Phase I study of envafolimab (KN035), a novel subcutaneous single-domain anti-PD-L1 monoclonal antibody, in Japanese patients with advanced solid tumors.

Envafolimab is the first and only globally approved subcutaneously injectable PD-L1 antibody. This open-label, multicenter Phase 1 trial assessed the safety, tolerability, pharmacokinetic (PK) profile, and efficacy of envafolimab as a single agent in Japanese patients with advanced solid tumors. In the dose-escalation phase, 10 patients received subcutaneous (SC) envafolimab QW at 1.0 mg/kg, 2.5 mg/kg and 5.0 mg/kg. In the dose-expansion phase, 16 patients were treated at 2.5 or 5.0 mg/kg Q2W in part-1 and 9 patients received SC envafolimab 300 mg Q4W in part-2. No dose-limiting toxicities (DLTs) were reported. Envafolimab was well tolerated and no new safety signals were identified compared with other marketed products of the same class. Three patients reported Grade ≥ 3 envafolimab-related treatment-emergent adverse events (TEAE), including adrenal insufficiency, cerebral infarction, and immune-mediated enterocolitis. Envafolimab demonstrated dose-proportional increases in area under the time-concentration curve (AUC) and maximum serum concentration (Cmax). The overall response rate (ORR) was 11.4% (n = 4) and disease control rate (DCR) was 34.3% (n = 12). Consistent with that observed in other envafolimab Phase 1 trials and approved PD-1/PD-L1 inhibitors, the safety profile of SC envafolimab in Japanese patients with advanced solid tumors was well tolerated with efficacy comparable to IV administered treatments. Pharmacokinetics data and preliminary anti-tumor response support dose regimens with longer dosing intervals (Q2W or Q4W). As such, envafolimab offers patients a more convenient treatment option than currently available intravenously administered PD-1/PD-L1 inhibitors. CLINICALTRIALS.GOV IDENTIFIER: NCT03248843(August 14, 2017).

Subcutaneous envafolimab monotherapy in patients with advanced defective mismatch repair/microsatellite instability high solid tumors.

BACKGROUND: Monoclonal antibodies targeting programmed death ligand 1 (PD-L1) signaling currently approved for defective mismatch repair (dMMR)/microsatellite instability high (MSI-H) tumors must be delivered by intravenous infusion. Envafolimab, a humanized single-domain anti-PD-L1 antibody fused to an Fc fragment, represents a potential advance because it can be conveniently administered subcutaneously. METHODS: This open-label, single-arm, phase 2 study evaluated the efficacy and safety of envafolimab in patients with previously treated advanced dMMR/MSI-H tumors from 25 clinical sites across China. Adults with histologically confirmed locally advanced or metastatic malignant dMMR/MSI-H solid tumors received weekly 150 mg subcutaneous envafolimab injections in a 28-day treatment cycle. The primary efficacy endpoint was the objective response rate (assessed by a blinded independent review committee). Secondary efficacy outcomes were disease control rate, duration of response, progression-free survival, and overall survival. RESULTS: One hundred and three patients (65 with colorectal cancer, 18 with gastric cancer, and 20 with other solid tumors) were enrolled. Median follow-up was 11.5 months. The objective response rate was 42.7% (95% confidence interval [CI] 33.0-52.8), and the disease control rate was 66.0% (95% CI 56.0-75.1). Median duration of response was not reached; the duration of response rate at 12 months was 92.2% (95% CI 77.5-97.4). Median progression-free survival was 11.1 months (95% CI 5.5 to not evaluable). Overall survival at 12 months was 74.6% (95% CI 64.7-82.1). Sixteen patients (16%) had at least one grade 3 or 4 related treatment-emergent adverse event. No grade 5 treatment-emergent adverse events related to envafolimab were reported. Injection site reactions, all grade 1-2, were reported in nine patients (9%), but there were no infusion reactions. Eight patients (8%) had grade 3 or 4 immune-related adverse events. CONCLUSIONS: This is the first pivotal phase 2 study to examine the efficacy and safety of a single-domain immune checkpoint antibody in the treatment of cancer. Envafolimab was effective and had acceptable safety in the treatment of previously treated advanced dMMR/MSI-H solid tumors. As the first single-domain PD-L1-targeting antibody administered by rapid subcutaneous injection, envafolimab has the potential to be a significant advance in the treatment of cancer. Trial registration ClinicalTrials.gov, NCT03667170. Registered 10 September 2018-Retrospectively registered, https://clinicaltrials.gov/ct2/show/NCT03667170 .

Construction and characterization of an infectious replication competent clone of porcine endogenous retrovirus from Chinese miniature pigs.

BACKGROUND: Xenotransplantation from animals has been considered to be a preferable approach to alleviate the shortage of human allografts. Pigs are the most suitable candidate because of the anatomical and physiological similarities shared with humans as well as ethical concerns. However, it may be associated with the risk of transmission of infectious porcine pathogens. Porcine endogenous retroviruses (PERVs) are of particular concern because they have been shown to infect human cells in vitro. To date, researches on the molecular characteristics and potential pathogenicity of PERV are still tenuous. In this report, an infectious replication competent clone of PERV from Wuzhishan pigs (WZSPs) in China was generated and characterized. This infectious clone will contribute to studies on PERV virology and control of PERV in xenotransplantation using Chinese miniature pigs. METHODS: The proviral DNA of PERV from WZSPs was amplified in two overlapping halves. Then the two fragments were isolated, subcloned and fused to generate pBluescriptαSK+-WZS-PERV recombinant clones. Screened with RT-PCR, a molecular clone of PERV designated as WZS-PERV(2) was selected. Its infectivity and replication competency were characterized in HEK293 cells by PCR, real-time fluorescent quantitative RT-PCR, western blot, indirect immunofluorescence assay as well as sequence analysis. RESULTS: The ability of WZS-PERV(2) to infect human cells and produce infectious virions were shown after transfection of the clone into HEK293 cells and infection of PERV derived from this recombinant clone. The expression of Gag proteins were detected in HEK293 cells infected with the virus derived from the clone by the indirect immunofluorescence assay and western blot. The results of sequences analysis and comparison combined with the PCR based genotyping result demonstrated that the WZS-PERV(2) belonged to PERV-A subgroup. Compared with a previous proviral DNA clone of PERV (PERV-WZSP), G to A hypermutation occurred in the env gene of WZS-PERV(2) was found, whereas APOBEC proteins have the potential to inhibit the replication of a variety of retroviruses through a cDNA cytosine deamination mechanism, so we presumed these G to A hypermutation might be the contribution of porcine APOBEC3F. CONCLUSIONS: Altogether, an infectious replication competent clone of PERV from Chinese miniature pigs (WZSPs) termed WZS-PERV(2) was generated, characterized and sequenced.