Carrier-free mRNA vaccine induces robust immunity against SARS-CoV-2 in mice and non-human primates without systemic reactogenicity.

Carrier-free naked mRNA vaccines may reduce the reactogenicity associated with delivery carriers; however, their effectiveness against infectious diseases has been suboptimal. To boost efficacy, we targeted the skin layer rich in antigen-presenting cells (APCs) and utilized a jet injector. The jet injection efficiently introduced naked mRNA into skin cells, including APCs in mice. Further analyses indicated that APCs, after taking up antigen mRNA in the skin, migrated to the lymph nodes (LNs) for antigen presentation. Additionally, the jet injection provoked localized lymphocyte infiltration in the skin, serving as a physical adjuvant for vaccination. Without a delivery carrier, our approach confined mRNA distribution to the injection site, preventing systemic mRNA leakage and associated systemic proinflammatory reactions. In mouse vaccination, the naked mRNA jet injection elicited robust antigen-specific antibody production over 6 months, along with germinal center formation in LNs and the induction of both CD4- and CD8-positive T cells. By targeting the SARS-CoV-2 spike protein, this approach provided protection against viral challenge. Furthermore, our approach generated neutralizing antibodies against SARS-CoV-2 in non-human primates at levels comparable to those observed in mice. In conclusion, our approach offers a safe and effective option for mRNA vaccines targeting infectious diseases.

Preclinical and first-in-human phase I studies of KW-2450, an oral tyrosine kinase inhibitor with insulin-like growth factor receptor-1/insulin receptor selectivity.

Numerous solid tumors overexpress or have excessively activated insulin-like growth factor receptor-1 (IGF-1R). We summarize preclinical studies and the first-in-human study of KW-2450, an oral tyrosine kinase inhibitor with IGF-1R and insulin receptor (IR) inhibitory activity. Preclinical activity of KW-2450 was evaluated in various in vitro and in vivo models. It was then evaluated in a phase I clinical trial in 13 patients with advanced solid tumors (NCT00921336). In vitro, KW-2450 inhibited human IGF-1R and IR kinases (IC50 7.39 and 5.64 nmol/L, respectively) and the growth of various human malignant cell lines. KW-2450 40 mg/kg showed modest growth inhibitory activity and inhibited IGF-1-induced signal transduction in the murine HT-29/GFP colon carcinoma xenograft model. The maximum tolerated dose of KW-2450 was 37.5 mg once daily continuously; dose-limiting toxicity occurred in two of six patients at 50 mg/day (both grade 3 hyperglycemia) and in one of seven patients at 37.5 mg/day (grade 3 rash). Four of 10 evaluable patients showed stable disease. Single-agent KW-2450 was associated with modest antitumor activity in heavily pretreated patients with solid tumors and is being further investigated in combination therapy with lapatinib/letrozole in patients with human epidermal growth factor receptor 2-postive metastatic breast cancer.

Dose-intensified chemotherapy alone or in combination with mogamulizumab in newly diagnosed aggressive adult T-cell leukaemia-lymphoma: a randomized phase II study.

This multicentre, randomized, phase II study was conducted to examine whether the addition of mogamulizumab, a humanized anti-CC chemokine receptor 4 antibody, to mLSG15, a dose-intensified chemotherapy, further increases efficacy without compromising safety of patients with newly diagnosed aggressive adult T-cell leukaemia-lymphoma (ATL). Patients were assigned 1:1 to receive mLSG15 plus mogamulizumab or mLSG15 alone. The primary endpoint was the complete response rate (%CR); secondary endpoints included the overall response rate (ORR) and safety. The %CR and ORR in the mLSG15-plus-mogamulizumab arm (n = 29) were 52% [95% confidence interval (CI), 33-71%] and 86%, respectively; the corresponding values in the mLSG15 arm (n = 24) were 33% (95% CI, 16-55%) and 75%, respectively. Grade ≥ 3 treatment-emergent adverse events, including anaemia, thrombocytopenia, lymphopenia, leucopenia and decreased appetite, were observed more frequently (≥10% difference) in the mLSG15-plus-mogamulizumab arm. Several adverse events, including skin disorders, cytomegalovirus infection, pyrexia, hyperglycaemia and interstitial lung disease, were observed only in the mLSG15-plus-mogamulizumab arm. Although the combination strategy showed a potentially less favourable safety profile, a higher %CR was achieved, providing the basis for further investigation of this novel treatment for newly diagnosed aggressive ATL. This study was registered at ClinicalTrials.gov, identifier: NCT01173887.

