SUMMARY: ColoRectal Cancer (CRC) is the third most common cancer diagnosed in both men and women in the United States. The American Cancer Society estimates that approximately 140,250 new cases of CRC will be diagnosed in the United States in 2018 and about 50,630 patients are expected to die of the disease. The lifetime risk of developing CRC is about 1 in 21 (4.7%). Even though colon cancer localized to the bowel is potentially curable with surgery and adjuvant chemotherapy, advanced colon cancer is often incurable. STIVARGA® (Regorafenib), is an oral multi-kinase inhibitor and inhibits multiple kinases including VEGF1, VEGF2, VEGF3, PDGFR, FGFR involved in tumor angiogenesis and KIT, RET, RAF-1, BRAF involved in oncogenesis. STIVARGA® is approved by the FDA for the treatment of patients with metastatic CRC, who have progressed on 5FU, ELOXATIN® (Oxaliplatin), CAMPTOSAR® (Irinotecan), anti-VEGF and anti-EGFR therapies, at a dose of 160 mg orally, once daily for the first 21 days of each 28-day cycle. The approval was based on a phase III trial in which patients receiving STIVARGA® had a statistically significant improvement in the Overall Survival (OS) and Progression Free Survival (PFS), compared to placebo.
The starting dose of STIVARGA® has been an obstacle and toxicities such as Palmar-Plantar Erythrodysesthesia Syndrome (PPES) commonly occurring during the first 2 weeks, as well as fatigue and hypertension have limited its use. Various dosing schedules have been implemented into clinical practice, despite the absence of reliable supportive data. There is therefore a need to optimize the dose of STIVARGA® in patients with refractory mCRC to maintain efficacy, while improving the tolerability profile. CORRELATE study looked at the data from the real-world setting of refractory mCRC regarding the dosing of STIVARGA® and safety, whereas the ReDos study evaluated a dose-escalation strategy, starting with a lower dose of STIVARGA®.
CORRELATE is a prospective, international observational study conducted in 13 countries to evaluate the use STIVARGA® in a real-world setting, based on safety and efficacy. The primary objective of this study was to assess safety. This final analysis describes the real-world dosing of STIVARGA® in mCRC.
Of the 1037 patients included in this study, 57% started treatment at 160 mg, 30% at 120 mg, and 13% at 80 mg or less. The mean dose administered was 75% of the approved dose. The median patient age was 65 years and majority of the patients had an ECOG performance status (PS) of 0-1 (87%). Dose reductions were more frequent in the 160 versus 120 mg group and treatment modifications were most commonly due to treatment related adverse events (66%). Most treatment discontinuations (49%) were due to radiologic disease progression, whereas 19% were due to STIVARGA® related adverse events. Treatment related adverse events of any grade occurred in 95% of patients, and 80% were attributed to STIVARGA®. Median overall survival (OS) was 7.6 months and the estimated 1-year OS was 34%.
It was concluded from this real-world, observational study that the starting dose of STIVARGA® for nearly half of patients was less than 160 mg/day and the common treatment related adverse events were generally consistent with the known safety profile of STIVARGA® in mCRC. Despite the dose modifications of STIVARGA®, there was no significant impact on its efficacy in terms of the median OS and median PFS.
ReDOS is a randomized phase II study in which STIVARGA® dose-escalation strategy beginning at a lower starting dose of 80 mg daily and ending at 160 mg daily was compared with the standard dose, in patients with refractory mCRC. In this dose escalation study, patients in Arm A (N=54) received STIVARGA® 80 mg daily, with weekly dose escalation up to 160 mg daily, if no significant drug-related toxicities were experienced, where as in Arm B (N=62), patients received the standard dose of STIVARGA® 160 mg daily, for 21 days of a 28-day cycle. The median age was 61 years and both treatment groups were well balanced. The Primary endpoint was the proportion of patients who completed 2 cycles of treatment and initiated the 3rd cycle if there was no progression.
The study met its primary endpoint with 43% of patients on Arm A initiating the 3rd cycle versus only 25% of patients on Arm B (P=0.028). The median Overall Survival (OS) was improved in Arm A versus Arm B (9 months versus 5.9 months ; P=0.094). The median Progression Free Survival (PFS) was 2.5 months for Arm A and 2 months for Arm B (P=0.55). Overall grade 3 and 4 toxicities were lower on Arm A versus Arm B and multiple Quality Of Life parameters were improved in Arm A versus Arm B, at week 2 of the first cycle.
It was concluded that weekly dose escalation of STIVARGA® from 80 mg to 160 mg daily was superior to a starting dose of 160 mg daily. Based on this study, the NCCN has updated its ColoRectal Cancer (CRC) guidelines, recommending a weekly STIVARGA® dose-escalation strategy beginning at 80 mg and ending at 160 mg, for previously treated patients with metastatic ColoRectal Cancer.
Real-world dosing of regorafenib (REG) in metastatic colorectal cancer (mCRC): final results from the prospective, observational CORRELATE study. O'Connor JM, Ducreux M, Petersen LN, et al. Ann Oncol. 2018;29 (suppl_8): viii150-viii204. 10.1093/annonc/mdy281
Regorafenib dose optimization study (ReDOS): Randomized phase II trial to evaluate dosing strategies for regorafenib in refractory metastatic colorectal cancer (mCRC)-an ACCRU Network study. Bekaii-Saab TS, Ou FS, Anderson DM, et al. J Clin Oncol. 2018;36(suppl 4S; abstr 611)
