Background: Most SCLC patients initially respond to chemotherapy but then relapse and die so new therapies are urgently required. Pre-clinical data shows statins induce growth arrest and apoptosis in SCLC and several other tumour cell types and are additive with chemotherapy. This may in part be due to impaired Ras superfamily function as statins deplete mevalonate, reducing geranylgeranylation and farnesylation of these proteins. We therefore undertook this large pragmatic phase III trial in order to determine if overall survival (OS) was affected by the addition of pravastatin in SCLC. Methods: Patients with limited (LD) or extensive (ED) stage SCLC were randomised to pravastatin 40mg OD or placebo for up to 2 years and given standard chemotherapy according to local practice recommended as either cisplatin 60mg/m² iv or carboplatin AUC 5 or 6 and etoposide 120 mg/m²iv d1 to 3 or 100 mg BD po d2 & 3; max 6 cycles plus radiotherapy as usually given. Patients were excluded if they had used statins within 12 months prior to randomisation. Stratification was: LD vs ED and ECOG 0,1 vs 2,3. Endpoints were: primary - OS; secondary - progression free survival (PFS), local PFS (local control), response rates (RR) and toxicity. Results: Between 2007 and 2012, 846 patients were randomised, 422 (49.9.%) received pravastatin and 424 (50.1%) placebo in 93 participating sites in the UK. The median age was 64 years (range 54-69); ECOG performance status: 0: 23%; 1: 54%; 2: 17% and 3: 6%; weight 72.6 kg; LD, 357 (42.2%); ED, 479 (56.6%); 211 (24.9%) had ipsilateral effusion and 201 (23.8%) had ipsilateral SCF lymph nodes; Relative Dose intensity of cisplatin/carboplatin and etoposide was 91.6% (range 80.8 to 99.7), and 94.7% (range 85.7 to 100); 83.4% vs 86.3% completed > 4 cycles of chemotherapy on the pravastatin and placebo arms respectively. Most patients completed 6 cycles of chemotherapy: 263 (62.3%) vs 265 (62.5%) in the pravastatin vs. placebo groups. Updated results showing OS, PFS, local PFS and toxicity will be presented. Conclusions: This trial will report on whether pravastatin 40 mg OD added to standard therapy alters the outcome for SCLC patients. Clinical trial information: ISRCTN56306957.