A phase II trial of a selective c-Met inhibitor tivantinib (ARQ 197) monotherapy as a second- or third-line therapy in the patients with metastatic gastric cancer.

BACKGROUND: Tivantinib is a selective, non-ATP competitive, small-molecule inhibitor of c-Met and is under development in several cancers including non-small cell lung and hepatocellular carcinoma. Activation of c-Met has been frequently found in metastatic gastric cancer (MGC) and is associated with poor prognosis. In this single-arm study, we evaluated the efficacy of tivantinib monotherapy in Asian patients with previously treated MGC. This is the first clinical report from the trials evaluating the efficacy of a selective c-Met inhibitor for MGC. PATIENTS AND METHODS: Eligibility criteria included: MGC with at least one measurable lesion; 1 or 2 prior chemotherapy regimens; and ECOG PS 0 or 1. Tivantinib was daily administered orally. The primary endpoint was the disease control rate (DCR). Pre-treatment tumor tissue was collected to evaluate the biomarkers related to efficacy. RESULTS: Thirty patients, including 12 patients with prior gastrectomy, received tivantinib: median age 62.5 years; ECOG PS 0/1 (8/22); 1/2 prior regimen (16/14). No objective response was observed, and DCR was 36.7 %. Median progression-free survival was 43 days (95 % CI: 29.0-92.0). Grade 3 or 4 adverse events occurred in 13 patients (43.3 %), in whom neutropenia (N = 4) and anemia (N = 4) were recognized as drug-related. c-Met gene amplification was observed in 2 patients (6.9 %). No obvious relationship was identified between efficacy and biomarkers including gene amplification of c-Met, expression of c-Met, p-Met and HGF. CONCLUSION: Tivantinib as a monotherapy showed a modest efficacy in previously treated MGC, and further studies taking account of predictive biomarkers and/or combination with other chemotherapy may be needed in MGC.

Synthetic studies on mitotic kinesin Eg5 inhibitors: synthesis and structure-activity relationships of novel 2,4,5-substituted-1,3,4-thiadiazoline derivatives.

The 2,4,5-substituted-1,3,4-thiadiazoline derivative 1a has been identified as a new class of mitotic kinesin Eg5 inhibitor. With the aim of enhancement of the mitotic phase accumulation activity, structure optimization of side chains at the 2-, 4-, and 5-positions of the 1,3,4-thiadiazoline ring of 1a was performed. The introduction of sulfonylamino group at the side chain at the 5-position and bulky acyl group at the 2- and 4-position contributed to a significant increase in the mitotic phase accumulation activity and Eg5 inhibitory activity. As a result, a series of optically active compounds exhibited an increased antitumor activity in a human ovarian cancer xenograft mouse model that was induced by oral administration.

Reactivation of hepatitis B virus in a patient with adult T-cell leukemia-lymphoma receiving the anti-CC chemokine receptor 4 antibody mogamulizumab.

The introduction of molecularly targeted drugs has increased the risk of reactivation of hepatitis B virus (HBV), which is a potentially fatal complication following anticancer chemotherapy even in patients who have previously resolved their HBV infection. CC chemokine receptor 4 (CCR4) has been identified as a novel molecular target in antibody therapy for patients with adult T-cell leukemia-lymphoma (ATL) and peripheral T-cell lymphoma, and the humanized anti-CCR4 monoclonal antibody mogamulizumab has been developed. We reported HBV reactivation of an ATL patient with previously resolved HBV infection after mogamulizumab treatment in a dose-finding study for this antibody. Our retrospective analysis using preserved samples also revealed the detailed kinetics of HBV DNA levels before and just after HBV reactivation.

