Characteristics and clinical outcomes of patients with advanced gastric or gastroesophageal cancer treated in and out of randomized clinical trials of first-line immune checkpoint inhibitors.

BACKGROUND: Although several randomized trials (RCTs) showed survival benefits of immune checkpoint inhibitor (ICI) plus first-line chemotherapy for advanced gastric or gastroesophageal cancer (AGC), these trials could enroll patients who fulfilled the strict eligibility criteria or waited for certain screening period for central assessment of PD-L1 status. METHODS: We retrospectively compared characteristics and clinical outcomes of the patients with AGC who received first-line chemotherapy in control arm of RCTs with ICIs (control group) or clinical practice (practice group) at our institution from February 2016 to April 2019. RESULTS: The control group had a better baseline Eastern Cooperative Oncology Group performance status (PS0, 81.2% vs. 51.4%, p < 0.001) and a longer interval from first visit to first-line chemotherapy initiation (19 days vs. 9 days, p < 0.001) than the practice group. Median overall survival (OS) was 20.3 months in control group and 15.7 months in practice group, with a trend of longer OS in control group than that in practice group (hazard ratio, 0.71; p = 0.062). More patients in control group were treated with subsequent chemotherapy including ICIs. CONCLUSION: Patients with AGC in RCTs of ICIs had a better PS or a higher chance to receive subsequent chemotherapy, resulting in a better prognosis than those treated in clinical practice. This information should be considered when interpreting RCT results and applying new treatments into clinical practice.

[A Survey on the Care of Patients with Cancer during the COVID-19 Pandemic].

The COVID-19 pandemic is expected to significantly impact cancer treatment due to the shortage of medical supply, including the anxiety of patients and their families-specifically those associated with the risk of infection. We conducted a questionnaire survey using the internet service formrun between March 1 and 31, 2021. A total of 126 hospitals and 65 patients responded to the survey. Telemedicine perception differed between hospitals and patients. Hospitals found telemedicine to be useful, whereas patients did not; the main reasons for this were inadequate examinations and consultations and difficulty in communicating symptoms. Although telemedicine is regarded as one of the most effective tools during the COVID-19 pandemic, there are still issues with its widespread application. Notably, it would be essential to collaborate with local hospitals to improve cancer treatment during this pandemic.

[A Case of Fournier's Gangrene during Second-Line IRIS plus Bevacizumab Chemotherapy for Rectal and Anal Canal Cancer].

A 52-year-old man diagnosed with Stage ⅢA rectal and anal canal cancer underwent abdominal perineal resection using Miles's method. Two years later, local recurrence and lung metastases were detected using contrasted CT imaging. First-line chemotherapy of XELOX was administered for 4 months until the disease progressed and lung metastases developed. After 4 courses of second-line IRIS plus bevacizumab chemotherapy, fever and swelling of the right buttock appeared; he visited and was admitted to our hospital. A CT scan revealed a pelvic abscess which resulted in septic shock. Swelling and pain extended to the right scrotum, and acute necrotizing fasciitis was suspected, and emergency surgery was performed. An incision was made from the right buttock to the right scrotum, bloody purulent drainage with a foul odor was observed, and a diagnosis of Fournier's gangrene was made. Although typical CT findings such as emphysema due to gas-producing bacteria were not observed in this case, early diagnosis and intervention of systemic management including early surgical drainage and operation were effective. For pelvic infections occurring during bevacizumab chemotherapy, Fournier's gangrene should considered for differential diagnosis, even if CT findings are atypical.

Prospective evaluation and refinement of an S-1 dosage formula based on renal function for clinical application.

