The G9a histone methyltransferase represses osteoclastogenesis and bone resorption by regulating NFATc1 function.

Epigenetic modifications affect cell differentiation via transcriptional regulation. G9a/EHMT2 is an important epigenetic modifier that catalyzes the methylation of histone 3 lysine 9 (H3K9) and interacts with various nuclear proteins. In this study, we investigated the role of G9a in osteoclast differentiation. When we deleted G9a by infection of Cre-expressing adenovirus into bone marrow macrophages (BMMs) from G9afl/fl (Ehmt2fl/fl) and induced osteoclastic differentiation by the addition of macrophage colony-stimulating factor (M-CSF) and receptor activator of NF-κB ligand (RANKL), the number of TRAP-positive multinucleated osteoclasts significantly increased compared with control. Furthermore, the mRNA expression of osteoclast markers, TRAP, and cathepsin K, and to a lesser extent, NFATc1, a critical transcription factor, increased in G9a KO cells. Infection of wild-type (WT) G9a-expressing adenovirus in G9a KO cells restored the number of TRAP-positive multinucleated cells. In G9a KO cells, increased nuclear accumulation of NFATc1 protein and decreased H3K9me2 accumulation were observed. Furthermore, ChIP experiments revealed that NFATc1 binding to its target, Ctsk promoter, was enhanced by G9a deletion. For in vivo experiments, we created G9a conditional knock-out (cKO) mice by crossing G9afl/fl mice with Rank Cre/+ (Tnfrsf11aCre/+) mice, in which G9a is deleted in osteoclast lineage cells. The trabecular bone volume was significantly reduced in female G9a cKO mice. The serum concentration of the C-terminal telopeptide of type I collagen (CTX), a bone-resorbing indicator, was higher in G9a cKO mice. In addition, osteoclasts differentiated from G9a cKO BMMs exhibited greater bone-resorbing activity. Our findings suggest that G9a plays a repressive role in osteoclastogenesis by modulating NFATc1 function.

Lung squamous cell carcinoma responding to nivolumab retreatment six years after initial treatment: A case report.

A 61-year-old man presented to our hospital with a chief complaint of chronic cough. He was diagnosed with lung squamous cell carcinoma at clinical stage cT2aN3M1a. He received chemotherapy up to the fourth line, but both the primary tumor and lymph node metastases increased in size. Nivolumab, administered as the fifth line, resulted in a complete response (CR) that continued for 2 years and 8 months. Treatment was stopped due to the appearance of common terminology criteria for adverse events grade 1 pneumonitis. He was followed up without treatment for 3 years and 8 months, but a left supraclavicular fossa lymph node metastasis appeared. Retreatment with nivolumab was initiated, and the patient achieved CR again. One year and 6 months after retreatment, CR was maintained with nivolumab. This case represents a rare instance in which nivolumab yielded a significant response after a prolonged immune checkpoint inhibitor (ICI)-free interval. Our experience has shown that the long-term response to ICIs may deteriorate in the future. Therefore, retreatment with ICIs may be effective when the initial therapy is successful.

Multicenter Pharmacokinetic and Pharmacodynamic Study of Pembrolizumab for Non-small-Cell Lung Cancer in Patients Aged 75 Years and Older.

Pembrolizumab is a major treatment for recurrent or advanced non-small-cell lung cancer (NSCLC). However, data on its use and pharmacokinetics (PK) in older patients are limited. This open-label, multicenter, observational study evaluated real-world data on the safety, efficacy, and PK of pembrolizumab in older patients with NSCLC. In 99 patients aged ≥75 years, PK was determined by liquid chromatography-mass spectrometry on pretreatment samples. Performance status (PS), geriatric assessment (GA), overall response rate (ORR), progression-free survival (PFS), and overall survival (OS) were evaluated. The median age was 78 (75-87) years. PS was 2-3 in 14 patients. The median ORR, PFS, and OS were 47.5%, 8.0, and 20.5 months, respectively. Although PK and ORR were not significantly associated, patients with the lowest Cycle 1-trough quartile (Q1) experienced poorer PFS (Q1 vs. Q2-4; 3.4 vs. 11.8 months, P = 0.006) and OS (Q1 vs. Q2-4; 9.9 vs. 21.7 months, P = 0.005) than in other quartiles overall, and even in the PD-L1 ≥50% subset (PFS, Q1 vs. Q2-4; 4.1 vs. 14.7 months, P = 0.005; OS, Q1 vs. Q2-4; 9.4 vs. 22.1 months, P = 0.010). The Q1 subgroup was characterized by poor PS and lower albumin, and more frequent "weight loss ≥ 10%" on the GA. Pembrolizumab therapy had similar PK and efficaciousness in older as well as younger patients. In patients with PS ≥2, low albumin, and vulnerable GA, early increases in PK levels are less likely, potentially diminishing efficacy even when PD-L1 ≥50%.

Real-World Data on Subsequent Therapy for First-Line Osimertinib-Induced Pneumonitis: Safety of EGFR-TKI Rechallenge (Osi-risk Study TORG-TG2101).

