Evidence and Future Perspectives for Neoadjuvant Therapy for Resectable and Borderline Resectable Pancreatic Cancer: A Scoping Review.

Pancreatic cancer (PC) is a lethal disease that requires innovative therapeutic approaches to enhance the survival outcomes. Neoadjuvant treatment (NAT) has gained attention for resectable and borderline resectable PC, offering improved resection rates and enabling early intervention and patient selection. Several retrospective studies have validated its efficacy. However, previous studies have lacked intention-to-treat analyses and appropriate resectability classifications. Randomized comparative trials may help to enhance the clinical applicability of evidence. Therefore, after searching the MEDLINE database, this scoping review presents a comprehensive summary of the evidence from published (n = 14) and ongoing (n = 12) randomized Phase II and III trials. Diverse regimens and their outcomes were explored for both resectable and borderline resectable PC. While some trials have supported the efficacy of NAT, others have demonstrated no clear survival benefits for patients with resectable PC. The utility of NAT has been confirmed in patients with borderline resectable PC, but the optimal regimens remain debatable. Ongoing trials are investigating novel regimens, including immunotherapy, thereby highlighting the dynamic landscape of PC treatment. Studies should focus on biomarker identification, which may enable precision in oncology. Future endeavors aim to refine treatment strategies, guided by precision oncology.

Identifying the Trends of Urinary microRNAs within Extracellular Vesicles for Esophageal Cancer.

Background: The advancement of multidisciplinary treatment has increased the need to develop tests to monitor tumor burden during treatment. We herein analyzed urinary microRNAs within extracellular vesicles from patients with esophageal squamous cell carcinoma (ESCC) and normal individuals using a microarray. Methods: Patients with advanced ESCC who underwent esophagectomy (A), endoscopic submucosal resection (ESD) (B), and healthy donors (C) were included. Based on microRNA expression among the groups (Analysis 1), microRNAs with significant differences between groups A and C were selected (Analysis 2). Of these candidates, microRNAs in which the change between A and C was consistent with the change between B and C were selected for downstream analysis (Analysis 3). Finally, microRNA expression was validated in patients with recurrence from A (exploratory analysis). Results: For analysis 1, 205 microRNAs were selected. For Analyses 2 and 3, the changes in 18 microRNAs were consistent with changes in tumor burden as determined by clinical imaging and pathological findings. The AUC for the detection of ESCC using 18 microRNAs was 0.72. In exploratory analysis, three of eighteen microRNAs exhibited a concordant trend with recurrence. Conclusions: The current study identified the urinary microRNAs which were significantly expressed in ESCC patients. Validation study is warranted to evaluate whether these microRNAs could reflect tumor burden during multidisciplinary treatment for ESCC.

Effects of the COVID-19 pandemic on short-term postoperative outcomes for colorectal perforation: A nationwide study in Japan based on the National Clinical Database.

Aim: Possible negative effects of the COVID-19 pandemic on short-term postoperative outcomes for colorectal perforation in Japan were examined in this study. Methods: The National Clinical Database (NCD) is a large-scale database including more than 95% of surgical cases in Japan. We analyzed 13 107 cases of colorectal perforation from 2019 to 2021. National data were analyzed, and subgroup analyses were conducted for subjects in prefectures with high infection levels (HILs) and metropolitan areas (Tokyo Met. and Osaka Pref.). Postoperative 30-day mortality, surgical mortality, and postoperative complications (Clavien-Dindo grade ≥3) were examined. Months were considered to have significantly high or low mortality or complication rates, if the 95% confidence interval (CI) of the standardized mortality (morbidity) ratio (SMR) does not contain 1. Results: In the NCD, postoperative 30-day mortality occurred in 1371 subjects (10.5%), surgical mortality in 1805 (13.8%), and postoperative complications in 3950 (30.1%). Significantly higher SMRs were found for 30-day mortality in November 2020 (14.6%, 1.39 [95% CI: 1.04-1.83]) and February 2021 (14.6%, 1.48 [95% CI: 1.10-1.96]), and for postoperative complications in June 2020 (37.3%, 1.28 [95% CI: 1.08-1.52]) and November 2020 (36.4%, 1.21 [95% CI: 1.01-1.44]). The SMRs for surgical mortality were not significantly high in any month. In prefectures with HILs and large metropolitan areas, there were few months with significantly higher SMRs. Conclusions: The COVID-19 pandemic had limited negative effects on postoperative outcomes in patients with colorectal perforation. These findings suggest that the emergency system for colorectal perforation in Japan was generally maintained during the pandemic.

