Is immunotherapy more effective and less toxic than chemotherapy for people diagnosed with non-small cell lung cancer (a subtype of lung cancer) who have not previously been treated and who are not suitable for curative treatment?
Lung cancer is the leading cause of cancer deaths and non-small cell lung cancer represent more than 85% of all lung cancer cases. Curative surgery and radiotherapy are not treatment options when the disease is at an advanced stage and until recently these people were offered chemotherapy. Since 2016, immunotherapies (antibodies able to stimulate the immune system against cancer cells) have been shown to improve survival for these patients.
Side effects of immunotherapies are mainly inflammation of the tissues caused by the activation of the immune system against different organs, while chemotherapy usually causes a reduction in the white blood cells and red blood cells, hair loss, nausea and vomiting.
In this Cochrane Review, we tried to find out how effective and safe immunotherapies (given alone or as combinations) are compared to standard chemotherapy for people with non-small cell lung cancer who are not suitable for possibly curative treatment.
We searched the main databases and records of conference meetings up to 21st October 2020. We included seven studies (5893 participants) comparing immunotherapies (antibodies that interact with specific proteins called immune checkpoints) with chemotherapy for people with non-small cell lung cancer not previously treated.
We reported the results by PD-L1 levels (a protein produced by the tumour or immune cells and bound by immune checkpoint inhibitors)
In people with more than 50% of tumour/immune cells expressing PD-L1 protein, single immunotherapy might improve survival with fewer side effects. In addition, treatment with combined immunotherapies may improve survival in both people with high expression of PD-L1 protein.The rate of toxic effects may be the same for people treated with combined immunotherapies or chemotherapy.
Certainty of evidence
Overall, the certainty of the evidence ranged from moderate to low.
For people with advanced non-small cell lung cancer with a high expression of PD-L1 protein, immunotherapies alone or combinations of immunotherapies prolonged life compared to chemotherapy. The frequency of side effects may be lower with the use of immunotherapies alone compared to chemotherapy. The frequency of side effects may not differ between combinations of immunotherapies and chemotherapy.
The evidence in this review suggests that single-agent ICI in people with NSCLC and PD-L1 ≥50% probably leads to a higher overall survival rate and may lead to a higher progression-free survival and overall response rate when compared to platinum-based chemotherapy and may also lead to a lower rate of adverse events and higher HRQoL. Combined ICI in people with NSCLC and PD-L1 ≥50% also probably leads to a higher overall survival rate when compared to platinum-based chemotherapy, but its effect on progression-free survival, overall response rate and HRQoL is unknown due to a lack of data. The rate of adverse events may not differ between groups.
Immune checkpoint inhibitors (ICIs) targeting the PD-1/PD-L1 axis have changed the first-line treatment of people with advanced non-small cell lung cancer (NSCLC). Single-agent pembrolizumab (a PD-1 inhibitor) is currently the standard of care as monotherapy in patients with PD-L1 expression ≥ 50%, either alone or in combination with chemotherapy when PD-L1 expression is less than 50%. Atezolizumab (PD-L1 inhibitor) has also been approved in combination with chemotherapy and bevacizumab (an anti-angiogenic antibody) in first-line NSCLC regardless of PD-L1 expression. The combination of first-line PD-1/PD-L1 inhibitors with anti-CTLA-4 antibodies has also been shown to improve survival compared to platinum-based chemotherapy in advanced NSCLC, particularly in people with high tumour mutational burden (TMB). The association of ipilimumab (an anti CTLA4) and nivolumab (PD-1 inhibitor) has been approved by the US Food and Drug Administration (FDA) in all patients with PD-L1 expression ≥1%. Although these antibodies are currently used in clinical practice, some questions remain unanswered, such as the best-treatment strategy, the role of different biomarkers for treatment selection and the effectiveness of immunotherapy according to specific clinical characteristics.
Primary objective: to determine the effectiveness and safety of first-line immune checkpoint inhibitors (ICIs), as monotherapy or in combination, compared to platinum-based chemotherapy, with or without bevacizumab for people with advanced NSCLC, according to the level of PD-L1 expression. Secondary objective: to maintain the currency of evidence using a living systematic review approach.
