Breast CancerPhase 2NCT05020574
Microbiome and Association With Implant Infections
A Phase 2 study testing Cephalexin in people with Breast Cancer and Breast Cancer Female, run by University of California, San Francisco at 1 site in United States.
Trial summary
The most common tissue expander-related infections are from Staphylococcus and Pseudomonas species. In addition, from breast tissue microbiome studies, Staphylococcus and Pseudomonas show variable abundance across samples. Read more about this study
- Who is it for?
- Ages 18 years and older, women only
- Conditions the study is for
- Breast Cancer, Breast Cancer Female, Genetic Predisposition to Disease
- What is being tested?
- Cephalexin
- Type of treatment
- Pill or oral medicine
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 200 participants
- Where
- 1 siteUnited States
- Study dates
- 28 Sep 2021to 31 Dec 2026
- Phase
- Phase 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
- Women only
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Patients must have histologically confirmed breast malignancy OR genetic predisposition to breast cancer.
- Age >= 18 years
- Scheduled to undergo mastectomy with the immediate placement of tissue expanders or implant placement
- Ability to understand a written informed consent document, and the willingness to sign it
- At least 4 weeks post-completion of chemotherapy or radiation therapy.
Who cannot join
- Any significant medical condition or laboratory abnormalities, which places the subject at unacceptable risk if he/she were to participate in the study
- Pregnant or breastfeeding
- Patients who have taken antibiotics within 90 days of the consent date
- Patients who have taken probiotics within 90 days of the consent date
- Patients who have a documented or reported allergic reaction to the outlined antibiotics to be used in this study
- Male patients
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
United States1 site, 1 recruiting
- Recruiting
University of California, San Francisco
San Francisco, California, 94143
Laura Barnes, MD, 415-502-1259, Laura.Barnes@ucsf.edu
877-827-3222, cancertrials@ucsf.edu
About this study
Official title: Microbiome and Association With Implant Infections: Investigating the Impact of Antibiotics on the Gut and Breast Microbiomes Post-mastectomy With Implant-based Breast Reconstruction
The most common tissue expander-related infections are from Staphylococcus and Pseudomonas species. In addition, from breast tissue microbiome studies, Staphylococcus and Pseudomonas show variable abundance across samples. The investigator hypothesizes that participants undergoing mastectomy with high initial abundance of Staphylococcus and/or Pseudomonas are more likely to develop subsequent tissue expander-related infections from these respective organisms.
Read the detailed description
PRIMARY OBJECTIVE:
- To determine the feasibility of breast microbiome sampling using the study techniques
SECONDARY OBJECTIVES:
- To define the differences in the gut and breast microbiomes between participants undergoing mastectomy with implant-based reconstruction who develop post-operative implant infection and those who do not.
II. To determine the effects of post-operative antibiotics on the gut and breast microbiomes after mastectomy with implant-based reconstruction.
OUTLINE: Participants are randomized to 1 of 2 cohorts.
COHORT A: Participants receive postoperative antibiotics to take for at least 7 days post-operatively.
COHORT B: Participants receive no antibiotics post-operatively in the absence of clinical evidence of infection.
Participants are followed up for 90 days.
- Being tested
- Cephalexin
- Keywords
- Post-Surgical Antibiotics, Breast Implant Infections, Breast Microbiome, Breast Reconstruction, Mastectomy
- Medical subject headings
- Breast Neoplasms, Genetic Predisposition to Disease
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
CephalexinDrug
Also called Keflex
Given orally (PO)
| Study group | Role | What they receive |
|---|---|---|
| Cohort A: Standard antibiotics | Experimental | Receive standard pre-incision antibiotics and 24-hour perioperative antibiotics - Prescribed standard postoperative antibiotics to take for at least 7 days post-operatively Receives: Drug: Cephalexin |
| Cohort B: No antibiotics | No intervention | Receive standard pre-incision antibiotics and 24-hour perioperative antibiotics - No antibiotics post-operatively, unless patient develops clinical evidence of infection |
What is being measured
The primary outcome is the main question the study is designed to answer.
Proportion of tissue samples obtained successfully over time
The feasibility of success in obtaining samples from breast tissue will be measured as a binary outcome (successful or not successful) over time (intra-operatively, week 1, week 2, week 3, and week 4). The investigators will assess and document success in obtaining a tissue sample immediately at the time of sampling of each participant.
Measured: 90 days
Proportion of aspirate samples obtained successfully overall
The feasibility of success in obtaining samples from the tissue expander aspiration ports will be measured as a binary outcome (successful or not successful) over time (intra-operatively, week 1, week 2, week 3, and week 4). The investigators will assess and document success in obtaining a aspirate sample immediately at the time of sampling of each participant.
