Paclitaxel poliglumex (PPX) is a drug conjugate that links paclitaxel to poly-L-glutamic acid thereby increasing its radiation enhancement factor to 4.0–8.0 compared to 1.5–2.0 for paclitaxel. In previous phase I studies, The Brown University Oncology Group evaluated PPX with concurrent radiation and PPX/cisplatin/RT. A phase II study was subsequently performed to evaluate the pathologic response rate of neoadjuvant PPX, cisplatin, and radiation for patients with esophageal cancer.
Eligible patients had pathologically confirmed adenocarcinoma or squamous cell carcinoma of the esophagus or GE junction with no evidence of distant metastasis. Patients received weekly PPX 50 mg/m2 and cisplatin 25 mg/m2 for 6 weeks with concurrent 50.4 Gy of radiation. Six to eight weeks after completion of chemoradiotherapy, patients underwent surgical resection.
The study has completed accrual of 40 patients, 37 with adenocarcinoma and 3 with squamous cell cancer. The median age is 62 years. Toxicity data are available for the first 35 patients. Four of 35 patients experienced grade 4 non-hematologic toxicities, which included electrolyte abnormalities, glucose intolerance, hypersensitivity reaction, and thromboembolus. Eleven of 35 patients had grade 3 non-hematologic toxicities including electrolyte abnormalities (n=5), nausea (n=3), dysphagia (n=2), fatigue (n=2), glucose intolerance (n=2), and hypersensitivity reaction (n=1). Grade 3 anorexia was reported in only 1 patient who subsequently was given TPN. No patients required a feeding tube. There were no grade 4 hematologic toxicities; grade 3 hematologic toxicities included neutropenia (n=2) and anemia (n=1). Of the first 28 patients undergoing surgery, all with adenocarcinoma, 7 of 28 (25%) have had a pathologic complete response.
PPX, cisplatin and concurrent radiation is a well tolerated, easily administered regimen for esophageal cancer with a very low incidence of significant esophagitis and a promising pathologic complete response rate consistent with the preclinical data of PPX and radiation.