[18F]Fluorothymidine (FLT) PET/CT Imaging In Rb+ Metastatic Breast Cancer Patients Undergoing LEE011 And Weekly Paclitaxel Therapy

Inclusion Criteria:

- At least 18 years of age

- History of histologically or cytologically confirmed breast cancer, any ER, PR or HER2
status is allowed as long as it expresses the Rb protein.

- At least one site of metastatic breast cancer that is outside of the liver and bone
that is identified by standard imaging (e.g. CT, MRI, FDG PET/CT, ultrasound, x-ray)
and is measurable as defined by RECIST 1.1

- Participants must be informed of the investigational nature of this study and provide
written informed consent in accordance with institutional and federal guidelines prior
to study-specific procedures.

- Patients must be candidates to receive treatment on the therapeutic trial UPCC06115, a
Phase I study of ribociclib (LEE011) and weekly paclitaxel.

Exclusion Criteria:

- Females who are pregnant at the time of screening will not be eligible for this study,
urine pregnancy test will be performed at screening in women of child-bearing
potential.

- Inability to tolerate imaging procedures in the opinion of an investigator or treating
physician

- Serious or unstable medical or psychological conditions that, in the opinion of the
investigator, would compromise the subject's safety or successful participation in the
study.

- Ineligible for the therapeutic trial UPCC 06115 Only individuals (aged 18 or over) who
can understand and give informed consent will be eligible to participate in this
study. Individuals who are considered to be mentally disabled will not be recruited
for this study. All subjects must be able to give informed consent. We will not be
using specific methods to assess decisional capacity. Economically disadvantaged
persons will not be vulnerable to undue influence, patients will be informed that
participation is voluntary. All individuals will be told that their choice regarding
study participation will in no way change their access to clinical care. This should
negate any undue influence or coercion. Children, fetuses, neonates, or prisoners are
not included in this research study. It is unlikely that the researchers will
encounter a patient/study participant who is pregnant during enrollment because
pregnant patients may not enroll on the parent treatment protocol, UPCC06115. However,
menopausal status of the study participant will be reviewed during the screening
process by examining the patient's medical record; women of child-bearing potential
will have a urine pregnancy test at the time of screening.