Current prognostic factors of advanced gastric cancer patients treated with chemotherapy: real world data from a Japanese 12 institutions.

BACKGROUND: Understanding the prognostic factors of advanced gastric cancer before starting chemotherapy is important to determine personalized treatment strategies. However, the details of chemotherapy and the prognosis of advanced gastric cancer patients have changed with the time and environment. The aim of this study was to understand the current reality of chemotherapy and to estimate the prognostic factors of advanced gastric cancer patients before starting chemotherapy at multiple centers. This includes specialized cancer hospitals and community hospitals, with the latest data under the Japanese insurance system. METHODS: We evaluated the clinical parameters and treatment details of 1025 patients who received systemic chemotherapy for unresectable advanced gastric cancer from 2012 to 2018 at 12 institutions in Japan. Prognostic factors were analyzed using the Cox proportional hazards regression model. RESULTS: As of April 2021, 953 (93%) patients had died, while 72 (7%) patients survived. The median overall survival and progression-free survival of first-line chemotherapy was 11.8 months (95% confidence interval, 10.8-12.3 months) and 6.3 months (95% confidence interval, 5.9-6.9 months), respectively. Multivariate analysis revealed eight prognostic factors: age < 40 years, performance status ≥2, no gastrectomy, diffuse histological type, albumin <3.6, alkaline phosphatase ≥300, creatinine ≥1.0 and neutrophil-to-lymphocyte ratio > 3.0. Patients using trastuzumab showed better survival than patients without (16.1 months vs. 11.1 months; P = 0.0005). CONCLUSIONS: We identified eight prognostic factors for patients with advanced gastric cancer undergoing Japanese standard chemotherapy. Our results will help clinicians develop treatment strategies for every patient.

Linked Color Imaging (LCI) Emphasizes the Color Changes in the Gastric Mucosa After Helicobacter pylori Eradication.

BACKGROUND: Diffuse redness is a characteristic endoscopic finding that indicates current infection of Helicobacter pylori, which is reduced after successful eradication. Linked color imaging (LCI) has been reported to improve the visibility of diffuse redness compared to white light imaging (WLI); however, quantitative evaluation has not been reported. AIMS: This study aimed to objectively evaluate the color change of the gastric mucosa after H. pylori eradication. METHODS: Images of the greater curvature of the antrum and corpus were captured, and the sites were biopsied during esophagogastroduodenoscopy (EGD) before and 1 year after eradication. The region of interest (ROI) was set around the biopsied area on the images. The color difference (ΔE) before and after eradication was calculated using the CIE L*a*b* color space. The association between the histological evaluation and the color value of the corresponding ROI was determined. RESULTS: At the antrum, there was no significant color change with either mode. At the corpus, the a* value, which reflected redness, decreased significantly after eradication with both modes (WLI: 41.2 to 36.0, LCI: 37.5 to 25.5); the b* value, reflecting yellowish, decreased with WLI, but increased significantly with LCI (WLI: 44.6 to 41.6, LCI: 23.9 to 29.2). The ΔE was significantly larger with LCI than with WLI (16.5 vs. 8.6). The a* values at the corpus were generally associated with histological neutrophil infiltration. CONCLUSIONS: Quantitative evaluation revealed that LCI emphasizes the change in color of the gastric mucosa due to the reduction in diffuse redness.

Prognosis after curative resection for stage IA gastric cancer in elderly patients: endoscopic submucosal dissection versus surgery.

PURPOSE: To establish whether gastrectomy for early gastric cancer (EGC) in elderly patients is related to poor survival. METHODS: The subjects of this retrospective study were patients aged ≥ 75 years with primary stage IA EGC, who underwent curative resection with endoscopic submucosal dissection (ESD) or surgery. RESULTS: We analyzed data on 365 patients who underwent ESD and 170 patients who underwent surgery. Overall survival (OS) was not significantly different for the ESD group vs. the surgery group (5-year cumulative rates, 81.5% vs. 79.7%; log-rank test, P = 0.506). Multivariate analysis revealed that treatments; namely, ESD or surgery, were not associated with OS (hazard ratio 1.09, 95% confidence interval 0.77-1.51). Similar results were observed even in the subgroups with worse conditions, such as age > 80 years, Eastern Cooperative Oncology Group performance status 2-3, Charlson comorbidity index ≥ 2, and prognostic nutritional index ≤ 46.7. Using propensity score matching, we selected 88 pairs of patients who underwent ESD or surgery with baseline characteristics matched and found that OS was not different between the two groups (log-rank test, P = 0.829). CONCLUSION: OS was comparable for elderly patients who underwent ESD and those who underwent surgery for EGC. Surgical invasiveness did not worsen the prognosis, even for elderly patients.

