Emapalumab as salvage therapy for adults with malignancy-associated hemophagocytic lymphohistiocytosis.

Not available.

The CNS Relapse in T-Cell Lymphoma Index Predicts CNS Relapse in Patients with T- and NK-Cell Lymphomas.

Little is known about risk factors for central nervous system (CNS) relapse in mature T- and NK-cell neoplasms (MTNKN). We aimed to describe the clinical epidemiology of CNS relapse in patients with MTNKN and developed the CNS relapse In T-cell lymphoma Index (CITI) to predict patients at highest risk of CNS relapse. We reviewed data from 135 patients with MTNKN and CNS relapse from 19 North American institutions. After exclusion of leukemic and most cutaneous forms of MTNKN, patients were pooled with non-CNS relapse control patients from a single institution to create a CNS relapse-enriched training set. Using a complete case analysis (N=182), of whom 91 had CNS relapse, we applied a LASSO Cox regression model to select weighted clinicopathologic variables for the CITI score, which we validated in an external cohort from the Swedish Lymphoma Registry (N=566). CNS relapse was most frequently observed in patients with PTCL, NOS (25%). Median time to CNS relapse and median overall survival after CNS relapse was 8.0 months and 4.7 months, respectively. We calculated unique CITI risk scores for individual training set patients and stratified them into risk terciles. Validation set patients with low-risk (N=158) and high-risk (N=188) CITI scores had a 10-year cumulative risk of CNS relapse of 2.2% and 13.4%, respectively (HR 5.24, 95%CI 1.50-18.26, P=0.018). We developed an open-access web-based CITI calculator (https://redcap.link/citicalc) to provide an easy tool for clinical practice. The CITI score is a validated model to predict patients with MTNKN at highest risk of developing CNS relapse.

TP63 fusions drive multicomplex enhancer rewiring, lymphomagenesis, and EZH2 dependence.

Gene fusions involving tumor protein p63 gene (TP63) occur in multiple T and B cell lymphomas and portend a dismal prognosis for patients. The function and mechanisms of TP63 fusions remain unclear, and there is no target therapy for patients with lymphoma harboring TP63 fusions. Here, we show that TP63 fusions act as bona fide oncogenes and are essential for fusion-positive lymphomas. Transgenic mice expressing TBL1XR1::TP63, the most common TP63 fusion, develop diverse lymphomas that recapitulate multiple human T and B cell lymphomas. Here, we identify that TP63 fusions coordinate the recruitment of two epigenetic modifying complexes, the nuclear receptor corepressor (NCoR)-histone deacetylase 3 (HDAC3) by the N-terminal TP63 fusion partner and the lysine methyltransferase 2D (KMT2D) by the C-terminal TP63 component, which are both required for fusion-dependent survival. TBL1XR1::TP63 localization at enhancers drives a unique cell state that involves up-regulation of MYC and the polycomb repressor complex 2 (PRC2) components EED and EZH2. Inhibiting EZH2 with the therapeutic agent valemetostat is highly effective at treating transgenic lymphoma murine models, xenografts, and patient-derived xenografts harboring TP63 fusions. One patient with TP63-rearranged lymphoma showed a rapid response to valemetostat treatment. In summary, TP63 fusions link partner components that, together, coordinate multiple epigenetic complexes, resulting in therapeutic vulnerability to EZH2 inhibition.

TP53 mutations identify high-risk events for peripheral T-cell lymphoma treated with CHOP-based chemotherapy.

Nodal peripheral T-cell lymphomas (PTCL), the most common PTCLs, are generally treated with cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP)-based curative-intent chemotherapy. Recent molecular data have assisted in prognosticating these PTCLs, but most reports lack detailed baseline clinical characteristics and treatment courses. We retrospectively evaluated cases of PTCL treated with CHOP-based chemotherapy that had tumors sequenced by the Memorial Sloan Kettering Integrated Mutational Profiling of Actionable Cancer Targets next-generation sequencing panel to identify variables correlating with inferior survival. We identified 132 patients who met these criteria. Clinical factors correlating with an increased risk of progression (by multivariate analysis) included advanced-stage disease and bone marrow involvement. The only somatic genetic aberrancies correlating with inferior progression-free survival (PFS) were TP53 mutations and TP53/17p deletions. PFS remained inferior when stratifying by TP53 mutation status, with a median PFS of 4.5 months for PTCL with a TP53 mutation (n = 21) vs 10.5 months for PTCL without a TP53 mutation (n = 111). No TP53 aberrancy correlated with inferior overall survival (OS). Although rare (n = 9), CDKN2A-deleted PTCL correlated with inferior OS, with a median of 17.6 months vs 56.7 months for patients without CDKN2A deletions. This retrospective study suggests that patients with PTCL with TP53 mutations experience inferior PFS when treated with curative-intent chemotherapy, warranting prospective confirmation.

