Abstract
Keywords
Introduction
Kidney cancer is a common malignancy with over 430,000 new cases reported worldwide in 2020 resulting in approximately 180,000 deaths. 1 Renal cell carcinoma (RCC) represents the majority of kidney cancers (90–95%), with clear-cell RCC being the most common histological subtype.2,3 Approximately 30% of RCC cases are diagnosed at the advanced or metastatic stage and close to 80% of these patients have intermediate or poor-risk disease as per the International Metastatic renal cell carcinoma Database Consortium (IMDC) criteria.2–4 RCC is typified by inactivation of the von Hippel–Lindau tumor suppressor gene leading to high expression of the proangiogenic vascular endothelial growth factor (VEGF).5–7
Until recently, the mainstay of first-line therapy for advanced RCC involved the inhibition of angiogenesis with tyrosine kinase inhibitors (TKIs) against multiple receptors including those of VEGF (e.g. sunitinib and pazopanib).8–10 Historical benchmarks for median overall survival (OS) in the VEGF-targeted therapy era by IMDC risk groups have been 43, 23, and 8 months for favorable (IMDC 0), intermediate (IMDC 1 or 2), and poor-risk patients (IMDC ⩾3), respectively. 11 For years, the research landscape typically involved multiple alternative TKIs that also inhibit VEGF receptors including axitinib, cabozantinib, and lenvatinib,12–14 a monoclonal antibody (MoAb) that directly inhibits the function of VEGF (bevacizumab) 15 and inhibition of the mammalian target of rapamycin (everolimus). 16
Immune checkpoint inhibitors (ICIs) include cytotoxic T lymphocyte antigen 4 inhibitors (e.g. ipilimumab) and those against the programmed cell death protein 1 (PD-1) in peripheral tissues (e.g. nivolumab and pembrolizumab) or its ligand (PD-L1) (e.g. atezolizumab and avelumab), some of which have recently become preferred for most first-line treatment of RCC.17–23 Therapies directed at VEGF or its receptor (VEGF-directed, anti-angiogenic monoclonal antibodies or TKIs) are thought to have immunomodulatory effects including the enhancement of immune cell infiltration by normalizing tumor vasculature holding the promise of synergistic activity.24–26 In the last 3 years, results from multiple phase III trials assessing the first-line benefits of ICI combinations involving dual ICIs or ICIs in combination with VEGF-directed therapies have become available. This review will consider the safety and efficacy of these regimens in newly diagnosed advanced RCC and provide practical clinical guidance on their use in this setting.
Methods
A search of published and presented literature was conducted to identify phase III trials with outcomes assessing ICI combination regimens in RCC. PubMed (all time to 19 March 2022), the proceedings from the 2019, 2020, and 2021 American Society of Clinical Oncology (ASCO) and the European Society for Medical Oncology (ESMO) annual meetings as well as the ASCO Genitourinary Cancers Symposium were searched using the key search terms ‘immune checkpoint inhibitors’ AND ‘renal cell carcinoma’, AND ‘advanced’ OR respective aliases. A supplemental bibliographic search of review articles and pooled/meta-analyses was also conducted. In addition, directed searches were performed after the database search cutoff date to ensure that the most up-to-date reports of eligible studies were considered.
English language records were vetted at abstract level and confirmed at full text as needed. Excluded studies included those that were non-original research, preclinical, correlative science, not specific to RCC, in early stages of disease, retrospective, prospective phase I, II, IIIb, IV trials, or undefined phase, without outcomes as well as addressing non-systemic therapy combinations, and duplicate or prior reports.
Findings
The literature search identified a total of 628 records, resulting in a total of six eligible phase III trials (Preferred Reporting Items for Systematic Reviews and Meta-Analyses, Figure 1).27–32

Preferred Reporting Items for Systematic Reviews and Meta-Analyses diagram.
