在癌症免疫治疗领域，经过工程改造的基于细胞因子的方法即将进入临床试验阶段，其中IL-12处于前沿。然而，对于细胞因子治疗的潜在耐药机制了解甚少。我们发现，原位移植的小鼠肺肿瘤对系统性给予的小鼠血清白蛋白(IL12-MSA)融合IL-12抗体疗法具有耐药性，原因是肿瘤反应性CD8+T细胞的IL-12R表达较低。IL2-MSA增加了肿瘤反应性CD8+T细胞对IL12-MSA的结合，同时给予IL12-MSA和IL2-MSA联合治疗，导致肺肿瘤反应性CD8+T细胞效应分化增强、肿瘤内CD4+调节性T细胞数量减少和肺肿瘤患者存活时间延长。可预见的是，治疗剂量下的IL-2和IL-12联合会引起显著的剂量限制性毒性反应。给予与IL12rb1和CD25表达阳性细胞优先结合的IL-12和IL-2类似物，可显著延长肺肿瘤小鼠的存活时间，同时消除剂量限制性毒性反应。这些发现表明，IL-12和IL-2的联合细胞因子疗法是一种合理的方法，其剂量限制性毒性可以通过工程改造的细胞因子变体来克服。

Engineered cytokine-based approaches for immunotherapy of cancer are poised to enter the clinic, with IL-12 being at the forefront. However, little is known about potential mechanisms of resistance to cytokine therapies. We found that orthotopic murine lung tumors were resistant to systemically delivered IL-12 fused to murine serum albumin (MSA, IL12-MSA) due to low IL-12R expression on tumor-reactive CD8+ T cells. IL2-MSA increased binding of IL12-MSA by tumor-reactive CD8+ T cells, and combined administration of IL12-MSA and IL2-MSA led to enhanced tumor-reactive CD8+ T cell effector differentiation, decreased numbers of tumor-infiltrating CD4+ regulatory T (Treg) cells, and increased survival of lung tumor-bearing mice. Predictably, the combination of IL-2 and IL-12 at therapeutic doses led to significant dose-limiting toxicity. Administering IL-12 and IL-2 analogs with preferential binding to cells expressing IL12rb1 and CD25, respectively, led to a significant extension of survival in mice with lung tumors while abrogating dose-limiting toxicity. These findings suggest that IL-12 and IL-2 represent a rational approach to combination cytokine therapy whose dose-limiting toxicity can be overcome with engineered cytokine variants.