Presurgical mild anemia is a risk factor for severe postoperative complications of rectal cancer surgery: A Japanese nationwide retrospective cohort study.

Background: Anemia has negative effects on long-term outcomes of rectal cancer patients; however, its status as a risk factor for severe complications is disputed. Perioperative risks may differ based on the severity of pre-surgical anemia; nonetheless, no previous study has investigated these differences. This study identified risks of severe postoperative complications in rectal cancer patients based on severity of their pre-surgical anemia. Materials and Methods: This study enrolled patients who underwent low anterior resection for rectal cancer and were registered in the Japanese National Clinical Database (NCD) between 2017 and 2019. Anemia severity was categorized into three levels: mild, moderate, and severe. A logistic regression model was applied to calculate the risk-adjusted odds ratio (OR) of severe complications after surgery. Results: This study analyzed a cohort of 51 765 rectal cancer patients who underwent low anterior resection. Results showed that severe complications occurred in 10.9% of patients and were significantly more frequent in patients with anemia (13.6%) than those with normal hemoglobin levels (9.2%). Risk-adjusted ORs of severe complications in the severe, moderate, and mild anemia groups versus the normal group for males were 1.19 (95% confidence interval [CI]: 0.89-1.58), 1.47 (1.34-1.62), and 1.21 (1.12-1.31), respectively. Those for females were 1.39 (0.90-2.15), 1.64 (1.37-1.97), and 1.36 (1.16-1.58), respectively. Conclusions: According to this large cohort study, pre-surgical anemia significantly increases the risk of severe postoperative complications in rectal cancer patients. Even mild anemia presents a significant risk.

Investigation of the impact of COVID-19 on postoperative outcomes using a nationwide Japanese database of patients undergoing laparoscopic distal gastrectomy and low anterior resection for gastric cancer and rectal cancer.

Background: The COVID-19 outbreak made conventional medical care impossible, forcing changes in both healthcare providers and patients. In Japan, COVID-19 infection began spreading in earnest in 2020 and exploded in 2021. There was concern that the medical impact of COVID-19 in 2021 would differ from that in 2020. We aimed to clarify the impact of COVID-19 on mortality and anastomotic leakage in laparoscopic surgery for gastric cancer and rectal cancer in Japan using the National Clinical Database (NCD). Methods: We collected data from patients who underwent laparoscopic distal gastrectomy (LDG) and laparoscopic low anterior resection (LLAR) from January 2018 to December 2021 from the NCD, a web-based surgical registration system in Japan. The number of surgical cases, monthly incidence of mortality and morbidity (anastomotic leakage), standardized mortality ratio (SMR), and standardized morbidity-leakage ratio (SMLR [ratio of observed patients to expected patients calculated using the risk calculator established in the NCD]) were evaluated. Results: The numbers of LDG and LLAR cases continued to decline in the first year of the pandemic in 2020 and were as low in 2021 as in 2020. Although the numbers of robot-assisted LDG and LLAR cases increased, the growth rate was lower than the rate of increase prior to the pandemic. Mortality and anastomotic leakage, two of the most important complications, as assessed by SMR and SMLR, did not worsen during the pandemic in comparison to the pre-pandemic period. Conclusions: Laparoscopic surgeries were performed safely in Japan and were not affected by the COVID-19 pandemic.

