Metastatic Castration-Resistant Prostate Cancer (mCRPC)Phase 1/2NCT06126731
Combination Study of Antibiotics With Enzalutamide (PROMIZE)
A Phase 1/2 study testing Enzalutamide 40mg, Amoxicillin 500mg and Metronidazole 400mg in people with Metastatic Castration-Resistant Prostate Cancer (mCRPC), run by Institute of Cancer Research, United Kingdom at 2 sites in 2 countries.
Trial summary
PROMIZE is an open-label, multi-centre, single-arm, Phase I/II clinical trial, evaluating the safety, tolerability and anti-tumuor efficacy of an antibiotic combination and enzalutamide in patients with metastatic castration-resistant prostate cancer (mCRPC). Read more about this study
- Who is it for?
- Ages 18 years and older, men only
- Conditions the study is for
- Metastatic Castration-Resistant Prostate Cancer (mCRPC)
- What is being tested?
- Enzalutamide 40mg, Amoxicillin 500mg and Metronidazole 400mg
- Type of treatment
- Pill or oral medicine
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 39 participants
- Where
- 2 sitesin 2 countries
- Study dates
- 2 Nov 2023to 30 Jun 2027
- Phase
- Phase 1/2
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- Men only
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Histologically or cytologically proven metastatic castration-resistant prostate cancer or adenocarcinoma refractory to conventional treatment, or for which no conventional therapy exists or is declined by the patient.
- Documented prostate cancer progression as assessed by the investigator with RECIST (v1.1) and PCWG3 criteria with at least one of the following criteria:
- Progression of soft tissue/visceral disease by RECIST (v1.1) and/or,
- Progression of bone disease by PCWG3 bone scan criteria and/or,
- Progression of PSA by PCWG3 PSA criteria and/or
- Clinical progression with worsening pain and need for palliative radiotherapy for bone metastases.
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- Phase I: Patients that have progressed after at least 12 weeks of treatment with a NAAT within the previous 6 months Phase II: Patients that have progressed after at least 12 weeks of treatment with a NAAT within the previous 6 months (for combination treatment) or more than 6 months prior to trial entry (for enzalutamide alone resistance run-in).
- Previously progressed on at least one line of taxane chemotherapy (or not fit or not willing to receive a taxane).
- Ongoing androgen deprivation maintaining serum testosterone of less than 50 ng/dL (less than 2.0 nM) is mandatory.
- Life expectancy of at least 12-weeks.
- Able to swallow tablets.
- Archival tumour tissue must be available for analyses.
- Willing to have pre- and post-treatment biopsies if biopsy is feasible.
- World Health Organisation (WHO) performance status of 0-2 (Appendix 1).
- Haematological and biochemical indices within the ranges shown below. These measurements must be performed within one week (Day -7 to Day 1) prior to the patient's first dose of IMP.
- Haemoglobin (Hb): ≥ 9.0 g/dL
- Absolute neutrophil count: ≥ 1.5 x 109/L
- Platelet count: ≥ 75 x 109/L
- Serum bilirubin: ≤ 1.5 x upper limit of normal (ULN)
- Alanine aminotransferase (ALT): ≤ 2.5 x (ULN) unless raised due to tumour in which case up to 5 x ULN is permissible
- Aspartate aminotransferase (AST): ≤ 2.5 x (ULN) unless raised due to tumour in which case up to 5 x ULN is permissible
- Serum creatinine / calculated creatinine clearance: ≤ 1.5 x upper limit of normal (ULN) / GFR ≥ 50 mL/min (uncorrected value)
- Serum albumin: >25 g/L
- 18 years or over
- Written (signed and dated) informed consent and be capable of co-operating with treatment and follow-up
- Willing and able to comply with the study requirement including the collection of blood, fresh tumour biopsy, urine, rectal swab and stool samples.
Who cannot join
- Surgery, radiotherapy, chemotherapy, or other anti-cancer therapy within 4-weeks prior to trial entry into the study (6 weeks for bicalutamide). The use of bisphosphonates or RANK ligand inhibitors in patients with known osteopenia or osteoporosis or bone metastases is permitted. Prior antiandrogenic treatment exclusions as follows:
- Patients receiving enzalutamide immediately preceding the trial will be able to continue on enzalutamide without washout.
