To investigate efficacy and toxicity of regorafenib after treatment with atezolizumab and bevacizumab combination

• There is preclinical and clinical data on synergistic activity of angiogenesis inhibitors and anti-programmed death-1 (anti-PD-1) targeted therapy. Targeting VEGFR decreased T-regulatory cells and Myeloid-derived suppressor Cells. In addition, VEGF-A produced in the tumor microenvironment enhanced expression of PD-1 involved in CD8 T cell exhaustion8. The combination of targeted therapy and immune-checkpoint inhibitors (ICIs), either in a parallel or sequential manner, could theoretically lead to enhanced anti-tumor responses, reflected in durable responses and prolonged survival. However, there have been lack of clinical data of targeted agents who developed progressive disease with ICIs.
• In previous phase I study, pharmacodynamics indicated a sustained occupancy of > 70% of PD-1 molecules on circulating T-cells ≥ 2 months following infusion. Based on these findings, ICI use may retain the prolonged effect even after discontinuation. There was a case report of a sorafenib-refractory patient experiencing progressive disease during ICI combination treatment with the anti-PD-1 antibody and the anti-GITR antibody within phase I trial followed by a prolonged tumor response during third-line regorafenib monotherapy.
• In patients with advanced HCC, anti-VEGF monoclonal antibodies, multi-kinase inhibitor (sorafenib, regorafenib, cabozantinib and lenvatinib) and ICIs are available treatment options, however, treatment sequencing and combination strategy are challenging.
• Atezolizumab plus bevacizumab demonstrated survival benefit and established as a new first-line therapy, hence it is clinically important to study the efficacy and toxicity of regorafenib after treatment with ICIs or ICI combination.

Inclusion Criteria:

1. Diagnosis of HCC according to AASLD guidelines

2. Disease that is not amenable to a curative treatment (e.g. surgery, transplant, radiofrequency ablation)

3. Prior treatment with atezolizumab plus bevacizumab combination as 1st line treatment for unresectable HCC

4. Progression after atezolizumab plus bevacizumab treatment, The duration of atezolizumab plus bevacizumab must be 2 consecutive treatment cycles or more

5. Recovery to ≤ Grade 1 from toxicities related to any prior treatments, unless the adverse events are clinically non-significant and/or stable on supportive therapy

6. Life expectancy of 12 weeks or longer

7. Age ≥ 19 years old

8. ECOG performance status of 0, 1

9. Adequate hematological function

   1. Absolute neutrophil count (ANC) ≥ 1.5 x109/L
   2. Platelets ≥ 75 x 109/L
   3. Hemoglobin ≥ 10 g/dL

10. Adequate renal function

    1. serum creatinine ≤ 1.5 × upper limit of normal or calculated creatinine clearance ≥ 40 mL/min (using the Cockroft-Gault equation) AND
    2. urine protein/creatinine ratio (UPCR) ≤ 1 mg/mg (≤ 113.1 mg/mmol) or 24-hour urine protein < 1 g

11. Child-Pugh Score of 5 or 6

12. Total bilirubin ≤ 2 mg/dL (≤ 34.2 μmol/L)

13. Serum albumin > 2 g/dL (> 20 g/L)

14. Alanine aminotransferase (ALT) < 3.0 upper limit of normal (ULN)

15. Antiviral therapy per local standard of care if active hepatitis B (HBV) infection

16. Capable of understanding and complying with the protocol requirements and signed informed consent

17. Sexually active fertile subjects and their partners must agree to use medically accepted methods of contraception (e.g., barrier methods, including male condom, female condom, or diaphragm with spermicidal gel) during the course of the study and for 4 months after the last dose of study treatment

18. Female subjects of childbearing potential must not be pregnant at screening.

Exclusion Criteria:

1. Fibrolamellar carcinoma or mixed hepatocellular cholangiocarcinoma

2. Prior regorafenib treatment

3. Prior systemic treatment for HCC, except for atezolizumab plus bevacizumab (i.e. regorafenib must be 2nd line systemic treatment)

4. Known brain metastases or cranial epidural disease unless adequately treated with radiotherapy and/or surgery (including radiosurgery) and stable for at least 3 months before randomization.

5. Concomitant anticoagulation, at therapeutic doses, with anticoagulants such as warfarin or warfarin-related agents, low molecular weight heparin (LMWH), thrombin or coagulation factor X (FXa) inhibitors, or antiplatelet agents (eg, clopidogrel). Low dose aspirin for cardioprotection (per local applicable guidelines), low-dose warfarin (≤ 1 mg/day), and low dose LMWH are permitted.

6. The subject has uncontrolled, significant intercurrent or recent illness including, but not limited to, the following conditions:

   a. Cardiovascular disorders including i. Symptomatic congestive heart failure, unstable angina pectoris, or serious cardiac arrhythmias ii. Uncontrolled hypertension defined as sustained BP > 150 mm Hg systolic, or > 100 mm Hg diastolic despite optimal antihypertensive treatment iii. Stroke (including TIA), myocardial infarction, or other ischemic event within 6 months iv. Thromboembolic event within 3 months. Subjects with thromboses of portal/hepatic vasculature attributed to underlying liver disease and/or liver tumour are eligible b. Gastrointestinal (GI) disorders including those associated with a high risk of perforation or fistula formation/bleeding: i. Tumours invading the GI tract, active peptic ulcer disease, inflammatory bowel disease, diverticulitis, cholecystitis, symptomatic cholangitis or appendicitis, acute pancreatitis or acute obstruction of the pancreatic duct or common bile duct, or gastric outlet obstruction ii. Abdominal fistula, GI perforation, bowel obstruction, intra-abdominal abscess within 6 months

7. Major surgery within 2 months before randomization. Complete healing from major surgery must have occurred 1 month before randomization. Complete healing from minor surgery (eg, simple excision, tooth extraction) must have occurred at least 7 days before registration. Subjects with clinically relevant co d. Cavitating pulmonary lesion(s) or endobronchial disease

8. Lesion invading a major blood vessel (eg, pulmonary artery or aorta)

9. Clinically significant bleeding risk including the following within 28 days of registration: hematuria, hematemesis, hemoptysis of >0.5 teaspoon (>2.5 mL) of red blood, or other signs indicative of pulmonary hemorrhage, or history of other significant bleeding if not due to reversible external factors

10. Gastric or esophageal varices that require interventional treatment within 28 days prior to registration. Prophylaxis with pharmacologic therapy (e.g. non-selective beta blocker) is permitted.

11. Moderate or severe ascites (Radiologically detected but clinically insignificant ascites is allowed)

12. Corrected QT interval calculated by the Fridericia formula (QTcF) > 500 ms within 21 days of registration

    * If the QTcF is > 500 ms in first ECG, a total of 3 ECGs should be performed. If the average of these 3 consecutive results for QTcF is ≤ 500 ms, the subject meets eligibility in this regard.

13. Previously identified allergy or hypersensitivity to components of the study treatment formulations

14. Pregnant or lactating females

15. Diagnosis of another malignancy within 2 years before randomization, except for superficial skin cancers, or localized, low-grade tumors deemed cured and not treated with systemic therapy

16. Other clinically significant disorders that are judged by investigators to be unsuitable for the clinical trial