Multiple asynchronous recurrence as a predictive factor for refractoriness against locoregional and surgical therapy in patients with intermediate-stage hepatocellular carcinoma.

Development of subclassification of intermediate-stage hepatocellular carcinoma (HCC) by treatment suitability is in demand. We aimed to identify predictors that define treatment refractoriness against locoregional(transarterial chemoembolization(TACE) or thermal ablation) and surgical therapy. This multicenter retrospective study enrolled 1167 HCC patients between 2015 and 2021. Of those, 209 patients were initially diagnosed with intermediate-stage HCC. Treatment refractoriness was defined as clinical settings that meets the following untreatable progressive conditions by TACE (1) 25% increase of intrahepatic tumor, (2) transient deterioration to Child-Pugh class C, (3) macrovascular invasion or extrahepatic spread, within one year. We then analyzed factors contributing to treatment refractoriness. The Child-Pugh score/class, number of tumors, infiltrative radiological type, and recurrence were significant factors. Focusing on recurrence as a predictor, median time to untreatable progression (TTUP) was 17.2 months in the recurrence subgroup whereas 35.5 months in the initial occurrence subgroup (HR, 2.06; 95% CI, 1.44-2.96; P = 0.001). Median TTUP decreased in cases with more later times of recurrence (3-5 recurrences, 17.3 months; ≥ 6 recurrences, 7.7 months). Recurrence, even more at later times, leads to increased treatment refractoriness. Early introduction of multidisciplinary treatment should be considered against HCC patients after multiple recurrent episodes.

Nivolumab plus chemotherapy or ipilimumab versus chemotherapy in patients with advanced esophageal squamous cell carcinoma (CheckMate 648): 29-month follow-up from a randomized, open-label, phase III trial.

BACKGROUND: First-line nivolumab plus chemotherapy and nivolumab plus ipilimumab both demonstrated significant overall survival (OS) benefit versus chemotherapy in previously untreated patients with advanced esophageal squamous cell carcinoma (ESCC) in the CheckMate 648 trial, leading to approvals of both nivolumab-containing regimens in many countries. We report longer-term follow-up data. METHODS: This open-label, phase III trial (NCT03143153) enrolled adults with previously untreated, unresectable, advanced, recurrent, or metastatic ESCC. Patients were randomized 1:1:1 to nivolumab plus chemotherapy, nivolumab plus ipilimumab, or chemotherapy. Primary endpoints were OS and progression-free survival (PFS) by blinded independent central review. Hierarchical testing was performed first in patients with tumor cell programmed death ligand 1 (PD-L1) expression of ≥1% and then in the overall population. RESULTS: A total of 970 patients were randomly assigned. After 29 months of minimum follow-up, nivolumab plus chemotherapy continued to demonstrate improvement in OS versus chemotherapy (hazard ratio [HR] = 0.59 [95% CI: 0.46-0.76]) in patients with tumor cell PD-L1 expression of ≥1% and in the overall population (HR = 0.78 [95% CI: 0.65-0.93]) and with nivolumab plus ipilimumab versus chemotherapy (HR = 0.62 [95% CI: 0.48-0.80]) in patients with tumor cell PD-L1 expression of ≥1% and in the overall population (HR = 0.77 [95% CI: 0.65-0.92]). In patients with tumor cell PD-L1 expression of ≥1%, nivolumab plus chemotherapy demonstrated PFS benefit versus chemotherapy (HR = 0.67 [95% CI: 0.51-0.89]); PFS benefit was not observed with nivolumab plus ipilimumab versus chemotherapy (HR = 1.04 [95% CI: 0.79-1.36]). Among all treated patients (n = 936), Grade 3-4 treatment-related adverse events were reported in 151 (49%, nivolumab plus chemotherapy), 105 (32%, nivolumab plus ipilimumab), and 110 (36%, chemotherapy) patients. CONCLUSIONS: Nivolumab plus chemotherapy and nivolumab plus ipilimumab continued to demonstrate clinically meaningful OS benefit versus chemotherapy with no new safety signals identified with longer follow-up, further supporting use as first-line standard treatment options for patients with advanced ESCC.

