Recruiting

Phase 1

Phase 2

REGN5678A Pilot Presurgical Trial of REGN5678 (Anti-PSMA x CD28) in Patients With High-risk, Localized Prostate Cancer Followed by Radical Prostatectomy

Sponsor:

M.D. Anderson Cancer Center

Code:

NCT06085664

Conditions

Prostate Cancer

Radical Prostatectomy

Eligibility Criteria

Sex: Male

Age: 18+

Healthy Volunteers: Not accepted

Interventions

REGN5678

Piflufolastat F18

Study Details

Brief summary:

To learn about the safety and effects of a drug called REGN5678 when it is given to patients with high-risk prostate cancer.

Conditions

Prostate Cancer

Radical Prostatectomy

Study ID

NCT06085664

Start date

Dec 4, 2023

Status verified date

Aug, 2026

Completion date

Jun 30, 2028

Anticipated

Primary completion date

Jun 30, 2028

Anticipated

Eligibility Criteria

Sex: Male

Age: 18+

Healthy Volunteers: Not accepted

Inclusion Criteria:

Men ≥ 18 years of age
Histologically documented Gleason 8 or greater prostatic adenocarcinoma in at least 3 biopsy cores and at least 8 mm of disease on a single core of Gleason 8 or greater. Prostate biopsy within 3 months of screening is allowed for entry requirements. Prostate biopsy must be reviewed at MD Anderson Cancer Center. Patients with small cell, neuroendocrine, or transitional cell carcinomas or mixed histologies are not eligible
Eastern Cooperative Oncology Group (ECOG) performance status (PS) grade of 0 or 1
No evidence of metastatic disease as documented by technetium-99m (99mTc) bone scan and by computed tomography (CT) or magnetic resonance imaging (MRI) scans. Imaging may be obtained up to 60 days prior to enrollment
Localized or locally advanced disease deemed by the surgeon to be resectable. Patients must be appropriate candidates for radical prostatectomy plus pelvic lymph node dissection
No prior treatment for prostate cancer including prior surgery (excluding transurethral resection of the prostate \[TURP\]), cryoablation, pelvic lymph node dissection, radiation therapy, hormonal therapy or chemotherapy
Hemoglobin ≥ 11 g/dL
Absolute neutrophil count ≥ 1.5 x 10\^9/L
Platelet count ≥ 100 x 10\^9/L
Serum creatinine ≤ 1.5 x upper limit of normal (ULN) or estimated glomerular filtration rate > 50 mL/min/1.73 m\^2. A 24-hour urine creatinine collection may substitute for the calculated creatinine clearance to meet eligibility criteria
Total bilirubin ≤ 1.5 x ULN

NOTES: Patients with Gilbert's syndrome do not need to meet total bilirubin requirements provided their total bilirubin is not greater than their historical level. Gilbert's syndrome must be documented appropriately as past medical history
Aspartate aminotransferase (AST) ≤ 2.5 x ULN
Alanine aminotransferase (ALT) ≤ 2.5 x ULN
Alkaline phosphatase (ALP) ≤ 2.5 x ULN
Consent to MD Anderson laboratory protocol PA13-0291
Willing and able to comply with clinic visits and study-related procedures
Provide informed consent signed by study patient
To avoid risk of drug exposure through the ejaculate (even men with vasectomies), subjects must use a condom during sexual activity while on study drug and for 3 months following the last dose of study drug. If the subject is engaged in sexual activity with a woman of childbearing potential, a condom is required along with another effective contraceptive method consistent with local regulations regarding the use of birth control methods for subjects participating in clinical studies and their partners. Donation of sperm is not allowed while on study drug and for 3 months following the last dose of study drug

Exclusion Criteria:

