Results from the biomarker-driven basket trial of RO5126766 (CH5127566), a potent RAF/MEK inhibitor, in RAS- or RAF-mutated malignancies including multiple myeloma.

2506Background: RO5126766 is a potent RAF and MEK inhibitor with activity in xenografts models of RAS and RAF-mutated cancers. We present data from the RAS/RAF-mutated advanced solid tumor cohort and the initial results for the multiple myeloma (MM) cohort. Methods: Patients with KRAS, NRAS or BRAF-mutant tumours were treated with RO5127566 using a novel schedule:4mg twice weekly in 4-week cycles. For MM patients, it was given 3 weeks out of 4 and co-administration of weekly dexamethasone was authorised. Response assessment was completed using RECIST 1.1 criteria for solid tumours and the International Myeloma Working Group (IMWG) criteria were used for MM. Results: A total of 20 patients with solid tumours (10 NSCLC, 5 gynaecological cancers and 5 miscellaneous cancers) and 1 MM patients were evaluable. Among the 10 KRAS-mutant NSCLC patients, tumour regression was seen in 6/10 (60 %), of which 3/10 (30 %) were partial responses. Two of these patients had maintained response for over 1 year and one patie...