Unique Neoantigens Arise from Somatic Mutations in Patients with Gastrointestinal Cancers.

Immunotherapies can mediate regression of human tumors with high mutation rates, but responses are rarely observed in patients with common epithelial cancers. This raises the question of whether patients with these common cancers harbor T lymphocytes that recognize mutant proteins expressed by autologous tumors that may represent ideal targets for immunotherapy. Using high-throughput immunologic screening of mutant gene products identified via whole-exome sequencing, we identified neoantigen-reactive tumor-infiltrating lymphocytes (TIL) from 62 of 75 (83%) patients with common gastrointestinal cancers. In total, 124 neoantigen-reactive TIL populations were identified, and all but one of the neoantigenic determinants were unique. The results of in vitro T-cell recognition assays demonstrated that 1.6% of the gene products encoded by somatic nonsynonymous mutations were immunogenic. These findings demonstrate that the majority of common epithelial cancers elicit immune recognition and open possibilities for cell-based immunotherapies for patients bearing these cancers. SIGNIFICANCE: TILs cultured from 62 of 75 (83%) patients with gastrointestinal cancers recognized neoantigens encoded by 1.6% of somatic mutations expressed by autologous tumor cells, and 99% of the neoantigenic determinants appeared to be unique and not shared between patients.This article is highlighted in the In This Issue feature, p. 983.

A Phase II Study of Tumor-infiltrating Lymphocyte Therapy for Human Papillomavirus-associated Epithelial Cancers.

PURPOSE: Cellular therapy is an emerging cancer treatment modality, but its application to epithelial cancers has been limited. This clinical trial evaluated tumor-infiltrating lymphocyte (TIL) therapy for the treatment of patients with metastatic human papillomavirus (HPV)-associated carcinomas. PATIENTS AND METHODS: The trial was a phase II design with two cohorts, cervical cancers and noncervical cancers. Cell infusion was preceded by a lymphocyte-depleting conditioning regimen and followed by systemic high-dose aldesleukin. RESULTS: Objective tumor responses occurred in 5 of 18 (28%) patients in the cervical cancer cohort and 2 of 11 (18%) patients in the noncervical cancer cohort. Two of the responses in cervical cancer were complete and are ongoing 67 and 53 months after treatment. Responses in the noncervical cancer cohort were in anal cancer and oropharyngeal cancer. The HPV reactivity of the infused T cells correlated with clinical response. Peripheral blood repopulation with HPV-reactive T cells also correlated with clinical response. CONCLUSIONS: These findings support the concept that cellular therapy can mediate the regression of epithelial cancers, and they suggest the importance of predictive biomarkers and novel treatment platforms for more effective therapies.

T-cell Responses to TP53 "Hotspot" Mutations and Unique Neoantigens Expressed by Human Ovarian Cancers.

Purpose: This was a study prospectively evaluating intratumoral T-cell responses to autologous somatic mutated neoepitopes expressed by human metastatic ovarian cancers.Patients and Methods: Tumor-infiltrating lymphocytes (TIL) were expanded from resected ovarian cancer metastases, which were analyzed by whole-exome and transcriptome sequencing to identify autologous somatic mutations. All mutated neoepitopes, independent of prediction algorithms, were expressed in autologous antigen-presenting cells and then cocultured with TIL fragment cultures. Secretion of IFNγ or upregulation of 41BB indicated a T-cell response.Results: Seven women with metastatic ovarian cancer were evaluated, and 5 patients had clear, dominant T-cell responses to mutated neoantigens, which were corroborated by comparison with the wild-type sequence, identification of the minimal epitope, human leukocyte antigen (HLA) restriction element(s), and neoantigen-specific T-cell receptor(s). Mutated neoantigens were restricted by HLA-B, -C, -DP, -DQ, and/or -DR alleles and appeared to principally arise from random, somatic mutations unique to each patient. We established that TP53 "hotspot" mutations (c.659A>G; p.Y220C and c.733G>A; p.G245S) expressed by two different patients' tumors were both immunogenic in the context of HLA-DRB3*02:02.Conclusions: Mutation-reactive T cells infiltrated ovarian cancer metastases at sufficient frequencies to warrant their investigation as adoptive cell therapy. In addition, transfer of TP53 "hotspot" mutation-reactive T-cell receptors into peripheral blood T cells could be evaluated as a gene therapy for a diverse range of tumor histologies. Clin Cancer Res; 24(22); 5562-73. ©2018 AACR See related commentary by McNeish, p. 5493.

