Tesetaxel Plus Reduced Dose of Capecitabine vs. Capecitabine in HER2 Negative, HR Positive, LA/MBC

CONTESSA is a multinational, multicenter, randomized, Phase 3 study of tesetaxel plus a
reduced dose of capecitabine versus the approved dose of capecitabine alone in patients with
HER2 negative, HR positive locally advanced or metastatic breast cancer (LA/MBC) previously
treated with a taxane in the neoadjuvant or adjuvant setting. Approximately 600 patients will
be enrolled.

Patients randomly assigned to Arm A (tesetaxel plus a reduced dose of capecitabine) will be
administered:

- Tesetaxel (27 mg/m2) orally once every 21 days on Day 1 of each 21-day cycle; and

- Capecitabine (825 mg/m2) orally twice daily (in the morning and evening after a meal,
for a total daily dose of 1,650 mg/m2) beginning with the evening dose on Day 1 through
the morning dose on Day 15 of each 21-day cycle.

Patients randomly assigned to Arm B (approved dose of capecitabine alone) will be
administered:

- Capecitabine (1,250 mg/m2) orally twice daily (in the morning and evening after a meal,
for a total daily dose of 2,500 mg/m2), beginning with the evening dose on Day 1 through
the morning dose on Day 15 of each 21-day cycle

Dose modifications for tesetaxel and/or capecitabine are described in the study protocol.

Patients will be treated until documentation of progressive disease (PD), evidence of
unacceptable toxicity, or other decision to discontinue treatment. Capecitabine is an oral
chemotherapy agent that is considered a standard-of-care treatment in LA/MBC. The primary
endpoint is PFS as assessed by an IRC. The secondary efficacy endpoints are overall survival
(OS), objective response rate (ORR) as assessed by an IRC, and disease control rate (DCR) as
assessed by an IRC.

Inclusion Criteria:

1. Female or male patients at least 18 years of age

2. Histologically or cytologically confirmed breast cancer

3. HER2 negative disease based on local testing: American Society of Clinical
Oncology/College of American Pathologists (ASCO/CAP) guidelines should be utilized for
assessing HER2 status

4. HR (estrogen receptor [ER] and/or progesterone receptor [PgR]) positive disease based
on local testing: ASCO/CAP guidelines should be utilized for assessing HR status

5. Measurable disease per RECIST 1.1 or bone-only disease with lytic component

- Patients with bone-only metastatic cancer must have a lytic or mixed
lytic-blastic lesion that can be accurately assessed by computerized tomography
(CT) or magnetic resonance imaging (MRI). Patients with bone-only disease without
a lytic component (ie, blastic-only metastasis) are not eligible.

- Known metastases to the CNS are permitted but not required. The following
criteria apply:

- Patients must be neurologically stable and either off corticosteroids or
currently treated with a maximum daily dose of 4 mg of dexamethasone (or
equivalent), with no increase in corticosteroid dose within 7 days prior to
randomization

- Patients with a history of CNS metastases but with no current evidence of
CNS lesions following local therapy are eligible

- Patients may have CNS metastases that are stable or progressing
radiologically

- Patients with current evidence of leptomeningeal disease are not eligible

- Patients may have untreated brain metastases or previously treated brain
metastases, as long as no immediate local CNS-directed therapy is indicated

- Any prior whole brain radiation therapy must have been completed > 14 days
prior to the date of randomization

- Prior stereotactic brain radiosurgery is permitted

- CNS surgical resection must have been completed > 28 days prior to the date
of randomization; patient must have complete recovery from surgery

6. Eastern Cooperative Oncology Group (ECOG) performance status 0, 1, or 2

7. Prior therapy (at least one completed dose) with a taxane-containing regimen in the
neoadjuvant or adjuvant setting

8. Prior therapy with an anthracycline-containing regimen in the neoadjuvant, adjuvant,
or metastatic setting, where indicated by local regulation or Investigator judgment.

9. Prior endocrine therapy with or without a CDK 4/6 inhibitor unless endocrine therapy
is not indicated (ie, short relapse-free interval while on adjuvant endocrine therapy
[endocrine resistance]; rapidly progressing disease/visceral crisis; or endocrine
intolerance). Any targeted therapies approved for HER2 negative, HR positive LA/MBC,
including everolimus, are permitted as prior therapy. There is no limit to the number
of prior endocrine therapies.

10. Documented disease recurrence or disease progression of: (a) locally advanced disease
that is not considered curable by surgery and/or radiation; or (b) metastatic disease.

