BTX-9341 + Fulvestrant for Breast Cancer

Recruiting at4 trial locations

Age: 18+

Sex: Any

Travel: May Be Covered

Time Reimbursement: Varies

Trial Phase: Phase 1

Recruiting

Sponsor: Biotheryx, Inc.

Must be taking: Fulvestrant

Must not be taking: Anticoagulants

Disqualifiers: RB1 mutation, CNS metastasis, others

No Placebo Group

Trial Summary

What is the purpose of this trial?

The purpose of this study is to test BTX-9341 alone or in combination with fulvestrant (a currently marketed medication for breast cancer) in participants with advanced and/or metastatic hormone receptor positive (HR+)/human epidermal growth factor receptor 2 negative (HER2-) breast cancer. The study includes a dose escalation part (Part A) where small groups of participants will receive increasing doses of BTX-9341 or BTX-9341 + fulvestrant followed by a dose expansion part (Part B) where participants will receive the dose of BTX-9341 selected in Part A + fulvestrant.

Do I need to stop my current medications for this trial?

The trial protocol does not specify if you need to stop your current medications. However, it mentions that participants must have been on prior endocrine and CDK4/6 inhibitor therapies for at least 6 months before progression, suggesting that some medications may need to be continued. Please consult with the trial investigators for specific guidance.

What data supports the idea that BTX-9341 + Fulvestrant for Breast Cancer is an effective drug?

The available research shows that Fulvestrant, also known as Faslodex, is effective in treating advanced breast cancer in postmenopausal women, especially when used early in the treatment process. In one study, 39% of patients experienced clinical benefits, such as tumor shrinkage or stable disease, when treated with Fulvestrant. Another study reported a 29.9% clinical benefit rate. Fulvestrant is also well tolerated, with few patients experiencing significant side effects. Compared to Tamoxifen, another breast cancer drug, Fulvestrant is promising because it works differently and can be effective when other treatments stop working. ^{1 2 3 4 5}

What safety data is available for BTX-9341 + Fulvestrant in breast cancer treatment?

Fulvestrant, also known as Faslodex, is well tolerated in the treatment of advanced breast cancer. Common side effects are mild gastrointestinal symptoms. In various studies, only a small percentage of patients discontinued treatment due to adverse events. Fulvestrant has been used in multiple lines of therapy and is generally considered safe, with most adverse events being mild (grade I/II). ^{2 3 5 6 7}

Is the drug BTX-9341, Fulvestrant a promising treatment for breast cancer?

Yes, Fulvestrant (also known as Faslodex) is a promising drug for treating advanced breast cancer, especially in postmenopausal women. It works by blocking and breaking down estrogen receptors, which can help slow down or stop the growth of cancer cells. Studies have shown that it can be effective even when other treatments have stopped working, and it is generally well-tolerated by patients. ^{2 3 4 6 8}

Research Team

Jeremy Barton, MD

Principal Investigator

Chief Medical Officer

Eligibility Criteria

This trial is for individuals with advanced or metastatic HR+/HER2- breast cancer. Participants should have a type of breast cancer that has spread and responds to hormones but not the HER2 protein. They will test BTX-9341 alone or with fulvestrant, which is already used for this cancer.

Inclusion Criteria

Able and willing to sign informed consent

My breast cancer has spread and is HR+/HER2-.

Meets all study requirements in the opinion of the Investigator

Exclusion Criteria

I have symptoms caused by cancer in my internal organs.

My cancer has spread to my brain or spinal cord.

My cancer has a mutation in the RB1 gene.

Trial Timeline

Screening

Participants are screened for eligibility to participate in the trial

2-4 weeks

Dose Escalation (Part A)

Participants receive increasing doses of BTX-9341 alone or in combination with fulvestrant to determine the maximum tolerated dose (MTD) or minimum effective dose (MED)

Approximately 1 year

28-day cycles with regular monitoring

Dose Expansion (Part B)

Participants receive the selected dose of BTX-9341 in combination with fulvestrant to evaluate objective response rate

Approximately 18 months

28-day cycles with regular monitoring

Follow-up

Participants are monitored for safety and effectiveness after treatment

Up to 28 days after last dose of BTX-9341

Treatment Details

Interventions

• BTX-9341 (Other)
• Fulvestrant (Hormone Therapy)

Trial Overview The study tests BTX-9341's safety and effectiveness, both on its own and combined with fulvestrant. It starts by giving small groups increasing doses of BTX-9341 (Part A), then moves to more people getting the best dose found plus fulvestrant (Part B).

Participant Groups

Group I: BTX-9341 + fulvestrant (Part B) Experimental Treatment 2 Interventions

BTX-9341 capsule(s) administered orally QD in 28-day cycles and fulvestrant intermuscular injections on Day 15 and then once every 28 days

Group II: BTX-9341 + fulvestrant (Part A) Experimental Treatment 2 Interventions

BTX-9341 capsule(s) administered orally QD in 28-day cycles and fulvestrant intermuscular injections on Day 15 and then once every 28 days

Group III: BTX-9341 (Part A) Experimental Treatment 1 Intervention

BTX-9341 capsule(s) administered orally once daily (QD) in 28-day cycles

Who Is Running the Clinical Trial?

Biotheryx, Inc.

Lead Sponsor

Trials

2

Recruited

90+

Findings from Research

Fulvestrant, an estrogen receptor antagonist, was effective in treating advanced breast cancer in postmenopausal women, showing an overall clinical benefit in 39% of the 339 patients studied, with better outcomes when used as a first-line treatment.

