Banoxantrone (AQ4N), a Tissue Targeted Prodrug: Results of a Phase 1 Study in Lymphomas.

AQ4N is a prodrug which is selectively bioreduced by cytochrome P450 to AQ4, a potent DNA intercalator and topoisomerase II inhibitor. Preclinical studies demonstrate AQ4N selectively targets lymphoblastoid cell lines and hypoxic tumors. This study assessed the maximum tolerated dose (MTD), and pharmacokinetics (PK) of repeated dosing of AQ4N in patients (pts) with lymphoid malignancies. AQ4N was administered IV on Day 1 of a 21 day cycle to cohorts of at least three pts at doses of 400, 800, or 1200 mg/m² for a maximum of 8 cycles. The dose was escalated as long as <33% of pts did not experience a dose limiting toxicity (DLT). 11 pts were enrolled with 3 pts treated at 400 mg/m² and 4 pts treated at 800 and 1200 mg/m² each. No pts experienced a DLT and no clinical MTD was identified. No further dose escalation was investigated due to reaching known maximum AQ4N solution solubility. The most common related adverse events (AE) observed were expected transient skin discoloration (100%), transient chromaturia (36%) and lymphopenia (27%), as well as fatigue (27%) and nausea (27%). AEs were primarily mild (Grade 1–2) with the exception of Grade 3 lymphopenias (n=3) and Grade 3 neutopenia (n=1) events. No dose reductions or dose delays resulted from these hematologic decreases. 6 pts experienced at least one serious AE, including: pneumonia, staph aureus bacteremia, acute respiratory distress syndrome (ARDS), dyspnea, and pleural effusion, none of which were attributed to AQ4N. The PK was linear over all doses studied. At 1200 mg/m² (n=4), the Day 1 AQ4N C_max was 122.3 ± 13.1 μg/mL, AUC_0–∞ was 340.8 ± 68.7 μg·h/mL, and T_1/2 was 3.2 h (range 2.8 to 4.1 h). One pt with follicular lymphoma dosed at 1200 mg/m² had a partial response after the 4^th cycle using the NHL standardized response criteria. The pt went on to complete all 8 cycles and to date remains in partial response. The bioreductive prodrug, AQ4N, is well-tolerated when administered on a repeated 21-day schedule at doses up to and including 1200 mg/m². Further dose escalation was precluded since the known maximum solubility of AQ4N was reached. Blood levels of AQ4N achieved in this study appear to be within the range of potentially therapeutic levels of the active drug, AQ4, as seen in previous preclinical and clinical studies of solid tumors (Harris PA et al, 2006; Albertella MR et al., 2006). Preliminary evidence of anti-tumor activity was seen in one pt with follicular lymphoma. Further clinical studies of AQ4N administered both as a monotherapy and in combination with chemo- and radiation therapy are planned in B-cell neoplasms and solid tumor malignancies.