Japanese Classification of Esophageal Cancer, 12th Edition: Part I.

This is the first half of English edition of Japanese Classification of Esophageal Cancer, 12th Edition that was published by the Japan Esophageal Society in 2022.

Short-term outcomes after liver resection with vascular reconstruction: Results from a study with the National Clinical Database of Japan.

BACKGROUND: Although curative resection with vascular reconstruction improves the prognosis of blood-invading locally advanced hepatobiliary tumors, the mortality and morbidity of the procedure remains unclear. This study aimed to clarify the risk factors associated with mortality and morbidity in patients undergoing liver resection with vascular reconstruction. METHODS: This retrospective observational study included 1215 patients undergoing hepatectomy of more than one section with vascular reconstruction, except for left lateral sectionectomy registered in the National Clinical Database (NCD) between 2015 and 2019. The rates of surgical mortality and relevant clinical factors were evaluated. RESULTS: Among the four types of vascular reconstruction, portal venous reconstruction was frequently performed in 724 patients (59.6% of the enrolled patients). Surgical mortality was 8.1%. Patients with hepatic artery reconstruction had the highest surgical mortality rate of 15.8%. In other types of reconstruction, surgical mortality was 9.1% in the portal vein, 5.2% in inferior vena cava, and 4.9% in hepatic vein. Factors significantly associated with surgical mortality include age, sex (male), preoperative comorbidity (American Society of Anesthesiologists grade >3, respiratory distress, diabetes, preoperative pneumonia, weight loss, and obstructive jaundice), poorer liver functional reserve (indocyanine green retention rate at 15 min and prothrombin time/international normalized ratio >1.1) and accompanying biliary reconstruction. CONCLUSIONS: The NCD revealed the detailed status of liver resection combined with vascular reconstruction in Japan. Based on the results of this analysis, understanding the factors that influence the outcome and postoperative course of each procedure will provide patients with accurate information and opportunities to improve future outcomes.

Preoperative predictive factors for positive peritoneal cytology results in patients with pancreatic ductal adenocarcinomas: a retrospective study.

BACKGROUND: The clinical importance of positive peritoneal cytology results in patients with pancreatic ductal adenocarcinomas remains controversial. We evaluated the prognosis of these patients and the predictive preoperative risk factors for positive peritoneal cytology results. METHODS: We retrospectively reviewed patients who underwent curative-intent surgery at our institution between May 2010 and June 2020. Preoperative risk factors for positive peritoneal cytology results were identified using logistic regression analysis. A scoring model was constructed using the total number of significant independent predictors for positive peritoneal cytology results. RESULTS: Of 233 patients, 18 (7.7%) had positive peritoneal cytology results. The recurrence-free survival and cancer-specific survival were markedly worse in patients with positive peritoneal cytology results than in those with negative peritoneal cytology results (recurrence-free survival: 6.0 months vs. 16.6 months, p = 0.050; cancer-specific survival: 19.4 months vs. 47.5 months, p = 0.034). Tumor location (odds ratio: 3.760, 95% confidence interval: 1.099-11.818, p = 0.023), tumor size > 25 mm (odds ratio: 3.410, 95% confidence interval: 1.031-11.277, p = 0.046), preoperative serosal invasion (odds ratio: 5.193, 95% confidence interval: 1.099-24.531, p = 0.038), and preoperative carcinoembryonic antigen level > 5.6 ng/mL (odds ratio: 3.816, 95% confidence interval: 1.248-10.667, p = 0.019) were identified as significant independent predictive factors. Our predictive model's optimal cutoff and positive predictive values for positive peritoneal cytology results were 3 and 27.9%, respectively. CONCLUSIONS: The indications for curative-intent surgery should be considered carefully in patients with high-risk factors for positive peritoneal cytology results.

