Bintrafusp alfa and chemotherapy as first-line treatment in biliary tract cancer: A randomized phase 2/3 trial.

BACKGROUND AND AIMS: We compared the safety and efficacy of bintrafusp alfa (BA) in combination with gemcitabine+cisplatin (GemCis), to those of GemCis alone, in patients with biliary tract cancer. APPROACH AND RESULTS: This randomized, double-blind, placebo-controlled, adaptive design phase 2/3 trial (NCT04066491) included adults who are treatment-naive with locally advanced/metastatic biliary tract cancer. Patients (N = 297) were randomized to receive an IV infusion of BA (2400 mg once/3 wk) plus GemCis (gemcitabine 1000 mg/m 2 +cisplatin 25 mg/m 2 on days 1 and 8/3 wk; 8 cycles) (BA group, n = 148) or placebo+GemCis (placebo group, n = 149). The primary end point was overall survival (OS). For adaptation analysis (phase 2-phase 3; data cutoff: May 20, 2021), efficacy was assessed in the first 150 patients who were antibiotic-naive when 80 progression-free survival events had occurred and ≥ 19 weeks of follow-up had been completed (BA, n = 73; placebo, n = 77). Median OS (95% CI) for the BA (11.5 mo [9.3-not estimable]) and placebo (11.5 mo [10.0-not estimable]) groups was comparable (hazard ration 1.23 [95% CI 0.66-2.28]; p = 0.7394); OS data maturity was 27.2% (41 events/151 patients). The most common grade ≥3 treatment-related adverse event was anemia (BA, 26.0%; placebo, 22.8%). Bleeding adverse events were reported more frequently in the BA group (28.8%) versus the placebo group (7.4%). Deaths within 60 days of the first dose were reported in 7.5% and 1.3% of patients in the BA and placebo groups, respectively. CONCLUSIONS: BA+GemCis did not provide a clinically meaningful benefit compared with GemCis alone as first-line treatment for biliary tract cancer, and the study was discontinued early (terminated: August 20, 2021).

Model-informed approach for risk management of bleeding toxicities for bintrafusp alfa, a bifunctional fusion protein targeting TGF-ß and PD-L1.

PURPOSE: Bintrafusp alfa (BA) is a bifunctional fusion protein composed of the extracellular domain of the transforming growth factor-ß (TGF-ß) receptor II fused to a human immunoglobulin G1 antibody blocking programmed death ligand 1 (PD-L1). The recommended phase 2 dose (RP2D) was selected based on phase 1 efficacy, safety, and pharmacokinetic (PK)-pharmacodynamic data, assuming continuous inhibition of PD-L1 and TGF-ß is required. Here, we describe a model-informed dose modification approach for risk management of BA-associated bleeding adverse events (AEs). METHODS: The PK and AE data from studies NCT02517398, NCT02699515, NCT03840915, and NCT04246489 (n = 936) were used. Logistic regression analyses were conducted to evaluate potential relationships between bleeding AEs and BA time-averaged concentration (Cavg), derived using a population PK model. The percentage of patients with trough concentrations associated with PD-L1 or TGF-ß inhibition across various dosing regimens was derived. RESULTS: The probability of bleeding AEs increased with increasing Cavg; 50% dose reduction was chosen based on the integration of modeling and clinical considerations. The resulting AE management guidance to investigators regarding temporary or permanent treatment discontinuation was further refined with recommendations on restarting at RP2D or at 50% dose, depending on the grade and type of bleeding (tumoral versus nontumoral) and investigator assessment of risk of additional bleeding. CONCLUSION: A pragmatic model-informed approach for management of bleeding AEs was implemented in ongoing clinical trials of BA. This approach is expected to improve benefit-risk profile; however, its effectiveness will need to be evaluated based on safety data generated after implementation.

Bintrafusp Alfa, a Bifunctional Fusion Protein Targeting TGFß and PD-L1, in Patients with Esophageal Squamous Cell Carcinoma: Results from a Phase 1 Cohort in Asia.

