Open-label extension study of the RNAi therapeutic ALN-VSP02 in cancer patients responding to therapy.
Maria Alsina, MD
Background: ALN-VSP02 is an RNA interference (RNAi) therapeutic comprised of lipid nanoparticle-formulated small interfering RNAs targeting vascular endothelial growth factor (VEGF)-A and kinesin spindle protein (KSP). In a phase 1 trial, ALN-VSP02 administered as an iv infusion q2 wks was well-tolerated and showed evidence of anti-VEGF pharmacology and antitumor activity.
Methods: Patients treated on the phase I trial with stable disease (SD) or better after 4 months (8 doses) were eligible to continue on an extension study until disease progression. Main objectives included continued evaluation of safety/tolerability and assessment of disease response.
Results: Seven of 37 patients (18.9%) evaluable for response went onto the extension study, including 1 of 7 (14.2%) at 0.4 mg/kg, 2 of 5 (40%) at 0.7 mg/kg, and 4 of 11 (36.3%) at 1.0 mg/kg. All had progressed after one or more prior therapies. Tumor types included head and neck squamous cell carcinoma, angiosarcoma, endometrial cancer, renal cell carcinoma (RCC, N=2), and pancreatic neuroendocrine tumor (PNET, N=2). At the time of enrollment, 6 had SD and one (endometrial cancer with multiple liver metastases) had an unconfirmed partial response (PR). The average length of time on treatment (including phase I and extension studies) was 9.5 months (range 5-19). As of January 2012, 3 patients remain on study, including the endometrial cancer patient with an ongoing PR who has had >80% tumor regression after 19 months of treatment at 0.7 mg/kg and two patients with RCC and PNET with continued SD after nearly 1 year of treatment at 1.0 mg/kg. The other patients with RCC and PNET at 1.0 mg/kg with SD came off after 8.5 and 5.5 months, respectively, for adverse events that included fatigue or elevated alkaline phosphatase. A decrease in spleen volume, likely an on-target effect and not associated with any adverse events, occurred to a greater degree on the extension study than on the phase I trial and was most pronounced in patients receiving ≥ 12 doses.
Conclusions: ALN-VSP02 has preliminary activity against endometrial cancer, RCC and PNET and a favorable safety profile that permits chronic dosing. Phase II trials are warranted in these and other VEGF-overexpressing tumors.