Phase II Study of KW2871 Combined With High Dose Interferon-α2b in Patients With Metastatic Melanoma

Eligible patients were sequentially enrolled into dose-escalating cohorts to receive KW2871
intravenously (IV) once every 2 weeks starting on Day 3 of Week 1 at the following doses: 5
mg/m^2 in Cohort 1, 10 mg/m^2 in Cohort 2, and 20 mg/m^2 in Cohort 3. HDI was administered
concurrently at a dose of 20 million units (MU)/m^2 IV once daily (QD) for 5 consecutive days
per week for 4 weeks (induction phase), followed by 10 MU/m^2 administered subcutaneously
(SC) 3 times per week (maintenance phase). Patients received KW2871 and HDI combination
therapy until disease progression requiring treatment intervention that would have interfered
with the interpretation of the study results.

Initially, 3 patients were enrolled within a cohort and evaluated for dose-limiting toxicity
(DLT) and regimen-limiting toxicity (RLT) for the first 8 weeks of study treatment. If 1 of 3
patients experienced an RLT, the cohort was expanded to 6 patients. Escalation to the next
higher dose cohort proceeded if the RLT rate was <33% (0/3 or 1/6 patients) in a given
cohort. The combination treatment was considered safe if ≤ 20% patients experienced RLT.

DLT was defined as any adverse event (AE) that required reduction of the HDI dose or
discontinuation of KW2871. RLT was defined as an HDI-related DLT that required more than 2
dose reductions of HDI during the induction phase or the first 4 weeks of the maintenance
phase, or any KW2871- or regimen-related DLT.

Inclusion Criteria:

1. Age ≥ 18 years of age.

2. Histologically proven metastatic cutaneous, mucosal, or unknown primary melanoma.

3. Measurable disease using Response Evaluation Criteria in Solid Tumors (RECIST).

4. Ambulatory (Eastern Cooperative Oncology Group [ECOG] performance status 0 or 1) or
expected survival ≥ 4 months.

5. Within the last 2 weeks prior to study day 1, the following laboratory parameters
within the ranges specified:

- Hemoglobin: ≥ 9 g/dL

- Platelets: ≥ 100 x 10^9/L

- Neutrophils: ≥ 1.5 x 10^9/L

- International normalized ratio: ≤ 2.0 (≤ 3.0 if on warfarin therapy)

- Serum creatinine: ≤ 1.5 x upper limit of normal (ULN)

- Serum total bilirubin: ≤ 1.5 x ULN

- Aspartate aminotransferase/alanine aminotransferase: ≤ 2.5 x ULN

6. Able and willing to give valid written informed consent.

Exclusion Criteria:

1. Other malignancy within 3 years prior to study entry for which the patient received
active treatment, except for treated melanoma or non-melanoma skin cancer, cervical
cancer, and breast carcinoma in situ.

2. Mental impairment that may have compromised the ability to give informed consent and
comply with the study requirements.

3. Participation in any other clinical trial involving chemotherapy, radiotherapy, or
other immunotherapy within 4 weeks prior to study enrollment.

4. Prior exposure to anti-GD3 antibodies.

5. Pregnancy or breastfeeding.

6. Women of childbearing potential who refused or were unable to use effective means of
contraception.

7. Active autoimmune or other disorders that required systemic treatment with
immunomodulatory or immunosuppressant medications (i.e., corticosteroids,
cyclophosphamide, methotrexate, other biologics). Corticosteroids at substitution
doses were allowed.

8. Metastatic brain disease was allowed provided that appropriate treatment had been
administered (surgery or irradiation) and 2-month follow-up by brain magnetic
resonance imaging (MRI) showed disease control (stability or regression).

9. Autoimmune-related hypothyroidism and vitiligo-like depigmentation were allowed
provided the patient was medically stable with treatment (thyroid-hormone replacement
or observation).

10. Serious medical illness, such as cardiovascular disease (uncontrolled congestive heart
failure or hypertension, active ischemic disease of the heart [angina], recent [<3
months] myocardial infarction, severe cardiac arrhythmia), bleeding disorders,
obstructive or restrictive pulmonary diseases, active systemic infections requiring
antibiotics, serious intercurrent illness requiring hospitalization, inflammatory
bowel disorders, or significant psychiatric disease, which in the opinion of the
principal investigator would have prevented adequate informed consent or rendered
study treatment unsafe or contraindicated.

11. Patients with clinical suspicion of human immunodeficiency virus (HIV) or hepatitis
underwent the following viral tests: patients with HIV must have had negative
antibodies; patients with hepatitis B virus must have had negative antigens; patients
with hepatitis C virus must have had a negative test for serum antibodies. If any of
the tests were positive, patients were excluded from the study.