Phase I dose and schedule finding study of pegylated liposomal doxorubicin (D) and weekly docetaxel (T)
12012 Background: The combination of D and T has many potential applications, particularly in breast and ovarian cancers. A phase 3 trial is examining D + T versus T in first-line metastatic breast cancer ( NCT00091442 ). D has better tumor localization and penetration in solid tumors than conventional doxorubicin. In previous studies, the maximum tolerated dose (MTD) of the combination was identified as D 30 mg/m2 and T 75 mg/m2 q4 weeks (wks), with a recommended dose and schedule of D 30 mg/m2 and T 60 mg/m2 q3wks without G-CSF. We conducted a phase I study to determine the MTD of D with weekly T. Our hypothesis was that the lower incidence of myelosuppression with weekly T would allow for higher doses of both drugs. Methods: There were 2 schedules. Arm A: D q4wks starting at 25 mg/m2 with weekly T for 3 wks starting at 30 mg/m2. Arm B: D q2wks starting at 15 mg/m2 with weekly T for 3 wks starting at 30 mg/m2. One cycle was 28 days. Standard 3+3 design was used with MTD defined as the highest dose level causing dose limiting toxicity (DLT) in ≥ 2/6 patients (pts). Results: 32 pts were treated; 13 females, 19 males, median age of 60 years. Median number of cycles administered was 2 (1–13) with a median follow-up of 11.5 months. Tumor types included lung (16%), thyroid (9%), esophagus (9%), nasopharynx, breast, colorectal, stomach and kidney (6% each). Arm A (13 pts) was closed after 2/7 evaluable pts at dose level 2 (D 33mg/m2; T 30 mg/m2) experienced DLT in the form of grade 3 stomatitis. The most common grade 3/4 toxicities were neutropenia (3/13), stomatitis (3/13) and fatigue (3/13). Arm B accrued 19 pts. The trial was closed at the highest planned dose in Arm B (D 20mg/m2 q2wks and T 35 mg/m2 weekly) with only 1/6 evaluable pts experiencing DLT in the form of grade 4 fatigue and weakness. The most common grade 3/4 toxicities in Arm B included neutropenia (5/19 pts), fatigue (5/19 pts) and stomatitis (2/19 pts). There was no grade 3/4 hand-foot syndrome or cardiotoxicity. 2 partial responses were observed in nasopharyngeal and salivary gland carcinomas, with 13 pts achieving stable disease. Conclusions: The combination of D q2 wks and T weekly for 3/4 wks is well tolerated and results in a higher dose intensity of both drugs than in previously evaluated regimens. [Table: see text]