BACKGROUND: Patients with esophageal squamous cell carcinoma (SCC) have limited treatment options. Blocking transforming growth factor-ß (TGFß), which can be overexpressed in these tumors, may enhance responses to programmed cell death protein 1/programmed death-ligand 1 [PD-(L)1] inhibitors. Bintrafusp alfa is a first-in-class bifunctional fusion protein composed of the extracellular domain of the TGFß receptor II (TGFßRII) (a TGFß "trap") fused to a human IgG1 monoclonal antibody blocking PD-L1. OBJECTIVE: The objective of this study was to investigate the safety and efficacy of bintrafusp alfa in Asian patients with pretreated, PD-L1-unselected esophageal SCC. PATIENTS AND METHODS: In a phase 1 study, Asian patients with pretreated esophageal SCC received bintrafusp alfa 1200 mg every 2 weeks until disease progression, unacceptable toxicity, or withdrawal. The primary endpoint was safety/tolerability with a goal of exploring clinical activity. RESULTS: By the database cutoff of August 24, 2018, 30 patients (76.7% had two or more prior anticancer regimens) received bintrafusp alfa for a median of 6.1 weeks; two remained on treatment. Nineteen patients (63.3%) had treatment-related adverse events, seven (23.3%) with grade 3/4 events, and there were no treatment-related deaths. The confirmed objective response rate (ORR) per independent review was 10.0% (95% confidence interval [CI] 2.1-26.5); responses lasted 2.8-8.3 + months. All responses occurred in immune-excluded tumors. Investigator-assessed confirmed ORR was 20.0% (95% CI 7.7-38.6). Median overall survival was 11.9 months (95% CI 5.7-not reached). CONCLUSIONS: Bintrafusp alfa demonstrated a manageable safety profile and efficacy in Asian patients with pretreated esophageal SCC. CLINICAL TRIALS REGISTRATION: NCT02699515.

Phase I study of bintrafusp alfa, a bifunctional fusion protein targeting TGF-ß and PD-L1, in patients with pretreated biliary tract cancer.

BACKGROUND: Patients with biliary tract cancer (BTC) have poor prognosis with few treatment options. Bintrafusp alfa, a first-in-class bifunctional fusion protein composed of the extracellular domain of the transforming growth factor (TGF)-ßRII receptor (a TGF-ß 'trap') fused to a human IgG1 antibody blocking programmed death ligand 1 (PD-L1), has shown clinical efficacy in multiple solid tumors. METHODS: In this phase I, open-label trial expansion cohort, Asian patients with BTC whose disease progressed after first-line chemotherapy received bintrafusp alfa 1200 mg every 2 weeks until disease progression, unacceptable toxicity, or withdrawal. The primary endpoint is safety/tolerability, while the secondary endpoints include best overall response per Response Evaluation Criteria in Solid Tumors version 1.1. RESULTS: As of August 24, 2018, 30 patients have received bintrafusp alfa for a median of 8.9 (IQR 5.7-32.1) weeks; 3 patients remained on treatment for >59.7 weeks. Nineteen (63%) patients experienced treatment-related adverse events (TRAEs), most commonly rash (17%), maculopapular rash and fever (13% each), and increased lipase (10%). Eleven (37%) patients had grade ≥3 TRAEs; three patients had grade 5 events (septic shock due to bacteremia, n=1; interstitial lung disease (reported term: interstitial pneumonitis), n=2). The objective response rate was 20% (95% CI 8 to 39) per independent review committee (IRC), with five of six responses ongoing (12.5+ to 14.5+ months) at data cut-off. Two additional patients with durable stable disease had a partial response per investigator. Median progression-free survival assessed by IRC and overall survival were 2.5 months (95% CI 1.3 to 5.6) and 12.7 months (95% CI 6.7 to 15.7), respectively. Clinical activity was observed irrespective of PD-L1 expression and microsatellite instability-high status. CONCLUSIONS: Bintrafusp alfa had clinical activity in Asian patients with pretreated BTC, with durable responses. Based on these results, bintrafusp alfa is under further investigation in patients with BTC (NCT03833661 and NCT04066491). TRIAL REGISTRATION NUMBER: NCT02699515.

Safety and Tolerability of Bintrafusp Alfa, a Bifunctional Fusion Protein Targeting TGFß and PD-L1, in Asian Patients with Pretreated Recurrent or Refractory Gastric Cancer.