In patients with impaired renal function, S-1-related toxicities increase due to higher exposure of 5-fluorouracil (5-FU). Our previous pharmacokinetic study in 16 cancer patients with various renal functions developed an S-1 dosage formula based on individual creatinine clearance (CLcr) and body surface area (BSA). To evaluate and refine the formula, this prospective study was conducted. Thirty-three patients with various renal functions received S-1 for 4 weeks at doses determined by the nomogram derived from the previously developed formula. A series of blood samples were collected after the first dose to calculate the area under the concentration-time curve (AUC) of 5-FU. Thirty patients with BSA of 1.14-1.84 m2 and CLcr of 23.8-96.4 mL/min were assessable for pharmacokinetics. The observed daily AUC ranged from 712.6 to 2868.7 ng·h/mL, and 18 patients achieved the target AUC (1447.8 ± 545.4 ng·h/mL). Three patients experienced S-1-related grade 3 adverse events during the first course. In the population pharmacokinetic analysis from the combined data of 46 patients in this study and the previous study, sex was identified as a statistically significant covariate for 5-FU clearance. Hence, the refined formula includes sex as an additional factor: Recommended daily dose = target AUC × (14.5 + 8.23 × SEX [0 for female and 1 for male] + 0.301 × CLcr) × BSA. Revised nomograms for recommended daily doses derived from the refined formula can be used in clinical practice to achieve the target AUC ensuring efficacy and safety of S-1.

Significant Improvement After Surgery for a Symptomatic Osteoblastoma in a Patient with Camurati-Engelmann Disease: Case Report and Literature Review.

Camurati-Engelmann disease (CED) is a rare, progressive diaphyseal dysplasia characterized as diaphyseal hyperostosis and sclerosis of the long bones. Corticosteroids, bisphosphonates, and losartan have been reported to be effective systemic medications used to reduce CED symptoms. There are no reports of osteoblastoma in patients with CED, and osteoblastoma in the distal radius is rare. We present a patient diagnosed with CED, based on radiological and histological examinations, at 11 years old. At 22 years old, she experienced severe pain in her right forearm and was treated with bisphosphonate, losartan, and prednisolone; however, the pain continued. An expansive and sclerotic lesion at the distal radius was observed on radiography. A follow-up plain radiograph indicated that the lesion was growing. Fluorodeoxyglucose positron emission tomography revealed solitary, intense radiotracer uptake, and a biopsy and surgical resection were performed due to suspected malignancy. Pathologic analysis showed anastomosing bony trabeculae rimmed by osteoblasts observed in a loose fibrovascular stroma. The lesion was diagnosed as an osteoblastoma. Following bone excision and artificial bone grafting, the patient's severe pain almost completely disappeared. At final follow-up, no evidence of osteoblastoma recurrence was noted. To our knowledge, this is the first case report of osteoblastoma arising in a patient with CED. Bone excision and artificial bone grafting may be a treatment option for local symptomatic osteoblastoma in patients with CED.

Glycogen synthase kinase 3ß as a potential therapeutic target in synovial sarcoma and fibrosarcoma.

Soft tissue sarcomas (STSs) are a rare cancer type. Almost half are unresponsive to multi-pronged treatment and might therefore benefit from biologically targeted therapy. An emerging target is glycogen synthase kinase (GSK)3ß, which is implicated in various diseases including cancer. Here, we investigated the expression, activity and putative pathological role of GSK3ß in synovial sarcoma and fibrosarcoma, comprising the majority of STS that are encountered in orthopedics. Expression of the active form of GSK3ß (tyrosine 216-phosphorylated) was higher in synovial sarcoma (SYO-1, HS-SY-II, SW982) and in fibrosarcoma (HT1080) tumor cell lines than in untransformed fibroblast (NHDF) cells that are assumed to be the normal mesenchymal counterpart cells. Inhibition of GSK3ß activity by pharmacological agents (AR-A014418, SB-216763) or of its expression by RNA interference suppressed the proliferation of sarcoma cells and their invasion of collagen gel, as well as inducing their apoptosis. These effects were associated with G0/G1-phase cell cycle arrest and decreased expression of cyclin D1, cyclin-dependent kinase (CDK)4 and matrix metalloproteinase 2. Intraperitoneal injection of the GSK3ß inhibitors attenuated the growth of SYO-1 and HT1080 xenografts in athymic mice without obvious detrimental effects. It also mitigated cell proliferation and induced apoptosis in the tumors of mice. This study indicates that increased activity of GSK3ß in synovial sarcoma and fibrosarcoma sustains tumor proliferation and invasion through the cyclin D1/CDK4-mediated pathway and enhanced extracellular matrix degradation. Our results provide a biological basis for GSK3ß as a new and promising therapeutic target for these STS types.

