A Phase 1 interventional study of BBI-355 and Erlotinib in Triple Negative Breast Cancer (TNBC), High Grade Serous Ovarian Carcinoma and High Grade Endometrial Carcinoma, sponsored by Boundless Bio, Inc.. Terminated at 16 sites in United States. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-08-19.
Sponsored by Boundless Bio, Inc. · Phase 1, Interventional, and Treatment
BBI-355 is an oral, potent, selective checkpoint kinase 1 (or CHK1) small molecule inhibitor in development as an ecDNA (extrachromosomal DNA) directed therapy (ecDTx). BBI-825 is an oral, potent, selective ribonucleotide reductase (or RNR) small molecule inhibitor. This is a first-in-human, open-label, 2-part, Phase 1/2 study to determine the safety profile and identify the maximum tolerated dose and recommended Phase 2 dose of BBI-355 administered as a single agent or in combination with BBI-825 or other select therapies.
BBI-355 and BBI-825 are administered orally in various dosing schedules to subjects with locally advanced or metastatic non-resectable solid tumors harboring oncogene amplifications, whose disease has progressed despite all standard therapies or for whom no further standard or clinically acceptable therapy exists.
1,219 studies on the registry are indexed under Triple Negative Breast Neoplasms; 446 are open to participants now.
This study's enrollment of 85 is above the median of 60 across 1,053 interventional studies indexed under Triple Negative Breast Neoplasms.
Browse Triple Negative Breast Neoplasms studies →Boundless Bio, Inc. is the lead sponsor of 3 studies on the registry; none are open to participants now.
Counted across the registry records on this site, refreshed daily.
Key Inclusion Criteria:
Key Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Cancer that has spread from where it began to other parts of the body. “Metastatic” cancer is cancer that has spread this way.
The amount of disease can be tracked with a defined measurement, so the study can see whether it shrinks or grows. It might be a tumour measured on a scan or, in some blood cancers such as myeloma, a marker measured in blood or urine.
The criteria or the study team say which measurement counts — having no tumour visible on a scan does not by itself rule you out.
The standard rules for measuring tumours on CT or MRI scans, to tell whether a cancer is shrinking, stable or growing during treatment.
“Measurable disease per RECIST 1.1” usually means at least one tumour 10 mm or more at its longest on a CT scan, or a lymph node 15 mm or more across its short axis.
A scale of how much an illness limits everyday activity. For people being assessed to join a study, scores run from 0 (fully active) to 4; lower is more active.
Studies most often ask for 0–1 or 0–2. Your doctor gives the score; the WHO scale uses the same steps. The full scale also has 5, which records death.
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
Cancer that has spread to the leptomeninges, the thin layers covering the brain and spinal cord, and the fluid between them. It is not the same as brain metastases.
Criteria often treat it separately, and many studies leave it out even where treated brain metastases are allowed.
Cancer deposits in the brain from a cancer that started elsewhere in the body (CNS metastases include the spinal cord).
Studies differ: some leave out any brain metastases, some accept ones treated and stable for some weeks. Check what this study allows.
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
Hepatitis C is a virus that infects the liver. An HCV antibody test can stay positive after an infection has cleared (and is occasionally positive without one); an HCV RNA test shows whether the virus is there now.
After treatment, hepatitis C counts as cured when HCV RNA is still undetectable 12 weeks or more after the treatment ended. Studies often accept people cured this way.
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
A weakened immune system. It can come from an illness, such as HIV or some blood cancers, or from medicines that turn the immune system down, for example after an organ transplant or for an autoimmune disease; steroids at higher doses count.
Read whether the line is about a condition or about medicines, and which medicines and doses it means.
On an ECG, the QT interval is the time the heart’s lower chambers take to activate electrically and recover in each beat. QTc is that time adjusted for heart rate (QTcF by Fridericia’s formula, QTcB by Bazett’s). Some medicines lengthen it, and a long QTc can raise the risk of a dangerous heart rhythm.
The study may name a correction formula and a limit in milliseconds, often around 450–480.
Metastases
Cancer that has spread from where it began to other parts of the body. “Metastatic” cancer is cancer that has spread this way.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Measurable disease
The amount of disease can be tracked with a defined measurement, so the study can see whether it shrinks or grows. It might be a tumour measured on a scan or, in some blood cancers such as myeloma, a marker measured in blood or urine.
The criteria or the study team say which measurement counts — having no tumour visible on a scan does not by itself rule you out.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
RECIST
The standard rules for measuring tumours on CT or MRI scans, to tell whether a cancer is shrinking, stable or growing during treatment.
“Measurable disease per RECIST 1.1” usually means at least one tumour 10 mm or more at its longest on a CT scan, or a lymph node 15 mm or more across its short axis.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ECOG performance status
A scale of how much an illness limits everyday activity. For people being assessed to join a study, scores run from 0 (fully active) to 4; lower is more active.
