Once weekly paclitaxel associated with a fixed dose of oral metronomic cyclophosphamide: a dose-finding phase 1 trial

The primary aim of this trial was to determine the recommended phase II dose (RP2D) of weekly paclitaxel (wP) administered in combination with oral metronomic cyclophosphamide (OMC).

Patients ≥ 18 years of age with refractory metastatic cancers were eligible if no standard curative measures existed. Paclitaxel was administered IV weekly (D1, D8, D15; D1 = D28) in combination with a fixed dose of OMC (50 mg twice a day). A 3 + 3 design was used for dose escalation of wP (40 to 75 mg/m²) followed by an expansion cohort at RP2D. Dose-limiting toxicity (DLT) was defined over the first 28-day cycle as grade ≥ 3 non-hematological or grade 4 hematological toxicity (NCI-CTCAE v4.0) or any toxicity leading to a dose reduction.

In total, 28 pts. (18 in dose-escalation phase and 10 in expansion cohort) were included, and 16/18 pts. enrolled in the dose-escalation phase were evaluable for DLT. DLT occurred in 0/3, 1/6 (neuropathy), 0/3 and 2/4 pts. (hematological toxicity) at doses of 40, 60, 70 and 75 mg/m² of wP, respectively. The RP2D of wP was 70 mg/m²; 1/10 patients in the expansion phase had a hematological DLT. At RP2D (n = 14), the maximal grade of drug-related adverse event was Gr1 in three patients, Gr2 in six patients, Gr3 in one patient and Gr4 in one patient (no AE in three patients). At RP2D, a partial response was observed in one patient with lung adenocarcinoma.

The combination of OMC and wP resulted in an acceptable safety profile, warranting further clinical evaluation.

TRN: NCT01374620 ; date of registration: 16 June 2011.