Tolerability and efficacy of the concentration of iodine solution during esophageal chromoendoscopy: a double-blind randomized controlled trial.

BACKGROUND AND AIMS: Esophageal chromoendoscopy with iodine solution is an important diagnostic method for the detection of superficial esophageal cancer. However, the concentration of iodine solution has differed among reports. This study aimed to evaluate patient discomfort with different iodine concentrations. METHODS: We performed a prospective, double-blind, randomized study. We prospectively enrolled and analyzed 77 patients who were at high risk for esophageal carcinoma and scheduled to undergo EGD from March 2018 to January 2019. All patients were divided into 2 groups before the procedure to compare pain measurements: a 1% iodine solution group (group A) and a 2% iodine solution group (group B). The primary endpoint of this study was the difference in pain measurement between 1% and 2% iodine solution chromoendoscopy. Secondary endpoints were safety, detection yield, and color evaluation based on both the endoscopist's survey and color values, as determined using the Commission Internationale de l'Eclairage (CIELAB, Vienna, Austria) color evaluation system, in the iodine-faded and iodine-stained area of each group. RESULTS: Heartburn and retrosternal pain in group A were significantly lower than those in group B (P = .02). Eleven patients reported heartburn and retrosternal pain (group A, 2; group B, 9). Four patients reported pain above the sternal angle and 7 below the sternal angle. There was no significant difference between the 2 groups with regard to detection yield, color evaluation by the endoscopist's assessment, or color values. No patients had any adverse events, and all safely completed this study. CONCLUSIONS: The 2% iodine solution resulted in significantly greater pain than the 1% iodine solution, and the color of the stained esophageal images of each group was the same from this study. Therefore, the 1% iodine solution is recommended for esophageal chromoendoscopy. (Clinical trial registration number: UMIN 000029796.).

Evaluation of the Usefulness and Convenience of the Kyoto Classification of Gastritis in the Endoscopic Diagnosis of the Helicobacter pylori Infection Status.

BACKGROUND/AIMS: The Kyoto Classification of Gastritis was published in 2014. Although this classification is now widely used in Japan, its usefulness and convenience have not been sufficiently evaluated. This study aimed to evaluate the usefulness and convenience of this classification in the endoscopic diagnosis of Helicobacter pylori infection. METHODS: We made a test for the endoscopic diagnosis of H. pylori infection comprising 30 cases who had representative endoscopic features of non-, active, or inactive gastritis. Thirty-eight participants took the test before and after a brief mini-lecture on the Kyoto Classification of Gastritis. Eighteen participants took the test again 3 months later. We investigated the accuracy before, just after, and 3 months after the mini-lecture. RESULTS: The accuracy of endoscopists after the lecture was significantly improved in comparison to before the lecture (77.6 vs. 83.3%). Medical students also showed significantly improved accuracy after the lecture (56.7 vs. 71.7%). Among endoscopists, this improvement was maintained after 3 months. Before the lecture, the accuracy of diagnosing non-gastritis was 90.3%; it tended to be further improved 3 months later (96.5%). A >10% point increase was observed in diagnosing active (72.7-83.3%) and inactive gastritis (73.2-84.3%) at 3 months after the lecture in comparison to before the lecture. CONCLUSION: A brief mini-lecture on the Kyoto Classification of Gastritis improved the accuracy in the endoscopic diagnosis of gastritis, indicating that understanding this classification is useful for the prompt diagnosis of H. pylori infection during esophagogastroduodenoscopy.

Blue laser imaging and linked color imaging improve the color difference value and visibility of colorectal polyps in underwater conditions.