BACKGROUND: Although osimertinib is a promising therapeutic agent for advanced epidermal growth factor receptor (EGFR) mutation-positive lung cancer, the incidence of pneumonitis is particularly high among Japanese patients receiving the drug. Furthermore, the safety and efficacy of subsequent anticancer treatments, including EGFR-tyrosine kinase inhibitor (TKI) rechallenge, which are to be administered after pneumonitis recovery, remain unclear. OBJECTIVE: This study investigated the safety of EGFR-TKI rechallenge in patients who experienced first-line osimertinib-induced pneumonitis, with a primary focus on recurrent pneumonitis. PATIENTS AND METHODS: We retrospectively reviewed the data of patients with EGFR mutation-positive lung cancer who developed initial pneumonitis following first-line osimertinib treatment across 34 institutions in Japan between August 2018 and September 2020. RESULTS: Among the 124 patients included, 68 (54.8%) patients underwent EGFR-TKI rechallenge. The recurrence rate of pneumonitis following EGFR-TKI rechallenge was 27% (95% confidence interval [CI] 17-39) at 12 months. The cumulative incidence of recurrent pneumonitis was significantly higher in the osimertinib group than in the first- and second-generation EGFR-TKI (conventional EGFR-TKI) groups (hazard ratio [HR] 3.1; 95% CI 1.3-7.5; p = 0.013). Multivariate analysis revealed a significant association between EGFR-TKI type (osimertinib or conventional EGFR-TKI) and pneumonitis recurrence, regardless of severity or status of initial pneumonitis (HR 3.29; 95% CI 1.12-9.68; p = 0.03). CONCLUSIONS: Osimertinib rechallenge after initial pneumonitis was associated with significantly higher recurrence rates than conventional EGFR-TKI rechallenge.

Primary lung cancer with pulmonary alveolar proteinosis treated with immune checkpoint inhibitor: A case report.

Primary lung cancer with pulmonary alveolar proteinosis (PAP) is a rare condition. We present a case of a patient with primary lung cancer with PAP treated with an immune checkpoint inhibitor (ICI). A 62-year-old man was diagnosed with autoimmune PAP 8 years prior to current admission. Lung adenocarcinoma was found in his right lung, and platinum-based chemotherapy was administered, followed by atezolizumab. He experienced disease progression after atezolizumab treatment, whereas ICI-induced pneumonia or exacerbation of PAP did not occur. This indicates that ICI may be safely used in patients with primary lung cancer with PAP.

Epigenetic modifier G9a is involved in regulation of mouse tongue development.

OBJECTIVES: The tongue comprises multiple tissues of different embryonic origins, including pharyngeal arch, somite, and cranial neural crest (CNC). However, its developmental regulatory mechanisms, especially those involving epigenetic modifiers, remain poorly understood. This study examined the roles of the epigenetic modifier G9a in murine tongue development. METHODS: We deleted G9a using Sox 9 (SRY-related HMG-box gene 9)-Cre recombinase, which acts in tongue progenitor cells, including CNC-derived cells, to generate G9a conditional knockout (cKO) mice. Histochemical and immunohistochemical analyses were conducted on sections prepared from tongue tissues of control and cKO mice. RESULTS: Cre-dependent LacZ reporter mice, generated by crossing Rosa-LacZ mice with sox9-Cre mice, revealed Cre recombinase activity in the mucosal epithelium and tongue connective tissue of the embryonic tongue. Tongue volume was significantly reduced on embryonic day 17.5 (E17.5) and postnatal day 0 (P0) in cKO mice. Histological sections showed that the lingual mucosal epithelium was thinner in cKO mice. Reduced G9a levels were accompanied by decreased levels of a G9a substrate, dimethylated lysine 9 in histone H3, in the embryonic tongue. BrdU injection at E16.5 revealed reduced numbers of BrdU-positive cells in the mucosal epithelium and underlying connective tissue at E17.5 in cKO mice, indicating suppression of cell proliferation in both tissues. Investigation of keratin 5 and 8 protein localization showed significantly suppressed expression in the lingual mucosal epithelium in cKO mice. CONCLUSIONS: G9a is required for proper proliferation and differentiation of sox9-expressing tongue progenitor cells and is thereby involved in tongue development.

Cytokine Release Syndrome More than Two Years after Pembrolizumab Introduction.

A 71-year-old man with advanced lung adenocarcinoma was treated with carboplatin, pemetrexed, and pembrolizumab in June 2020. Pemetrexed and pembrolizumab maintenance therapy were continued until November 2022. A fever and severe fatigue occurred in December 2022; however, the cause of the infection was inconclusive based on the patient's symptoms, imaging findings, and culture tests. Although the patient was administered antibiotics, his general condition worsened. Considering the possible diagnosis of immune-related cytokine release syndrome (CRS), the patient was administered prednisolone (1 mg/kg/day) and showed improvement. In conclusion, CRS can occur even long after the initial administration of immune checkpoint inhibitor therapy.