P6493Syk activation is a defense mechanism in murine model of aortic dissection

Background

Aortic dissection (AD) is a serious clinical condition with unknown etiology that frequently results in fatal outcome. Recent studies showed essential role of inflammatory response both in promoting AD and aortic aneurysm (AA). However, the difference of the molecular pathogenesis between AD and AA is unclear. Previously, we reported that Syk, a tyrosine kinase that regulates differentiation and activation of inflammatory cells, promotes AA formation in a mouse model.

Objective

In the current study, we investigated the role of Syk in AD.

Methods and results

A mouse AD model was created by continuous infusion of beta-aminopropionitrile (125 mg/kg/day) and angiotensin II (1,000 ng/min/kg) (BAPN+AngII), which caused AD in approximately 80% of mice within 14 days. Immunohistochemical staining for activated (phosphorylated) Syk (pSyk) revealed that Syk was inactive in normal mouse aorta, but was activated in the aortic walls after AD development. Double immunofluorescence staining for pSyk and smooth muscle alpha actin showed that Syk was active not only in the infiltrating inflammatory cells, but also in smooth muscle cells in AD tissue. Western blot analysis revealed that BAPN+AngII treatment caused Syk activation at 3 days before AD development, followed by transient suppression, and reactivation at 14 days after AD development. We examined the significance of Syk activation in AD by treating mice with fostamatinib, a specific Syk inhibitor, before and during BAPN+AngII infusion. Notably, fostamatinib-treated group developed more severe AD compared to the vehicle-treated group. The AD lesion length was 3.80±0.86 mm for vehicle group and 8.87±1.69 mm for fostamatinib group (P<0.05, n=12 for each group). In addition, fostamatinib significantly worsened the mortality of mice due to the rupture of the aorta from 0% to 42% (P<0.05, n=12 for each group). Transcriptome analysis revealed that fostamatinib suppressed both positive and negative regulators of immune response, defense response and inflammatory response.

Conclusions

These findings uncovered the previously unrecognized role of Syk for protecting the aortic tissue in AD pathogenesis, and suggested fundamentally different disease mechanisms of AD and AA.

P4620Circulating concentration of presepsin improves early prediction of short-term mortality in patients treated at medical cardiac intensive care units

Background

Presepsin, a subtype of soluble CD14, is an inflammatory marker, which largely reflects monocytic activation. Presepsin appears to be an accurate diagnostic marker of sepsis, but its clinical significance remains unclear in cardiovascular disease.

Purpose

This prospective study aimed to investigate the predictive value of plasma presepsin levels on admission to medical (non-surgical) cardiac intensive care units (MCICUs) for short-term mortality.

Methods

We examined 1560 patients hospitalized in MCICUs and measured the baseline plasma presepsin levels at admission.

Results

Acute coronary syndrome was present in 46% of the patients, and acute decompensated heart failure in 36%. Before MCICUs admission, emergent coronary angiography or percutaneous coronary intervention was performed in 36%, mechanical ventilation was required for respiratory insufficiency in 2.1%, and intraaortic balloon pumps were needed for hemodynamic instability in 8.9%. During 6 months after admission, there were 113 (7.2%) deaths. Patients who died were older (median: 77 vs. 71 years, P<0.0001); had higher levels of presepsin (263 vs. 119 pg/mL, P<0.0001), B-type natriuretic peptide (BNP: 696 vs. 186 pg/mL, P<0.0001), high-sensitivity troponin T (hsTnT: 81 vs. 47 pg/mL, P=0.004), and high-sensitivity C-reactive protein (13.8 vs. 2.2 mg/L, P<0.0001); and had lower levels of estimated glomerular filtration rate (50 vs. 65 mL/min/1.73m2, P<0.0001) and left ventricular ejection fraction (43% vs. 51%, P<0.0001) than those of the survivors. In the multivariate Cox regression analysis, higher levels of presepsin (P=0.0002), BNP (P=0.04), and hsTnT (P=0.009) were all independent predictors of 6-month deaths. Quartiles of presepsin levels were associated with higher mortality rates within 6 months after admission (Table). Adding presepsin levels to a baseline model that included established risk factors, BNP, and hsTnT further enhanced reclassification (P=0.004) and discrimination (P=0.003) beyond that of the baseline model.

