Interferon-alpha 2b: An Effective Treatment for Hepatic Epithelioid Hemangioendothelioma

Background: Hepatic epithelioid hemangioendothelioma (HEH) is a rare tumor and no standard treatment has been established. This study was aimed to prospectively investigate the effect of interferon-alpha 2b (IFN-a 2b) for HEH patients. Methods: Since March 2014, a total of 62 pathologically diagnosed HEH patients were followed up regularly. IFN-a 2b was suggested to HEH patients with progressed disease. Safety was assessed each month and tumor assessment scan was performed every 3 months. The primary end point was objective response rate (ORR) and disease control rate (DCR). Results: A total of 42 HEH patients were �nally included in this study. Median patient age was 35.5 years (range 18-65 years old). No severe (grade ≥ 3) adverse event (AE) of IFN-a 2b was reported in the whole group. The most common treatment-related AEs were fever (50.0%) and fatigue (21.4%). Two patients had grade 2 level hypothyroidism and 1 patient had grade 2 level of leukopenia and thrombocytopenia. Partial response and complete response were achieved in 20 (47.6%) and 2 (4.8%) patients, respectively, and the ORR was 52.4%. Stable disease was observed in 12 (28.6%) patients and the DCR was 81.0%. Progressive disease was observed in 8 (19.0%) patients. The 1, 3 and 5-year progression free rate were 81.0%, 69.2% and 62.3%, respectively. Only 1 patient died due to the progression of disease during the study. The1, 3 and 5-year overall survival rate were 100%, 97.2% and 97.2%, respectively. Conclusion: IFN-a 2b is a safe and effective treatment for HEH patients.


Background
Epithelioid hemangioendothelioma (EH) was initially described in 1982 by Weiss and Enzinger [1] and it can involve both soft tissues and visceral organs, including liver, lung, spleen and heart.Hepatic epithelioid hemangioendothelioma (HEH) is an extremely rare tumor (estimated incidence of less than one in 1,000,000 worldwide) with a clinical course intermediate between benign hemangioma and angiosarcoma [2] .Surgical resection, liver transplantation, chemotherapy, and immunotherapy have all been implemented in HEH patients.However, due to the scarcity of the disease and di culty of patients' inclusion, prospective clinical trial is very hard to conduct.Liver transplantation has been reported to achieve a satisfying long-term survival for HEH patients [3][4][5][6][7] .But the shortage of organ donation limits the accessibility of liver transplantation for most HEH patients, unless they are in critical condition.Clinical researches regarding to surgical resection, anti-angiogenesis drugs, chemotherapy or transarterial embolization (TAE) have been reported with indeterminate results [8][9][10][11] .At present, no standard treatment has been established for HEH patients yet.interferon-alpha 2b (IFN-a 2b) as an immunotherapy has been used for the treatment of hematological malignancies [12] .IFN-a therapy for EH has also been proposed for tumor reduction and metastasis prevention [9,13,14] .Since 2014, our team has been investigating HEH patients and a total of 62 are under regular follow-up now.According to our previous experience, IFN-a 2b showed effective responses in some HEH patients, but the result needs prospective veri cation in a larger group of patients.This study was aimed to prospectively investigate the effect of IFN-a 2b in the treatment of HEH patients, which may provide valid evidence for future clinical practice.

Patients And Methods
Since March 2014, a total of 62 pathologically diagnosed HEH patients have been investigated and followed up regularly.As no standard treatment has been established for HEH, IFN-a 2b was suggested to HEH patients who have progressed disease or reoccurrence after previous treatment.The inclusion criteria comprised the following: histologically con rmed HEH; tumor progression or reoccurrence; at least 1 measurable target lesion according to Response Evaluation Criteria in Solid Tumors Committee (RECIST) criteria [15] ; Eastern Cooperative Oncology Group performance status (ECOG PS) of 0 or 1.
Patients received IFN-a 2b 300 million units by subcutaneous injection once every other day.Tolerability and safety were assessed each month by interviewing and monitoring the blood cell counts, liver, thyroid and renal function until month 6 and then every 3 months.Tumor assessment scan including computed tomography (CT) and magnetic resonance imaging (MRI) was performed every 3 months and treatment decisions were based on RECIST.Treatment was continued until disease progression, development of unacceptable toxicity or termination of patients' decision.For HEH patients with extrahepatic metastases, the assessment was based on the intrahepatic lesions.The primary end point was objective response rate (ORR) and disease control rate (DCR).The secondary end points included 1, 3 and 5-year progression free rate and survival rate.Safety assessments consisted of the monitoring and recording of adverse event (AE) according to Common Terminology Criteria for Adverse Events version 4.03, laboratory evaluations and vital signs.
The study protocol was approved by the ethics committee of China-Japan Friendship Hospital, and the study was conducted in accordance with the principles of the Declaration of Helsinki and Good Clinical Practice Guidelines.

Statistical Analysis
Progression free survival and overall survival were estimated using the Kaplan-Meier method.All statistical analyses were performed using SAS version 9.4 (SAS Institute, Cary, NC).