Arsenic-contaminated drinking water and cholangiocarcinoma.

INTRODUCTION: Cholangiocarcinoma (CCA) is an aggressive tumor occurring in bile ducts and associated with dismal outcomes. It can be classified according to anatomical location as intrahepatic cholangiocarcinoma (ICC) or extrahepatic cholangiocarcinoma (ECC). Although some risk factors have been identified, our understanding of these tumors remains limited. Arsenic (As) is a prevalent toxicant with established associations with bladder, skin and lung cancers while pilot data on its potential carcinogenic role on digestive tumors are emerging. This ecological study aimed to investigate the association between exposure to As-contaminated drinking water and CCA. METHODS: Analyses were conducted for the US, Taiwan and India due to the quality of publicly available datasets including small area-level information. Statistics included coefficient correlations analyses as well as univariate and multivariate linear regressions. RESULTS: In the US, no correlation was observed between As and CCA. In Taiwan, correlations were identified for ICC in men (Spearman = 0.55, P = 0.01) and women (Spearman = 0.67, P < 0.01), as well as for ECC in men (Spearman = 0.62, P < 0.01). In India, counties with As level of at least 50 µg/L showed higher incidences of ECC in men ( R2 = 0.26, P = 0.01) and women ( R2 = 0.31, P < 0.01). CONCLUSION: These findings highlighted a potential carcinogenic impact of As in drinking water on bile duct cancers, paving the way for future studies aiming to replicate this association with individual data as well as its clinical and ecological implications.

A phase 2 biomarker-driven study of ruxolitinib demonstrates effectiveness of JAK/STAT targeting in T-cell lymphomas.

Signaling through JAK1 and/or JAK2 is common among tumor and nontumor cells within peripheral T-cell lymphoma (PTCL). No oral therapies are approved for PTCL, and better treatments for relapsed/refractory disease are urgently needed. We conducted a phase 2 study of the JAK1/2 inhibitor ruxolitinib for patients with relapsed/refractory PTCL (n = 45) or mycosis fungoides (MF) (n = 7). Patients enrolled onto 1 of 3 biomarker-defined cohorts: (1) activating JAK and/or STAT mutations, (2) ≥30% pSTAT3 expression among tumor cells by immunohistochemistry, or (3) neither or insufficient tissue to assess. Patients received ruxolitinib 20 mg PO twice daily until progression and were assessed for response after cycles 2 and 5 and every 3 cycles thereafter. The primary endpoint was clinical benefit rate (CBR), defined as the combination of complete response, partial response (PR), and stable disease lasting at least 6 months. Only 1 of 7 patients with MF had CBR (ongoing PR > 18 months). CBR among the PTCL cases (n = 45) in cohorts 1, 2, and 3 were 53%, 45%, and 13% (cohorts 1 & 2 vs 3, P = .02), respectively. Eight patients had CBR > 12 months (5 ongoing), including 4 of 5 patients with T-cell large granular lymphocytic leukemia. In an exploratory analysis using multiplex immunofluorescence, expression of phosphorylated S6, a marker of PI3 kinase or mitogen-activated protein kinase activation, in <25% of tumor cells was associated with response to ruxolitinib (P = .05). Our findings indicate that ruxolitinib is active across various PTCL subtypes and support a precision therapy approach to JAK/STAT inhibition in patients with PTCL. This trial was registered at www.clincialtrials.gov as #NCT02974647.

Romidepsin and lenalidomide-based regimens have efficacy in relapsed/refractory lymphoma: Combined analysis of two phase I studies with expansion cohorts.

