Histologic subtypes of breast cancer following radiotherapy for Hodgkin lymphoma.

BACKGROUND: The purpose of the study was to determine whether breast cancers (BCs) that develop in women previously irradiated for Hodgkin lymphoma (HL) are biologically similar to sporadic BC. MATERIALS AND METHODS: We retrospectively reviewed the charts of patients who developed BC after radiotherapy (RT) for HL. Tumors were classified as ductal carcinoma in situ (DCIS) or invasive carcinoma. Invasive carcinomas were further characterized according to the subtype: hormone receptor (HR)+/human epidermal growth factor receptor 2 (HER2)-, HR+/HER2+, HR-/HER2+, and HR-/HER2-. BCs after HL were compared with four age-matched sporadic, non-breast cancer (BRCA) I or II mutated BCs. RESULTS: One hundred forty-seven HL patients who were treated with RT between 1966 and 1999 and subsequently developed BCs were identified. Of these, 65 patients with 71 BCs had complete pathologic information. The median age at HL diagnosis was 23 (range, 10-48). The median age at BC diagnosis was 44 (range, 28-66). The median time to developing BC was 20 years. Twenty cancers (28%) were DCIS and 51 (72%) were invasive. Of the 51 invasive cancers, 24 (47%) were HR+/HER2-, 2 (4%) were HR+/HER2+, 5 (10%) were HR-/HER2+, and 20 (39%) were HR-/HER2-. There were no differences in BC histologic subtype according to the age at which patients were exposed to RT, the use of chemotherapy for HL treatment, or the time from RT exposure to the development of BC. In a 4 : 1 age-matched comparison to sporadic BCs, BCs after HL were more likely to be HR-/HER2- (39% versus 14%) and less likely to be HR+/HER2- (47% versus 61%) or HR+/HER2+ (4% versus 14%) (P = 0.0003). CONCLUSION(S): BCs arising in previously irradiated breast tissue were more likely to be triple negative compared with age-matched sporadic invasive cancers and less likely to be HR positive. Further studies will be important to determine the molecular pathways of carcinogenesis in breast tissue that is exposed to RT.

Inhibition of TGF-ß signaling in genetically engineered tumor antigen-reactive T cells significantly enhances tumor treatment efficacy.

Transforming growth factor ß (TGF-ß) is a cytokine with complex biological functions that may involve tumor promotion or tumor suppression. It has been reported that multiple types of tumors secrete TGF-ß, which can inhibit tumor-specific cellular immunity and may represent a major obstacle to the success of tumor immunotherapy. In this study, we sought to enhance tumor immunotherapy using genetically modified antigen-specific T cells by interfering with TGF-ß signaling. We constructed three γ-retroviral vectors, one that expressed TGF-ß-dominant-negative receptor II (DNRII) or two that secreted soluble TGF-ß receptors: soluble TGF-ß receptor II (sRII) and the sRII fused with mouse IgG Fc domain (sRIIFc). We demonstrated that T cells genetically modified with these viral vectors were resistant to exogenous TGF-ß-induced smad-2 phosphorylation in vitro. The functionality of antigen-specific T cells engineered to resist TGF-ß signaling was further evaluated in vivo using the B16 melanoma tumor model. Antigen-specific CD8+ T cells (pmel-1) or CD4+ T cells (tyrosinase-related protein-1) expressing DNRII dramatically improved tumor treatment efficacy. There was no enhancement in the B16 tumor treatment using cells secreting soluble receptors. Our data support the potential application of the blockade of TGF-ß signaling in tumor-specific T cells for cancer immunotherapy.

CXCR3/CCR5 pathways in metastatic melanoma patients treated with adoptive therapy and interleukin-2.

