Pancreatic ductal adenocarcinoma (PDAC) is considered the third leading cause of cancer mortality in the western world, offering advanced stage patients with few viable treatment options. Consequently, there remains an urgent unmet need to develop novel therapeutic strategies that can effectively inhibit pro-oncogenic molecular targets underpinning PDACs pathogenesis and progression. One such target is c-RAF, a downstream effector of RAS that is considered essential for the oncogenic growth and survival of mutant RAS-driven cancers (including KRAS^MT PDAC). Herein, we demonstrate how a novel cell-penetrating peptide disruptor (DRx-170) of the c-RAF–PDE8A protein–protein interaction (PPI) represents a differentiated approach to exploiting the c-RAF–cAMP/PKA signaling axes and treating KRAS–c-RAF dependent PDAC. Through disrupting the c-RAF–PDE8A protein complex, DRx-170 promotes the inactivation of c-RAF through an allosteric mechanism, dependent upon inactivating PKA phosphorylation. DRx-170 inhibits cell proliferation, adhesion and migration of a KRAS^MT PDAC cell line (PANC1), independent of ERK1/2 activity. Moreover, combining DRx-170 with afatinib significantly enhances PANC1 growth inhibition in both 2D and 3D cellular models. DRx-170 sensitivity appears to correlate with c-RAF dependency. This proof-of-concept study supports the development of DRx-170 as a novel and differentiated strategy for targeting c-RAF activity in KRAS–c-RAF dependent PDAC.

胰腺导管腺癌 (PDAC) 被认为是西方世界癌症死亡的第三大原因，为晚期患者提供了几乎没有可行的治疗选择。因此，仍然迫切需要开发新的治疗策略，以有效抑制支持 PDAC 发病机制和进展的促癌分子靶点。其中一个靶点是 c-RAF，它是 RAS 的下游效应子，被认为对于突变 RAS 驱动的癌症（包括 KRAS ^MT PDAC）的致癌生长和生存至关重要。在此，我们展示了 c-RAF-PDE8A 蛋白-蛋白相互作用 (PPI) 的新型细胞穿透肽干扰剂 (DRx-170) 如何代表一种利用 c-RAF-cAMP/PKA 信号轴和治疗 KRAS 的差异化方法–c-RAF 依赖的 PDAC。通过破坏 c-RAF-PDE8A 蛋白复合物，DRx-170 通过变构机制（依赖于失活的 PKA 磷酸化）促进 c-RAF 失活。 DRx-170 抑制 KRAS ^MT PDAC 细胞系 (PANC1) 的细胞增殖、粘附和迁移，与 ERK1/2 活性无关。此外，将 DRx-170 与阿法替尼联合使用可显着增强 2D 和 3D 细胞模型中 PANC1 的生长抑制。 DRx-170 敏感性似乎与 c-RAF 依赖性相关。这项概念验证研究支持将 DRx-170 开发为一种新颖的差异化策略，用于靶向 KRAS-c-RAF 依赖性 PDAC 中的 c-RAF 活性。