Studies most often ask for 0–1 or 0–2. Your doctor gives the score; the WHO scale uses the same steps. The full scale also has 5, which records death.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Cancer (malignancy)
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Leptomeningeal disease
Cancer that has spread to the leptomeninges, the thin layers covering the brain and spinal cord, and the fluid between them. It is not the same as brain metastases.
Criteria often treat it separately, and many studies leave it out even where treated brain metastases are allowed.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Brain metastases
Cancer deposits in the brain from a cancer that started elsewhere in the body (CNS metastases include the spinal cord).
Studies differ: some leave out any brain metastases, some accept ones treated and stable for some weeks. Check what this study allows.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hepatitis B tests
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hepatitis C tests
Hepatitis C is a virus that infects the liver. An HCV antibody test can stay positive after an infection has cleared (and is occasionally positive without one); an HCV RNA test shows whether the virus is there now.
After treatment, hepatitis C counts as cured when HCV RNA is still undetectable 12 weeks or more after the treatment ended. Studies often accept people cured this way.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
HIV
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Clinically significant
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Corticosteroids (steroids)
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Immunosuppression
A weakened immune system. It can come from an illness, such as HIV or some blood cancers, or from medicines that turn the immune system down, for example after an organ transplant or for an autoimmune disease; steroids at higher doses count.
Read whether the line is about a condition or about medicines, and which medicines and doses it means.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
QT and QTc
On an ECG, the QT interval is the time the heart’s lower chambers take to activate electrically and recover in each beat. QTc is that time adjusted for heart rate (QTcF by Fridericia’s formula, QTcB by Bazett’s). Some medicines lengthen it, and a long QTc can raise the risk of a dangerous heart rhythm.
The study may name a correction formula and a limit in milliseconds, often around 450–480.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Single agent BBI-355, administered orally in 28-day cycles
Drug: BBI-355
Single agent BBI-355, administered orally in 28-day cycles
Drug: BBI-355
Combination therapy of BBI-355 and EGFR inhibitor erlotinib, administered orally in 28-day cycles.
Drug: BBI-355 · Drug: Erlotinib
Combination therapy of BBI-355 and FGFR1-4 inhibitor futibatinib, administered orally in 28-day cycles.
Drug: BBI-355 · Drug: Futibatinib
Combination therapy of BBI-355 and RNR Inhibitor BBI-825, administered orally in 28-day cycles.
Drug: BBI-355 · Drug: BBI-825
Oral CHK1 inhibitor
EGFR Inhibitor
FGFR1-4 Inhibitor
Oral RNR Inhibitor
Frequency and severity of treatment emergent adverse events (TEAEs) of BBI-355 as a single agent and in combination with each of the following agents: erlotinib, futibatinib, or BBI-825
TEAEs will be assessed and severity assigned by using the National Cancer Institute Common Terminology Criteria for Adverse Events (NCI CTCAE), version 5.0.
Time frame: Start of Cycle 1 until 30 days following last dose (each cycle is 28 days)
Maximum Tolerated Dose (MTD) and/or Recommended Phase 2 Dose (RP2D) of BBI-355 as a single agent and in combination with erlotinib, futibatinib, or BBI-825
The MTD and/or RP2D of BBI-355 as a single agent and in combination with erlotinib, futibatinib, or BBI-825 will be determined.
Time frame: Start of Cycle 1 until 30 days following last dose (each cycle is 28 days)
Maximum observed plasma concentration (Cmax) of BBI-355, erlotinib, futibatinib, and BBI-825
Maximum observed plasma concentration (Cmax) of BBI-355, erlotinib, futibatinib, and BBI-825 will be determined.
Time frame: Start of Cycle 1 until Day 1 of last treatment cycle (each cycle is 28 days)
Trough observed plasma concentration (Ctrough) of BBI-355, erlotinib, futibatinib, and BBI-825
Trough observed plasma concentration (Ctrough) of BBI-355, erlotinib, futibatinib and BBI-825 will be determined.
Time frame: Start of Cycle 1 until Day 1 of last treatment cycle (each cycle is 28 days)
Time to Cmax (Tmax) of BBI-355, erlotinib, futibatinib, and BBI-825
Time to Cmax (Tmax) of BBI-355, erlotinib, futibatinib, and BBI-825 will be determined.
Time frame: Start of Cycle 1 until Day 1 of last treatment cycle (each cycle is 28 days)
Area under the concentration time curve (AUC) of BBI-355, erlotinib, futibatinib, and BBI-825
Area under the concentration time curve (AUC) of BBI-355, erlotinib, futibatinib and BBI-825 will be determined.
Time frame: Start of Cycle 1 until Day 1 of last treatment cycle (each cycle is 28 days)
Anti-tumor activity of BBI-355 as a single agent and in combination with erlotinib, futibatinib, or BBI-825
Tumor response will be determined by RECISTv1.1.
Time frame: 1-2 years: Start of Cycle 1 until documented disease progression or death (each cycle is 28 days)
Plan to share: No
This study is terminated, as verified in Jun 2026. You cannot join it, but the record below documents what was studied.
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Triple Negative Breast Neoplasms →
Boundless Bio, Inc.