OncoMatch/Clinical Trials/NCT04872166
A Study of BTX-A51 in People With Advanced Solid Tumor and Breast Cancer
Is NCT04872166 recruiting? Yes, currently enrolling (Jun 2026). This Phase 1 trial studies BTX-A51 for advanced solid tumor.
Treatment: BTX-A51 — This is a multicenter, open label, nonrandomized, sequential dose escalation/dose ranging, multiple dose study designed to evaluate the safety, toxicity, and PK as well as preliminary efficacy of BTX-A51 alone and in combination with fulvestrant in subjects with advanced solid tumors. The study will be done in three phases, described below. Phase 1a (Dose Escalation Phase): The Phase 1a portion is designed to determine the dose limiting toxicities (DLTs), maximum tolerated dose (MTD), and recommended Phase 2 dose (RP2D) of orally administered BTX-A51. BTX-A51 will be administered once daily on a weekly schedule of 5 days on/2 days off. Dose escalation will proceed according to a modified 3+3 design. Each cycle will consist of 28 days (4 weeks), and the DLT observation period will be the first cycle (i.e., 28 days after initiation of dosing). A DLT may be observed in no more than 0 out of 3 or 1 out of 6 subjects who have completed the DLT observation period before the next cohort initiates accrual. Barring DLT, sequential dose escalation of BTX-A51 is planned with up to a total of 6 dose levels; on the basis of these an MTD will be identified. The MTD is defined as the highest dose level with a subject incidence of DLTs of 0 or 1 out of 6 during the first 28 days of study drug dosing. A minimum of 6 subjects needs to be treated at a dose level before this dose level can be deemed as the MTD. Phase 1b (Monotherapy Dose Ranging Phase): Dose expansion may begin when the RP2D has been determined. Up to 40 additional subjects at each of the 2 dose levels will be enrolled to evaluate safety and preliminary efficacy of BTX-A51 in subjects with estrogen receptor positive (ER+), human epidermal growth factor receptor 2 negative (HER2-), GATA3 mutant (mt) and wild-type (wt) metastatic breast cancer (mBC). Dosing in this phase of the study consists of the first cycle of therapy (i.e., 28 days). Phase 1c (Combination Safety Phase): The Phase 1c portion will evaluate the safety and tolerability of orally administered BTX-A51 at two dose levels combined with fulvestrant. The first combo cohort may be initiated after DEC review of the 6 subject lead-in phase of the high dose monotherapy cohort in Phase 1b. Dose escalation will proceed according to a 3+3 design. Each cycle will consist of 28 days (4 weeks), and the DLT observation period will be the first cycle (i.e., 28 days after initiation of dosing).
Check if I qualifyExtracted eligibility criteria
Treatments studied
Other
Cancer type
Tumor Agnostic
Breast Carcinoma
Biomarker criteria
Required: ESR1 positive (ER+)
Histologically confirmed diagnosis of ER+, HER2- mBC
Required: HER2 (ERBB2) wild-type (HER2-)
Histologically confirmed diagnosis of ER+, HER2- mBC
Disease stage
Required: Stage IV
Metastatic disease required
incurable or metastatic solid tumor that is refractory to or intolerant of all standard therapy or for which no standard therapy is available; Histologically confirmed diagnosis of ER+, HER2- mBC not amenable to resection or radiation therapy with curative intent
Prior therapy
Must have received: all standard therapy
refractory to or intolerant of all standard therapy or for which no standard therapy is available
Cannot have received: local or systemic antineoplastic therapy
Treatment with any local or systemic antineoplastic therapy (including chemotherapy, hormonal therapy, or radiation) within 3 weeks prior to first dose of BTX-A51
Lab requirements
Blood counts
adequate organ function
Kidney function
adequate organ function
Liver function
adequate organ function
Adequate organ function
Structured fields extracted by AI. May contain errors — verify against the official protocol.
US trial sites
- Florida Cancer Specialists · Lake Mary, Florida
- Florida Cancer Specialists · Sarasota, Florida
- The Linder Research Center at The Christ Hospital · Cincinnati, Ohio
- SCRI Oncology Partners · Nashville, Tennessee
- Tennessee Oncology, PLLC · Nashville, Tennessee
Showing up to 5 US sites.
See all sites on ClinicalTrials.gov →Frequently asked questions
Is NCT04872166 currently recruiting?
Yes, this trial is currently recruiting patients.
Are there prior therapy exclusions?
Yes. Prior local or systemic antineoplastic therapy disqualifies patients from enrollment.
Does this trial require ESR1?
Yes, ESR1 positive is a required biomarker for enrollment.
Does this trial require ERBB2?
Yes, ERBB2 wild-type is a required biomarker for enrollment.
What disease stage is eligible?
Stage IV is required (metastatic disease required).
Could you qualify for this trial?
Enter your biomarker results to see how this trial's eligibility criteria match your specific cancer profile.
Check if I qualifyRelated pages