Final report of a phase I study of 2-hydroxyoleic acid (2OHOA) a novel sphingomyelin synthase activator in patients (pt) with advanced solid tumors (AST) including recurrent high grade gliomas (rHGG).

Abstract

2554 Background: 2OHOA is an orally bioavailable, first-in-class synthetic hydroxylated fatty acid, that activates SGMS1 and modulates the lipid content of cancer cell membranes. This regulates the localization of key signaling proteins, including Ras and PKC at the plasma membrane, leading to inactivation of Ras/MAPK, PI3K/Akt and PKC/cyclin/CDK signaling pathways. A dose escalation (DE) and partial expansion cohorts (EC) results of the phase 1 study have previously been reported. We now present the final results of the study. Methods: 2OHOA was evaluated in a 3+3 DE design (7 cohorts from 500mg/d to 16000mg/d) and 2 EC at 4000mg TID in 21 days cycles. PK profiles were determined after single dose (fasted [D-7] or fed [D1]) and multiple doses (fed [D21]) during DE phase and only on D1 throughout EC.Safety assessments were based on CTCAEv4.Tumor response was measured by RECIST and RANO every 6 weeks. Results: Overall 54 pt (DE: 32 pt; 21AST/11rHGG; EC: 22 pt; 12 AST/10 rHGG) were treated (median age 60, range 19-78 years). During the EC the most common treatment related G1-G2 toxicities were diarrhea (n = 13;11pt),nausea (n = 7;6pt), ALT increase (n = 6;4pt), pruritus in throat (4pt), fatigue (4pt) and vomiting (3pt). No G3-G4 toxicities or DLTs were reported confirming the MTD from the DE at 4g TID. Food intake did not alter oral 2OHOA bioavailability. Steady state was already achieved at D8. Power model showed dose proportionality in terms of AUC and Cmax, after single and multiple BID dosing. Average t1/2 ranged from1-2h to 8-12h with delayed Tmax and longer half-lives at higher doses. One glioblastoma (GBM) pt had sustained partial response ( > 2,5 years) and 4rHGG pt (3 GBM) achieved stable disease for at least 6 months. They had previously received 2 lines of treatment without bevacizumab. Tumor markers were measured and will be presented. Conclusions: 2OHOA is well tolerated at the P2RD of 4000mg TID PO daily. The preliminary antitumor activity including a sustained PR in heavy pretreated rHGG pt warrants further investigation in a Ph2 study Clinical trial information: NCT01792310.