Romidepsin (histone deacetylase inhibitor), lenalidomide (immunomodulatory agent), and carfilzomib (proteasome inhibitor), have efficacy and lack cumulative toxicity in relapsed/refractory lymphoma. We performed two investigator initiated sequential phase I studies to evaluate the maximum tolerated dose (MTD) of romidepsin and lenalidomide (regimen A) and romidepsin, lenalidomide, and carfilzomib (regimen B) in relapsed/refractory lymphoma. Cohorts in T-cell lymphoma (TCL), B-cell lymphoma (BCL) were enrolled at the MTD. Forty-nine patients were treated in study A (27 TCL, 17 BCL, 5 Hodgkin lymphoma (HL)) and 27 (16 TCL, 11 BCL) in study B. The MTD of regimen A was romidepsin 14 mg/m2 IV on days 1, 8, and 15 and lenalidomide 25 mg oral on days 1-21 of a 28-day cycle. The MTD of regimen B was romidepsin 8 mg/m2 on days 1 and 8, lenalidomide 10 mg oral on days 1-14 and carfilzomib 36 mg/m2 IV on days 1 and 8 of a 21-day cycle. In study A, 94% had AEs ≥Grade 3, most commonly neutropenia (49%), thrombocytopenia (53%), and electrolyte abnormalities (49%). In study B 59% had AEs ≥Grade 3, including thrombocytopenia (30%) and neutropenia (26%). In study A the ORR was 49% (50% TCL, 47% BCL, 50% HL). In study B the ORR was 48% (50% TCL, 50% BCL). For study A and B the median progression free survival (PFS) was 5.7 months and 3.4 months respectively with 11 patients proceeding to allogeneic transplant. The combinations of romidepsin and lenalidomide and of romidepsin, lenalidomide and carfilzomib showed activity in relapsed/refractory lymphoma with an acceptable safety profile.

Phase II Trial of Pembrolizumab Plus Gemcitabine, Vinorelbine, and Liposomal Doxorubicin as Second-Line Therapy for Relapsed or Refractory Classical Hodgkin Lymphoma.

PURPOSE: We conducted a phase II study evaluating pembrolizumab plus gemcitabine, vinorelbine, and liposomal doxorubicin (pembro-GVD) as second-line therapy for relapsed or refractory (rel/ref) classical Hodgkin lymphoma (cHL) (ClinicalTrials.gov identifier: NCT03618550). METHODS: Transplant eligible patients with rel/ref cHL following first-line therapy were treated with two to four cycles of pembrolizumab (200 mg intravenous [IV], day 1), gemcitabine (1,000 mg/m2 IV, days 1 and 8), vinorelbine (20 mg/m2 IV, days 1 and 8), and liposomal doxorubicin (15 mg/m2, days 1 and 8), given on 21-day cycles. The primary end point was complete response (CR) following up to four cycles of pembro-GVD. Patients who achieved CR by labeled fluorodeoxyglucose-positron emission tomography (Deauville ≤ 3) after two or four cycles proceeded to high-dose therapy and autologous hematopoietic cell transplantation (HDT/AHCT). HDT/AHCT was carried out according to institutional standards, and brentuximab vedotin maintenance was allowed following HDT/AHCT. RESULTS: Of 39 patients enrolled, 41% had primary ref disease and 38% relapsed within 1 year of frontline treatment. 31 patients received two cycles of pembro-GVD, and eight received four cycles. Most adverse events were grade 1 or two, whereas few were grade 3 and included transaminitis (n = 4), neutropenia (n = 4), mucositis (n = 2), thyroiditis (n = 1), and rash (n = 1). Of 38 evaluable patients, overall and CR rates after pembro-GVD were 100% and 95%, respectively. Thirty-six (95%) patients proceeded to HDT/AHCT, two received pre-HDT/AHCT involved site radiation, and 13 (33%) received post-HDT/AHCT brentuximab vedotin maintenance. All 36 transplanted patients are in remission at a median post-transplant follow-up of 13.5 months (range: 2.66-27.06 months). CONCLUSION: Second-line therapy with pembro-GVD is a highly effective and well-tolerated regimen that can efficiently bridge patients with rel/ref cHL to HDT/AHCT.

Outcomes of adult T-Cell leukemia/lymphoma with allogeneic stem cell transplantation: single-institution experience.

Few publications exist concerning allogeneic hematopoietic cell transplant (alloHCT) outcomes in non-Japanese patients with HTLV-1-associated ATLL. We detail the patient and disease characteristics, transplant approach, and clinical outcomes in 17 patients with ATLL at our institution who underwent alloHCT. We report favorable outcomes, with 8/17 in ongoing remission, 2/17 with prolonged (>6 years) disease-free survival, and a low incidence of transplant-related mortality (2/17). These results validate the feasibility and efficacy of alloHCT in non-Japanese patients with ATLL.

T follicular helper phenotype predicts response to histone deacetylase inhibitors in relapsed/refractory peripheral T-cell lymphoma.