First-line ICI combinations
Six phase III trials assessed ICI combinations as first-line systemic treatment of advanced or metastatic RCC compared with the control arm of sunitinib (Table 1).27–32 One evaluated a dual ICI combination, 30 another an ICI and anti-VEGF MoAb combination, 32 and four ICI plus TKI combinations.27–29,31
Phase III trials assessing efficacy of first-line ICI combinations in advanced RCC. IRC assessed the efficacy of outcomes in intent-to-treat populations of phase III ICI combination trials in previously untreated advanced RCC summarized and ordered by date of first report of results from initial analysis. Outcomes in specific IMDC risk populations were described when used in the primary endpoint analyses. Outcomes in PD-L1-positive subgroups summarized in text only.
Co-primary endpoint was investigator-assessed PFS in the PD-L1-positive population (median, 11.2
At a median follow-up of 15 months.
IRC assessed at a minimum follow-up of 13 months.
Co-primary endpoints were IRC-assessed PFS and OS in the PD-L1-positive population (median, 13.8
At the earlier follow-up of 18.1 months.
BID, twice daily; CI, confidence interval; CPS, combined positive score; DX, day X; HR, hazard ratio; IC, tumor-infiltrating immune cells; ICI, immune checkpoint inhibitor; IMDC, International Metastatic Renal Cell Carcinoma DATABASE Consortium; IRC, independent review committee; IV, intravenous;
CheckMate 214 randomized 1096 patients of all risk groups 1:1 to receive nivolumab plus ipilimumab compared with sunitinib, with co-primary endpoints of OS, independent review committee (IRC)-assessed progression-free survival (PFS) and objective response rate (ORR) in IMDC intermediate and poor-risk patients (intermediate/poor risk,
Safety outcomes from clinical trials assessing first-line ICI combinations in metastatic RCC.
AEs, adverse events; ALT, alanine aminotransferase; AST, aspartate aminotransferase; IO, immunotherapy;
IMmotion151 randomized 915 patients with RCC and predominantly a clear-cell component (92%) 1:1 to receive atezolizumab plus bevacizumab compared with sunitinib. At median follow-ups of 15 and 24 months for PFS and OS, respectively, similar investigator-assessed ORRs and DoRs were observed between arms, with no statistically significant improvements seen in PFS or OS for the ICI plus VEGF-directed therapy combination compared with sunitinib.
32
At a longer median follow-up of 32 months, no significant improvement in the co-primary endpoint of OS was seen in ITT patients (median OS, 36.1
JAVELIN Renal 101 randomized 886 patients 1:1 to receive avelumab plus axitinib compared with sunitinib in patients with primarily PD-L1-positive tumors (63.2%). Co-primary endpoints were IRC-assessed PFS and OS among patients with PD-L1-positive tumors. With a minimum follow-up of 13 months, significant IRC-assessed PFS improvements were observed for the ICI combination over sunitinib in patients with tumors overexpressing PD-L1 and ITT patients, with a near doubling of ORRs and median DoRs not reported (Table 1).
27
At a minimum follow-up of 28 months, there was no statistically significant OS improvement for the ICI combination over sunitinib (median OS, NE
KEYNOTE-426 randomized 861 patients 1:1 to receive the PD-1 inhibitor pembrolizumab plus axitinib compared with sunitinib. With a median follow-up of 30.6 months in the ITT population, statistically significant improvements for the ICI combination
CheckMate 9ER randomized 651 patients 1:1 to receive the PD-1 inhibitor nivolumab plus cabozantinib compared with sunitinib. With a median follow-up of 18.1 months, statistically significant benefits were seen in the primary endpoint of IRC-assessed PFS for nivolumab plus cabozantinib
CLEAR randomized 1069 patients 1:1:1 to receive pembrolizumab or everolimus plus lenvatinib, with both combinations compared with sunitinib. At a median follow-up of 26.6 months, the primary endpoint of IRC-assessed PFS statistically significantly favored both the pembrolizumab (median PFS, 23.9
Discussion
What is the clinical benefit of ICI combination therapy in the first-line treatment of advanced RCC?