- Prior flutamide treatment during previous 4-weeks. N.B. Patients whose PSA did not decline in response to antiandrogens given as a second line or later intervention will only require a 14-day washout;
- Prior bicalutamide (Casodex) and nilutimide (Nilandron) treatment during previous 6-weeks;
- Prior progesterone, medroxyprogesterone, progestins, cyproterone acetate, tamoxifen, and 5-alpha reductase inhibitors during previous 2-weeks (14-days).
- Ongoing toxic manifestations of previous treatments. Exceptions to this are alopecia or certain Grade 1 toxicities, which in the opinion of the Investigator and the DDU should not exclude the patient.
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- Previous treatment with any systemic antibiotic within 12 weeks of study entry.
- Known hypersensitivity reaction or intolerance to any penicillin, amoxicillin, metronidazole, vancomycin, ciprofloxacin or enzalutamide.
- History of tendon disorder secondary to quinolones
- Use of drugs that are listed in the prohibited concomitant medications section including strong inducers and inhibitors of CYP450 (please refer to http://medicine.iupui.edu/clinpharm/ddis/table.aspx). Seville orange or grapefruit products and any herbal medications should be avoided for 4 weeks prior to starting trial treatment.
- Concurrent treatment with prohibited medications which include medications that causes ototoxicity, neurotoxicity, and nephrotoxicity.
- Known or suspected leptomeningeal metastases or untreated brain metastasis. Patients with brain metastases that have been treated and have been shown to be radiologically stable for more than 6 months may be considered for the trial.
- History of stroke, epilepsy or current excessive alcohol intake. History of clinically significant hearing loss including but not limited to congenital hearing loss, need for hearing aids, ongoing acute or chronic ear infection, history of tympanic membrane perforation, tinnitus, vertigo, Meniere disease, cerebrovascular ischemia.
- History of clinically significant hearing loss including but not limited to congenital hearing loss, need for hearing aids, ongoing acute or chronic ear infection, history of tympanic membrane perforation, tinnitus, vertigo, Meniere disease, cerebrovascular ischemia.
- Patients with partners of child-bearing potential (unless they agree to use a barrier method of contraception [condom plus spermicide] or to sexual abstinence effective from the first administration of any of the investigational agents, throughout the trial and for 6 months afterwards. Patients with partners of child-bearing potential must also be willing to ensure that their partner uses an effective method of contraception for the same duration for example, hormonal contraception, intrauterine device, diaphragm with spermicidal gel or sexual abstinence). Patients with pregnant or lactating partners must be advised to use barrier method contraception (for example, condom plus spermicidal gel) to prevent exposure of the foetus or neonate.
- NB. Abstinence is only considered to be an acceptable method of contraception when this is in line with the preferred and usual lifestyle of the subject. Periodic abstinence (e.g., calendar, ovulation, symptothermal, post-ovulation methods) and withdrawal are not acceptable methods of contraception
- Any condition that would increase enteral absorption in the opinion of the investigator, including but not limited to malabsorption syndromes, impaired GI motility, chronic pancreatitis, partial or complete gastric and/or bowel resections, history of clinically significant gastrointestinal bleeding in the last 6 months, history of mesenteric ischemia or bowel obstruction, chronic diarrhoea (≥Grade 2), inflammatory bowel disease (Crohn's disease, ulcerative colitis).
- At high medical risk because of non-malignant systemic disease including active uncontrolled infection.
- Clinically significant history of liver disease consistent with Child-Pugh Class B or C, including viral or other hepatitis, current alcohol abuse, or cirrhosis.
- Known to be serologically positive for hepatitis B, hepatitis C or human immunodeficiency virus (HIV).
- Any of the following cardiac criteria:
- Clinically important abnormalities including rhythm, conduction or ECG changes (left bundle branch block, third degree heart block).
- Factors predisposing to QT prolongation including congenital long QT syndrome; family history of prolonged QT syndrome, unexplained sudden death (under 40); concomitant medications known to prolong QT interval.
- Concurrent congestive heart failure, prior history of class III/ IV cardiac disease (New York Heart Association [NYHA] - refer to Appendix 5), prior history of cardiac ischaemia or prior history of cardiac arrhythmia.
- QTcF (corrected using Fredericia formula) of ≥460 ms.
- Prior bone marrow transplant or have had extensive radiotherapy to greater than 25% of bone marrow within eight weeks.
- Active or uncontrolled autoimmune disease requiring corticosteroid therapy or other forms of systemic immunosuppression.
