ID: 17: Targeting attenuated cytokines to tumor cells results in robust tumor killing with significantly reduced off-target activity: _Anti-CD38-Attenukine™ _

Many cytokines have potential therapeutic applications and several, including type I interferons (IFN), have been approved for the treatment of cancer and/or autoimmune disease. While these agents are effective, they are associated with dose-limiting toxicities that prevent their use at levels sufficient to promote optimal therapeutic benefit. Thus, approaches which enhance the therapeutic index (TI) of cytokines are needed. A moderate degree of tumor-specificity may be achieved by attaching a cytokine such as IFN to a tumor-targeting antibody; such immunocytokines are highly active but show only moderate tumor-specificity since the cytokine is still active on antigen-negative cells. We sought to improve the TI of antibody-targeted cytokines by mutating the cytokine portion to significantly reduce its affinity for its receptor, thereby making it dependent on antibody-targeting. Here we demonstrate that such molecules, consisting of attenuated cytokines (Attenukines™) attached to tumor-targeting antibodies, are 1000–100,000-fold more potent on antigen-positive cells compared to antigen-negative (normal) cells. This is shown for antibody-Attenukine™ fusion proteins based on multiple tumor antigens (CD20, CD38, CD138, HMW-MAA, HLA) and multiple attenuated mutants of IFN, IFN, IL-4 and IL-6. Furthermore, we have evaluated an anti-CD38-attenuated IFN molecule (anti-CD38-Attenukine™) in various CD38+ myeloma xenograft models and found that this molecule retains potent specific anti-tumor efficacy. Moreover, in non-human primates, we have confirmed that the attenuating mutation in IFN indeed decreases non-targeted IFN biomarker responses by greater than 100-fold. Our findings suggest that the administration of antibody-attenukines™ to cancer patients may promote robust cytokine-dependent tumor-killing while minimizing systemic toxicity.

许多细胞因子具有潜在的治疗应用，包括I型干扰素（IFN）在内的几种细胞因子已被批准用于癌症和/或自身免疫性疾病的治疗。虽然这些药物是有效的，但它们与剂量限制性毒性相关，这使得它们无法在足以促进最佳治疗效果的水平上使用。因此，需要提高细胞因子治疗指数（TI）的方法。通过将一种细胞因子（如干扰素）连接到一种肿瘤靶向抗体上，可以实现一定程度的肿瘤特异性；这种免疫细胞因子具有很高的活性，但仅显示出中等程度的肿瘤特异性，因为细胞因子在抗原阴性细胞上仍然有活性。我们试图通过突变细胞因子部分以显著降低其对受体的亲和力，从而使其依赖于抗体靶向，来提高抗体靶向细胞因子的治疗指数。在此我们证明，由减弱活性的细胞因子（Attenukines™）连接到肿瘤靶向抗体组成的此类分子，在抗原阳性细胞上的效力比在抗原阴性（正常）细胞上高1000 - 100000倍。这在基于多种肿瘤抗原（CD20、CD38、CD138、高分子量黑色素瘤相关抗原、人类白细胞抗原）以及干扰素、干扰素、白细胞介素 - 4和白细胞介素 - 6的多种减弱活性突变体的抗体 - Attenukine™融合蛋白中得到了证实。此外，我们在各种CD38⁺骨髓瘤异种移植模型中评估了一种抗 - CD38减弱活性的干扰素分子（抗 - CD38 - Attenukine™），发现该分子保留了强大的特异性抗肿瘤功效。而且，在非人灵长类动物中，我们已经证实干扰素中的减弱活性突变确实使非靶向干扰素生物标志物反应降低了100倍以上。我们的研究结果表明，给癌症患者施用抗体 - Attenukines™可能会促进强大的细胞因子依赖性肿瘤杀伤，同时将全身毒性降至最低。