Apoptotic epithelial cells control the abundance of Treg cells at barrier surfaces.

Epithelial tissues continually undergo apoptosis. Commensal organisms that inhabit the epithelium influence tissue homeostasis, in which regulatory T cells (Treg cells) have a central role. However, the physiological importance of epithelial cell apoptosis and how the number of Treg cells is regulated are both incompletely understood. Here we found that apoptotic epithelial cells negatively regulated the commensal-stimulated proliferation of Treg cells. Gut commensals stimulated CX3CR1(+)CD103(-)CD11b(+) dendritic cells (DCs) to produce interferon-ß (IFN-ß), which augmented the proliferation of Treg cells in the intestine. Conversely, phosphatidylserine exposed on apoptotic epithelial cells suppressed IFN-ß production by the DCs via inhibitory signaling mediated by the cell-surface glycoprotein CD300a and thus suppressed Treg cell proliferation. Our findings reveal a regulatory role for apoptotic epithelial cells in maintaining the number of Treg cell and tissue homeostasis.

Phase I study of napabucasin in combination with FOLFIRI + bevacizumab in Japanese patients with metastatic colorectal cancer.

BACKGROUND: Napabucasin is an oral NAD(P)H:quinone oxidoreductase 1 bioactivatable agent that generates reactive oxygen species, is hypothesised to affect multiple oncogenic cellular pathways, including STAT-3, and is expected to result in cancer cell death. This phase I study investigated the safety, tolerability, and pharmacokinetics of napabucasin co-administered with fluorouracil, l-leucovorin, and irinotecan (FOLFIRI) chemotherapy plus bevacizumab in Japanese patients with metastatic colorectal cancer (CRC). METHODS: Patients with histologically confirmed unresectable stage IV CRC received oral napabucasin 240 mg twice daily (BID). Intravenous FOLFIRI and bevacizumab therapy was initiated on day 3 at approved doses. Unacceptable toxicity was evaluated over the first 30 days of treatment, after which treatment continued in 14-day cycles until toxicity or disease progression. Endpoints included safety, pharmacokinetics, and tumour response based on RECIST v1.1. RESULTS: Four patients received treatment; three were evaluable during the unacceptable toxicity period. All four patients experienced diarrhoea and decreased appetite (considered napabucasin-related in four and two patients, respectively), and three patients experienced neutrophil count decreased. No unacceptable toxicity was reported during the 30-day evaluation period. No grade 4 events, deaths, or serious adverse events were reported. The addition of FOLFIRI and bevacizumab to napabucasin did not significantly change the pharmacokinetic profile of napabucasin; however, results were variable among patients. The best overall response was stable disease in two patients (50.0%). CONCLUSIONS: Napabucasin 240 mg BID in combination with FOLFIRI and bevacizumab was tolerated, with a manageable safety profile in Japanese patients with metastatic CRC.

A Phase I Study to Investigate the Safety, Tolerability and Pharmacokinetics of Napabucasin Combined with Sorafenib in Japanese Patients with Unresectable Hepatocellular Carcinoma.

BACKGROUND AND OBJECTIVE: For patients with advanced hepatocellular carcinoma (HCC), the standard of care for many years has been sorafenib. Preliminary data have suggested that the combination of the NAD(P)H:quinone oxidoreductase 1 bioactivatable agent napabucasin plus sorafenib may improve clinical outcomes in patients with HCC. In this phase I, multicenter, uncontrolled, open-label study, we evaluated napabucasin (480 mg/day) plus sorafenib (800 mg/day) in Japanese patients with unresectable HCC. METHODS: Adults with unresectable HCC and an Eastern Cooperative Oncology Group performance status of 0 or 1 were enrolled in a 3 + 3 trial design. The occurrence of dose-limiting toxicities was assessed through 29 days from the start of napabucasin administration. Additional endpoints included safety, pharmacokinetics, and preliminary antitumor efficacy. RESULTS: In the six patients who initiated treatment with napabucasin, no dose-limiting toxicities occurred. The most frequently reported adverse events were diarrhea (83.3%) and palmar-plantar erythrodysesthesia syndrome (66.7%), all of which were grade 1 or 2. The pharmacokinetic results for napabucasin were consistent with prior publications. The best overall response (per Response Evaluation Criteria in Solid Tumors [RECIST] version 1.1) was stable disease in four patients. Using Kaplan-Meier methodology, the 6-month progression-free survival rate was 16.7% per RECIST 1.1 and 20.0% per modified RECIST for HCC. The 12-month overall survival rate was 50.0%. CONCLUSIONS: These findings confirm the viability of napabucasin plus sorafenib treatment, and there were no safety or tolerability concerns in Japanese patients with unresectable HCC. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov identifier NCT02358395, registered on 9 February 2015.