BACKGROUND: Adoptive therapy with tumour-infiltrating lymphocytes (TILs) induces durable complete responses (CR) in ∼20% of patients with metastatic melanoma. The recruitment of T cells through CXCR3/CCR5 chemokine ligands is critical for immune-mediated rejection. We postulated that polymorphisms and/or expression of CXCR3/CCR5 in TILs and the expression of their ligands in tumour influence the migration of TILs to tumours and tumour regression. METHODS: Tumour-infiltrating lymphocytes from 142 metastatic melanoma patients enrolled in adoptive therapy trials were genotyped for CXCR3 rs2280964 and CCR5-Δ32 deletion, which encodes a protein not expressed on the cell surface. Expression of CXCR3/CCR5 in TILs and CXCR3/CCR5 and ligand genes in 113 available parental tumours was also assessed. Tumour-infiltrating lymphocyte data were validated by flow cytometry (N=50). RESULTS: The full gene expression/polymorphism model, which includes CXCR3 and CCR5 expression data, CCR5-Δ32 polymorphism data and their interaction, was significantly associated with both CR and overall response (OR; P=0.0009, and P=0.007, respectively). More in detail, the predicted underexpression of both CXCR3 and CCR5 according to gene expression and polymorphism data (protein prediction model, PPM) was associated with response to therapy (odds ratio=6.16 and 2.32, for CR and OR, respectively). Flow cytometric analysis confirmed the PPM. Coordinate upregulation of CXCL9, CXCL10, CXCL11, and CCL5 in pretreatment tumour biopsies was associated with OR. CONCLUSION: Coordinate overexpression of CXCL9, CXCL10, CXCL11, and CCL5 in pretreatment tumours was associated with responsiveness to treatment. Conversely, CCR5-Δ32 polymorphism and CXCR3/CCR5 underexpression influence downregulation of the corresponding receptors in TILs and were associated with likelihood and degree of response.

Efficacy of abbreviated Stanford V chemotherapy and involved-field radiotherapy in early-stage Hodgkin lymphoma: mature results of the G4 trial.

INTRODUCTION: To assess the efficacy of an abbreviated Stanford V regimen in patients with early-stage Hodgkin lymphoma (HL). PATIENTS AND METHODS PATIENTS: with untreated nonbulky stage I-IIA supradiaphragmatic HL were eligible for the G4 study. Stanford V chemotherapy was administered for 8 weeks followed by radiation therapy (RT) 30 Gy to involved fields (IF). Freedom from progression (FFP), disease-specific survival (DSS) and overall survival (OS) were estimated. RESULTS: All 87 enrolled patients completed the abbreviated regimen. At a median follow-up of 10 years, FFP, DSS and OS are 94%, 99% and 94%, respectively. Therapy was well tolerated with no treatment-related deaths. CONCLUSIONS: Mature results of the abbreviated Stanford V regimen in nonbulky early-stage HL are excellent and comparable to the results from other contemporary therapies.

A T cell-independent antitumor response in mice with bone marrow cells retrovirally transduced with an antibody/Fc-gamma chain chimeric receptor gene recognizing a human ovarian cancer antigen.

In order to treat common cancers with immunotherapy, chimeric receptors have been developed that combine the tumor specificity of antibodies with T-cell effector functions. Previously, we demonstrated that T cells transduced with a chimeric receptor gene against human ovarian cancer were able to recognize ovarian cancer cells in vitro and in vivo. We now report that recipients of bone marrow cells transduced with these genes exhibited significant antitumor activity in vivo. Moreover, in vivo depletion of T cells in reconstituted mice did not affect antitumor activity, suggesting that other immune cells expressing the chimeric receptor gene may play an important role in tumor rejection.

Immunologic and therapeutic evaluation of a synthetic peptide vaccine for the treatment of patients with metastatic melanoma.

The cloning of the genes encoding cancer antigens has opened new possibilities for the treatment of patients with cancer. In this study, immunodominant peptides from the gp100 melanoma-associated antigen were identified, and a synthetic peptide, designed to increase binding to HLA-A2 molecules, was used as a cancer vaccine to treat patients with metastatic melanoma. On the basis of immunologic assays, 91% of patients could be successfully immunized with this synthetic peptide, and 13 of 31 patients (42%) receiving the peptide vaccine plus IL-2 had objective cancer responses, and four additional patients had mixed or minor responses. Synthetic peptide vaccines based on the genes encoding cancer antigens hold promise for the development of novel cancer immunotherapies.