PURPOSE: Patients with advanced gastric/gastroesophageal junction cancer (GC/GEJC) have limited treatment options after first-line therapy. Bintrafusp alfa is a first-in-class bifunctional fusion protein composed of the extracellular domain of the TGFßRII receptor (a TGFß "trap") fused to a human IgG1 antibody against programmed death ligand 1 (PD-L1), potentially offering a new treatment approach for these patients. We report results for bintrafusp alfa in GC/GEJC. PATIENTS AND METHODS: Asian patients with recurrent GC/GEJC for whom standard therapy does not exist or for whom standard therapy has failed enrolled in this expansion cohort of an ongoing phase I trial and received bintrafusp alfa 1,200 mg once every 2 weeks until disease progression, unacceptable toxicity, or withdrawal. The primary objective was to assess safety/tolerability. RESULTS: By July 23, 2018, 31 heavily pretreated patients received bintrafusp alfa for a median of 10.1 weeks; 3 patients remained on treatment. Six patients (19%) experienced grade 3 treatment-related adverse events (AE); no grade 4 events occurred. One on-treatment death occurred (sudden death); rupture of a preexisting thoracic aortic aneurysm was the suspected cause. Ten patients (32%) had immune-related AEs. The confirmed objective response rate per independent review committee was 16%; disease control rate was 26%. Median duration of response was 8.7 months (range, 2.4-12.4+). Responses occurred irrespective of PD-L1 expression or microsatellite instability status and appeared to correlate with high tumor TGFB1 levels. CONCLUSIONS: In this first evaluation in Asian patients with heavily pretreated advanced GC/GEJC, bintrafusp alfa demonstrated a manageable safety profile and clinical activity.

First-in-Human Phase I Study of Aprutumab Ixadotin, a Fibroblast Growth Factor Receptor 2 Antibody-Drug Conjugate (BAY 1187982) in Patients with Advanced Cancer.

BACKGROUND: Fibroblast growth factor receptor (FGFR) 2 is overexpressed in several tumor types, including triple-negative breast cancer and gastric cancer, both of which have a high unmet medical need. Aprutumab ixadotin (BAY 1187982) is the first antibody-drug conjugate (ADC) to target FGFR2 and the first to use a novel auristatin-based payload. OBJECTIVE: This first-in-human trial was conducted to determine the safety, tolerability, and maximum tolerated dose (MTD) of aprutumab ixadotin in patients with advanced solid tumors from cancer indications known to be FGFR2-positive. PATIENTS AND METHODS: In this open-label, multicenter, phase I dose-escalation trial (NCT02368951), patients with advanced solid tumors received escalating doses of aprutumab ixadotin (starting at 0.1 mg/kg body weight), administered intravenously on day 1 of every 21-day cycle. Primary endpoints included safety, tolerability, and the MTD of aprutumab ixadotin; secondary endpoints were pharmacokinetic evaluation and tumor response to aprutumab ixadotin. RESULTS: Twenty patients received aprutumab ixadotin across five cohorts, at doses of 0.1-1.3 mg/kg. The most common grade ≥ 3 drug-related adverse events were anemia, aspartate aminotransferase increase, proteinuria, and thrombocytopenia. Dose-limiting toxicities were thrombocytopenia, proteinuria, and corneal epithelial microcysts, and were only seen in the two highest dosing cohorts. The MTD was determined to be 0.2 mg/kg due to lack of quantitative data following discontinuations at 0.4 and 0.8 mg/kg doses. One patient had stable disease; no responses were reported. CONCLUSIONS: Aprutumab ixadotin was poorly tolerated, with an MTD found to be below the therapeutic threshold estimated preclinically; therefore, the trial was terminated early. CLINICALTRIALS. GOV IDENTIFIER: NCT02368951.

A Phase I study of intravenous PI3K inhibitor copanlisib in Japanese patients with advanced or refractory solid tumors.

