MedPath

(Z)-Endoxifen for the Treatment of Premenopausal Women With ER+/HER2- Breast Cancer

Phase 2
Recruiting
Conditions
Breast Neoplasms
Invasive Breast Cancer
Estrogen-receptor-positive Breast Cancer
HER2-negative Breast Cancer
Interventions
Registration Number
NCT05607004
Lead Sponsor
Atossa Therapeutics, Inc.
Brief Summary

This open-label research study is studying (Z)-endoxifen as a possible treatment for pre-menopausal women with ER+/HER2- breast cancer. (Z)-endoxifen belongs to a group of drugs called selective estrogen receptor modulators or "SERM", which help block estrogen from attaching to cancer cells. This study has two parts: a pharmacokinetic part and a treatment part.

The PK part (how the body processes the drug) will enroll about 18 participants. All participants will take (Z)-endoxifen capsules daily. Twelve participants will be randomly assigned (50/50 chance) to take (Z)-endoxifen alone or (Z)-endoxifen with a monthly injection of goserelin a drug that temporarily stops the ovaries from making estrogen. This part will help determine the best dose of (Z)-endoxifen by measuring the drug levels in the blood and how long the body takes to remove it.

The treatment part has two parts:

* Part 2a will enroll 162 participants whose tumors have a high level of cell proliferation as indicated by the presence of a biomarker called Ki-67 (greater than 10%). Participants will be randomly assigned to one of two groups (50/50 chance):

1. a group receiving (Z)-endoxifen daily with a monthly injection of goserelin

2. a group receiving the current standard treatment of exemestane (an aromatase inhibitor that lowers estrogen) with a monthly injection of goserelin.

* The Part 2b will enroll about 30 participants whose tumors have low Ki-67 levels (10% or less). These participants will take daily (Z)-endoxifen alone without goserelin.

A key goal of the study is to see if (Z)-endoxifen can slow down or stop tumor growth as measured by a reduction in Ki-67 levels. Tumor tissue samples will be taken by breast biopsy after about 4 weeks of treatment to check levels of this biomarker. If the tumor shows signs of response, participants can continue treatment for up to 24 weeks or until they have surgery.

Study participation is up to 6 months (24 weeks of treatment) followed by surgery and a one-month follow up visit.

Detailed Description

Not available

Recruitment & Eligibility

Status
RECRUITING
Sex
Female
Target Recruitment
214
Inclusion Criteria
  1. Female sex assigned at birth

  2. Age 18 years or older

  3. Not lactating, pregnant, or planning to become pregnant in the next year and agrees to take adequate steps to prevent becoming pregnant beginning at informed consent, during treatment and for 9 months after last dose and agree to not breast feed during treatment and for 3 months after last dose.

  4. Must agree to use at least one non-hormonal highly effective method of contraception for the entire duration of study participation beginning at informed consent. Highly effective methods of birth control are defined as those, alone or in combination, that resulted in a low failure rate of <1% per year when used consistently and correctly such as intrauterine devices (IUDs, non-hormonal such as copper IUD), bilateral tubal occlusion, sexual abstinence or vasectomized partner

  5. Premenopausal defined as any female who:

    1. is menstruating or
    2. is not menstruating (last menstrual period > 3 months prior to registration) but has a plasma estradiol in the premenopausal range as assessed locally
  6. Pathologic confirmation of strongly estrogen receptor positive (ER+) (defined as estrogen receptor [ER] ≥ 67% or Allred Score 6-8) by local institution protocol

  7. Treatment Cohort Part 2a, Randomized Treatment Cohort: Local pathology laboratory finding of Ki-67 > 10% in invasive breast cancer specimen obtained at or after diagnosis but prior to any anti-tumor treatment

  8. Treatment Cohort Part 2b, Single Arm Treatment Cohort: Local pathology laboratory finding of Ki- ≤ 10% in invasive breast cancer specimen obtained at or after diagnosis but prior to any anti-tumor treatment