We performed an electronic search of the main databases (Cochrane Lung Cancer Group Trial Register, Cochrane Central Register of Controlled Trials, MEDLINE, Embase) from inception until 21 October 2020 and conferences meetings from 2015 onwards.
We included randomised controlled trials (RCTs) reporting on the efficacy or safety of first-line ICI treatment for adults with advanced NSCLC who had not previously received any anticancer treatment. We included trials comparing single- or double-ICI treatment to standard first-line therapy (platinum-based chemotherapy +/- bevacizumab). All data come from ‘international multicentre studies involving adults, age 18 or over, with histologically-confirmed stage IV NSCLC who had not received any previous systemic anti-cancer treatment for advanced disease.
Three review authors independently assessed the search results and a fourth review author resolved any disagreements. Primary outcomes were overall survival (OS) and progression-free survival (PFS); secondary outcomes were overall objective response rate (ORR) by RECIST v 1.1, grade 3 to 5 treatment-related adverse events (AEs) (CTCAE v 5.0) and health-related quality of life (HRQoL). We performed meta‐analyses where appropriate using the random-effects model for hazard ratios (HRs) or risk ratios (RRs), with 95% confidence intervals (95% CIs), and used the I² statistic to investigate heterogeneity.
We identified 15 trials for inclusion, seven completed and eight ongoing trials. We obtained data for 5893 participants from seven trials comparing first-line single- (six trials) or double- (two trials) agent ICI with platinum-based chemotherapy, one trial comparing both first-line single- and double-agent ICsI with platinum-based chemotherapy. All trials were at low risk of selection and detection bias, some were classified at high risk of performance, attrition or other source of bias. The overall certainty of evidence according to GRADE ranged from moderate-to-low because of risk of bias, inconsistency, or imprecision. The majority of the included trials reported their outcomes by PD-L1 expressions, with PD-L1 ≥ 50 being considered the most clinically useful cut-off level for decision makers. Also, iIn order to avoid overlaps between various PDL-1 expressions we prioritised the review outcomes according to PD-L1 ≥ 50.
In the PD-L1 expression ≥ 50% group single-agent ICI probably improved OS compared to platinum-based chemotherapy (hazard ratio (HR) 0.68, 95% confidence interval (CI) 0.60 to 0.76, 6 RCTs, 2111 participants, moderate-certainty evidence). In this group, single-agent ICI also may improve PFS (HR: 0.68, 95% CI 0.52 to 0.88, 5 RCTs, 1886 participants, low-certainty evidence) and ORR (risk ratio (RR):1.40, 95% CI 1.12 to 1.75, 4 RCTs, 1672 participants, low-certainty evidence). HRQoL data were available for only one study including only people with PD-L1 expression ≥ 50%, which suggested that single-agent ICI may improve HRQoL at 15 weeks compared to platinum-based chemotherapy (RR: 1.51, 95% CI 1.08 to 2.10, 1 RCT, 297 participants, low-certainty evidence).
In the included studies, treatment-related AEs were not reported according to PD-L1 expression levels. Grade 3-4 AEs may be less frequent with single-agent ICI compared to platinum-based chemotherapy (RR: 0.41, 95% CI 0.33 to 0.50, I² = 62%, 5 RCTs, 3346 participants, low-certainty evidence).
More information about efficacy of single-agent ICI compared to platinum-based chemotherapy according to the level of PD-L1 expression and to TMB status or specific clinical characteristics is available in the full text.
Double-ICI treatment probably prolonged OS compared to platinum-based chemotherapy in people with PD-L1 expression ≥50% (HR: 0.72, 95% CI 0.59 to 0.89 2 RCTs, 612 participants, moderate-certainty evidence).
Trials did not report data on HRQoL, PFS and ORR according to PD-L1 groups.
Treatment related AEs were not reported according to PD-L1 expression levels. The frequency of grade 3-4 AEs may not differ between double-ICI treatment and platinum-based chemotherapy (RR: 0.78, 95% CI 0.55 to 1.09, I² = 81%, 2 RCTs, 1869 participants, low-certainty evidence).
More information about efficacy of double-agent ICI according to the level of PD-L1 expression and to TMB status is available in the full text.