Prior hormone therapy for prostate cancer including orchiectomy, antiandrogens, ketoconazole, or estrogens (5-alpha reductase inhibitors allowed), or luteinizing hormone-releasing hormone (LHRH) agonists/antagonists
Currently enrolled in another interventional study
Concurrent treatment with systemic corticosteroids (prednisone dose > 10 mg per day or equivalent) or other immunosuppressive drugs < 14 days prior to treatment initiation. Steroids that are topical, inhaled, nasal (spray), or ophthalmic solution are permitted
History of or known or suspected autoimmune disease (exception\[s\]: subjects with vitiligo, resolved childhood atopic dermatitis, hypothyroidism, or hyperthyroidism that is clinically euthyroid at screening are allowed)
Known evidence of an active infection requiring systemic therapy such as human immunodeficiency virus (HIV), active hepatitis, or fungal infection. Patients with known HIV infection which is well-controlled (undetectable viral load by HIV ribonuclecid acid \[RNA\] polymerase chain reaction \[PCR\]) and CD4 counts greater than 350 are permitted to participate
History of clinically significant cardiovascular disease including, but not limited to:

Myocardial infarction or unstable angina ≤ 6 months prior to treatment initiation
Clinically significant cardiac arrhythmia
Deep vein thrombosis, pulmonary embolism, stroke ≤ 6 months prior to treatment initiation
Congestive heart failure (New York Heart Association class III-IV)
Pericarditis/clinically significant pericardial effusion
Myocarditis
Endocarditis
History of major implant(s) or device(s), including but not limited to:

Prosthetic heart valve(s)
Artificial joints and prosthetics placed ≤ 12 months prior to treatment initiation
Current or prior history of infection or other clinically significant adverse event associated with an exogenous implant or device that cannot be removed
Other prior malignancy (exceptions: adequately treated basal cell or squamous cell skin cancer, superficial bladder cancer, or any other cancer in situ currently in complete remission) ≤ 2 years prior to enrollment
Has received major surgery within 14 days of first administration of study drug
Encephalitis, meningitis, neurodegenerative disease (with the exception of mild dementia that does not interfere with activities of daily living \[ADLs\]) or uncontrolled seizures in the year prior to first dose of study therapy
Known history of, or any evidence of interstitial lung disease, or active, non-infectious pneumonitis (past 5 years)
Receipt of a live vaccine within 4 weeks of planned start of study medication
Prior allogeneic stem cell transplantation or recipients of organ transplants at any time, or autologous stem cell transplantation within 12 weeks of the start of study treatment
Any medical, psychological or social condition that in the opinion of the investigator, would preclude participation in this study

Study Design

Enrollment

42 participants

Anticipated

Intervention Model

Sequential

Primary purpose

Treatment

Interventions and Outcome Measures

Arms

experimental: REGN5678 (anti-PSMAxCD28)

Participants will receive REGN5678 by vein over about 2 hours the first time you receive it.

Participants will be admitted to the hospital, where participants will be monitored for side effects. Other doses may be given over 30-90 minutes depending on how you handle the dose.

Participants will receive REGN5678 weekly for 6 weeks.

Interventions

REGN5678

Given by IV (vein)

Piflufolastat F18

Given by IV (vein)

Primary outcome measure

Incidence of Adverse Events, Graded According to National Cancer Institute Common Terminology Criteria for Adverse Events (NCI CTCAE) Version (v) 5.0 [ Time Frame: Through study completion; an average of 1 year ]

Central Contacts and Locations

Central contacts

Sumit Subudhi, MD, PHD

(713) 792-2830 sksubudhi@mdanderson.org

Sumit Sumit, MD, PHD

(713) 792-2830 sksubudhi@mdanderson.org

Locations

M D Anderson Cancer Center

Recruiting

Houston, Texas, United States, 77030

Contacts

Sumit K. Subudhi, MD, PHD

713-792-2830 sksubudhi@mdanderson.org

Principal Investigator:

Sumit K. Subudhi, MD, PHD

More Information

Sponsor

M.D. Anderson Cancer Center

Last update posted

Aug 25, 2026

Last verified

Aug, 2026

Trial information was received from ClinicalTrials.gov and was last updated on 2026-09-09. This information was provided to ClinicalTrials.gov by M.D. Anderson Cancer Center on 2026-08-25.