Neratinib augments the lethality of [regorafenib + sildenafil]

Abstract

Regorafenib is approved for the treatment of colorectal cancer and hepatocellular carcinoma. In the trial NCT02466802, we have discovered that regorafenib can be safely combined with the phosphodiesterase 5 inhibitor sildenafil in advanced solid tumor patients. The present studies determined whether the approved ERBB1/2/4 and RAS downregulating drug neratinib, could enhance the lethality of [regorafenib + sildenafil]. Neratinib enhanced [regorafenib + sildenafil] lethality in a greater than additive fashion in colon cancer cells. The drug combination reduced the expression of mutant K-RAS and of multiple histone deacetylase (HDAC) proteins that required autophagosome formation. It caused green fluorescent protein or red fluorescent protein-tagged forms of K-RAS V12 to localize into large intracellular vesicles. Compared with [regorafenib + sildenafil], the three-drug combination caused greater and more prolonged activation of the ATM-AMPK-ULK-1 pathway and caused a greater suppression and prolonged inactivation of mammalian target of rapamycin, AKT, and p70 S6K. Approximately 70% of enhanced lethality caused by neratinib required ataxia-telangiectasia-mutated (ATM)-AMP-dependent protein kinase (AMPK) signaling whereas knockdown of Beclin1, ATG5, FADD, and CD95 completely prevented the elevated killing effect. Exposure of cells to [regorafenib + sildenafil] reduced the expression of the checkpoint immunotherapy biomarkers programmed death-ligand 1, ornithine decarboxylase, and indoleamine 2,3-dioxygenase-1 and increased the expression of major histocompatibility complex A (MHCA), which also required autophagosome formation. Knockdown of specific HDAC proteins recapitulated the effects observed using chemical agents. In vivo, using mouse cancer models, neratinib significantly enhanced the antitumor efficacy of [regorafenib + sildenafil]. Our data support performing a new three drug Phase I trial combining regorafenib, sildenafil, and neratinib.

GZ17‐6.02 initiates DNA damage causing autophagosome‐dependent HDAC degradation resulting in enhanced anti‐PD1 checkpoint inhibitory antibody efficacy

“…The reasoning behind the combination of 602 with 5FU in our in vitro laboratory‐based studies was in part predicated on these prior studies. In the case of curcumin, alone or combined with sildenafil, the roles of reactive oxygen (and nitrogen) species in the killing process were defined, with death receptor signaling, autophagy, and mitochondrial dysfunction all playing a role in the death processes (Booth, Roberts, Sander, et al, 2019; Booth, Roberts, Rais, et al, 2019). A modest portion of 602 lethalities is also mediated by death receptor signaling.…”

Therapeutic targeting of 3′,5′-cyclic nucleotide phosphodiesterases: inhibition and beyond

“…As described for PDE4i's, a number of trials are exploring the therapeutic potential of PDE5i's as chemopreventives for solid tumors, multiple myeloma, and head and neck squamous cell carcinoma. Early reports suggest combining sildenafil with the chemotherapeutic regorafenib is safe in patients with solid tumors (165). Further, a number of in vitro and animal models of colorectal cancer suggest that PDE5i's, either alone or as part of a multi-chemotherapeutic regimen, demonstrate an ability to prevent tumor growth (e.g., (24,165,166)).…”

“…Early reports suggest combining sildenafil with the chemotherapeutic regorafenib is safe in patients with solid tumors (165). Further, a number of in vitro and animal models of colorectal cancer suggest that PDE5i's, either alone or as part of a multi-chemotherapeutic regimen, demonstrate an ability to prevent tumor growth (e.g., (24,165,166)). Similarly, reports from both retrospective and prospective trials suggest tadalafil promotes tumor immunity in patients with head and neck squamous cell carcinoma (Table 3,…”

Neratinib degrades MST4 via autophagy that reduces membrane stiffness and is essential for the inactivation of PI3K, ERK1/2, and YAP/TAZ signaling

“…was also changing the morphology of pancreatic cancer cells (Figures S5-S7)(Booth, Roberts, Rais et al, 2019;Dent, Booth, Roberts et al, 2019). Similar findings were then observed in a PDX isolate ofpancreatic cancer and an established GEMM tumor cell isolate (Figures S6 and S7).…”