Delta radiomics analysis of Magnetic Resonance guided radiotherapy imaging data can enable treatment response prediction in pancreatic cancer.

BACKGROUND: Magnetic Resonance Image guided Stereotactic body radiotherapy (MRgRT) is an emerging technology that is increasingly used in treatment of visceral cancers, such as pancreatic adenocarcinoma (PDAC). Given the variable response rates and short progression times of PDAC, there is an unmet clinical need for a method to assess early RT response that may allow better prescription personalization. We hypothesize that quantitative image feature analysis (radiomics) of the longitudinal MR scans acquired before and during MRgRT may be used to extract information related to early treatment response. METHODS: Histogram and texture radiomic features (n = 73) were extracted from the Gross Tumor Volume (GTV) in 0.35T MRgRT scans of 26 locally advanced and borderline resectable PDAC patients treated with 50 Gy RT in 5 fractions. Feature ratios between first (F1) and last (F5) fraction scan were correlated with progression free survival (PFS). Feature stability was assessed through region of interest (ROI) perturbation. RESULTS: Linear normalization of image intensity to median kidney value showed improved reproducibility of feature quantification. Histogram skewness change during treatment showed significant association with PFS (p = 0.005, HR = 2.75), offering a potential predictive biomarker of RT response. Stability analyses revealed a wide distribution of feature sensitivities to ROI delineation and was able to identify features that were robust to variability in contouring. CONCLUSIONS: This study presents a proof-of-concept for the use of quantitative image analysis in MRgRT for treatment response prediction and providing an analysis pipeline that can be utilized in future MRgRT radiomic studies.

Successful immunotherapy of natural killer-resistant established pulmonary melanoma metastases by the intravenous adoptive transfer of syngeneic lymphocytes activated in vitro by interleukin 2.

In previous in vitro studies, we have shown that murine splenocytes or cancer patient lymphocytes incubated in IL-2 become lytic for fresh syngeneic or autologous tumors. We have now performed the adoptive transfer of such lymphokine-activated killer (LAK) cells in a murine B16 metastasis model to test their in vivo efficacy. 1 X 10(8) LAK cells, infused intravenously into C57BL/6 mice with established B16 pulmonary metastases, led to a marked decreased in the number of lung nodules and improved survival. LAK cells administered 3 d after amputation of a tumor-bearing limb also decreased the incidence of spontaneous pulmonary metastases. LAK cells generated from tumor-bearer splenocytes had effects equivalent to those from normal animals, and this antimetastatic effect of the LAK cells did not require the prior administration of cyclophosphamide or other immunosuppressants. Fresh or unstimulated splenocytes had no effect. The antitumor effectors and precursors in vivo and in vitro were Thy-1+. The lymphokine required for the activation appeared to be interleukin 2 (IL-2), since incubation in partially purified supernatants from PMA pulsed EL-4 or Con A-pulsed splenocytes or purified Jurkat IL-2 led to the generation of LAK cells equally active in vivo. The use of IL-2-activated cells may provide a valuable method for the adoptive therapy of human neoplasms as well.

Immunization with antigen and interleukin 2 in vivo overcomes Ir gene low responsiveness.

We studied the effect of purified interleukin 2 (IL-2), made by recombinant DNA techniques, on the serum antibody response to myoglobin in high- and low-responder mice. Previous studies (6, 7) have shown that this response is controlled by H-2-linked Ir genes. The IL-2 was emulsified with the antigen in complete Freund's adjuvant to provide a sustained high local concentration. In low-responder B10.BR mice, a single dose (optimum 50,000 U) resulted in a consistent 10-50-fold increase in specific serum antibody throughout the time course of the response, from 10 d to 46 d after immunization. In contrast, no effect of IL-2 was seen in congenic high-responder B10.D2 mice. With IL-2, the low-responder mice achieved specific antibody levels comparable to those of high responders. Vehicle alone had no effect, and IL-2 alone, without antigen, did not induce myoglobin-specific antibody. No effect of IL-2 was seen in athymic nude mice of high-responder H-2 haplotype. The effect of IL-2 may be on a small number of responding T cells in the low responder mice, but it is possible that IL-2 also acts directly on B cells in a response that remains T-dependent, and therefore is not observed in athymic mice. We suggest that IL-2 may enhance suboptimal T cell help in the low responder, whereas help is not limiting in the high responder. This approach may enable the study of antibody responses in low responders otherwise too weak to analyze, and may be useful in producing antibodies to poorly immunogenic antigens. Potential clinical uses include immunization with weak antigens in normal patients, or with any antigen in certain immunodeficient patients.