  9. Eastern Cooperative Oncology Group ECOG Performance Status (ECOG PS) of 0 to 2

  10. Nottingham (Elston-Ellis) Grade 1 or 2

  11. HER2- breast cancer (histologically confirmed) using American Society of Clinical Oncology (ASCO)/College of American Pathologists (CAP) guidelines

  12. Clinical T2 or T3 invasive breast cancer (per American Joint Committee on Cancer [AJCC] 8th edition clinical staging)

  13. Clinical N0 or N1 invasive breast cancer (per American Joint Committee on Cancer [AJCC] 8th edition clinical staging)

  14. MRI ≤ 35 days of registration

  15. Mammogram performed ≤ 90 days of registration (Treatment Cohort Parts 2a and 2b only)

  16. Must have given written informed consent before any study-related activities are carried out and must be able to understand the full nature and purpose of the trial, including possible risks and adverse effects

  17. Willing to provide blood and breast tissue samples for research purposes at specified timepoints for the duration of their participation in the trial.

Exclusion Criteria
  1. Bilateral invasive breast cancer; Inflammatory breast cancer defined as clinically significant erythema of the breast and/or documented dermal lymphatic invasion or bilateral invasive breast cancer (patients with pre-malignant disease or DCIS/LCIS in contralateral breast are eligible)

  2. Prior diagnosis or treatment for breast cancer, including carcinoma in situ, or history of any other active malignancy within the past 2 years prior to study entry with the exception of:

    1. Adequately treated in situ carcinoma of the cervix uteri
    2. Adequately treated basal cell carcinoma or localized squamous cell carcinoma of the skin
    3. Any other malignancy with a life expectancy of less than 2 years
  3. Any uncontrolled intercurrent illness including, but not limited to:

    1. Ongoing or active infection requiring systemic treatment with strong inhibitors/inducers of CYP450 enzymes (including bacterial infection, fungal infection, or detectable viral infection).
    2. Symptomatic congestive heart failure,
    3. Unstable angina pectoris,
    4. Uncontrolled symptomatic cardiac arrhythmias
    5. Uncontrolled hypertension
    6. Uncontrolled diabetes (Hemoglobin A1c [HbA1c] >7%)
    7. Marked baseline prolongation of QT/QTc interval (e.g., repeated demonstration of a QTc interval > 470 milliseconds [msec]) using Fridericia's QT correction formula seen ≤ 28 days of registration
  4. Any of the following co-morbid conditions:

    1. Known cataracts or retinopathy
    2. History of deep vein thrombosis (DVT)/pulmonary embolism (PE)
    3. Known activated protein C (APC) resistance, an inherited coagulation disorder
    4. End stage kidney disease requiring dialysis
  5. Evidence of the following laboratory abnormalities ≤ 28 days prior to registration:

    1. Total bilirubin ≥ 1.5 x upper limit of normal (ULN)
    2. Aspartate aminotransferase (AST) or alanine amino transferase (ALT) ≥ 2.5 x ULN
    3. Platelet count (PLT) ≤ 75,000/mm3
    4. Hemoglobin (Hb) ≤ 10 g/dL
  6. Hormonal therapies including birth control and hormone replacement therapy, or prior use of androgen-based therapy during the study or within 1 week of registration. If subject has a prior medical history of Depo-Provera®, it is recommended that the last dose of 3-month contraceptive agents are > 2.5 months from registration.

