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方法: 患者は12人、HLA-A*0201陽性で進行性悪性黒色腫を発症。これらの患者にG280-9Vをパルスした樹状細胞を投与した。樹状細胞はそれぞれ5X106個(3人)、15X106個(3人)、50X106個(6人)を3週間毎に計6回静脈投与した。今回サイトカインの追加投与は行われなかった。G280-9Vをパルスした樹状細胞の免疫活性はELISPOT, テトラマー試験、51Cr遊離試験により樹状細胞投与前後で比較した。今回の治療は固形癌における反応評価基準に従い評価した。
主な結果: CD8+のG280に対する免疫活性はELISPOTにより8人(67%)、テトラマー試験により12人(100%)で観察された。またHLA-A*0201とgp100を共発現するメラノーマ細胞を使用したCTL活性試験は、試験を行った9人のうち9人(100%)にCTLの強い活性が認められた。平均の経過観察時間は43.8ヶ月であった。2人(17%)に部分反応(PR)、3人(25%)に増殖停止(SD)が観察された。平均生存時間は37.6ヶ月で現在3人の患者が生存しており、そのうち一人は追加治療を行わずに免疫反応が継続している。
結論: 今回の高頻度での免疫活性および臨床的な腫瘍退縮の発現はG280-9Vをメラノーマワクチンのエピトープの候補として支持する結果である。
Immunization using autologous dendritic cells pulsed with the melanoma-associated antigen gp100-derived G280-9V peptide elicits CD8+ immunity.
Linette GP et. al.,
Clin Cancer Res. 2005 Nov 1;11(21):7692-9.
PURPOSE: To determine the toxicity, maximal tolerated dose, and clinical and immunologic response to autologous dendritic cells pulsed with melanoma-associated antigen gp100-derived G280-9V peptide. PATIENTS AND METHODS: Twelve HLA-A*0201(+) patients with advanced melanoma were administered dendritic cells pulsed with G280-9V peptide. Cohorts of three patients were administered 5 x 10(6), 15 x 10(6), and 50 x 10(6) cells i.v. every 3 weeks for six doses according to a dose escalation scheme. Three additional patients were treated at the highest dose. No additional cytokines or therapies were coadministered. The immunogenicity of G280-9V-pulsed dendritic cells was measured by IFN-gamma ELISPOT assay, tetramer assay, and (51)Cr release assay comparing prevaccination to postvaccination blood samples. Response to treatment was assessed by Response Evaluation Criteria in Solid Tumors. RESULTS: CD8(+) immunity to the native G280 was observed in 8 (67%) patients as measured by ELISPOT and in 12 (100%) patients as measured by tetramer assay. Of the 9 patients tested, 9 (100%) had measurable high-avidity CTL activity as defined by lysis of allogeneic melanoma lines, which coexpress HLA-A*0201 and gp100. The median follow-up of the entire cohort is 43.8 months. Two (17%) partial responses were observed and 3 (25%) patients had stable disease. The median survival of the treated population was 37.6 months. At this time, three patients are alive, including one patient who continues to respond without additional treatment. CONCLUSION: The high rate of immunization as measured by three independent assays and the occurrence of clinical regression support continued investigation of G280-9V peptide as a candidate epitope in melanoma vaccine formulations.