Trial of TRC105 and Sorafenib in Patients With HCC

Sorafenib is an oral multikinase inhibitor targeting several receptor tyrosine kinases,
including the VEGF receptor (VEGFR), implicated in pathologic angiogenesis, tumor growth, and
cancer progression. Sorafenib is approved for the treatment of unresectable hepatocellular
carcinoma (HCC). TRC105 is an antibody to endoglin, an important angiogenic target on
proliferating endothelial cells that is distinct from VEGFR. TRC105 inhibits angiogenesis,
tumor growth and metastases and complements the activity of bevacizumab and multi-kinase
inhibitors that target the VEGFR in preclinical models. Together, the use of TRC105 with
sorafenib may result in more effective angiogenesis inhibition and improved clinical efficacy
over that seen with sorafenib alone.

Inclusion Criteria:

1. Patients must have confirmed hepatocellular carcinoma (HCC) by histopathology or
imaging criteria according to AASLD guidelines.

2. Patients must have disease that is not amenable to potentially curative resection or
ablative techniques or that has recurred following ablative techniques. In addition,
disease must not be amenable to transhepatic arterial chemoembolization (TACE) or must
have progressed on TACE. Patients must not be candidates for liver transplantation.

3. If liver cirrhosis is present, patient must have a Child-Pugh A or B (7 points)
classification.

4. No other prior malignancy is allowed except for the following: adequately treated
basal cell or squamous cell skin cancer, adequately treated Stage I or II cancer from
which the patient is currently in complete remission per investigators' clinical
judgment.

5. Measurable disease by RECIST 1.1 (Phase 2 only)

6. Age of 18 years or older

7. ECOG performance status ≤ 1

8. Resolution of all acute adverse events resulting from prior cancer therapies to NCI
CTCAE grade ≤ 1 or baseline

9. Adequate organ function

10. Willingness and ability to consent to participate in study

11. Willingness and ability to comply with scheduled visits, treatment plan, laboratory
tests, and other study procedures

12. Men who are sterile OR agree to use at least two forms of a reliable and highly
effective method of birth control and to not donate sperm and for at least 180 days
following last dose of TRC105 or sorafenib.

13. Woman of non-child bearing potential due to surgical sterilization confirmed by
medical history or menopause, OR woman of child bearing potential who test negative
for pregnancy at time of enrollment based on serum pregnancy test and agree to use at
least 2 forms of a reliable and highly effective method of birth control during the
study and for at least 180 days after stopping TRC105 or sorafenib.

Exclusion Criteria:

1. Prior anticancer systemic therapy

2. Current treatment on another therapeutic clinical trial

3. Prior radiation therapy within 28 days of starting the study treatment

4. No major surgical procedure or significant traumatic injury within 6 weeks prior to
study registration, and must have fully recovered from any such procedure.

5. Proteinuria

6. Uncontrolled chronic hypertension defined as systolic > 150 or diastolic > 90 despite
optimal therapy.

7. History of brain involvement with cancer, spinal cord compression, or carcinomatous
meningitis, or new evidence of brain or leptomeningeal disease.

8. Angina, MI, symptomatic congestive heart failure, cerebrovascular accident, transient
ischemic attack, arterial embolism, pulmonary embolism, PTCA or CABG within the past 6
months.

9. Active bleeding or pathologic condition that carries a high risk of bleeding. No
bleeding diathesis.

10. Thrombolytic use within 10 days prior to first day of study therapy

11. History of hemorrhage or hemoptysis (> ½ teaspoon bright red blood) within 3 months of
starting study treatment

12. Need for anticoagulation

13. History of liver transplant

14. History of bleeding esophageal varices in previous 6 months, which have not been
adequately managed with banding or sclerotherapy.

15. History of peptic ulcer disease within 3 months of treatment.

16. Known human immunodeficiency virus (HIV) or acquired immunodeficiency syndrome (AIDS)
related illness

17. Patients may not have received a strong CYP3A4 inducer within 12 days prior to
registration

18. Patients with known hypersensitivity to Chinese hamster ovary products or other
recombinant human, chimeric, or humanized antibodies.

19. Other severe acute or chronic medical or psychiatric condition or laboratory
abnormality

20. Ascites or pleural effusion requiring intervention or that required intervention
within the last month and has recurred

21. Pericardial effusion (except trace effusion identified by echocardiogram)