Immature stroma and high infiltration of CD15+ cells are predictive markers of poor prognosis in different subsets of patients with pancreatic cancer.

Preoperative treatment is commonly carried out for borderline resectable pancreatic ductal adenocarcinoma (PDAC). However, the relationship between the combination of immune cells in the tumor microenvironment and their intratumoral heterogeneity along with their association with histological findings remains unclear, especially in patients receiving preoperative chemotherapy. We aimed to explore the therapeutic strategies for patients with PDAC with poor prognosis after receiving chemotherapy based on histological and immunological microenvironmental classifications. We investigated the correlation between the prognosis and histological immune microenvironmental factors of patients who initially underwent surgery (n = 100) and were receiving gemcitabine plus nab-paclitaxel (GEM + nabPTX) as preoperative chemotherapy (n = 103). Immune profiles were generated based on immune cell infiltration into the tumor, and their correlation with patient outcomes and histological features was analyzed. Tumor-infiltrating neutrophils (TINs) were identified as independent poor prognostic factors using multivariate analysis in both surgery-first and preoperative chemotherapy groups. The patients were further classified into four groups based on immune cell infiltration into the tumor. Patients with high CD15 infiltration into the tumor and immature stroma at the cancer margins showed the worst prognosis in the preoperative chemotherapy group. The analysis of mRNA expression and immunohistochemical features revealed that CXCR2, the receptor for CXCL8, was correlated with disease-free and overall survival. We inferred that patients with immature stroma at the margins and high infiltration of CD15+ neutrophils within the tumor showed the worst prognosis and they could particularly benefit from treatment with inhibitors targeting CXCR2 or CXCL8.

Prognostic value of nuclear morphometry in myxoid liposarcoma.

Myxoid liposarcoma (MLS) accounts for 20%-30% of liposarcoma and the round cell component (RCC) is believed to be a specific poor prognostic factor. However, the RCC assessment criteria are vaguely defined and, therefore, are inconsistently employed by pathologists. In this study, we modified and applied two established grading systems to evaluate nuclear atypia (namely, the World Health Organization/International Society of Urological Pathology and the Fuhrman grading in renal cell carcinoma) in 64 MLS cases. Detailed software-based assessments of the morphology and the cellularity were performed. DNA mutation analysis, comprehensive mRNA expression analysis, and immunohistochemistry were also performed. Our findings revealed that the high-nuclear-grade group according to the modified Fuhrman grading system exhibited a significantly poor disease-free survival (hazard ratio: 4.43; 95% confidence interval: 0.9-22.6; p = 0.047). On the other hand, the cellularity was significantly higher in the modified Fuhrman high-grade group (p = 0.010 at the percentage of the hypercellular area; p = 0.003 at the maximum cell density) but did not qualify per se as a poor prognostic factor in the survival analyses. Furthermore, the modified Fuhrman high-grade group significantly expressed the cell cycle-related genes (such as FOXM1, PLK1, and CDK1). In conclusion, our analyses suggest that an evaluation focusing on nuclear morphology (rather than on cellular density) can be more reliable in predicting the MLS prognosis.

Clinicopathologic Features and Genetic Alterations in Mixed-Type Ampullary Carcinoma.

Mixed-type ampullary carcinoma is a subtype that combines intestinal-type (I-type) and pancreatobiliary-type (PB-type) lesions, but few studies have examined its clinicopathologic features and genetic alterations. The differences in genetic alterations between mixed type and other subtypes, as well as the genetic differences between I-type and PB-type lesions in the mixed type, remain unclear. In this study, we compared the clinicopathologic features and prognosis of 110 ampullary carcinomas classified by hematoxylin and eosin and immunohistochemical staining as follows: 63 PB-type, 35 I-type, and 12 mixed-type carcinomas. A comparative analysis of genetic mutations by targeted sequencing of 24 genes was also performed in 3 I-type cases, 9 PB-type cases, and I and PB-type lesions of 6 mixed-type cases. The mixed subtype had a poorer prognosis than the other subtypes, and there was also a similar tendency in the adjuvant group (n = 22). A total of 49 genetic mutations were detected in all 18 lesions for which genetic alteration was analyzed. No genetic mutations specific to the mixed type were found, and it was not possible to determine genetically whether the mixed type had originally been I or PB type. However, 5 of 6 cases had mutations common to both I and PB-type lesions, and additional mutations were found only in either I or PB-type lesions. In support of this, the mixed type more frequently exhibited genetic heterogeneity intratumorally than the other subtypes. Mixed-type tumors are histologically, immunohistochemically, and genetically heterogeneous, and this heterogeneity is associated with poor prognosis and may affect treatment resistance.

