No abstract

Therapeutic antibodies that block the programmed death-ligand 1 (PD-L1)/programmed death-1 (PD-1) pathway can induce robust and durable responses in patients with various cancers, including metastatic urothelial cancer (mUC)1–5. However, these responses only occur in a subset of patients. Elucidating the determinants of response and resistance is key to improving outcomes and developing new treatment strategies. Here, we examined tumours from a large cohort of mUC patients treated with an anti–PD-L1 agent (atezolizumab) and identified major determinants of clinical outcome. Response was associated with CD8+ T-effector cell phenotype and, to an even greater extent, high neoantigen or tumour mutation burden (TMB). Lack of response was associated with a signature of transforming growth factor β (TGF-β) signalling in fibroblasts, particularly in patients with CD8+ T cells that were excluded from the tumour parenchyma and instead found in the fibroblast- and collagen-rich peritumoural stroma—a common phenotype among patients with mUC. Using a mouse model that recapitulates this immune excluded phenotype, we found that therapeutic administration of a TGF-β blocking antibody together with anti–PD-L1 reduced TGF-β signalling in stromal cells, facilitated T cell penetration into the centre of the tumour, and provoked vigorous anti-tumour immunity and tumour regression. Integration of these three independent biological features provides the best basis for understanding outcome in this setting and suggests that TGF-β shapes the tumour microenvironment to restrain anti-tumour immunity by restricting T cell infiltration.

Summary Background Patients with metastatic urothelial carcinoma have limited treatment options after failure of platinum-based chemotherapy. This multicenter, single-arm phase 2 trial evaluated atezolizumab, an engineered humanized IgG1 monoclonal antibody that binds selectively to programmed death–ligand 1 (PD-L1), in this population. Methods Three hundred and ten patients received atezolizumab (1200 mg, every 3 weeks). PD-L1 expression on tumor-infiltrating immune cells (IC) was prospectively assessed by immunohistochemistry. The co-primary endpoints were the objective response rate by RECIST v1.1 and immune modified RECIST. A hierarchical testing procedure was used to test whether the objective response rate was significantly higher than the historical control of 10% at alpha level of 0·05. Exploratory analyses included assessing the association between The Cancer Genome Atlas (TCGA) molecular subtypes, CD8+ T cell infiltration, mutation load, and clinical outcomes. Findings By independent review, objective response rates were 26% (95% CI 18 to 36) in the IC2/3 group, 18% (95% CI 13 to 24) in the IC1/2/3 group and 15% (95% CI 11 to 19) in all patients. With a median follow-up of 11·7 months, ongoing responses were observed in 84% of responders. The median duration of response was not reached (range 2·0*, 13·7* months, *censored). The median overall survival was 11·4 months (95% CI 9·0 to not estimable) in the IC2/3 group, 8·8 months (95% CI 7·1 to 10·6) in the IC1/2/3, and 7·9 months (95% CI 6·6 to 9·3) in all patients. Grade 3–4 related treatment-related adverse events occurred in 16% and grade 3–4 immune-mediated adverse events occurred in 5% of treated patients. Exploratory analyses showed TCGA subtypes and mutation load to be independently predictive for response to atezolizumab. Interpretation Atezolizumab demonstrated durable activity and good tolerability in this population. PD-L1 expression on immune cells was associated with response. This is the first report to show the association of TCGA subtypes with response to immune checkpoint inhibition and demonstrate the importance of mutation load as a biomarker of response to this class of agents in advanced urothelial carcinoma. Funding F. Hoffmann-La Roche Ltd.

There have been no major advances for the treatment of metastatic urothelial bladder cancer (UBC) in the last 30 years. Chemotherapy is still the standard of care. Patient outcomes, especially for those in whom chemotherapy is not effective or is poorly tolerated, remain poor. One hallmark of UBC is the presence of high rates of somatic mutations. These alterations may enhance the ability of the host immune system to recognize tumour cells as foreign owing to an increased number of antigens. However, these cancers may also elude immune surveillance and eradication through the expression of programmed death-ligand 1 (PD-L1; also called CD274 or B7-H1) in the tumour microenvironment. Therefore, we examined the anti-PD-L1 antibody MPDL3280A, a systemic cancer immunotherapy, for the treatment of metastatic UBC. MPDL3280A is a high-affinity engineered human anti-PD-L1 monoclonal immunoglobulin-G1 antibody that inhibits the interaction of PD-L1 with PD-1 (PDCD1) and B7.1 (CD80). Because PD-L1 is expressed on activated T cells, MPDL3280A was engineered with a modification in the Fc domain that eliminates antibody-dependent cellular cytotoxicity at clinically relevant doses to prevent the depletion of T cells expressing PD-L1. Here we show that MPDL3280A has noteworthy activity in metastatic UBC. Responses were often rapid, with many occurring at the time of the first response assessment (6 weeks) and nearly all were ongoing at the data cutoff. This phase I expansion study, with an adaptive design that allowed for biomarker-positive enriched cohorts, demonstrated that tumours expressing PD-L1-positive tumour-infiltrating immune cells had particularly high response rates. Moreover, owing to the favourable toxicity profile, including a lack of renal toxicity, patients with UBC, who are often older and have a higher incidence of renal impairment, may be better able to tolerate MPDL3280A versus chemotherapy. These results suggest that MPDL3280A may have an important role in treating UBC-the drug received breakthrough designation status by the US Food and Drug Administration (FDA) in June 2014.

Summary Background First-line chemotherapy for patients with cisplatin-ineligible locally-advanced or metastatic urothelial carcinoma (mUC) is associated with short response duration, poor survival, and high toxicity. This multicenter, 2-cohort phase 2 study evaluated atezolizumab (anti–programmed death-ligand 1 [PD-L1]) as treatment for mUC in this setting, as well as in later lines. Methods In a cohort of previously untreated patients who were cisplatin ineligible, atezolizumab was given 1200 mg every 3 weeks until progression. The primary endpoint was independently confirmed objective response rate per Response Evaluation Criteria In Solid Tumors v1.1 (central review), evaluated in pre-specified subgroups based on PD-L1 expression and in all patients. Secondary endpoints included response duration, progression-free survival, overall survival, and safety. Exploratory analyses included biomarker correlates of response and survival. This study is registered with ClinicalTrials.gov, number NCT02108652. Findings Of 119 patients who received atezolizumab in the first-line setting, 83 (70%) had baseline renal impairment, and 24 (20%) had Eastern Cooperative Oncology Group performance status 2. At 17·2 months’ median follow-up, the objective response rate was 23% (95% CI 16–31), the complete response rate was 9%, and 19 of 27 responses were ongoing. Median response duration was not reached. Responses occurred across all PD-L1 and poor prognostic factor subgroups. Median progression-free survival was 2·7 months. Median overall survival was 15·9 months. Tumour mutation load was associated with response. Treatment-related adverse events ≥10% were fatigue, diarrhoea, and pruritus. One treatment-related death (sepsis) occurred. Nine patients (8%) had an adverse event leading to treatment discontinuation. Immune-mediated events occurred in 14 (12%) patients. Interpretation Atezolizumab demonstrated encouraging durable response rates, survival, and tolerability, supporting its therapeutic use in untreated mUC. Funding F. Hoffmann-La Roche Ltd./Genentech, Inc., a member of the Roche Group.