Characterization of an Immunogenic Mutation in a Patient with Metastatic Triple-Negative Breast Cancer.

Purpose: The administration of autologous tumor-infiltrating lymphocytes (TILs) can mediate durable tumor regressions in patients with melanoma likely based on the recognition of immunogenic somatic mutations expressed by the cancer. There are limited data regarding the immunogenicity of mutations in breast cancer. We sought to identify immunogenic nonsynonymous mutations in a patient with triple-negative breast cancer (TNBC) to identify and isolate mutation-reactive TILs for possible use in adoptive cell transfer.Experimental Design: A TNBC metastasis was resected for TIL generation and whole-exome sequencing. Tandem minigenes or long 25-mer peptides encoding selected mutations were electroporated or pulsed onto autologous antigen-presenting cells, and reactivity of TIL was screened by upregulation of CD137 and IFNγ ELISPOT. The nature of the T-cell response against a unique nonsynonymous mutation was characterized.Results: We identified 72 nonsynonymous mutations from the tumor of a patient with TNBC. CD4+ and HLA-DRB1*1501-restricted TILs isolated from this tumor recognized a single mutation in RBPJ (recombination signal binding protein for immunoglobulin kappa J region). Analysis of 16 metastatic sites revealed that the mutation was ubiquitously present in all samples.Conclusions: Breast cancers can express naturally processed and presented unique nonsynonymous mutations that are recognized by a patient's immune system. TILs recognizing these immunogenic mutations can be isolated from a patient's tumor, suggesting that adoptive cell transfer of mutation-reactive TILs could be a viable treatment option for patients with breast cancer. Clin Cancer Res; 23(15); 4347-53. ©2017 AACR.

Treatment of metastatic uveal melanoma with adoptive transfer of tumour-infiltrating lymphocytes: a single-centre, two-stage, single-arm, phase 2 study.

BACKGROUND: Uveal melanoma is a rare tumour with no established treatments once metastases develop. Although a variety of immune-based therapies have shown efficacy in metastatic cutaneous melanoma, their use in ocular variants has been disappointing. Recently, adoptive T-cell therapy has shown salvage responses in multiple refractory solid tumours. Thus, we sought to determine if adoptive transfer of autologous tumour-infiltrating lymphocytes (TILs) could mediate regression of metastatic uveal melanoma. METHODS: In this ongoing single-centre, two-stage, phase 2, single-arm trial, patients (aged ≥16 years) with histologically confirmed metastatic ocular melanoma were enrolled. Key eligibility criteria were an Eastern Cooperative Oncology Group performance status of 0 or 1, progressive metastatic disease, and adequate haematological, renal, and hepatic function. Metastasectomies were done to procure tumour tissue to generate autologous TIL cultures, which then underwent large scale ex-vivo expansion. Patients were treated with lymphodepleting conditioning chemotherapy (intravenous cyclophosphamide [60 mg/kg] daily for 2 days followed by fludarabine [25 mg/m2] daily for 5 days, followed by a single intravenous infusion of autologous TILs and high-dose interleukin-2 [720 000 IU/kg] every 8 h). The primary endpoint was objective tumour response in evaluable patients per protocol using Response to Evaluation Criteria in Solid Tumors, version 1.0. An interim analysis of this trial is reported here. The trial is registered at ClinicalTrials.gov, number NCT01814046. FINDINGS: From the completed first stage and ongoing expansion stage of this trial, a total of 21 consecutive patients with metastatic uveal melanoma were enrolled between June 7, 2013, and Sept 9, 2016, and received TIL therapy. Seven (35%, 95% CI 16-59) of 20 evaluable patients had objective tumour regression. Among the responders, six patients achieved a partial response, two of which are ongoing and have not reached maximum response. One patient achieved complete response of numerous hepatic metastases, currently ongoing at 21 months post therapy. Three of the responders were refractory to previous immune checkpoint blockade. Common grade 3 or worse toxic effects were related to the lymphodepleting chemotherapy regimen and included lymphopenia, neutropenia, and thrombocytopenia (21 [100%] patients for each toxicity); anaemia (14 [67%] patients); and infection (six [29%] patients). There was one treatment-related death secondary to sepsis-induced multiorgan failure. INTERPRETATION: To our knowledge, this is the first report describing adoptive transfer of autologous TILs to mediate objective tumour regression in patients with metastatic uveal melanoma. These initial results challenge the belief that metastatic uveal melanoma is immunotherapy resistant and support the further investigation of immune-based therapies for this cancer. Refinement of this T-cell therapy is crucial to improve the frequency of clinical responses and the general applicability of this treatment modality. FUNDING: Intramural Research Program of the National Institutes of Health, National Cancer Institute, Center for Cancer Research.