Ampullary Neuroendocrine Neoplasm: Clinicopathological Characteristics and Novel Endoscopic Entity.

BACKGROUND: Neuroendocrine neoplasms of the ampulla of Vater (ampullary NEN) have features of both gastrointestinal and pancreato-biliary (PB) NEN. However, the limited number of studies examining ampullary NEN makes it difficult to clarify their unique characteristics. This study aimed to elucidate the clinical characteristics of ampullary NEN. METHODS: We enrolled 162 patients with PB-NEN diagnosed at Kyushu University Hospital between 2011 and 2020. Clinical features, pathological diagnoses, treatments, and prognoses were retrospectively analyzed. We also compared ampullary NEN with pancreatic NEN (PanNEN). RESULTS: We analyzed 10 ampullary NEN cases and 149 PanNEN cases. The ampullary NEN cases consisted of 4 cases of neuroendocrine tumor Grade 1 (NET G1), 1 NET G2 (Grade 2), and 5 neuroendocrine carcinomas (NECs). The incidences of NEC and cholangitis were significantly higher in ampullary NEN than in PanNEN. All ampullary NETs had a submucosal tumor-like appearance, as identified by endoscopic ultrasound-guided fine needle aspiration. We treated small NET G1 (<10 mm) with endoscopic papillectomy and large NET G1 with pancreaticoduodenectomy. There were no cases of recurrence after resection. All ampullary NECs presented with the characteristic endoscopic finding of a "crater sign" similar to deep-mining ulcers seen in gastric malignant lymphoma. Four cases underwent surgical resection, and 1 case was unresectable. Two patients who underwent multidisciplinary treatment were maintained without recurrence for over 2 years. CONCLUSIONS: Endoscopic findings showed identifiable distinctions between ampullary NETs and NECs.

[Hypokalemia and potassium replacement therapy in allogeneic hematopoietic stem cell transplantation].

Hypokalemia is common in allogeneic hematopoietic stem cell transplantation (allo-HCT) patients and is associated with non-relapse mortality (NRM). Therefore, it is extremely important to replace potassium adequately. We evaluated the safety and efficacy of potassium replacement therapy by retrospectively analyzing the incidence and severity of hypokalemia in 75 patients who received allo-HCT at our institution. 75% of patients developed hypokalemia during the allo-HSCT, and 44% of patients had grade 3-4 levels of hypokalemia. NRM was significantly higher in patients with grade 3-4 hypokalemia than in patients without severe hypokalemia (one-year NRM: 30% vs 7%, p=0.008). Although 75% of the patients required potassium replacement that exceeded the range of potassium chloride solutions package inserts in Japan, we did not experience any adverse events associated with hyperkalemia. Our current observations suggested that the Japanese package insert for potassium solution injection should be revised for potassium needs.

Histological and immunohistochemical features and genetic alterations in the malignant progression of giant cell tumor of bone: a possible association with TP53 mutation and loss of H3K27 trimethylation.

In rare cases, giant cell tumor of bone (GCTB) can undergo primary or secondary malignant transformation to malignant giant cell tumor of bone (MGCTB), but the details of the molecular alterations are still unclear. The present study aimed to elucidate the clinicopathologic and molecular features of MGCTBs based on immunohistochemistry, fluorescence in situ hybridization (FISH) and next generation sequencing (NGS) of nine MGCTBs (five primary and four secondary). Seven (78%) of 9 MGCTBs were immunohistochemically positive for H3.3 G34W. In two (22%) patients, although GCTB components were focally or diffusely positive for H3.3 G34W, their malignant components were entirely negative for H3.3 G34W, which was associated with heterozygous loss of H3F3A by FISH. NGS on four MGCTBs revealed pathogenic mutations in TP53 (n = 3), EZH2 (n = 1) and several other genes. Immunohistochemical analysis of the nine MGCTBs confirmed the p53 nuclear accumulation (n = 5) and loss of H3K27me3 expression (n = 3) and showed that they were mutually exclusive. In addition, four (80%) of five cases of pleomorphic or epithelioid cell-predominant MGCTBs were positive for p53, while three (75%) of four cases of spindle cell-predominant MGCTBs were negative for trimethylation at lysine 27 of histone 3 (H3K27me3). The results suggested that p53 alteration and dysfunction of histone methylation as evidenced by H3K27me3 loss may play an important role in the malignant progression of GCTB, and might contribute to the phenotype-genotype correlation in MGCTB. The combined histologic, immunohistochemical and molecular information may be helpful in part for the diagnosis of challenging cases.

