natural adjuvants to elicit antitumor immune responses. In an attempt to overcome the problem of the low frequency of mature DC in peripheral blood, several methods have been applied for the ex vivo generation of human DC by culturing mobilized CD34+ cells or monocytes with combinations of cytokines. As shown in murine models as well as in the human system, after loading with peptides or tumor lysates or infection with recombinant viral vectors, DC expressing tumor antigens are able to elicit specific antitumor T cells and to mediate tumor regression. These initial results suggest that this new approach may lead to effective antitumor responses even in heavily pretreated patients bearing advanced cancers, but further clinical trials are required to validate the efficacy of vaccination with tumor-antigen-loaded DC.

Gene transfer into human dendritic antigen-presenting cells by vaccinia virus and adenovirus vectors

In a search for means to deliver exogenous gene(s) into human dendritic cells (DCs) from the perspective of tumor-specific vaccination, we have evaluated two recombinant viruses, both of which carry a reporter gene which is namely a modified vaccinia virus Ankara (MVA) and an adenovirus, as possible expression vectors. The recombinant MVA-P11 LZ vector carries the Escherichia coli lacZ gene coding for the enzyme beta-galactosidase, and the recombinant Ad-MFG-AP vector carries a modified membrane-exposed alkaline phosphatase (AP) gene. DCs were generated ex vivo in the presence of tumor necrosis factor-alpha, granulocyte macrophage colony-stimulating factor, stem cell factor, and flk-2/flt-3 ligand taken from CD34+ hematopoietic progenitors that were mobilized into the peripheral blood of cancer patients treated with high-dose cyclophosphamide and filgrastim. The target cells used for gene delivery were either CD34+ cells that had been subsequently induced to differentiate into mature DCs or DCs transduced after ex vivo generation from CD34+ cells. The results showed that: (a) infection of CD34+ cell derived-DCs (mature DCs) with either viral vector resulted in the efficient synthesis of recombinant protein, and (b) CD34+ cells were permissive for the expression of the recombinant reporter gene after infection with Ad-MFG-AP but not after infection with MVA-P11 LZ. In conclusion, these results suggest that vaccinia and adenovirus vectors are candidate to act as vehicles in genetically engineering human DCs.

Monocyte-derived dendritic cells and monocytes migrate to HIV-Tat RGD and basic peptides

OBJECTIVE AND DESIGN

Extracellular Tat released from HIV-1-infected cells is a mitogenic and motogenic factor for endothelial and Kaposi's sarcoma (KS)-derived cells and is angiogenic in vivo. Here we show for the first time that Tat induces migration of human dendritic cells in a concentration-dependent manner and that the Arg-Gly-Asp (RGD) and basic Tat peptides contribute to dendritic and monocyte cell migration. In vivo, Tat stimulates invasion of macrophages into a matrigel sponge.

METHODS

Monocyte and dendritic cell chemotaxis was assessed using the Boyden chamber assay.

RESULTS

Tat induced migration of monocyte-derived dendritic cells at the same levels as the N-formyl-Met-Leu-Phe peptide, and of monocytes at levels comparable to RANTES. Peptide mapping of the chemotactic activity of Tat showed that the RGD domain, which has been shown to support integrin-mediated cell migration, and the basic domain which binds and activates the tyrosine kinase receptor KDR on endothelial cells, both had activity. Antibody-blocking experiments indicate that responses to the RGD domain was inhibited by beta1 and alpha vbeta3 integrin blocking antibodies. Combination of the Tat RGD and basic peptides did not show additive effects; however, Tat co-operated with macrophage-chemotactic protein or RANTES in inducing monocyte migration.

CONCLUSIONS

Our results show that Tat can act as a chemoattractant for dendritic cells, and that both the RGD and basic domains are involved in this response. These same domains attract monocytes. The alpha vbeta3 and beta1 integrins are equally involved in Tat-induced monocyte migration, while the alpha vbeta3 integrin largely mediates the dendritic cell response to Tat.

Pilot study of subcutaneous recombinant human interleukin 12 in metastatic melanoma

The aim of this study was to evaluate the safety profile of s.c. administered recombinant human interleukin 12 (rHuIL-12). Pharmacokinetics and pharmacodynamics of rHuIL-12 and any evidence of antitumor effect were also considered. Ten pretreated patients with progressive metastatic melanoma were enrolled in this pilot study. Patients received a fixed dose of rHuIL-12 (0.5 microgram/kg) for two identical 28-day cycles, with injections given on days 1, 8, and 15 of each cycle. In case of any evidence of response or disease stabilization, the treatment was continued for two further 28-day cycles. Toxicity mainly consisted of a flu-like syndrome. Transient increases in transaminasemia (6 of 10 patients) and triglyceridemia (8 of 10 patients) were observed. Peak serum IL-12 levels were reached 8-12 h after the first injection in all patients; no serum IL-12 was detectable in 6 of 9 evaluable patients after the last injection of the second cycle. No antibody response to rHuIL-12 could be detected in any of the patients. A marked, transient reduction in circulating CD8+ and CD16+ lymphocytes and neutrophils was observed after the first administration and high levels of serum IFN-gamma and IL-10 were detected in all patients within 24-48 h. Tumor shrinkage, not reaching partial or complete remission, involved the regression of s.c. nodules (2 of 3 patients), superficial adenopathies (1 of 3 patients), and hepatic metastases (1 of 3 patients); regressions were detected after the first cycle of treatment and were maintained in spite of progression at different sites. s.c. rHuIL-12 treatment was well tolerated and had marked effects on immune parameters and potential antitumor activity.

Autologous dendritic cells derived from CD34+ progenitors and from monocytes are not functionally equivalent antigen-presenting cells in the induction of melan-A/Mart-1(27-35)-specific CTLs from peripheral blood lymphocytes of melanoma patients with low frequency of CTL precursors

Peptide presentation by autologous dendritic cells (DCs) is a new tool to activate tumor antigen-specific T cells in melanoma patients. However, it is not known whether autologous DCs, differentiated by two of the most efficient protocols (from CD34+ progenitors or from monocytes), are equally effective as professional antigen-presenting cells (APCs) when the patients have a low frequency of peptide-specific precursors. To this end, a limiting dilution assay was applied to evaluate the frequency of antigen-specific CTL precursors (CTLps) in peripheral blood of HLA-A*0201+ melanoma patients. Then, from two melanoma patients showing low frequency of CTLps to melanoma antigen-A/melanoma antigen recognized by T cell (Melan-A/Mart-1)(27-35) peptide, autologous DCs were differentiated from granulocyte colony-stimulating factor-mobilized CD34+ progenitors or from monocytes. CD34+- and monocyte-derived DCs were characterized by a similar proportion of CD1a+ cells expressing HLA class II antigens and CD54, CD80, and CD86 molecules. Both types of DC presented Melan-A/Mart-1(27-35) and tyrosinase(369-377) peptides to melanoma-specific CTL clones and were equally effective as peptide-pulsed APCs in the activation of influenza A matrix(58-66)-specific CTLs from high-frequency precursors (1294/10(6) and 1789/10(6) lymphocytes in the two patients). However, efficient activation of Melan-A/Mart-1(27-35)-specific CTLs from low-frequency precursors (158/10(6) and 77/10(6) lymphocytes) of the two patients was markedly dependent on the use of peptide-loaded CD34+-derived DCs. These results suggest that CD34+- and monocyte-derived DCs are not functionally equivalent APCs for the activation of low-frequency peptide-specific CTLps.

