ADXS31-142 Alone and in Combination With Pembrolizumab (MK-3475) in Patients With Prostate Cancer - KEYNOTE-046

Part A of the study will be an open-label, Phase 1, multicenter, non-randomized,
dose-determining trial of ADX31-142 monotherapy in subjects with metastatic
castration-resistant prostate cancer (mCRPC). The dose determining phase is intended to
select a recommended Phase 2 dose (RP2D) for Part B.

Part B of the study will be an open-label, Phase 1-2, multicenter, non-randomized
dose-determining trial of ADXS31-142 in combination with pembrolizumab (MK-3475) in subjects
with mCRPC. Part B will consist of a dose-determination phase followed by an expansion cohort
phase. The dose-determining phase is intended to select a RP2D for the combination.

Dose escalation/de-escalation for this study will be explored by applying the mTPI design.

Inclusion Criteria:

1. Be willing and able to provide written informed consent for the trial.

2. Be 18 years of age or older on day of signing informed consent.

3. Have progressive metastatic castration resistant prostate cancer, on androgen
deprivation therapy, based on as least one of the following criteria:

1. PSA progression defined as 25% increase over baseline value with an increase in
the absolute value of at least 2 ng/mL that is confirmed by another PSA level
with a minimum of a 1 week interval with a minimum PSA of 2 ng/ml.

2. Progression of bi-dimensionally measurable soft tissue (nodal metastasis)
assessed within 1 month prior to registration by a CT scan or MRI of the abdomen
and pelvis.

3. Progression of bone disease (evaluable disease) (new bone lesion(s)) by bone
scan.

4. Has discontinued antiandrogens (bicalutamide, nilutamide) >6 weeks and enzalutamide >4
weeks prior to Day 1 of trial treatment

5. Have a performance status of 0 or 1 on the ECOG Performance Scale.

Exclusion Criteria:

1. Received more than 3 prior systemic treatment regimens with chemotherapy , hormonal,
or immunotherapy in the metastatic setting or received more than 1 prior
chemotherapeutic regimen in the metastatic setting

2. Has a diagnosis of immunodeficiency or is receiving any systemic steroid therapy or
any other form of immunosuppressive therapy within 7 days prior to Day 1 of trial
treatment. The use of physiologic doses of corticosteroids may be approved after
consultation with the Sponsor.

3. Has had a prior monoclonal antibody within 4 weeks prior to study Day 1 or who has not
recovered (i.e., ≤Grade 1 or at baseline) from adverse events due to agents
administered more than 4 weeks earlier.

4. Has had prior chemotherapy, targeted small molecule therapy, or radiation therapy
within 2 weeks prior to study Day 1 or who has not recovered (i.e., ≤Grade 1 or at
baseline) from adverse events due to a previously administered agent.

5. Has received prior therapy with an anti-PD-1, anti-PD-L1, or anti-PD-L2 agent or if
the patient has previously participated in a Merck MK-3475 clinical trial.

6. Has a contraindication to administration of ampicillin or trimethoprim/
sulfamethoxazole.

7. Has implanted medical device(s) that pose a high risk for colonization and/or cannot
be easily removed (e.g., prosthetic joints, artificial heart valves, pacemakers,
orthopedic screw(s), metal plate(s), bone graft(s), or other exogenous implant(s)).
NOTE: More common devices and prosthetics which include arterial and venous stents,
dental and breast implants, and venous access devices (e.g., Port-a-Cath or Mediport)
are permitted. Sponsor must be contacted prior to consenting any subject who has any
other device and/or implant.