Efficacy and safety of romiplostim in refractory aplastic anaemia: a Phase II/III, multicentre, open-label study.

A previous dose-finding study has suggested that romiplostim is effective in patients with refractory aplastic anaemia (AA) and 10 µg/kg once weekly was recommended as a starting dose. In this Phase II/III, multicentre, open-label study, romiplostim was administered subcutaneously at a fixed dose of 10 µg/kg once weekly for 4 weeks (weeks 1-4) followed by weekly doses (5, 10, 15 and 20 µg/kg) titrated by platelet response for up to 52 weeks (weeks 5-52). A total of 31 patients with AA who were refractory to immunosuppressive therapy (IST) and thrombocytopenia (platelet count of ≤30 × 109 /l) were enrolled. The primary efficacy endpoint of the proportion of patients achieving any haematological (platelet, neutrophil and erythrocyte) response at week 27 was 84% [95% confidence interval (CI) 66-95%]. Trilineage response was 39% (95% CI 22-58%) at week 53. The most common treatment-related adverse events (AEs) were headache and muscle spasms (each 13%). All AEs were mild or moderate except for three patients with Grade 3 hepatic AEs; no AEs necessitated romiplostim discontinuation. Two patients developed cytogenetic abnormalities, of whom one returned to normal karyotype at last follow-up. High-dose romiplostim is effective and well tolerated in the treatment of patients with AA refractory to IST.

TRF2 recruits ORC through TRFH domain dimerization.

Telomeres are specialized chromatin structures that prevent the degradation and instability of the ends of linear chromosomes. While telomerase maintains long stretches of the telomeric repeat, the majority of telomeric DNA is duplicated by conventional DNA replication. A fundamental step in eukaryotic DNA replication involves chromatin binding of the origin recognition complex (ORC). In human cells, telomeric repeat binding factor 2 (TRF2) is thought to play a role in the recruitment of ORC onto telomeres. To better understand the mechanism of TRF2-mediated ORC recruitment, we utilized a lacO-LacI protein tethering system in U2OS cells and found that ectopically targeted TRF2, but not TRF1, can recruit ORC onto the lacO array. We further found that the TRF homology (TRFH) dimerization domain of TRF2, but not its mutant defective in dimerization, is sufficient for ORC and minichromosome maintenance (MCM) recruitment. Mutations impairing the dimerization also compromised ORC recruitment by full-length TRF2. Similar results were obtained using immunoprecipitation and GST pull-down assays. Together, these results suggest that dimerized TRF2 recruits ORC and stimulates pre-replication complex (pre-RC) formation at telomeres through the TRFH domain.

SLX4-XPF mediates DNA damage responses to replication stress induced by DNA-protein interactions.

The DNA damage response (DDR) has a critical role in the maintenance of genomic integrity during chromosome replication. However, responses to replication stress evoked by tight DNA-protein complexes have not been fully elucidated. Here, we used bacterial LacI protein binding to lacO arrays to make site-specific replication fork barriers on the human chromosome. These barriers induced the accumulation of single-stranded DNA (ssDNA) and various DDR proteins at the lacO site. SLX4-XPF functioned as an upstream factor for the accumulation of DDR proteins, and consequently, ATR and FANCD2 were interdependently recruited. Moreover, LacI binding in S phase caused underreplication and abnormal mitotic segregation of the lacO arrays. Finally, we show that the SLX4-ATR axis represses the anaphase abnormality induced by LacI binding. Our results outline a long-term process by which human cells manage nucleoprotein obstacles ahead of the replication fork to prevent chromosomal instability.

A Phase I Study of the Anti-CC Chemokine Receptor 4 Antibody, Mogamulizumab, in Combination with Nivolumab in Patients with Advanced or Metastatic Solid Tumors.

PURPOSE: Regulatory T cells (Tregs) expressing CC chemokine receptor 4 (CCR4) can suppress antitumor immune responses and are associated with poor prognoses in several cancers. We assessed the safety and efficacy of combined mogamulizumab (anti-CCR4 antibody) and nivolumab [anti-programmed death-1 (PD-1) antibody] in immunotherapy-naïve patients with advanced/metastatic solid tumors. PATIENTS AND METHODS: This study (NCT02476123) comprised dose-escalation (3+3 design) and expansion parts. Patients received nivolumab (3.0 mg/kg) every 2 weeks, with mogamulizumab (0.3 or 1.0 mg/kg in dose escalation, 1.0 mg/kg in expansion) once weekly for 4 weeks, then every 2 weeks, until progression or unacceptable toxicity. Primary objective was safety; secondary objectives were antitumor effects, pharmacokinetics, and immunogenicity. Exploratory biomarker analyses were conducted. RESULTS: Ninety-six patients were enrolled (July 2015-November 2016): six patients in the dose-escalation part and 90 in the expansion part. No dose-limiting toxicities were observed in the dose-escalation part. Grade 3/4 treatment-related adverse events (TRAEs) occurred in 29% of patients in the expansion part (no grade 5 TRAEs). The most frequent TRAEs were rash (39%), rash maculopapular (20%), diarrhea (13%), stomatitis (12%), and pruritus (11%). There were four (27%) confirmed tumor responses among 15 patients with hepatocellular carcinoma, and one confirmed and two unconfirmed responses among 15 patients with pancreatic adenocarcinoma. During treatment, populations of effector Tregs (CD4+CD45RA-FoxP3high) decreased and CD8+ T cells in tumor-infiltrating lymphocytes increased. CONCLUSIONS: Combining an anti-PD-1 antibody, nivolumab, with a Treg-depleting anti-CCR4 antibody, mogamulizumab, provides an acceptable safety profile, antitumor activity, and a potentially effective option in cancer immunotherapy.