Factors affecting motivation for receiving a booster dose of the COVID-19 vaccine among Japanese university students and staff: a cross-sectional questionnaire survey.

Understanding the factors that influence people's decisions regarding vaccination is essential to promote vaccination. We aimed to clarify the motivations for receiving booster vaccines. We conducted a paper-based questionnaire distributed during January-February 2022 involving students and faculty staff who received the first COVID-19 vaccination at the mass vaccination program during June-September 2021 at Keio University. A total of 1725 participants were enrolled, and all completed the survey. Among these, 64.9% reported a significant adverse event (AEs) affecting daily life after the second vaccine. "Fear of severe COVID-19 illness" (72.6%) was the most common reason for getting vaccinated, followed by "concern of infecting others" (68.4%) and "fear of COVID-19 infection itself" (68.3%). Television emerged as the most influential source of information (80%), followed by university information (50.2%) and social networking sites (42.8%). Multivariate analysis revealed "fear of severe COVID-19 illness", "fear of COVID-19 infection itself", and "trust in the efficacy and safety of the vaccines in general" were significantly correlated with willingness to receive paid vaccinations. The severity of AEs and source of information were not related to participants' willingness to receive booster vaccinations. Participants with positive reasons for vaccination were more likely to accept a third dose.

Japanese Classification of Esophageal Cancer, 12th Edition: Part II.

This is the second half of English edition of Japanese Classification of Esophageal Cancer, 12th Edition that was published by the Japan Esophageal Society in 2022.

Requirements for hospitals in Japan to have low operative mortality and failure-to-rescue rates.

Aim: We explored institutional factors in Japan associated with lower operative mortality and failure-to-rescue (FTR) rates for eight major gastrointestinal procedures. Methods: A 22-item online questionnaire was sent to 2119 institutional departments (IDs) to examine the association between institutional factors and operative mortality and FTR rates. IDs were classified according to the number of annual surgeries, board certification status, and locality. In addition, the top 20% and bottom 20% of IDs were identified based on FTR rates and matched with the results of the questionnaire survey. Factors associated with operative mortality were selected by multivariate analysis. Results: Of the 1083 IDs that responded to the questionnaire, 568 (213 382 patients) were included in the analysis. Operative morbidity, operative mortality, and FTR rates in the top 20% and bottom 20% of IDs were 13.1% and 8.4% (p < 0.001), 0.52% and 4.3% (p < 0.001), and 4.0% and 51.2% (p < 0.001), respectively. Based on the patients' background characteristics, the top 20% of IDs handled more advanced cases. No significant difference in locality was seen between better or worse hospital FTR rates, but fewer esophagectomies, hepatectomies, and pancreatoduodenectomies were performed in depopulated areas. Six items were found to be associated with operative mortality by multivariate logistic analysis. Only 50 (8.8%) IDs met all five factors related to better FTR rates. Conclusions: The present findings indicate that several hospital factors surrounding surgical treatment, characterized by abundant human resources, are closely related to better postoperative recovery from severe complications.

Tele-proctoring for minimally invasive surgery across Japan: An initial step toward a new approach to improving the disparity of surgical care and supporting surgical education.

Aim: The aim of this study was to verify the clinical feasibility of tele-proctoring using our ultra-low latency communication system with shared internet access. Methods: Connections between two multiple remote locations at various distances were established through the TELEPRO® tele-proctoring system. The server records the latency between the two locations for tele-proctoring using the annotations. Questionnaires were administered to the surgeons, assistants, and medical staff. Respondents rated the quickness and quality of communication in terms of latency and disturbances in the audio, video, and usefulness of the live telestrations with annotation. Results: Seven hospitals tele-proctored with Sapporo Medical University between January 2021 and September 2022. The median latency of annotation between the two locations ranged from 24.5 to 48.5 ms. No major technological problems occurred, such as streaming interruption, loss of video or audio, poor resolution. The video encoding time was 10 ms, and its decoding time was 0.8 ms. The total latency positively correlated with the distance between two locations (R = 0.55, p < 0.01). The quality of communication regarding latency, disturbance, and surgical education with intraoperative annotative instructions showed similar trends, with perfectly fine being the most common response. No significant differences in surgical quality, educational effect, or social impact were observed between the latency ≥30 and <30 ms groups for whether the size of latency affects surgical education. Conclusion: The feasibility of the tele-proctoring system is expected to be a sustainable approach to help education for young surgeons and surgical supports in rural areas, thereby reducing disparities in health care.