  7. Allergy to endoxifen, goserelin, or exemestane or any of their components

  8. Participation in another investigational clinical trial ≤ 6 months of registration

  9. Known metastatic disease

  10. History of polycystic ovarian syndrome (Treatment Cohort Part 2b ONLY)

Study & Design

Study Type
INTERVENTIONAL
Study Design
PARALLEL
Arm && Interventions
GroupInterventionDescription
Treatment Cohort Part 2a Arm 1 Initial RegimengoserelinParticipants with Ki-67 value of \>10% at Pre-registration visit: (Z)-endoxifen 40mg capsules orally once daily for 4 weeks + goserelin 3.6 mg by subcutaneous implant approximately every 28 days. (Z)-endoxifen 40mg dose based on results of PK Cohort. If Ki-67 ≤ 10% at Week 4, continue on this treatment for up to 6 cycles/Week 24. Each cycle is 28 days. And then go on to surgery within 3 weeks of Cycle 6 day 26. If Ki-67 \> 10% at Week 4, participant will be offered to switch treatment to Exemestane 25 mg orally once daily + goserelin 3.6 mg by subcutaneous implant for 4 weeks and then collect Ki-67 value either by a breast biopsy or go on to surgery.
Treatment Cohort Part 2a Arm 2 Initial RegimenexemestaneParticipants with Ki-67 value of \>10% at Pre-registration visit: Exemestane 25 mg orally once daily for 4 weeks + goserelin 3.6 mg by subcutaneous implant approximately every 28 days. If Ki-67 ≤ 10% at Week 4, continue on this treatment for up to 6 cycles/Week 24. Each cycle is 28 days. And then go on to surgery within 3 weeks of Cycle 6 day 26. If Ki-67 \> 10% at Week 4, participant will complete early termination assessments.
Treatment Cohort Part 2a Arm 2 Initial RegimengoserelinParticipants with Ki-67 value of \>10% at Pre-registration visit: Exemestane 25 mg orally once daily for 4 weeks + goserelin 3.6 mg by subcutaneous implant approximately every 28 days. If Ki-67 ≤ 10% at Week 4, continue on this treatment for up to 6 cycles/Week 24. Each cycle is 28 days. And then go on to surgery within 3 weeks of Cycle 6 day 26. If Ki-67 \> 10% at Week 4, participant will complete early termination assessments.
Treatment Cohort Part 2a Arm 1 Modified RegimenexemestaneExemestane 25 mg orally once daily for 4 weeks + goserelin 3.6 mg by subcutaneous implant approximately every 28 days. After 4 weeks of modified regimen, Ki-67 value will be collected by breast biopsy or surgery. Early termination assessments will follow.
Treatment Cohort Part 2a Arm 1 Modified RegimengoserelinExemestane 25 mg orally once daily for 4 weeks + goserelin 3.6 mg by subcutaneous implant approximately every 28 days. After 4 weeks of modified regimen, Ki-67 value will be collected by breast biopsy or surgery. Early termination assessments will follow.
PK Cohort 80 mg + OFSgoserelin(Z)-endoxifen 80 mg capsules orally once daily for 4 weeks + goserelin 3.6 mg by subcutaneous implant approximately every 28 days. The PK Cohort participants may extend treatment based on Ki-67% at Week 4. If Ki-67 ≤ 10% at Week 4, participant will be offered option to continue on this treatment for up to 6 cycles/Week 24. Each cycle is 28 days. If Ki-67 \> 10% at Week 4, participant will be withdrawn and go on to surgery.
PK Cohort(Z)-endoxifen(Z)-endoxifen capsules orally once daily for 4 weeks. Initial (Z)-endoxifen dose evaluated will be 40 mg with an option to evaluate 20 mg or 80 mg. The PK Cohort participants may extend treatment based on Ki-67% at Week 4. If Ki-67 ≤ 10% at Week 4, participant will be offered option to continue on this treatment for up to 6 cycles/Week 24. Each cycle is 28 days. If Ki-67 \> 10% at Week 4, participant will be withdrawn and go on to surgery.
Treatment Cohort Part 2a Arm 1 Initial Regimen(Z)-endoxifenParticipants with Ki-67 value of \>10% at Pre-registration visit: (Z)-endoxifen 40mg capsules orally once daily for 4 weeks + goserelin 3.6 mg by subcutaneous implant approximately every 28 days. (Z)-endoxifen 40mg dose based on results of PK Cohort. If Ki-67 ≤ 10% at Week 4, continue on this treatment for up to 6 cycles/Week 24. Each cycle is 28 days. And then go on to surgery within 3 weeks of Cycle 6 day 26. If Ki-67 \> 10% at Week 4, participant will be offered to switch treatment to Exemestane 25 mg orally once daily + goserelin 3.6 mg by subcutaneous implant for 4 weeks and then collect Ki-67 value either by a breast biopsy or go on to surgery.
PK Cohort 80 mg(Z)-endoxifen(Z)-endoxifen 80 mg capsules orally once daily for 4 weeks. The PK Cohort participants may extend treatment based on Ki-67% at Week 4. If Ki-67 ≤ 10% at Week 4, participant will be offered option to continue on this treatment for up to 6 cycles/Week 24. Each cycle is 28 days. If Ki-67 \> 10% at Week 4, participant will be withdrawn and go on to surgery.
PK Cohort 80 mg + OFS(Z)-endoxifen(Z)-endoxifen 80 mg capsules orally once daily for 4 weeks + goserelin 3.6 mg by subcutaneous implant approximately every 28 days. The PK Cohort participants may extend treatment based on Ki-67% at Week 4. If Ki-67 ≤ 10% at Week 4, participant will be offered option to continue on this treatment for up to 6 cycles/Week 24. Each cycle is 28 days. If Ki-67 \> 10% at Week 4, participant will be withdrawn and go on to surgery.
Treatment Cohort Part 2b Single Arm(Z)-endoxifenParticipants with Ki-67 value of ≤ 10% at Pre-registration visit: (Z)-endoxifen 40 mg capsules orally once daily for 4 weeks. If Ki-67 ≤ 10% at Week 4, participant will be offered option to continue on this treatment for up to 6 cycles/Week 24. Each cycle is 28 days. And then go on to surgery. If Ki-67 \> 10% at Week 4, participant will complete early termination visit and go on to surgery.
Primary Outcome Measures
NameTimeMethod
PK Cohort - (Z)-endoxifen steady-state plasma concentrationsAfter 4 weeks of treatment

