Two first-in-human studies of xentuzumab, a humanised insulin-like growth factor (IGF)-neutralising antibody, in patients with advanced solid tumours

BACKGROUND: Xentuzumab, an insulin-like growth factor (IGF)-1/IGF-2-neutralising antibody, binds IGF-1 and IGF-2, inhibiting their growth-promoting signalling. Two first-in-human trials assessed the maximum-tolerated/relevant biological dose (MTD/RBD), safety, pharmacokinetics, pharmacodynamics, and activity of xentuzumab in advanced/metastatic solid cancers. METHODS: These phase 1, open-label trials comprised dose-finding (part I; 3 + 3 design) and expansion cohorts (part II; selected tumours; RBD [weekly dosing]). Primary endpoints were MTD/RBD. RESULTS: Study 1280.1 involved 61 patients (part I: xentuzumab 10–1800 mg weekly, n = 48; part II: 1000 mg weekly, n = 13); study 1280.2, 64 patients (part I: 10–3600 mg three-weekly, n = 33; part II: 1000 mg weekly, n = 31). One dose-limiting toxicity occurred; the MTD was not reached for either schedule. Adverse events were generally grade 1/2, mostly gastrointestinal. Xentuzumab showed dose-proportional pharmacokinetics. Total plasma IGF-1 increased dose dependently, plateauing at ~1000 mg/week; at ≥450 mg/week, IGF bioactivity was almost undetectable. Two partial responses occurred (poorly differentiated nasopharyngeal carcinoma and peripheral primitive neuroectodermal tumour). Integration of biomarker and response data by Bayesian Logistic Regression Modeling (BLRM) confirmed the RBD. CONCLUSIONS: Xentuzumab was well tolerated; MTD was not reached. RBD was 1000 mg weekly, confirmed by BLRM. Xentuzumab showed preliminary anti-tumour activity

Alpha-fetoprotein as a potential surrogate biomarker for atezolizumab + bevacizumab treatment of hepatocellular carcinoma

Purpose: Atezolizumab + bevacizumab is the new standard of care for systemic treatment-naïve, unresectable hepatocellular carcinoma (HCC). This exploratory study investigated on-treatment alpha-fetoprotein (AFP) response as a potential surrogate biomarker of prognosis for the combination therapy. Experimental design: Data from Group A of the phase Ib GO30140 study were used to identify the optimal time for AFP measurement and AFP cutoffs to differentiate patients by their best confirmed response per independent review facility-assessed RECIST (IRF-RECIST) version 1.1: responders from nonresponders and patients with disease control from primary progressors. We applied these cutoffs to independent data from the atezolizumab + bevacizumab arm of the phase III IMbrave150 trial to distinguish patients based on (i) overall survival (OS) and progression-free survival (PFS) per IRF-RECIST 1.1 and (ii) best confirmed response per IRF-RECIST 1.1. Results: We derived AFP cutoffs of ≥75% decrease and ≤10% increase from baseline at 6 weeks to identify responders and those who had disease control, respectively. These cutoffs had high sensitivity and specificity in GO30140. In IMbrave150 patients, sensitivity was 0.59 and specificity was 0.86 for the ≥75% decrease AFP cutoff; the sensitivity was 0.77 and specificity was 0.44 for the ≤10% increase AFP cutoff. Both AFP cutoffs were associated with longer OS and PFS, particularly in patients with hepatitis B virus etiology (HR < 0.5; P < 0.01). Conclusions: AFP response at 6 weeks after initiating treatment is a potential surrogate biomarker of prognosis for patients with HCC receiving atezolizumab + bevacizumab. See related commentary by Cappuyns and Llovet, p. 3405

Two first-in-human studies of xentuzumab, a humanised insulin-like growth factor (IGF)-neutralising antibody, in patients with advanced solid tumours

BACKGROUND: Xentuzumab, an insulin-like growth factor (IGF)-1/IGF-2-neutralising antibody, binds IGF-1 and IGF-2, inhibiting their growth-promoting signalling. Two first-in-human trials assessed the maximum-tolerated/relevant biological dose (MTD/RBD), safety, pharmacokinetics, pharmacodynamics, and activity of xentuzumab in advanced/metastatic solid cancers. METHODS: These phase 1, open-label trials comprised dose-finding (part I; 3 + 3 design) and expansion cohorts (part II; selected tumours; RBD [weekly dosing]). Primary endpoints were MTD/RBD. RESULTS: Study 1280.1 involved 61 patients (part I: xentuzumab 10–1800 mg weekly, n = 48; part II: 1000 mg weekly, n = 13); study 1280.2, 64 patients (part I: 10–3600 mg three-weekly, n = 33; part II: 1000 mg weekly, n = 31). One dose-limiting toxicity occurred; the MTD was not reached for either schedule. Adverse events were generally grade 1/2, mostly gastrointestinal. Xentuzumab showed dose-proportional pharmacokinetics. Total plasma IGF-1 increased dose dependently, plateauing at ~1000 mg/week; at ≥450 mg/week, IGF bioactivity was almost undetectable. Two partial responses occurred (poorly differentiated nasopharyngeal carcinoma and peripheral primitive neuroectodermal tumour). Integration of biomarker and response data by Bayesian Logistic Regression Modeling (BLRM) confirmed the RBD. CONCLUSIONS: Xentuzumab was well tolerated; MTD was not reached. RBD was 1000 mg weekly, confirmed by BLRM. Xentuzumab showed preliminary anti-tumour activity