Study of Dalantercept and Axitinib in Patients With Advanced Renal Cell Carcinoma

Key Inclusion Criteria:

   - Histologically confirmed, advanced, predominantly clear cell renal cell carcinoma
   (RCC).

   - Part 1: Progression of disease following up to three lines of prior therapy, including
   at least one approved VEGF receptor tyrosine kinase inhibitor for RCC. Adjuvant
   therapy is permitted as one line of prior therapy.

   - Part 2: Progression of disease following one VEGF pathway inhibitor for RCC (e.g.
   sunitinib, pazopanib, sorafenib, bevacizumab, tivozanib, or cabozantinib) inclusive of
   adjuvant therapy if there was documented disease progression during treatment.
   Patients may have received one additional line of an approved mTOR kinase inhibitor
   (e.g. everolimus, temsirolimus). Prior exposure to investigational and/or approved
   anticancer immune therapies is permitted.

   - A minimum of 1 week since the last dose of prior therapy (a minimum of 4 weeks since
   anticancer immune therapy or bevacizumab +/- interferon).

   - Measurable disease that is evaluable by Response Evaluation Criteria in Solid Tumors
   (RECIST) v1.1.

   - Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1.

   - Life expectancy of at least 12 weeks.

   - Clinical laboratory values within acceptable ranges within 72 hours prior to study day
   1.

Key Exclusion Criteria:

   - Clinically significant organ/system disease unrelated to RCC that in the judgment of
   the investigator should preclude treatment with dalantercept or axitinib.

   - Clinically significant cardiovascular risk.

   - Known CNS metastases or leptomeningeal disease:

For Part 1, patients with CNS metastases treated with whole brain radiotherapy, gamma
knife, and/or surgery who are considered stable by CNS imaging and are not being treated
with corticosteroids 6 weeks prior to study day 1 may be enrolled.

For Part 2, patients with CNS metastases treated stereotactic radio-surgery (SRS), and/or
surgery who are considered stable by CNS imaging for at least 2 months prior to enrollment
and are not being treated with corticosteroids 6 weeks prior to study day 1 may be
enrolled.

   - Any active malignancy, other than RCC, for which chemotherapy or other anti-cancer
   therapy is indicated. Patients with adequately treated non-melanoma skin cancer, in
   situ cancer, or other cancer from which the subject has been disease-free for at least
   3 years will be permitted.

   - Any lesion invading or having encasement ≥ 180 degrees around the wall of a major
   blood vessel as assessed by computed tomography (CT) scan and/or magnetic resonance
   imaging (MRI).

   - Radiotherapy within 2 weeks prior to study day 1.

   - Lack of recovery from toxic effects of previous treatment for RCC ≤ grade 1 with the
   exception of alopecia, unless stabilized under adequate medical control.

   - Patients undergoing renal dialysis.

   - Major surgery within 4 weeks prior to study day 1 (patients must have recovered
   completely from any previous surgery prior to study day 1).

   - Any active infection requiring antibiotic therapy within 2 weeks of study day 1.

   - Anti-coagulation therapy. Aspirin, other anti-platelet agents, and low molecular
   weight heparin are permitted unless the investigator deems the patient is at a
   significant risk for bleeding.

   - Current use or anticipated inability to avoid potent CYP3A4/5 inhibitors or inducers
   (please refer to the Inlyta® [axitinib] prescribing information) during participation
   in the study.

   - Peripheral edema requiring medical intervention within 2 weeks prior to study day 1.

   - Bleeding diathesis including clinically significant platelet disorders or active
   hemoptysis (defined as bright red blood of ≥ 1/2 teaspoon [2.5 mL] in any 24 hour
   period) within 6 months prior to study day 1. For clinically significant epistaxis
   within 4 weeks prior to study day 1, no risk of further bleeding must be clearly
   documented.

   - Known history of hereditary hemorrhagic telangiectasia (HHT).

   - Known active hepatitis B virus (HBV) or hepatitis C virus (HCV) infections or positive
   human immunodeficiency virus (HIV) antibody results. Patients with sustained virologic
   response to HCV treatment or immunity to HBV from prior infection without cirrhosis
   may be included.

   - History of severe (defined as ≥ grade 3, using the National Cancer Institute Common
   Toxicity Criteria for Adverse Events, version 4.0 [NCI-CTCAE] v4 current active minor
   version) allergic or anaphylactic reaction or hypersensitivity to recombinant proteins
   or excipients (10 mM Tris buffered saline) in the investigational agent.

   - Any prior treatment with dalantercept or any other agent targeting ALK1 pathway.

   - Any prior treatment with axitinib.

   - A morbidity (per the prescribing information) that would require starting a patient at
   a reduced dose of axitinib.

   - Treatment with another investigational drug (with the exception of anticancer immune
   therapy) or device, or approved therapy for investigational use, within 5 times the
   half-life of the drug or within 3 weeks prior to study day 1 if the half life is not
   known.

   - Pregnant or lactating female patients.