Phase I study of bortezomib and oxaliplatin (BOX) in solid tumors: Improved neurotoxicity (NT) profile with lower bortezomib (B) dose

Abstract

12007 Background: B inhibits proteasome function and may be synergistic in causing apoptotic death with platinum agents. We were interested in combining B with OX but concerned with dose limiting (DL) NT based on our prior B phase I study [Hamilton et al., JCO 2005]: therefore this Phase I dose-escalation study (alternating increases of B and OX) focusing on NT was planned. Methods: Patients (pts) with metastatic solid tumors, PS 0–2, platinum or taxane naive, no peripheral neuropathy and adequate organ function, received B (D1, 4, 15, 18) and OX (D1, 15) every 28 days in a dose escalation design (see table ). Baseline and monthly assessments were performed by an independent neurologist. Results: 27 (18 gastrointestinal, 3 melanoma, 3 ovarian, 3 others) were accrued; pt characteristics: 14 male/13 female; median age 55 years (range 35–75); 2 median cycles (range 1–10). NT was not DL because it did not occur within the first cycle. Late and limiting NT was observed in levels 2–5 after 2–9 cycles, but serial neurologic evaluations showed reversible NT. With an amended new dose level to lower B to 1.0 mg/m2 (level 6) to avoid late NT, NT was not observed. Of 22 evaluable pts, there were 3 partial responses (ampullary, GE junction, biliary), 6 stable disease, and 13 disease progression by RECIST criteria. Conclusions: biweekly BOX is tolerable at B 1.0 mg/m2 and OX 85 mg/m2 with no DL NT. Additional observations on late NT are ongoing. This suggests B is a major contributor to NT observed in dose levels 2–5 and may potentiate the effects of OX. [Table: see text] [Table: see text]