Proton therapy for hepatocellular carcinoma

Radiation and Immune Checkpoint Inhibitors: Combination Therapy for Treatment of Hepatocellular Carcinoma

The liver tumor immune microenvironment has been thought to possess a critical role in the development and progression of hepatocellular carcinoma (HCC). Despite the approval of immune checkpoint inhibitors (ICIs), such as programmed cell death receptor 1 (PD-1)/programmed cell death ligand 1 (PD-L1) and cytotoxic T lymphocyte associated protein 4 (CTLA-4) inhibitors, for several types of cancers, including HCC, liver metastases have shown evidence of resistance or poor response to immunotherapies. Radiation therapy (RT) has displayed evidence of immunosuppressive effects through the upregulation of immune checkpoint molecules post-treatment. However, it was revealed that the limitations of ICIs can be overcome through the use of RT, as it can reshape the liver immune microenvironment. Moreover, ICIs are able to overcome the RT-induced inhibitory signals, effectively restoring anti-tumor activity. Owing to the synergetic effect believed to arise from the combination of ICIs with RT, several clinical trials are currently ongoing to assess the efficacy and safety of this treatment for patients with HCC.

Non-Surgical Locoregional Therapies Alone or in Combination with Systemic Therapy in Patients with Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the most common primary liver cancer, representing the third-leading cause of cancer-related deaths worldwide. Curative intent treatment options for patients with HCC include liver transplantation, resection and ablation of small lesions. Other potentially curative therapies include cryoablation, microwave ablation and percutaneous alcohol injection. For locally advanced disease, different arterially directed therapies including transarterial chemoembolization and selective internal radiation therapy, plus external beam radiation including three-dimensional conformal radiation therapy, intensity-modulated radiation therapy, stereotactic body radiation therapy and proton beam therapy, are available or studied. Systemic therapies based on checkpoint inhibitors and tyrosine kinase inhibitors are available for the management of metastatic HCC and sometimes for locally advanced disease. Combinations of locoregional therapies with systemic drugs are currently the subject of several clinical trials.

Targeting DNA-dependent protein kinase sensitizes hepatocellular carcinoma cells to proton beam irradiation through apoptosis induction

Recent studies have highlighted the implications of genetic variations in the relative biological effectiveness (RBE) of proton beam irradiation over conventional X-ray irradiation. Proton beam radiotherapy is a reasonable radiotherapy option for hepatocellular carcinoma (HCC), but the impact of genetic difference on the HCC RBE remains unknown. Here, we determined proton RBE in human HCC cells by exposing them to various doses of either 6-MV X-rays or 230-MeV proton beams. Clonogenic survival assay revealed variable radiosensitivity of human HCC cell lines with survival fraction at 2 Gy ranging from 0.38 to 0.83 and variable proton RBEs with 37% survival fraction ranging from 1.00 to 1.48. HCC cells appeared more sensitive to proton irradiation than X-rays, with more persistent activation of DNA damage repair proteins over time. Depletion of a DNA damage repair gene, DNA-PKcs, by siRNA dramatically increased the sensitivity of HCC cells to proton beams with a decrease in colony survival and an increase in apoptosis. Our findings suggest that there are large variations in proton RBE in HCC cells despite the use of a constant RBE of 1.1 in the clinic and targeting DNA-PKcs in combination with proton beam therapy may be a promising regimen for treating HCC.

Proton Beam Therapy and Carbon Ion Radiotherapy for Hepatocellular Carcinoma

Charged particle therapy with proton beam therapy (PBT) and carbon ion radiotherapy (CIRT) has emerged as a promising radiation modality to minimize radiation hepatotoxicity while maintaining high rates of tumor local control. Both PBT and CIRT deposit the majority of their dose at the Bragg peak with little to no exit dose, resulting in superior sparing of normal liver tissue. CIRT has an additional biological advantage of increased relative biological effectiveness, which may allow for increased hypofractionation regimens. Retrospective and prospective studies have demonstrated encouragingly high rates of local control and overall survival and low rates of hepatotoxicity with PBT and CIRT. Ongoing randomized trials will evaluate the value of PBT over photons and other standard liver-directed therapies and future randomized trials are needed to assess the value of CIRT over PBT.