Concomitant Intraductal Papillary Mucinous Neoplasm in Pancreatic Ductal Adenocarcinoma Is an Independent Predictive Factor for the Occurrence of New Cancer in the Remnant Pancreas.

OBJECTIVE: To determine the factors predicting the subsequent development of pancreatic ductal adenocarcinoma in remnant pancreas (PDAC-RP) after partial pancreatectomy for PDAC. SUMMARY BACKGROUND DATA: PDAC-RP after partial pancreatectomy for PDAC is currently not so rare because of improved prognosis of PDAC patients due to recent advances in surgical techniques and adjuvant therapy. However, the predictive factors related to PDAC-RP remain unknown. METHODS: We retrospectively reviewed the clinicopathological data of a consecutive series of 379 patients with PDAC treated by partial pancreatectomy between 1992 and 2015; 14 patients (3.69%) had PDAC-RP. Clinicopathological variables were compared between PDAC-RP and non-PDAC-RP. RESULTS: In univariate analysis, concomitant intraductal papillary mucinous neoplasm (IPMN) (P = 0.0005), cancer location (body/tail) (P = 0.0060), and lower T factor in UICC (P = 0.0039) were correlated with PDAC-RP development. Multivariate analysis revealed concomitant IPMN (P = 0.0135) to be an independent predictive factor for PDAC-RP. PDAC concomitant with IPMN had higher cumulative incidence of PDAC-RP (47.5%/10 yrs) than PDAC without IPMN (9.96%/10 yrs) (P = 0.0071). Moreover, the density of pancreatic intraepithelial neoplasia lesions in the background pancreas of cases of PDAC concomitant with IPMN (1.86/cm) was higher than that of cases of PDAC without IPMN (0.91/cm) (P = 0.0007). CONCLUSIONS: Concomitant IPMN in PDAC is an independent predictive factor for the development of new PDAC in remnant pancreas. Cancer susceptibility of remnant pancreas after resection for PDAC concomitant with IPMN is probably due to an increased density of pancreatic intraepithelial neoplasia lesions.

Ascending speed and nocturnal activity of adult masu salmon (Oncorhynchus masou Brevoort) during upstream migration.

We released five adult masu salmon (Oncorhynchus masou) tagged with external transmitters to track their ascending behaviour. The signals of all specimens were recorded in the upper area of the river system. Two patterns of ascending behaviour were recognized: ascending upward immediately after release and ascending during increased river discharge. The fastest ascending speed was about 1000 m h-1 . Active movements were detected at night. The signal recording duration at each receiver for each fish was generally brief. Most fish did not stay at the pools where the receivers were installed.

[Efficacy and safety of biosimilar filgrastim for autologous peripheral blood stem cell harvest and transplantation: a single-institutional retrospective analysis].

Three biosimilar filgrastim products are currently available in Japan. Among these, the safety and efficacy of two imported drugs for autologous peripheral blood stem cell harvest (autoPBSCH) and autologous peripheral blood stem cell transplantation (autoPBSCT) have been studied widely; however, evidence of the safety and efficacy of domestically manufactured filgrastim is limited. Therefore, we compared the efficacy and safety of domestic biosimilar filgrastim (BF1, n=23) with those of originator filgrastim (OF, n=21) for autoPBSCH and autoPBSCT. Before autoPBSCH, the same median total dose of 3.3 mg filgrastim was administered to patients in the BF1 and OF groups. Median numbers of CD34-positive cells harvested did not significantly differ between BF1 (4.32×106/kg) and OF (4.75×106/kg) groups. After autoPBSCT, the median total doses of BF1 and OF used for neutrophil recovery were 2.7 and 3.3 mg, respectively. There were no significant inter-group differences in the time to bone marrow recovery, total transfusion units, hospitalization duration, overall survival at 1 year, or adverse events. Compared with OF, the cost of BF1 was considerably lower by 229,529 yen per transplantation case. Thus, the efficacy and safety of BF1 were comparable to those of OF, making BF1 an effective and economical alternative to OF.