Differential patterns of HOX gene expression are associated with specific integrin and ICAM profiles in clonal populations isolated from a single human melanoma metastasis

Homeobox-containing genes comprise a gene family coding for transcription factors involved in normal development. Class I human homeobox (HOX) genes display a peculiar chromosomal organization, perhaps directly related to their function. Aberrant expression of homeobox genes has been associated with both morphological abnormalities and oncogenesis. We have reported that HOX gene expression is (i) specific for normal adult human organs (kidney, colon, lung) and (ii) altered in cancer specimens according to their histological type and stage of tumor progression. Here, we have investigated whether patterns of HOX gene expression are associated with tumor heterogeneity by analyzing the expression of the entire panel of 38 HOX genes in clones isolated from a single human metastatic melanoma call line (Me 665/2). The differential expression of a block of genes located at the 5' end of the HOX C locus allows melanoma clones to be classified into 2 major groups. The 2 patterns of HOX gene expression are inversely associated with 2 distinct surface phenotypes for integrins (VLA-2, VLA-5 and VLA-6) and the adhesion molecule ICAM-1. The genes of the HOX C locus are silent in the clones with high levels of integrins VLA-2, VLA-5 and VLA-6 and of the adhesion molecule ICAM-1 but actively expressed in the clones with low levels of ICAM-1 and lacking VLA-2, VLA-5 and VLA-6. Our results indicate that HOX gene expression reflects the intra-tumor heterogeneity of melanoma clones and suggest that the expression of surface molecules involved in cell-cell and cell-matrix interactions may be related to the patterns of HOX gene expression.

Interaction with fibronectin regulates cytokine gene expression in human melanoma cells

Our study was aimed at investigating whether interaction of human melanoma cells with the extracellular matrix (ECM) protein fibronectin (FN) could regulate lymphokine gene expression. Serum-deprived cells (quiescent condition) of a metastatic melanoma cloned line were cultured either on uncoated or on FN- or BSA-coated surfaces. By means of reverse transcriptase- polymerase chain reaction (RT-PCR), we analyzed mRNA expression of 4 cytokines interleukin (IL)-1alpha, IL, 1beta, IL-6 and IL-8-and 9 growth factors-endothelial cell growth factor (ECGF), basic fibroblast growth factor (bFGF), fibroblast growth factor (FGF)-5, HST, keratinocyte growth factor (KGF), transforming growth factor (TGF)-alpha TGF-beta1, TGF-beta2 and TGF-beta3. When cultured on FN, melanoma cells expressed IL-1beta and IL-6 transcripts in addition to IL-1beta, IL-8, ECGF, TGF-beta1, TGF-beta2 and TGF-beta3, already present in quiescent cells. Amplification parameters to achieve semi-quantitative RT-PCR were then determined for each detectable factor, thus allowing us to measure a selective enhancement of mRNA levels for IL-1alpha, IL-6, IL-8 and TGF-beta2 upon interaction with FN by quiescent melanoma cells. This augmented expression was inhibited by an anti-integrin beta1 chain monoclonal antibody (MAb). Moreover, the amounts of IL-6, IL-8 and IL-beta produced in the supernatants, as assessed by ELISA, correlated with the corresponding mRNA expression. Extension of this analysis to the other 5 human primary and metastatic melanoma lines confirmed the ability of FN to selectively up-regulate only IL-6 and IL-8 secretion. Our data indicate that FN is able to modulate expression and secretion of a defined subset of lymphokines in human melanoma.

Cytotoxic T cells directed to tumor antigens not expressed on normal melanocytes dominate HLA-A2.1-restricted immune repertoire to melanoma

To determine whether HLA-A21 restricted melanoma Ags exist that are not expressed on normal melanocytes, a panel of 478 T cell clones from six HLA-A21+ patients was selected for HLA-A2 restricted lysis of autologous tumor and then tested for differential recognition of HLA-A2.1+ melanomas and normal melanocytes. Four subsets of clones were identified in the panel of 107 HLA-A2-restricted CTL clones. CTL clones from three of the four subsets did not lyse melanocytes, but recognized fresh HLA-A2.1+ melanomas and defined three classes of epitopes, including unique Ags, common melanoma Ags, and Ags shared with neoplastic cells of different histologic origin. These CTL clones did not recognize any of the 10 peptides selected for specific association to HLA-A2.1 and derived from Melan-A/Mart-1, tyrosinase, gp100, or MAGE-3 proteins. By contrast, the fourth subset of HLA-A2.1-restricted CTl clones recognized both melanoma and melanocytes. These CTL clones were directed to a peptide from either Melan-A/Mart-1, tyronise, or gp100. By a limiting dilution assay, designed to evaluate the frequency of HLA-A2-restricted CTL precursors (CTLp) directed to melanoma but not to melanocytes, such precursors were found in the peripheral blood or tumor site of five of six HLA-A2.1+ melanoma patients, and their frequency was much higher than the frequency of CTLp recognizing both tumor cells and the melanocytes. These results suggest that in melanoma patients most of the HLA-A2.1-restricted immune repertoire to melanoma is directly to epitopes expressed in the neoplastic but not in the normal cells of the melanocyte lineage.

Cytotoxic T cells directed to tumor antigens not expressed on normal melanocytes dominate HLA-A2.1-restricted immune repertoire to melanoma

To determine whether HLA-A21 restricted melanoma Ags exist that are not expressed on normal melanocytes, a panel of 478 T cell clones from six HLA-A21+ patients was selected for HLA-A2 restricted lysis of autologous tumor and then tested for differential recognition of HLA-A2.1+ melanomas and normal melanocytes. Four subsets of clones were identified in the panel of 107 HLA-A2-restricted CTL clones. CTL clones from three of the four subsets did not lyse melanocytes, but recognized fresh HLA-A2.1+ melanomas and defined three classes of epitopes, including unique Ags, common melanoma Ags, and Ags shared with neoplastic cells of different histologic origin. These CTL clones did not recognize any of the 10 peptides selected for specific association to HLA-A2.1 and derived from Melan-A/Mart-1, tyrosinase, gp100, or MAGE-3 proteins. By contrast, the fourth subset of HLA-A2.1-restricted CTl clones recognized both melanoma and melanocytes. These CTL clones were directed to a peptide from either Melan-A/Mart-1, tyronise, or gp100. By a limiting dilution assay, designed to evaluate the frequency of HLA-A2-restricted CTL precursors (CTLp) directed to melanoma but not to melanocytes, such precursors were found in the peripheral blood or tumor site of five of six HLA-A2.1+ melanoma patients, and their frequency was much higher than the frequency of CTLp recognizing both tumor cells and the melanocytes. These results suggest that in melanoma patients most of the HLA-A2.1-restricted immune repertoire to melanoma is directly to epitopes expressed in the neoplastic but not in the normal cells of the melanocyte lineage.

