First-In-Human, First-In-Class, Phase I Trial of the Fucosylation Inhibitor SGN-2FF in Patients with Advanced Solid Tumors.

LESSONS LEARNED: Inhibition of glycoprotein fucosylation, as monotherapy and in combination with immune checkpoint blockade, is a promising therapeutic strategy for treating a broad range of cancers. In this first-in-human, first-in-class, phase I study in advanced solid tumors, SGN-2FF demonstrated dose-proportional pharmacokinetics, evidence of pharmacodynamic target inhibition of glycoprotein fucosylation, and preliminary antitumor activity. SGN-2FF was associated with thromboembolic events that led to study termination. BACKGROUND: We conducted a first-in-human, first-in-class, phase I study of SGN-2FF, a potent small-molecule inhibitor of glycoprotein fucosylation, in patients with advanced solid tumors. METHODS: The study consisted of four parts: SGN-2FF monotherapy dose-escalation (part A) and expansion (part B), and SGN-2FF + pembrolizumab dose-escalation (part C) and expansion (part D). The objectives were to evaluate safety and tolerability, maximum tolerated dose (MTD), pharmacokinetics (PK), pharmacodynamics (PD), and antitumor activity of SGN-2FF monotherapy and SGN-2FF + pembrolizumab. RESULTS: Forty-six patients were enrolled (part A, n = 33; part B, n = 6; part C, n = 7; part D did not enroll any patients). During part A (n = 32) exploring 1-15 g once daily (QD) and 2-5 g twice daily (b.i.d.), grade 3 dose-limiting toxicities were diarrhea (2 g and 15 g QD) and increased lipase (2 g QD). The MTD was 10 g daily. In part A, common toxicities were grades 1-2 diarrhea, fatigue, and nausea (each 47%); thromboembolic events (grades 2-5) occurred in 5 of 32 patients (16%). Safety measures included concurrent prophylactic anticoagulation with low-molecular weight heparin (LMWH). In part C, despite the safety measures implemented, a thromboembolic event occurred in one of seven patients (14%) during the SGN-2FF lead-in period. Of 28 evaluable patients in part A, 1 patient with advanced head and neck squamous cell carcinoma achieved Response Evaluation Criteria in Solid Tumors (RECIST) v1.1 complete response (CR) and 10 (36%) had RECIST v1.1 stable disease, including 1 patient with advanced triple-negative breast cancer with 51% tumor burden reduction. SGN-2FF administration led to dose-proportional increases in exposure and PD reduction in protein fucosylation. CONCLUSION: SGN-2FF demonstrated proof-of-mechanism and preliminary antitumor activity but was associated with thromboembolic events leading to study termination.

Dose dependent pharmacokinetics, tissue distribution, and anti-tumor efficacy of a humanized monoclonal antibody against DLL4 in mice.

Delta-like-4 ligand (DLL4) plays an important role in vascular development and is widely expressed on the vasculature of normal and tumor tissues. Anti-DLL4 is a humanized IgG1 monoclonal antibody against DLL4. The purpose of these studies was to characterize the pharmacokinetics (PK), tissue distribution, and anti-tumor efficacy of anti-DLL4 in mice over a range of doses. PK and tissue distribution of anti-DLL4 were determined in athymic nude mice after administration of single intravenous (IV) doses. In the tissue distribution study, radiolabeled anti-DLL4 (mixture of (125)Iodide and (111)Indium) was administered in the presence of increasing amounts of unlabeled anti-DLL4. Dose ranging anti-DLL4 anti-tumor efficacy was evaluated in athymic nude mice bearing MV522 human lung tumor xenografts. Anti-DLL4 had nonlinear PK in mice with rapid serum clearance at low doses and slower clearance at higher doses suggesting the involvement of target mediated clearance. Consistent with the PK data, anti-DLL4 was shown to specifically distribute to several normal tissues known to express DLL4 including the lung and liver. Maximal efficacy in the xenograft model was seen at doses ≥ 10 mg/kg when tissue sinks were presumably saturated, consistent with the PK and tissue distribution profiles. These findings highlight the importance of mechanistic understanding of antibody disposition to enable dosing strategies for maximizing efficacy.

Complement inhibition in cynomolgus monkeys by anti-factor d antigen-binding fragment for the treatment of an advanced form of dry age-related macular degeneration.

Anti-factor D (AFD; FCFD4514S, lampalizumab) is a humanized IgG Fab fragment directed against factor D (fD), a rate-limiting serine protease in the alternative complement pathway (AP). Evaluation of AFD as a potential intravitreal (IVT) therapeutic for dry age-related macular degeneration patients with geographic atrophy (GA) is ongoing. However, it is unclear whether IVT administration of AFD can affect systemic AP activation and potentially compromise host-immune responses. We characterized the pharmacologic properties of AFD and assessed the effects of AFD administered IVT (2 or 20 mg) or intravenous (0.2, 2, or 20 mg) on systemic complement activity in cynomolgus monkeys. For the IVT groups, serum AP activity was reduced for the 20 mg dose group between 2 and 6 hours postinjection. For the intravenous groups, AFD inhibited systemic AP activity for periods of time ranging from 5 minutes (0.2 mg group) to 3 hours (20 mg group). Interestingly, the concentrations of total serum fD increased up to 10-fold relative to predose levels following administration of AFD. Furthermore, AFD was found to inhibit systemic AP activity only when the molar concentration of AFD exceeded that of fD. This occurred in cynomolgus monkeys at serum AFD levels ≥2 µg/ml, a concentration 8-fold greater than the maximum serum concentration observed following a single 10 mg IVT dose in a clinical investigation in patients with GA. Based on these findings, the low levels of serum AFD resulting from IVT administration of a clinically relevant dose are not expected to appreciably affect systemic AP activity.

PlGF blockade does not inhibit angiogenesis during primary tumor growth.

It has been recently reported that treatment with an anti-placenta growth factor (PlGF) antibody inhibits metastasis and primary tumor growth. Here we show that, although anti-PlGF treatment inhibited wound healing, extravasation of B16F10 cells, and growth of a tumor engineered to overexpress the PlGF receptor (VEGFR-1), neutralization of PlGF using four novel blocking antibodies had no significant effect on tumor angiogenesis in 15 models. Also, genetic ablation of the tyrosine kinase domain of VEGFR-1 in the host did not result in growth inhibition of the anti-VEGF-A sensitive or resistant tumors tested. Furthermore, combination of anti-PlGF with anti-VEGF-A antibodies did not result in greater antitumor efficacy than anti-VEGF-A monotherapy. In conclusion, our data argue against an important role of PlGF during primary tumor growth in most models and suggest that clinical evaluation of anti-PlGF antibodies may be challenging.