Histone deacetylase inhibitors (HDACi) are active agents for peripheral T-cell lymphoma (PTCL). Anecdotally angioimmunoblastic T-cell lymphoma (AITL) appears to respond better than PTCL-not otherwise specified (NOS) to HDACi. The new World Health Organization classification shows that a subgroup of PTCL carries similarities in phenotype and gene expression profiling to AITL, comparable to T follicular helper (TFH) cells. The disease might behave similarly to AITL when treated with HDACi. We analyzed 127 patients with AITL or PTCL-NOS treated with HDACi at relapse as a single agent or in combination. We re-reviewed the pathology of all PTCL-NOS to identify the TFH phenotype. Patients received HDACi at relapse as a single agent in 97 cases (76%, 59 TFH, 38 non-TFH) or in combination in 30 cases (24%, 18 TFH, 12 non-TFH) including duvelisib, lenalidomide, lenalidomide plus carfilzomib, and pralatrexate. Seven PTCL-NOS had TFH phenotype; 2 PTCL-NOS were reclassified as AITL. Overall response rate (ORR) was 56.5% (28.9% complete response [CR]) in TFH and 29.4% (19.6% CR) in non-TFH phenotype patients (P = .0035), with TFH phenotype being an independent predictor of ORR (P = .009). Sixteen patients sufficiently responded to HDACi or HDACi in combination with another agent to proceed directly to allogeneic transplantation; 1 of 16 responded to donor lymphocyte infusion (12 TFH, 4 non-TFH). Our results, although retrospective, support that HDACi, as a single agent or in combination, may have superior activity in TFH-PTCL compared with non-TFH PTCL. This differential efficacy could help inform subtype-specific therapy and guide interpretation of HDACi trials.

Risk of breast implant associated anaplastic large cell lymphoma (BIA-ALCL) in a cohort of 3546 women prospectively followed long term after reconstruction with textured breast implants.

BACKGROUND: The risk of BIA-ALCL for patients with textured breast implants has been estimated between 1/2832 and 1/30,000 women. Existing studies estimating the numbers exposed and at risk, may have under reported cases, and/or lacked comprehensive follow-up. Our objective is to determine the risk of BIA-ALCL in a defined cohort of patients reconstructed with macro-textured breast implants and consistently followed long-term. METHODS: A prospective cohort study was conducted in patients who underwent breast reconstruction by a single surgeon at Memorial Sloan Kettering Cancer Center (MSKCC) from December 1992 to December 2017. Major events related to implants were prospectively recorded. We identified cases of BIA-ALCL by cross-checking clinical, pathology and external records data. Patients were followed until lymphoma occurrence or last follow-up. The primary outcomes were incidence rate per person-years and cumulative incidence. RESULTS: From 1992 to 2017, 3546 patients underwent 6023 breast reconstructions, mainly after breast cancer removal, or contralateral prophylactic mastectomy, using macro-textured surface expanders and implants. All reconstructions were performed by a single surgeon (PGC). Median follow-up was 8.1 years (range, 3 months - 30.9 years). Ten women, 1/354, developed ALCL after a median exposure of 11.5 years (range, 7.4-15.8 years). Overall risk of BIA-ALCL in our cohort is 1/355 women or 0.311 cases per 1000 person-years (95% CI 0.118 to 0.503). DISCUSSION: This study, the first to evaluate the risk of macro-textured breast implants from a prospective database with long term follow-up, demonstrates that the incidence rate of BIA-ALCL may be higher than previously reported. These results can help inform implant choice for women undergoing breast reconstruction.

Exploring the potential carcinogenic role of arsenic in gallbladder cancer.

Gallbladder cancer (GBC) is an aggressive malignancy, associated with dismal outcomes. Although several risk factors including age, sex, and gallstones have been postulated, epidemiologic determinants of the disease remain largely uncovered. Moreover, the implication of environmental toxicants as possible risk factors is increasingly suspected. Arsenic (As), an established human carcinogen, is a natural contaminant of groundwater and has a geographic distribution similar to GBC incidence. This, combined with As metabolites being partially excreted in bile, raised the hypothesis that As may represent a carcinogenic hazard for the gallbladder. We conducted an analysis of the association between As concentration in groundwater and incidence rates of GBC worldwide in 52 countries. The USA, India, and Taiwan were selected on the basis of availability and quality of data for further investigation at a county-level. Relationships between As levels and GBC incidence were assessed using multivariable linear regression analyses. Analyses revealed significant associations between high As concentrations in groundwater and increased GBC incidences. Among women, correlations were observed worldwide (Spearman = 0.31, P = 0.028), in Taiwan (Spearman = 0.57, P = 0.005) and in India (R = 0.23, P = 0.006). In men, a correlation was observed in India (R = 0.26, P = 0.009) and a modest correlation was identified in the USA (Spearman = 0.14, P = 0.026). These results provide some support to the hypothesis of an association between high exposures to As-contaminated water on GBC, which appeared more prominent in women. Further observational and molecular studies, conducted at the individual level, are required to confirm this association and decipher its nature.

