# In vitro properties of patient serum predict clinical outcome after high dose rate brachytherapy of hepatocellular carcinoma

## TL;DR

This study shows that patient serum after HDR-BT affects cancer cell growth in the lab, with changes linked to treatment outcomes in liver cancer patients.

## Contribution

The study introduces a novel in vitro method to predict clinical outcomes of HDR-BT in hepatocellular carcinoma using patient serum.

## Key findings

- Nonresponders showed increased BrdU incorporation in Huh7 and HepG2 cells compared to responders.
- High BrdU incorporation in serum-exposed cells correlated with shorter time to systemic progression in patients.
- Cyclin E expression in HepG2 cells varied between responders and nonresponders after HDR-BT.

## Abstract

Tumor recurrence after local tumor ablation, including high dose rate brachytherapy (HDR‐BT), represents a substantial challenge in hepatocellular carcinoma (HCC) treatment. This study aimed to investigate whether induced factors that appear in patient serum after HDR‐BT alter HCC growth in vitro, and whether this correlates with outcome. In total, 23 HCC patients [Barcelona clinic liver cancer (BCLC) stage A or B] were treated by HDR‐BT (1 × 15 Gy) and classified as responders in case of no progression within 6 months and no diffuse systemic progression within 2 years (n = 12), or nonresponders with recurrence within 6 months and/or diffuse systemic tumor progression or extrahepatic disease within 2 years (n = 11). Patient serum was obtained at baseline and 48 h postprocedure. Two hepatoma cell lines (Huh7, HepG2) were incubated for 72 h in the presence of 20% serum. BrdU incorporation was assessed for serum incubation at baseline and 48 h post‐HDR‐BT. BrdU incorporation post‐HDR‐BT compared to baseline was significantly elevated in nonresponders compared to responders for both Huh7 and HepG2. Likewise, confirmatory Cyclin E studies revealed different induction kinetics between a subset of representative responders and nonresponders in HepG2. Time to systemic progression (TTSP) in patients with increased BrdU incorporation was significantly shorter compared to patients with decreased BrdU incorporation after serum incubation. These data indicate that poor outcome following HDR‐BT is associated with increased measurable proliferation parameters of hepatoma cell lines in vitro after exposure to patient serum, offering insights into post‐treatment tumor biology and a potential biomarker of clinical outcome.

Following high dose rate brachytherapy (HDR‐BT) for hepatocellular carcinoma (HCC), patients were classified as responders and nonresponders. Post‐therapy serum induced increased BrdU incorporation and Cyclin E expression of Huh7 and HepG2 cells in nonresponders, but decreased levels in responders. High BrdU incorporation was associated with shorter time to systemic progression (TTSP) and elevated plasma levels of PTN and CRTAM.