[A Case of Recurrent Premenopausal Hormone Receptor Positive Breast Cancer with Liver, Lung and Bone Metastasis Successfully Treated with Endocrine Therapy].

Here we report a 48-year-old female with recurrent breast cancer. She had received chest muscle-conserving mastectomy and lymph node dissection at another hospital, diagnosed as pStage ⅡB, T2N1M0 premenopausal left endocrine positive/ HER2 negative breast cancer at the age of 45. Although postoperative adjuvant therapy was started with LH-RH agonist plus tamoxifen, and chest radiation, tamoxifen therapy was intolerantly discontinued due to severe adverse events of hot flash after 1 year later. Three years later, she presented with back pain and was referred to our hospital. As PET-CT revealed recurrence of multiple bone and lung metastases and solitary liver metastasis which did not seem to be life-threatening, palliative radiation therapy and endocrine therapy with leuprorelin and anastrozole(LA)were started. Eighteen months later, PET-CT showed complete disappearance of liver and lung metastases and remarkable regression of bone metastases except for the right sciatic bone. LA therapy could be maintained for a total of 30 months until metastatic recurrence on liver and bone emerged. LA endocrine therapy may be effective for patients with premenopausal hormone-positive breast cancer even if the difficult situation such as tamoxifen intolerance.

[A Case of Long-Term Survival in a Patient with Recurrence of Peritoneal Dissemination after Resection of Pancreatic Tail Cancer].

A 60-year-old man underwent distal pancreatectomy with splenectomy and combined resection partially of the stomach, jejunum, and left renal vein. We administered S-1 adjuvant chemotherapy for 1 year. After its completion, the patient showed no evidence of recurrence. However, his carbohydrate antigen(CA)19-9 level was elevated for 1 year and 8 months postoperatively. We administered gemcitabine chemotherapy. He was admitted for bowel obstruction 3 years and 10 months postoperatively. Conservative treatment with an ileus tube did not improve the bowel obstruction. Therefore, we performed the surgery. Intraoperative findings revealed peritoneal nodules invading the small intestine. We performed a small bowel bypass. Pathological examination revealed the peritoneal nodule of pancreatic cancer. Although we administered FOLFIRINOX chemotherapy postoperatively, his CA19-9 level remained elevated for 4 years and 8 months after the first surgery. Therefore, chemotherapy was changed to gemcitabine and nab-paclitaxel. Six years and 11 months after the first surgery and 5 years and 3 months after the diagnosis of peritoneal dissemination, he survives with recurrence. Herein, there were 2 contributors to long-term survival; the patient not only showed positive responses to each chemotherapy regimen but could also continue chemotherapy without developing significant adverse effects.

[A Case of Pancreatic Mucinous Cystic Carcinoma with Bilateral Lung Metastases].

A 48-year-old female visited former doctor with abdominal pain and bloating. She was suspected of having pancreatic tumor and referred to our hospital. Abdominal dynamic CT showed multilocular cystic tumor in the pancreatic tail, and chest CT showed multiple lung nodules. From these findings, the patient was diagnosed mucinous cystic carcinoma(MCC)with lung metastases. We performed distal pancreatectomy for the first and lung resection after pancreatectomy. After all, the pathological diagnosis was MCC and metastatic lung cancer from the MCC. The adjuvant chemotherapy was not performed. Eleven months after pancreatectomy and 6 months after lung resection, the patient is still alive without recurrence.

Post-progression survival following second-line chemotherapy in patients with advanced pancreatic cancer previously treated with gemcitabine: a meta-analysis.