Mortality rates according to presepsin Presepsin quartile 1st 2nd 3rd 4th P value ≤80 pg/mL 81–124 pg/mL 125–232 pg/mL >232 pg/mL 1-month mortality 0.8% 2.0% 3.3% 8.0% <0.0001 6-month mortality 0.8% 3.8% 8.2% 16.3% <0.0001

Conclusions

Presepsin levels at admission could improve the prediction of short-term mortality in patients hospitalized at MCICUs.

Effect of tissue inhibitor of metalloprotease 1 on human pulp cells in vitro and rat pulp tissue in vivo

AIM

To evaluate the dentinogenetic effects of tissue inhibitor of metalloprotease (TIMP1) on human pulp cells in vitro and rat pulp tissue in vivo.

METHODOLOGY

The effect of TIMP1 on pulp cell functions related to hard tissue formation as part of the wound healing process (i.e. biocompatibility, proliferation, differentiation and mineralized nodule formation) was evaluated in vitro and using a direct pulp capping experimental animal model in vivo. The effects of different-sized cavity preparations on hard tissue formation induced by ProRoot MTA at 2 weeks were evaluated using micro-computed tomography (micro-CT). Tertiary dentine formation quality and quantity after pulp capping using TIMP1, ProRoot MTA and phosphate-buffered saline (PBS) was also evaluated after 4 weeks using micro-CT in term of dentine volume (DV), dentine mineral density (DVD) and histological analysis. The data were evaluated by Student's t-test, one-way ANOVA with Tukey's post hoc test, the Kruskal-Wallis test or the Steel-Dwass test. P values < 0.05 were considered statistically significant.

RESULTS

TIMP1 significantly stimulated dental pulp stem cell proliferation, differentiation, and mineralization and was more biocompatible compared with the PBS control (P < 0.05). In the pulp capping model, the amount of tertiary dentine that formed was directly proportional to the size of the pulp exposure; greater amounts of tertiary dentine were observed in pulps with larger exposures after 2 weeks. 4-week samples of TIMP1 and ProRoot MTA had similar characteristics, but both sample significantly induced tertiary dentine formation beneath the cavity compared with PBS (P <  0.05) under standardized cavity preparations.

CONCLUSIONS

TIMP1 has an important role in pulpal wound healing, which makes it a potential biological pulp capping material and candidate molecule for regenerative endodontic therapy.

Abstract P1-11-07: Risk analysis for chemotherapy induced nausea and vomiting (CINV) in patients receiving FEC100 treatment

BACKGROUND:

Anthracycline-containing regimens are standard treatment options in adjuvant and neoadjuvant chemotherapy in breast cancer. Chemotherapy-induced nausea and vomiting (CINV) is experienced frequently in patients receiving these regimens, but the risk factors for CINV are unknown.

OBJECTIVE:

The aim of this study was to investigate risk factors for CINV in anthracycline-containing regimens retrospectively.

METHODS:

Data were collected from the JONIE study, which was conducted in order to estimate the efficacy of zoledronic acid in a neoadjuvant setting from March 2010 to June 2012 (UMIN000003261). A total of 180 patients were recruited, and we used CINV data from the first cycle of FEC100 treatment and patient backgrounds. As the protocol regulation allowed the use of antiemetic drugs,in the first cycle of the FEC100 regimen, patients received various types of antiemetic agents, which we classified into four groups: Dexamethasone (DEX)+5-HT3 receptor antagonist (5-HT3)+neurokinin-1 receptor antagonist (NK1) (DEX+5-HT3+NK1) group; Dexamethasone (DEX)+5-HT3 receptor antagonist (5-HT3) (DEX+5HT3) group; Dexamethasone (DEX)+5-HT3 receptor antagonist (5-HT3)+dopamine receptor antagonist (DRA) (DEX+5HT3+DRA) group; and Dexamethasone (DEX)+5-HT3 receptor antagonist (5-HT3)+neurokinin-1 receptor antagonist (NK1)+ dopamine receptor antagonist (DRA) (DEX+5-HT3+NK1+DRA) group. Risk factors were selected from patient backgrounds and the combinations of antiemetic drugs. In patient backgrounds, the body mass index (BMI) was stratified into 3 categories: Less than 18.5 (underweight group); equal to or more than 18.5 but less than 25 (standard BMI group); and equal to or more than 25 (overweight group). The risks for CINV were analyzed by univariate and multivariate analyses. P values of less than 0.05 were defined as significant.