[Successful treatment with rituximab and romiplostim for thrombocytopenia associated with Waldenström's macroglobulinemia initially presenting as Evans syndrome].

A 60-year-old woman was admitted to our hospital with anemia and thrombocytopenia. Serum testing showed platelet-associated IgG elevation and she was positive on the direct and indirect Coombs tests. Together with bone marrow examination, these findings indicated a diagnosis of Evans syndrome. At diagnosis, she also had an IgM-κ type of monoclonal gammopathy of unknown significance. Initially, we administered steroids and her hemolytic anemia showed improvement. In contrast, only transient recovery of platelet counts was observed and her platelet counts rapidly decreased after steroid dose reduction. Thus, we treated her with a TPO-agonist, romiplostim. During the clinical course, she showed gradual serum IgM elevation. We thus performed another bone marrow biopsy and diagnosed her as having Waldenström's macroglobulinemia (WM). We started treatment with rituximab for WM. Together with the serum IgM reduction, she showed marked improvement of thrombocytopenia. This is a very rare case of WM initially presenting as autoimmune hemolytic anemia and immunethrombocytopenia associated with IgG class auto-antibody. Our experience suggests the usefulness of rituximab and romiplostim for the treatment of immunethrombocytopenia associated with WM.

[Adult T cell leukemia-lymphoma with allo-HSCT after treatment for pulmonary involvement with Mogamulizumab].

Adult T cell lymphoma-leukemia (ATL) is a highly aggressive disease and allogeneic hematopoietic transplantation (allo-HSCT) is the only therapeutic option for achieving a cure. However, some ATL patients cannot undergo HSCT. One of the important reasons for restricting HSCT in ATL is the high incidence of pulmonary complications associated with ATL including opportunistic infections, infiltration of ATL cells, and HTLV-1 associated bronchopneumonopathy. Herein, we report an ATL case with pulmonary infiltration of ATL cells successfully treated with allo-HSCT after improvement of pulmonary function with administration of the anti-CCR4 antibody mogamulizumab. To our knowledge, this is the first ATL case showing improvement of pulmonary invasion of ATL cells after treatment with mogamulizumab. In addition, this case suggests that mogamulizumab treatment might be useful as a bridge to allo-HSCT in ATL patients.

[Development of cytomegalovirus antigenemia in 3 patients with B cell lymphoma treated with bendamustine monotherapy].

Bendamustine is one of the new key drugs for patients with indolent lymphoma. Bendamustine, together with rituximab, significantly improves the treatment outcomes of these patients. In addition, previous clinical studies have shown the complication rate of severe infection in bendamustine-containing regimens to be relatively low as compared to those of conventional chemotherapeutic regimens such as CHOP. However, some clinical case reports have raised the possibility that bendamustine may abrogate the immune responses of patients and trigger opportunistic infections including cytomegalovirus reactivation. Herein, we report three indolent lymphoma cases becoming positive on cytomegalovirus antigenemia assay during bendamustine monotherapy. All events occurred after more than three courses of treatment with bendamustine. One patient showed decreased CD4 positive T lymphocytes before the development of cytomegalovirus antigenemia. All three patients were successfully treated with valganciclovir. Although the precise risk is unknown, it should be noted that bendamustine can potentially cause reactivation of/infection with cytomegalovirus and physicians should pay attention to the possibility of this infection during treatment with bendamustine-containing regimens.

Two cases of pancreatic neuroendocrine tumors with ectopic ACTH syndrome during their disease course.

Pancreatic neuroendocrine tumors (PanNETs) are rare malignant tumors that occur in the pancreas. They are divided into functioning and non-functioning tumors based on the presence or absence of their specific hormonal hyper-expression symptoms. Adrenocorticotropic hormone (ACTH)-producing PanNETs are rare, functional tumors, and their clinical characteristics and outcomes have not been well reported.Here, we report the cases of two patients with PanNETs who presented with ectopic ACTH syndrome (EAS) during the course of their disease. Case 1 involved a non-functioning PanNET at the time of surgery. During treatment for recurrent liver metastases, the patient presented with EAS and tumor-associated hypercalcemia, probably due to ACTH and parathyroid hormone-related peptide (PTHrP) production from the liver tumor. Case 2 was a gastrinoma, and similar to Case 1, this patient presented with EAS during the treatment of recurrent liver metastases.It is not uncommon for patients with PanNETs to have multiple hormones and develop secondary hormone secretion during their disease course, although tumor phenotypes differ between primary and metastatic sites. In patients with functioning PanNETs, symptom control with anti-hormonal therapy is essential, in addition to anti-tumor therapy, especially for EAS, which is an endocrine emergency disease that requires prompt diagnosis and treatment.