Background Post-progression survival (PPS) could be a confounding element in interpreting data from clinical trials of second-line chemotherapy in patients with advanced pancreatic cancer (PC) previously treated with gemcitabine (GEM) because a recent meta-analysis of oxaliplatin combination therapy showed statistical heterogeneity for overall survival (OS) but not for progression-free survival (PFS). This study aimed to improve the understanding of the impact of PPS on OS in this setting. Methods Databases were searched to identify randomized controlled trials (RCTs) in the salvage setting. We evaluated relationships between OS and PFS, PPS, and other variables. Results Totally, 17 RCTs with 3253 patients were identified. Median OS was strongly and moderately associated with median PPS and PFS, respectively (r = 0.913; p < 0.001 and 0.780; p < 0.001, respectively). The proportion of patients with good performance status was significantly associated with both PPS and PFS (r = 0.574, p < 0.001 and 0.492, p < 0.001, respectively). The induction rate of subsequent chemotherapy was related to the duration of PPS and OS (r = 0.640, p < 0.001 and 0.647, p < 0.001, respectively). Median PPS and OS were significantly longer in recent trials than those in older trials (3.55 versus 2.78 months, p < 0.001 and 6.29 versus 5.02 months, p < 0.001). Conclusions Median PPS was strongly correlated with median OS. Given the recently increased opportunity for subsequent chemotherapy and supportive care, PPS may serve as an important element to clarify problems in this setting.

The usefulness of wide excision assisted by a computer navigation system and reconstruction using a frozen bone autograft for malignant acetabular bone tumors: a report of two cases.

BACKGROUND: Difficult resection of tumors from regions with complex local anatomy, such as the pelvis and sacrum, is likely to result in inadequate surgical margins (intralesional or marginal); this is because three-dimensional osteotomy is difficult particularly around the acetabulum. Additionally, removal of the joint makes reconstruction very difficult; thus, retention of good function also becomes difficult. In musculoskeletal oncology, computer navigation systems are still not widely used to prevent tumor-positive margins. We performed wide excision with guidance from a computer navigation system and reconstruction using frozen bone autografts for malignant pelvic bone tumors in two patients, and we obtained excellent functional and oncological outcomes. Here we present these patients and discuss our approach. CASE PRESENTATION: Case 1: A 12-year-old girl presented with Ewing sarcoma of the left pelvis (PI-II). We performed wide excision assisted by a computer navigation system with the osteotomy of the load surface of acetabulum and reconstruction using a frozen bone autograft. At the final follow-up, she showed excellent function and was alive without the disease. Moreover, she did not have osteoarthritis of the left hip joint. Case 2: A 71-year-old woman presented with dedifferentiated chondrosarcoma of the right pelvis (PII-III). We performed wide excision assisted by a computer navigation system with osteotomy avoiding load surface of the acetabulum and reconstruction using a frozen bone autograft; there was no tumor at the load surface. At the final follow-up, she showed good function, was alive without the disease, and did not have osteoarthritis of the left hip joint. CONCLUSIONS: Wide excision assisted by a computer navigation system and reconstruction using a frozen bone autograft are very useful for the management/treatment of extremely difficult cases such as malignant pelvic bone tumors, particularly those including the acetabulum.

Knee joint preservation surgery in osteosarcoma using tumour-bearing bone treated with liquid nitrogen.

PURPOSE: To preserve the joint structure in order to maintain good limb function in patients with osteosarcoma, we perform epiphyseal or metaphyseal osteotomy and reconstruction using frozen autografts that contain a tumour treated with liquid nitrogen. There are two methods of using liquid nitrogen-treated autografts: the free-freezing method and the pedicle-freezing method. The purpose of this study was to evaluate the results of intentional joint-preserving reconstruction using the free-freezing method and the pedicle-freezing method in patients with osteosarcoma. METHODS: Between 2006 and 2014, we performed joint-preserving surgery (12 with the free-freezing method and six with the pedicle freezing method) to treat 18 cases of osteosarcoma (12 distal femurs and six proximal tibias) in patients who had achieved a good response to neoadjuvant chemotherapy. RESULTS: Among the 18 patients (nine boys and nine girls) who had a mean age of 11.6 years, 13 remained continuously disease-free, three showed no evidence of disease, one was alive with the disease, and one died from the disease. Functional outcomes were assessed as excellent in 15 patients and poor in three, with a mean follow-up period of 46.1 months. The mean Musculoskeletal Tumour Society (MSTS) score was 90.2%. Except for one patient who underwent amputation, all patients could bend their knee through >90° flexion, and nine achieved full ROM. All but two patients could walk without aid, and 11 were able to run normally throughout the follow-up period. No intraoperative complications were observed, such as surrounding soft-tissue damage, neurovascular injury, or recurrence from frozen bone. CONCLUSIONS: Joint-preserving reconstruction using frozen autografts yielded excellent function in patients with osteosarcoma.