A Pilot Trial of the Combination of Vemurafenib with Adoptive Cell Therapy in Patients with Metastatic Melanoma.

PURPOSE: This pilot feasibility clinical trial evaluated the coadministration of vemurafenib, a small-molecule antagonist of BRAFV600 mutations, and tumor-infiltrating lymphocytes (TIL) for the treatment of metastatic melanoma. EXPERIMENTAL DESIGN: A metastatic tumor was resected for growth of TILs, and patients were treated with vemurafenib for 2 weeks, followed by resection of a second lesion. Patients then received a nonmyeloablative preconditioning regimen, infusion of autologous TILs, and high-dose interleukin-2 administration. Vemurafenib was restarted at the time of TIL infusion and was continued for 2 years or until disease progression. Clinical responses were evaluated by Response Evaluation Criteria in Solid Tumors (RECIST) 1.0. Metastases resected prior to and after 2 weeks of vemurafenib were compared using TCRB deep sequencing, immunohistochemistry, proliferation, and recognition of autologous tumor. RESULTS: The treatment was well tolerated and had a safety profile similar to that of TIL or vemurafenib alone. Seven of 11 patients (64%) experienced an objective clinical response, and 2 patients (18%) had a complete response for 3 years (one response is ongoing at 46 months). Proliferation and viability of infusion bag TILs and peripheral blood T cells were inhibited in vitro by research-grade vemurafenib (PLX4032) when approaching the maximum serum concentration of vemurafenib. TCRB repertoire (clonotypes numbers, clonality, and frequency) did not significantly change between pre- and post-vemurafenib lesions. Recognition of autologous tumor by T cells was similar between TILs grown from pre- and post-vemurafenib metastases. CONCLUSIONS: Coadministration of vemurafenib and TILs was safe and feasible and generated objective clinical responses in this small pilot clinical trial. Clin Cancer Res; 23(2); 351-62. ©2016 AACRSee related commentary by Cogdill et al., p. 327.

Randomized, Prospective Evaluation Comparing Intensity of Lymphodepletion Before Adoptive Transfer of Tumor-Infiltrating Lymphocytes for Patients With Metastatic Melanoma.

PURPOSE: Adoptive cell transfer, the infusion of large numbers of activated autologous lymphocytes, can mediate objective tumor regression in a majority of patients with metastatic melanoma (52 of 93; 56%). Addition and intensification of total body irradiation (TBI) to the preparative lymphodepleting chemotherapy regimen in sequential trials improved objective partial and complete response (CR) rates. Here, we evaluated the importance of adding TBI to the adoptive transfer of tumor-infiltrating lymphocytes (TIL) in a randomized fashion. PATIENTS AND METHODS: A total of 101 patients with metastatic melanoma, including 76 patients with M1c disease, were randomly assigned to receive nonmyeloablative chemotherapy with or without 1,200 cGy TBI before transfer of tumor-infiltrating lymphcytes. Primary end points were CR rate (as defined by Response Evaluation Criteria in Solid Tumors v1.0) and overall survival (OS). Clinical and laboratory data were analyzed for correlates of response. RESULTS: CR rates were 24% in both groups (12 of 50 v 12 of 51), and OS was also similar (median OS, 38.2 v 36.6 months; hazard ratio, 1.11; 95% CI, 0.65 to 1.91; P = .71). Thrombotic microangiopathy was an adverse event unique to the TBI arm and occurred in 13 of 48 treated patients. With a median potential follow-up of 40.9 months, only one of 24 patients who achieved a CR recurred. CONCLUSION: Adoptive cell transfer can mediate durable complete regressions in 24% of patients with metastatic melanoma, with median survival > 3 years. Results were similar using chemotherapy preparative regimens with or without addition of TBI.

