Novel therapeutic targets and predictive markers for hepatocellular carcinoma

Personalized treatment for hepatocellular carcinoma: Current status and future perspectives

Systemic treatment for hepatocellular carcinoma (HCC) has been advancing rapidly over the last decade. More novel agents, including both targeted agents and immune checkpoint inhibitors, are available for physicians to use sequentially or concurrently for patients with advanced HCC. Despite more options, only a proportion of patients benefit from each regimen. Therefore, clinicians are facing challenges on how to choose the right regimen for the right patient with HCC, which raises the importance of personalized treatment approach. To advance personalized treatment for HCC, one approach relies on the acquisition of biomarker data from clinical trials to evaluate clinical parameters or genotypes in association with outcomes of selected drugs. This approach has led to finding of high baseline alpha-fetoprotein levels in association with benefits of ramucirumab. Cumulative findings from multiple clinical trials and translational studies also suggest that selected etiology and/or genotype of HCC could predict resistance to immune checkpoint inhibitors. The second approach is to decipher the tumor heterogeneity of HCC with an aim to identify clinically relevant patterns to guide clinical decisions. Tumor heterogeneity could exist within a single tumor (intra-tumoral heterogeneity), among different tumors in the same patient (inter-tumoral heterogeneity) or between primary and recurrent tumors (temporal tumor heterogeneity). The analyses of tumor heterogeneity have also been powered by coverage of tumor immune environment and incorporation of circulating tumor nucleic acid technology. Emerging publications have been reported above tumor heterogeneity exist in HCC, which is potentially clinically impactful.

A phase II clinical study on the efficacy and predictive biomarker of pegylated recombinant arginase on hepatocellular carcinoma

Background: Pegylated recombinant human arginase (PEG-BCT-100) is an arginine depleting drug. Preclinical studies showed that HCC is reliant on exogenous arginine for growth due to the under-expression of the arginine regenerating enzymes argininosuccinate synthetase (ASS) and ornithine transcarbamylase (OTC). Methods: This is a single arm open-label Phase II trial to assess the potential clinical efficacy of PEG-BCT-100 in chemo naïve sorafenib-failure HCC patients. Pre-treatment tumour biopsy was mandated for ASS and OTC expression by immunohistochemistry (IHC). Weekly intravenous PEG-BCT-100 at 2.7 mg/kg was given. Primary endpoint was time to progression (TTP); secondary endpoints included radiological response as per RECIST1.1, progression free survival (PFS) and overall survival (OS). Treatment outcomes were correlated with tumour immunohistochemical expressions of ASS and OTC. Results: In total 27 patients were recruited. The median TTP and PFS were both 6 weeks (95% CI, 5.9–6.0 weeks). The disease control rate (DCR) was 21.7% (5 stable disease). The drug was well tolerated. Post hoc analysis showed that duration of arginine depletion correlated with OS. For patients with available IHC results, 10 patients with ASS-negative tumour had OS of 35 weeks (95% CI: 8.3–78.0 weeks) vs. 15.14 weeks (95% CI: 13.4–15.1 weeks) in 3 with ASS-positive tumour; expression of OTC did not correlate with treatment outcomes. Conclusions: PEG-BCT-100 in chemo naïve post-sorafenib HCC is well tolerated with moderate DCR. ASS-negative confers OS advantage over ASS-positive HCC. ASS-negativity is a potential biomarker for OS in HCC and possibly for other ASS-negative arginine auxotrophic cancers. Trial registration number: NCT01092091. Date of registration: March 23, 2010.

Imaging the expression of glypican-3 in hepatocellular carcinoma by PET

The glypican-3 (GPC3) receptor is overexpressed in hepatocellular carcinoma (HCC) and is a potential diagnostic and therapeutic target. GPC3-targeted molecular imaging will be helpful to differentiate diagnosis and guide therapy. In the present study, we will develop a novel PET probe for imaging the expression of GPC-3. L5 (sequence: RLNVGGTYFLTTRQ), a GPC3 targeting peptide, was labeled with 5-carboxyfluorescein (FAM) and ¹⁸F-fluoride. Cell binding tests were performed to identify the binding specificity of FAM-L5 and ¹⁸F radiolabeled peptide. MicroPET/CT imaging was used to determine the potential of a novel PET tracer for visualizing HCC tumors with a high expression of GPC3. In vitro binding tests showed that the uptake of FAM-L5 in HepG2 cells (high expression of GPC3) was significantly higher than that of HL-7702 cells (negative expression of GPC3) (mean fluorescent intensity: 14,094 ± 797 vs. 2765 ± 314 events, t = 32.363, P = 0.000). Confocal fluorescent imaging identified that FAM-L5 accumulated where the GPC3 receptor was located. A novel PET tracer (¹⁸F-AlF-NODA-MP-6-Aoc-L5) was successfully labeled by chelation chemistry. In vitro cell uptake studies showed that ¹⁸F-AlF-NODA-MP-6-Aoc-L5 can bind to HepG2 tumor cells and was stable in PBS and mouse serum stability tests. MicroPET/CT showed that HepG2 tumors could be clearly visualized with a tumor/muscle ratio of 2.46 ± 0.53. However, the tumor/liver ratio was low (0.93 ± 0.16) due to the high physiological uptake in the liver. This study demonstrates that FAM and the ¹⁸F-labeled L5 peptide can selectively target HCC with a high expression of GPC3 in vitro and in vivo. ¹⁸F-AlF-NODA-MP-C6-L5 has the potential to be a GPC3 target tracer but requires some chemical modifications to achieve a high enough tumor/liver ratio for detection of the tumor in the liver.

The application of antitumor drug-targeting models on liver cancer

Hepatocarcinoma animal models, such as the induced tumor model, transplanted tumor model, gene animal model, are significant experimental tools for the evaluation of targeting drug delivery system as well as the pre-clinical studies of liver cancer. The application of antitumor drug-targeting models not only furnishes similar biological characteristics to human liver cancer but also offers guarantee of pharmacokinetic indicators of the liver-targeting preparations. In this article, we have reviewed some kinds of antitumor drug-targeting models of hepatoma and speculated that the research on this field would be capable of attaining a deeper level and expecting a superior achievement in the future.