PURPOSE: To evaluate the safety, tolerability, pharmacokinetics, and efficacy of the intravenously administered pan-PI3K inhibitor copanlisib in Japanese patients with advanced or refractory solid tumors. METHODS: A Phase I open-label study in Japanese patients with advanced or refractory solid tumors was carried out. Patients received a single intravenous dose of either copanlisib 0.4 mg/kg or copanlisib 0.8 mg/kg, dosed intermittently on days 1, 8, and 15 of a 28-day cycle. Safety was monitored throughout the study. Plasma copanlisib levels were measured for pharmacokinetic analysis. RESULTS: Ten patients were enrolled and treated; three received copanlisib 0.4 mg/kg and seven received copanlisib 0.8 mg/kg. Overall, median duration of treatment was 6.2 weeks. No patients treated at 0.4 mg/kg experienced a dose-limiting toxicity, and the maximum tolerated dose in Japanese patients was determined to be 0.8 mg/kg. Adverse events were recorded in all ten patients; the most common were hyperglycemia, hypertension, and constipation. Copanlisib pharmacokinetic exposures displayed near dose-proportionality, with no accumulation. No patients achieved a complete or partial response, and disease control rate was 40.0%. CONCLUSIONS: Copanlisib was well tolerated in Japanese patients with advanced or refractory solid tumors, and the maximum tolerated dose was determined to be 0.8 mg/kg. Copanlisib demonstrated near dose-proportional pharmacokinetics and preliminary disease control, warranting further investigation. CLINICAL TRIAL REGISTRATION NUMBER: NCT01404390.

The role of PGP9.5 as a tumor suppressor gene in human cancer.

PGP9.5 is a controversial molecule from an oncologic point of view. We recently identified frequent methylation of PGP9.5 gene exclusively in primary head and neck squamous cell carcinoma (HNSCC), suggesting that it could be a tumor suppressor gene. On the other hand, PGP9.5 was reported to be overexpressed in a subset of human cancers presumably due to intrinsic oncogenic properties or as a result of transformation. To demonstrate that PGP9.5 possesses tumor suppressive activity, we examined forced expression by stable transfection of PGP9.5 in 4 HNSCC cell lines. Although all 4 cell lines demonstrated reduced log growth rates in culture after transfection, only 2 cell lines with wild type p53 (011, 022) demonstrated decreased growth in soft agar. In 2 cell lines with mutant p53 (013, 019), we observed no altered growth in soft agar and increased sensitivity to UV irradiation. We then tested for and found a high frequency of promoter methylation in a larger panel of primary tumors including HNSCC, esophageal SCC, gastric, lung, prostate and hepatocellular carcinoma. Our data support the notion that PGP9.5 is a tumor suppressor gene that is inactivated by promoter methylation or gene deletion in several types of human cancers.

HOP/OB1/NECC1 promoter DNA is frequently hypermethylated and involved in tumorigenic ability in esophageal squamous cell carcinoma.

Promoter DNA hypermethylation with gene silencing is a common feature of human cancer, and cancer-prone methylation is believed to be a landmark of tumor suppressor genes (TSG). Identification of novel methylated genes would not only aid in the development of tumor markers but also elucidate the biological behavior of human cancers. We identified several epigenetically silenced candidate TSGs by pharmacologic unmasking of esophageal squamous cell carcinoma (ESCC) cell lines by demethylating agents (5-aza-2'-deoxycitidine and trichostatin A) combined with ESCC expression profiles using expression microarray. HOP/OB1/NECC1 was identified as an epigenetically silenced candidate TSG and further examined for (a) expression status, (b) methylation status, and (c) functional involvement in cancer cell lines. (a) The HOP gene encodes two putative promoters (promoters A and B) associated with two open reading frames (HOPalpha and HOPbeta, respectively), and HOPalpha and HOPbeta were both down-regulated in ESCC independently. (b) Promoter B harbors dense CpG islands, in which we found dense methylation in a cancer-prone manner (55% in tumor tissues by TaqMan methylation-specific PCR), whereas promoter A does not harbor CpG islands. HOPbeta silencing was associated with DNA methylation of promoter B in nine ESCC cell lines tested, and reactivated by optimal conditions of demethylating agents, whereas HOPalpha silencing was not reactivated by such treatments. Forced expression of HOP suppressed tumorigenesis in soft agar in four different squamous cell carcinoma cell lines. More convincingly, RNA interference knockdown of HOP in TE2 cells showed drastic restoration of the oncogenic phenotype. In conclusion, HOP is a putative TSG that harbors tumor inhibitory activity, and we for the first time showed that the final shutdown process of HOP expression is linked to promoter DNA hypermethylation under the double control of the discrete promoter regions in cancer.

