Based on the fact that somatostatin (SST) analogs have given promising results for treatment of hepatocellular cancer, we performed both in vitro and in vivo investigations to define the role of a depot formulation of the long acting SST-analog lanreotide (LAN). A decrease of cells in the S-phase as compared to controls (p<0.03) followed by a significant, dose-dependent induction of apoptosis could be demonstrated in Hep G2 cells along with a dose-dependent influence of the peptide on cellular proliferation. Northern blotting demonstrated the presence of mRNA for SSTR subtypes 2, 3 and 4 in Hep G2 cells, but only slight SSTR expression in normal liver tissue. In addition, 21 untreated patients with advanced HCC not amenable to surgery were administered 30 mg of LAN by deep intramuscular injection every 14 days until documented disease progression. Fifteen of these patients also underwent scanning with commercially available 111In-DTPA-D-Phe1-Octreotide (111In-OCT) to define the in vivo expression of SSTR. No positive 111In-OCT scans were obtained, indicating the absence of relevant amounts of functional SSTR2 in HCC. One patient (5%) showed a partial response to treatment, 8 patients had stable disease (38%), while the remaining patients progressed during treatment. The median survival was 4.2 months (range 1.2-13+), and the median time to progression was 2.5 months (range, 1.5-7+). However, 4 patients (19%) had an increase in WHO performance status lasting between 2.5 and 6 months, 5 patients (24%) had an increase in body weight, while pain markedly improved in 1 additional patient (5%). In total, 5 patients (24%) had a decrease in serum-AFP levels by at least 30%. Our results clearly indicate the ability of LAN to decrease the S-phase fraction along with induction of apoptosis in Hep G2 cells in a dose-dependent manner. Our data suggest clinical potential of SST-analogs in HCC and indicate that suboptimal doses of the peptide might have been administered in our series.

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