Bio-Cancer Treatment International Limited.

To fuel accelerated proliferation, leukaemic cells undergo metabolic deregulation, which can result in specific nutrient dependencies. Here, we perform an amino acid drop‐out screen and apply pre‐clinical models of chronic phase chronic myeloid leukaemia (CML) to identify arginine as a nutrient essential for primary human CML cells. Analysis of the Microarray Innovations in Leukaemia (MILE) dataset uncovers reduced ASS1 levels in CML compared to most other leukaemia types. Stable isotope tracing reveals repressed activity of all urea cycle enzymes in patient‐derived CML CD34+ cells, rendering them arginine auxotrophic. Thus, arginine deprivation completely blocks proliferation of CML CD34+ cells and induces significantly higher levels of apoptosis when compared to arginine‐deprived cell lines. Similarly, primary CML cells, but not normal CD34+ samples, are particularly sensitive to treatment with the arginine‐depleting enzyme, BCT‐100, which induces apoptosis and reduces clonogenicity. Moreover, BCT‐100 is highly efficacious in a patient‐derived xenograft model, causing > 90% reduction in the number of human leukaemic stem cells (LSCs). These findings indicate arginine depletion to be a promising and novel strategy to eradicate therapy resistant LSCs.

We investigated the safety and efficacy of a pegylated arginase (PEG-BCT-100) in combination with chemotherapy (oxaliplatin and capecitabine) [PACOX] in advanced HCC patients.

This was a single centre phase 1 trial to assess the safety and tolerability of PACOX. All the enrolled subjects received treatment in 3-weekly cycles: intravenous PEG-BCT-100 2.7 mg/kg on days 1, 8 and 15 of each cycle; oral capecitabine 1000 mg/m² twice daily on day 1-14 of each cycle and intravenous oxaliplatin on day 1. Three dose levels of oxaliplatin (85 mg/m², 100 mg/m² or 130 mg/m²) were studied to define the maximum tolerated dose (MTD). Adverse events (AEs), efficacy by RECIST v1.1, time to progression (TTP), progression-free survival (PFS) and overall survival (OS) were studied.

Seventeen patients were enrolled at 3 dose levels of oxaliplatin: 85 mg/m² (8 patients), 100 mg/m² (3 patients), and 130 mg/m² (6 patients). The median age was 55 years; all had had locoregional chemotherapy or targeted therapy such as sorafenib, but no systemic chemotherapy. The most common AEs were nausea (82%), injection site reaction (76%), palmar-plantar erythrodysesthesia (59%), oral mucositis (53%) and vomiting (53%). There was no dose-limiting toxicity (DLT). Median duration on study was 8 weeks overall. In 14 evaluable cases, one achieved partial response (PR), 4 had stable disease (SD); disease control rate was 36%; most responses were observed in the 130 mg/m² cohort with 1 PR and 2 SDs. Median TTP and PFS were both 7.0 weeks. Overall median OS was 10.7 months; the median OS was not reached at 19.4 months of follow-up in the 130 mg/m2 cohort.

The PACOX regimen demonstrated good anti-cancer activity and survival advantage in advanced pre-treated HCC with favourable safety profile. It warrants further phase II/III studies.

Background The study determined the safety, pharmacokinetics/pharmacodynamics (PK/PD), and recommended Phase II dose of BCT-100 for arginine auxotrophic tumours in a non-Chinese population. Methods This is a Phase I, 3 + 3 dose-escalation, open-label, multi-centre study in two arginine auxotrophic cancers-Malignant Melanoma (MM) and Castration Resistant Prostate Cancer (CRPC). Patients were enrolled to receive weekly intravenous BCT-100. The dose cohorts were respectively 0.5 mg/kg, 1.0 mg/kg, 1.7 mg/kg and 2.7 mg/kg. Results There were 14 MM and 9 CRPC patients, 16 males and 7 females with a median age of 71. No dose-limiting toxicities were reported. Among all the AEs, 18 were drug-related (mostly were Grade 1). Although there were individual variations in PKs amongst the patients in each cohort, the median arginine level was maintained at 2.5 µM (lower limit of quantification) in all 4 cohorts of patients after the second BCT-100 injection. Therapeutic Arginine Depletion was found in the 1.7 and 2.7 mg/kg/week cohorts when anti-tumor activities were observed. The two cohorts had a similar AUC (20,947 and 19,614 h*µg/ml respectively). Since the 2.7 mg/kg/week cohort had a more sustained arginine depletion for 2 weeks, the 2.7 mg/kg/week dose is chosen as the future phase II dose. There were two complete remissions (1 MM & 1 CRPC), 1PR (MM) and 2 stable diseases with a disease control rate (CR + PR + SD) of 5/23 (22%). Conclusions BCT-100 is safe in a non-Chinese population and has anti-tumor activities in both MM and CRPC. Weekly BCT-100 at 2.7 mg/kg is defined as the optimal biological dose for future clinical phase II studies.