Chest wall toxicity after hypofractionated proton beam therapy for liver malignancies

PURPOSE

Normal liver-sparing with proton beam therapy (PBT) allows for dose escalation in the treatment of liver malignancies, but it may result in high doses to the chest wall (CW). CW toxicity (CWT) data after PBT for liver malignancies are limited, with most published reports describing toxicity after a combination of hypofractionated proton and photon radiation therapy. We examined the incidence and associated factors for CWT after hypofractionated PBT for liver malignancies.

METHODS AND MATERIALS

We retrospectively reviewed the charts of 37 consecutive patients with liver malignancies (30 hepatocellular carcinoma, 6 intrahepatic cholangiocarcinoma, and 1 metastasis) treated with hypofractionated PBT. CWT was scored using Common Terminology Criteria for Adverse Events, version 4. Receiver-operating characteristic curves were used to identify patient and dosimetric factors associated with CWT and to determine optimal dose-volume histogram parameters/cutoffs. Cox regression univariate analysis was used to associate factors to time-dependent onset of CWT.

RESULTS

Thirty-nine liver lesions were treated with a median dose of 60 GyE (range, 35-67.5) in 15 fractions (range, 13-20). Median follow-up was 11 months (range, 2-44). Grade ≥2 and 3 CW pain occurred in 7 (19%) and 4 (11%) patients, respectively. Median time to onset of pain was 6 months (range, 1-14). No patients had radiographic rib fracture. On univariate analysis, CW equivalent 2 Gy dose with an α/β = 3 Gy (EQD2_α/β=3), V57 >20 cm³ (hazard ratio [HR], 2.7; P = .004), V63 >17 cm³ (HR, 2.7; P = .003), and V78 >8 cm³ (HR, 2.6; P = .003) had the strongest association with grade ≥2 CW pain, as did tumor dose of >75 Gy EQD2_α/β=10 (HR, 8.7; P = .03). No other patient factors were associated with CWT.

CONCLUSIONS

CWT after hypofractionated PBT for liver malignancies is clinically relevant. For a 15-fraction regimen, V47 >20 cm³, V50 >17 cm³, and V58 >8 cm³ were associated with higher rates of CWT. Further investigation of PBT techniques to reduce CW dose are warranted.

Proton beam therapy for hepatocellular carcinoma

INTRODUCTION

Radiation therapy is an effective treatment option for hepatocellular carcinoma (HCC) patients. However, radiotherapy for HCC still has limited recognition as a standard treatment option in international consensus guidelines due to a paucity of randomized controlled trials and the risk of hepatotoxicity, which is primarily mediated by baseline liver function and dose delivered to non-tumor liver cells. Proton beam therapy (PBT) may offer advantages over photon-based radiation treatments through its dosimetric characteristic of sparing more liver volume at low to moderate doses. PBT has the potential to reduce radiation-related hepatotoxicity and allow for tumor dose escalation. Areas covered: This article reviews the clinical rationale for using PBT for HCC patients and clinical outcome and toxicity data from retrospective and prospective studies. PBT-specific technical challenges for these tumors and appropriate selection of patients to be treated with PBT are discussed. Expert commentary: Local control, overall survival, and toxicity results are promising for liver PBT. Future studies, including ongoing randomized cooperative group trials, will aim to determine the incremental benefit of PBT over photons and which patients are most suitable for PBT.

Randomized Clinical Trial Comparing Proton Beam Radiation Therapy with Transarterial Chemoembolization for Hepatocellular Carcinoma: Results of an Interim Analysis

PURPOSE

To describe results of a planned interim analysis of a prospective, randomized clinical trial developed to compare treatment outcomes among patients with newly diagnosed hepatocellular carcinoma (HCC).

