Open-label, multicenter, dose titration and four-arm expansion trial to evaluate the safety,
tolerability, immunogenicity, and preliminary efficacy of W_pro1 cancer vaccine (W_pro1)
monotherapy or in combination with cemiplimab in patients with metastatic castration
resistant prostate cancer (mCRPC: Part 1 and Part 2 Arms 1A and 1B) and in patients with
high-risk, localized prostate cancer (LPC).
- W_pro1 consists of messenger ribonucleic acid (mRNA [or RNA]) targeting 5 antigens
expressed in de novo and metastatic prostate cancer that are separately complexed with
liposomes to form serum-stable RNA lipoplexes (RNA-LPX).
- The RNA molecules are immune-pharmacologically optimized for high stability,
translational efficiency and presentation on major histocompatibility complex (MHC)
class I and II molecules. The vaccine is intended for intravenous (IV) bolus injection.
- The RNA-LPX cancer vaccine induces activation of both the adaptive immune system
(vaccine antigen-specific CD8+/CD4+ T cell) as well as the innate immune system (TLR7
agonism of single-stranded RNA). The physiology of efficient induction, expansion and
differentiation of antigen-specific T cells is associated with programmed death
receptor-1 (PD-1) upregulation on these T cells. Thus, the cancer vaccine is expected to
have a synergistic mechanism of action with anti-PD-1.
- In summary, the mechanism of action of W_pro1 both in monotherapy and in combination
with anti-PD-1 immune checkpoint inhibitor cemiplimab, together with carefully selected
and refined clinical setting presents a unique opportunity for patients with different
stages of prostate cancer.
- Patients must be male and aged ≥18 years.
- Patients must have histologically confirmed prostate adenocarcinoma.
- Patients must have an Eastern Cooperative Oncology Group Performance Status (ECOG PS)
score of 0 or 1.
Specific key inclusion criteria for mCRPC patients (Part 1 and Part 2 Arms 1A and 1B):
- Patients must have histologically confirmed mCRPC and have progressed after at least 2
but no more than 3 lines of life-prolonging systemic therapy (e.g., abiraterone or
enzalutamide, docetaxel, cabazitaxel) or cannot tolerate any of these therapies. These
lines of therapy include life-prolonging therapies administered in the metastatic
- Prior surgical or chemical castration with a serum testosterone <1.7 nmol/L (50
ng/dL). If the method of castration is luteinizing hormone-releasing hormone analogue
(LHRHa), there must be a plan to maintain effective LHRHa therapy for the duration of
- Patients must have documented mCRPC progression within 6 months prior to screening
(assuming no subsequent change in treatments), as determined by the investigator.
- Patients must agree to provide an archival pre-treatment formalin-fixed,
paraffin-embedded tumor sample if available.
Specific key inclusion criteria for newly diagnosed LPC patients (Part 2 Arms 2 and 3):
- Treatment-naïve patients with LPC (i.e., N0, M0). According to risk levels of the
European Association of Urology Guidelines on Prostate Cancer (2018), and in line with
the U.S. National Comprehensive Cancer Network (NCCN 2020), patients must have at
least 1 of the following:
1. PSA >20 ng/mL or
2. Gleason Score >7 or
3. Localized stage ≥cT2c, N0, M0 according to tumor, node, metastasis
- Patients who intend to have and are suitable for a radical prostatectomy.
- Patients must agree to provide tumor sample(s) from pre-treatment diagnostic biopsy
and planned post-treatment surgery.
Main exclusion criteria for all patients:
- Patients with uncontrolled intercurrent illness.
- Patients with a known history or current malignancy other than the inclusion
diagnosis. Note: Exceptions are patients with malignancies with a negligible risk of
metastasis or death, that have been adequately treated, such as non-invasive basal
cell or non-invasive squamous cell skin carcinoma, non-invasive, superficial bladder
cancer, and any cancer with a complete response (CR) that lasted more than 2 years may
- Patients who have had major surgery (e.g., requiring general anesthesia) within 4
weeks before screening, or have not fully recovered from surgery, or have a surgery
planned during the time of trial participation, except for the radical prostatectomy
planned for patients in Part 2 Arms 2 and 3.