Interleukin 4 promotes the growth of tumor-infiltrating lymphocytes cytotoxic for human autologous melanoma.

Addition of IL-4 (1,000 U/ml) to either high or low concentrations of IL-2 augmented tumor-infiltrating lymphocytes (TIL) growth from human melanoma. Weekly restimulation with irradiated tumor cells in conjunction with IL-4 allowed enhanced growth of TIL. With low-dose IL-2 (10 U/ml) and IL-4, expanded TIL had little cytolytic activity against Daudi or allogeneic tumors. Further, IL-4 augmented the total lytic activity against autologous tumors in most cases. With high-dose IL-2 (1,000 U/ml), IL-4 addition decreased nonspecific killing activity against Daudi or allogeneic melanomas in many cases, and reciprocally augmented cytolytic activity against the autologous melanoma in many cases. This suggests the possible use of IL-4 in cancer therapy, especially in adoptive cellular immunotherapy using TIL or in conjunction with IL-2 administration.

Regression of a disseminated syngeneic solid tumor by systemic transfer of lymphoid cells expanded in interleukin 2.

We have studied the ability of immunized lymphoid cells expanded in IL-2 to mediate the cure of mice with localized and disseminated syngeneic lymphoma. Mice received 500 rad total-body irradiation before injection of tumor into the footpad. Mice were treated 5 d later when a palpable local tumor and disseminated metastases were present. Intravenous injection of in vivo immune lymphocytes cured 93% of all mice, significantly better than any control group (P less than 0.0005). Immune cells, secondarily sensitized to the FBL-3 tumor in vitro, also conferred significant survival benefit (P less than 0.005) when injected intravenously, curing 79% of the animals treated. When these in vitro sensitized cells were expanded in IL-2, 8-10-fold over 7 d, 93% of the animals thus treated were cured, (P less than 0.005). When these cells were grown for multiple generations in IL-2 they retained their ability to cure mice (56% cured, P less than 0.01). This is the first demonstration that intravenous injection of sensitized cells grown in long term culture in IL-2 is capable of curing mice of established local and disseminated syngeneic tumor.

Identification of a novel major histocompatibility complex class II-restricted tumor antigen resulting from a chromosomal rearrangement recognized by CD4(+) T cells.

CD4(+) T cells play an important role in antitumor immune responses and autoimmune and infectious diseases. Although many major histocompatibility complex (MHC) class I-restricted tumor antigens have been identified in the last few years, little is known about MHC class II- restricted human tumor antigens recognized by CD4(+) T cells. Here, we describe the identification of a novel melanoma antigen recognized by an human histocompatibility leukocyte antigen (HLA)-DR1-restricted CD4(+) tumor-infiltrating lymphocyte (TIL)1363 using a genetic cloning approach. DNA sequencing analysis indicated that this was a fusion gene generated by a low density lipid receptor (LDLR) gene in the 5' end fused to a GDP-L-fucose:beta-D-galactoside 2-alpha-L-fucosyltransferase (FUT) in an antisense orientation in the 3' end. The fusion gene encoded the first five ligand binding repeats of LDLR in the NH2 terminus followed by a new polypeptide translated in frame with LDLR from the FUT gene in an antisense direction. Southern blot analysis showed that chromosomal DNA rearrangements occurred in the 1363mel cell line. Northern blot analysis detected two fusion RNA transcripts present only in the autologous 1363mel, but not in other cell lines or normal tissues tested. Two minimal peptides were identified from the COOH terminus of the fusion protein. This represents the first demonstration that a fusion protein resulting from a chromosomal rearrangement in tumor cells serves as an immune target recognized by CD4(+) T cells.