- Patient is a participant or plans to participate in another interventional clinical trial, whilst taking part in this study. Participation in an observational trial would be acceptable.
- Any other condition which in the Investigator's opinion would not make the patient a good candidate for the clinical trial.
- Malignancy other than prostate cancer within 3-years of trial entry with the exception of adequately treated basal cell carcinoma. Cancer survivors, who have undergone potentially curative therapy for a prior malignancy must have no evidence of that disease for at least-3 years and be deemed at negligible risk for recurrence, are deemed eligible.
- Symptoms of COVID-19 and/or current documented COVID-19 infection.
Trial locations and contacts
2 sites in 2 countries. Contact the study team or a site near you to ask about taking part.
2 sites in 2 countries
Switzerland1 site, 1 recruiting
- Recruiting
Oncolgy Institute of Southern Switzerland (IOSI)
Bellinzona
Ilaria Colombo, Ilaria.colombo@eoc.ch
United Kingdom1 site, 1 recruiting
- Recruiting
The Royal Marsden NHS Foundation Trust
Sutton, SM2 5PT
Johann S De Bono, MD, 020 8722 4028, johann.debono@icr.ac.uk
About this study
Official title: PROMIZE: A Phase I/II Trial to Assess the Safety, Tolerability and Preliminary Anti-tumour Activity of Oral Combination Antibiotic Therapy to Modulate the Microbiome in Combination With Enzalutamide With Metastatic Castration Resistant Prostate Cancer (mCRPC).
PROMIZE is an open-label, multi-centre, single-arm, Phase I/II clinical trial, evaluating the safety, tolerability and anti-tumuor efficacy of an antibiotic combination and enzalutamide in patients with metastatic castration-resistant prostate cancer (mCRPC).
Read the detailed description
Patients with histologically confirmed metastatic castration-resistant adenocarcinoma of the prostate refractory to conventional therapy (or for which no conventional therapy exists or is declined by the patient), that have progressed after at least 1 line of taxane based chemotherapy (or not fit or not willing to receive a taxane) and a NAAT are eligible for the study. The Phase I will evaluate the safety and tolerability of the combination of amoxicillin plus metronidazole (2 weeks) followed by ciprofloxacin plus vancomycin (2 weeks) administered for 2 cycles (i.e., 8 weeks) in addition to enzalutamide (160 mg daily). Enzalutamide will continue beyond the completion of the antibiotic combination until disease progression, intolerance, or withdrawal from the study. The DLT period is 4 weeks and commences at the time of combination treatment with antibiotics plus enzalutamide. Each cycle of treatment will be 4 weeks in length.
The design permits the safety monitoring of DLT regularly throughout the 2 phases. During the Phase I study, if 2 or more patients experience a DLT out of up to 6 patients, the schedule will be deemed intolerable, and a decision will be made by the SRC to modify the schedule depending on the timing and nature of toxicity observed and its causality. For any modified schedule, a further 6 patients will be treated, and the new dose and schedule will only be deemed tolerable if no more than 1 out of 6 patients experience a DLT.
The Phase II study will employ a 2-stage design. It will recruit a maximum of 33 patients with a desirable response level of 30% and an undesirable response rate of 10%. Patients enrolled to the Phase I who are treated at the RP2D and are evaluable for response will contribute to the Phase II study. Patients will receive the same dose and schedule deemed to be safe in the Phase I.
In the phase II study, the first stage will enrol 15 patients who are evaluable for response. If at least one patient responds during stage 1, a further 18 patients will be recruited (stage 2). The decision to proceed to stage 2 can be made once one response has been observed after thorough review of the cases where objective response was observed by the SRC. The trial will be terminated with the conclusion that the treatment is futile if no responses are observed in the first 15 patients. The second stage of the trial will enrol 18 patients who are evaluable for response. If >6 patients respond across the 2 stages, the study will have met its efficacy threshold. Further details of the Simon 2-stage design are specified in section 13. If <7 patients respond across the 2 stages, all samples will be analysed to identify predictive biomarkers of response. If a robust biomarker is identified, the study may be expanded in a biomarker-selected cohort following protocol amendment. Further safety analysis of safety (at least 2 further interim looks) will occur throughout the phase II trial.
Approximately 6 patients will be enrolled to the Phase I and up to a total of 33 response evaluable patients will be enrolled to the Phase II study. Patients in the Phase I study who are treated with the RP2D and are evaluable for response can contribute to the Phase II study. Based on this, up to 39 response evaluable patients will be recruited across the 2 phases. Based on a recruitment rate of 3 patients per month across the 2 sites, recruitment will be completed within 24 months.
