A number of novel therapies are currently being explored as second-line treatments for patients with advanced hepatocellular carcinoma, including a host of targeted therapies and various immune checkpoint inhibitors.
Ghassan Abou-Alfa, MD
A number of novel therapies are currently being explored as second-line treatments for patients with advanced hepatocellular carcinoma (HCC), including a host of targeted therapies and various immune checkpoint inhibitors, according to Ghassan Abou-Alfa, MD, at the 1st Annual School of Gastrointestinal Oncology.
“Almost 15 years ago, there was very little interest in the disease, now there is a plethora of clinical trials that are readily available in the first-, second-, and third-line setting,” explained Abou-Alfa, a medical oncologist at Memorial Sloan Kettering Cancer Center. “I highly encourage the physicians and their patients to seek clinical trials in those settings, because short of sorafenib there is nothing called 'standard of care.' There is diversity in regard to the targets, this is going to give a wealth of information.”
Sorafenib was approved based on the phase III SHARP trial,1 which randomized 602 patients to the multikinase inhibitor (n = 299) or placebo (n = 303). Median overall survival (OS) with sorafenib was 10.7 months compared with 7.9 months with placebo, representing the first and only systemic therapy to improve survival in a phase III study for patients with HCC. In the trial, there was a 31% reduction in the risk of death with sorafenib (HR, 0.69; 95% CI, 0.55-0.87; P <.001).
Following this demonstration of success, a number of studies were commenced in an attempt to build upon these results, including an investigation of adjuvant sorafenib for patients with HCC. Unfortunately, this study failed to show a benefit for sorafenib versus placebo.
In the trial,2 1114 patients were randomized to sorafenib (n = 556) or placebo (n = 558) following ablation or resection. At the final analysis, the median recurrence-free survival (RFS) was 33.3 months with sorafenib versus 33.7 months with placebo (HR, 0.94; 95% CI, 0.780-1.134; P =. 26). Median OS was not yet assessable from the study (HR, 0.995; 95% CI, 0.761-1.300; P = .48).
In a separate phase II study,3 sorafenib (n = 154) or placebo (n = 153) was added to transarterial chemoembolization (TACE) for patients with intermediate-stage HCC. Results were similar between the two arms for OS (HR, 0.898; 95% CI, 0.606-1.33) and for time to progression (TTP; HR, 0.797; 95% CI, 0.588-1.080).
In further attempts to expand upon the use of sorafenib, studies have assessed combination approaches. In the phase III CALGB-80802 study4 patients with advanced HCC received frontline sorafenib alone (n = 173) or in combination with doxorubicin (n = 173). Median OS with the combination was 8.9 months compared with 10.5 months with single-agent sorafenib (HR, 1.06; 95% CI, 0.8-1.4).
“There is not a role for adjuvant sorafenib, and there is no role for peri-TACE sorafenib,” said Abou-Alfa. “The role of sorafenib in the local regional setting was unfortunately negative, we didn't prove that additional sorafenib adds anything in that regard.”
Now, with sorafenib solidified as the frontline therapy for advanced HCC, phase III studies are exploring a host of second-line treatments, including the multikinase inhibitors cabozantinib (NCT01908426) and regorafenib (NCT01774344), the MET inhibitor tivantinib (NCT01755767), and the VEGFR2 inhibitor ramucirumab (NCT02435433). Additionally, phase II studies are looking at immune-based approaches in the second-line setting.
Immunotherapy on Horizon for HCC
“Work in the second-line setting is multi-faceted—immunotherapeutics are under evaluation and the molecular understanding of HCC is underway,” said Abou-Alfa.PD-L1 is expressed in 45% to 100% of patients with HCC. This expression is demonstrated on the tumor itself and the microenvironment, in Kupffer cells and tumor associated monocytes. Murine models and early clinical studies have shown promising efficacy for PD-L1 blockade. Additionally, evidence suggests that CTLA-4 blockade could also be an effective option.
In a phase II study,5 the CTLA-4 inhibitor tremelimumab showed signs of activity in 20 patients with HCC and chronic hepatitis C. The partial response rate was 17.6% with the immunotherapy and the disease control rate (DCR) was 76%. TTP was 6.5 months and a virologic response was indicated. However, grade 3 AST and ALT increases were seen in 45% of patients.
Adding to the early success seen with immunotherapy, the anti—PD-1 agent nivolumab (Opdivo) showed an objective response rate of 19%, which consisted of 2 complete responses for patients with pretreated advanced HCC.6 Stable disease was experienced by 48% of patients, for a DCR of 67%. These responses were observed regardless of hepatitis infection status.
“There are studies looking at anti—PD-L1 and anti–CTLA-4 and the combinations of the agents in a randomized, second-line setting,” said Abou-Alfa. “There is one other aspect that needs to be looked into, and that is the localized setting. This is an environment that is very poor inflammatory in nature, and probably adding an anti–PD-L1 in this setting would be of value.”
A phase II study is currently exploring the PD-L1 inhibitor durvalumab and tremelimumab alone or in combination for patients with unresectable HCC following prior sorafenib. The trial plans to enroll 120 patients, with an estimated completion date of April 2018 (NCT02519348).
A phase III study is also comparing nivolumab with sorafenib as a frontline therapy for patients with advanced HCC. This trial plans to enroll 726 patients with dual primary endpoints of OS and TTP. The primary completion date is July 2017 (NCT02576509).