Stevens-Johnson Syndrome associated with mogamulizumab treatment of adult T-cell leukemia / lymphoma.

We report an adult T-cell leukemia/lymphoma patient suffering from Stevens-Johnson Syndrome (SJS) during mogamulizumab (humanized anti-CCR4 monoclonal antibody) treatment. There was a durable significant reduction of the CD4(+) CD25(high) FOXP3(+) regulatory T (Treg) cell subset in the patient's PBMC, and the affected inflamed skin almost completely lacked FOXP3-positive cells. This implies an association between reduction of the Treg subset by mogamulizimab and occurrence of SJS. The present case should contribute not only to our understanding of human pathology resulting from therapeutic depletion of Treg cells, but also alert us to the possibility of immune-related severe adverse events such as SJS when using mogamulizumab. We are currently conducting a clinical trial of mogamulizumab for CCR4-negative solid cancers (UMIN000010050), specifically aiming to deplete Treg cells.

Phase I study of highly selective inhibitor of VEGFR tyrosine kinase, tivozanib, in Japanese patients with solid tumors.

Tivozanib is a potent and selective inhibitor of vascular endothelial growth factor receptor (VEGFR) tyrosine kinases. A previous clinical trial in the EU and USA indicated that tivozanib at the maximum tolerated dose of 1.5 mg/day showed an antitumor activity in patients with renal cell carcinoma. This Japanese phase I study was designed to determine the recommended phase II dose of tivozanib for Japanese patients; secondary objectives included pharmacokinetic/pharmacodynamic profiles and preliminary efficacy. Daily treatment with tivozanib in a 3-weeks-on/1-week-off cycle was examined in nine Japanese patients with advanced solid tumors in the 3 + 3 design (Level 1, 1.0 mg; Level 2, 1.5 mg). No dose-limiting toxicity was observed throughout the study, and the maximum tolerated dose was not reached. The most commonly observed drug-related adverse events were diarrhea, dysphonia, rash, thyroid stimulating hormone increase, and with severity grade ≥3, hand-foot skin reaction, hypertension, and proteinuria. Those adverse events were generally well-manageable and mostly resolved within the tolerability evaluation period. Serum exposure to tivozanib resulted in t1/2 of more than >60 h. Increase of plasma VEGF and decrease of plasma VEGFR-1 and VEGFR-2 were observed 1-3 weeks after tivozanib treatment. Although no complete or partial response was observed, long-term stable disease continuing more than 170 days was observed in three renal cell carcinoma patients who had failed prior VEGFR inhibitors. In conclusion, 1.5 mg/day of tivozanib in a 3-weeks-on/1-week-off setting was tolerable in Japanese patients, and was recommended for further clinical trials in the Japanese population. Clinical trial Registration No: JapicCTI-090854.

Translational nanomedicine potentiates immunotherapy in sarcoma by normalizing the microenvironment.

Nanocarrier-based chemo-immunotherapy has succeeded in clinical trials and understanding its effect on the tumor microenvironment could facilitate development of strategies to increase efficacy of these regimens further. NC-6300 (epirubicin micelle) demonstrates anti-tumor activity in sarcoma patients, but whether it is combinable with immune checkpoint inhibition is unclear. Here, we tested NC-6300 combined with anti-PD-L1 antibody in mouse models of osteosarcoma and fibrosarcoma. We found that sarcoma responds to NC-6300 in a dose-dependent manner, while anti-PD-L1 efficacy is potentiated even at a dose of NC-6300 less than 10% of the maximum tolerated dose. Furthermore, NC-6300 is more effective than the maximum tolerated dose of doxorubicin in increasing the tumor growth delay induced by anti-PD-L1 antibody. We investigated the mechanism of action of this combination. NC-6300 induces immunogenic cell death and its effect on the efficacy of anti-PD-L1 antibody is dependent on T cells. Also, NC-6300 normalized the tumor microenvironment (i.e., ameliorated pathophysiology towards normal phenotype) as evidenced through increased blood vessel maturity and reduced fibrosis. As a result, the combination with anti-PD-L1 antibody increased the intratumor density and proliferation of T cells. In conclusion, NC-6300 potentiates immune checkpoint inhibition in sarcoma, and normalization of the tumor microenvironment should be investigated when developing nanocarrier-based chemo-immunotherapy regimens.

