Extension Study of UC-961 (Cirmtuzumab) for Patients With Chronic Lymphocytic Leukemia Treated Previously With UC-961

This is an open-label extension study to determine the safety and tolerability of cirmtuzumab
given to participants who enrolled and completed the initial phase 1 trial in CLL without a
dose-limiting toxicity.

UC-961 is administered by intravenous infusion every 14 days for 4 doses, then every 28 days
for 4 doses, after which responses will be assessed. Patients with an objective response
(meeting working group criteria for partial response or complete response) will continue at
the same dose and schema. Patients with stable disease or progressive disease are eligible to
increase the dose of UC-961 for another 6-month course.

Duration of UC-961 administration is until disease progression, treatment intolerance, or
lack of clinical benefit.

Inclusion Criteria:

- Clinical and phenotypic verification of B cell CLL and measurable disease.
Immunophenotyping of the leukemic cells (blood or marrow) must demonstrate a
monoclonal (or light chain positive) B cell population with immunophenotype consistent
with CLL (e.g., co-expressing CD19 and CD5).

- Recovered from toxic effects attributed to UC-961 to grade 1 levels, or baseline.

- Must have measurable disease, including one of the following:

- absolute lymphocyte count greater than 5000/uL

- lymphadenopathy greater than 1.5 cm in longest dimension

- splenomegaly

- bone marrow biopsy with residual CLL cells, or resultant bone marrow dysfunction

- Women of childbearing potential must agree not to become pregnant for the duration of
the study. Both men and women must agree to use a barrier method of contraception for
the duration of the study and until 10 weeks after the final dose of UC-961.

- Subjects must have an ECOG performance status of 0-2.

- Adequate hematologic function

- Adequate renal function

- Adequate hepatic function

- Adequate coagulation tests

Exclusion Criteria:

- Pregnant or breast-feeding women

- May have had intervening therapy since completion of initial UC-961 dosing, but
excluding the following:

- Within 7 days of UC-961 restart, or 5 half-lives (if known), whichever is
shorter: small molecule tyrosine kinase inhibitor (eg: ibrutinib, idelalisib,
AVL-292, IPI-145);

- Within 28 days of UC-961 restart: chemotherapy (e.g., purine analogues,
alkylating agents), corticosteroids, radiation therapy, or participation in any
other investigational drug treatment (besides UC-961);

- Within 56 days of UC-961 restart: previous UC-961 dosing;

- Within 56 days of UC-961 restart: monoclonal antibody therapy directed against
CLL (e.g., rituximab, ofatumumab, obinutuzumab, alemtuzumab).

- Current infection requiring parenteral antibiotics.

- Active infection with HIV, HBV, or HCV.

- Concurrent malignancy or prior malignancy within the previous 3 years (other than
completely resected carcinoma in situ, prostate cancer, or localized non-melanoma skin
cancer).

- Known central nervous system (CNS) involvement by malignancy.

- Untreated autoimmunity such as autoimmune hemolytic anemia, or immune
thrombocytopenia.

- Uncompensated hypothyroidism (defined as TSH greater than 2x upper limit of normal not
treated with replacement hormone).

- Presence of more than 55% pro-lymphocytes in peripheral blood. Patients with Richter's
transformation are not excluded.

- Insufficient recovery from surgical-related trauma or wound healing.

- Impaired cardiac function including any of the following:

- Myocardial infarction within 6 months of starting study drug;

- A past medical history of clinically significant ECG abnormalities;

- Other clinically significant heart disease (e.g. uncontrolled congestive heart
failure, uncontrolled hypertension, history of labile hypertension, or history of
poor compliance with an antihypertensive regimen).