11. Adequate hematologic, hepatic, and renal function, as evidenced by:

- Absolute neutrophil count (ANC) ≥ 1,500/μL without colony-stimulating factor
support

- Platelet count ≥ 100,000/μL

- Hemoglobin ≥ 10 g/dL without need for hematopoietic growth factor or transfusion
support

- Total bilirubin < 1.5 × upper limit of normal (ULN); does not apply to patients
with Gilbert's syndrome

- Alanine aminotransferase (ALT) < 3 × ULN unless hepatic metastases are present,
then < 5 × ULN

- Aspartate aminotransferase (AST) < 3 × ULN unless hepatic metastases are present,
then < 5 × ULN

- Alkaline phosphatase < 2.5 × ULN unless hepatic metastases are present, then < 5
× ULN

- Calculated creatinine clearance ≥ 50 mL/min (by Cockcroft-Gault formula or local
standard)

- Serum albumin ≥ 3.0 g/dL

- Prothrombin time (PT) < 1.5 × ULN or international normalized ratio (INR) < 1.3,
and partial thromboplastin time (PTT) < 1.5 × ULN, unless the patient is on a
therapeutic anticoagulant

12. Complete recovery to baseline or Grade 1 per National Cancer Institute (NCI) CTCAE
version 5.0 from adverse effects of prior surgery, radiotherapy, endocrine therapy,
and other therapy, as applicable, with the exception of Grade 2 alopecia from prior
chemotherapy

13. Ability to swallow an oral solid-dosage form of medication

14. A negative serum pregnancy test within 7 days prior to the first dose of Study
treatment in women of childbearing potential (ie, all women except those who are post
menopause for ≥ 1 year or who have a history of hysterectomy or surgical
sterilization)

15. Women of childbearing potential must use an effective, non-hormonal form of
contraception from Screening throughout the Treatment Phase and until 70 days after
the last dose of study treatment

• Acceptable methods include: copper intrauterine devices or double barrier methods,
including male/female condoms with spermicide and use of contraceptive sponge,
cervical cap, or diaphragm

16. Male patients must use an effective, non-hormonal form of contraception from screening
throughout the treatment phase and until 130 days after last dose of study treatment

• Acceptable methods include male/female condoms with spermicide, or vasectomy with
medical confirmation of surgical success

17. Written informed consent and authorization to use and disclose health information

18. Ability to comprehend and comply with the requirements of the study

Exclusion Criteria:

1. Two or more prior chemotherapy regimens for advanced disease

2. Prior treatment with a taxane in the metastatic setting

3. Prior treatment with capecitabine at any dose

4. Current evidence of leptomeningeal disease

5. Other cancer that required therapy within the preceding 5 years other than adequately
treated: (a) non-melanoma skin cancer or in situ cancer; or (b) following approval by
the sponsor medical team, other cancer that has a very low risk of interfering with
the safety or efficacy endpoints of the study

6. Known human immunodeficiency virus infection, unless well controlled. Patients who are
on an adequate antiviral regimen with no evidence of active infection are considered
well controlled.

7. Active hepatitis B or active hepatitis C infection

8. Other severe acute or chronic medical or psychiatric condition or laboratory
abnormality that may increase the risk associated with study participation or
investigational product administration or may interfere with the interpretation of
study results and, in the judgment of the Investigator, would make the patient
inappropriate for entry into this study

9. Presence of neuropathy > Grade 1 per NCI CTCAE version 5.0

10. History of hypersensitivity to taxanes; hypersensitivity to the solvent does not
preclude patient participation in this study

11. Anticancer treatment, including endocrine therapy, radiotherapy (except stereotactic
brain surgery), chemotherapy, biologic therapy, or therapy in an investigational
clinical study, ≤ 14 days prior to the date of randomization

12. Major surgery ≤ 28 days prior to the date of randomization; patient must have complete
recovery from surgery

13. Less than 2 weeks or 5 plasma half-lives (whichever is greater) since last use of a
medication or ingestion of an agent, beverage, or food that is a known clinically
relevant strong inhibitor or known clinically relevant inducer of the cytochrome P450
(CYP) 3A pathway (patients should discontinue taking any regularly taken medication
that is a strong inhibitor or inducer of the CYP3A pathway)

14. History of hypersensitivity or unexpected reactions to capecitabine, other
fluoropyrimidine agents, or any of their ingredients

15. Known dihydropyrimidine dehydrogenase (DPD) deficiency. Testing for DPD deficiency
must be performed where required by local regulations, using a validated method that
is approved by local health authorities.

16. Pregnant or breastfeeding

17. If, in the opinion of the Investigator, the patient is deemed unwilling or unable to
comply with the requirements of the study

18. Treatment with brivudine, sorivudine, or its chemically-related analogs ≤ 28 days
prior to the date of randomization