(Z)-endoxifen steady-state plasma concentrations (Css) of evaluable subjects who completed at least one cycle of treatment (28 +/- 3 days)

Treatment Cohort Part 2a - Endocrine sensitive disease rate based on Ki-67 percent after 4 weeks of treatmentAfter 4 weeks of treatment

Endocrine sensitive disease rate will be estimated as the percentage of subjects whose 4-week tumor biopsy finds Ki-67 less than or equal to 10 percent among evaluable subjects who began protocol treatment

Treatment Cohort Part 2b - Endocrine sensitive disease rate based on Ki-67 percentage after 24 weeks of treatment.After 24 weeks of treatment

Endocrine sensitive disease rate will be estimated as the percentage of subjects whose surgical tumor biopsy finds Ki-67 less than or equal to 10 percent among evaluable subjects who began protocol treatment.

Secondary Outcome Measures
NameTimeMethod
PK Cohort - Area under the plasma (Z)-endoxifen concentration-time curve from time zero to last measurable concentrationDays 1 and 28

Area under the plasma (Z)-endoxifen concentration-time curve from time zero to last measurable concentration (AUC0-24) on Days 1 and 28 of evaluable subjects who completed at least one cycle of treatment (28 +/- 3 days)

PK Cohort - Area under the plasma (E)-endoxifen concentration-time curve from time zero to last measurable concentrationDays 1 and 28

Area under the plasma (E)-endoxifen concentration-time curve from time zero to last measurable concentration (AUC0-24) on Days 1 and 28 of evaluable subjects who completed at least one cycle of treatment (28 +/- 3 days)

PK Cohort - Accumulation and accumulation half-lifeDays 1 and 28

Accumulation and accumulation half-life (Day 28 AUC0-24/Day 1 AUC0-24) of evaluable subjects who completed at least one cycle of treatment (28 +/- 3 days)