MicroRNA-20a in extracellular vesicles derived from duodenal fluid is a possible biomarker for pancreatic ductal adenocarcinoma.

Background: Pancreatic ductal adenocarcinoma (PDAC) has a high mortality rate owing to its late diagnosis and aggression. In addition, there are relatively few minimally invasive screening methods for the early detection of PDAC, making the identification of biomarkers for this disease a critical priority. Recent studies have reported that microRNAs in extracellular vesicles (EV-miRs) from bodily fluids can be useful for the diagnosis of PDACs. Given this, we designed this study to evaluate the utility of cancer EVs extracted from duodenal fluid (DF) and their resident EV-miRs as potential biomarkers for the detection of PDAC. Methods: EV-miRs were evaluated and identified in the supernatants of various pancreatic cancer cell lines (Panc-1, SUIT2, and MIAPaca2), human pancreatic duct epithelial cells, and the DF from patients with PDAC and healthy controls. EVs were extracted using ultracentrifugation and the relative expression of EV-miR-20a was quantified. Results: We collected a total of 34 DF samples (27 PDAC patients and seven controls) for evaluation and our data suggest that the relative expression levels of EV-miR-20a were significantly higher in patients with PDAC than in controls (p = 0.0025). In addition, EV-miR-20a expression could discriminate PDAC from control patients regardless of the location of the tumor with an area under the curve values of 0.88 and 0.88, respectively. Conclusions: We confirmed the presence of EVs in the DF and suggest that the expression of EV-miR-20a in these samples may act as a potential diagnostic biomarker for PDAC.

Patient-derived organoids of pancreatic ductal adenocarcinoma for subtype determination and clinical outcome prediction.

BACKGROUND: Recently, two molecular subtypes of pancreatic ductal adenocarcinoma (PDAC) have been proposed: the "Classical" and "Basal-like" subtypes, with the former showing better clinical outcomes than the latter. However, the "molecular" classification has not been applied in real-world clinical practice. This study aimed to establish patient-derived organoids (PDOs) for PDAC and evaluate their application in subtype classification and clinical outcome prediction. METHODS: We utilized tumor samples acquired through endoscopic ultrasound-guided fine-needle biopsy and established a PDO library for subsequent use in morphological assessments, RNA-seq analyses, and in vitro drug response assays. We also conducted a prospective clinical study to evaluate whether analysis using PDOs can predict treatment response and prognosis. RESULTS: PDOs of PDAC were established at a high efficiency (> 70%) with at least 100,000 live cells. Morphologically, PDOs were classified as gland-like structures (GL type) and densely proliferating inside (DP type) less than 2 weeks after tissue sampling. RNA-seq analysis revealed that the "morphological" subtype (GL vs. DP) corresponded to the "molecular" subtype ("Classical" vs. "Basal-like"). The "morphological" classification predicted the clinical treatment response and prognosis; the median overall survival of patients with GL type was significantly longer than that with DP type (P < 0.005). The GL type showed a better response to gemcitabine than the DP type in vitro, whereas the drug response of the DP type was improved by the combination of ERK inhibitor and chloroquine. CONCLUSIONS: PDAC PDOs help in subtype determination and clinical outcome prediction, thereby facilitating the bench-to-bedside precision medicine for PDAC.

Blockade of histamine receptor H1 augments immune checkpoint therapy by enhancing MHC-I expression in pancreatic cancer cells.