Preferred approaches for the first-line treatment of advanced RCC have shifted from TKI monotherapy, such as sunitinib or pazopanib, to combination strategies for most patients.9,10 Six phase III trials evaluating ICI combinations compared to sunitinib have been reported, including one assessing a dual ICI combination 30 and five assessing combinations of an ICI plus an anti-angiogenic agent using either a MoAb 32 or a TKI.27–29,31 At median follow-ups of approximately 20–30 months, neither of the PD-L1 combinations, atezolizumab plus bevacizumab from IMmotion151 nor avelumab plus axitinib from JAVELIN Renal 101 demonstrated OS benefit compared to sunitinib,34,35 although the final survival analyses of JAVELIN Renal 101 are awaited. 35 The rest of this discussion will therefore focus on results from PD-1 combinations, noting that these data should be interpreted in the context that trials have been reported at different timepoints of mature follow-up and that differences exist between trials with regard to IMDC risk group populations studied.
At a median follow-up of 67.7 months, the dual ICI combination of nivolumab plus ipilimumab resulted in a significant 32% reduction in risk of death in intermediate/poor-risk patients and a 28% reduction in the risk of death in ITT patients compared with sunitinib,
33
although the rates of discontinuation of any treatment due to toxicity were higher for the combination (21.8%
Benefits were also seen for the PD-1 inhibitor pembrolizumab plus TKI combinations. At a median follow-up of 30.6 months, pembrolizumab plus axitinib reduced the risk of death by 32% (
In the absence of head-to-head trial comparisons, response outcomes may help refine selection between dual ICI or PD-1 inhibitor plus TKI combinations. The ORR reported for the dual ICI combination was 39% with an 18.2% rate of progressive disease, 48 while ORRs for PD-1 inhibitor plus TKI combinations were higher, ranging from 55.7% to 71.0%.28,29,31 The highest ORR was reported for pembrolizumab plus lenvatinib with rates of progressive disease ranging from 5.4% to 11.3%.28,29,31 A similar pattern was seen for complete responses, which ranged from 8% to 10%.28–31,49 DoRs can also be an important therapeutic consideration, potentially affording patients long-term benefit. DoRs for the PD-1 inhibitor plus TKI combinations ranged from 20 to 26 months,28,29,31 while the most durable responses were observed using the dual ICI combination, with the median DoR NR at a median follow-up of 67.7 months. 33 Furthermore, conditional survival data in intermediate/poor-risk patients treated with nivolumab/Ipilimumab showed a substantial increase in the percent probability of remaining progression-free for an additional 2 years beyond randomization (36%) compared with 3 years following randomization (90%), suggesting that responding patients have durable progression-free benefits. In patients with high tumor burden or aggressive course of disease where arresting tumor growth is clinically urgent and progression can be immediately catastrophic, an upfront approach using a PD-1 inhibitor plus a TKI may be preferred based on low rates of progressive disease seen with these regimens. All treatment decisions should consider both the evidence and patient preference and should be made in close collaborations with their physician.
What is the safety of ICI combination therapy in the first-line treatment of advanced RCC?
TKIs are commonly associated with hypertension, diarrhea, palmar-plantar erythrodysesthesia (PPE) and fatigue, and sunitinib generally requires administration daily for 4 weeks out of 6 weeks, which can increase toxicity.28–31 Any grade TRAEs rates for sunitinib ranged from 82.8% to 97.6% with grade ⩾3 TRAEs ranging from 50.9% to 63.9%. In studies demonstrating an OS gain, the addition of a PD-1 inhibitor to a TKI increased grade ⩾3 TRAEs by 4.5–12.8%,28,31 with the smallest increase seen when pembrolizumab was added to axitinib.
31
In contrast, the combination of nivolumab plus ipilimumab decreased grade ⩾3 AEs by 17.3% compared with sunitinib, with significantly longer time to confirmed deterioration for the ICI combination (FKSI-19,
Figure 2(a) depicts grade 1/2 and grade ⩾3 TRAEs of PD-1 inhibitor plus TKI combinations that were shown to prolong survival.28,29,43 Toxicity profiles were relatively consistent across combinations, with hypertension, diarrhea, and PPE being the most common grade ⩾3 TRAEs, despite steroid use in 29% and 21% of patients in the CheckMate 214 and CheckMate 9ER trials, respectively.48,56 When the mean toxicity rates for the PD-1 inhibitor plus TKI combinations were plotted against those of the dual ICI combinations (Figure 2(b)), higher rates of hypertension, PPE, diarrhea, dysphonia, hypothyroidism, stomatitis, and decreased appetite were observed while the ICI combinations were associated with higher rates of pruritis and rash.27–31

Select TRAE rates in phase III trials of ICI combinations. (a) TKI combination trials (ICI + TKI). (b) Average ICI + TKI and ICI + ICI TRAE rates.