RESULTS:

In a univariate analysis of nausea, the body mass index (BMI) was the only significant factor (P&lt;0.05). On the other hand, BMI and the combination of antiemetic drugs were significant factors in vomiting. (P&lt;0.05 and 0.005, respectively). In a multivariate analysis of nausea, the P value for BMI was 0.02. The odds ratio for the underweight group was 7.745 (confidence interval: 2.171 to 27.634) compared with the standard BMI group. In a multivariate analysis of vomiting, BMI and the combination of antiemetic drugs were significant risk factors (P=0.025 and 0.023, respectively). The odds ratio for the underweight group was 3.481 (confidence interval: 1.183 to 10.241)compared with the standard BMI group. Furthermore, the odds ratios in the DEX+5-HT3+DRA and DEX+5HT3 groups were 5.005 (confidence interval: 1.543 to 16.239) and 4.178 (confidence interval: 1.428 to 12.222), respectively, compared with the DEX+5-HT3+NK1 group, which was consistent with the CINV guidelines in 2011.

CONCLUSIONS:

This study revealed that BMI was the most important risk factor for nausea, and that BMI and the combination of antiemetic drugs were risk factors for vomiting. Underweight-patients tend to have CINV in anthracycline-containing regimen. The DEX+5-HT3+NK1 group was the best antiemetic drug combination. These result show that following the CINV guideline treatment is mandatory in order to prevent CINV.

Citation Format: Hayashi M, Nakazawa K, Hasegawa Y, Horiguchi J, Miura D, Ishikawa T, Takao S, Kim SJ, Yamagami K, Miyashita M, Konishi M, Shigeoka Y, Suzuki M, Taguchi T, Kubota T, Tanino Y, Yamada K, Kimura K, Akazawa K, Kohno N. Risk analysis for chemotherapy induced nausea and vomiting (CINV) in patients receiving FEC100 treatment [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P1-11-07.

Abstract OT3-02-02: PATHWAY: Asian, multicenter, phase 3 trial of tamoxifen with or without palbociclib ± goserelin in women with hormone receptor-positive, HER2-negative advanced or metastatic breast cancer

BACKGROUND:

The incidence rates of breast cancer (BC) in Asian counties have been rising rapidly. The age-specific female BC incidence rates peak before menopause (around 40-50 years of age) in Asia, however treatment options for pre/perimenopausal patients are limited. Palbociclib (P) is an oral novel cyclin-dependent kinase 4/6 (CDK4/6) inhibitor. The addition of P to endocrine therapy (ET) such as aromatase inhibitor or fulvestrant has been demonstrated improved progression-free survival (PFS) in phase 3 studies PALOMA-2 and PALOMA-3. This study is designed to evaluate efficacy and safety of P plus tamoxifen (TAM) in patients with hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative advanced or metastatic BC regardless of menopausal status. This study is conducted as a Clinical Research Collaboration by National Cancer Center Hospital with research funding from Pfizer.

TRIAL DESIGN:

PATHWAY/NCCH1607 is a double-blind, placebo-controlled, randomized, phase 3 study. Patients will be randomized 1:1 to receive either P (125 mg once daily, days1-21 of a 28-day cycle) or placebo in combination with TAM (20 mg once daily, continuously). Pre/perimenopausal women should receive concurrent ovarian function suppression with goserelin. Randomization will be stratified by prior ET for advanced/metastatic BC (1st line ET vs. 2nd line ET) and menopausal status (pre/perimenopausal vs. postmenopausal).

KEY ELIGIBILITY CRITERIA:

Eligible patients include women of any menopausal status with HR-positive, HER2-negative advanced or metastatic BC; candidates to receive TAM as 1st line or 2nd line ET for advanced/metastatic disease; ≥18 years of age; measurable or non-measurable disease (RECIST v.1.1); ECOG performance status 0-1; adequate organ function; have not received treatment with TAM (except for patients who have had more than 12 months from completion of adjuvant therapy with TAM); and have not received any CDK4/6 or phosphoinositide 3-kinase (PI3K) - mammalian target of rapamycin (mTOR) inhibitors.

