Serum iron element: A novel biomarker for predicting PD-1 immunotherapy efficacy

This study aims to explore the relationship between serum iron by inductively coupled plasma-mass spectrometry (ICP-MS) and the efficacy of immune checkpoint inhibitors (ICIs) and potential mechanism. Totally 113 patients from 233 patients with advanced metastatic lung cancer, esophageal cancer, gastric cancer and colorectal cancer who treated with immunotherapy in Shandong Provincial Hospital were divided into training group (n=68) and validation group (n=45), whose patients were divided into clinical benefit response (CBR) and non-clinical benefit (NCB) by RECIST (v1.1) respectively. We found for the first time that high serum iron level (>1036 μg/L) was a novel biomarker of better PFS (10.13 months vs 7.37 months; p = 0.0015) and OS(16.00 months vs 11.00 months; p = 0.0235) by ROC curve (sensitivity: 78.13 %; Specificity: 80.56 %; p < 0.0001) of CBR (n=32) and NCB (n=36) patients in training group. Interestingly, consistently stable and high serum iron level predicted better efficacy during immunotherapy. Noteworthy, the predictive efficacy of PD-L1 expression was significantly inferior than serum iron (accuracy:63.49% vs 79.41%, p=0.0432), while serum iron detected by spectrophotometry did not predict the efficacy of immunotherapy (p=0.0671) indicating higher sensitivity of ICP-MS. Bioinformatics analysis showed that serum iron could enhance innate immunity and cytokine release and was verified by proteomics that KEGG and GO analysis enriched innate immune and cytokine signaling pathways. Flow cytometry showed that IL-17 (p=0.0002) increased and IL-6 (p=0.0112) decreased after immunotherapy. Based on this, Nomogram with better prediction was constructed by multiple clinical and independent factors. Our results revealed that serum iron is positively associated with ICIs efficacy by enhancing innate immunity and cytokine release in advanced metastatic cancers, and can be a biomarker for predicting ICIs response.

Safety, PK/PD and preliminary anti-tumor activities of pegylated recombinant human arginase 1 (BCT-100) in patients with advanced arginine auxotrophic tumors

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.