Detection of ARv7 in the Plasma of Men With Advanced Metastatic Castrate Resistant Prostate Cancer (MCRP)

Primary Objective

-Demonstrate detection of ARv7 splice variant transcripts from exosomes in the circulation of
MCRPC patients pre and post treatment with selective Androgen pathway inhibitors (i.e.
abiraterone and enzalutamide)

Secondary and Exploratory Objectives

- Correlate ARv7 status with PSA response (>/=50% decline in PSA level from baseline,
maintained for >/=4 weeks) at any time after the initiation of therapy.

- Comparison of median progression free survival (PFS) and overall survival (OS).

- Determine additional molecular lesions in exoRNA and cfDNA in MCRPC patients
post-treatment with androgen pathway inhibitors.

- Correlate other AR-variants (non ARv7) with clinical outcomes including PSA response.

Inclusion Criteria:

1. Participants must have histologically confirmed diagnosis of adenocarcinoma of the
prostate.

2. Clinical or radiographic evidence of metastatic disease.

3. Planned therapy with either enzalutamide or abiraterone acetate within the coming 6
weeks.

4. Evidence of disease progression on or following most recent therapy as evidenced by
the following:

- Radiographic evidence of disease progression as defined by one or more new bone
scan lesions.

- Growth of soft tissue / visceral metastases to greater than one centimeter in
longest diameter.

- Progressive disease despite 'castration levels' of serum testosterone (<50ng/dL
with continued androgen deprivation therapy.

5. At least two of the following high risk features during screening for rapid disease
progression:

- Anemia with a hemoglobin <12.0 g/dL

- Elevated alkaline phosphatase

- High lactate dehydrogenase (LDH)

- Presence of visceral metastasis on imaging

- Presence of clinically significant pain requiring opioid analgesics.

- PSA doubling time under 3 months on most recent therapy

- PSA values obtained 2 or more weeks apart, with last value being 2.0ng/mL or
higher.

6. Ability to understand and willingness to sign a written informed consent document.

Exclusion Criteria:

1. Receiving or intend to receive concurrent chemotherapy

2. Hepatitis (all types) in patient's medical record

3. HIV documented in patient's medical record

4. History of intercurrent or past medical history or psychiatric illness that would make
participation in a blood drawing protocol difficult or not feasible.