DCC promoter hypermethylation in esophageal squamous cell carcinoma.

Deleted in Colorectal Cancer (DCC) is a putative tumor suppressor gene, whose loss has been implicated in colorectal tumorigenesis. Decreased or loss of DCC expression has been demonstrated in a number of human cancers, including esophageal cancer. In this study, we analyzed esophageal squamous cell carcinoma (ESCC) cell lines and primary ESCCs as well as normal esophageal tissues for DCC methylation by bisulfite sequencing, methylation-specific PCR (MSP) and/or quantitative methylation-specific PCR (qMSP). When a qMSP cut-off value for positivity was set to 1.0, DCC methylation was detected in 10 of 12 ESCC cell lines tested, 74% of primary ESCCs (n = 70), 0% of corresponding normal esophageal tissues (n = 20) and 0% of normal esophagus from healthy individuals (n = 19). DCC expression was undetectable in the majority of ESCC cell lines, and treatment with the DNA methyltransferase inhibitor 5-aza-2'-deoxycytidine reactivated gene expression. DCC overexpression suppressed colony formation in ESCC cell lines, suggesting that DCC may function as a tumor suppressor gene in the esophagus. However, DCC methylation was not associated with any clinical or pathologic parameters measured. We have demonstrated that DCC methylation is a frequent and cancer-specific event in primary ESCCs, suggesting that DCC and associated pathways may represent a new diagnostical therapeutic target.

A promoter methylation pattern in the N-methyl-D-aspartate receptor 2B gene predicts poor prognosis in esophageal squamous cell carcinoma.

PURPOSE: To investigate whether the promoter methylation pattern in N-methyl-d-aspartate receptor 2B (NMDAR2B) is correlated with clinical features of human esophageal squamous cell carcinoma (ESCC), the methylation status of the gene was examined at three different sites (P1, P2, and P3) where two CpG islands reside within 1 kb upstream of the transcription start site. EXPERIMENTAL DESIGN: Three independent modalities for methylation analysis (bisulfite sequencing, combined bisulfite restriction analysis, and TaqMan methylation-specific PCR) were done to analyze total 67 ESCC tissues that included 43 primary tumors with well-characterized clinicopathologic variables including patient outcome. RESULTS: Using an optimized cutoff value based on quantitative methylation-specific PCR, we found that patients with higher NMDAR2B methylation ratio in the proximal region (P1) showed a worse 5-year disease-specific survival rate than those without NMDAR2B methylation (P < 0.006). A significant correlation was also seen between NMDAR2B promoter methylation and the presence of vascular permeation (P = 0.03). CONCLUSION: NMDAR2B promoter methylation could be a clinically applicable marker in ESCC.

p63 transcriptional regulation of epithelial integrity and cancer.

p63 plays a more complex role than initially thought in cancer and development. As a p53 homolog, p63 encodes transcription factors that primarily functions through regulation of downstream gene expression. However, p63 is also involved in RNA processing and activation of beta-catenin signaling. A number of genes activated by TAp63 support the notion that p63 is involved in tight transcriptional control of epithelial differentiation, cell adhesion, and tumorigenesis via cell cycle arrest, apoptosis, and other cellualr functions. In addition, DeltaNp63 isotypes retain a rather short transactivation domain and were found to transcriptionally regulate a specific set of downstream gene targets. We found that p63 is capable of activating gene expression through binding to specific cis-elements, RE1 and RE2, with the latter being more specific for p63 than for p53. Differences in p53 family members DNA binding may help to explain key differences in their function and biology.

A p53-type response element in the GDF15 promoter confers high specificity for p53 activation.