PK Cohort - (Z)-endoxifen steady-state clearanceup to 28 days

(Z)-endoxifen CLss (steady-state clearance) of evaluable subjects who completed at least one cycle of treatment (28 +/- 3 days)

PK Cohort - (E)-endoxifen steady-state clearanceup to 28 days

(E)-endoxifen CLss (steady-state clearance) of evaluable subjects who completed at least one cycle of treatment (28 +/- 3 days)

PK Cohort - Maximum plasma (Z)-endoxifen concentrationup to 28 days

Maximum plasma (Z)-endoxifen concentration (Cmax) of evaluable subjects who completed at least one cycle of treatment (28 +/- 3 days)

PK Cohort - Maximum plasma (E)-endoxifen concentrationup to 28 days

Maximum plasma (E)-endoxifen concentration (Cmax) of evaluable subjects who completed at least one cycle of treatment (28 +/- 3 days)

PK Cohort - Time to plasma (Z)-endoxifen maximum concentrationup to 28 days

Time to plasma (Z)-endoxifen maximum concentration (Tmax) of evaluable subjects who completed at least one cycle of treatment (28 +/- 3 days)

PK Cohort - Time to plasma (E)-endoxifen maximum concentrationup to 28 days

Time to plasma (E)-endoxifen maximum concentration (Tmax) of evaluable subjects who completed at least one cycle of treatment (28 +/- 3 days)

PK Cohort - plasma (Z)-endoxifen concentrationDay 1 up to 12 weeks and up to end of treatment or up to 24 weeks.

Trough concentrations of (Z)-endoxifen for subjects in the Treatment Extension

PK Cohort - plasma (E)-endoxifen concentrationDay 1 up to 12 weeks and up to end of treatment or up to 24 weeks.

Trough concentrations of (Z)-endoxifen for subjects in the Treatment Extension

PK Cohort and Treatment Cohort Part 2a- Endocrine sensitive disease rate based on Ki-67 percent after 4 weeks of treatmentAfter 4 weeks of treatment

Endocrine sensitive disease rate will be estimated as the percentage of subjects whose 4-week tumor biopsy finds Ki-67 less than or equal to 10 percent among evaluable subjects who began protocol treatment

Both Cohorts - Incidence of Adverse Events assessed by CTCAE version 5.0Informed consent up to follow up visit or up to 30 weeks

Incidence and severity of adverse events per CTCAE by treatment

Both Cohorts - Incidence of Serious Adverse Events assessed by CTCAE version 5.0Informed consent up to follow up visit or up to 30 weeks

Incidence of serious adverse events by treatment

Both Cohorts - Incidence of Adverse Events Leading to DiscontinuationInformed consent up to end of treatment or up to 24 weeks

Incidence of adverse events leading to discontinuation by treatment

Both Cohorts - Incidence of Dose ReductionsDay 1 up to time of surgery or up to 27 weeks

Proportion of patients who required a dose reduction by treatment arm

Both Cohorts - Change in estradiol and estroneDay 1, up to 4 weeks, up to 12 weeks and up to end of treatment or up to 24 weeks.

Median percent change in the E1/E2 ratio

Both Cohorts - Percentage of subjects whose serum thymidine kinase 1 (TK1) falls below the detection limit after 4 weeks of treatment and 24 weeks.Day 1, up to 4 weeks, up to 12 weeks and up to end of treatment or up to 24 weeks.

Percentage of subjects whose serum TK1 falls below the detection limit (\< 20 DiviTum units per liter Du/L) after one cycle of treatment among those with detectable serum TK1 levels prior to start of protocol treatment

Both Cohorts - Changes from baselineInformed consent up to follow up visit or up to 30 weeks

Changes from baseline in vital signs, physical examination findings, clinical laboratory parameters, ECG findings

Both Cohorts - Assess additional PK parameters of (Z)-endoxifen and (E)-endoxifenDay 1, up to 4 weeks, up to 12 weeks and up to 24 weeks

Tissue and plasma (Z)-endoxifen and (E)-endoxifen concentrations at 4 weeks and 24 weeks