Measured: 90 days
Proportion of tissue samples successfully producing microbiome data
Feasibility based off of the success rates in producing microbiome data from tissue samples in each patient will be measured as a binary outcome (successful or not successful) and will be reported.
Measured: 90 days
Proportion of aspirate samples successfully producing microbiome data
Feasibility based off of the success rates in producing microbiome data from tissue samples in each patient will be measured as a binary outcome (successful or not successful) and will be reported.
Measured: 90 days
Proportion of any samples successfully producing microbiome data
Feasibility based off of the success rates in producing microbiome data from tissue or aspirate samples in each patient will be measured as a binary outcome (successful or not successful) and will be reported.
Measured: 90 days
Correlation of the change in breast microbiome over time with total duration of antibiotics (Cohort A only)
The investigators will analyze the microbiomes between groups, between microbiome environments (gut v. breast, inter-individual). The correlate of change in breast microbiome over time will be compared to the total duration of antibiotics for Cohort A only. The measure of association ranges from +1 to -1, with a value of zero equal to no association.
Measured: 90 days
Secondary outcomes (3)
Proportion of participants with post-operative infection
Safety will be assessed by clinically assessing for signs of post-operative infection in each patient at each clinic visit. A post-operative infection is defined by clinical assessment of findings of surgical site erythema, tenderness, edema, and/or purulent drainage +/- fever. Proportion of participants with clinically diagnosed infection will be reported for each group and final diagnosis for analyses will be binary; a participant will either have a post-operative infection in the 90 day post-operative period or not have a post-operative infection in the 90 day post-operative period.
Measured: 90 days
Shannon Diversity Index Score for species of microbiome
Alpha diversity will be evaluated for species richness by number of operational taxonomic units and for evenness using the Shannon Index. The Shannon diversity index (H) is an index that is commonly used to characterize species diversity in a community and accounts for both abundance and evenness of the species present. The proportion of species (i) relative to the total number of species (pi) is calculated, and then multiplied by the natural logarithm of this proportion (lnpi). The resulting product is summed across species, and multiplied by -1. Shannon's equitability (EH) can be calculated by dividing H by Hmax (here Hmax = lnS). Equitability assumes a value between 0 and 1 with 1 being complete evenness and the overall index score is represented by a percentage of the species.
Measured: 90 days
Number of overall identified microbes
The investigators will evaluate microbial composition by grouping identified microbes into operational taxonomic units at the species, genera and phyla levels and will compare the relative abundances of these microbes between groups at the species, gene
Measured: 90 days
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted25 Aug 2021
- Study start28 Sep 2021
- Primary completion31 Dec 2026 (estimated)
- Study completion31 Dec 2026 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Breast CancerStudies of the same condition, open and under way.
- More trials run by University of California, San FranciscoThe 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 2
- Primary purpose
- Supportive care
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Enrolment
- 200 participants (estimated)
Sponsor and investigators
- Lead sponsor
- University of California, San Francisco
- Sponsor type
- University, hospital or other
- Collaborators
- The Plastic Surgery Foundation
- Responsible party
- Sponsor
- Investigators
- Merisa Piper, MD, Principal investigator, University of California, San Francisco
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05020574
- Sponsor's protocol ID
- 217510
- Other IDs
- NCI-2021-08985
- Status last verified
- Mar 2026
- First submitted
- 20 Aug 2021
- Last updated
- 18 Mar 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 18 Mar 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Microbiome and Association With Implant Infections: Investigating the Impact of Antibiotics on the Gut and Breast Microbiomes Post-mastectomy With Implant-based Breast Reconstruction
- ClinicalTrials.gov ID
- NCT05020574
- Acronym / sponsor ID
- 217510
- Keywords
- Post-Surgical Antibiotics, Breast Implant Infections, Breast Microbiome, Breast Reconstruction, Mastectomy
- Phase
- Phase 2
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 200 participants (estimated)
- Lead sponsor
- University of California, San FranciscoUniversity, hospital or other
- Collaborators
- The Plastic Surgery Foundation
- Study start
- 28 Sep 2021 (actual)
- Primary completion
- 31 Dec 2026 (estimated)
- Study completion
- 31 Dec 2026 (estimated)
- First posted
- 25 Aug 2021 (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.
The most common tissue expander-related infections are from Staphylococcus and Pseudomonas species. In addition, from breast tissue microbiome studies, Staphylococcus and Pseudomonas show variable abundance across samples. The investigator hypothesizes that participants undergoing mastectomy with high initial abundance of Staphylococcus and/or Pseudomonas are more likely to develop subsequent tissue expander-related infections from these respective organisms.