- Being tested
- Enzalutamide 40mg, Amoxicillin 500mg, Metronidazole 400mg, Vancomycin 125mg, Ciprofloxacin 500g
- Keywords
- Microbiome, Antibiotic, Enzalutamide
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Enzalutamide 40mgDrug
Also called Xtandi
Enzalutamide is presented in 40mg yellow film-coated tablets. They are supplied in a cardboard wallet incorporated a PVC/PCTFE/aluminium blister pack which holds 28 tablets. Each carton contains 4 wallets (112 tablets in total)
Amoxicillin 500mgDrug
Red / Buff coloured size '0' capsules containing white to off white powder printed with 'AMOXY 500 ' in black ink
OR
White to off-white granular powder filled in hard gelatine capsule shells size '0'. Scarlet colour cap, buff colour body printed with 'AMOXY' on cap and '500' on body
OR
White/Maroon size '0' capsules containing white to yellowish granular powder
Metronidazole 400mgDrug
Yellow, circular (11mm), biconvex, film-coated tablets with '400' debossed on one side and plain on other side
OR
White to off white coloured, caplet shaped (17.00 x 6.00 mm) film-coated tablets, debossed "400" on one side and plain on other side
OR
Off-white coloured, round, biconvex uncoated tablets engraved "MZ 400" \& break line on one side and plain on other
Vancomycin 125mgDrug
Grey/pink 17.8 ± 0.40 mm hard capsules each containing 125mg, containing white to off white congealed liquid mixture as solid mass
OR
Dark blue and brown hard capsules, imprinted with 3125 in red ink
OR
Brown 21.4 ± 0.40 mm hard capsule, containing white to off white congealed liquid mixture as solid mass
Ciprofloxacin 500gDrug
White to off white, capsule shaped, film coated tablets, with a score line on one side and debossed with 'F22' on the other side. The tablet can be divided into equal doses. The size is 18.2 mm x 8.1 mm
OR
White, caplet shaped film-coated tablets debossed with '500' on one side and plain on the other side
OR
White to off-white, capsule shape, biconvex with bevelled edge, film coated tablet with inscription 'CI' on one side and plain on the other side
OR
White, oval shaped film-coated tablets debossed 'C500' on one side and breakline on other side
| Study group | Role | What they receive |
|---|---|---|
| mCRPC patients dose with a combination of enzalutamide and antibiotics | Experimental | Phase I:
The evaluation of the safety and tolerability of the combinations of amoxicillin plus metronidazole, and ciprofloxacin plus vancomycin with enzalutamide.
Phase II:
Determination of the anti-tumour activity of the combinations of amoxicillin plus metronidazole, and ciprofloxacin plus vancomycin with enzalutamide. Receives: Drug: Enzalutamide 40mg; Drug: Amoxicillin 500mg; Drug: Metronidazole 400mg; Drug: Vancomycin 125mg; Drug: Ciprofloxacin 500g |
What is being measured
The primary outcome is the main question the study is designed to answer.
Confirm the safety and tolerability of the combination of amoxicillin plus metronidazole (2 weeks) followed by ciprofloxacin plus vancomycin (2 weeks) along with enzalutamide in Phase I in mCRPC patients.
Determine a dose at which no more than one patient out of up to 6 patients experiences a highly probable or probably drug-related DLT, during the 28-day DLT period.
Measured: 28 days
Describe the safety profile of the antibiotic combinations along with enzalutamide in Phase I.
Causality and grading severity of each adverse event related to the investigational agents according to the NCI CTCAE v5.0.
Measured: 28 days
Determine the response rate of the antibiotic combinations in patients with mCRPC in Phase II.
Anti-tumour activity will be defined by response rate on the basis of the following outcomes. If any of the following occur, patients will be considered to have responded:
- PSA decline ≥ 50% criteria confirmed 4 weeks or later, and/or
- Confirmed soft tissue objective response by RECIST (v1.1) in patients with measurable disease.
Measured: 28 days
Secondary outcomes (12)
To document possible anti-tumour activity in patients in Phase I.
Antitumour activity will be defined by response rate on the same basis as that used for the primary objective of the Phase II component.