BACKGROUND: Although immune checkpoint blockade (ICB) therapy has proven to be extremely effective at managing certain cancers, its efficacy in treating pancreatic ductal adenocarcinoma (PDAC) has been limited. Therefore, enhancing the effect of ICB could improve the prognosis of PDAC. In this study, we focused on the histamine receptor H1 (HRH1) and investigated its impact on ICB therapy for PDAC. METHODS: We assessed HRH1 expression in pancreatic cancer cell (PCC) specimens from PDAC patients through public data analysis and immunohistochemical (IHC) staining. The impact of HRH1 in PCCs was evaluated using HRH1 antagonists and small hairpin RNA (shRNA). Techniques including Western blot, flow cytometry, quantitative reverse transcription polymerase chain reaction (RT-PCR), and microarray analyses were performed to identify the relationships between HRH1 and major histocompatibility complex class I (MHC-I) expression in cancer cells. We combined HRH1 antagonism or knockdown with anti-programmed death receptor 1 (αPD-1) therapy in orthotopic models, employing IHC, immunofluorescence, and hematoxylin and eosin staining for assessment. RESULTS: HRH1 expression in cancer cells was negatively correlated with HLA-ABC expression, CD8+ T cells, and cytotoxic CD8+ T cells. Our findings indicate that HRH1 blockade upregulates MHC-I expression in PCCs via cholesterol biosynthesis signaling. In the orthotopic model, the combined inhibition of HRH1 and αPD-1 blockade enhanced cytotoxic CD8+ T cell penetration and efficacy, overcoming resistance to ICB therapy. CONCLUSIONS: HRH1 plays an immunosuppressive role in cancer cells. Consequently, HRH1 intervention may be a promising method to amplify the responsiveness of PDAC to immunotherapy.

[Extramedullary onset of mixed phenotype acute leukemia with MLL gene rearrangement].

Rearrangements of the mixed lineage leukemia MLL gene at chromosome 11q23 are common chromosomal abnormalities in human leukemia. MLL fused with numerous partner genes causes different leukemia phenotypes that depend on the function of partner genes. MLLT3-MLL is generated by translocation t(9;11), which primarily induces acute myeloid leukemia in humans, whereas MLLT3-MLL induces ALL or biphenotypic leukemia in mice. The microenvironment that surrounds leukemia cells plays a central role in this process. We report a patient with mixed phenotype acute leukemia with MLLT3-MLL. This patient, a 44-year-old woman, initially exhibited extramedullary leukemia with multiple tumors and subsequently developed bone marrow disease. The leukemia cells exhibited myeloid (CD13 and MPO) and B cell (CD19 and CD79a) phenotypes. Chromosomal analysis and RT-PCR assay revealed tumor cells with the MLLT3-MLL fusion gene. We treated this patient with a drug regimen for AML (Ara-C plus anthracycline), and complete remission was obtained. This report describes the fourth case of mixed phenotypic leukemia with extramedullary disease. The extramedullary circumstance may underlie the biphenotypic features of these patients.

[Non-traumatic splenic rupture during the chemotherapy and successful management by emergency splenectomy in a patient with blastic plasmacytoid dendritic cell neoplasm].

Spontaneous rupture of the spleen is a rare but important complication in hematological malignancies. Without splenectomy, the mortality rate of these patients is nearly 100%. We present a blastic plasmacytoid dendritic cell neoplasm case with this complication. Nine days after initiation of chemotherapy, the patient had increased epigastric pain and a drop in hemoglobin. CT scan showed an enlarged spleen surrounded by hemorrhage. Spontaneous rupture of the spleen was diagnosed. Although the patient had severe bone marrow suppression due to chemotherapy, emergency splenectomy was performed and the patient recovered.

Eyestalk transcriptome and methyl farnesoate titers provide insight into the physiological changes in the male snow crab, Chionoecetes opilio, after its terminal molt.

The snow crab, Chionoecetes opilio, is a giant deep-sea brachyuran. While several decapod crustaceans generally continue to molt and grow throughout their lifetime, the snow crab has a fixed number of molts. Adolescent males continue to molt proportionately to their previous size until the terminal molt at which time an allometric increase in chela size occurs and an alteration of behavioral activities occurs, ensuring breeding success. In this study, we investigated the circulating concentrations of methyl farnesoate (an innate juvenile hormone in decapods) (MF) before or after the terminal molt in males. We then conducted eyestalk RNAseq to obtain molecular insight into the regulation of physiological changes after the terminal molt. Our analyses revealed an increase in MF titers after the terminal molt. This MF surge may be caused by suppression of the genes that encode MF-degrading enzymes and mandibular organ-inhibiting hormone that negatively regulates MF biosynthesis. Moreover, our data suggests that behavioral changes after the terminal molt may be driven by the activation of biogenic amine-related pathways. These results are important not only for elucidating the physiological functions of MFs in decapod crustaceans, which are still largely unknown, but also for understanding the reproductive biology of the snow crab.