Patients
Overall, a total of 62 HEH patients were regularly followed up in our clinic and 42 HEH patients with progressed disease or reoccurrence were nally included in this study.Median patient age was 36 years (range 18-65 years old) and patients' gender was almost equally distributed (male 52.4% and female 47.6%).Tumor progression was observed in 25 patients during observation with no treatment and in 6 patients after the treatment of chemotherapy or TAE.Reoccurrence was detected in 11 patients after curatively intended surgery or radiofrequency ablation (RF).The median time between diagnosis and treatment of IFN-a 2b was 9 months (range 2-57 months).
At baseline, all 42 patients had ECOG PS 0 with no severe liver injury.Mild abdominal pain occurred in 9 patients, but no other symptom was recorded.Extrahepatic metastases were detected in 23 patients and 50% patients had lung metastases (Table 1).
For the 34 patients with disease control, treatment of IFN-a 2b has been terminated in 21 patients (PR 14, CR 2 and SD 5), and all of the termination was conducted according to patients' decision except for the 2 patients with CR.Treatment of IFN-a 2b is still continued in 13 patients (PR 6, SD 7).For the 8 patients with PD, targeted therapy was used in 4 patients, while the others chose to observe.
PD was detected in 4 of the 21 patients who stopped the treatment IFN-a 2b, and the time was 10, 12, 12 and 36 months after the termination of IFN-a 2b, respectively.The 1, 3 and 5-year progression free rate were 81.0%, 69.2% and 62.3%, respectively.Only 1 patient died due to the progression of disease during the study.The1, 3 and 5-year survival rate were 100%, 97.2% and 97.2%, respectively (Fig. 2).The detailed information and radiological changes of the whole group were provided in Supplemental File 1 and 2.

Discussion
HEH is an extremely rare hepatic tumor with varying biological behavior.Currently, there is no effective indicator to predict the malignancy.For most HEH patients, the tumor progresses slowly with no severe clinical symptoms.Due to the rarity of the disease, HEH patients were commonly misdiagnosed as metastatic carcinoma.Although several studies have reported the radiological characteristics of HEH [16- 19] , con rmed diagnosis still rely on the pathological examination.
No standard treatment has been established for HEH patients yet.Liver transplantation was reported to be an effective treatment with acceptable long-term outcomes [4,7,20,21] .However, the scarcity of organ donation limits the accessibility of liver transplantation for HEH patients.Surgical resection was another treatment option, but the long-term results were not well [22][23][24] .Moreover, curative surgery is implausible for most HEH patients because of the multicentricity of the tumor.Studies regarding to chemotherapy, targeted therapy or immunotherapy have been reported, but the results were undetermined [10,[25][26][27][28][29][30][31][32] .Thalidomide as anti-angiogenic therapy has also been reported to control tumor progression, but tumor response has seldom been achieved [8,[33][34][35][36] ].
IFN-a 2b as an immunotherapy has been used for the treatment of hematological malignancies [12] .IFN-a therapy for EH has also been proposed for tumor reduction and metastasis prevention [9,13,14] .Kayler et al reported that IFN-α was used for treatment of metastatic HEH after liver transplantation [37] .IFN-a has also been reported to have antiproliferative activity through cancer cell growth inhibition, activation of immune cells, inhibition of vascularization, and induction of cytokines [12,38] .
Since 2014, a total of 42 HEH patients with progressed disease have received the treatment of IFN-a 2b.In this study, PR and CR were observed in 22 patients with an ORR of 52.4%.SD was observed in 12 patients and the DCR was 81.0%.Based on our knowledge, this is the most effective medicine ever reported for HEH patients.Moreover, comparing to previous studies of liver transplantation which reported the 5-year survival rate of 70-83% [4,7] , the HEH patients in this study achieved a 5-year survival rate of 97.2%.Although the median follow-up time was only 33 months in this study, the tendency of better long-term survival could be speculated.Moreover, the safety of long-term treatment with IFN-a 2b was fully veri ed.The median duration of IFN-a 2b was 19 months and no severe (grade ≥ 3) AE was recorded.Considering the risk of hypothyroidism, serum level of thyroxin should be monitored regularly.
The anti-tumor mechanism of IFN-a 2b is not fully investigated or understood, but the encouraging result of this study will provide evidence-based treatment suggestion for HEH patients.Since EH also happens in other organs such as lung and bone, further clinical study could be designed to verify the effect of IFNa 2b for other EH patients.However, due to the scarcity of EH, inclusion of patients would be a hard longperiod work.
There are two major limitations about this study.First, the disease is so rare that the group of HEH patients live across the whole country.For some patients who are very far from our center, they prefer to perform regular blood tests and radiological examination in local medical institution, and send us the images and results, which could lead to the potential inaccuracy of radiological comparison.Second, the IFN-a 2b that the HEH patients used were not from the same pharmaceutical company.They purchased the IFN-a 2b which local medical institution could provide and the dosage was the same.Although there are the limitations we mentioned above, the results of this study still provide valuable clinical evidence for the treatment of HEH.

Conclusion
IFN-a 2b is a safe and effective treatment for HEH patients.Because of the extreme scarcity of the disease, randomized clinical trial would be unrealistic.Although this was a single-arm study, the results still provided valuable clinical evidence for the treatment of HEH patients.The encouraging result of IFN-a 2b makes it a promising option for other EH patients and further clinical trial is needed.

Figures Figure 1
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Table 1
Baseline demographic and clinical characteristics of patients receiving IFN-a 2b (N = 42) AE of IFN-a 2b was reported in the whole group.The most common treatmentrelated AEs were fever (50.0%) and fatigue (21.4%).Mostly, fever only occurred in the rst several shots and disappeared one month later.Lasting fever was not recorded.The other AEs included leukopenia, IFN-a 2b, interferon-alpha 2b; ALT, alanine aminotransferase; AST, aspartate aminotransferase; TB, total bilirubin; ALP, alkaline phosphatase; GGT, gamma-glutamyl transpeptidase; thrombocytopenia, alopecia, rash, decreased appetite, anemia and hypothyroidism (Table2).Two patients had grade 2 level hypothyroidism and 1 patient had grade 2 level of leukopenia and thrombocytopenia.Thirteen patients (31.0%) had no treatment-related AE.Treatment related AEs which led to the interruption of IFN-a 2b occurred in no patient.