BACKGROUND AND AIM: Underwater endoscopic mucosal resection (UEMR) has become widespread for treating colorectal polyps. However, which observational mode is best suited for determining polyp margins underwater remains unclear. To determine the best mode, we analyzed three imaging modes: white light imaging (WLI), blue laser imaging (BLI) and linked color imaging (LCI). METHODS: Images of consecutive colorectal polyps previously examined by these three modes before UEMR were analyzed according to the degree of underwater turbidity (transparent or cloudy). Color differences between the polyps and their surroundings were calculated using the Commission Internationale d'Eclairage Lab color space in which 3-D color parameters were expressed. Eight evaluators, who were blinded to the histology, scored the visibility from one (undetectable) to four (easily detectable) in both underwater conditions. The color differences and visibility scores were compared. RESULTS: Seventy-three polyps were evaluated. Sixty-one polyps (44 adenomatous, 17 serrated) were observed under transparent conditions, and 12 polyps (seven adenomatous, five serrated) were observed under cloudy conditions. Under transparent conditions, color differences for the BLI (8.5) and LCI (7.9) were significantly higher than that of WLI (5.7; P < 0.001). Visibility scores for BLI (3.6) and LCI (3.4) were also higher than that of WLI (3.1; P < 0.0001). Under cloudy conditions, visibility scores for LCI (2.9) and WLI (2.7) were significantly higher than that of BLI (2.2; P < 0.0001 and P = 0.04, respectively). CONCLUSIONS: BLI and LCI were better observational modes in transparent water; however, BLI was unsuitable for cloudy conditions.

Postoperative bleeding risk after gastric endoscopic submucosal dissection during antithrombotic drug therapy.

BACKGROUND AND AIM: The safety of gastric endoscopic submucosal dissection (ESD) in the antithrombotic drug users remains controversial. METHODS: Patients who underwent gastric ESD at Okayama University Hospital between March 2006 and February 2016 were enrolled. This study investigated the risk of post-ESD bleeding according to the management of the antithrombotic drugs. RESULTS: One thousand twenty lesions (872 patients) were enrolled. In a multivariate analysis, heparin replacement (odds ratio [OR] 5.0, 95% confidence interval [CI] 1.8-14), multiple antithrombotic drug use (OR 2.9, 95% CI 1.1-6.9), a resected specimen of ≥ 33 mm in diameter (OR 2.7, 95% CI 1.5-5.4), Helicobacter pylori negativity (OR 2.2, 95% CI 1.3-3.7), and tumors located in the lower third of the stomach (OR 1.7, 95% CI 1.0-2.9) were significant risk factors for post-ESD bleeding, while the continuation of aspirin or cilostazol was not (OR 2.6, 95% CI 0.72-7.8). The bleeding rate of the continuation group was comparable with that of the all cessation group among single antithrombotic drug users (4.5% vs 4.4%, P = 1.0); however, the rate of the continuation group was significantly higher than that of the all cessation group among multiple antithrombotic drug users (67% vs 15%, P = 0.020). CONCLUSIONS: The risk of post-ESD bleeding differed according to the management of the antithrombotic drugs. The gastric ESD under the cessation or continuation of aspirin or cilostazol monotherapy was acceptable. However, multiple antithrombotic drug use or heparin replacement was associated with a higher risk of post-ESD bleeding.

[Rupture of small intestinal varices diagnosed by CTAP and gastrointestinal bleeding scintigraphy and treated by percutaneous phlebosclerozation angioembolization].

A 55-year-old man was admitted to our hospital because of massive gastrointestinal bleeding. He had a history of type B liver cirrhosis, multiple abdominal surgeries, and endoscopic treatment of esophageal varices. Colonoscopy was performed, but the source of bleeding could not be identified. Computed tomography during arterial portography (CTAP) demonstrated small intestinal varices and collateral veins from the superior mesenteric vein to the epigastric vein. We performed phlebosclerozation by directly puncturing the epigastric vein under the skin. Remission of bleeding was then attained. No recurrence of gastrointestinal hemorrhage has occurred after the phlebosclerozation. We believe that CTAP is useful when diagnosing small intestinal varices and that percutaneous phlebosclerozation should be considered as a treatment option for small intestinal varices.

Endoscopic and Histological Gastritis in University Students with Helicobacter pylori Infection.

Objective Although the characteristics of Helicobacter pylori infection have been extensively reported, there is a lack of consensus regarding its characteristics in young adults. The present study examined the endoscopic and histological characteristics of young adults who underwent eradication therapy for H. pylori infection. Methods We examined the H. pylori infection status of first-year students at Okayama University School of Medicine and Dentistry between 2014 and 2020. A total of 152 (6.8%) students who were positive for H. pylori antibody or pepsinogen tests were enrolled in the study. Among them, 107 students underwent endoscopy, and their biopsy samples were investigated. Seventy-five students were diagnosed with H. pylori infections. Results Of 75 H. pylori-positive patients, 57 (76.0%) had endoscopic atrophic gastritis, and 42 (56.0%) had histological atrophy. A few patients had severe atrophic gastritis. All 65 patients who underwent an eradication assessment were successfully treated. After successful eradication, 26 patients underwent endoscopic follow-up. The mean follow-up period was 32.9 months. A histological evaluation revealed that gastric antrum atrophy had subsided in 11 of 14 patients, and atrophy in the lesser curvature of the gastric body had subsided in 7 of 8 patients. Conclusion More than half of young adults with H. pylori infection had atrophic gastritis. We found mild atrophy in young adults, which subsided shortly after eradication treatment. This study provides a foundation for future studies to evaluate the validity of eradication therapy in preventing gastric cancer in patients.