SPECIFIC AIMS:

The primary endpoint is PFS as assessed by the investigator. Secondary endpoints include overall survival (OS), 1, 2, and 3-year survival probabilities, objective response (OR), duration of response, clinical benefit rate (CBR), pharmacokinetics, safety, and patient-reported outcomes.

STATISTICAL METHODS:

The sample size was determined to detect a 38% reduction in the hazard of disease progression or death in P plus TAM arm with a 1-sided significance level of 2.5% and power of 80%. A stratified log rank test will be used to compare PFS between the 2 treatment arms.

PRESENT ACCRUAL AND TARGET ACCRUAL:

Target accrual of 180 patients will be enrolled within 23 sites among Japan, Korea, Taiwan, and Singapore. As of June 2018, 46 patients have been enrolled.

CONTACT INFORMATION:

This trial is registered at ClinicalTrials.gov NCT03423199 and UMIN000030816. For more information, email NCCH1607_office@ml.res.ncc.go.jp

Citation Format: Noguchi E, Hata T, Nakamura K, Kuchiba A, Hayashi M, Hamada A, Yonemori K, Sohn J, Lu Y-S, Yap Y-S, Fujiwara Y, Tamura K. PATHWAY: Asian, multicenter, phase 3 trial of tamoxifen with or without palbociclib ± goserelin in women with hormone receptor-positive, HER2-negative advanced or metastatic breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr OT3-02-02.

Abstract OT1-05-04: Phase 3 trial of carboplatin in triple negative breast cancer (TNBC) patients with residual invasive carcinoma after neoadjuvant chemotherapy (JONIE4:J-CAT trial)

Background: It is well known that the prognosis of non pCR TNBC patients was poor after anthracycline and taxan treatment. For such patients, capecitabine seems to be effective to reduce recurrence based on the HR 0.58 of the CREATE X trial (Masuda, N. et al. Adjuvant Capecitabine for Breast Cancer after Preoperative Chemotherapy. N Engl J Med. 376, 2147. 2017) . However, the target of capecitabine is still unclear for TNBC. We classified non pCR tumors as BRCAness and Sporadic using BRCAness test(MRC-Holland, Amsterdam, the Netherlands). The recurrence rate of the BRCAness group was about 70%. Carboplatine is expected to be effective against BRCAness tumors, as it is a DNA damaging agent. In this study BRCAness can be checked just before carboplatin treatment using surgical specimens. Then the efficacy of carboplatin will be directly known to make comparison between DFS in the carboplatin group and that of the observation group.

Trial design: This is anopen label, randomized phase III study that will enroll TNBC with residual invasive cancer after surgery with preoperative chemotherapy including both anthracycrine and taxan. Patients are randomly assigned to either the carboplatin group or observation group. The patients in the carboplatin group are treated with carboplatin at AUC 6 and those in the observation group are observed at only 3 years.

Eligibility criteria:

1) ER and PgR&lt;1%, HER2 0, 1+ or 2+ with FISH negative on core needle biopsy before the chemotherapy and surgical specimens.

2) Preoperative chemotherapy including both anthracycrine and taxan.

3) Residual invasive cancer on breast tumors or lymph node metastasis in surgical specimens.

4) 20-79 year old women.

5) No chemotherapy within 5 years.

6) Not bilateral breast cancer, without metastasis, no prior breast cancer.

7) No severe bone marrow suppression.

Specific aims:Primary objective is DFS (Disease Free Survival). Secondary objectives are overall survival and safety.

STATISTICAL METHODS:

The 3 years recurrence rate of the observation group was estimated as 40% and hazard ratio at 0.58 based on the CREATE X trial. For both groups, 135 patients are necessary. This study is powered to approximately 80% to test the superiority of carboplatin group at a 2-sided α=0.05 using a stratified log-rank test.

Activation Date:22ndMarch 2018. No patients had been enrolled till 3rd July.