Massive ex vivo generation of functional dendritic cells from mobilized CD34+ blood progenitors for anticancer therapy

We report that blood cell autografts, collected by single leukapheresis in cancer patients (n = 11) at the time of mobilization of hematopoietic progenitors into peripheral blood following anticancer therapy with high-dose cyclophosphamide (HD-CTX) plus interleukin-3 (IL-3) and granulocyte colony-stimulating factor (G-CSF/filgrastim), comprise 1.98 +/- 0.39 x 10(5)/kg (mean +/- SE) CD34+ progenitors of dendritic cells (DCs). This number corresponds to 140-fold more progenitors than in a control autograft collected in the steady state. DCs derived from mobilized CD34+ cells, morphologically and immunophenotypically undistinguishable from skin Langerhans cells and DCs from bone marrow and cord blood CD34+ cells, are shown to be powerful stimulators of allogeneic T cell proliferation in primary MLR and of autologous HLA-DR-restricted CD4+ T cell proliferation in response to presentation of xenogenic antigens. We show that the GM-CSF-plus-TNF-alpha-dependent ex vivo generation of DCs from mobilized CD34+ cells is 2.5-fold enhanced by flk-2/flt-3 ligand or c-kit ligand (stem cell factor) and five-fold enhanced by a combination of these growth factors. In addition, the optimal serum for the generation of DCs is autologous HD-CTX recovery-phase serum rather than fetal calf serum (FCS) or steady-state human serum, which are clinically inadequate and ineffective, respectively. In practice, the stimulation of CD34+ cells in a blood cell autograft (15.75 +/- 2.46 x 10(6)/kg) provided by the above four growth factors should permit ex vivo generation of approximately 40 x 10(9) DCs in an adult patient. These new findings provide advantageous tools for the large-scale generation of DCs that are potentially usable for clinical protocols of immunotherapy or vaccination in patients undergoing cancer treatment.

Mitogenic activity of laminin on human melanoma and melanocytes: different signal requirements and role of beta 1 integrins

The possible mitogenic activity of laminin (LN) on normal and neoplastic cells of the melanocyte lineage was tested by culturing growth-arrested human melanoma cells and neonatal foreskin melanocytes on LN. Serum-deprived, quiescent melanoma cells proliferated, in serum-free medium, in a dose-dependent fashion to immobilized LN as determined by [3H]thymidine incorporation, cell cycle analysis, and change in cell number. The mitogenic activity of LN on melanoma cells was not mediated through autocrine release of growth factors and was observed with primary or metastatic melanoma cells and with clones isolated from the same metastasis but only on cells expressing very late antigen (VLA)-3 and VLA-6 laminin receptors. Proliferation of melanoma cells to LN was significantly inhibited by a mAb to the beta 1 subunit of VLA integrins and by a combination of mAbs to the alpha subunits of VLA-3 and VLA-6. By contrast, LN did not act asa mitogen on human melanocytes expressing VLA-3 and VLA-6 and cultured in serum-free medium. However, a costimulatory activity of immobilized LN for proliferation of melanocytes was observed in the presence of a second signal provided by a set of different growth factors. The costimulatory activity of LN on melanocytes could be significantly inhibited by mAbs directed to the alpha and beta chain of VLA-6 but not to VLA-3. These data suggest that LN itself, and not growth factors possibly associated with it, can exert a mitogenic activity on quiescent human melanoma cells and that a change in the signal requirements for response to LN occurs upon neoplastic transformation in the melanocyte lineage. Furthermore, beta 1 integrins are differentially involved in the response of the normal and the neoplastic cells to LN, since VLA-3 and VLA-6 cooperate in the proliferation of neoplastic cells, while VLA-6 is relevant for the response of melanocytes.

The alpha 3 beta 1 integrin is involved in melanoma cell migration and invasion

The VLA3 (alpha 3 beta 1) integrin receptor recognizes several ligands; however, the function of this integrin is still debated. Expression of VLA3 appears to be increased in malignant melanoma and correlates with the degree of dermal invasiveness. Here we have studied the role the alpha 3 integrin subunit in malignant melanoma cell migration and invasion into extracellular matrices. The 2/14 clone of the Me665/2 human melanoma cell line, which expresses high levels of VLA integrins, was highly migratory and invasive, while the low integrin expressing 2/56 clone showed limited migration and was not invasive. Antibodies to the beta 1 subunit inhibited adhesion, migration, and invasion of two different malignant melanoma cell lines, the 2/14 clone and A2058 cells, indicating a crucial role for VLA integrins in these phenomena. While anti-alpha 6 antibodies inhibited adhesion to laminin and anti-alpha 5 antibodies inhibited adhesion to fibronectin, antibodies to the alpha 3 subunit did not inhibit adhesion of these cells to laminin, fibronectin, or collagen i.v. In contrast, the P1B5 anti-alpha 3 antibodies were good inhibitors of the migration of these cells toward laminin, fibronectin, and collagen IV and also blocked invasion of these cells through a reconstituted basement membrane matrix (Matrigel). Another anti-alpha 3 antibody, F4, did not effect migration, while both the P1B5 and F4 antibodies induced cellular aggregation on Matrigel. Our data suggest a specific role for alpha 3 beta 1 in the migration and invasion of melanoma cells.

