Activity of cabozantinib (XL184) in hepatocellular carcinoma patients (pts): Results from a phase II randomized discontinuation trial (RDT).
261 Background: Cabozantinib is an oral, potent inhibitor of MET and VEGFR2. MET over-expression has been observed in advanced hepatocellular carcinoma (HCC). Anti-VEGF pathway agents have shown clinical benefit in pts w/ HCC. Simultaneous targeting of the MET and VEGF signaling pathways with cabozantinib may therefore be a promising treatment strategy. Methods: HCC pts with progressive measurable disease, per mRECIST received cabozantinib at 100 mg qd PO over a 12 week Lead-in period. Up to one prior regimen was allowed and only pts with Child-Pugh score of A were eligible. Tumor response was assessed every 6 weeks. Treatment beyond Week 12 was based on response: pts with PR continued open-label cabozantinib, those with SD were randomized to cabozantinib vs. placebo, and those with PD discontinued study drug. The primary endpoint was overall response rate (RR) per mRECIST in the Lead-in period, and progression free survival for pts who entered the randomized period. Results: Enrollment has been completed with 41 pts. Results are available for 34 pts. Median age: 61 years (33 to 83). Males: 24/34 (71%). Asian: 13/34 (38%). HCC etiology: Hepatitis B or C 12/34 (35%); alcohol abuse 5/34 (15%); other 17/34 (50%). Extrahepatic spread was observed in 21/34 (62%). The median number of prior systemic treatments was 1; prior sorafenib: 16/34 (47%). Most common related AEs ≥Grade 3 were hand-foot syndrome (15%), diarrhea (9%) and thrombocytopenia (9%). 3/33 pts evaluable for tumor assessment at 12 weeks achieved PR by original RECIST (RR 9%). One additional pt randomized at Week 12 achieved PR at 18 weeks and treatment remains blinded on study for >1 year. 24/30 pts (80%) with ≥1 post-baseline scan had tumor regression (with no apparent relationship to prior sorafenib therapy). The overall disease control rate (DCR = PR+SD) at Week 12: 71% (Asian subgroup: 77%). Median time on study: 6 mos (1 to 15+ mos). AFP responses (defined as reduction from baseline of >50%) in 21 pts with ≥1 post-baseline result: 9/21 (43%). Conclusions: Cabozantinib exhibits clinical activity in HCC pts with advanced disease, regardless of prior sorafenib treatment as reflected by tumor reduction, high DCR and time on study.