REGorafenib vsTamoxifen in Patients With Platinum-sensitive OVARian Carcinoma and Isolated Biological Progression

• After surgery, most of patients with advanced ovarian/primitive peritoneal /fallopian carcinoma received as first line treatment, carboplatin plus paclitaxel plus or minus bevacizumab for 6 cycles followed by surveillance or bevacizumab maintenance therapy up to one year (GOG (Burger et al.), ICON7 (Perren et al.), French national guidelines Saint Paul de Vence (www.arcagy.org)).
• This multi-modality approach achieves clinical responses in about 70% of patients, although a majority of women eventually relapse and die from disease progression. The first sign of relapse can be a progressively rising CA-125 (Tuxen et al.).
• Biochemical-recurrent of Epithelial Ovarian Cancer (EOC) is defined as CA-125 elevation above normal values without clinical evidence of disease, and can predate clinical disease by approximately 3-6 months (Tuxen et al.). Even if CA-125 elevation is a harbinger of EOC relapse, the question remains as to whether early therapeutic intervention can translate into extending the duration of survival.
• A few years ago, Rustin reported from ovarian cancer patients on surveillance after first line treatment with isolated elevated CA-125 (without RECIST/symptoms criteria) that there was no benefit to initiate a new chemotherapy compared to surveillance (Rustin et al. Lancet 2010; Rustin et al. Ann Oncol 2011).
• For patients under bevacizumab on maintenance phase at the time of the CA-125 elevation without RECIST or symptoms progression, data are scare. In the GOG0218 trial, elevated CA-125 did not totally complied with RECIST criteria progression. This study reported that the median PFS is longer in patients with continuous bevacizumab (14.1 months), compared to patients under placebo (10.3 months), using CA-125 \& RECIST criteria, supporting the hypothesis that a maintenance treatment with an anti angiogenic agent allows delaying disease progression (Burger et al. N. Engl. J. Med. 2011). In an analysis of progression-free survival in which data for patients with increased CA-125 levels were censored, the median progression-free survival was 12.0 months in the control group but 18.0 months in the bevacizumab-throughout group (hazard ratio, 0.645; P<0.001). The relationship of CA-125 to progressive disease (PD) may be altered in bevacizumab (BV)-treated patients. In the Ocean trial elevated CA-125 was associated with forthcoming progression for the majority of the patients under bevacizumab (HR 0.48) in the platinum sensitive population (Aghajanian et al.).
• Current international recommendations are to continue the same strategy (surveillance or maintenance bevacizumab) until RECIST or symptomatic progression regardless of the CA-125 level.
• However, some can argue that a waiting attitude is deemed unacceptable due to patient anxiety over a rising CA-125 compelling a significant proportion of physicians to propose a therapeutic intervention, due to the nearness of the disease progression.
• Tamoxifen is an endocrine alternative treatment option in patients with rising CA-125. Hurteau et al. studies supported the use of tamoxifen showing a 17% response rate in measurable recurrent disease, 13% response rate in platinum resistant disease, observed stable disease in 38% of patients lasting a median of 3 months (Hatch, et al).
• The use of tamoxifen treatment as a control arm for isolated CA-125 is thus justified based on a favorable toxicity profile compared with available cytotoxic agents and the lack of interference with subsequent interventions beyond documentation of clinical progression (Marckman, et al). As patients have until today no benefit to introduce a new chemotherapy regimen for isolated elevated CA-125 (Rustin et al 2010), exploring new anti-angiogenic agent could be clinically relevant. Agents that inhibit tumor angiogenesis and invasion were considered to be ideal candidates for the experimental arm given their potential to prolong the duration of disease-free survival while exhibiting a more favorable toxicity profile than cytotoxic drugs.
• Pazopanib and other multi-kinase inhibitors such as cediranib, nintenanib reported activity in relapsing ovarian cancer (sensitive or resistant population) used alone in several phase II trials (Matulonis et al., Ledermann et al., and Friedlander et al.).
• Regorafenib is a new oral multi-kinase inhibitor. It inhibits kinases involved in angiogenesis (VEGFR 1-3, TIE 2), signaling in the tumor microenvironment (PDGFR-β, FGFR) and oncogenesis (KIT, RET and BRAF). Inhibition of tumor growth and formation of metastases were shown in vivo. Tumor activity has been reported in a variety of tumor types. Regorafenib is approved in Europe for the treatment of metastatic colorectal cancer in patients previously treated with, or who are not considered candidates for, available therapies. An application for GIST progressing after imatinib and sunitinib has obtained the AMM in Europe. The recommended dose is 160 mg taken once daily for 3 weeks followed by 1 week off therapy.

The objective of this randomized phase II is to evaluate the benefit of regorafenib for ovarian patients who reported a confirmed elevated CA-125 level under surveillance or bevacizumab, compared with tamoxifen.