METHODS AND MATERIALS

Eligible subjects had either clinical or pathologic diagnosis of HCC and met either Milan or San Francisco transplant criteria. Patients were randomly assigned to transarterial chemoembolization (TACE) or to proton beam radiation therapy. Patients randomized to TACE received at least 1 TACE with additional TACE for persistent disease. Proton beam radiation therapy was delivered to all areas of gross disease to a total dose of 70.2 Gy in 15 daily fractions over 3 weeks. The primary endpoint was progression-free survival, with secondary endpoints of overall survival, local tumor control, and treatment-related toxicities as represented by posttreatment days of hospitalization.

RESULTS

At the time of this analysis 69 subjects were available for analysis. Of these, 36 were randomized to TACE and 33 to proton. Total days of hospitalization within 30 days of TACE/proton was 166 and 24 days, respectively (P<.001). Ten TACE and 12 proton patients underwent liver transplantation after treatment. Viable tumor identified in the explanted livers after TACE/proton averaged 2.4 and 0.9 cm, respectively. Pathologic complete response after TACE/proton was 10%/25% (P=.38). The 2-year overall survival for all patients was 59%, with no difference between treatment groups. Median survival time was 30 months (95% confidence interval 20.7-39.3 months). There was a trend toward improved 2-year local tumor control (88% vs 45%, P=.06) and progression-free survival (48% vs 31%, P=.06) favoring the proton beam treatment group.

CONCLUSIONS

This interim analysis indicates similar overall survival rates for proton beam radiation therapy and TACE. There is a trend toward improved local tumor control and progression-free survival with proton beam. There are significantly fewer hospitalization days after proton treatment, which may indicate reduced toxicity with proton beam therapy.

Deep Inspiration Breath Hold-Based Radiation Therapy: A Clinical Review

Several recent developments in linear accelerator-based radiation therapy (RT) such as fast multileaf collimators, accelerated intensity modulation paradigms like volumeric modulated arc therapy and flattening filter-free (FFF) high-dose-rate therapy have dramatically shortened the duration of treatment fractions. Deliverable photon dose distributions have approached physical complexity limits as a consequence of precise dose calculation algorithms and online 3-dimensional image guided patient positioning (image guided RT). Simultaneously, beam quality and treatment speed have continuously been improved in particle beam therapy, especially for scanned particle beams. Applying complex treatment plans with steep dose gradients requires strategies to mitigate and compensate for motion effects in general, particularly breathing motion. Intrafractional breathing-related motion results in uncertainties in dose delivery and thus in target coverage. As a consequence, generous margins have been used, which, in turn, increases exposure to organs at risk. Particle therapy, particularly with scanned beams, poses additional problems such as interplay effects and range uncertainties. Among advanced strategies to compensate breathing motion such as beam gating and tracking, deep inspiration breath hold (DIBH) gating is particularly advantageous in several respects, not only for hypofractionated, high single-dose stereotactic body RT of lung, liver, and upper abdominal lesions but also for normofractionated treatment of thoracic tumors such as lung cancer, mediastinal lymphomas, and breast cancer. This review provides an in-depth discussion of the rationale and technical implementation of DIBH gating for hypofractionated and normofractionated RT of intrathoracic and upper abdominal tumors in photon and proton RT.

The strategies for treating primary hepatocellular carcinoma with portal vein tumor thrombus

PURPOSE

To further improve the effectiveness and prognosis of primary hepatocellular carcinoma (HCC) with portal vein tumor thrombus (PVTT), the current status of treatment for HCC with PVTT was reviewed.

METHODS

A Medline search was undertaken to identify articles using the keywords "HCC", "PVTT" and "therapy". Additional papers were identified by a manual search of the references from the key articles.