Measured: 28 days
To evaluate progression-free survival (PFS) in mCRPC patients receiving the antibiotic combinations in Phase I.
PFS will be measured from the date of antibiotic commencement to the date of progression as determined by radiological criteria (RECIST v 1.1, PCWG3 bone scan criteria) or unequivocal clinical progression necessitating drug discontinuation (e.g. worsening pain, spinal cord compression, need for other anticancer therapy).
Measured: 12 months
To evaluate PFS in mCRPC patients receiving the antibiotic combinations along with enzalutamide in Phase II.
PFS will be measured from the date of antibiotic commencement to:
- The date of progression as determined by radiological criteria (RECIST v1.1, PCWG3 bone scan criteria) and/or
- Unequivocal clinical progression necessitating drug discontinuation (e.g. worsening pain, spinal cord compression, need for other anticancer therapy).
Measured: 12 months
To determine the time to PSA progression from the date of antibiotic commencement
This is an estimate of the biochemical anti-tumour activity of the combination of amoxicillin plus metronidazole (2-weeks) followed by ciprofloxacin plus vancomycin (2-weeks) along with enzalutamide.
Measured: 28 days
To determine the duration of PSA decline as an estimate of the biochemical anti-tumour activity of the combination of amoxicillin plus metronidazole (2-weeks) followed by ciprofloxacin plus vancomycin (2-weeks) along with enzalutamide.
The duration of PSA decline by ≥ 50% is an estimate of the biochemical anti-tumour activity of the combination of amoxicillin plus metronidazole (2-weeks) followed by ciprofloxacin plus vancomycin (2-weeks) along with enzalutamide.
Measured: 28 days
To determine the maximum percentage and absolute PSA decline from baseline
This is an estimate of the biochemical anti-tumour activity of the combination of amoxicillin plus metronidazole (2-weeks) followed by ciprofloxacin plus vancomycin (2-weeks) along with enzalutamide.
Measured: 28 days
To determine the radiologic PFS (rPFS) of the combination of antibiotics and enzalutamide in Phase II.
Radiologic PFS (rPFS) measured from the date of of antibiotic commencement to:
- Progression of soft tissue/visceral disease by RECIST (v1.1) and/or,
- Progression of bone disease by PCWG3 bone scan criteria
- And/or death from any cause
Measured: 12 months
To determine the time to radiologic progression to the combination of antibiotics and enzalutamide in Phase II.
Time to radiologic progression defined from the date of antibiotic commencement to radiologic progression by RECIST v1.1 and/or PCWG3 criteria.
Measured: 28 days
To estimate the OS in mCRPC patients receiving the antibiotic combinations along with enzalutamide in Phase II.
OS will be measured from the date of antibiotic commencement to date of death (whatever the cause).
Measured: 28 days
To further characterise the safety and tolerability profile of the antibiotic combinations with enzalutamide in Phase II.
Causality and grading severity of each adverse event related the investigational agents according to the National Cancer Institute (NCI) Common Terminology Criteria for Adverse Events (CTCAE) Version 5.0 (v5.0)
Measured: 28 days
To identify biomarkers of response to the antibiotic combinations and of anti-tumour activity in Phase II.
Biomarkers of response include tumour genomics and immunologic characteristics in tumour biopsies from responders and non-responders
Measured: 28 days
To evaluate the peripheral circulation neutrophil-to-lymphocyte ratio (NLR) as a determinant of response to to treatment in Phase II.
NLR at baseline and on-treatment for:
- Baseline NLR as a determinant of response
- Percentage change in NLR between baseline and NLR nadir between responders versus non-responders
Measured: 28 days
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted13 Nov 2023
- Study start2 Nov 2023
- Primary completion30 Jun 2026 (estimated)
- Study completion30 Jun 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Metastatic Castration-Resistant Prostate Cancer (mCRPC)Studies of the same condition, open and under way.