[Effect of tolvaptan on ascites due to malignancy].

Ascites accompanying a malignancy is often refractory to conventional treatment with saline diuretics, making it difficult to control. We administered a new diuretic, Tolvaptan, to 10 individuals with malignancy and heart failure accompanied by ascites, which was refractory to saline diuretics, and assessed its efficacy and adverse events. We observed a significant reduction in abdominal distension following 2 weeks of Tolvaptan administration. However, we also observed significant increases in serum potassium, urea nitrogen, and creatinine levels, but no serious adverse events. This suggests that Tolvaptan may also be effective as treatment for ascites.

[A case of curative resection after downsizing chemotherapy in initially unresectable locally advanced intrahepatic cholangiocarcinoma].

This case report describes an 83-year-old man with intrahepatic cholangiocarcinoma who was referred by a local hospital. Abdominal computed tomography (CT) showed a large tumor in hepatic segments 4, 5, and 8 involving the right hepatic vein and inferior vena cava, which is normally indicative of an unresectable locally advanced tumor. After systemic chemotherapy with gemcitabine and cisplatin, the observed decrease in the level of tumor marker suggested that the cancer was responding to treatment, while radiological findings showed the main tumor shrunk without the presence of distant metastases. Thus, hepatic left trisectionectomy with bile duct resection was performed after portal vein embolization. Pathological examination revealed negative margins (R0). Eighteen months after surgery, the patient is free of disease and shows no signs of recurrence. An initially unresectable, locally advanced biliary tract cancer may be down sized by chemotherapy, which makes radical resection possible, at least in a proportion of patients. This approach provides longer survival and may have a potential for disease eradication as a new multidisciplinary approach for patients with unresectable locally advanced biliary tract cancer.

Development of Au Nanoparticle Two-Dimensional Assemblies Dispersed with Au Nanoparticle-Nanostar Complexes and Surface-Enhanced Raman Scattering Activity.

We recently found that polyvinylpyrrolidone (PVP)-protected metal nanoparticles dispersed in water/butanol mixture spontaneously float to the air/water interface and form two-dimensional assemblies due to classical surface excess theory and Rayleigh-Bénard-Marangoni convection induced by butanol evaporation. In this study, we found that by leveraging this principle, a unique structure is formed where hetero gold nanospheres (AuNPs)/gold nanostars (AuNSs) complexes are dispersed within AuNP two-dimensional assemblies, obtained from a mixture of polyvinylpyrrolidone-protected AuNPs and AuNSs that interact electrostatically with the AuNPs. These structures were believed to form as a result of AuNPs/AuNSs complexes formed in the water/butanol mixture floating to the air/water interface and being incorporated into the growth of AuNP two-dimensional assemblies. These structures were obtained by optimizing the amount of mixed AuNSs, with excessive addition resulting in the formation of random three-dimensional network structures. The AuNP assemblies dispersed with AuNPs/AuNSs complexes exhibited significantly higher Raman (surface-enhanced resonance Raman scattering: SERRS) activity compared to simple AuNP assemblies, while the three-dimensional network structure did not show significant SERRS activity enhancement. These results demonstrate the excellent SERRS activity of AuNP two-dimensional assemblies dispersed with hetero AuNPs/AuNSs complexes.