POFUT1 and PLAGL2 are characteristic markers of mucinous colorectal cancer associated with MUC2 expression.

Colorectal mucinous adenocarcinoma (MAC) is one of the most lethal histological types of colorectal cancer, and its mechanism of development is not well understood. In this study, we aimed to clarify the molecular characteristics of MAC via in silico analysis using The Cancer Genome Atlas database. The expression of genes on chromosome 20q (Chr20q) was negatively associated with the expression of MUC2, which is a key molecule that can be used to distinguish between MAC and nonmucinous adenocarcinoma (NMAC). This was consistent with a significant difference in copy number alteration of Chr20q between the two histological types. We further identified 475 differentially expressed genes (DEGs) between MAC and NMAC, and some of the Chr20q genes among the DEGs are considered to be pivotal genes used to define MAC. Both in vitro and in vivo analysis showed that simultaneous knockdown of POFUT1 and PLAGL2, both of which are located on Chr20q, promoted MUC2 expression. Moreover, these genes were highly expressed in NMAC but not in MAC according to the results of immunohistological studies using human samples. In conclusion, POFUT1 and PLAGL2 are considered to be important for defining MAC, and these genes are associated with MUC2 expression.

Proton Pump Inhibitors and Cyclin-Dependent Kinase 4/6 Inhibitors in Patients With Breast Cancer.

BACKGROUND: Proton pump inhibitors (PPIs) reduce the bioavailability of several anticancer drugs. The impact of PPIs co-administered with cyclin-dependent kinase 4 and 6 inhibitors is controversial. We aimed to clarify whether the concomitant use of PPIs impacts palbociclib and abemaciclib effectiveness in breast cancer treatment. PATIENTS AND METHODS: This multicenter, retrospective, observational study, conducted across 4 medical institutions in Japan, consecutively included patients with endocrine-resistant metastatic breast cancer, receiving palbociclib or abemaciclib between December 2017 and August 2022. Propensity score-matched analyses were performed. Treatment efficacy and safety with and without PPIs were compared. Progression-free survival and overall survival were estimated using the Kaplan-Meier method and compared using a log-rank test. A Cox proportional hazards model was used to estimate the hazard ratio. RESULTS: The study included 240 patients. After 1:1 matching, 112 patients were treated with and without PPIs. The median progression-free survival period was 1.2 years in the PPI group and 1.3 years in the non-PPI group (hazard ratio, 1.19; 95% CI, 0.70-2.02). The median overall survival period was 3.6 years in the PPI group, whereas it was not reached in the non-PPI group (hazard ratio, 1.23; 95% CI, 0.61-2.47). Consistent results were obtained for subgroups receiving palbociclib (n = 177) and abemaciclib (n = 63) without propensity score matching. Adverse event incidence and severity were similar in both groups. CONCLUSION: The effectiveness of cyclin-dependent kinase 4/6 inhibitors is unlikely to be affected by concomitant PPI use. Future prospective pharmacokinetic studies are warranted.

Protective Effects of Hydrogen Gas Inhalation for Hindlimb Ischaemia-Reperfusion Injury in a Mouse Model.