Prospective identification of neoantigen-specific lymphocytes in the peripheral blood of melanoma patients.

Detection of lymphocytes that target tumor-specific mutant neoantigens--derived from products encoded by mutated genes in the tumor--is mostly limited to tumor-resident lymphocytes, but whether these lymphocytes often occur in the circulation is unclear. We recently reported that intratumoral expression of the programmed cell death 1 (PD-1) receptor can guide the identification of the patient-specific repertoire of tumor-reactive CD8(+) lymphocytes that reside in the tumor. In view of these findings, we investigated whether PD-1 expression on peripheral blood lymphocytes could be used as a biomarker to detect T cells that target neoantigens. By using a high-throughput personalized screening approach, we identified neoantigen-specific lymphocytes in the peripheral blood of three of four melanoma patients. Despite their low frequency in the circulation, we found that CD8(+)PD-1(+), but not CD8(+)PD-1(-), cell populations had lymphocytes that targeted 3, 3 and 1 unique, patient-specific neoantigens, respectively. We show that neoantigen-specific T cells and gene-engineered lymphocytes expressing neoantigen-specific T cell receptors (TCRs) isolated from peripheral blood recognized autologous tumors. Notably, the tumor-antigen specificities and TCR repertoires of the circulating and tumor-infiltrating CD8(+)PD-1(+) cells appeared similar, implying that the circulating CD8(+)PD-1(+) lymphocytes could provide a window into the tumor-resident antitumor lymphocytes. Thus, expression of PD-1 identifies a diverse and patient-specific antitumor T cell response in peripheral blood, providing a novel noninvasive strategy to develop personalized therapies using neoantigen-reactive lymphocytes or TCRs to treat cancer.

Identification of an Immunogenic Subset of Metastatic Uveal Melanoma.

PURPOSE: Uveal melanoma is a rare melanoma variant with no effective therapies once metastases develop. Although durable cancer regression can be achieved in metastatic cutaneous melanoma with immunotherapies that augment naturally existing antitumor T-cell responses, the role of these treatments for metastatic uveal melanoma remains unclear. We sought to define the relative immunogenicity of these two melanoma variants and determine whether endogenous antitumor immune responses exist against uveal melanoma. EXPERIMENTAL DESIGN: We surgically procured liver metastases from uveal melanoma (n = 16) and cutaneous melanoma (n = 35) patients and compared the attributes of their respective tumor cell populations and their infiltrating T cells (TIL) using clinical radiology, histopathology, immune assays, and whole-exomic sequencing. RESULTS: Despite having common melanocytic lineage, uveal melanoma and cutaneous melanoma metastases differed in their melanin content, tumor differentiation antigen expression, and somatic mutational profile. Immunologic analysis of TIL cultures expanded from these divergent forms of melanoma revealed cutaneous melanoma TIL were predominantly composed of CD8(+) T cells, whereas uveal melanoma TIL were CD4(+) dominant. Reactivity against autologous tumor was significantly greater in cutaneous melanoma TIL compared with uveal melanoma TIL. However, we identified TIL from a subset of uveal melanoma patients which had robust antitumor reactivity comparable in magnitude with cutaneous melanoma TIL. Interestingly, the absence of melanin pigmentation in the parental tumor strongly correlated with the generation of highly reactive uveal melanoma TIL. CONCLUSIONS: The discovery of this immunogenic group of uveal melanoma metastases should prompt clinical efforts to determine whether patients who harbor these unique tumors can benefit from immunotherapies that exploit endogenous antitumor T-cell populations. Clin Cancer Res; 22(9); 2237-49. ©2015 AACR.

Immunogenicity of somatic mutations in human gastrointestinal cancers.