Interleukin 7 generates antitumor cytotoxic T lymphocytes against murine sarcomas with efficacy in cellular adoptive immunotherapy.

Interleukin 7 (IL-7) is a 25-kD cytokine that was initially described as a pre-B cell growth factor. This cytokine has also been shown to have T cell proliferative and differentiation effects. In this report, we demonstrate that antitumor cytotoxic T lymphocytes (CTL) generated by secondary in vitro sensitization of draining lymph node cells in IL-7 are effective in treating 3-day syngeneic methylcholanthrene (MCA) sarcoma pulmonary metastases in mice. In vivo titrations comparing IL-7 to IL-2 antitumor CTL show that they have equivalent potency in adoptive immunotherapy. IL-7 antitumor CTL generated against MCA sarcomas of weak immunogeneity are also tumor specific in their in vivo efficacy. This study represents the first successful use of a cytokine other than IL-2 for the generation of cells with in vivo efficacy in cellular adoptive transfer.

Synergistic antitumor activity of tumor-infiltrating lymphocytes, interleukin 2, and local tumor irradiation. Studies on the mechanism of action.

The adoptive transfer of tumor-infiltrating lymphocytes (TIL) with the concomitant administration of IL-2 has been shown to mediate the regression of established 6- and 14-d murine hepatic and pulmonary metastases. For successful immunotherapy with TIL, however, pretreatment with either cyclophosphamide (CP) or whole body irradiation (WBX) was required. The exact mechanism of CP and WBX augmentation of TIL antitumor activity remains unknown, but the elimination of Ts cells has been frequently invoked as an explanation. To address this possibility and to determine if local tumor irradiation (LTX) could synergize with TIL as well as WBX, we investigated the effect of LTX on the therapeutic efficacy of TIL and IL-2 in the treatment of multiple 7-d murine hepatic metastases. Experiments studying the treatment of a weakly immunogenic murine adenocarcinoma, MC-38, showed prolonged survival of mice treated with the combination of IL-2, TIL, and either LTX or WBX, compared with treatment with radiation alone or radiation plus IL-2 controls (p less than 0.0001). In addition, therapy with LTX and IL-2 prolonged survival, compared with LTX administration alone, whereas therapy with WBX combined with IL-2 did not alter survival. This augmentation of TIL-mediated antitumor activity was dependent on the dose of radiation used. To assess the possibility that tumor-associated Ts cells inhibit the function of adoptively transferred TIL in animals with 7-d metastatic tumor and are eliminated by WBX and LTX, we repeated the above experiments leaving some tumor unirradiated. Mice underwent either LTX or limited LTX, which included only the right side of the liver (LTX1/2). The number of right- and left-sided metastases were then individually counted. These studies showed that the reduction in the number of right-sided metastases was identical between the two groups and that the presence of left-sided tumor in the LTX1/2 group did not suppress the observed antitumor activity of TIL against irradiated tumor. Additional evidence against the elimination of suppressor cells as an important mechanism in radiation-induced augmentation of TIL antitumor activity was provided by experiments studying the effectiveness of TIL in thymectomized, lethally irradiated, and reconstituted B mice. Unless CP was administered before the adoptive transfer of TIL, therapy with IL-2 and TIL in these B mice was ineffective in the absence of demonstrable T lymphocytes.(ABSTRACT TRUNCATED AT 400 WORDS)

Lymphokine-activated killer cell phenomenon. Lysis of natural killer-resistant fresh solid tumor cells by interleukin 2-activated autologous human peripheral blood lymphocytes.