Cytotoxic T-lymphocyte clones from different patients display limited T-cell-receptor variable-region gene usage in HLA-A2-restricted recognition of the melanoma antigen Melan-A/MART-1

To determine whether T-cell-receptor (TCR) usage by T cells recognizing a defined human tumor antigen in the context of the same HLA molecule is conserved, we analyzed the TCR diversity of autologous HLA-A2-restricted cytotoxic T-lymphocyte (CTL) clones derived from five patients with metastatic melanoma and specific for the common melanoma antigen Melan-A/MART-1. These clones were first identified among HLA-A2-restricted anti-melanoma CTL clones by their ability to specifically release tumor necrosis factor in response to HLA-A2.1+ COS-7 cells expressing this tumor antigen. A PCR with variable (V)-region gene subfamily-specific primers was performed on cDNA from each clone followed by DNA sequencing. TCRAV2S1 was the predominant alpha-chain V region, being transcribed in 6 out of 9 Melan-A/MART-1-specific CTL clones obtained from the five patients. beta-chain V-region usage was also restricted, with either TCRBV14 or TCRBV7 expressed by all but one clone. In addition, a conserved TCRAV2S1/TCRBV14 combination was expressed in four CTL clones from three patients. None of these V-region genes was found in a group of four HLA-A2-restricted CTL clones recognizing different antigens (e.g., tyrosinase) on the autologous tumor. TCR joining regions were heterogeneous, although conserved structural features were observed in the complementarity-determining region 3 sequences. These results indicate that a selective repertoire of TCR genes is used in anti-melanoma responses when the response is narrowed to major histocompatibility complex-restricted antigen-specific interactions.

Involvement of the very late antigen 4 integrin on melanoma in interleukin 1-augmented experimental metastases

We have previously reported that treatment with interleukin 1 (IL-1) induced the augmentation of lung tumor colonies by a human melanoma in nude mice. Here we have investigated the involvement of the alpha 4 beta 1 integrin, the very late antigen 4 (VLA-4) in this augmentation. A375M melanoma cells expressed high levels of VLA-4 and preferentially adhered to a surface coated with vascular cell adhesion molecule 1 (VCAM-1), the ligand for VLA-4 on activated endothelial cells. This adhesion was inhibited by treating tumor cells with saturating concentrations of mAb to VLA-4. The production of lung colonies was significantly enhanced in nude mice given an injection of IL-1 before A375M melanoma cells. Immunoperoxidase staining showed that VCAM-1 could be expressed on lung vascular endothelium of mice in response to IL-1. Pretreatment of melanoma cells with a mAb to VLA-4 completely abrogated the IL-1-induced augmentation of lung colonies. Using two metastatic melanoma clones (clones 2/4 and 2/60) that expressed different levels of VLA-4, we found that only VLA-4-bearing cells adhered to a VCAM-1-coated surface and formed enhanced numbers of lung colonies in IL-1-treated nude mice. This augmentation was inhibited by pretreating the tumor cells with anti-VLA-4 mAb. These results demonstrate, in vivo, the functional involvement of VLA-4 on melanoma cells in IL-1-mediated lung colony augmentation, most probably involving the interaction of tumor cells with VCAM-1 on activated endothelial cells.

Expression of interleukin 1 alpha, interleukin 6, and tumor necrosis factor alpha genes in human melanoma clones is associated with that of mutated N-RAS oncogene

To assess whether RAS oncogenes may affect the expression of cytokines in tumor cells, the presence of interleukins (IL) 1 alpha, 1 beta, 4, 6, 7, and 8, tumor necrosis factor (TNF) alpha and interferon gamma mRNA has been analyzed by reverse transcriptase-polymerase chain reaction in 19 melanoma clones derived from the metastatic cell line 665/2 and previously characterized for RAS mutation and expression. Five of these clones and the parental cell line showed a mutation at codon 61 of N-RAS that resulted in Gln-->Arg substitution (N-RAS/61+), while in the remaining 14, only the wild-type allele for N-RAS was present (N-RAS/61-). With the exception of interferon gamma and IL-4, all the cytokines tested were expressed by the parental 665/2 cell line, whereas IL-1 alpha, IL-6, and TNF-alpha were coordinately transcribed only in the subset of the clones bearing the mutated N-RAS gene. The other cytokine genes studied (IL-1 beta, IL-4, IL-7, and IL-8) displayed a variable degree of expression, and such an heterogeneity was not correlated to the N-RAS phenotype of the clones. The association between N-RAS oncogene and IL-1 alpha, IL-6, and TNF-alpha expression was also found in a 665/2 subline (665/2/5) in which loss of mutated N-RAS genes simultaneously occurred with the loss of IL-1 alpha, IL-6, and TNF-alpha expression. Direct evidence that N-RAS oncogene could influence the pattern of cytokine expression was provided by the coordinate induction of IL-1 alpha, IL-6, and TNF-alpha messenger RNA achieved in N-RAS/61+ transfectants of the N-RAS wild-type melanoma clone 2/21. Furthermore, IL-1 alpha, IL-6, and TNF-alpha could be detected by enzyme-linked immunosorbent assay in the culture medium obtained from N-RAS/61+ melanoma clones as well as from positive transfectants, indicating that lymphokine mRNA expression triggered by the activated N-RAS oncogene lead to a secreted protein. In an N-RAS/61+ melanoma clone, by adding specific antibodies against each cytokine, it was found that soluble IL-1 alpha exerted a positive control on IL-6 mRNA and a negative one on its own expression. In addition, IL-1 alpha and IL-6 were negatively regulated by soluble IL-6 and TNF-alpha.

Multiple sub-sets of CD4+ and CD8+ cytotoxic T-cell clones directed to autologous human melanoma identified by cytokine profiles

CD4+ and CD8+ cytotoxic T-cell (CTL) clones, selected for T-cell-receptor (TcR)-dependent lysis of the autologous tumor and isolated from peripheral-blood lymphocytes (PBL) or tumor-infiltrating lymphocytes (TIL) of 3 melanoma patients, were characterized for the pattern of 13 different cytokines released by antibody- or tumor-mediated triggering. Induction or enhancement of cytokine release by anti-CD3 monoclonal antibody (MAb) led to the identification of 2 major sub-sets of CD8+ CTL clones on the basis of production of IL-4. Within the 2 groups of IL-4-producing or non-producing clones, further sub-sets could be identified on the basis of differential production of IL-1 beta, IL-2, IL-6, IL-8, IL-10, TNF-alpha, TNF beta and IFN-gamma. A similar analysis performed on a panel of CD4+ CTL clones indicated multiple patterns consistent with at least 4 major sub-sets, but further complexity was evident in each sub-set on the basis of differential production of IL-1, IL2, IL-6, IL-10 and G-CSF. The cytokine profile of CD4+ and CD8+ clones, as determined after anti-CD3 stimulation, was different from the pattern seen after co-culture with autologous tumor, since many clones released cytokines such as IL-4, IL-10, IFN-alpha and -gamma, TNF-alpha and GM-CSF after activation with only 1 of the 2 stimuli. These results indicate that CD4+ and CD8+ CTL clones reacting to human melanoma belong to a highly complex repertoire of functional subsets characterized by distinct cytokine profiles. In addition, the cytokine pattern of each T-cell sub-set can be modulated by changing the activation signals delivered to the T cell.

