A systematic review of immune checkpoint inhibitor (ICI) combinations suggests that they have a significant survival benefit over the tyrosine kinase inhibitor (TKI) sunitinib and should be made generally available to patients with advanced renal cell carcinoma (RCC).
Until recently, first-line therapy for RCC has primarily been TKIs that target vascular endothelial growth factor (VEGF) and other receptors, including sunitinib and pazopanib. Explorations of novel therapeutic regimens focused on the use of multiple TKIs in combination with monoclonal antibodies that directly inhibit VEGF and inhibitors of the mammalian target of rapamycin (mTOR), such as everolimus.
. VEGF and VEGF receptors inhibitors are believed to have immunomodulatory effects, including boosting immune cell infiltration as a result of their effect on tumor vasculature. That idea has spurred recent clinical trials that have examined ICIs in combination with VEGF-directed therapies.
In a study published online in Therapeutic Advances in Medical Oncology, researchers examined six phase 3 clinical trials. Each compared ICI combinations versus sunitinib as first-line therapy for advanced or metastatic RCC. Four of the studies tested TKI/ICI combinations, and one each tested an ICI/anti-VEGF antibody and dual ICIs.
After median follow-ups of 20-30 months, there was no benefit to PD-L1 inhibitor combinations (atezolizumab plus bevacizumab or avelumab plus axitinib) compared with sunitinib. Final survival analyses from one of the trials have not been reported yet.
PD-1 inhibitor combinations fared better. Nivolumab plus ipilimumab led to a 32% reduced risk of death in intermediate/poor-risk patients, compared with sunitinib, but the combination led to more frequent discontinuation because of toxicity (21.8% versus 12.3%). Nivolumab plus cabozantinib produced a 34% reduction in risk of death (P = .003) and a 48% reduction in risk of progression (P < .0001). Rates of discontinuation because of toxicity were similar to sunitinib.
Pembrolizumab combined with TKIs led to a 32% reduced risk of death (P = .003) and a 29% reduced risk of progression (P < .001). Pembrolizumab plus lenvatinib reduced risk of death by 28% (P value not reported) and the risk of progression by 61% (P < .001). Both combinations had a higher frequency of discontinuation because of toxicity (25.9% versus 10.1% and 37.2% versus 14.4%, respectively).
Given that there are no head-to-head comparisons between dual ICI or PD-1/TKI combinations, the researchers suggested that response outcomes may assist in selection between the two approaches. Overall, PD-1/TKI combinations had better overall response rates. The highest was seen in pembrolizumab plus lenvatinib, where frequency of progressive disease ranged from 5.4% to 11.3%. Complete response rate ranged from 8% to 10%.
The authors suggest that upfront treatment with a PD-1 inhibitor and a TKI could be appropriate for patients with a high tumor burden or aggressive disease, in whom stopping tumor growth is urgent and progression could be particularly worrisome.
Safety concerns associated with dual-ICI combination therapy was similar to that seen in RCC and other cancers. Dose delays, rapid diagnostic workups, appropriate timing, and the use of glucocorticoids were among strategies used to manage treatment-related adverse events.
The authors note that five combinations are approved by either the Food and Drug Administration or the European Medicines Agency for first-line treatment of metastatic RCC. Factors to consider for treatment selection include patient and disease characteristics, IMDC risk status, treatment history during earlier disease stage, and eligibility for immunotherapy. Nivolumab plus ipilimumab may be a good choice for patients with an intermediate or poor IMDC risk since it provides a strong and durable overall survival benefit. Pembrolizumab plus axitinib, pembrolizumab plus lenvatinib, and nivolumab plus cabozantinib all have good overall response rates and can prolong life, though extended TKI use can lead to chronic toxicity. Nivolumab plus ipilimumab is not approved for those with a favorable IMDC risk in many regions.
Four of the authors reported receiving honoraria, research funding, or consulting for a variety of pharmaceutical companies, including AbbVie, Astellas, Bayer, BMS, Eisai, Ipsen, Janssen, Merck, Novartis, Pfizer, Roche, and TerSera.