Regulation of miRNA-29c and its downstream pathways in preneoplastic progression of triple-negative breast cancer.

Little is understood about the early molecular drivers of triple-negative breast cancer (TNBC), making the identification of women at risk and development of targeted therapy for prevention significant challenges. By sequencing a TNBC cell line-based breast cancer progression model we have found that miRNA-29c is progressively lost during TNBC tumorigenesis. In support of the tumor suppressive role of miRNA 29c, we found that low levels predict poor overall patient survival and, conversely, that ectopic expression of miRNA-29c in preneoplastic cell models inhibits growth. miRNA-29c exerts its growth inhibitory effects through direct binding and regulation of TGFB-induced factor homeobox 2 (TGIF2), CAMP-responsive element binding protein 5 (CREB5), and V-Akt murine thymoma viral oncogene homolog 3 (AKT3). miRNA-29c regulation of these gene targets seems to be functionally relevant, as TGIF2, CREB5, and AKT3 were able to rescue the inhibition of cell proliferation and colony formation caused by ectopic expression of miRNA-29c in preneoplastic cells. AKT3 is an oncogene of known relevance in breast cancer, and as a proof of principle we show that inhibition of phosphoinositide 3-kinase (PI3K) activity, a protein upstream of AKT3, suppressed proliferation in TNBC preneoplastic cells. We explored additional opportunities for prevention of TNBC by studying the regulation of miRNA-29c and identified DNA methylation to have a role in the inhibition of miRNA-29c during TNBC tumorigenesis. Consistent with these observations, we found 5 aza-cytadine to relieve the suppression of miRNA-29c. Together, these results demonstrate that miRNA-29c loss plays a key role in the early development of TNBC.

Long-Term Safety of Observation in Selected Women Following Core Biopsy Diagnosis of Atypical Ductal Hyperplasia.

PURPOSE: Atypical ductal hyperplasia (ADH) found on core biopsy is associated with an upgrade to carcinoma in 10-30 % of women, thus surgical excision remains the standard of care. This study compares the incidence of breast cancer in women with ADH who were observed with those who underwent surgical excision of the ADH site. METHODS: Our departmental, prospectively maintained registry was reviewed to identify patients with ADH diagnosed by core biopsy. Surgically treated patients were excluded if upstaged to carcinoma following excision for ADH diagnosis. Breast cancer events were classified as index site (site of ADH biopsy), ipsilateral breast unrelated to index site, or contralateral breast. RESULTS: Overall, 175 women met the study criteria; 125 were observed and 50 underwent excision. With a median follow-up of 3 years, 14 breast cancer events were noted in 13 patients. In the surgery group, six women developed breast cancer (12 %), including one bilateral, compared with seven cancers (5.6 %) in the observed group (p = 0.14). Index site events and ipsilateral cancers were the same in both groups [2 vs. 0.8 % (p = 0.49) and 4 versus 4.8 % (p = 1.00), respectively]. All contralateral cancers occurred in the surgical group (8 vs. 0 %; p < 0.01). A prior history of breast cancer was the only variable associated with subsequent breast cancer events (hazard ratio 12.53, 95 % confidence interval 3.30-47.57). CONCLUSION: Observation is appropriate in selected women with ADH on core biopsy. Index site failures are rare and are superseded by cancer risk elsewhere in the breast.

Annexin A1 Preferentially Predicts Poor Prognosis of Basal-Like Breast Cancer Patients by Activating mTOR-S6 Signaling.