- More trials run by Institute of Cancer Research, United KingdomThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 1/2
- Primary purpose
- Treatment
- Allocation
- Not applicable
- Intervention model
- Single group
- Model description
- Patients with histologically or cytologically confirmed mCRPC who have previously progressed on at least one line of taxane chemotherapy (or not fit or not willing to receive a taxane) and a next generation antiandrogen (e.g. enzalutamide, apalutamide, darolutamide, abiraterone acetate)
- Masking
- None (open label)
- Enrolment
- 39 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Institute of Cancer Research, United Kingdom
- Sponsor type
- University, hospital or other
- Collaborators
- Prostate Cancer Foundation
- Responsible party
- Sponsor
- Investigators
- Johann De Bono, MD, Principal investigator, National Health Service, United Kingdom
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06126731
- Sponsor's protocol ID
- CCR5461
- Status last verified
- Nov 2025
- First submitted
- 25 Oct 2023
- Last updated
- 24 Nov 2025
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
Study at a glance
From the registry record, last updated by the sponsor on 24 Nov 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- PROMIZE: A Phase I/II Trial to Assess the Safety, Tolerability and Preliminary Anti-tumour Activity of Oral Combination Antibiotic Therapy to Modulate the Microbiome in Combination With Enzalutamide With Metastatic Castration Resistant Prostate Cancer (mCRPC).
- ClinicalTrials.gov ID
- NCT06126731
- Acronym / sponsor ID
- CCR5461
- Keywords
- Microbiome, Antibiotic, Enzalutamide
- Phase
- Phase 1/2
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 39 participants (estimated)
- Lead sponsor
- Institute of Cancer Research, United KingdomUniversity, hospital or other
- Collaborators
- Prostate Cancer Foundation
- Study start
- 2 Nov 2023 (actual)
- Primary completion
- 30 Jun 2026 (estimated)
- Study completion
- 30 Jun 2027 (estimated)
- First posted
- 13 Nov 2023 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
PROMIZE is an open-label, multi-centre, single-arm, Phase I/II clinical trial, evaluating the safety, tolerability and anti-tumuor efficacy of an antibiotic combination and enzalutamide in patients with metastatic castration-resistant prostate cancer (mCRPC).
Detailed description
Patients with histologically confirmed metastatic castration-resistant adenocarcinoma of the prostate refractory to conventional therapy (or for which no conventional therapy exists or is declined by the patient), that have progressed after at least 1 line of taxane based chemotherapy (or not fit or not willing to receive a taxane) and a NAAT are eligible for the study. The Phase I will evaluate the safety and tolerability of the combination of amoxicillin plus metronidazole (2 weeks) followed by ciprofloxacin plus vancomycin (2 weeks) administered for 2 cycles (i.e., 8 weeks) in addition to enzalutamide (160 mg daily). Enzalutamide will continue beyond the completion of the antibiotic combination until disease progression, intolerance, or withdrawal from the study. The DLT period is 4 weeks and commences at the time of combination treatment with antibiotics plus enzalutamide. Each cycle of treatment will be 4 weeks in length.
The design permits the safety monitoring of DLT regularly throughout the 2 phases. During the Phase I study, if 2 or more patients experience a DLT out of up to 6 patients, the schedule will be deemed intolerable, and a decision will be made by the SRC to modify the schedule depending on the timing and nature of toxicity observed and its causality. For any modified schedule, a further 6 patients will be treated, and the new dose and schedule will only be deemed tolerable if no more than 1 out of 6 patients experience a DLT.
The Phase II study will employ a 2-stage design. It will recruit a maximum of 33 patients with a desirable response level of 30% and an undesirable response rate of 10%. Patients enrolled to the Phase I who are treated at the RP2D and are evaluable for response will contribute to the Phase II study. Patients will receive the same dose and schedule deemed to be safe in the Phase I.
In the phase II study, the first stage will enrol 15 patients who are evaluable for response. If at least one patient responds during stage 1, a further 18 patients will be recruited (stage 2). The decision to proceed to stage 2 can be made once one response has been observed after thorough review of the cases where objective response was observed by the SRC. The trial will be terminated with the conclusion that the treatment is futile if no responses are observed in the first 15 patients. The second stage of the trial will enrol 18 patients who are evaluable for response. If >6 patients respond across the 2 stages, the study will have met its efficacy threshold. Further details of the Simon 2-stage design are specified in section 13. If <7 patients respond across the 2 stages, all samples will be analysed to identify predictive biomarkers of response. If a robust biomarker is identified, the study may be expanded in a biomarker-selected cohort following protocol amendment. Further safety analysis of safety (at least 2 further interim looks) will occur throughout the phase II trial.
Approximately 6 patients will be enrolled to the Phase I and up to a total of 33 response evaluable patients will be enrolled to the Phase II study. Patients in the Phase I study who are treated with the RP2D and are evaluable for response can contribute to the Phase II study. Based on this, up to 39 response evaluable patients will be recruited across the 2 phases. Based on a recruitment rate of 3 patients per month across the 2 sites, recruitment will be completed within 24 months.
