The primary objective of this pharmacokinetics study is to compare the maximum concentration level of paclitaxel in patients with low/sarcopenic skeletal muscle area (SMA), at the end of a 2-3 hour paclitaxel infusion, to the maximum level in patients with normal SMA at the end of a standard 1-hour infusion with the goal of determining whether lengthening the infusion in patients with low/sarcopenic SMA normalizes the levels to those of patients with normal SMA.

Paclitaxel is an FDA-approved and commonly used standard of care agent for patients with early-stage breast cancer. This study will use the standard dose of 80 mg/m^2, including the typical pre-medications as per University of Michigan Rogel Cancer Center institutional standard. The only investigational component of this study is lengthening the infusion duration from 1-hour to 2 or 3 hours for a single dose in patients with low SMA.

JAN2025 update, Paclitaxel is an FDA-approved and commonly used standard of care agent for patients with early-stage breast cancer or metastatic gastric or esophageal cancers.

Inclusion Criteria:

• Planned paclitaxel 80 mg/m^2, 1-hour infusion
• Evaluable computed tomography (CT) scan, positron emission tomography computed tomography (PET-CT) scan, or MRI scan (e.g. scan of the chest, abdomen, or pelvis for any indication w/in 1 year)
• Female
• ≥ 18 years old
• Adequate organ function to receive paclitaxel treatment as defined in the protocol
• Ability to understand and the willingness to sign a written informed consent

Exclusion Criteria:

• Concomitant administration of any moderate or strong inducer or inhibitor of CYP2C8, including rifampin or clopidogrel.
• History of hypersensitivity reaction to paclitaxel or any components of paclitaxel (e.g., Cremophor EL) that precludes continued treatment with standard dose and infusion length
• Pregnant or nursing
• Receiving any other dose (i.e., not 80 mg/m2) or infusion rate (i.e., not 60 minute infusion) either due to toxicity during a previous cycle or any other reason