Detailed description
PRIMARY OBJECTIVE:
- To determine the feasibility of breast microbiome sampling using the study techniques
SECONDARY OBJECTIVES:
- To define the differences in the gut and breast microbiomes between participants undergoing mastectomy with implant-based reconstruction who develop post-operative implant infection and those who do not.
II. To determine the effects of post-operative antibiotics on the gut and breast microbiomes after mastectomy with implant-based reconstruction.
OUTLINE: Participants are randomized to 1 of 2 cohorts.
COHORT A: Participants receive postoperative antibiotics to take for at least 7 days post-operatively.
COHORT B: Participants receive no antibiotics post-operatively in the absence of clinical evidence of infection.
Participants are followed up for 90 days.
Study design
- Primary purpose
- Supportive care
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Cohort A: Standard antibiotics | Experimental | Drug: CephalexinReceive standard pre-incision antibiotics and 24-hour perioperative antibiotics - Prescribed standard postoperative antibiotics to take for at least 7 days post-operatively |
| Cohort B: No antibiotics | No intervention | –Receive standard pre-incision antibiotics and 24-hour perioperative antibiotics - No antibiotics post-operatively, unless patient develops clinical evidence of infection |
Who may qualify
- Ages
- 18 years and older
- Sex
- Female only
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (5 listed)
- Patients must have histologically confirmed breast malignancy OR genetic predisposition to breast cancer.
- Age >= 18 years
- Scheduled to undergo mastectomy with the immediate placement of tissue expanders or implant placement
- Ability to understand a written informed consent document, and the willingness to sign it
- At least 4 weeks post-completion of chemotherapy or radiation therapy.
Key exclusion criteria (6 listed)
- Any significant medical condition or laboratory abnormalities, which places the subject at unacceptable risk if he/she were to participate in the study
- Pregnant or breastfeeding
- Patients who have taken antibiotics within 90 days of the consent date
- Patients who have taken probiotics within 90 days of the consent date
- Patients who have a documented or reported allergic reaction to the outlined antibiotics to be used in this study
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 |
|---|---|---|
| CephalexinAlso: KeflexGiven orally (PO) | Drug | Cohort A: Standard antibiotics |
Primary outcome
Proportion of tissue samples obtained successfully over time
Time frame: 90 days
The feasibility of success in obtaining samples from breast tissue will be measured as a binary outcome (successful or not successful) over time (intra-operatively, week 1, week 2, week 3, and week 4). The investigators will assess and document success in obtaining a tissue sample immediately at the time of sampling of each participant.
Proportion of aspirate samples obtained successfully overall
Time frame: 90 days
The feasibility of success in obtaining samples from the tissue expander aspiration ports will be measured as a binary outcome (successful or not successful) over time (intra-operatively, week 1, week 2, week 3, and week 4). The investigators will assess and document success in obtaining a aspirate sample immediately at the time of sampling of each participant.
Proportion of tissue samples successfully producing microbiome data
Time frame: 90 days
Feasibility based off of the success rates in producing microbiome data from tissue samples in each patient will be measured as a binary outcome (successful or not successful) and will be reported.
Proportion of aspirate samples successfully producing microbiome data
Time frame: 90 days
Feasibility based off of the success rates in producing microbiome data from tissue samples in each patient will be measured as a binary outcome (successful or not successful) and will be reported.
Proportion of any samples successfully producing microbiome data
Time frame: 90 days
Feasibility based off of the success rates in producing microbiome data from tissue or aspirate samples in each patient will be measured as a binary outcome (successful or not successful) and will be reported.
Correlation of the change in breast microbiome over time with total duration of antibiotics (Cohort A only)
Time frame: 90 days
The investigators will analyze the microbiomes between groups, between microbiome environments (gut v. breast, inter-individual). The correlate of change in breast microbiome over time will be compared to the total duration of antibiotics for Cohort A only. The measure of association ranges from +1 to -1, with a value of zero equal to no association.
3 secondary outcomes
Proportion of participants with post-operative infection
Time frame: 90 days
Shannon Diversity Index Score for species of microbiome
Time frame: 90 days
Number of overall identified microbes
Time frame: 90 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 18 Mar 2026.
- Individual participant dataSharing planned: No
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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.
Merisa Piper, MD principal investigator
University of California, San Francisco
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 2 study testing Cephalexin in people with Breast Cancer and Breast Cancer Female, run by University of California, San Francisco at 1 site in United States.
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 5 inclusion and 6 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 18 Mar 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. 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 phase mean?
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 Laura Barnes, MD ((415) 502-1259, Laura.Barnes@ucsf.edu), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Proportion of tissue samples obtained successfully over time (time frame: 90 days). The study lists 6 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 18 Mar 2026.