GDF15 is a transcriptional target gene for p53 and its family members, p63 and p73. Its promoter region contains two p53-type response elements, RE1 and RE2, and RE2 confers p53-specific transactivation. RE2 contains several mismatches from the canonical p53 response element (RRRCWWGYYY). Two mismatches in the RRR span and T base of the RE2 core sequence in the most 3' quarter-site are critical for inhibiting the binding affinity to p63 and p73 and corresponding promoter activity. Our results strongly suggest that differential DNA-binding affinities between p53 family member proteins act, at least in part, to confer specific target gene activation.

Overexpression of glycosylphosphatidylinositol (GPI) transamidase subunits phosphatidylinositol glycan class T and/or GPI anchor attachment 1 induces tumorigenesis and contributes to invasion in human breast cancer.

Based on the oncogenic role of phosphatidylinositol glycan (PIG) class U in human tumors, we explored the role of two additional subunits of the glycosylphosphatidylinositol (GPI) transamidase complex in human breast cancer. We found that PIG class T (PIG-T) and GPI anchor attachment 1 (GPAA1) were overexpressed in breast cancer cell lines and primary tumors. Forced expression of PIG-T and GPAA1 transformed NIH3T3 cells in vitro and increased tumorigenicity and invasion of these cells in vivo. Suppression of PIG-T expression in breast cancer cell lines led to inhibition of anchorage-independent growth. Moreover, we found that PIG-T and GPAA1 expression levels positively correlated with paxillin phosphorylation in invasive breast cancer cell lines. Furthermore, suppression of PIG-T and GPAA1 expression led to a decrease in paxillin phosphorylation with a concomitant decrease in invasion ability. These results suggest that the GPI transamidase complex is composed of a group of proto-oncogenes that individually or as a group contribute to breast cancer growth. This aberrant growth is mediated, at least partially, by phosphorylation of paxillin, contributing to invasion and progression of breast cancer.

N-methyl-D-aspartate receptor type 2B is epigenetically inactivated and exhibits tumor-suppressive activity in human esophageal cancer.

Promoter hypermethylation accompanied by gene silencing is a common feature of human cancers. We identified previously several new tumor suppressor genes based on pharmacologic unmasking of the promoter region and detection of reexpression on microarray analysis. In this study, we modified the selection of candidates from our previous microarray data by excluding genes that showed basal expression in cancer cell lines. With the new method, we found novel methylated genes with 90% accuracy. Among these 33 novel methylated genes that we identified in esophageal squamous cell carcinoma (ESCC) cell lines, N-methyl-D-aspartate receptor type 2B (NMDAR2B) was of particular interest. NMDAR2B was methylated in 95% of primary human ESCC tissue specimens and 12 ESCC cell lines by sequence analysis. NMDAR2B expression was silenced in all 12 ESCC cell lines and was reactivated by the demethylating agent 5-aza-2'-deoxycytidine. Moreover, reintroduction of the gene was accompanied by marked Ca(2+)-independent apoptosis in ESCC cell lines, suggesting that NMDAR2B can suppress tumor growth. Thus, NMDAR2B promoter methylation is common in ESCC, abrogating gene transcription and leading to cellular resistance to apoptosis.

PGP9.5 methylation in diffuse-type gastric cancer.

Diffuse-type gastric cancer (DGC) is the most deadly form of gastric cancer and is frequently accompanied by peritoneal dissemination and metastasis. The specific molecular events involved in DGC pathogenesis remain elusive. Accumulating evidence of epigenetic inactivation in tumor suppressor genes led us to conduct a comprehensive screen to identify novel methylated genes in human cancers using pharmacologic unmasking and subsequent microarray analysis. We compared differential RNA expression profiles of DGC and intestinal-type gastric cancer (IGC) cell lines treated with 5-aza-2'-deoxycytidine using microarrays containing 22,284 genes. We identified 16 methylated genes, including many novel genes, in DGC cell lines and studied PGP9.5 with particular interest. In primary gastric cancers, PGP9.5 was found to be more frequently methylated in DGCs (78%) than in IGCs (36%; DGC versus IGC, P < 0.05). Furthermore, real-time methylation-specific PCR analysis of PGP9.5 showed relatively higher methylation levels in DGC than in IGC. Our data thus implicate a molecular event common in the DGC phenotype compared with IGC.