OBJECTIVE: Ischaemia-reperfusion (I/R) injury is a severe post-operative complication that triggers an inflammatory response and causes severe damage. Hydrogen gas has anti-oxidant and anti-apoptotic properties and has been shown to be safe in humans. The study aimed to investigate whether hydrogen gas protects against skeletal muscle I/R injury. METHODS: Experimental basic research using mice. A total of 160 eight to 10 week old albino laboratory bred strain of house mice (25.8 ± 0.68 g) were used in this study. The mice were cable tied to the hindlimb under anaesthesia and then placed in an anaesthesia box filled with air and 2% isoflurane (control group); 80 mice were additionally subjected to 1.3% hydrogen gas in this mix (hydrogen group). After two hours, the cable ties were removed to initiate reperfusion, and hydrogen inhalation lasted for six hours in the hydrogen group. After six hours, the mice were taken out of the box and kept in cages under standard conditions until time for observation at 16 different time points after reperfusion: zero, two, four, six, eight, and 10 hours and one, two, three, four, five, six, seven, 14, 21, and 28 days. Five mice were sacrificed using excess anaesthesia at each time point, and the bilateral hindlimb tissues were harvested. The inflammatory effects of the I/R injury were assessed by evaluating serum interleukin-6 concentrations using enzyme linked immunosorbent assay, as well as histological and immunohistochemical analyses. Untreated mice with I/R injury were used as controls. RESULTS: Hydrogen gas showed protective effects associated with a reduction in inflammatory cell infiltration (neutrophils, macrophages, and lymphocytes), a reduced area of damaged muscle, maintenance of normal muscle cells, and replacement of damaged muscle cells with neoplastic myocytes. CONCLUSION: Inhalation of hydrogen gas had a protective effect against hindlimb I/R injury in mice, in part by reducing inflammatory cell infiltration and in part by preserving normal muscle cells.

PRMT1 Sustains De Novo Fatty Acid Synthesis by Methylating PHGDH to Drive Chemoresistance in Triple-Negative Breast Cancer.

Triple-negative breast cancer (TNBC) chemoresistance hampers the ability to effectively treat patients. Identification of mechanisms driving chemoresistance can lead to strategies to improve treatment. Here, we revealed that protein arginine methyltransferase-1 (PRMT1) simultaneously methylates D-3-phosphoglycerate dehydrogenase (PHGDH), a critical enzyme in serine synthesis, and the glycolytic enzymes PFKFB3 and PKM2 in TNBC cells. 13C metabolic flux analyses showed that PRMT1-dependent methylation of these three enzymes diverts glucose toward intermediates in the serine-synthesizing and serine/glycine cleavage pathways, thereby accelerating the production of methyl donors in TNBC cells. Mechanistically, PRMT1-dependent methylation of PHGDH at R54 or R20 activated its enzymatic activity by stabilizing 3-phosphoglycerate binding and suppressing polyubiquitination. PRMT1-mediated PHGDH methylation drove chemoresistance independently of glutathione synthesis. Rather, activation of the serine synthesis pathway supplied α-ketoglutarate and citrate to increase palmitate levels through activation of fatty acid synthase (FASN). Increased palmitate induced protein S-palmitoylation of PHGDH and FASN to further enhance fatty acid synthesis in a PRMT1-dependent manner. Loss of PRMT1 or pharmacologic inhibition of FASN or protein S-palmitoyltransferase reversed chemoresistance in TNBC. Furthermore, IHC coupled with imaging MS in clinical TNBC specimens substantiated that PRMT1-mediated methylation of PHGDH, PFKFB3, and PKM2 correlates with chemoresistance and that metabolites required for methylation and fatty acid synthesis are enriched in TNBC. Together, these results suggest that enhanced de novo fatty acid synthesis mediated by coordinated protein arginine methylation and protein S-palmitoylation is a therapeutic target for overcoming chemoresistance in TNBC. SIGNIFICANCE: PRMT1 promotes chemoresistance in TNBC by methylating metabolic enzymes PFKFB3, PKM2, and PHGDH to augment de novo fatty acid synthesis, indicating that targeting this axis is a potential treatment strategy.