It is unknown whether the human immune system frequently mounts a T cell response against mutations expressed by common epithelial cancers. Using a next-generation sequencing approach combined with high-throughput immunologic screening, we demonstrated that tumor-infiltrating lymphocytes (TILs) from 9 out of 10 patients with metastatic gastrointestinal cancers contained CD4(+) and/or CD8(+) T cells that recognized one to three neo-epitopes derived from somatic mutations expressed by the patient's own tumor. There were no immunogenic epitopes shared between these patients. However, we identified in one patient a human leukocyte antigen-C*08:02-restricted T cell receptor from CD8(+) TILs that targeted the KRAS(G12D) hotspot driver mutation found in many human cancers. Thus, a high frequency of patients with common gastrointestinal cancers harbor immunogenic mutations that can potentially be exploited for the development of highly personalized immunotherapies.

Complete regression of metastatic cervical cancer after treatment with human papillomavirus-targeted tumor-infiltrating T cells.

PURPOSE: Metastatic cervical cancer is a prototypical chemotherapy-refractory epithelial malignancy for which better treatments are needed. Adoptive T-cell therapy (ACT) is emerging as a promising cancer treatment, but its study in epithelial malignancies has been limited. This study was conducted to determine if ACT could mediate regression of metastatic cervical cancer. PATIENTS AND METHODS: Patients enrolled onto this protocol were diagnosed with metastatic cervical cancer and had previously received platinum-based chemotherapy or chemoradiotherapy. Patients were treated with a single infusion of tumor-infiltrating T cells selected when possible for human papillomavirus (HPV) E6 and E7 reactivity (HPV-TILs). Cell infusion was preceded by lymphocyte-depleting chemotherapy and was followed by administration of aldesleukin. RESULTS: Three of nine patients experienced objective tumor responses (two complete responses and one partial response). The two complete responses were ongoing 22 and 15 months after treatment, respectively. One partial response was 3 months in duration. The HPV reactivity of T cells in the infusion product (as measured by interferon gamma production, enzyme-linked immunospot, and CD137 upregulation assays) correlated positively with clinical response (P = .0238 for all three assays). In addition, the frequency of HPV-reactive T cells in peripheral blood 1 month after treatment was positively associated with clinical response (P = .0238). CONCLUSION: Durable, complete regression of metastatic cervical cancer can occur after a single infusion of HPV-TILs. Exploratory studies suggest a correlation between HPV reactivity of the infusion product and clinical response. Continued investigation of this therapy is warranted.

Persistence of CTL clones targeting melanocyte differentiation antigens was insufficient to mediate significant melanoma regression in humans.

PURPOSE: Adoptive transfer of autologous tumor infiltrating lymphocytes (TIL) can mediate durable cancer regression in selected patients with metastatic melanoma. However, the tumor antigens associated with these favorable responses remain unclear. We hypothesized that a clinical strategy involving the iterative adoptive transfer of selected autologous antigen-specific T-cell clones could help systematically define immunologic targets associated with successful cancer therapy, without the interpretative ambiguity of transferring polyclonal populations. Here, we evaluated the clinical efficacy of CD8(+) T-cell clones specific for the melanocyte differentiation antigens (MDA), gp100 and MART-1, respectively. EXPERIMENTAL DESIGN: We conducted two consecutive phase II clinical trials involving the adoptive transfer of highly selected autologous antigen-specific CD8(+) T-cell clones against gp100 and MART-1, respectively. Fifteen patients with HLA-A2(+) treatment-refractory metastatic melanoma received highly avid MDA-specific CD8(+) T-cell clones specific for either gp100 (n = 10) or MART-1 (n = 5) with or without intravenous interleukin-2 (IL2) after a lymphodepleting myeloablative preparative regimen. RESULTS: Of the 15 treated patients, we observed immune-mediated targeting of skin melanocytes in 11 patients (73%) and clonal engraftment in eight patients (53%) after cell transfer. There were only transient minor tumor regressions observed, but no objective tumor responses based on Response Evaluation Criteria in Solid Tumor (RECIST) criteria. CONCLUSIONS: Despite successful clonal repopulation and evidence of in vivo antigen targeting, the poor therapeutic efficacy after the adoptive transfer of autologous MDA-specific T cells raises significant concerns regarding future immunotherapy efforts targeting this class of tumor antigens.

A pilot trial using lymphocytes genetically engineered with an NY-ESO-1-reactive T-cell receptor: long-term follow-up and correlates with response.