Degree of pharyngeal deformation caused by pharyngeal endoscopic submucosal dissection is associated with the incidence of aspiration pneumonia.

Background and study aims Endoscopic submucosal dissection (ESD) is one of the most minimally invasive treatments for superficial squamous cell cancer of the pharynx. However, aspiration pneumonia (AsP) associated with postoperative deformity of the pharynx may occur. The purpose of this study was to investigate the frequency of AsP and the degree of pharyngeal deformity after pharyngeal ESD. Patients and methods This was a retrospective observational study of patients who underwent pharyngeal ESD at Okayama University Hospital between 2006 and 2017. The degree of pharyngeal deformation was assessed using the pharyngeal deformation grade (PDG). The primary endpoint was the frequency of AsP as a long-term adverse event. Results Among the 52 patients enrolled, nine developed aspiration pneumonia, with a 3-year cumulative incidence of 9.0 % (95 % confidence interval [CI], 3.3 %-22.0 %). There were 16, 18, 16, and two patients that had PDG 0, 1, 2, and 3, respectively. Patients with a history of radiotherapy, as a treatment of head and neck cancer (44.4 % vs. 11.6 %; P  = 0.02) and the high PDG group (PDG 2 and 3) (77.8 % vs. 25.6 %; P  = 0.005) had a significantly higher incidence of AsP. The 3-year cumulative incidence rate of AsP after ESD in the high PDG group was significantly higher than that in the low PDG group (PDG 0 and 1) (23.9 % [95 %CI, 9.2.-49.5%] vs. 0 %; P  = 0.03). Conclusions The incidence of aspiration pneumonia in the long-term course after pharyngeal ESD was revealed. The incidence of aspiration pneumonia may be associated with pharyngeal deformity, but further studies are needed.

Risk Factors for Gastric Cancer after the Eradication of Helicobacter pylori Evaluated Based on the Background Gastric Mucosa: A Propensity Score-matched Case-control Study.

Objective The eradication of Helicobacter pylori (H. pylori) reduces the risk for gastric cancer (GC) development, but it cannot prevent GC completely. We investigated the risk factors of early GC development after the eradication of H. pylori, based on the histological characteristics of gastric mucosa. Methods Sixty-one patients who underwent endoscopic submucosal dissection for early GC after successful H. pylori eradication (Group A) and 122 patients without developing a gastric neoplasm over 3 years after successful H. pylori eradication (Group B) were analyzed. We compared the histological findings of the patients enrolled in Group A and Group B before and after the propensity score-matching. Results Comparing the characteristics of two the groups, Group A consisted predominantly of males, had significantly more elderly patients, and the years after successful eradication tended to be longer. We performed score matching for these three factors to reduce the influence of any confounding factors. After matching, the scores of inflammation for Group A (n=54) was significantly higher than those of Group B (n=54) at the greater curvature of the antrum, the lesser curvature of the corpus, and the greater curvature of the corpus. According to a multivariate analysis, inflammation of the greater curvature of the antrum and lesser curvature of the corpus were found to be independent risk factors. The risk ratio and 95% CI were 5.92 (2.11-16.6) (p<0.01), and 3.56 (1.05-13.2) (p=0.04), respectively. Conclusion A continuous high level of inflammation of the background gastric mucosa may be a risk factor for gastric cancer onset after H. pylori eradication.

Association Between Immune-Related Adverse Events and the Prognosis of Patients with Advanced Gastric Cancer Treated with Nivolumab.