Citation Format: Tanino H, Suzuki M, Kaise H, Miyashita M, Chishima T, Hayashi M, Miyoshi Y, Futamura M, Ohtani S, Nagahashi M, Ohta T, Kosaka Y, Ishikawa T, Hasegawa Y, Kubota T, Sangai T, Iwatani T, Yamada A, Akazawa K, Kohno N. Phase 3 trial of carboplatin in triple negative breast cancer (TNBC) patients with residual invasive carcinoma after neoadjuvant chemotherapy (JONIE4:J-CAT trial) [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr OT1-05-04.

Synaptotagmin XIII expression and peritoneal metastasis in gastric cancer

BACKGROUND

Peritoneal metastasis is a frequent cause of death in patients with gastric cancer. The aim of this study was to identify molecules responsible for mediating peritoneal metastasis of gastric cancer.

METHODS

Transcriptome and bioinformatics analyses were conducted to identify molecules associated with peritoneal metastasis. The therapeutic effects of intraperitoneally administered small interfering (si) RNA were evaluated using mouse xenograft models. Expression of mRNA and protein was determined in gastric tissues from patients with gastric cancer.

RESULTS

Synaptotagmin XIII (SYT13) was expressed at significantly higher levels in patients with peritoneal recurrence, but not in those with hepatic or distant lymph node recurrence. Inhibition of SYT13 expression in a gastric cancer cell line transfected with SYT13-specific siRNA (siSYT13) was associated with decreased invasion and migration ability of the cells, but not with proliferation and apoptosis. Intraperitoneal administration of siSYT13 significantly inhibited the growth of peritoneal nodules and prolonged survival in mice. In an analysis of 200 patients with gastric cancer, SYT13 expression in primary gastric cancer tissues was significantly greater in patients with peritoneal recurrence or metastasis. A high level of SYT13 expression in primary gastric cancer tissues was an independent risk factor for peritoneal recurrence.

CONCLUSION

SYT13 expression in gastric cancer is associated with perioneal metatases and is a potential target for treatment.

Pulp Regeneration by 3-dimensional Dental Pulp Stem Cell Constructs

Dental pulp regeneration therapy for the pulpless tooth has attracted recent attention, and clinical trial studies are underway with the tissue engineering approach. However, there remain many concerns, including the extended period for regenerating the dental pulp. In addition, the use of scaffolds increases the risk of inflammation and infection. To establish a basic technology for novel dental pulp regenerative therapy that allows transplant of pulp-like tissue, we attempted to fabricate scaffold-free 3-dimensional (3D) cell constructs composed of dental pulp stem cells (DPSCs). Furthermore, we assessed viability of these 3D DPSC constructs for dental pulp regeneration through in vitro and in vivo studies. For the in vitro study, we obtained 3D DPSC constructs by shaping sheet-like aggregates of DPSCs with a thermoresponsive hydrogel. DPSCs within constructs remained viable even after prolonged culture; furthermore, 3D DPSC constructs possessed a self-organization ability necessary to serve as a transplant tissue. For the in vivo study, we filled the human tooth root canal with DPSC constructs and implanted it subcutaneously into immunodeficient mice. We found that pulp-like tissues with rich blood vessels were formed within the human root canal 6 wk after implantation. Histologic analyses revealed that transplanted DPSCs differentiated into odontoblast-like mineralizing cells at sites in contact with dentin; furthermore, human CD31-positive endothelial cells were found at the center of regenerated tissue. Thus, the self-organizing ability of 3D DPSC constructs was active within the pulpless root canal in vivo. In addition, blood vessel-rich pulp-like tissues can be formed with DPSCs without requiring scaffolds or growth factors. The technology established in this study allows us to prepare DPSC constructs with variable sizes and shapes; therefore, transplantation of DPSC constructs shows promise for regeneration of pulpal tissue in the pulpless tooth.

Abstract P6-15-05: Randomized controlled trial of neoadjuvant eribulin mesylate versus paclitaxel in women with operable breast cancer (JONIE-3 study)

Background:

Although treatment of eribulin mesylate (E) improved overall survival in metastatic breast cancer (BC) patients, little is known about the efficacy in early BC. The hypothesis of this study is that sequential administration of E followed by FEC would have less toxic, particularly peripheral neuropathy, and also have similar effect compared to paclitaxel (P) followed by FEC as primary systemic therapy (PST) for woman with operable BC.