Genetically engineered humanized anti-ganglioside GM2 antibody against multiple organ metastasis produced by GM2-expressing small-cell lung cancer cells.

Small-cell lung cancer (SCLC) grows rapidly and metastasizes to multiple organs. We examined the antimetastatic effects of the humanized anti-ganglioside GM2 (GM2) antibodies, BIW-8962 and KM8927, compared with the chimeric antibody KM966, in a SCID mouse model of multiple organ metastases induced by GM2-expressing SCLC cells. BIW-8962 and KM8927 induced higher antibody-dependent cellular cytotoxicity and complement-dependent cytotoxicity than KM966 against the GM2-expressing SCLC cell line SBC-3 in vitro. These humanized antibodies inhibited the production of multiple organ metastases, increased the number of apoptotic cells, and prolonged the survival of the SCID mice. Histological analyses using clinical specimens showed that SCLC cells expressed GM2. These findings suggest that humanized anti-GM2 antibodies could be therapeutically useful for controlling multiple organ metastases of GM2-expressing SCLC.

A pharmacodynamic study of the FLT3 inhibitor KW-2449 yields insight into the basis for clinical response.

Internal tandem duplication mutations of FLT3 (FLT3/ITD mutations) are common in acute myeloid leukemia (AML) and confer a poor prognosis. This would suggest that FLT3 is an ideal therapeutic target, but FLT3 targeted therapy has produced only modest benefits in clinical trials. Due to technical obstacles, the assessment of target inhibition in patients treated with FLT3 inhibitors has been limited and generally only qualitative. KW-2449 is a novel multitargeted kinase inhibitor that induces cytotoxicity in Molm14 cells (which harbor an FLT3/ITD mutation). The cytotoxic effect occurs primarily at concentrations sufficient to inhibit FLT3 autophosphorylation to less than 20% of its baseline. We report here correlative data from a phase 1 trial of KW-2449, a trial in which typical transient reductions in the peripheral blast counts were observed. Using quantitative measurement of FLT3 inhibition over time in these patients, we confirmed that FLT3 was inhibited, but only transiently to less than 20% of baseline. Our results suggest that the failure to fully inhibit FLT3 in sustained fashion may be an underlying reason for the minimal success of FLT3 inhibitors to date, and stress the importance of confirming in vivo target inhibition when taking a targeted agent into the clinical setting.

KW-2449, a novel multikinase inhibitor, suppresses the growth of leukemia cells with FLT3 mutations or T315I-mutated BCR/ABL translocation.

KW-2449, a multikinase inhibitor of FLT3, ABL, ABL-T315I, and Aurora kinase, is under investigation to treat leukemia patients. In this study, we examined its possible modes of action for antileukemic effects on FLT3-activated, FLT3 wild-type, or imatinib-resistant leukemia cells. KW-2449 showed the potent growth inhibitory effects on leukemia cells with FLT3 mutations by inhibition of the FLT3 kinase, resulting in the down-regulation of phosphorylated-FLT3/STAT5, G(1) arrest, and apoptosis. Oral administration of KW-2449 showed dose-dependent and significant tumor growth inhibition in FLT3-mutated xenograft model with minimum bone marrow suppression. In FLT3 wild-type human leukemia, it induced the reduction of phosphorylated histone H3, G(2)/M arrest, and apoptosis. In imatinib-resistant leukemia, KW-2449 contributed to release of the resistance by the simultaneous down-regulation of BCR/ABL and Aurora kinases. Furthermore, the antiproliferative activity of KW-2449 was confirmed in primary samples from AML and imatinib-resistant patients. The inhibitory activity of KW-2449 is not affected by the presence of human plasma protein, such as alpha1-acid glycoprotein. These results indicate KW-2449 has potent growth inhibitory activity against various types of leukemia by several mechanisms of action. Our studies indicate KW-2449 has significant activity and warrants clinical study in leukemia patients with FLT3 mutations as well as imatinib-resistant mutations.

