A Phase 2 Study of Galunisertib (TGF-ß1 Receptor Type I Inhibitor) and Sorafenib in Patients With Advanced Hepatocellular Carcinoma.

INTRODUCTION: Inhibition of tumor growth factor-ß (TGF-ß) receptor type I potentiated the activity of sorafenib in preclinical models of hepatocellular carcinoma (HCC). Galunisertib is a small-molecule selective inhibitor of TGF-ß1 receptor type I, which demonstrated activity in a phase 2 trial as second-line HCC treatment. METHODS: The combination of galunisertib and sorafenib (400 mg BID) was tested in patients with advanced HCC and Child-Pugh A liver function without prior systemic therapy. Galunisertib dose was administered 80 or 150 mg b.i.d. orally for 14 days every 28 days in safety lead-in cohorts; in the expansion cohort, all patients received galunisertib 150 mg b.i.d. Objectives included time-to-tumor progression, changes in circulating alpha fetoprotein and TGF-ß1, safety, overall survival (OS), response rate, and pharmacokinetics (PK). RESULTS: Patients (n = 47) were enrolled from 5 non-Asian countries; 3 and 44 patients received the 80 mg and 150 mg b.i.d. doses of galunisertib, respectively. The pharmacokinetics and safety profiles were consistent with monotherapy of each drug. For the 150 mg b.i.d. galunisertib cohort, the median time-to-tumor progression was 4.1 months; the median OS was 18.8 months. A partial response was seen in 2 patients, stable disease in 21, and progressive disease in 13. TGF-ß1 responders (decrease of >20% from baseline) vs nonresponders had longer OS (22.8 vs 12.0 months, P = 0.038). DISCUSSION: The combination of galunisertib and sorafenib showed acceptable safety and a prolonged OS outcome.

Development and validation of a phosphorylated SMAD ex vivo stimulation assay.

Assessing the pharmacodynamics (PD) of a potential therapeutic through the use of a downstream biomarker is essential. This is traditionally performed in the target tissue but limited volume and invasiveness of sampling pose challenges with solid tumours. Currently, there are several small molecule receptor kinase inhibitors and large molecule therapeutic antibodies in clinical trials that interfere with TGFbeta signalling to treat various forms of cancer. With the advent of these new therapies, there is a need for a surrogate tissue that is easily accessible and indicative of tumour response. We propose the use of an ex vivo TGFbeta1 stimulation of peripheral blood mononuclear cells (PBMCs) coupled with the measurement of phosphorylated SMAD2 (Sma/Mothers Against dpp, a downstream transcriptional activator) using a sandwich ELISA. TGFbeta is involved in many different cellular responses, such as proliferation, angiogenesis, migration, invasion and immunomodulation. SMAD2 and SMAD3 are phosphorylated as a result of the canonical cascade through ligand binding and receptor kinase activation. These phosphorylated SMADs (pSMAD) associate with SMAD4, a co-SMAD, and transcriptionally activate TGFbeta-mediated genes. This paper describes the novel method for measuring the downstream effects of inhibiting canonical TGFbeta signalling using ex vivo stimulation of surrogate tissue to predict tumour response. In addition, we present the assay validation rationale and data. This novel, validated assay can be used to gain insight into clinical trials regarding TGFbeta signal modulation by multiple inhibitor platforms for both large and small molecules.