PURPOSE: Although adoptive cell therapy can be highly effective for the treatment of patients with melanoma, the application of this approach to the treatment of other solid tumors has been limited. The observation that the cancer germline (CG) antigen NY-ESO-1 is expressed in 70% to 80% and in approximately 25% of patients with synovial cell sarcoma and melanoma, respectively, prompted us to perform this first-in-man clinical trial using the adoptive transfer of autologous peripheral blood mononuclear cells that were retrovirally transduced with an NY-ESO-1-reactive T-cell receptor (TCR) to heavily pretreated patients bearing these metastatic cancers. EXPERIMENTAL DESIGN: HLA-*0201 patients with metastatic synovial cell sarcoma or melanoma refractory to standard treatments and whose cancers expressed NY-ESO-1 received autologous TCR-transduced T cells following a lymphodepleting preparative chemotherapy. Response rates using Response Evaluation Criteria in Solid Tumors (RECIST), as well as immunologic correlates of response, are presented in this report. RESULTS: Eleven of 18 patients with NY-ESO-1(+) synovial cell sarcomas (61%) and 11 of 20 patients with NY-ESO-1(+) melanomas (55%) who received autologous T cells transduced with an NY-ESO-1-reactive TCR demonstrated objective clinical responses. The estimated overall 3- and 5-year survival rates for patients with synovial cell sarcoma were 38% and 14%, respectively, whereas the corresponding estimated survival rates for patients with melanoma were both 33%. CONCLUSIONS: The adoptive transfer of autologous T cells transduced with a retrovirus encoding a TCR against an HLA-A*0201 restricted NY-ESO-1 epitope can be an effective therapy for some patients bearing synovial cell sarcomas and melanomas that are refractory to other treatments.

Cancer immunotherapy based on mutation-specific CD4+ T cells in a patient with epithelial cancer.

Limited evidence exists that humans mount a mutation-specific T cell response to epithelial cancers. We used a whole-exomic-sequencing-based approach to demonstrate that tumor-infiltrating lymphocytes (TIL) from a patient with metastatic cholangiocarcinoma contained CD4+ T helper 1 (T(H)1) cells recognizing a mutation in erbb2 interacting protein (ERBB2IP) expressed by the cancer. After adoptive transfer of TIL containing about 25% mutation-specific polyfunctional T(H)1 cells, the patient achieved a decrease in target lesions with prolonged stabilization of disease. Upon disease progression, the patient was retreated with a >95% pure population of mutation-reactive T(H)1 cells and again experienced tumor regression. These results provide evidence that a CD4+ T cell response against a mutated antigen can be harnessed to mediate regression of a metastatic epithelial cancer.

PD-1 identifies the patient-specific CD8⁺ tumor-reactive repertoire infiltrating human tumors.

Adoptive transfer of tumor-infiltrating lymphocytes (TILs) can mediate regression of metastatic melanoma; however, TILs are a heterogeneous population, and there are no effective markers to specifically identify and select the repertoire of tumor-reactive and mutation-specific CD8⁺ lymphocytes. The lack of biomarkers limits the ability to study these cells and develop strategies to enhance clinical efficacy and extend this therapy to other malignancies. Here, we evaluated unique phenotypic traits of CD8⁺ TILs and TCR ß chain (TCRß) clonotypic frequency in melanoma tumors to identify patient-specific repertoires of tumor-reactive CD8⁺ lymphocytes. In all 6 tumors studied, expression of the inhibitory receptors programmed cell death 1 (PD-1; also known as CD279), lymphocyte-activation gene 3 (LAG-3; also known as CD223), and T cell immunoglobulin and mucin domain 3 (TIM-3) on CD8⁺ TILs identified the autologous tumor-reactive repertoire, including mutated neoantigen-specific CD8⁺ lymphocytes, whereas only a fraction of the tumor-reactive population expressed the costimulatory receptor 4-1BB (also known as CD137). TCRß deep sequencing revealed oligoclonal expansion of specific TCRß clonotypes in CD8⁺PD-1⁺ compared with CD8⁺PD-1- TIL populations. Furthermore, the most highly expanded TCRß clonotypes in the CD8⁺ and the CD8⁺PD-1⁺ populations recognized the autologous tumor and included clonotypes targeting mutated antigens. Thus, in addition to the well-documented negative regulatory role of PD-1 in T cells, our findings demonstrate that PD-1 expression on CD8⁺ TILs also accurately identifies the repertoire of clonally expanded tumor-reactive cells and reveal a dual importance of PD-1 expression in the tumor microenvironment.