Treatment Cohort - Radiographic Response Rate in the breastBaseline Assessment, up to 4 weeks, up to 12 weeks, and up to 24 weeks

Radiographic response rate in the breast at 4, 12, and 24 weeks as assessed by RECIST 1.1 criteria

Treatment Cohort - Pathologic Complete Response per American Joint Committee on Cancer staging system at time of surgeryAt time of surgery or up to 27 weeks

Pathologic Complete Response (pCR) at surgery defined as the absence of residual invasive breast cancer on hematoxylin and eosin evaluation of the resected breast specimen and of all sampled lymph nodes (sentinel ± axillary) removed following completion of neoadjuvant systemic therapy

Treatment Cohort - Pre-Operative Endocrine Prognostic Index at time of surgeryAt time of surgery or up to 27 weeks

Rate of Pre-Operative Endocrine Prognostic Index (PEPI) 0 at time of surgery using residual tumor specimen

Treatment Cohort - Residual Cancer Burden at time of surgeryAt time of surgery or up to 27 weeks

Rate of residual cancer burden class of 0-I at time of surgery

Treatment Cohort - Conversion RateFrom baseline to time of surgery or up to 27 weeks

Evaluate the conversion rate from breast conservation surgery ineligible to breast conservation surgery eligible. Evaluation is based on surgeon's impression of the type of surgery participant is eligible for (candidate for lumpectomy, candidate for modified radical mastectomy, inoperable) at baseline compared to surgeon's impression after completion of neoadjuvant treatment

Treatment Cohort - Actual Conversion RateAt time of surgery or up to 27 weeks

Evaluate the actual rate of breast conservation surgery. Evaluation will be based on the extent of the surgical procedure at the time of surgery (lumpectomy, partial or segmental mastectomy, simple/total mastectomy, skin and/or nipple sparing mastectomy, radical mastectomy or other)

Treatment Cohort - Change in blood pressurebaseline, up to 4 weeks, and up to 24 weeks

Change from pre-neoadjuvant treatment in blood pressure

Treatment Cohort Part 2b - safety and tolerability of (Z)-endoxifen monotherapyDay 1 up to week 24

Incidence and severity of ovarian cysts as documented by pelvic ultrasound

Treatment Cohort - Change in fasting glucosebaseline, up to 4 weeks, and up to 24 weeks

Change from pre-neoadjuvant treatment in fasting glucose

Treatment Cohorts - Change in menopause quality of life (MENQOL)baseline, up to 4 weeks, and up to 24 weeks

Evaluate changes in menopause symptoms after neoadjuvant treatment

Treatment Cohorts - Change in mammographic density area (cm2)baseline up to Week 24

Change in mammographic breast density area (cm2) assessed by iCAD®

Treatment Cohorts - Nodal response rateAt time of surgery or up to 27 weeks

Rate of nodal pCR in subjects with biopsy proven nodal disease

Trial Locations

Locations (12)

Tranquility Research

🇺🇸

Webster, Texas, United States

Bon Secours Cancer Institute

🇺🇸

Midlothian, Virginia, United States

Mayo Clinic Arizona

🇺🇸

Phoenix, Arizona, United States

University of Arizona

🇺🇸

Tucson, Arizona, United States

Mayo Clinic Florida

🇺🇸

Jacksonville, Florida, United States

Northwestern University

🇺🇸

Chicago, Illinois, United States

St. Elizabeth Healthcare

🇺🇸

Edgewood, Kentucky, United States

Henry Ford Cancer Institute

🇺🇸

Detroit, Michigan, United States

Mayo Clinic Rochester

🇺🇸

Rochester, Minnesota, United States

Washington University School of Medicine

🇺🇸

Saint Louis, Missouri, United States

Avera Cancer Institute

🇺🇸

Sioux Falls, South Dakota, United States

Vanderbilt Ingram Cancer Center

🇺🇸

Nashville, Tennessee, United States

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