N-RAS mutations and susceptibility to lymphokine-activated killer (LAK) cells in human melanoma

RAS oncogene expression has been reported to affect several biological features of rodent tumours cells, including lysability by activated natural killer cells. In order to examine whether expression of mutated RAS genes in human melanoma cells alters their susceptibility to lysis by LAK cells, seven melanoma lines were assessed for the presence of Ki- and N-RAS genes bearing all possible mutations at codons 12, 13 and 61. A panel of 21 clones deriving from the metastatic lesion Me665/2, which had a Gln-->Arg substitution at codon 61 of N-RAS (N-RAS/61+), were also examined. Melanoma cells and clones were used as targets of allogeneic LAK in a 4-h 51Cr-release assay. LAK showed a higher lysis on melanoma lines and clones harbouring a mutated RAS compared with counterparts bearing no RAS mutations. In addition, LAK-mediated lysis drastically decreased on Me665/2 sublines progressively selected by exposure to LAK. This loss was paralleled by a reduction or even disappearance of N-RAS/61+ mRNA signal in Me665/2 sublines. To evaluate whether N-RAS could directly modulate LAK susceptibility to lysis, N-RAS/61+ gene was transfected in two N-RAS wild type (N-RAS/61-) 665/2 melanoma clones by a cosmid vector. In contrast to the high lysability of melanoma cells constitutively expressing the mutationally active N-RAS oncogene, N-RAS/61+ transfectants did not show a consistent high lysability by LAK, compared with some control pSV2neo transfectants.(ABSTRACT TRUNCATED AT 250 WORDS)

T cell receptor (TCR) structure of autologous melanoma-reactive cytotoxic T lymphocyte (CTL) clones: tumor-infiltrating lymphocytes overexpress in vivo the TCR beta chain sequence used by an HLA-A2-restricted and melanocyte-lineage-specific CTL clone

HLA-A2+ melanomas express common melanoma-associated antigens (Ags) recognized in vitro by autologous cytotoxic T lymphocytes (CTL). However, it is not known whether tumor Ags can drive in vivo a selective accumulation/expansion of Ag-specific, tumor-infiltrating T lymphocytes (TIL). Therefore, to evaluate this possibility, 39 CTL clones isolated from several independent mixed lymphocyte tumor cultures (MLTC) of TIL and peripheral blood lymphocytes (PBL) of an HLA-A2+ melanoma patient and selected for T cell receptor (TCR)-dependent, HLA-restricted tumor lysis, were used for analysis of TCR alpha and beta chain structure by the cDNA polymerase chain reaction (PCR) technique with variable gene-specific primers followed by sequencing. Despite absence of oligoclonality in fresh TIL and PBL, as well as in T cells of day 28 MLTC (day of cloning), sequence analysis of TCR alpha and beta chains of TIL clones revealed a dominance of a major category of melanoma-specific, HLA-A2-restricted T cells expressing a V alpha 8.2/J alpha AP511/C alpha and V beta 2.1/D beta 1/J beta 1.1/C beta 1 TCR. The same TCR was also found in 2 out of 14 PBL clones. The other PBL clones employed a V alpha 2.1 gene segment associated with either V beta 13.2, 14, or w22. Clones A81 (V alpha 2.1/J alpha IGRJ alpha 04/C alpha and V beta 14/D beta 1/J beta 1.2/C beta 1) and A21 (V alpha 8.2/J alpha AP511/C alpha and V beta 2.1/D beta 1/J beta 1.1/C beta 1), representative of the two most frequent TCR of PBL and TIL, respectively, expressed different lytic patterns, but both were HLA-A2 restricted and lysed only HLA-A2+ melanomas and normal melanocytes, thus indicating recognition of two distinct HLA-A2-associated and tissue-related Ags. Finally, by the inverse PCR technique, the specific TCR beta chain (V beta 2.1/D beta 1/J beta 1.1/C beta 1) expressed by the dominant TIL clone was found to represent 19 and 18.4% of all V beta 2 sequences expressed in the fresh tumor sample and in the purified TIL, respectively, but < 0.19% of V beta 2+ sequences expressed in PBL. These results are consistent with the hypothesis that a clonal expansion/accumulation of a melanocyte-lineage-specific and HLA-A2-restricted T cell clone occurred in vivo at the site of tumor growth.

The role of cytokines in the modulation of cell surface antigens of human melanoma

A number of different cytokines, including IL-1 alpha and beta, IL-2, IL-3, IL-4, IL-6, IL-7, IL-8, IFN-alpha, -beta and gamma, TNF-alpha -beta, and TGF-beta 1, can modulate the expression of distinct cell surface antigens of normal and neoplastic cells. Both induction/increase of expression and reduction of expression can be achieved depending on the antigen and on the cytokine. Antigens subjected to the modulating activity of cytokines include distinct families of cell surface structures such as the molecules coded by the major histocompatibility complex (MHC), the superfamily of adhesion receptors that regulate cell-cell and cell-matrix interaction, receptors for cytokines and growth factors and tumor-associated antigens. The modulating activity of cytokines is a consequence of their influence on gene expression, protein synthesis, membrane expression and shedding of antigens from the cell surface. The changes of phenotype due to the action of cytokines can influence the signalling pathways dependent on the expression and function of cell surface structures. Therefore, the antigen modulating activity of cytokines can thoroughly affect the biological behavior of normal and neoplastic cells. As described here, most of the modulating effects of cytokines on different cell surface structures and the functional consequences of antigenic modulation can be verified in human malignant melanoma cells.

From adhesion to signalling: roles of integrins in the biology of human melanoma

Integrins are cell surface heterodimers which act as regulators of adhesion and as signal transducers in normal and neoplastic cells. The expression and function of integrins are subject to change during the neoplastic transformation of melanocytes and the progression of melanoma. The integrin profile of human melanoma is also characterized by marked inter- and intratumour heterogeneity. These processes influence the interaction of melanoma cells with extracellular matrix (ECM) components and with other cell types that express integrin ligands. Integrins on melanoma cells not only act as mediators of adhesive interactions but also act as signalling molecules. The signal transducing function of integrins plays a role in a number of biological responses of melanoma cells to ECM-derived stimuli, including production of proteolytic enzymes, invasion of basement membranes, expression of genes and proliferation.