Human melanoma metastases demonstrate nonstochastic site-specific antigen heterogeneity that correlates with T-cell infiltration.

PURPOSE: Metastasis heterogeneity presents a significant obstacle to the development of targeted cancer therapeutics. In this study, we sought to establish from a large series of human melanoma metastases whether there exists a determined pattern in tumor cellular heterogeneity that may guide the development of future targeted immunotherapies. EXPERIMENTAL DESIGN: From a cohort of 1,514 patients with metastatic melanoma, biopsies were procured over a 17-year period from 3,086 metastatic tumors involving various anatomic sites. To allow specific tumor cell profiling, we used established immunohistochemical methods to perform semiquantitative assessment for a panel of prototypic melanocyte differentiation antigens (MDA), including gp100, MART-1, and tyrosinase. To gain insight into the endogenous host immune response against these tumors, we further characterized tumor cell expression of MHC I and MHC II and, also, the concomitant CD4(+) and CD8(+) T-cell infiltrate. RESULTS: Tumor cell profiling for MDA expression demonstrated an anatomic site-specific pattern of antigen expression that was highest in brain, intermediate in soft tissues/lymph nodes, and lowest in visceral metastases. Hierarchical clustering analysis supported that melanoma metastases have a phylogenetically determined, rather than a stochastic, pattern of antigen expression that varies by anatomic site. Furthermore, tyrosinase expression was more frequently lost in metastatic sites outside of the brain and was uniquely correlated with both endogenous CD8(+) and CD4(+) T-cell infiltrates. CONCLUSION: Site-specific antigen heterogeneity represents a novel attribute for human melanoma metastases that should be considered in future therapy development and when assessing the responsiveness to antigen-specific immunotherapies.

Longitudinal study of recurrent metastatic melanoma cell lines underscores the individuality of cancer biology.

Recurrent metastatic melanoma provides a unique opportunity to analyze disease evolution in metastatic cancer. Here, we followed up eight patients with an unusually prolonged history of metastatic melanoma, who developed a total of 26 recurrences over several years. Cell lines derived from each metastasis were analyzed by comparative genomic hybridization and global transcript analysis. We observed that conserved, patient-specific characteristics remain stable in recurrent metastatic melanoma even after years and several recurrences. Differences among individual patients exceeded within-patient lesion variability, both at the DNA copy number (P<0.001) and RNA gene expression level (P<0.001). Conserved patient-specific traits included expression of several cancer/testis antigens and the c-kit proto-oncogene throughout multiple recurrences. Interestingly, subsequent recurrences of different patients did not display consistent or convergent changes toward a more aggressive disease phenotype. Finally, sequential recurrences of the same patient did not descend progressively from each other, as irreversible mutations such as homozygous deletions were frequently not inherited from previous metastases. This study suggests that the late evolution of metastatic melanoma, which markedly turns an indolent disease into a lethal phase, is prone to preserve case-specific traits over multiple recurrences and occurs through a series of random events that do not follow a consistent stepwise process.

Tumor-reactive CD8+ T cells in metastatic gastrointestinal cancer refractory to chemotherapy.