Engineered therapeutic antibodies with improved effector functions.

In the past decade, more than 20 therapeutic antibodies have been approved for clinical use and many others are now at the clinical and preclinical stage of development. Fragment crystallizable (Fc)-dependent antibody functions, such as antibody-dependent cell-mediated cytotoxicity (ADCC), complement-dependent cytotoxicity (CDC), and a long half-life, have been suggested as important clinical mechanisms of therapeutic antibodies. These functions are primarily triggered through direct interaction of the Fc domain with its corresponding receptors: FcgammaRIIIa for ADCC, C1q for CDC, and neonatal Fc receptor for prolongation of the clearance rate. However, current antibody therapy still faces the critical issues of insufficient efficacy and the high cost of the therapeutic agents. A possible solution to these issues could be to engineer antibody molecules to enhance their antitumor activity, leading to improved therapeutic outcomes and reduced doses. Here, we review advanced Fc engineering approaches for the enhancement of effector functions, some of which are now ready for evaluation of their effectiveness in clinical trials.

Novel and orally active 5-(1,3,4-oxadiazol-2-yl)pyrimidine derivatives as selective FLT3 inhibitors.

5-(1,3,4-Oxadiazol-2-yl)pyrimidine derivative 1 was identified as a new class of FLT3 inhibitor from our compound library. With the aim of enhancement of antitumor activity of 2 prepared by minor modification of 1, structure optimization of side chains at the 2-, 4-, and 5-positions of the pyrimidine ring of 2 was performed to improve the metabolic stability. Introduction of polar substituents on the 1,3,4-oxadiazolyl group contributed to a significant increase in the metabolic stability. As a result, a series of compounds showed increased efficacy against MOLM-13 xenograft model in mice by oral administration.

A novel FLT3 inhibitor FI-700 selectively suppresses the growth of leukemia cells with FLT3 mutations.

PURPOSE: The aim of this study was to evaluate the antileukemia activity of a novel FLT3 kinase inhibitor, FI-700. EXPERIMENTAL DESIGN: The antileukemia activity of FI-700 was evaluated in human leukemia cell lines, mutant or wild-type (Wt)-FLT3-expressing mouse myeloid precursor cell line, 32D and primary acute myeloid leukemia cells, and in xenograft or syngeneic mouse leukemia models. RESULTS: FI-700 showed a potent IC(50) value against FLT3 kinase at 20 nmol/L in an in vitro kinase assay. FI-700 showed selective growth inhibition against mutant FLT3-expressing leukemia cell lines and primary acute myeloid leukemia cells, whereas it did not affect the FLT3 ligand (FL)-driven growth of Wt-FLT3-expressing cells. These antileukemia activities were induced by the significant dephosphorylations of mutant FLT3 and STAT5, which resulted in G(1) arrest of the cell cycle. Oral administration of FI-700 induced the regression of tumors in a s.c. tumor xenograft model and increased the survival of mice in an i.v. transplanted model. Furthermore, FI-700 treatment eradicated FLT3/ITD-expressing leukemia cells, both in the peripheral blood and in the bone marrow. In this experiment, the depletion of FLT3/ITD-expressing cells by FI-700 was more significant than that of Ara-C, whereas bone marrow suppression by FI-700 was lower than that by Ara-C. CONCLUSIONS: FI-700 is a novel and potent FLT3 inhibitor with promising antileukemia activity.

Preclinical and phase I clinical studies of KW-2450, a dual IGF-1R/IR tyrosine kinase inhibitor, in combination with lapatinib and letrozole.