RESULTS

PVTT, as a common complication of HCC, was divided into type I ∼ IV. The therapeutic approach is mainly composed of five types: surgical resection, regional interventional therapy, radiotherapy, combination therapy, targeted therapy. All of these therapeutic approaches were separately evaluated in detail.

CONCLUSIONS

For those resectable tumors, the better choice for treatment of HCC with PVTT should be hepatectomy and removal of PVTT. For those unresectable tumors, TACE (especially the super-selective TACE) has been the preferred palliative treatment, the other regional interventional therapy and/or radiotherapy could improve the therapeutic effects. The multidisciplinary treatments may further improve the quality of life and prolong the survival period for the HCC patients associated with PVTT.

Charged particle therapy versus photon therapy for patients with hepatocellular carcinoma: a systematic review and meta-analysis

PURPOSE

To perform a systematic review and meta-analysis to compare the clinical outcomes and toxicity of hepatocellular carcinoma (HCC) patients treated with charged particle therapy (CPT) with those of individuals receiving photon therapy.

METHODS

We identified relevant clinical studies through searching databases. Primary outcomes of interest were overall survival (OS) at 1, 3, 5 years, progression-free survival (PFS), and locoregional control (LC) at longest follow-up.

RESULTS

73 cohorts from 70 non-comparative observational studies were included. Pooled OS was significantly higher at 1, 3, 5 years for CPT than for conventional radiotherapy (CRT) [relative risk (RR) 1·68, 95% CI 1·22-2·31; p<0·001; RR 3.46, 95% CI: 1.72-3.51, p<0.001; RR 25.9, 95% CI: 1.64-408.5, p=0.02; respectively]. PFS and LC at longest follow-up was also significantly higher for CPT than for CRT (p=0·013 and p<0.001, respectively), while comparable efficacy was found between CPT and SBRT in terms of OS, PFS and LC at longest follow-up. Additionally, high-grade acute and late toxicity associated with CPT was lower than that of CRT and SBRT.

CONCLUSION

Survival rates for CPT are higher than those for CRT, but similar to SBRT in patients with HCC. Toxicity tends to be lower for CPT compared to photon radiotherapy.

Transarterial Fiducial Marker Placement for Image-guided Proton Therapy for Malignant Liver Tumors

PURPOSE

The aim of this study is to analyze the technical and clinical success rates and safety of transarterial fiducial marker placement for image-guided proton therapy for malignant liver tumors.

METHODS AND MATERIALS

Fifty-five patients underwent this procedure as an interventional treatment. Five patients had 2 tumors, and 4 tumors required 2 markers each, so the total number of procedures was 64. The 60 tumors consisted of 46 hepatocellular carcinomas and 14 liver metastases. Five-mm-long straight microcoils of 0.018 inches in diameter were used as fiducial markers and placed in appropriate positions for each tumor. We assessed the technical and clinical success rates of transarterial fiducial marker placement, as well as the complications associated with it. Technical success was defined as the successful delivery and placement of the fiducial coil, and clinical success was defined as the completion of proton therapy.

RESULTS

All 64 fiducial coils were successfully installed, so the technical success rate was 100 % (64/64). Fifty-four patients underwent proton therapy without coil migration. In one patient, proton therapy was not performed because of obstructive jaundice due to bile duct invasion by hepatocellular carcinoma. Thus, the clinical success rate was 98 % (54/55). Slight bleeding was observed in one case, but it was stopped immediately and then observed. None of the patients developed hepatic infarctions due to fiducial marker migration.

CONCLUSION

Transarterial fiducial marker placement appears to be a useful and safe procedure for proton therapy for malignant liver tumors.