Melanoma cells and normal melanocytes share antigens recognized by HLA-A2-restricted cytotoxic T cell clones from melanoma patients

HLA-A2-restricted, CD3+, CD8+, alpha/beta+ cytotoxic T cell (CTL) clones were isolated from peripheral blood (PBL) or tumor infiltrating lymphocytes (TIL) of two HLA-A2+ melanoma patients (9742 and 5810), to evaluate the possible recognition of autologous melanoma and of allogeneic HLA-A2-matched normal melanocytes. These CTL clones lysed not only fresh and cultured autologous melanoma cells, but also allogeneic HLA-A2+, but not HLA-A2-, normal melanocytes. The lysis of autologous neoplastic cells and of melanocytes could be inhibited by an anti-HLA-A2 monoclonal antibody (mAb). Lysis of the normal melanocytes was not dependent on the presence of human or fetal calf serum in the culture medium. HLA-A2-restricted CTL clones recognized not only proliferating melanocytes cultured in complete melanocyte medium, but also melanocytes made quiescent by culture for up to 6 d in a basal medium devoid of exogenous factors such as phorbol ester (O-tetradecanoyl phorbol 13-acetate [TPA]), epidermal growth factor, insulin, and pituitary extracts. Analysis of specificity of four CTL clones (A75, A83, A94, and 119) from patient 9742, performed on a panel of 39 targets, indicated that the three HLA-A2-restricted CTL (A75, A83, and A94) lysed all but one of nine allogeneic melanomas expressing the HLA-A2 molecule with no reactivity on nine HLA-A2- allogeneic melanomas. Only a few instances of borderline reactivity were seen by the same effectors on 21 targets of nonmelanocyte lineage, including 12 carcinomas of different histology, four Epstein-Barr virus-transformed B cells (lymphoblastoid cell lines [LCL]), including the autologous LCL, four lines of normal fibroblasts, and normal kidney cells. Lack of reactivity on allogeneic targets of nonmelanocyte lineage occurred in spite of expression of HLA-A2 on 14 of these targets as determined by conventional tissue typing and cytofluorimetric analysis with four different anti-HLA-A2 mAb. These data indicate that tissue-related antigens can be expressed on normal and neoplastic cells of the melanocyte lineage and can be recognized in association with HLA-A2 by CTL clones from melanoma patients.

T-cell-receptor engagement and tumor ICAM-1 up-regulation are required to by-pass low susceptibility of melanoma cells to autologous CTL-mediated lysis

Tumor-specific and non-specific CD3+, TcR alpha beta+, CD8+ cytotoxic T-cell (CTL) clones, isolated from tumor-infiltrating lymphocytes (TIL) or peripheral blood lymphocytes (PBL) of a melanoma patient and allogeneic LAK cells, were used to investigate the requirements for bypassing the low lysability of some melanoma clones derived from an s.c. metastasis from which highly lysable clones were also obtained. Cytofluorimetric analysis showed that all melanoma clones expressed ICAM-1, although to different extents, reaching a 10-fold difference in fluorescence units, while HLA class-I antigens were similarly expressed. The differences in expression of ICAM-1 among tumor clones correlated with differences in lysability, by both specific and non-specific CTL, but were not large enough to affect lymphocyte-tumor conjugate formation. Cytokine- or gene-transfer-mediated up-regulation of ICAM-1 did not induce de novo lysis of ICAM-1low tumor cells; however, it markedly enhanced a low level of killing of the same cells by tumor-specific, TcR-dependent and HLA-restricted CTL clones but not by non-specific, TcR-independent effectors. In addition, lysis of melanoma clones by any effector was similarly inhibited by anti-ICAM-1 and anti-LFA-1 antibodies. This indicates that by-pass of low lysability of ICAM-1low melanoma clones by CTL clones, after ICAM-1 up-regulation, is possible only if simultaneous LFA-1 and TcR engagement takes place. In addition, these results suggest that the constitutive high level of expression of ICAM-1 on the subset of ICAM-1high melanoma cells must be only one of the factors contributing to the high lysability of these cells by any effector.

Regulated expression of vascular cell adhesion molecule-1 in human malignant melanoma

Expression of the endothelial adhesion molecule VCAM-1 was studied in human malignant melanoma lines by flow cytometry. Clones 2/4 and 2/14 (derived from the same lesion) had appreciable levels of VCAM-1 expression, whereas clone 2/21 and the lines A2058, Mel24, and A375 were negative. Clone 2/14 was selected for further analysis. Exposure to tumor necrosis factor (TNF) markedly augmented VCAM-1 on melanoma cells. Surface VCAM-1 was associated with expression of specific transcripts that were augmented by TNF. Analysis by reverse transcriptase and polymerase chain reaction using appropriate primers revealed that TNF-stimulated melanoma cells expressed both 7 and 6 immunoglobulin domain transcripts with predominance of the longer species. Tumor necrosis factor--stimulated melanoma cells bound more VLA-4-expressing cells (melanoma and monocytes) than resting tumor cells and anti-VCAM-1 monoclonal antibodies significantly inhibited binding, thus suggesting that surface VCAM-1 on melanoma is functional. Analysis of melanoma tissue sections demonstrated that VCAM-1 is not a marker of transformation of melanocytes because it can be detected in benign nevi. Although, unlike ICAM-1, VCAM-1 is not correlated with tumor progression, its expression in a fraction of primary melanomas indicates that it may play a role in regulating host immune response and homotypic interactions in some malignant melanomas.

Beta 1-integrins on melanoma clones regulate the interaction with autologous cytolytic T-cell clones

Tumor clones isolated from the same subcutaneous metastatic lesion of a melanoma patient were used to investigate the potential role of beta 1-integrins (VLA) in the lysability of neoplastic cells by autologous CD3+, WT31+, CD8+ cytotoxic T-cell clones. Phenotypic analysis of melanoma clones for expression of VLA molecules revealed a subset of clones with high expression of VLA-2, VLA-5, and VLA-6. This subset was also characterized by increased susceptibility to lysis by tumor-specific and nonspecific cytotoxic T-lymphocytes from either TILs or PBLs. Blocking assays with monoclonal antibodies indicated that anti-VLA-2, -5, and -6 antibodies could significantly reduce the lysis of VLA-2+, VLA-5+, and VLA-6+ melanoma clones by either specific and nonspecific CTLs. By contrast, no inhibition was seen on lysis of VLA-2-, VLA-5-, and VLA-6-negative tumor cells. These data indicate that expression of some beta 1-integrins on human melanoma can influence the specific and nonspecific T-cell-mediated recognition of neoplastic cells.

Expansion of major histocompatibility complex-restricted antimelanoma cytotoxic T-cell lymphocyte clones with identical T-cell receptor from tumor-infiltrating lymphocytes

Tumor-infiltrating lymphocytes (TILs) were isolated from a subcutaneous metastasis of melanoma and cytotoxic T-cell lymphocyte (CTL) lines were obtained by sensitizing in vitro four separate aliquots of TILs with autologous tumor cells and recombinant interleukin-2. All CTL lines were predominantly WT31+, CD3+, and CD8+ and displayed a preferential cytotoxic activity against the autologous tumor. T-cell receptor (TCR) composition was analyzed by using the polymerase chain reaction with 5' variable region (V alpha or V beta)-specific primers and 3' constant (C alpha or C beta) primers. The entire repertoire of the V alpha and V beta gene families tested was present in fresh TILs and in the CTL lines, although, in the latter, consistent quantitative variations in transcripts of several V alpha and V beta occurred. CTL clones that exhibited CD3-dependent and major histocompatibility complex-restricted killing of the autologous melanoma were isolated from the four TIL cultures. TCR analysis indicated that, independently from the culture of origin, only two combinations of V alpha and V beta gene families were present in the majority of these CTL clones. These V alpha and V beta gene families were not found in a panel of CTL clones that did not lyse the autologous tumor. This study indicates that recognition of melanoma antigens can strongly select for certain types of TCR-bearing T-lymphocytes.