Methods:

This is a phase II multicenter open label study (UMIN000012817). Patients (pts) were randomly assigned to either E (1.4mg/m2, d1 and d8, q21 days, 4 cycles) + FEC (fluorouracil 500 mg/m2, epirubicin 100 mg/m2, and cyclophosphamide 500 mg/m2) or P (80mg/m2, weekly, 12 cycles) + FEC as PST. HER2+ patients were allowed to receive trastuzumab. Stratification factors were ER, HER2, and menopausal status. Primary endpoint was the incidence of peripheral sensory and motor neuropathy (PSN and PMN) with Grade 1 or higher according to CTCAE ver.4.0. Secondary endpoints were pathological complete response (pCR) rates (ypT0/is/ypN0), clinical response rates (CR+PR), and adverse events. Safety was assessed in all pts who received at least one dose of the study drug.

Results:

Between 12/2013 to 3/2016, 121 pts were randomly assigned equally to E + FEC and P + FEC. Excluding 5 pts from the primary assessment, 116 pts (58 in each group) were included in the full analysis set. The characteristics of the pts were similar in the two arms. At the end of E or P administration, the incidences of PSN were 55.4% and 92.9% in E and P arm, respectively (p&lt;0.001). The incidences of PMN were 25.9% and 44.9% in E and P arm, respectively (p=0.049). At the end of E or P + FEC, PSN accounts for 38.9% in E arm and 85.2% in P arm (p&lt;0.001), and PMN accounts for 20.7% in E arm and 32.8% in P arm (p=0.201). The pCR rates in E and P arm were 20.7% and 29.8% (p=0.092). The clinical response rates in E and P arm were 82.2% and 91.0% (p=0.108). No statistical significant difference was found in efficacy of PST between E and P.

Conclusion:

This randomized phase II study revealed that eribulin had favorable peripheral neuropathy profile with modest efficacy in the neoadjuvant setting, compared with paclitaxel.

Citation Format: Miura D, Hasegawa Y, Ishikawa T, Tachibana A, Horiguchi J, Hayashi M, Miyashita M, Kubota T, Narui K, Suzuki M, Akazawa K, Kohno N. Randomized controlled trial of neoadjuvant eribulin mesylate versus paclitaxel in women with operable breast cancer (JONIE-3 study) [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P6-15-05.

Electrophysiological properties of anion exchangers in the luminal membrane of guinea pig pancreatic duct cells

The pancreatic duct epithelium secretes the HCO₃⁻-rich pancreatic juice. The HCO₃⁻ transport across the luminal membrane has been proposed to be mediated by SLC26A Cl⁻–HCO₃⁻ exchangers. To examine the electrophysiological properties of Cl⁻–HCO₃⁻ exchangers, we directly measured HCO₃⁻ conductance in the luminal membrane of the interlobular pancreatic duct cells from guinea pigs using an inside-out patch-clamp technique. Intracellular HCO₃⁻ increased the HCO₃⁻ conductance with a half-maximal effective concentration value of approximately 30 mM. The selectivity sequence based on permeability ratios was SCN⁻ (1.4) > Cl⁻ (1.2) = gluconate (1.1) = I⁻ (1.1) = HCO₃⁻ (1.0) > methanesulfonate (0.6). The sequence of the relative conductance was HCO₃⁻ (1.0) > SCN⁻ (0.7) = I⁻ (0.7) > Cl⁻ (0.5) = gluconate (0.4) > methanesulfonate (0.2). The current dependent on intracellular HCO₃⁻ was reduced by replacement of extracellular Cl⁻ with gluconate or by H₂DIDS, an inhibitor of Cl⁻–HCO₃⁻ exchangers. RT-PCR analysis revealed that the interlobular and main ducts expressed all SLC26A family members except Slc26a5 and Slc26a8. SLC26A1, SLC26A4, SLC26A6, and SLC26A10 were found to be localized to the luminal membrane of the guinea pig pancreatic duct by immunohistochemistry. These results demonstrate that these SLC26A Cl⁻–HCO₃⁻ exchangers may mediate the electrogenic HCO₃⁻ transport through the luminal membrane and may be involved in pancreatic secretion in guinea pig ducts.