The treatment was well tolerated, with only 5% of patients experiencing adverse events, and it was particularly beneficial for patients with tumors expressing both estrogen and progesterone receptors.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Fulvestrant ("Faslodex"): clinical experience from the Compassionate Use Programme. Steger, GG., Gips, M., Simon, SD., et al.[2018]

In a study of 402 postmenopausal women with advanced breast cancer receiving fulvestrant through a Compassionate Use Program, 29.9% experienced clinical benefits, including partial responses and stable disease for over 6 months.

Fulvestrant was well tolerated, with only 1.5% of patients discontinuing treatment due to adverse events, indicating its safety and potential as an effective option for patients who have not responded to previous therapies.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Fulvestrant (Faslodex) in advanced breast cancer: clinical experience from a Belgian cooperative study. Neven, P., Paridaens, R., Pelgrims, G., et al.[2018]

Faslodex (fulvestrant) is a novel selective estrogen receptor down-regulator (SERD) that effectively targets and degrades the estrogen receptor, offering a new treatment option for advanced breast cancer, especially in cases where tumors have become resistant to tamoxifen.

Unlike tamoxifen, which can lead to resistance and has risks such as endometrial carcinoma, Faslodex provides a 'pure' antiestrogen effect without agonistic activity, making it a promising alternative for both advanced and early breast cancer treatment.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Faslodex(TM) for the treatment of breast cancer. Smolnikar, K.[2019]

In a study of 54 postmenopausal women with metastatic breast cancer, fulvestrant demonstrated clinical benefit in 38.9% of patients, with a median time to progression of 6.4 months, indicating its efficacy even after multiple prior treatments.

Fulvestrant was well tolerated, with no severe toxicities (grade 3/4) reported, suggesting it is a safe option for patients with advanced breast cancer who have limited treatment options.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Fulvestrant ('Faslodex') in heavily pretreated postmenopausal patients with advanced breast cancer: single centre clinical experience from the compassionate use programme. Mlineritsch, B., Psenak, O., Mayer, P., et al.[2018]

In a study involving 587 postmenopausal women with advanced breast cancer, fulvestrant showed similar efficacy to tamoxifen in patients with hormone receptor-positive tumors, with no significant differences in time to progression (TTP) or objective response rates.

While tamoxifen had a slightly better overall efficacy in the general population, both treatments were well tolerated, indicating that fulvestrant can be a viable option for patients with ER+ and/or PgR+ tumors.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Comparison of fulvestrant versus tamoxifen for the treatment of advanced breast cancer in postmenopausal women previously untreated with endocrine therapy: a multinational, double-blind, randomized trial. Howell, A., Robertson, JF., Abram, P., et al.[2022]

Fulvestrant is a novel estrogen receptor antagonist used for the palliative treatment of advanced breast cancer in postmenopausal women, and it has no known agonist effects, making it a unique option for therapy.

The drug is well tolerated with mild gastrointestinal symptoms being the most common side effect, and it is administered as a once-a-month intramuscular injection, providing a convenient treatment option for patients.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Fulvestrant antiestrogen for treatment of breast cancer. Hancock, CM.[2018]

In a study involving 126 postmenopausal women with advanced breast cancer, fulvestrant demonstrated an objective response rate of 9.5% and a clinical benefit rate of 43.6%, indicating its efficacy as a treatment option after previous endocrine therapies.

Fulvestrant was well tolerated, with only six patients experiencing mild adverse events (grade I/II), suggesting it is a safe option for patients who have progressed on prior treatments.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Fulvestrant ('Faslodex') in pre-treated patients with advanced breast cancer: a single-centre experience. Steger, GG., Bartsch, R., Wenzel, C., et al.[2018]

Fulvestrant is an estrogen receptor downregulator being developed for the treatment of advanced breast cancer in postmenopausal women, with an NDA filed in the US for its use as a second-line therapy.

The drug shows potential not only for breast cancer but also for other estrogen-responsive tumors, such as uterine tumors, although further development for these indications has not been reported since the late 1990s.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Fulvestrant (AstraZeneca). Johnston, SR.[2018]

References

1. Netherlands pubmed.ncbi.nlm.nih.gov

Fulvestrant ("Faslodex"): clinical experience from the Compassionate Use Programme. [2018]

2. Netherlands pubmed.ncbi.nlm.nih.gov

Fulvestrant (Faslodex) in advanced breast cancer: clinical experience from a Belgian cooperative study. [2018]

3. Spain pubmed.ncbi.nlm.nih.gov

Faslodex(TM) for the treatment of breast cancer. [2019]

4. Netherlands pubmed.ncbi.nlm.nih.gov

Fulvestrant ('Faslodex') in heavily pretreated postmenopausal patients with advanced breast cancer: single centre clinical experience from the compassionate use programme. [2018]

5. United States pubmed.ncbi.nlm.nih.gov

Comparison of fulvestrant versus tamoxifen for the treatment of advanced breast cancer in postmenopausal women previously untreated with endocrine therapy: a multinational, double-blind, randomized trial. [2022]

6. United States pubmed.ncbi.nlm.nih.gov

Fulvestrant antiestrogen for treatment of breast cancer. [2018]

7. England pubmed.ncbi.nlm.nih.gov

Fulvestrant ('Faslodex') in pre-treated patients with advanced breast cancer: a single-centre experience. [2018]

8. England pubmed.ncbi.nlm.nih.gov

Fulvestrant (AstraZeneca). [2018]