A novel response element confers p63- and p73-specific activation of the WNT4 promoter.

The p53 tumor suppressor gene family consists of three genes, p53, p63, and p73. p53 family proteins share high homology in their DNA-binding domains but exhibit diverse biological functions. In this study, we demonstrated differential target gene activation by specific p53, p63, and p73 induction in Saos2 cells by oligonucleotide microarray expression analysis. We further analyzed the WNT4 promoter, which was induced by p63 and p73 but not p53, in order to clarify the mechanism of differential target gene activation between the three family members. Luciferase analysis showed that the WNT4 promoter harbors two p63/p73 response elements, designated RE1 and RE2. RE1 resembles the canonical p53 response element (tandem repeats of RRRCWWGYYY), located between -141 and -121, while RE2 consists of a GC-rich sequence further downstream. Neither response element alone was able to confer transcriptional activity. It is thus likely that both RE1 and RE2 are necessary in rendering p63/p73-specific activation of the WNT4 promoter.

The effect of p53-RNAi and p53 knockout on human 8-oxoguanine DNA glycosylase (hOgg1) activity.

Recent evidence indicates that in vitro p53 augments base excision repair (BER) activities in mammalian cells. To understand the role of p53 in BER, we analyzed the repair activity of hOgg1 in isogenic cell lines HCT116p53+/+ and HCT116p53-/-. We found that hOgg1 activity was significantly decreased in HCT116p53-/- cells as compared with HCT116p53+/+ cells, indicating a functional role for p53 in the regulation of hOGG1. Using gel-shift assays, we showed that p53 binds to its putative cis-elements within the hOGG1 promoter. In addition we demonstrated that supplementing p53 in HCT116p53-/- cells enhanced the transcription of hOGG1. To further strengthen our findings, we used p53-RNAi to study the effects of decreased p53 levels on hOgg1 activity. We observed that p53-RNAi resulted in decreased hOGG1 expression both at the mRNA and protein levels. This decrease in hOGG1 expression was associated with reduced cell viability upon oxidative damage and reduced hOgg1 activity as evidenced by the 8-oxoG incision assay. Taken together, our results indicate that loss of p53 function can lead to decreased hOgg1 repair activity.

[CPT-11-induced diarrhea treated with indisetron hydrochloride--a case report].

We report a case in which 5-HT3 receptor antagonist, indisetron hydrochloride,was effective against CPT-11-induced diarrhea. When the patient, a 63-year-old male, developed lymph node metastases after resection for primary gastric cancer, 24-hour continuous administration of CPT-11 (125 mg/m2) was initiated. The following day he had diarrhea, possibly associated with the CPT-11. Hange-shashinto was administered but did not improve the condition. Thereafter, the diarrhea followed a protracted course (grade 1 to 2). His diarrhea improved when indisetron hydrochloride was administered with the fifth course of chemotherapy in place of the usual antiemetic drug. In this patient, indisetron hydrochloride, in addition to its role as an antiemetic, was considered to be effective against CPT-11-induced diarrhea.

Differential recognition of response elements determines target gene specificity for p53 and p63.

p63 is a member of the p53 tumor suppressor gene family, which regulates downstream target gene expression by binding to sequence-specific response elements similar to those of p53. By using oligonucleotide expression microarray analysis and analyzing the promoters of p63-induced genes, we have identified novel p63-specific response elements (p63-REs) in the promoter regions of EVPL and SMARCD3. These p63-REs exhibit characteristic differences from the canonical p53-RE (RRRCWWGYYY) in both the core-binding element (CWWG) as well as the RRR and/or YYY stretches. Luciferase assays on mutagenized promoter constructs followed by electromobility shift analysis showed that p53 preferentially activates and binds to the RRRCATGYYY sequence, whereas p63 preferentially activates RRRCGTGYYY. Whereas EVPL protein is highly expressed in epithelial cells of the skin and pharynx in the p63+/+ mouse, it is undetectable in these tissues in the p63-/- mouse. Our results indicate that p63 can regulate expression of specific target genes such as those involved in skin, limb, and craniofacial development by preferentially activating distinct p63-specific response elements.