Do some first-line patients benefit more from ICI combinations than others?
Results from first-line trials show that ICI combinations significantly improved OS in patients with advanced RCC, although some IMDC risk groups benefited more than others. Results from subgroup analyses must be interpreted with caution as outcomes may be influenced by imbalances in baseline characteristics and studies were not designed to compare outcomes in these subgroups. IMDC risk subgroup outcomes were available for five trials (CheckMate 214, JAVELIN Renal 101, KEYNOTE-426, CheckMate 9ER, and CLEAR), which reported outcomes for intermediate/poor-risk patients representing between 66% and 78% of the ITT populations. When assessing intermediate and poor-risk groups, OS favored ICI combinations for all combinations, with relatively tight confidence intervals that did not cross unity (Figure 3(a)).27-29,31,57 In intermediate-risk patients, OS favored ICI combinations but the benefit was less pronounced with CIs crossing unity in CheckMate 9ER. 28 When assessing the favorable-risk patients, this population appeared to representing between 22% and 33% of the included studies.27–29,31,57 Benefit in these patients was less clear with OS favoring ICI combinations in some studies and sunitinib in others, with CIs that were wide and crossed unity. Assessment of OS benefit in favorable-risk patient subgroups requires longer follow-up, although initial PFS benefits appear promising for nivolumab plus cabozantinib (HR = 0.58), 58 avelumab plus axitinib (HR = 0.63) 59 and pembrolizumab plus axitinib (HR = 0.76). 36 ICI combination outcomes vary based on IMDC-risk, with the greatest benefit observed for poor-risk and intermediate/poor-risk patients.

OS in select subgroups. (a) OS in IMDC risk subgroups. (b) OS in sarcomatoid subgroups.
Sarcomatoid differentiation, levels of tumor PD-L1 expression, and nephrectomy status have been assessed as factors to identify patients who may benefit from ICI combination therapy. Five trials evaluated OS in patients with tumors having sarcomatoid differentiation (CheckMate 214, IMmotion151, KEYNOTE-426, CheckMate9 ER and CLEAR), with approximately 7%–16% of patients in this subgroup across trials.32,56,60–64 Survival outcomes generally favored ICI combinations compared with sunitinib,32,56,60–64 with the greatest benefit associated with the dual ICI combination and nivolumab plus cabozantinib (Figure 3(b)).56,63,64 Five of the six ICI combination trials reported outcomes based on PD-L1 expression status, with no association detected between PD-L1 status and survival (Figure S1). Four trials reported outcomes based on nephrectomy status, with none showing a clear association between this variable and survival.27,28,31,57,62
What are the factors in selecting among first-line ICI combination therapies for advanced RCC?
Four ICI combinations have demonstrated an OS benefit compared to sunitinib in patients with first-line advanced RCC and an ECOG PS ⩽2,27,28,33,35–37 although five have shown either PFS or OS benefits and are currently approved by the United States Food and Drug administration and/or the European Medicines Agency (Table S2). Treatment selection should incorporate patient and disease characteristics, IMDC risk status, treatment history prior to the onset of advanced disease, and eligibility for immunotherapy. For patients with an intermediate/poor IMDC risk, nivolumab plus ipilimumab may be a good option due to the strong and durable OS benefit in patients suitable for combination ICI therapy. All three ICI plus TKI options, pembrolizumab plus axitinib, pembrolizumab plus Lenvatinib, and nivolumab plus cabozantinib are also life-prolonging options and offer higher ORRs with the lowest progressive disease rates, although they may be associated with chronic toxicities due to extended TKI use. For patients with a favorable IMDC risk, subgroup analyses suggest that further follow-up is required (Figure 3(a)) and nivolumab plus ipilimumab has not been approved for this subgroup in many jurisdictions.
