No abstract

KRASG12C has emerged as a promising target in the treatment of solid tumors. Covalent inhibitors targeting the mutant cysteine-12 residue have been shown to disrupt signaling by this long-“undruggable” target; however clinically viable inhibitors have yet to be identified. Here, we report efforts to exploit a cryptic pocket (H95/Y96/Q99) we identified in KRASG12C to identify inhibitors suitable for clinical development. Structure-based design efforts leading to the identification of a novel quinazolinone scaffold are described, along with optimization efforts that overcame a configurational stability issue arising from restricted rotation about an axially chiral biaryl bond. Biopharmaceutical optimization of the resulting leads culminated in the identification of AMG 510, a highly potent, selective, and well-tolerated KRASG12C inhibitor currently in phase I clinical trials (NCT03600883).

c-Met is a well-characterized receptor tyrosine kinase for hepatocyte growth factor (HGF). Compelling evidence from studies in human tumors and both cellular and animal tumor models indicates that signaling through the HGF/c-Met pathway mediates a plethora of normal cellular activities, including proliferation, survival, migration, and invasion, that are at the root of cancer cell dysregulation, tumorigenesis, and tumor metastasis. Inhibiting HGF-mediated signaling may provide a novel therapeutic approach for treating patients with a broad spectrum of human tumors. Toward this goal, we generated and characterized five different fully human monoclonal antibodies that bound to and neutralized human HGF. Antibodies with subnanomolar affinities for HGF blocked binding of human HGF to c-Met and inhibited HGF-mediated c-Met phosphorylation, cell proliferation, survival, and invasion. Using a series of human-mouse chimeric HGF proteins, we showed that the neutralizing antibodies bind to a unique epitope in the B-chain of human HGF. Importantly, these antibodies inhibited HGF-dependent autocrine-driven tumor growth and caused significant regression of established U-87 MG tumor xenografts. Treatment with anti-HGF antibody rapidly inhibited tumor cell proliferation and significantly increased the proportion of apoptotic U-87 MG tumor cells in vivo. These results suggest that an antibody to an epitope in the B-chain of HGF has potential as a novel therapeutic agent for treating patients with HGF-dependent tumors.

Several recently reported investigations have shown that a member of the neurotrophin family of neuronal growth factors, brain-derived neurotrophic factor (BDNF), supports motoneurons in vitro and rescues motoneurons from naturally occurring and axotomy-induced cell death (Oppenheim et al., 1992b; Sendtner et al., 1992b; Yan et al., 1992; Koliatsos et al., 1993; Henderson et al., 1993). In the current study, we have explored the issue of whether BDNF and other neurotrophins act to regulate motoneuron survival during development and asked whether synthesis of motoneuron transmitter enzymes is also regulated. We first examined whether spinal motoneurons in newborn animals could retrogradely transport iodinated neurotrophins from their targets in a specific, receptor-mediated manner. We found that motoneurons readily transported NGF, BDNF, and neurotrophin-3 (NT-3). The retrograde transport of one factor could be completely or largely blocked by excess of unlabeled homologous factor, but only partially blocked by excess of unlabeled heterologous factors. Since previous studies have shown that these three neurotrophins bind to the low-affinity NGF receptor, p75NGFR, with similar affinity, our data suggest that the retrograde transport of neurotrophins by motoneurons may be mediated by additional components, such as the trk family of proto-oncogenes. Consistent with this hypothesis, we demonstrate here that motoneurons express mRNA for two members of the trk family, trkB and trkC. Furthermore, both trkB and trkC were expressed by E13, consistent with a role for BDNF and NT-3 in regulating important developmental events involving motoneurons such as naturally occurring cell death. In order to determine which members of the neurotrophin family influence motoneuron survival and to assess the generality of their effects, we evaluated the abilities of NGF, BDNF, and NT-3 to save both spinal and cranial motoneurons after neonatal axotomy. Locally applied BDNF saved 40-70% of motoneurons which would ordinarily die after axotomy in lumbar and cranial motor pools, depending on the treatment protocol employed. NT-3 also exhibited some ability to rescue motoneurons and saved 20-25% of motoneurons which would die in the absence of treatment. Finally, we asked whether neurotrophins could influence synthesis of transmitter enzymes by motoneurons as well as their survival after axotomy. Locally applied BDNF and NT-3 could partially prevent the decrease of protein contents in L4 and L5 ventral roots which normally follows sciatic nerve transection. However, treatment with these neurotrophins did not prevent the decrease in choline acetyltransferase (ChAT) activity in L4 and L5 ventral roots which results from this procedure.(ABSTRACT TRUNCATED AT 400 WORDS)

AMG 386 is an investigational first-in-class peptide-Fc fusion protein (peptibody) that inhibits angiogenesis by preventing the interaction of angiopoietin-1 (Ang1) and Ang2 with their receptor, Tie2. Although the therapeutic value of blocking Ang2 has been shown in several models of tumorigenesis and angiogenesis, the potential benefit of Ang1 antagonism is less clear. To investigate the consequences of Ang1 neutralization, we have developed potent and selective peptibodies that inhibit the interaction between Ang1 and its receptor, Tie2. Although selective Ang1 antagonism has no independent effect in models of angiogenesis-associated diseases (cancer and diabetic retinopathy), it induces ovarian atrophy in normal juvenile rats and inhibits ovarian follicular angiogenesis in a hormone-induced ovulation model. Surprisingly, the activity of Ang1 inhibitors seems to be unmasked in some disease models when combined with Ang2 inhibitors, even in the context of concurrent vascular endothelial growth factor inhibition. Dual inhibition of Ang1 and Ang2 using AMG 386 or a combination of Ang1- and Ang2-selective peptibodies cooperatively suppresses tumor xenograft growth and ovarian follicular angiogenesis; however, Ang1 inhibition fails to augment the suppressive effect of Ang2 inhibition on tumor endothelial cell proliferation, corneal angiogenesis, and oxygen-induced retinal angiogenesis. In no case was Ang1 inhibition shown to (a) confer superior activity to Ang2 inhibition or dual Ang1/2 inhibition or (b) antagonize the efficacy of Ang2 inhibition. These results imply that Ang1 plays a context-dependent role in promoting postnatal angiogenesis and that dual Ang1/2 inhibition is superior to selective Ang2 inhibition for suppression of angiogenesis in some postnatal settings. Mol Cancer Ther; 9(10); 2641–51.