Recurrence of Hepatocellular Carcinoma After Complete Radiologic Response to Trans-Arterial Embolization: A Retrospective Study on Patterns, Treatments, and Prognoses

BACKGROUND

There is limited information about the long-term outcomes and patterns of progression in patients who have unresectable, liver-confined hepatocellular carcinoma (HCC) with complete response (CR) to transarterial embolization and do not undergo resection or transplantation (LT).

METHODS

A retrospective review analyzed participants in a randomized trial comparing hepatic artery embolization (HAE) and drug-eluting bead transarterial chemoembolization (DEB-TACE) with doxorubicin who had CR according to modified response evaluation criteria in solid tumors (mRECIST). The overall survival (OS), incidence and patterns of progression, and factors associated with progression were assessed.

RESULTS

Of the 101 patients in the trial, 37 with CR were included in this study. This cohort had 17 patients treated with HAE (46 %), and 20 patients managed with DEB-TACE (54 %). The median age was 67 years (range, 42-82 years). Most of the cohort were male (86.5 %) and Caucasian (78 %). The median pre-treatment Model for End-Stage Liver Disease (MELD) score was 10, and 70 % of the cohort had Barcelona Clinic Liver Cancer (BCLC) stage B or C. The median follow-up period was 49 months (95 % confidence interval [CI], 9-108 months), and the median OS was 25 months (95 % CI, 18.9-30.9 months). The 3- and 5-year survival rates were respectively 31 % (95 % CI, 16.7-45.9 %) and 18 % (95 % CI, 6.8-32.1 %). The 1- and 2-year cumulative incidences of progression were respectively 76 % (95 % CI, 57.7-86.8 %) and 92 % (95 % CI, 74.5-97.6 %). The most common first site of progression was the previously treated hepatic site or local site (32 %, 12/37). The 3-year cumulative incidence of progression was 65 % (95 % CI, 46.4-78.4 %) for the local site.

CONCLUSION

Patients with advanced-stage HCC and CR to embolization do not have durable responses and experience inevitable disease progression. Most patients with progression have liver-confined disease and should be evaluated for additional consolidative treatments.

A novel protein isoform of the RON tyrosine kinase receptor transforms human pancreatic duct epithelial cells

The MST1R gene is overexpressed in pancreatic cancer producing elevated levels of the RON tyrosine kinase receptor protein. While mutations in MST1R are rare, alternative splice variants have been previously reported in epithelial cancers. We report the discovery of a novel RON isoform discovered in human pancreatic cancer. Partial splicing of exons 5 and 6 (P5P6) produces a RON isoform that lacks the first extracellular immunoglobulin-plexin-transcription domain. The splice variant is detected in 73% of xenografts derived from pancreatic adenocarcinoma patients and 71% of pancreatic cancer cell lines. Peptides specific to RON P5P6 detected in human pancreatic cancer specimens by mass spectrometry confirm translation of the protein isoform. The P5P6 isoform is found to be constitutively phosphorylated, present in the cytoplasm, and it traffics to the plasma membrane. Expression of P5P6 in immortalized human pancreatic duct epithelial (HPDE) cells activates downstream AKT, and in human pancreatic epithelial nestin-expressing cells, activates both the AKT and MAPK pathways. Inhibiting RON P5P6 in HPDE cells using a small molecule inhibitor BMS-777607 blocked constitutive activation and decreased AKT signaling. P5P6 transforms NIH3T3 cells and induces tumorigenicity in HPDE cells. Resultant HPDE-P5P6 tumors develop a dense stromal compartment similar to that seen in pancreatic cancer. In summary, we have identified a novel and constitutively active isoform of the RON tyrosine kinase receptor that has transforming activity and is expressed in human pancreatic cancer. These findings provide additional insight into the biology of the RON receptor in pancreatic cancer and are clinically relevant to the study of RON as a potential therapeutic target.