BACKGROUND: KW-2450 is an oral dual insulin-like growth factor-1 receptor/insulin receptor tyrosine kinase inhibitor. We investigated the in vitro and in vivo preclinical activity of KW-2450 plus lapatinib and letrozole and conducted a phase I trial of the triple-drug combination in one male and 10 postmenopausal female patients with advanced/metastatic hormone receptor-positive, human epidermal growth factor receptor 2 (HER2)-positive breast cancer. METHODS: A series of in vitro and in vivo animal studies was undertaken of KW-2450 in combination with lapatinib and hormonal agents. The phase I trial was conducted to establish the safety, tolerability, and recommended phase II dose (RP2D) of KW-2450 administered in combination with lapatinib and letrozole. RESULTS: Preclinical studies showed KW-2450 and lapatinib act synergistically to induce in vitro apoptosis and inhibit growth of HER2-positive MDA-MB-361 and BT-474 breast cancer cell lines. This combined effect was confirmed in vivo using the MDA-MB-361 xenograft model. KW-2450 showed synergistic in vitro growth inhibition with letrozole and 4-hydroxytamoxifen in ER-positive MCF-7 breast cancer cells and MCF-7-Ac1 aromatase-transfected MCF-7 cells. In the phase I study, dose-limiting toxicity (DLT; grade 3 rash and grade 3 hyperglycemia, respectively) occurred in two of three patients at the dose of KW-2450 25 mg/day plus lapatinib 1500 mg/day and letrozole 2.5 mg/day. The RP2D of the triple-drug combination was established as KW-2450 25 mg/day, lapatinib 1250 mg/day, and letrozole 2.5 mg/day with no DLT at this dose level. CONCLUSIONS: The proposed phase II study of the RP2D for the triple-drug combination did not progress because of anticipated difficulty in patient enrollment and further clinical development of KW-2450 was terminated.

Telomerase inhibitors identified by a forward chemical genetics approach using a yeast strain with shortened telomere length.

Telomerase has been proposed as a selective target for cancer chemotherapy. We established a forward chemical genetics approach using a yeast strain with shortened telomere length. Since this strain rapidly enters cell senescence in the absence of active telomerase, compounds that induce selective growth defects against telomere-shortened yeast could be candidates for drugs acting on telomeres and telomerase. We screened our microbial products library and identified three structurally unrelated antibiotics, chrolactomycin, UCS1025A, and radicicol, as active compounds. Detailed analysis showed that chrolactomycin inhibited human telomerase in a cell-free assay as well as in a cellular assay. Long-term culture of cancer cells with chrolactomycin revealed population-doubling-dependent antiproliferative activity accompanied by telomere shortening. These results suggest that chrolactomycin is a telomerase inhibitor, and that the yeast-based assay is useful for discovering the small molecules acting on human telomerase.

Improved formulations of antisense oligodeoxynucleotides using wrapped liposomes.

Previously, we demonstrated that wrapping dextran fluorescein anionic/cationic lipid complexes with neutral lipids produced a stable formulation that markedly increased the duration of the compound in plasma after intravenous administration to rats. The improved drug-delivery properties of the wrapped liposomes (WL) relative to other formulations suggested that this technology could offer important advantages for the administration of other polyanionic drugs, including antisense oligodeoxynucleotides (ODN). In the present study, we investigated the value of WL for formulating fluorescence-labeled phosphorothioated ODN (F-ODN). WL encapsulating F-ODN/cationic lipid complexes were prepared efficiently using similar methodology to that used in our earlier study. Studies confirmed that these WL were stable in vitro. Following intravenous administration to mice, free F-ODN and naked F-ODN/cationic lipid complexes were rapidly eliminated whereas administration of the WL resulted in high blood concentrations of drug that were maintained for several hours. Additional studies were conducted in mice that were inoculated with tumor cells (Caki-1 xenograft model, human kidney); in these experiments, intravenous administration of WL delivered 13 times more F-ODN to the tumor site than achieved after injection of free F-ODN.

A neutralizing anti-fibroblast growth factor 8 monoclonal antibody shows potent antitumor activity against androgen-dependent mouse mammary tumors in vivo.