Study design
- Primary purpose
- Treatment
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 1
- Model description
- Patients with histologically or cytologically confirmed mCRPC who have previously progressed on at least one line of taxane chemotherapy (or not fit or not willing to receive a taxane) and a next generation antiandrogen (e.g. enzalutamide, apalutamide, darolutamide, abiraterone acetate)
| Arm | Type | Receives |
|---|---|---|
| mCRPC patients dose with a combination of enzalutamide and antibiotics | Experimental | Drug: Enzalutamide 40mg, Drug: Amoxicillin 500mg, Drug: Metronidazole 400mg, Drug: Vancomycin 125mg, Drug: Ciprofloxacin 500gPhase I: The evaluation of the safety and tolerability of the combinations of amoxicillin plus metronidazole, and ciprofloxacin plus vancomycin with enzalutamide. Phase II: Determination of the anti-tumour activity of the combinations of amoxicillin plus metronidazole, and ciprofloxacin plus vancomycin with enzalutamide. |
Who may qualify
- Ages
- 18 years and older
- Sex
- Male only
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (26 listed)
- Histologically or cytologically proven metastatic castration-resistant prostate cancer or adenocarcinoma refractory to conventional treatment, or for which no conventional therapy exists or is declined by the patient.
- Documented prostate cancer progression as assessed by the investigator with RECIST (v1.1) and PCWG3 criteria with at least one of the following criteria:
- Phase I: Patients that have progressed after at least 12 weeks of treatment with a NAAT within the previous 6 months Phase II: Patients that have progressed after at least 12 weeks of treatment with a NAAT within the previous 6 months (for combination treatment) or more than 6 months prior to trial entry (for enzalutamide alone resistance run-in).
- Previously progressed on at least one line of taxane chemotherapy (or not fit or not willing to receive a taxane).
- Ongoing androgen deprivation maintaining serum testosterone of less than 50 ng/dL (less than 2.0 nM) is mandatory.
Key exclusion criteria (31 listed)
- Surgery, radiotherapy, chemotherapy, or other anti-cancer therapy within 4-weeks prior to trial entry into the study (6 weeks for bicalutamide). The use of bisphosphonates or RANK ligand inhibitors in patients with known osteopenia or osteoporosis or bone metastases is permitted. Prior antiandrogenic treatment exclusions as follows:
- Ongoing toxic manifestations of previous treatments. Exceptions to this are alopecia or certain Grade 1 toxicities, which in the opinion of the Investigator and the DDU should not exclude the patient.
- Previous treatment with any systemic antibiotic within 12 weeks of study entry.
- Known hypersensitivity reaction or intolerance to any penicillin, amoxicillin, metronidazole, vancomycin, ciprofloxacin or enzalutamide.
- History of tendon disorder secondary to quinolones
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Enzalutamide 40mgAlso: XtandiEnzalutamide is presented in 40mg yellow film-coated tablets. They are supplied in a cardboard wallet incorporated a PVC/PCTFE/aluminium blister pack which holds 28 tablets. Each carton contains 4 wallets (112 tablets in total) | Drug | mCRPC patients dose with a combination of enzalutamide and antibiotics |
| Amoxicillin 500mgRed / Buff coloured size '0' capsules containing white to off white powder printed with 'AMOXY 500 ' in black ink OR White to off-white granular powder filled in hard gelatine capsule shells size '0'. Scarlet colour cap, buff colour body printed with 'AMOXY' on cap and '500' on body OR White/Maroon size '0' capsules containing white to yellowish granular powder | Drug | mCRPC patients dose with a combination of enzalutamide and antibiotics |
| Metronidazole 400mgYellow, circular (11mm), biconvex, film-coated tablets with '400' debossed on one side and plain on other side OR White to off white coloured, caplet shaped (17.00 x 6.00 mm) film-coated tablets, debossed "400" on one side and plain on other side OR Off-white coloured, round, biconvex uncoated tablets engraved "MZ 400" \& break line on one side and plain on other | Drug | mCRPC patients dose with a combination of enzalutamide and antibiotics |
| Vancomycin 125mgGrey/pink 17.8 ± 0.40 mm hard capsules each containing 125mg, containing white to off white congealed liquid mixture as solid mass OR Dark blue and brown hard capsules, imprinted with 3125 in red ink OR Brown 21.4 ± 0.40 mm hard capsule, containing white to off white congealed liquid mixture as solid mass | Drug | mCRPC patients dose with a combination of enzalutamide and antibiotics |
| Ciprofloxacin 500gWhite to off white, capsule shaped, film coated tablets, with a score line on one side and debossed with 'F22' on the other side. The tablet can be divided into equal doses. The size is 18.2 mm x 8.1 mm OR White, caplet shaped film-coated tablets debossed with '500' on one side and plain on the other side OR White to off-white, capsule shape, biconvex with bevelled edge, film coated tablet with inscription 'CI' on one side and plain on the other side OR White, oval shaped film-coated tablets debossed 'C500' on one side and breakline on other side | Drug | mCRPC patients dose with a combination of enzalutamide and antibiotics |
Primary outcome
Confirm the safety and tolerability of the combination of amoxicillin plus metronidazole (2 weeks) followed by ciprofloxacin plus vancomycin (2 weeks) along with enzalutamide in Phase I in mCRPC patients.
