Immunotherapy by CD40 stimulation and IL-2 against Cancer

晚期癌症患者的治疗选择严重受限。选择性免疫攻击是对抗播散性疾病的一种手段。CD40-CD40L相互作用已被证明是产生最佳免疫应答的关键。我们最近证明，在患有晚期转移性肾细胞癌（RCC）和其他实体瘤的小鼠中，使用一种激动剂抗体联合il - 2刺激CD40可以产生高度协同的抗肿瘤反应。仅使用该组合即可获得显著的保护。这种保护作用与树突状细胞和肿瘤特异性CD8+ T细胞数量的显著增加有关，并且令人惊讶的是，与CD4+ T细胞反应无关。我们现在建议描述这些协同抗肿瘤反应的机制并对其进行优化。为实现这一目标，我们制定了三个具体目标。特异性靶1将确定CD40刺激对肿瘤本身的影响。虽然CD40刺激已被证明可诱导多种B细胞淋巴瘤的活化诱导细胞死亡（AICD），但其对实体瘤的影响仍存在争议，且尚不清楚。初步数据表明，CD40刺激确实可以诱导RCC系的AICD，重要的是，可能增加肿瘤对免疫介导攻击的易感性。将在细胞和分子水平上评估CD40刺激的效果。特异性目标2将研究为什么在联合治疗后没有CD4+ T细胞参与的机制，以及这如何损害持续的抗肿瘤反应。初步数据表明，由于干扰素γ导致二次反应受损，CD4+ T细胞在联合治疗后发生AICD。预防这种CD4+ T细胞损失的方法及其对抗肿瘤反应的后续影响将被研究。最后，特异性Aim 3将在晚期荷瘤小鼠中确定肿瘤疫苗和去除抑制影响（如调节性T细胞）的功效。初步数据表明，在抗cd40和IL-2治疗时使用肿瘤疫苗可大大提高疗效，从而实现长期治愈。这一建议不仅对IL-2刺激CD40的临床外推，而且对一般免疫调节和肿瘤反应都有重要意义。

Treatment options for patients with advanced cancer are seriously limited. Selective immune attack provides a means to combat disseminated disease. CD40-CD40L interactions have been demonstrated to be critical in the generation of optimal immune responses. We have recently demonstrated that CD40 stimulation using an agonist antibody combined with IL2 can result in highly synergistic anti-tumor responses in mice bearing advanced metastatic renal cell carcinomas (RCC) and other solid tumors. Significant protection occurred using the combination only. This protection was correlated with significant increases in dendritic cell and tumor-specific CD8+ T cell numbers and surprisingly, independent of CD4+ T cell responses. We now propose to delineate the mechanisms underlying these synergistic anti-tumor responses and optimize them. Toward this goal we have developed three specific aims. Specific Aim 1 will determine the effects of CD40 stimulation on the tumor itself. While CD40 stimulation has been shown to induce activation-induced cell death (AICD) on a variety of B cell lymphomas, the effect on solid tumors is controversial and much less clear. Preliminary data indicate that CD40 stimulation can indeed induce AICD in RCC lines and importantly, may increase susceptibility of the tumor to immune-mediated attack. Assessment of the effects of CD40 stimulation at both cellular and molecular levels will be performed. Specific Aim 2 will examine the mechanisms as to why there is no engagement of CD4+ T cells after combination treatment and how this may impair sustained anti- tumor responses. Preliminary data suggest that the CD4+ T cell undergo AICD after combination treatment due to interferon-gamma resulting in impaired secondary responses. Means to prevent this CD4+ T cell loss with subsequent effects on anti-tumor responses will be examined. Finally, Specific Aim 3 will determine the efficacy of tumor vaccines and removal of inhibitory influences such as regulatory T cells in advanced tumor-bearing mice. Preliminary data indicates that use of tumor vaccines at the time of anti-CD40 and IL-2 treatment greatly augments efficacy resulting in long-term cures. This proposal should yield significant insights, not only in the clinical extrapolation of CD40 stimulation with IL-2, but also in general immune regulation and tumor responses.