Cell retargeting by bispecific monoclonal antibodies. Evidence of bypass of intratumor susceptibility to cell lysis in human melanoma

Intratumor heterogeneity for susceptibility to cytotoxic T lymphocytes (CTL)-mediated lysis represents a major obstacle to cancer adoptive immunotherapy. To overcome the heterogeneity observed in terms of susceptibility of target cells to cell-mediated lysis, in this study we used two purified bispecific monoclonal antibodies (bsmAbs) that recognize molecules expressed by cytotoxic effector cells (CD3 and IgG Fc receptorial molecules), as well as one high molecular weight melanoma-associated antigen (HMW-MAA). The ability of these reagents to enhance or induce a relevant in vitro cytotoxic activity by a CTL clone (CTL 49) isolated from PBL of a melanoma patient was tested on a large panel of autologous and allogeneic melanoma cell lines and clones. Functional studies revealed that the CTL 49 clone lysed all the HMW-MAA+ tumor lines in the presence of bsmAbs and that these reagents affected the target lysis in a cooperative fashion. The effectiveness of bsmAbs in overcoming the heterogeneous susceptibility of human melanoma cells to cell-mediated lysis may find practical implications in cancer adoptive immunotherapy.

Role of the alpha 5 beta 1 integrin receptor in the proliferative response of quiescent human melanoma cells to fibronectin

The possible mitogenic activity of fibronectin (FN) in human primary and metastatic melanoma lines and clones and the involvement of integrins in mediating this effect were evaluated. Quescent human melanoma cells cultured in serum-free medium proliferated in a dose- and time-dependent fashion to immobilized FN as indicated by [3H]thymidine incorporation, increment of cell number, and cell cycle analysis. This response to FN was observed with tumor clones isolated from a subcutaneous metastasis and with primary or metastatic melanomas from different patients, but only when tumor cells expressed the alpha 5 subunit of the FN receptor (i.e., VLA-5). Proliferation to FN by a primary tumor (Me4405) expressing all FN receptors and by a tumor clone (2/60) lacking only the alpha 4 subunit was inhibited by monoclonal antibodies to the alpha 5 and beta 1 but not by monoclonal antibodies to other subunits of FN receptors. Mapping of FN regions responsible for the proliferative signal was performed by stimulating melanoma cells with different FN proteolytic fragments and indicated that a significant mitogenic signal was provided by the M(r) 120,000 alpha-chymotrypsin fragment containing the Arg-Gly-Asp sequence. The proliferation of melanoma cells to FN and to FN fragments was also significantly inhibited by peptides containing the Arg-Gly-Asp sequence. These data indicate that FN can stimulate the proliferation of quiescent melanoma cells and that integrins as alpha 5 beta 1 are involved in the response of tumor cells to this extracellular matrix protein.

Two autologous melanoma-specific and MHC-restricted human T cell clones with identical intra-tumour reactivity do not share the same TCR V alpha and V beta gene families

Among tumour infiltrating lymphocytes (TIL) of a melanoma patient, A CD8+, WT31+ CTL clone (8B3) had been previously isolated which exhibited specific and MHC-restricted lytic activity against the autologous tumour. To molecularly characterize T cell receptor (TCR) alpha and beta transcripts of clone 8B3, sequence analysis of several cDNA isolates was carried out. Such analysis indicated that the functional alpha and beta chain of 8B3 are composed of V alpha 2.1/J alpha/C alpha and V beta 8.2/D beta/J beta 1.2/C beta 1 gene segments. Eleven additional melanoma-reactive T cell clones from the same patient (one MHC-restricted and 10 MHC-unrestricted) were analysed for usage of the 8B3 V alpha 2 and V beta 8 gene segments by Northern blot hybridization. Neither the V alpha 2 nor the V beta 8 segments were used by 8D9, the second MHC-restricted melanoma-specific TIL clone that displayed intra-tumour reactivity identical to that of 8B3 recognizing only 4 out of 25 melanoma clones isolated from the same metastases. No V beta 8 expression was found among the MHC-unrestricted T cell clones and all but two (found in duplicate as 4C4 and 4A6) were also negative for V alpha 2 expression. Southern blot analysis revealed different TCR beta chain rearrangements in most MHC-unrestricted T cell clones providing evidence of their independent derivation. Taken together these findings show that TCR of clone 8B3 is unique in composition and not shared by MHC-unrestricted melanoma-reactive T cell clones. The different set of V alpha and V beta families used by clone 8D9 further indicates that the TCR usage in the specific and MHC-restricted response to melanoma can be polyclonal.

Heterogeneity in human melanoma cell adhesion to cytokine activated endothelial cells correlates with VLA-4 expression

Tumor cell attachment to endothelial cells (EC) is one of the critical steps of the metastatic process. It was previously reported that interleukin 1 treatment of EC induces expression of membrane molecules that promote tumor cell adhesion. In this paper we report that a panel of six clones isolated from a human metastatic melanoma presented a marked heterogeneity in their ability to adhere to interleukin 1 activated EC. This was correlated with integrin VLA-4 expression by the clones. Antibodies directed to VLA-4 and to its endothelial ligand INCAM110/VCAM-1 abolished interleukin 1 induced increase in melanoma cell adhesion to EC. These data demonstrate intratumor heterogeneity in the expression of VLA-4 and that this can represent a crucial determinant of tumor cell interaction with EC during secondary spread.