What is the state of the future for combination strategies in RCC?
The role of ICI combinations is rapidly evolving, with multiple-phase III trials underway for both advanced RCC and for adjuvant treatment (Table 3). In advanced disease, established ICI plus TKI combinations are being assessed in clear-cell component tumors with or without sarcomatoid features (PDIGREE – NCT03793166) while new ICI combinations are also being evaluated such as the TKI combinations TQB2450 plus anlotinib (NCT04523272) and toripalimab plus axitinib (NCT04394975), in addition to the PEGylated interleukin-2 bempegaldesleukin plus nivolumab (NCT03729245). The future may shift again, with triplet strategies being evaluated first-line globally using established ICIs in COSMIC-313 (NCT03937219) and belzutifan, a selective small molecule inhibitor of hypoxia-inducible factor-2α, in MK-6482-012 (NCT04736706). In the adjuvant setting, dual ICI combinations including nivolumab plus ipilimumab (NCT03138512), durvalumab plus tremelimumab (NCT03288532), and pembrolizumab plus belzutifan (NCT05239728) are being assessed as in patients with intermediate/high risk of relapse. The role of ICI combinations is rapidly evolving and ongoing trials will inform optimal use across the disease trajectory.
Ongoing Phase III Clinical Trials of Immune Checkpoint Inhibitor Combination Therapy in Early Stage or First-Line Advanced Renal Cell Carcinoma.
Ongoing (trials that are actively recruiting for which efficacy outcomes are not yet available) phase III trials of ICI combination regimens for treatment of early or advanced RCC listed at CT.gov on 22 April 2021 are ordered by treatment setting and estimated primary completion date.
DFS, disease-free survival; ICI, immune checkpoint inhibitor; IMDC, International Metastatic RCC Database Consortium; ORR; objective response rate; OS, overall survival; PCD, primary completion date; PFS, progression-free survival; RCC, renal cell carcinoma.
Summary
Recent outcomes from first-line ICI combination trials have reported OS benefit compared to sunitinib in advanced RCC, all of which present efficacious treatment options in this setting depending on IMDC risk status. The dual ICI combination nivolumab plus ipilimumab demonstrated a robust and durable OS benefit with a relatively favorable safety profile compared to sunitinib in IMDC intermediate or poor-risk patients. Pembrolizumab plus axitinib or lenvatinib and nivolumab plus cabozantinib demonstrated an OS benefit in patients regardless of IMDC risk. Research into novel therapies and to elucidate the role of ICI combinations in earlier lines of treatment are ongoing and will help inform the optimal role of these combinations in this rapidly evolving treatment landscape.
Supplemental Material
sj-docx-1-tam-10.1177_17588359221108685 – Supplemental material for Evolving landscape of first-line combination therapy in advanced renal cancer: a systematic review
Supplemental material, sj-docx-1-tam-10.1177_17588359221108685 for Evolving landscape of first-line combination therapy in advanced renal cancer: a systematic review by Aly-Khan A. Lalani, Daniel Y. C. Heng, Naveen S. Basappa, Lori Wood, Nayyer Iqbal, Deanna McLeod, Denis Soulières and Christian Kollmannsberger in Therapeutic Advances in Medical Oncology
Supplemental Material
sj-docx-2-tam-10.1177_17588359221108685 – Supplemental material for Evolving landscape of first-line combination therapy in advanced renal cancer: a systematic review
Supplemental material, sj-docx-2-tam-10.1177_17588359221108685 for Evolving landscape of first-line combination therapy in advanced renal cancer: a systematic review by Aly-Khan A. Lalani, Daniel Y. C. Heng, Naveen S. Basappa, Lori Wood, Nayyer Iqbal, Deanna McLeod, Denis Soulières and Christian Kollmannsberger in Therapeutic Advances in Medical Oncology
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