Effects of a reactive oxygen species generator, napabucasin (BBI608), on tolerability, safety, pharmacokinetics, and QT/QTc interval in healthy volunteers.

This study examined the safety, tolerability, and pharmacokinetics (PK) of napabucasin in healthy Asian and non-Asian participants and investigated the potential for QT/QTc interval prolongation. This five-part (A-E) study proceeded in a stepwise manner, unless stopping criteria were met. Parts A-D were randomized, double-blind, placebo-controlled, and included healthy Asian male and female and non-Asian male participants. PK parameters were measured following single-dose napabucasin (80-1200 mg) in the fasted or fed state (Part D). Potential QT/QTc interval prolongation was assessed using digital 12-lead electrocardiogram (Parts B and C). Part E was open-label, and examined the PK of single-dose napabucasin (240-720 mg) in healthy non-Asian males. Safety and tolerability were measured in Parts A-E. Changes from baseline in the Fridericia-corrected QT interval (ΔQTcF) and other electrocardiogram parameters were analyzed using a linear mixed-effects model. Napabucasin was well-tolerated across the study (n = 70), and no serious adverse events or significant safety issues were reported when administered with or without food. The most frequent treatment-emergent adverse events were diarrhea and abdominal pain, and these were mild in severity. No prolongation of the QTcF interval was reported following single-dose napabucasin (240-1200 mg) and changes in other cardiac parameters were negligible. The PK profile of napabucasin was consistent with earlier studies. Single-dose napabucasin was tolerated in healthy male and female participants, and no significant safety (including no QTcF prolongation) or tolerability issues were identified, irrespective of food intake. Clinical studies of napabucasin in advanced cancers are ongoing.

Phase 1 study of napabucasin, a cancer stemness inhibitor, in patients with advanced solid tumors.

PURPOSE: Napabucasin is a cancer stemness inhibitor that targets a number of oncogenic pathways, including signal transducer and activator of transcription 3 (STAT3). Phase 1/2 studies suggest tolerability and anti-tumor activity in various types of cancer; a Phase 3 study of napabucasin plus standard therapy in colorectal cancer is ongoing. This is a Phase 1 dose-escalation study in patients with advanced solid tumors, and the first study of napabucasin in Japanese patients. METHODS: Patients received napabucasin 480, 960, or 1440 mg daily in 28-day cycles until disease progression or intolerable toxicity. Primary objectives were to determine dose-limiting toxicities (DLTs), maximum tolerated dose (MTD), and the pharmacokinetic (PK) profile of napabucasin. Blood samples were taken for PK analysis on Days 1, 2, 8, and 15 of Cycle 1, and Days 29 and 30 of Cycle 2. Secondary objectives were to assess napabucasin antitumor activity, and the relationship between biomarkers and antitumor activity. JapicCTI-No: JapicCTI-132152. RESULTS: Enrolled were 14 patients (480 mg [n = 3], 960 mg [n = 4], 1440 mg [n = 7]). One patient experienced a DLT (Grade 3, anorexia). MTD was 1440 mg/day. Most common drug-related adverse events were diarrhea (n = 9), nausea (n = 4), vomiting (n = 3), and anorexia (n = 3). Napabucasin showed a similar PK profile to previous studies and no abnormal accumulation was observed. Following treatment, two patients had stable disease; the remaining 12 had progressive disease. CONCLUSION: Napabucasin was well-tolerated at doses up to 1440 mg/day in Japanese patients with advanced solid tumors; the PK profile was comparable to that reported previously.

A Phase I Study of Napabucasin Plus Paclitaxel for Japanese Patients With Advanced/Recurrent Gastric Cancer.

AIM: To report results from the first phase I study of napabucasin plus paclitaxel in Japanese patients with pre-treated unresectable/recurrent gastric cancer. PATIENTS AND METHODS: Patients received napabucasin (480 mg bid) plus paclitaxel [80 mg/m2 on days 3, 10 and 17 (cycles 1 and 2) and on days 1, 8 and 15 (cycle 3 and subsequent cycles)] until disease progression or unacceptable toxicity. Primary objectives were tolerability, safety and pharmacokinetics of napabucasin plus paclitaxel. Trial registration ID: JapicCTI-142420. RESULTS: Six patients were enrolled. Paclitaxel had a minimal effect on napabucasin pharmacokinetics and median plasma paclitaxel concentrations were similar in combination and monotherapy. No dose-limiting toxicities were observed. There were no grade 4/5 adverse events. Partial response, stable disease and progressive disease were reported in two patients each. CONCLUSION: Napabucasin plus paclitaxel was well-tolerated in Japanese patients with gastric cancer.