Activation in lectin-free interleukin 2 (IL-2) containing supernatants of peripheral blood mononuclear leukocytes (PBL) from cancer patients or normal individuals resulted in expression of cytotoxicity toward 20 of 21 natural killer (NK)-resistant fresh solid tumor cells tested. Fresh solid tumor cells were resistant to NK-mediated lysis in 10 autologous patients' PBL-tumor interactions, and from 17 normal individuals tested against 13 allogeneic fresh tumors. Culture of PBL in IL-2 for 2-3 d was required for the lymphokine activated killers (LAK) to be expressed, and lytic activity toward a variety of NK-resistant fresh and cultured tumor targets developed in parallel. Autologous IL-2 was functional in LAK activation, as well as interferon-depleted IL-2 preparations. Irradiation of responder PBL before culture in IL-2 prevented LAK development. Precursors of LAK were present in PBL depleted of adherent cells and in NK-void thoracic duct lymphocytes, suggesting that the precursor is neither a monocyte nor an NK cell. LAK effectors expressed the serologically defined T cell markers of OKT.3, Leu-1, and 4F2, but did not express the monocyte/NK marker OKM-1. Lysis of autologous fresh solid tumors by LAK from cancer patients' PBL was demonstrated in 85% of the patient-fresh tumor combinations. Our data present evidence that the LAK system is a phenomenon distinct from either NK or CTL systems that probably accounts for a large number of reported nonclassical cytotoxicities. The biological role of LAK cells is not yet known, although it is suggested that these cells may be functional in immune surveillance against human solid tumors.

Immunotherapy of a murine tumor with interleukin 2. Increased sensitivity after MHC class I gene transfection.

We have shown that two weakly immunogenic MCA sarcomas developed in our laboratory that are sensitive to high-dose IL-2 immunotherapy express class I MHC in vivo and in vitro. Two nonimmunogenic MCA sarcomas are relatively insensitive to IL-2 therapy and express minimal or no class I MHC molecules in vivo and in vitro. To study the role of MHC in the therapy of tumors with IL-2, a class I-deficient murine melanoma, B16BL6, was transfected with the Kb class I gene. Expression of class I MHC rendered B16BL6 advanced pulmonary macrometastases sensitive to IL-2 immunotherapy. 3-d micrometastases of CL8-2, a class I transfected clone of B16BL6, were significantly more sensitive to IL-2 therapy than a control nontransfected line. Expression of Iak, a class II MHC molecule, had no effect on IL-2 therapy of transfectant pulmonary micrometastases in F1 mice. By using lymphocyte subset depletion with mAbs directed against Lyt-2, therapy of class I transfectant macrometastases with high-dose IL-2 was shown to involve an Lyt-2 cell. In contrast, regression of micrometastases treated with low-dose IL-2 involved Lyt-2+ cells, but regression mediated by high doses of IL-2 did not. We hypothesize that both LAK and Lyt-2+ T cells effect IL-2-mediated elimination of micrometastases, but only Lyt-2+ T cells are involved in macrometastatic regression. Low doses of IL-2 stimulate Lyt-2+ cells to eliminate class I-expressing micrometastases, but high doses of IL-2 can recruit LAK cells to mediate regression of micrometastases independent of class I expression. Only high-dose IL-2, mediating its effect predominantly via Lyt-2+ cells, is capable of impacting on MHC class I-expressing macrometastases. Macrometastases devoid of class I MHC antigens appear to be resistant to IL-2 therapy.

Interleukin 4 (B cell stimulatory factor 1) can mediate the induction of lymphokine-activated killer cell activity directed against fresh tumor cells.

Interleukin 4 (IL-4) expresses multiple biologic activities, including B cell, mast cell, and T cell stimulation. We showed that the incubation of resting splenocytes from C57BL/6 mice solely in purified native or recombinant mouse IL-4 results in the generation of lymphokine-activated killer (LAK) activity directed against fresh, syngeneic sarcoma cells. The precursor activated by IL-4 expresses surface asialo-GM1. In addition, IL-4 is capable of amplifying the splenic LAK activity induced by recombinant IL-2. The generation, by IL-4, of killer cells with broad antitumor reactivity raises the possibility of using IL-4 alone or in combination with IL-2 in the immunotherapy of cancer in animal models.

Regression of established pulmonary metastases and subcutaneous tumor mediated by the systemic administration of high-dose recombinant interleukin 2.