BACKGROUND: Little is known about the association between immune-related adverse events (irAEs) and the efficacy and survival outcomes of nivolumab in patients with advanced gastric cancer (AGC). OBJECTIVE: The present study examined the association between irAEs and the prognosis of patients with AGC treated with nivolumab. PATIENTS AND METHODS: From July 2017 to November 2020, patients who had been diagnosed with advanced unresected gastric cancer and treated with nivolumab at our institution were included in this analysis. We compared the clinical and survival outcomes between the irAE and non-irAE groups. We also evaluated the factors associated with better survival in patients treated with nivolumab. RESULTS: A total of 52 patients were included in the present study, and irAEs were observed in 13 (25%). Among the patients with measurable lesions (n = 29), the disease control rates were significantly higher in the irAE group than in the non-irAE group (88 vs. 24%; P = 0.0033). At the 8- and 12-week landmark analyses, the median overall survival (OS) in the irAE group was significantly longer than that in the non-irAE group, whereas the median progression-free survival was comparable between the groups. A multivariate analysis by Cox proportional hazard regression at the 8-week landmark revealed that the development of irAEs (hazard ratio 0.18; 95% confidence interval 0.0099-0.86) alone was positively associated with a longer OS. CONCLUSIONS: The development of irAEs might be associated with survival outcomes with nivolumab treatment in patients with AGC.

Four Cases of Desquamative Esophagitis Occurring after Hematopoietic Stem Cell Transplantation.

We herein report four patients with desquamative esophagitis that developed one to nine days after peripheral blood stem cell transplantation (PBSCT). Three patients underwent allogeneic PBSCT for leukemia, and the other underwent autologous PBSCT for pineoblastoma. Esophagogastroduodenoscopy revealed mucosal sloughing and fresh blood in the esophagus. Fasting and intravenous proton pump inhibitor therapy in addition to blood transfusion improved the esophageal lesions within five to seven days in three patients. These cases indicate that desquamative esophagitis can occur in patients who receive hematopoietic stem cell transplantation. Although blood transfusions may be required, it can be resolved within seven days.

Association of host immunity with Helicobacter pylori infection in recurrent gastric cancer.

BACKGROUND: Helicobacter pylori infection is associated with the incidence of gastric cancer. Endoscopic resection has been developed as a proper technique to treat early stage of gastric cancer. However, some patients develop recurrent gastric cancer within 5 years after endoscopic treatment. The aim of the present study is to explore a biomarker for detecting people who has high risk of gastric cancer recurrence. METHODS: We analyzed the Interleukin-10 (IL-10) single nucleotide polymorphism (SNP) and IgG subclass responses to the bacteria in patients with early gastric cancer and recurrent gastric cancer. RESULTS: Patients with hetero-type in the 1082 SNP and CC genotype in the 592 SNP were at high risk of recurrence of gastric cancer. In patients with genotype carrying high risk of recurrence, IgG1 level tended to be higher than that in patients with other genotypes. CONCLUSIONS: Dominance of T helper 2 (Th2) immunity controlled by IL-10 cytokine may be associated with H. pylori-associated gastric cancer recurrence.

Increase in antibiotic resistant Helicobacter pylori in a University Hospital in Japan.

BACKGROUND: Eradication effectively prevents Helicobacter pylori-associated diseases; however, H. pylori antibiotic resistance has increased throughout Japan and worldwide. This study aimed to assess rates of resistance to antibiotics; amoxicillin, clarithromycin and metronidazole in a University Hospital in Japan. MATERIALS AND METHODS: H. pylori (208 strains) were isolated from patients at the Okayama University Hospital in Japan. The minimum inhibitory concentrations (MIC) were determined using the mean values of the E-test to determine the antimicrobial susceptibilities of the strains. Sequencing and gene analysis were performed to analyze resistance genes to clarithromycin and amoxicillin. RESULTS: Rates of amoxicillin, clarithromycin, and metronidazole resistance were 13%, 48%, and 49%, respectively. Genetic analysis indicated that the A2143G point mutation in 23S rDNA is closely associated with the MIC of clarithromycin. The MIC in amoxicillin-resistant strains increased with an increase in the number of PBP1A amino acids mutations. CONCLUSION: Genetic analysis for resistant strains is not clinically effective in cases of amoxicillin resistance. Numerous bacteria with already high antibiotic resistance rates have been isolated in large hospitals such as a University Hospital. For effective eradication therapy, MIC measurement should be considered via several methods.

Clinical outcome of patients with obscure gastrointestinal bleeding during antithrombotic drug therapy.