Heterogeneity for integrin expression and cytokine-mediated VLA modulation can influence the adhesion of human melanoma cells to extracellular matrix proteins

Expression of alpha and beta subunits of VLA and VNR integrins was analyzed by cytofluorimetric analysis on 6 different human primary and metastatic melanoma cell cultures. Marked inter-tumor heterogeneity was observed, and expression of VLA-alpha I, VLA-alpha 2 and VLA-alpha 6 was lower on primary melanomas than on metastatic lesions. The function of VLA products on melanoma cells was assessed by adhesion assays to extracellular matrix (ECM) proteins using a panel of melanoma clones previously characterized for the presence and heterogeneity of expression of the distinct VLA-alpha subunits. These experiments indicated that intra-tumor heterogeneity in the integrin profile can influence the interaction of neoplastic cells with ECM proteins. Inhibition of adhesion with antibodies to VLA-alpha subunits revealed that the presence on melanoma cells of VLA-alpha 2, VLA-alpha 5 and VLA-alpha 6 is relevant for the adhesion to type-IV collagen, fibronectin and laminin respectively. Culture of tumor cells in the presence of cytokines such as rIL-I beta, rTNF-alpha, rIFN-gamma or TGF-beta I could induce up- or down-modulation in the level of expression of multiple VLA integrins. Cytokine-mediated antigenic shifts in the VLA profile of melanoma cells were detected by cytofluorimetric analysis as early as 24 hr after cytokine exposure. The cytokine-dependent change in the matrix receptor profile of melanoma cells also affected the adhesion to ECM proteins as revealed by the enhanced adhesion of rTNF-alpha-treated cells to fibronectin. These data indicate that constitutive heterogeneity in the integrin profile or cytokine-mediated shifts in VLA expression can affect the ability of human melanoma cells to interact with different ECM components.

Human melanoma cells with high susceptibility to cell-mediated lysis can be identified on the basis of ICAM-1 phenotype, VLA profile and invasive ability

Marked heterogeneity for susceptibility to lysis by autologous CTL clones and allogeneic IL-2-activated CD3- and CD3+ lymphocytes was found among 19 clones isolated from a human metastatic melanoma (Me665/2). A subset of 5 clones with the highest susceptibility to lysis had increased ICAM-1 antigen expression. Phenotype analysis for the presence of extracellular matrix receptors in the beta 1- and beta 3-integrin families revealed that the tumor clones with the highest susceptibility to lysis were also characterized by frequent expression or increased expression of multiple receptors in the beta 1 family including VLA-1, -2, -3, -4 and -6. The correlation between phenotypic markers and susceptibility to lysis, seen at the clonal level, was confirmed by selection experiments on the uncloned metastasis Me665/2. In fact, the neoplastic population surviving 3 cycles of immunoselection with IL-2-activated lymphocytes exhibited, in comparison to the unselected metastasis: (1) reduced susceptibility to lysis and (2) reduced expression of ICAM-1 and of VLA antigens. In contrast, enhanced susceptibility to lysis and up-regulation of ICAM-1, VLA-1 and VLA-3 antigens were observed on melanoma cells recovered after invading a reconstituted basement membrane. These data indicate that melanoma cells with enhanced susceptibility to cell-mediated lysis can be identified on the basis of phenotypic characteristics (ICAM-1 and VLA antigen profile) and functional features (invasive ability on reconstituted basement membranes).

Multiple VLA antigens on a subset of melanoma clones

A panel of 19 melanoma clones was characterized by fluorescence activated cell sorter analysis for the expression of distinct integrin receptors in the very late activation antibody subfamily. A group of five melanoma clones (2/4, 2/14, 2/17, 2/51, and 2/60) was identified that shared coordinate expression of multiple VLA antigens. These same clones were more susceptible, in terms of lytic units, to cell-mediated lysis and also expressed the lower melanin content per cell in the panel. The data suggest that in a heterogeneous neoplastic population, distinct features such as susceptibility to cell-mediated lysis and expression of receptors for extracellular components are variables preferentially associated with cells in an early stage of differentiation.

Cytokine-mediated modulation of HLA-class II, ICAM-1, LFA-3 and tumor-associated antigen profile of melanoma cells. Comparison with anti-proliferative activity by rIL1-beta, rTNF-alpha, rIFN-gamma, rIL4 and their combinations

Nine different human melanomas and 16 clones, isolated from 2 of them, were characterized for susceptibility to rIL1-beta-, rIL4-, rTNF-alpha- and rIFN-gamma-mediated effects on proliferation and surface expression of class-II HLA (DR and DP), ICAM-1 and LFA-3 molecules and of 3 tumor-associated antigens (recognized by MAb 763.74T, 149.53 and R24). In spite of marked inter- and intra-tumor heterogeneity for susceptibility to the effects of each cytokine, the most frequent upregulation was induced on the HLA class-II antigens by rIFN-gamma and on adhesion molecules by rIFN-gamma, rTNF-alpha and rIL1-beta, while tumor-associated antigens were often down-modulated by rIFN-gamma. Tumor heterogeneity was also evident on tumor-cell proliferation with an apparent hierarchy in the frequency and extent of inhibitory effects: rIFN-gamma greater than rTNF-alpha greater than rIL1-beta = rIL4. Combinations of 2 cytokines resulted in rare and limited changes in the antigenic profile in comparison to the effects seen with single factors, while the combination of rTNF-alpha and rIFN-gamma resulted in significant synergistic antiproliferative effects on most tumor cells and clones. Taken together, these results indicate that single cytokines can profoundly affect the antigenic profile of melanoma cells, while strong tumor-growth inhibition is often achieved by combinations of 2 cytokines acting in synergism.

Phenotypic profile of clones from early cultures of human metastatic melanomas and its modulation by recombinant interferon gamma

Fifty-six tumor clones isolated by cloning in soft agar from early cultures (before the 10th in vitro passage) of two different human metastatic melanomas (Me9229 and Me28) were characterized by FACS analysis for surface expression of class-I and class-II HLA antigens and of melanoma-associated antigens (MAA) with a panel of 15 monoclonal antibodies (MAbs). A marked phenotypic heterogeneity involving MAA and/or HLA markers was observed among the clones derived from both tumors. The differences among the tumor clones and between them and the uncloned melanoma were qualitative and quantitative for each antigen considered. Clones derived from Me9229 expressed the same HLA profile as the parental culture (class I+, class II-) while strong heterogeneity was observed for MAA expression. Clones from Me28 presented a marked heterogeneity for class-I and class-II HLA antigens but were more homogeneous for MAA. The phenotype of the clones was repeatedly checked over the first month in culture and found to remain generally unchanged and not linked to the cell cycle. However, major changes in antigenic expression of the clones could be observed upon treatment with recombinant interferon-gamma (rIFN-gamma): class-I and -II HLA antigens could be induced or augmented while a moderate inhibition was seen on MAA expression. Furthermore, an apparent hierarchy in expression and/or induction of class-II antigens by rIFN-gamma was observed among the tumor clones. DR antigens were more frequently expressed (Me28 clones) and upon treatment with rIFN-gamma reached higher levels than DP and DQ products. Taken together these results indicate that antigenic heterogeneity for MAA and HLA antigens can be detected in cells isolated from early cultures of human metastatic melanomas and suggest that the original uncloned tumor might be considered as a complex mixed population made up of a number of neoplastic cells each expressing a distinct phenotype which can be modulated by lymphokines such as IFN-gamma.