Effect of ipilimumab at 10 mg/kg on disease control in patients (pts) with M1c-stage melanoma in relation to baseline lactate dehydrogenase (LDH) levels

Abstract

9041 Background: Ipilimumab, a fully human, anti-cytotoxic T-lymphocyte antigen-4 monoclonal antibody, enhances antitumor immunity. Ipilimumab is clinically active in advanced melanoma, with a 1-year survival rate of ∼50% in Phase II studies (Wolchok et al. CRI-CVC annual meeting 2008. Oral presentation). Serum LDH level is an independent prognostic factor for malignant melanoma, and is strongly predictive of reduced survival in stage IV disease (Bedikian et al. J Clin Oncol. 2006;24:4738–4745.). This analysis evaluated the association between baseline LDH levels and disease control (stable or reduced measurable tumor burden) in previously treated pts with M1c-stage melanoma (metastasis to vital organs other than the lungs) who received ipilimumab in 2 recently completed Phase II studies (CA184008 and 022). Methods: Ipilimumab at 10 mg/kg was given every 3 weeks (Q3W) × 4; eligible pts could continue to receive ipilimumab Q12W beginning at Week 24. In study 022, pts were randomized to receive ipilimumab induction dosing at 0.3, 3.0, or 10 mg/kg Q3W × 4; study 008 was a single- arm trial of ipilimumab at 10 mg/kg. Disease control data were pooled from the 2 Phase II studies for pts treated with ipilimumab at 10 mg/kg and stratified by normal and elevated (>1× upper normal limit [UNL]) LDH levels. Elevated LDH was not capped. Results: For 227 pts treated at 10 mg/kg, 123 had M1c-stage disease: 42 had normal LDH and 81 had LDH >1 × UNL (of which 32 had LDH 2 × UNL). Among these 123 pts, 17/81 (21.0%) [95% CI 12.7–31.5] with elevated LDH levels experienced disease control, whereas 12/42 (28.6%) [95% CI 15.7–44.6] with LDH levels at or below the UNL experienced disease control. Conclusions: Our data show that ipilimumab exerts similar disease control in pts with normal and elevated LDH levels. Ipilimumab therefore appears to have clinical activity in the form of disease control in pts with a very poor prognosis, i.e., M1c-stage melanoma and elevated LDH levels. [Table: see text]