- Patients who have a known history of any of the following (testing not required):
1. Human immunodeficiency virus (HIV) 1 or 2
2. Hepatitis B (carrier or active infection)
3. Hepatitis C (unless considered cured 5 years post curative anti-viral therapy)
- Patients who have received or currently receive the following therapy/treatment:
1. Chronic systemic immunosuppressive corticosteroid treatment (prednisone >5 mg
daily orally [PO] or IV, or equivalent) during the trial. Note: Replacement
therapy (e.g., physiologic corticosteroid replacement therapy for adrenal or
pituitary insufficiency) is not considered a form of systemic treatment and is
2. Prior treatment with other immune modulating agents that was (a) within fewer
than 4 weeks (28 days) or 5 half-lives (whichever is longer) prior to the first
dose of cemiplimab, or (b) associated with immune-mediated AEs that were Grade ≥1
within 90 days prior to the first dose of cemiplimab, or (c) associated with
toxicity that resulted in discontinuation of the immune-modulating agent.
3. Prior treatment with other immune modulating agents for any non-cancer disease
within 4 weeks or 5 half-lives of the agent (whichever is longer) before the
first dose of IMP.
4. Prior treatment with live-attenuated vaccines within 4 weeks before the first
dose of IMP and during treatment with IMP.
5. Prior treatment with an investigational drug (including investigational vaccines)
within 4 weeks or 5 half-lives of the agent (whichever is longer) before the
planned first dose of IMP.
6. Therapeutic PO or IV antibiotics within 14 days prior to enrollment. Note:
Patients receiving prophylactic antibiotics (e.g., for prevention of a urinary
tract infection or chronic obstructive pulmonary disease) may be enrolled.
7. Concurrent use of herbal products that may decrease PSA levels (e.g., saw
Specific key exclusion criteria for mCRPC Patients (Part 1 and Part 2 Arms 1A and 1B):
Excluded medical conditions
- Patients with toxicities from previous anti-cancer therapies that have not resolved to
baseline levels or to Grade ≤1 according to National Cancer Institute (NCI) CTCAE v5.0
with the exception of alopecia, anorexia, vitiligo, fatigue, hyperthyroidism,
hypothyroidism, and peripheral neuropathy. Anorexia, hyperthyroidism, hypothyroidism,
and peripheral neuropathy must have recovered to Grade ≤2.
- Patients with clinically active brain metastases.
1. Patients with a history of symptomatic metastatic brain or meningeal tumors may
be included, if the end of definitive therapy is >3 months before the first dose
of W_pro1 and the patients have no clinical or radiological evidence of tumor
2. Patients with brain metastases must not be undergoing acute or chronic
corticosteroid therapy or steroid taper.
3. Patients with central nervous system symptoms should undergo a computed
tomography (CT) scan or magnetic resonance imaging (MRI) of the brain to exclude
new or progressive brain metastases. Spinal cord metastasis is acceptable.
However, patients with spinal cord compression should be excluded.
Excluded prior or concomitant anti-cancer therapies
- Patients who have received or currently receive the following anti-cancer
1. Prior radiation therapy with curative intent within 14 days before the first dose
of IMP. Note: Palliative radiotherapy is allowed.
2. Prior treatment with an anti-cancer agent (within 4 weeks or for systemic
therapies after at least 5 half-lives of the drug [whichever is longer] before
the first dose of IMP). Note: Prior treatment with bone resorptive therapy, such
as bisphosphonates (e.g., pamidronate, zoledronic acid, etc.) and denosumab, is
allowed assuming that the patients have been on stable doses for ≥4 weeks prior
to first dose of trial treatment.
3. Prior treatment with anti-cancer immunomodulating agents, such as blockers of
programmed death receptor-1 PD-1, programmed cell death 1 ligand 1 (PD-L1), tumor
necrosis factor receptor superfamily member 9 (TNRSF9, 4-1BB, CD137), OX-40,
therapeutic vaccines, cytokine treatments, or any investigational agent within 4
weeks or 5 half-lives (whichever is longer) before the first dose of IMP.