1345P - Outcome of patients with elevated LDH treated with first-line targeted therapy (TT) or PD-1 based immune checkpoint inhibitors (ICI)

Elevated LDH is a known predictive and prognostic factor correlating with poor response rates and survival in patients (pts) with metastatic melanoma (MM) treated with targeted therapy (BRAF plus MEK inhibitors, TT) or immune checkpoint inhibitors (ICI). Whether TT or ICI in this subgroup of pts is more beneficial is unknown. Pts with MM and elevated LDH who started first-line therapy between March 2016 and June 2017 were retrospectively identified from 25 melanoma centers. The cohort was divided into 2 groups: pts receiving TT first-line (TT group) and ICI first-line (ICI group). Primary endpoints were overall response rate (ORR), progression-free survival (PFS), and overall survival (OS). Demographics and disease characteristics were also examined. 404 pts with elevated LDH at start of first-line systemic treatment (ST) received either TT (n=90, 22%) or ICI (n=314, 78%). TT included dabrafenib and trametinib (73%) and vemurafenib and cobimetinib (27%). ICI included pembrolizumab (47%), nivolumab (11%) and combination ipilimumab and nivolumab (40%). Median (med) follow-up time was 11.2 months (mo). Med age was 65 years, 58% male, ECOG ≥1 46%, AJCC stage M1c 45%, M1d 31%, >3 organ sites 57%, BRAF-mutant 43%. 71% had LDH 1-2x upper limit normal (ULN), 27% >2x ULN. Age, sex, ECOG and AJCC stage were similar in both groups. All TT pts had BRAF mutant MM, compared to 32% with ICI. Pts in the TT group were more likely to have >3 organ sites involved (71% vs 54%, p=0.003) or LDH >2x ULN (34% vs 24%, p=0.15) compared to ICI group. The TT group had superior ORR (63% vs 36%, p≤0.001) and PFS (med 4.7mo vs 2.3mo, p