Pembrolizumab-axitinib combo improves survival even in poorer-risk RCC patients
First-line treatment with pembrolizumab plus axitinib significantly improved overall survival (OS) and progression-free survival (PFS) in patients with advanced clear-cell RCC* who had intermediate/poor IMDC** risk classification, according to updated results of the KEYNOTE-426*** study presented at BASCO 2019 Annual Meeting held in Singapore.
This open-label, phase III trial involved 861 patients with advanced clear-cell RCC who were randomized in a 1:1 ratio to receive either intravenous pembrolizumab 200 mg thrice/day for 35 cycles plus oral axitinib 5 mg twice/day (n=432) or oral sunitinib 50 mg once/day for the first 4 weeks of each 6-week cycle (n=429). Patients were stratified based on their IMDC risk into subgroups with favourable, intermediate, or poor risk, with risk scores of 0, 1 or 2, or 3–6, respectively. [BASCO 2019, abstract 4500; N Engl J Med 2019;380:1116-1127]
Of the 592 patients with IMDC intermediate/poor risk, those who received pembrolizumab + axitinib had higher OS (87 percent vs 71 percent, hazard ratio [HR], 0.52) and PFS rates (56 percent vs 40 percent, HR, 0.67) vs those treated with sunitinib alone at 12 months.
In addition, the objective response rate (ORR) of the IMDC intermediate/poor risk group treated with pembrolizumab + axitinib was almost double that of the patients treated with sunitinib alone (55.8 percent vs 29.5 percent).
On the other hand, the 12-month OS and PFS rates were comparable between the pembrolizumab + axitinib and sunitinib alone arms among those with favourable IMDC risk (n=269; 95 percent vs 94 percent, HR, 0.64 [for OS] vs 68 percent vs 60 percent, HR, 0.81 [for PFS]).
Notably, a higher ORR was observed among patients with favourable IMDC risk in the pembrolizumab + axitinib arm vs sunitinib alone arm at 12 months (66.7 percent vs 49.6 percent), “[which was] the most outstanding result [in this study],” said Dr Tay Miah Hiang from the Oncocare Cancer Centre in Singapore, who presented the study on behalf of the investigators.
Based on local pathology review, 105 participants had sarcomatoid RCC, of whom 51 were treated with pembrolizumab + axitinib (median age 58.0 years, 68.6 percent male) and 54 were given sunitinib only (median age 58.5 years, 70.4 percent male).
An improved OS and PFS was observed among patients with sarcomatoid feature in the pembrolizumab + axitinib group than the sunitinib alone group at 12 months (HR, 0.58 and HR, 0.54, respectively).
Patients with sarcomatoid features who were treated with pembrolizumab + axitinib also demonstrated an improved ORR than those on sunitinib alone (58.8 percent vs 31.5 percent), with a complete response rate of 13 percent in the pembrolizumab + axitinib arm vs 2 percent in the sunitinib alone arm, “which was much higher than the initial report in January,” Hiang noted.
“[Overall,] it shows that the percentage of tumour shrinkage was substantially greater with pembrolizumab plus axitinib vs sunitinib … The OS, PFS, and ORR benefit of pembrolizumab plus axitinib vs sunitinib was observed across all key subgroups,” Hiang said.
“Therefore, pembrolizumab plus axitinib is a new standard of care for the first-line therapy of advanced clear-cell RCC subtypes,” he added.
*RCC: Renal cell carcinoma
**IMDC: International Metastatic Renal Cell Carcinoma Database Consortium***KEYNOTE-426: A phase III randomized, open-label study to evaluate efficacy and safety of pembrolizumab (MK-3475) in combination with axitinib versus sunitinib monotherapy as a first-line treatment for locally advanced or metastatic renal cell carcinoma (mRCC)