BACKGROUND: The clinical outcome of patients with obscure gastrointestinal bleeding (OGIB) during antithrombotic drug therapy has not been fully investigated. METHODS: Patients who underwent video capsule endoscopy (VCE) for the investigation of OGIB at Okayama University Hospital from January 2009 to March 2016 were enrolled. We evaluated the VCE findings, the patterns of OGIB, and the rate of rebleeding within 1 year in antithrombotic drug users and antithrombotic drug nonusers. RESULTS: A total of 181 patients were enrolled. Among the antithrombotic drug users, the rate of VCE positivity in the patients with overt OGIB was significantly higher in comparison with patients with occult OGIB (45% versus 16%, p = 0.014), whereas there was no significant difference among the antithrombotic drug nonusers (27% versus 26%, p = 1.0). Among the antithrombotic drug users, the rate of rebleeding among the VCE-positive patients was significantly higher in comparison with the VCE-negative patients (50% versus 5.9%, p = 0.011). Moreover, among antithrombotic drug users who did not receive therapeutic intervention, the rate of rebleeding among the VCE-positive patients was significantly higher in comparison with the VCE-negative patients (75% versus 6.3%, p = 0.001). However, among the antithrombotic drug nonusers who did not receive therapeutic intervention, the rebleeding rate of the VCE-positive patients was not significantly different from that of the VCE-negative patients (20% versus 9.4%, p = 0.43). CONCLUSION: Therapeutic intervention should be considered for patients with overt OGIB who are VCE positive and who use antithrombotic drugs due to the high risk of rebleeding.

Linked color imaging (LCI), a novel image-enhanced endoscopy technology, emphasizes the color of early gastric cancer.

BACKGROUND AND STUDY AIMS: Linked color imaging (LCI) and blue laser imaging (BLI) are novel image-enhanced endoscopy technologies with strong, unique color enhancement. We investigated the efficacy of LCI and BLI-bright compared to conventional white light imaging (WLI) by measuring the color difference between early gastric cancer lesions and the surrounding mucosa. PATIENTS AND METHODS: Images of early gastric cancer scheduled for endoscopic submucosal dissection were captured by LCI, BLI-bright, and WLI under the same conditions. Color values of the lesion and surrounding mucosa were defined as the average of the color value in each region of interest. Color differences between the lesion and surrounding mucosa (ΔE) were examined in each mode. The color value was assessed using the CIE L*a*b* color space (CIE: Commission Internationale d'Eclairage). RESULTS: We collected images of 43 lesions from 42 patients. Average ΔE values with LCI, BLI-bright, and WLI were 11.02, 5.04, and 5.99, respectively. The ΔE was significantly higher with LCI than with WLI ( P  < 0.001). Limited to cases of small ΔE with WLI, the ΔE was approximately 3 times higher with LCI than with WLI (7.18 vs. 2.25). The ΔE with LCI was larger when the surrounding mucosa had severe intestinal metaplasia ( P  = 0.04). The average color value of a lesion and the surrounding mucosa differed. This value did not have a sufficient cut-off point between the lesion and surrounding mucosa to distinguish them, even with LCI. CONCLUSION: LCI had a larger ΔE than WLI. It may allow easy recognition and early detection of gastric cancer, even for inexperienced endoscopists.

Early-onset cognitive deficits and axonal transport dysfunction in P301S mutant tau transgenic mice.

Alzheimer's disease (AD) and frontotemporal lobar degeneration (FTLD) are neurodegenerative "tauopathies" characterized by hyperphosphorylated tau accumulation and neurofibrillary tangles. The P301S mutation of tau, a causal mutation of a familial type of FTLD, is believed to be involved in neurodegenerative progression. We developed a transgenic mouse, named TPR50, harboring human P301S tau. Tau phosphorylation in the hippocampus of TPR50 mice increased with age, particularly at S202/T205. Insolubilization and intracellular accumulation of tau were detected in the hippocampus by 9 months of age. Expression of calbindin was significantly reduced in 6- and 9-month-old TPR50 mice but not in 3-month-old mice. TPR50 mice demonstrated cognitive dysfunction at 5 months. At this age or earlier, although no intracellular tau accumulation was observed in the hippocampus, abnormally increased microtubule (MT)-related proteins and MT hyperdynamics in the hippocampus, and impaired axonal transport in the septo-hippocampal pathway were already observed. Therefore, cognitive dysfunction in TPR50 mice may result from early MT dysfunction and impaired axonal transport rather than accumulation of insoluble tau and neurodegeneration. TPR50 mice are a valuable new model to study progression of tauopathies at both the behavioral and neurocellular levels and may also prove useful for testing new therapies for neurodegenerative diseases.