1060 DF9001, an EGFR targeted immune engager, stimulates innate and adaptive anti-tumor immunity with a distinctive safety profile

<h3>Background</h3> Epidermal growth factor receptor (EGFR) is expressed at high levels across solid cancers. While EGFR antagonists have shown activity against EGFR-driven cancers, all are accompanied by significant toxicities, and tumors become resistant resulting in disease relapse. The broad expression of EGFR in normal tissues has been a barrier to the development of EGFR-targeted antibody-drug conjugates, T cell engagers, and chimeric antigen receptor T cells. DF9001 is an immune modulating TriNKET^® with a distinctive safety profile that consists of an EGFR-targeting scFv, a human IgG1 Fc domain, and a Fab that agonizes NKG2D, an activating receptor expressed by NK cells, CD8⁺ T cells, and γδ T cells. <h3>Methods</h3> DF9001 was characterized using human primary cell subsets and cell lines. The ability of DF9001 to inhibit EGFR signaling and to drive immune-mediated responses was assessed in vitro using co-culture assays. The anti-tumor efficacy of DF9001 and a mouse surrogate TriNKET^® were tested in xenograft and syngeneic mouse models, respectively. DF9001 was also evaluated in non-human primate (NHP) studies. <h3>Results</h3> DF9001 bound strongly to EGFR⁺ tumor cells and directly inhibited growth of tumor cell lines that express wild-type EGFR and KRAS. DF9001 stimulated potent NK cell-mediated lysis of EGFR⁺ tumor cells including those less susceptible to approved EGFR-targeting antibody cetuximab (e.g., harboring EGFR or KRAS mutations). DF9001 induced the release of cytokines and chemokines from NK cells, which recruited additional immune effector cells including CD8⁺ T cells. DF9001 also redirected macrophages and activated CD8⁺ T cells to efficiently target EGFR⁺ tumor cells. In mouse models, DF9001 or a mouse surrogate TriNKET^® showed potent anti-tumor efficacy driven by both EGFR signal inhibition as well as immune modulation. In NHP studies, DF9001 had a manageable safety profile consistent with EGFR blockade and notably a lack of immune reactivity against healthy EGFR-expressing tissues. <h3>Conclusions</h3> DF9001 disrupts tumor growth by inhibiting EGFR signaling and promoting anti-tumor immunity. DF9001 has been optimized for engagement of immune cell populations that lead to the direct killing of tumor cells, while sparing healthy tissues, as well as the production of chemokines and cytokines that recruit additional effector cells to kill tumor cells. These characteristics make DF9001 a promising therapeutic candidate against EGFR⁺ cancers, particularly those for which EGFR signal inhibition alone is ineffective. DF9001 is currently being evaluated in a PhI/Ib clinical trial in patients with EGFR-expressing advanced solid tumors (NCT05597839).