INTRODUCTION: Annexin A1 (ANXA1) is an anti-inflammatory protein reported to play a role in cell proliferation and apoptosis, and to be deregulated in breast cancer. The exact role of annexin A1 in the biology of breast cancer remains unclear. We hypothesized that the annexin A1 plays an oncogenic role in basal subtype of breast cancer by modulating key growth pathway(s). METHODS: By mining the Cancer Genome Atlas (TCGA)-Breast Cancer dataset and manipulating annexin A1 levels in breast cancer cell lines, we studied the role of annexin A1 in breast cancer and underlying signaling pathways. RESULTS: Our in-silico analysis of TCGA-breast cancer dataset demonstrated that annexin A1 mRNA expression is higher in basal subtype compared to luminal and HER2 subtypes. Within the basal subtype, patients show significantly poorer overall survival associated with higher expression of annexin A1. In both TCGA patient samples and cell lines, annexin A1 levels were significantly higher in basal-like breast cancer than luminal and Her2/neu-positive breast cancer. Stable annexin A1 knockdown in TNBC cell lines suppressed the mTOR-S6 pathway likely through activation of AMPK but had no impact on the MAPK, c-Met, and EGFR pathways. In a cell migration assay, annexin A1-depleted TNBC cells showed delayed migration as compared to wild-type cells, which could be responsible for poor patient prognosis in basal like breast cancers that are known to express higher annexin A1. CONCLUSIONS: Our data suggest that annexin A1 is prognostic only in patients with basal like breast cancer. This appears to be in part due to the role of annexin A1 in activating mTOR-pS6 pathway.

Suppression of Akt-mTOR pathway-a novel component of oncogene induced DNA damage response barrier in breast tumorigenesis.

DNA damage has been thought to be directly associated with the neoplastic progression by enabling mutations in tumor suppressor genes and activating/and amplifying oncogenes ultimately resulting in genomic instability. DNA damage causes activation of the DNA damage response (DDR) that is an important cellular mechanism for maintaining genomic integrity in the face of genotoxic stress. While the cellular response to genotoxic stress has been extensively studied in cancer models, less is known about the cellular response to oncogenic stress in the premalignant context. In the present study, by using breast tissues samples from women at different risk levels for invasive breast cancer (normal, proliferative breast disease and ductal carcinoma in situ) we found that DNA damage is inversely correlated with risk of invasive breast cancer. Similarly, in MCF10A based in vitro model system where we recapitulated high DNA damage conditions as seen in patient samples by stably cloning in cyclin E, we found that high levels of oncogene induced DNA damage, by triggering inhibition of a major proliferative pathway (AKT), inhibits cell growth and causes cells to die through autophagy. These data suggest that AKT-mTOR pathway is a novel component of oncogene induced DNA damage response in immortalized 'normal-like' breast cells and its suppression may contribute to growth arrest and arrest of the breast tumorigenesis.

Lubiprostone activates Cl- secretion via cAMP signaling and increases membrane CFTR in the human colon carcinoma cell line, T84.

BACKGROUND: Lubiprostone, used clinically (b.i.d.) to treat constipation, has been reported to increase transepithelial Cl(-) transport in T84 cells by activating ClC-2 channels. AIM: To identify the underlying signaling pathway, we explored the effects of short-term and overnight lubiprostone treatment on second messenger signaling and Cl(-) transport. METHODS: Cl(-) transport was assessed either as I(sc) across T84 monolayers grown on Transwells and mounted in Ussing chambers or by the iodide efflux assay. [cAMP](i) was measured by enzyme immunoassay, and [Ca(2+)](i) by Fluo-3 fluorescence. Quantitation of apical cell surface CFTR protein levels was assessed by Western blotting and biotinylation with the EZ-Link Sulfo-NHS-LC-LC-Biotin. ClC-2 mRNA level was studied by RT-PCR. RESULTS: Lubiprostone and the cAMP stimulator, forskolin, caused comparable and maximal increases of I(sc) in T84 cells. The I(sc) effects of lubiprostone and forskolin were each suppressed if the tissue had previously been treated with the other agent. These responses were unaltered even if the monolayers were treated with lubiprostone overnight. Lubiprostone-induced increases in iodide efflux were ~80% of those obtained with forskolin. Lubiprostone increased [cAMP](i). H89, bumetanide, or CFTR(inh)-172 greatly attenuated lubiprostone-stimulated Cl(-) secretion, whereas the ClC-2 inhibitor CdCl(2) did not. Compared to controls, FSK-treatment increased membrane-associated CFTR by 1.9 fold, and lubiprostone caused a 2.6-fold increase in apical membrane CFTR as seen by immunoblotting following cell surface biotinylation. CONCLUSIONS: Lubiprostone activates Cl(-) secretion in T84 cells via cAMP, protein kinase A, and by increasing apical membrane CFTR protein.