Whole blood transcriptome analysis for age- and gender-specific gene expression profiling in Japanese individuals.

Whole blood transcriptome analysis is a valuable approachin medical research, primarily due to the ease of sample collection and the richness of the information obtained. Since the expression profile of individual genes in the analysis is influenced by medical traits and demographic attributes such as age and gender, there has been a growing demand for a comprehensive database for blood transcriptome analysis. Here, we performed whole blood RNA sequencing (RNA-seq) analysis on 576 participants stratified by age (20-30s and 60-70s) and gender from cohorts of the Tohoku Medical Megabank (TMM). A part of female segment included pregnant women. We did not exclude the globin gene family in our RNA-seq study, which enabled us to identify instances of hereditary persistence of fetal hemoglobin based on the HBG1 and HBG2 expression information. Comparing stratified populations allowed us to identify groups of genes associated with age-related changes and gender differences. We also found that the immune response status, particularly measured by neutrophil-to-lymphocyte ratio (NLR), strongly influences the diversity of individual gene expression profiles in whole blood transcriptome analysis. This stratification has resulted in a data set that will be highly beneficial for future whole blood transcriptome analysis in the Japanese population.

The Prognostic Nutritional Index in patients with microsatellite instability-high metastatic gastric or gastroesophageal cancers receiving immune checkpoint inhibitors.

BACKGROUND: Microsatellite instability high (MSI-H) and/or mismatch repair deficient (dMMR) status is the strongest predictive factor for immune checkpoint inhibitors (ICIs) benefit in patients with metastatic gastroesophageal cancer (mGC). Primary resistance to ICIs is a relevant issue, but prognostic and predictive factors are lacking. MATERIALS AND METHODS: In this multinational, retrospective cohort of patients with MSI-H/dMMR mGC treated with ICIs without chemotherapy we collected baseline laboratory values to establish the prognostic nutritional index (PNI). We evaluated the association between baseline PNI with the activity and efficacy of ICIs. RESULTS: At a median follow-up of 31.6 months, median progression-free survival (PFS) and 2-year PFS rate were not reached and 73.6 % in the PNI-high subgroup versus 6.3 months and 38.3 % in the PNI-low one (HR 0.32, 95 % CI: 0.16-0.61, p < .001). Median overall survival (OS) and 2-year OS rate were not reached and 81.9 % in the PNI-high subgroup versus 24.4 months and 50.5 % in the PNI-low one (HR 0.26, 95 % CI: 0.12-0.56, p < .001). In multivariable models, high PNI was associated with longer PFS and OS (HR 0.30, 95 % CI: 0.15-0.61, p <0.001 and 0.37, 95 % CI: 0.15-0.91, p = .031). CONCLUSIONS: High PNI is associated with longer PFS and OS, in patients with MSI-H mGC receiving ICIs. Patients with low baseline PNI may benefit from intensive therapeutic approaches.

Synesthesia has specific cognitive processing during Go/No-go paradigms.

Grapheme-color synesthesia is a consistent and automatic perception of non-physical color when presented with a grapheme. Many previous studies focused on the synesthetic visual system, but other cognitive functions in grapheme-color synesthetes have remained unclear. Therefore, the objective of the present study was to investigate the characteristics of cognitive processing for motor execution and inhibition during Go/No-go paradigms in grapheme-color synesthesia using event-related potentials (ERPs). Six grapheme-color synesthetes and 24 non-synesthetes performed visual, auditory, and somatosensory Go/No-go paradigms. Omission errors were higher in grapheme-color synesthetes than non-synesthetes. Group-trial interactions (i.e., synesthetes-non-synesthetes × Go-No-go) were observed for the latency of the visual N2 component and amplitude of the somatosensory N2 component. Latencies of auditory and somatosensory P3 components were shorter in grapheme-color synesthetes than non-synesthetes. These findings suggest that grapheme-color synesthetes have specific cognitive processing in motor execution and inhibition as well as synesthetic color perception. Our data advance understanding of cognitive processing in grapheme-color synesthesia.