PURPOSE: Fibroblast growth factor 8b (FGF8b) has been implicated in oncogenesis of sex hormone-related malignancies. A murine monoclonal anti-FGF8 antibody, KM1334, has been raised against a FGF8b-derived peptide and shown to neutralize FGF8b activity in an androgen-dependent mouse mammary cell line (SC-3) in vitro growth. The purpose of this study was to evaluate KM1334 as a therapeutic agent for FGF8-dependent cancer. EXPERIMENTAL DESIGN: Specificity and neutralizing activity of KM1334 were examined in vitro. In vivo therapeutic studies were done in nude mice bearing SC-3 tumors s.c. RESULTS: KM1334 recognized FGF8b and FGF8f specifically out of four human FGF8 isoforms and showed little binding to other members of FGF family. Neutralizing activity of KM1334 was confirmed by both blocking of FGF8b binding to its three receptors (FGFR2IIIc, FGFR3IIIc, and FGFR4) and FGF8b-induced phosphorylation of FGFR substrate 2alpha and extracellular signal-regulated kinase 1/2 in SC-3 cells. The in vitro inhibitory effect could be extended to in vivo tumor models, where KM1334 caused rapid regression of established SC-3 tumors in nude mice. This rapid regression of tumors after KM1334 treatment was explained by two independent mechanisms: (a) decreased DNA synthesis, as evidenced by a decrease in uptake of 5-bromo-2'-deoxyuridine, and (b) induction of apoptosis as shown by the terminal deoxynucleotidyl transferase-mediated nick end labeling assay. CONCLUSIONS: KM1334 possesses strong blocking activity in vitro and antitumor activity in vivo and therefore may be an effective therapeutic candidate for the treatment of cancers that are dependent on FGF8b signaling for growth and survival.

Estrogen sulfotransferase and steroid sulfatase in human breast carcinoma.

Estrogen sulfotransferase (EST; SULT 1E1 or STE gene) sulfonates estrogens to inactive estrogen sulfates, whereas steroid sulfatase (STS) hydrolyzes estrone sulfate to estrone. Both EST and STS have been suggested to play important roles in regulating the in situ production of estrogens in human breast carcinoma tissues. However, the expression of EST has not been examined in breast carcinoma tissues, and the biological significance of EST and STS remains unknown. Therefore, in this study, we examined the expression of EST and STS in 35 specimens of human breast carcinoma tissues using immunohistochemistry, reverse transcription-PCR (RT-PCR), and enzymatic assay. EST and STS immunoreactivity was also correlated with various clinicopathological parameters, including prognosis to examine the biological significance of these enzymes in 113 breast carcinomas. EST and STS immunoreactivity was detected in carcinoma cells and significantly associated with their mRNA levels (P = 0.0027 and 0.0158, respectively), as measured by RT/real-time PCR, and enzymatic activities (P = 0.0005 and 0.0089, respectively) in 35 breast carcinomas. In breast cancer tissues examined by laser capture microdissection/RT-PCR analyses, the mRNA for EST was localized in both carcinoma and intratumoral stromal cells, whereas that of STS was detected only in carcinoma cells. Of the 113 invasive ductal carcinomas examined in this study, EST and STS immunoreactivity was detected in 50 and 84 cases (44.2 and 74.3%), respectively. In these cases, EST immunoreactivity was inversely correlated with tumor size (P = 0.003) or lymph node status (P = 0.0027). In contrast, STS immunoreactivity was significantly correlated with tumor size (P = 0.0047). Moreover, EST immunoreactivity was significantly associated with a decreased risk of recurrence or improved prognosis by both uni (P = 0.0044, and 0.0026, respectively) and multivariate (P = 0.0429 and 0.0149, respectively) analyses. STS immunoreactivity, however, was significantly associated with an increased risk of recurrence (P = 0.0118) and worsened prognosis (P = 0.0325) by univariate analysis. Results from our present study suggest that immunoreactivities for both EST and STS are associated with their mRNA level and enzymatic activity and that EST immunoreactivity is considered to be a potent prognostic factor in human breast carcinoma.