INBRX-120, a CD8α-targeted detuned IL-2 that selectively expands and activates tumoricidal effector cells for safe and durable in vivo responses.

BACKGROUND: As a major driver of lymphocyte proliferation and activation interleukin 2 (IL-2) is a crucial mediator for antitumor responses. Despite promising activity in a subset of patients, wider therapeutic utility of IL-2 (aldesleukin) has been hampered by severe dose-limiting toxicities, the expansion of immunosuppressive regulatory T cells and a poor pharmacokinetic (PK) profile. Recent engineering efforts, including non-α IL-2 variants, have lowered the toxicity profile, but have yet to induce meaningful antitumor activity in a wider patient population. METHODS: We engineered INBRX-120, a CD8α-targeted Cisleukin™ molecule consisting of an affinity tuned IL-2 (IL2-x) connected to two high affinity CD8α-specific single domain antibodies via an effector-silenced Fc domain. To show that this large affinity differential enables directed IL-2 cis-signaling exclusively on CD8α-expressing tumoricidal effector cell populations, INBRX-120 effects on target cell expansion, activation and antitumor activity were tested in vitro. In vivo antitumor efficacy was evaluated in syngeneic mouse models alone or in combination with programmed cell death protein-1 (PD-1) blockade. Preclinical safety, as well as pharmacodynamic (PD) and PK profiling was carried out in non-human primates. RESULTS: INBRX-120 effectively expanded and enhanced the cytotoxic capacity of CD8 T cells and natural killer cells towards tumor cells without affecting regulatory T cells in vitro and in vivo. In syngeneic mouse models, INBRX-120 surrogate showed safe, potent, and durable antitumor efficacy alone and in combination with PD-1 blockade. In non-human primates, INBRX-120 expanded and activated CD8α-expressing effector cells, showed a favorable PK profile, and was well tolerated up to a dose of 1 mg/kg. CONCLUSIONS: Through its unique cis-signaling activity on CD8α-expressing effector cells, INBRX-120 overcomes the major limitations of IL-2-based therapy and effectively harnesses IL-2's potent intrinsic antitumor activity. This novel therapeutic strategy promises safer clinical activity that could induce meaningful antitumor efficacy in a wider set of patients with various cancer indications.

Spatial regulation of gene expression in nonsyndromic sagittal craniosynostosis.

OBJECTIVECranial suture patterning and development are highly regulated processes that are not entirely understood. While studies have investigated the differential gene expression for different sutures, little is known about gene expression changes during suture fusion. The aim of this study was to examine gene expression in patent, fusing, and fused regions along sagittal suture specimens in nonsyndromic craniosynostosis patients.METHODSSagittal sutures were collected from 7 patients (average age 4.5 months) who underwent minimally invasive craniotomies at the Children's Hospital of Richmond at VCU under IRB approval. The sutures were analyzed using micro-CT to evaluate patency. The areas were classified as open, fusing, or fused and were harvested, and mRNA was isolated. Gene expression for bone-related proteins, osteogenic and angiogenic factors, transforming growth factor-ß (TGF-ß) superfamily, and Wnt signaling was analyzed using quantitative polymerase chain reaction and compared with normal sutures collected from fetal demise tissue (control).RESULTSMicro-CT demonstrated that there are variable areas of closure along the length of the sagittal suture. When comparing control samples to surgical samples, there was a significant difference in genes for Wnt signaling, TGF-ß, angiogenic and osteogenic factors, bone remodeling, and nuclear rigidity in mRNA isolated from the fusing and fused areas of the sagittal suture compared with patent areas (p < 0.05).CONCLUSIONSIn nonsyndromic sagittal craniosynostosis, the affected suture has variable areas of being open, fusing, and fused. These specific areas have different mRNA expression. The results suggest that BMP-2, FGFR3, and several other signaling pathways play a significant role in the regulation of suture fusion as well as in the maintenance of patency in the normal suture.