Time frame: 28 days
Determine a dose at which no more than one patient out of up to 6 patients experiences a highly probable or probably drug-related DLT, during the 28-day DLT period.
Describe the safety profile of the antibiotic combinations along with enzalutamide in Phase I.
Time frame: 28 days
Causality and grading severity of each adverse event related to the investigational agents according to the NCI CTCAE v5.0.
Determine the response rate of the antibiotic combinations in patients with mCRPC in Phase II.
Time frame: 28 days
Anti-tumour activity will be defined by response rate on the basis of the following outcomes. If any of the following occur, patients will be considered to have responded: * PSA decline ≥ 50% criteria confirmed 4 weeks or later, and/or * Confirmed soft tissue objective response by RECIST (v1.1) in patients with measurable disease.
12 secondary outcomes
To document possible anti-tumour activity in patients in Phase I.
Time frame: 28 days
To evaluate progression-free survival (PFS) in mCRPC patients receiving the antibiotic combinations in Phase I.
Time frame: 12 months
To evaluate PFS in mCRPC patients receiving the antibiotic combinations along with enzalutamide in Phase II.
Time frame: 12 months
To determine the time to PSA progression from the date of antibiotic commencement
Time frame: 28 days
To determine the duration of PSA decline as an estimate of the biochemical anti-tumour activity of the combination of amoxicillin plus metronidazole (2-weeks) followed by ciprofloxacin plus vancomycin (2-weeks) along with enzalutamide.
Time frame: 28 days
To determine the maximum percentage and absolute PSA decline from baseline
Time frame: 28 days
To determine the radiologic PFS (rPFS) of the combination of antibiotics and enzalutamide in Phase II.
Time frame: 12 months
To determine the time to radiologic progression to the combination of antibiotics and enzalutamide in Phase II.
Time frame: 28 days
To estimate the OS in mCRPC patients receiving the antibiotic combinations along with enzalutamide in Phase II.
Time frame: 28 days
To further characterise the safety and tolerability profile of the antibiotic combinations with enzalutamide in Phase II.
Time frame: 28 days
To identify biomarkers of response to the antibiotic combinations and of anti-tumour activity in Phase II.
Time frame: 28 days
To evaluate the peripheral circulation neutrophil-to-lymphocyte ratio (NLR) as a determinant of response to to treatment in Phase II.
Time frame: 28 days
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 24 Nov 2025.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Johann De Bono, MD principal investigator
National Health Service, United Kingdom
2 sites in 2 countries: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 1/2 study testing Enzalutamide 40mg, Amoxicillin 500mg and Metronidazole 400mg in people with Metastatic Castration-Resistant Prostate Cancer (mCRPC), run by Institute of Cancer Research, United Kingdom at 2 sites in 2 countries.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 26 inclusion and 31 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 24 Nov 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 2 sites in Switzerland, United Kingdom. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this combined phase mean?
Phase 1 studies test a treatment in a small group of people for the first time or in a new way, mainly to check safety and find the right dose.
Phase 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact PROMIZE Team (02087224497, PROMIZE@icr.ac.uk), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Confirm the safety and tolerability of the combination of amoxicillin plus metronidazole (2 weeks) followed by ciprofloxacin plus vancomycin (2 weeks) along with enzalutamide in Phase I in mCRPC patients. (time frame: 28 days). The study lists 3 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 24 Nov 2025.