Incubation of resting lymphoid cells with recombinant interleukin 2 (IL-2) in vitro leads to the generation of lymphokine activated killer (LAK) cells capable of lysing fresh tumor cell suspensions in short-term chromium-release assays. Our previous studies (7) have demonstrated that the injection of LAK cells plus low doses of recombinant IL-2 were capable of inhibiting the growth of pulmonary metastases. We have now explored the ability of high doses of recombinant IL-2, administered systemically, to generate LAK cells in vivo, and to mediate antitumor effects directly. Administration of increasing doses of recombinant IL-2 intraperitoneally resulted in the generation of LAK cells in the spleens of recipient mice. Doses of 100,000 U recombinant IL-2 administered intraperitoneally approximately every 8 h for 5 d were capable of dramatically inhibiting established 3-d pulmonary metastases from the MCA-105 and MCA-106 syngeneic sarcomas and the syngeneic B16 melanoma in C57BL/6 mice. Grossly visible metastases present at 10 d after tumor injection also underwent regression following IL-2 therapy. Surprisingly, established 10 d pulmonary metastases were more susceptible to the effects of IL-2 than were the smaller 3 d pulmonary metastases. All antitumor effects of the systemic administration of recombinant IL-2 were eliminated if mice received prior treatment with 500 rad total body irradiation. The administration of high doses of recombinant IL-2 was also capable of inhibiting the growth of 3-d established subcutaneous tumors from the MCA-105 sarcoma, and of mediating the inhibition of growth and regression of established palpable subcutaneous MCA-105 sarcomas. Lymphocytes, which appeared morphologically to be activated, were present at the site of regressing tumor, and it appears that the mechanism of the antitumor effect of recombinant IL-2 administered systemically is via the generation of LAK cells in vivo, although this hypothesis remains to be proven. The ready availability of high doses of recombinant human IL-2, and the demonstration of antitumor effects seen in animal models have led us to the initiation of the clinical trials of recombinant IL-2 in humans.

Identification of TRP-2 as a human tumor antigen recognized by cytotoxic T lymphocytes.

The infusion of TIL586 along with interleukin-2 into the autologous patient with metastatic melanoma resulted in the objective regression of tumor. A gene encoding a tumor antigen recognized by TIL586 was previously isolated and shown to encode gp75 or TRP-1. Here we report that TRP-2 was identified as a second tumor antigen recognized by a HLA-A31-restricted CTL clone derived from the TIL586 cell line. The peptide LLPGGRPYR epitope was subsequently identified from the coding region of TRP-2 based on studies of the recognition of truncated TRP-2 cDNAs and the HLA-A31 binding motif. This epitope peptide was capable of sensitizing target cells for lysis by a CTL clone at 1 nM peptide concentration. Although some modified peptides could be recognized by the CTL clone, none were found to be better recognized by T cells than the parental peptide. Like other melamona differentiation antigens, TRP-2 was only expressed in melanoma, melanocytes, and retina, but not in other human tissues tested.

Identification of a gene encoding a melanoma tumor antigen recognized by HLA-A31-restricted tumor-infiltrating lymphocytes.

The availability of antitumor cytotoxic T lymphocytes which can be generated from either peripheral blood lymphocytes after stimulation in vitro or tumor infiltrating lymphocytes (TIL) has made it possible to identify a number of melanoma antigens presented by major histocompatibility complex class I molecules. The present and previous studies indicated that TIL586 recognized an antigen expressed on most melanoma and normal melanocytes in the context of the HLA-A31 molecule. We report here the cloning of a cDNA that directs the expression of the shared melanoma antigen recognized by this TIL. The DNA sequence analysis revealed that the cDNA was almost identical to the gene encoding tyrosinase-related protein 1 or glycoprotein gp75 which was originally identified by serum antibodies in a patient with melanoma. The gene was found to be expressed only in melanoma, normal melanocyte cell lines, and retina, but not in other normal tissues tested. The gp75 antigen presented by HLA-A31 may therefore constitute a useful immune target for specific treatment of patients with melanoma, since both antibody- and T cell-mediated immune responses can be generated against this antigen.