Dr Shroff on the Addition of Nab-Paclitaxel to Gemcitabine/Cisplatin in Biliary Tract Cancer

“Response is a meaningful thing in biliary tract cancers, especially to try to preserve liver function. The overall response rate was actually…statistically significantly higher in patients who received [the triplet], and the disease control rate was also statistically significantly higher.”

Rachna Shroff, MD, MS, FASCO, interim clinical affairs director, associate director, Clinical Investigations, co-lead, Gastrointestinal Clinical Research Team, The University of Arizona Cancer Center; and professor, Department of Medicine, chief, Division of Hematology/Oncology, medical director, Oncology Service Line, associate dean, Clinical and Translational Research, The University of Arizona College of Medicine, discusses key findings from the phase 3 SWOG S1815 trial (NCT03768414) evaluating the addition of nab-paclitaxel (Abraxane) to gemcitabine and cisplatin in patients with newly diagnosed, advanced biliary tract cancer.

The phase 3 study evaluating the triplet regimen vs gemcitabine and cisplatin alone in patients with biliary tract cancers did not demonstrate a statistically significant improvement in median overall survival (OS) with the triplet, though a numerical advantage was observed, Shroff begins. Among efficacy-evaluable patients (n = 441), the median OS was 14.0 months (95% CI, 12.4-16.1) with the triplet compared with 13.6 months (95% CI, 9.7-16.6) with gemcitabine and cisplatin alone (HR, 0.91; 95% CI, 0.72-1.14; P = .41). The median progression-free survival was also comparable between the 2 groups at 7.5 months (95% CI, 6.4-8.5) with nab-paclitaxel plus gemcitabine and cisplatin vs 6.3 months (95% CI, 4.4-8.2) with gemcitabine and cisplatin alone (HR, 0.89; 95% CI, 0.71-1.12; P = .32).

However, the triplet regimen led to a significantly higher overall response rate of 31% vs 21% with gemcitabine and cisplatin alone (P = .03), as well as a higher disease control rate of 78% vs 67%, respectively (P = .03), Shroff reports. These findings suggest a potential benefit in tumor response with the triplet, which may be clinically relevant in preserving liver function, particularly in intrahepatic cholangiocarcinoma, she explains.

Exploratory subgroup analyses indicated potential signals of benefit in certain patient populations, Shroff notes. Among patients with gallbladder cancer, the median OS was 17.0 months (95% CI, 11.3-20.7) with the triplet vs 9.3 months(95% CI, 6.0-12.5) with gemcitabine plus cisplatin alone. Similarly, in patients with locally advanced disease, the median OS was 19.2 months (95% CI, 16.3-24.3) with the triplet vs 13.7 months (95% CI, 8.8-21.8) with gemcitabine plus cisplatin alone. Although these findings suggest a possible advantage with the triplet in these subgroups, they remain exploratory and require prospective validation in larger studies to determine clinical significance, she concludes.