High tumor mutation burden fails to predict immune checkpoint blockade response across all cancer types.

BACKGROUND: High tumor mutation burden (TMB-H) has been proposed as a predictive biomarker for response to immune checkpoint blockade (ICB), largely due to the potential for tumor mutations to generate immunogenic neoantigens. Despite recent pan-cancer approval of ICB treatment for any TMB-H tumor, as assessed by the targeted FoundationOne CDx assay in nine tumor types, the utility of this biomarker has not been fully demonstrated across all cancers. PATIENTS AND METHODS: Data from over 10 000 patient tumors included in The Cancer Genome Atlas were used to compare approaches to determine TMB and identify the correlation between predicted neoantigen load and CD8 T cells. Association of TMB with ICB treatment outcomes was analyzed by both objective response rates (ORRs, N = 1551) and overall survival (OS, N = 1936). RESULTS: In cancer types where CD8 T-cell levels positively correlated with neoantigen load, such as melanoma, lung, and bladder cancers, TMB-H tumors exhibited a 39.8% ORR to ICB [95% confidence interval (CI) 34.9-44.8], which was significantly higher than that observed in low TMB (TMB-L) tumors [odds ratio (OR) = 4.1, 95% CI 2.9-5.8, P < 2 × 10-16]. In cancer types that showed no relationship between CD8 T-cell levels and neoantigen load, such as breast cancer, prostate cancer, and glioma, TMB-H tumors failed to achieve a 20% ORR (ORR = 15.3%, 95% CI 9.2-23.4, P = 0.95), and exhibited a significantly lower ORR relative to TMB-L tumors (OR = 0.46, 95% CI 0.24-0.88, P = 0.02). Bulk ORRs were not significantly different between the two categories of tumors (P = 0.10) for patient cohorts assessed. Equivalent results were obtained by analyzing OS and by treating TMB as a continuous variable. CONCLUSIONS: Our analysis failed to support application of TMB-H as a biomarker for treatment with ICB in all solid cancer types. Further tumor type-specific studies are warranted.

A phase I dose-escalation and dose-expansion study of brontictuzumab in subjects with selected solid tumors.

Background: Brontictuzumab is a monoclonal antibody that targets Notch1 and inhibits pathway activation. The purpose of this first-in-human study was to determine the maximum tolerated dose (MTD), safety, pharmacokinetics, immunogenicity and preliminary efficacy of brontictuzumab in patients with solid tumors. Patients and methods: Subjects with selected refractory solid tumors were eligible. Brontictuzumab was administered intravenously at various dose levels and schedule during dose escalation, and at 1.5 mg/kg every 3 weeks (Q3W) during expansion. Evidence of Notch1 pathway activation as determined by an immunohistochemistry assay was required for entry in the expansion cohort. Adverse events were graded according to the NCI-CTCAE v 4.03. Efficacy was assessed by RECIST 1.1. Results: Forty-eight subjects enrolled (33 in dose escalation and 15 in the expansion phase). The MTD was 1.5 mg/kg Q3W. Dose-limiting toxicities were grade 3 diarrhea in two subjects and grade 3 fatigue in one subject. The most common drug-related adverse events of any grade were diarrhea (71%), fatigue (44%), nausea (40%), vomiting (21%), and AST increase (21%). Brontictuzumab exhibited nonlinear pharmacokinetics with dose-dependent terminal half-life ranging 1-4 days. Clinical benefit was seen in 6 of 36 (17%) assessable subjects: 2 had unconfirmed partial response (PR) and 4 subjects had prolonged (≥ 6 months) disease stabilization (SD). Both PRs and three prolonged SD occurred in adenoid cystic carcinoma (ACC) subjects with evidence of Notch1 pathway activation. Pharmacodynamic effects of brontictuzumab were seen in patients' blood and tumor. Conclusion: Brontictuzumab was well tolerated at the MTD. The main toxicity was diarrhea, an on-target effect of Notch1 inhibition. An efficacy signal was noted in subjects with ACC and Notch1 pathway activation. ClinicalTrials.gov identifier: NCT01778439.

Association between KRAS mutation and lung metastasis in advanced colorectal cancer.

BACKGROUND: KRAS mutations have been associated with lung metastases at diagnosis of metastatic colorectal cancer (mCRC), but the impact of this mutation on subsequent development of lung metastasis is unknown. We investigated KRAS mutation as a predictor of lung metastasis development. METHODS: We retrospectively evaluated data from patients with mCRC whose tumour was tested for KRAS mutation from 2008 to 2010. The relationships of KRAS mutational status with time-to-lung metastasis (TTLM) and overall survival (OS) were analysed. RESULTS: Of the 494 patients identified, 202 (41%) had tumours with KRAS mutation. KRAS mutations were associated with a shorter TTLM (median 15.2 vs 22.4 months; hazard ratio=1.40; P=0.002) and a two-fold greater odds of developing lung metastases during the disease course in patients with liver-limited mCRC at diagnosis (72 vs 56%, P=0.007). Overall survival did not differ by KRAS status. CONCLUSIONS: Lung metastasis was more likely to develop during the disease course in patients whose tumour had a KRAS mutation than in those whose tumour did not have a KRAS mutation. This finding may have an impact on decision making for surgical resection of metastatic disease.