Erythritol Can Inhibit the Expression of Senescence Molecules in Mouse Gingival Tissues and Human Gingival Fibroblasts.

Oral aging causes conditions including periodontal disease. We investigated how the sugar alcohol erythritol, which has anti-caries effects, impacts aging periodontal tissues and gingival fibroblasts in mice and humans in vivo and in vitro. Mice were classified into three groups: control groups of six-week-old (YC) and eighteen-month-old mice (AC) and a group receiving 5% w/w erythritol water for 6 months (AE). After rearing, RNA was extracted from the gingiva, and the levels of aging-related molecules were measured using PCR. Immunostaining was performed for the aging markers p21, γH2AX, and NF-κB p65. p16, p21, γH2AX, IL-1ß, and TNFα mRNA expression levels were higher in the gingiva of the AC group than in the YC group, while this enhanced expression was significantly suppressed in AE gingiva. NF-κB p65 expression was high in the AC group but was strongly suppressed in the AE group. We induced senescence in cultured human gingival fibroblasts using H2O2 and lipopolysaccharide before erythritol treatment, which reduced elevated senescence-related marker (p16, p21, SA-ß-gal, IL-1ß, and TNFα) expression levels. Knockdown of PFK or PGAM promoted p16 and p21 mRNA expression, but erythritol subsequently rescued pyruvate production. Overall, intraoral erythritol administration may prevent age-related oral mucosal diseases.

Outcomes and a prognostic classifier in patients with microsatellite instability-high metastatic gastric cancer receiving PD-1 blockade.

BACKGROUND: Subgroup analyses of randomized trials suggest the superiority of immune checkpoint inhibitor-based therapy over chemotherapy in patients with mismatch-repair deficient (dMMR) and/or microsatellite instability-high (MSI-high) advanced gastric or gastroesophageal junction adenocarcinoma. However, these subgroups are small and studies examining prognostic features within dMMR/MSI-high patients are lacking. METHODS: We conducted an international cohort study at tertiary cancer centers and collected baseline clinicopathologic features of patients with dMMR/MSI-high metastatic or unresectable gastric cancer treated with anti-programmed cell death protein-1 (PD-1)-based therapies. The adjusted HRs of variables significantly associated with overall survival (OS) were used to develop a prognostic score. RESULTS: One hundred and thirty patients were included. At a median follow-up of 25.1 months, the median progression-free survival (PFS) was 30.3 months (95% CI: 20.4 to NA) and 2-year PFS rate was 56% (95% CI: 48% to 66%). Median OS was of 62.5 months (95% CI: 28.4 to NA) and 2-year OS rate was 63% (95% CI: 55% to 73%). Among the 103 Response Evaluation Criteria in Solid Tumors-evaluable patients, objective response rate was 66% and disease control rate 87% across lines of therapy. In the multivariable models, Eastern Cooperative Oncology Group Performance Status of 1 or 2, non-resected primary tumor, presence of bone metastases and malignant ascites were independently associated with poorer PFS and OS. These four clinical variables were used to build a three-category (ie, good, intermediate, and poor risk) prognostic score. Compared with patients with good risk, patients with intermediate risk score had numerically inferior PFS and OS (2-year PFS rate: 54.3% versus 74.5%, HR 1.90, 95% CI: 0.99 to 3.66; 2-year OS rate: 66.8% versus 81.2%, HR 1.86, 95% CI: 0.87 to 3.98), whereas patients with poor risk score had significantly inferior PFS and OS (2-year PFS rate: 10.6%, HR 9.65, 95% CI: 4.67 to 19.92; 2-year OS rate: 13.3%, HR 11.93, 95% CI: 5.42 to 26.23). CONCLUSIONS: Overall outcomes with anti-PD-1-based therapies are favorable in MSI-high gastroesophageal adenocarcinomas. However, within this overall favorable subgroup a more accurate prognostication using baseline clinical characteristics might identify patients at higher risk of rapid disease progression who may deserve intensified immunotherapy combination strategies.