Abstract: We identified eight studies with 4732 eligible participants and an additional 13 ongoing studies. We categorized studies into comparisons, all against standard therapy accordingly as first-line (five comparisons) or second-line therapy (one comparison) for mRCC. Interferon (IFN)-α monotherapy probably increases one-year overall mortality compared to standard targeted therapies with temsirolimus or sunitinib (RR 1.30, 95% CI 1.13 to 1.51; 2 studies; 1166 participants; moderate-quality evidence), may lead to similar quality of life (QoL) (e.g. MD -5.58 points, 95% CI -7.25 to -3.91 for Functional Assessment of Cancer - General (FACT-G); 1 study; 730 participants; low-quality evidence) and may slightly increase the incidence of adverse events (AEs) grade 3 or greater (RR 1.17, 95% CI 1.03 to 1.32; 1 study; 408 participants; low-quality evidence). There is probably no difference between IFN-α plus temsirolimus and temsirolimus alone for one-year overall mortality (RR 1.13, 95% CI 0.95 to 1.34; 1 study; 419 participants; moderate-quality evidence), but the incidence of AEs of 3 or greater may be increased (RR 1.30, 95% CI 1.17 to 1.45; 1 study; 416 participants; low-quality evidence). There was no information on QoL. IFN-α alone may slightly increase one-year overall mortality compared to IFN-α plus bevacizumab (RR 1.17, 95% CI 1.00 to 1.36; 2 studies; 1381 participants; low-quality evidence). This effect is probably accompanied by a lower incidence of AEs of grade 3 or greater (RR 0.77, 95% CI 0.71 to 0.84; 2 studies; 1350 participants; moderate-quality evidence). QoL could not be evaluated due to insufficient data. Treatment with IFN-α plus bevacizumab or standard targeted therapy (sunitinib) may lead to similar one-year overall mortality (RR 0.37, 95% CI 0.13 to 1.08; 1 study; 83 participants; low-quality evidence) and AEs of grade 3 or greater (RR 1.18, 95% CI 0.85 to 1.62; 1 study; 82 participants; low-quality evidence). QoL could not be evaluated due to insufficient data. Treatment with vaccines (e.g. MVA-5T4 or IMA901) or standard therapy may lead to similar one-year overall mortality (RR 1.10, 95% CI 0.91 to 1.32; low-quality evidence) and AEs of grade 3 or greater (RR 1.16, 95% CI 0.97 to 1.39; 2 studies; 1065 participants; low-quality evidence). QoL could not be evaluated due to insufficient data. In previously treated patients, targeted immunotherapy (nivolumab) probably reduces one-year overall mortality compared to standard targeted therapy with everolimus (RR 0.70, 95% CI 0.56 to 0.87; 1 study; 821 participants; moderate-quality evidence), probably improves QoL (e.g. RR 1.51, 95% CI 1.28 to 1.78 for clinically relevant improvement of the FACT-Kidney Symptom Index Disease Related Symptoms (FKSI-DRS); 1 study, 704 participants; moderate-quality evidence) and probably reduces the incidence of AEs grade 3 or greater (RR 0.51, 95% CI 0.40 to 0.65; 1 study; 803 participants; moderate-quality evidence). Evidence of moderate quality demonstrates that IFN-α monotherapy increases mortality compared to standard targeted therapies alone, whereas there is no difference if IFN is combined with standard targeted therapies. Evidence of low quality demonstrates that QoL is worse with IFN alone and that severe AEs are increased with IFN alone or in combination. There is low-quality evidence that IFN-α alone increases mortality but moderate-quality evidence on decreased AEs compared to IFN-α plus bevacizumab. Low-quality evidence shows no difference for IFN-α plus bevacizumab compared to sunitinib with respect to mortality and severe AEs. Low-quality evidence demonstrates no difference of vaccine treatment compared to standard targeted therapies in mortality and AEs, whereas there is moderate-quality evidence that targeted immunotherapies reduce mortality and AEs and improve QoL.

Plain-language summary: A systematic search up to the end of October 2016 identified eight studies that looked at four different types of immunotherapy in 4732 people. Studies were only included if patients were randomized to a form of immunotherapy included in this review or a standard form of targeted therapy. One study was funded by a public institution whereas all the others were supported by drug companies. The study participants were generally representative of people with advanced kidney cancer. The majority of people had their kidney cancer removed before starting treatment. We compared studies of people who had previously received standard medicine (821 participants) to those of people who had not (3911 participants). All studies reported our main outcome of interest; the chance of longer survival including the survival for one year. We also focused on the frequency of severe treatment side effects, quality of life and the delay in disease worsening. Interferon-α was the most commonly used therapy option prior to the era of targeted therapies. Two studies with 1166 participants compared interferon-α alone (monotherapy) to targeted standard therapy. Interferon-α is probably inferior to tested targeted therapies called sunitinib and temsirolimus. Patients with interferon-α monotherapy probably have a shorter time to worsening of cancer. They may have similar quality of life and a slightly more severe treatment side effects. Adding temsirolimus to interferon-α probably does not improve survival compared to temsirolimus alone, but may result in more major side effects (one study). Two studies compared interferon-α to a combination of interferon-α and bevacizumab in 1381 previously untreated participants. There was a slightly increased death rate with probably fewer major side effects for people treated with interferon-α alone. Two studies evaluated vaccines. Vaccines may lead to similar death rates and side effects in people with advanced kidney cancer. For patients who had already undergone systemic treatment, one study with nivolumab, a novel checkpoint inhibitor, improved average survival by more than five months when compared to the targeted standard therapy, everolimus. The effects are probably accompanied by better quality of life and fewer major side effects. We had reduced confidence in the results of the studies we analyzed (moderate- or low-quality evidence) because patients and treating physicians were often not blinded to the treatment and involved relatively few patients.