IL15CanReversetheUnresponsivenessofWilms’Tumor Antigen-SpecificCTLinPatientswithProstateCancer Judy W.King, 1 Sharyn Thomas, 1 FabrizioCorsi, 6 LiquanGao, 1 RobertoDina, 4 Roopinder Gillmore, 2 KatharinePigott, 2 AmirKaisary, 3 Hans J.Stauss, 1 andJonathan Waxman 5 Abstract Purpose: TheWilms’tumorantigen1(WT1 )isoverexpressedinseveralleukemiasandsolid tumors,butthereiscurrentlylimitedinformationregardingitsroleinprostatecancer.Thisstudy aimedtoinvestigate WT1 expressioninprostatecancer,andtodeterminethenumberandfunction of WT1-specificTcellsintheperipheralbloodofpatients. ExperimentalDesign: Immunohistochemistry wasusedtoassess WT1 expressionincancer tissues.HumanleukocyteantigenA2(HLA-A2)tetramersservedtodetect WT1-specificTcells, andpeptide-specificstimulationwasusedtoassessT-cellfunction in vitro. Results: Immunohistochemistry of tissue arrays comprising 36 cancer and 8 normalprostate samples revealednuclear WT1 stainingin39%ofcancersamples,butnotinnormalprostate tissues.Tetrameranalysisrevealedalowfrequencyof WT1-specificTcellsin20of38HLA-A2^ positivepatients. In vitro stimulation with WT1 peptide plus interleukin 2(IL2) andinterleukin 7 (IL7) did not lead to an accumulation of WT1-specificTcells in any of the patient samples, although all patients were able to generateT-cell responses against Melan-A/MART1control peptide. Stimulation with WT1 peptide in the presence of interleukin15 (IL15), a cytokine that wasshowntoreversetoleranceofmurinetumor-specificTcells,wasabletorestoretheexpansion andIFNg productionof WT1 -specificTcellsinasubgroupofprostatecancerpatients. Conclusion: TheobservationthatIL15canrestorethefunctionof WT1 -specificTcellsthatwere unresponsivetoIL2hasimplicationsfor vaccinationandimmunotherapeuticstrategiesthataim toenhance WT1-specificTcellimmunityinpatients. Prostate cancer is the most common cancer in men in Europe and North America, and the incidence worldwide is increasing steadily (1). The three most common treatment modalities, surgery, radiotherapy, and androgen ablation, are all associated with significant side effects and reduced quality of life (2). It is therefore desirable to develop new immunotherapy options with the potential to selectively eliminate prostate cancer cells. CTL are important effectors of antitumor immune responses (3). The vast majority of CTL-recognized targets described to date are tumor-associated antigens such as the Wilms’ tumor antigen (WT1 ), which is currently being evaluated for the immunotherapy of a number of leukemias and solid tumors. WT1 is an oncogene which is overex- pressed in several leukemias and solid tumors including breast, lung, ovarian, and colon cancer (4–8), and WT1 expression levels have been shown to correlate with a poor prognosis in leukemia and breast cancer (9, 10). In addition, blocking the action of WT1 with antisense oligomers prevented tumor cells from proliferating in vitro , suggesting that WT1 may contribute towards maintenance of the malignant phenotype (11, 12). There is currently limited information regarding the expression and immunogenicity of WT1 in prostate cancer. In this study we assessed WT1 expression in prostate cancer tissues, evaluated whether there were measurable WT1 - specific CTL in patients, and whether these CTL were functional in vitro. WT1 immunohistochemistry was done on tissue arrays comprising 36 prostate cancer samples and 8 normal prostate samples, and a human leukocyte antigen (HLA)-A2/pWT126 tetramer was used to quantify WT1 - specific T cells. Whereas 39% of prostate cancer samples showed nuclear WT1 staining, none of the normal prostate tissues showed nuclear staining for WT1 (P = 0.036). Tetramer-binding T cells were detected ex vivo in the peripheral blood of 20 of 38 (53%) patients with prostate cancer. The tetramer-positive T cells did not respond to Human Cancer Biology Authors’Affiliations: Departments of 1 Immunology, 2 Oncology, and 3 Urology, University College London, Royal Free Hospital, and Departments of 4 Histopathology and 5 Oncology, Imperial College London, Hammersmith Hospital, London, United Kingdom; and 6 Anatomia Patologica, Universita’di Foggia, Ospedale D’Avanzo, Foggia, Italy Received7/15/08;revised9/21/08;accepted10/13/08. Grantsupport: DinwoodieTrust,LeukaemiaResearchFundandFP6EU-ATTACK project. Thecostsofpublicationofthisarticleweredefrayedinpartbythepaymentofpage charges.Thisarticlemustthereforebeherebymarked advertisement inaccordance with18U.S.C.Section1734solelytoindicatethisfact. Note: H.J.StaussandJ.Waxmancontributedequallytothiswork. Requestsforreprints: HansJ.Stauss,DepartmentofImmunology,University College London, Royal Free Hospital, Rowland Hill Street, London, NW3 2PF, UnitedKingdom.Phone:44-0-20-7794-0500,ext.33321;Fax:44-0-20-7830- 2224;E-mail:h.stauss@medsch.ucl.ac.uk. F 2009AmericanAssociationforCancerResearch. doi:10.1158/1078-0432.CCR-08-1821 www.aacrjournals.org ClinCancerRes2009;15(4)February15,2009 1145 Downloaded from http://aacrjournals.org/clincancerres/article-pdf/15/4/1145/1987302/1145.pdf by guest on 14 June 2022