Abnormal expression of insulin-like growth factor-I receptor in hepatoma tissue and its inhibition to promote apoptosis of tumor cells

Abnormal signaling of insulin-like growth factor I receptor (IGF-IR) is associated with hepatocellular carcinoma, but the underlying molecular mechanisms remain largely unknown. The objective of this study was to investigate IGF-IR's role as a signaling molecule, its pathological alteration in hepatoma tissues, and its effect on hepatoma cell proliferation when inhibited. As measured by immunohistochemical analysis, the incidence of hepatic IGF-IR expression in cancerous tissue was 80.0 % (24 of 30), which was significantly higher (P < 0.05) than 43.3 % (13 of 30) occurrence in the surrounding tissue and the nondetectable (0 of 30) frequency in the distal cancerous tissue. Hepatoma IGF-IR expression was correlated to the differentiation degree and not to the number or size of tumors, HBV infection, and AFP level. The in vitro IGF-IR expression in hepatoma cells was down-regulated significantly by picropodophyllin, a specific kinase inhibitor, in a time- and dose-dependent manner. Cell proliferation was inhibited through typical mechanisms of promoting apoptosis and cell cycle arrest (G2/M phase). Up-regulation of IGF-IR in hepatocarcinogenesis suggests that the down-regulation of IGF-IR expression could be a specific molecular target for hepatoma cell proliferation.

Antitumor efficacy of C-X-C motif chemokine ligand 14 in hepatocellular carcinoma in vitro and in vivo

C-X-C motif chemokine ligand 14 (CXCL14) is a novel gene that is expressed in many normal cells but is absent from or expressed at very low levels in cancerous tissues such as head and neck squamous cell carcinoma (HNSCC), prostate cancer, and pancreatic cancer. However, the relationship between CXCL14 and hepatocellular carcinoma (HCC) remains unclear. Therefore, the exact function of CXCL14, which may modulate antitumor immune responses in certain cancers, was evaluated. CXCL14 was downregulated in HCC tissues compared to adjacent normal tissues. Moreover, overexpression of CXCL14 had an inhibitory effect on cell proliferation, induced apoptosis and inhibited the invasion of HCC cells in vitro. Upregulation of CXCL14 by lentivirus also significantly suppressed the growth of subcutaneous tumors in nude mice in vivo. We further demonstrated that the loss of CXCL14 expression was regulated by promoter hypermethylation. CXCL14 induced tumor cell apoptosis through both the mitochondrial and nuclear apoptosis pathways. CXCL14 suppressed tumor cell proliferation through regulation of the cell cycle by downregulation of cyclins and cyclin-dependent kinases. In conclusion, CXCL14 plays a pivotal role as a potential tumor suppressor in HCC. The re-expression or upregulation of this gene may provide a novel strategy in HCC therapy in the future.

Treatment with heavy charged particles: systematic review of clinical data and current clinical (comparative) trials

BACKGROUND

To analyze relevant data on carbon ion radiotherapy for different tumor indications and to review current clinical trials.

MATERIAL AND METHODS

All published data on carbon ion radiotherapy were searched for with specific criteria in PUBMED. The terms for search were 'carbon ion and (radiotherapy OR radiation therapy) and (nirs OR chiba OR japan OR itep OR st. petersburg OR PSI OR dubna OR uppsala OR clatterbridge OR loma linda OR nice OR orsay OR itemba OR mpri OR himac OR triumf OR GSI OR HMI OR NCC OR ibmc OR pmrc OR MGH OR infn-lns OR shizuoka OR werc OR zibo OR md anderson OR fpti OR ncc ilsan OR boston OR heidelberg OR tsukuba) NOT in vitro NOT cell culture NOT review[Publication Type] Filters: Humans, English'. The search delivered 273 hits, of which only articles in English including 20 or more patients were included. Case reports were not considered. We subdivided into disease- and site-specific groups.

RESULTS AND CONCLUSION

To date, several studies have been performed, however, no randomized trials have been conducted. Therefore, carbon ion radiotherapy must be considered an experimental treatment, and randomized trials comparing modern photon as well as proton treatments are necessary.