PURPOSE: To evaluate whether patients with metastatic gastrointestinal adenocarcinomas refractory to chemotherapy harbor tumor-reactive cytotoxic T cells. EXPERIMENTAL DESIGN: Expansion of CD8(+) tumor-infiltrating lymphocytes (TIL) and cancer cell lines was attempted from gastrointestinal cancer metastases in 16 consecutive patients for the study of antitumor immune recognition. Retroviral transduction of genes encoding T-cell receptors (TCR) was used to define HLA-restriction elements and specific reactivity. RESULTS: TIL were expanded from metastases in all patients, and new tumor cell lines were generated in 5 patients. Autologous tumor recognition without cross-reactivity against allogeneic HLA-matched gastrointestinal tumors was found in CD8(+) TIL from 3 of these 5 patients. In a patient with gastric cancer liver metastases, the repertoire of CD8(+) TIL was dominated by cytolytic sister clones reactive to 2 out of 4 autologous cancer cell lines restricted by HLA-C*0701. From the same patient, a rare CD8(+) TIL clone with a distinct TCR recognized all four cancer cell lines restricted by HLA-B*4901. In a patient with bile duct cancer, two distinct antitumor cytolytic clones were isolated from a highly polyclonal CD8(+) TIL repertoire. TCRs isolated from these clones recognized epitopes restricted by HLA-A*0201. In a third patient, CD8(+) TIL reactivity was progressively lost against an autologous colon cancer cell line that displayed loss of HLA haplotype. CONCLUSIONS: This study provides a basis for the development of immunotherapy for patients with advanced gastrointestinal malignancies by first establishing the presence of naturally occurring tumor-reactive CD8(+) TIL at the molecular level.

Gene expression profiling using nanostring digital RNA counting to identify potential target antigens for melanoma immunotherapy.

PURPOSE: The success of immunotherapy for the treatment of metastatic cancer is contingent on the identification of appropriate target antigens. Potential targets must be expressed on tumors but show restricted expression on normal tissues. To maximize patient eligibility, ideal target antigens should be expressed on a high percentage of tumors within a histology and, potentially, in multiple different malignancies. DESIGN: A Nanostring probeset was designed containing 97 genes, 72 of which are considered potential candidate genes for immunotherapy. Five established melanoma cell lines, 59 resected metastatic melanoma tumors, and 31 normal tissue samples were profiled and analyzed using Nanostring technology. RESULTS: Of the 72 potential target genes, 33 were overexpressed in more than 20% of studied melanoma tumor samples. Twenty of those genes were identified as differentially expressed between normal tissues and tumor samples by ANOVA analysis. Analysis of normal tissue gene expression identified seven genes with limited normal tissue expression that warrant further consideration as potential immunotherapy target antigens: CSAG2, MAGEA3, MAGEC2, IL13RA2, PRAME, CSPG4, and SOX10. These genes were highly overexpressed on a large percentage of the studied tumor samples, with expression in a limited number of normal tissue samples at much lower levels. CONCLUSION: The application of Nanostring RNA counting technology was used to directly quantitate the gene expression levels of multiple potential tumor antigens. Analysis of cell lines, 59 tumors, and normal tissues identified seven potential immunotherapy targets for the treatment of melanoma that could increase the number of patients potentially eligible for adoptive immunotherapy.

Phenotype and function of T cells infiltrating visceral metastases from gastrointestinal cancers and melanoma: implications for adoptive cell transfer therapy.

Adoptive cell transfer of tumor-infiltrating lymphocytes (TILs) can mediate cancer regression in patients with metastatic melanoma, but whether this approach can be applied to common epithelial malignancies remains unclear. In this study, we compared the phenotype and function of TILs derived from liver and lung metastases from patients with gastrointestinal (GI) cancers (n = 14) or melanoma (n = 42). Fewer CD3(+) T cells were found to infiltrate GI compared with melanoma metastases, but the proportions of CD8(+) cells, T cell differentiation stage, and expression of costimulatory molecules were similar for both tumor types. Clinical-scale expansion up to ~50 × 10(9) T cells on average was obtained for all patients with GI cancer and melanoma. From GI tumors, however, TIL outgrowth in high-dose IL-2 yielded 22 ± 1.4% CD3(+)CD8(+) cells compared with 63 ± 2.4% from melanoma (p < 0.001). IFN-γ ELISA demonstrated MHC class I-mediated reactivity of TIL against autologous tumor in 5 of 7 GI cancer patients tested (9% of 188 distinct TIL cultures) and in 9 of 10 melanoma patients (43% of 246 distinct TIL cultures). In these assays, MHC class I-mediated up-regulation of CD137 (4-1BB) expression on CD8(+) cells suggested that 0-3% of TILs expanded from GI cancer metastases were tumor-reactive. This study implies that the main challenge to the development of TIL adoptive cell transfer for metastatic GI cancers may not be the in vitro expansion of bulk TILs, but the ability to select and enrich for tumor-reactive T cells.