OA12.05 Vemurafenib in Patients Harboring V600 and Non V600 BRAF Mutations: Final Results of the NSCLC Cohort from the AcSé Trial

The Evolution of BRAF Activation in Non-Small-Cell Lung Cancer

Non-small-cell lung cancer (NSCLC) is the most common subtype of lung cancer, of which approximate 4% had BRAF activation, with an option for targeted therapy. BRAF activation comprises of V600 and non-V600 mutations, fusion, rearrangement, in-frame deletions, insertions, and co-mutations. In addition, BRAF primary activation and secondary activation presents with different biological phenotypes, medical senses and subsequent treatments. BRAF primary activation plays a critical role in proliferation and metastasis as a driver gene of NSCLC, while secondary activation mediates acquired resistance to other targeted therapy, especially for epidermal growth factor tyrosine kinase inhibitor (EGFR-TKI). Treatment options for different activation of BRAF are diverse. Targeted therapy, especially two-drug combination therapy, is an important option. Besides, immune checkpoint inhibitors (ICIs) would be another option since BRAF activation would be a positive biomarker of tumor response of ICIs therapy. To date, no high level evidences support targeted therapy or immunotherapy as prioritized recommendation. After targeted therapy, the evolution of BRAF includes the activation of the upstream, downstream and bypass pathways of BRAF. In this review, therapeutic modalities and post-therapeutic evolutionary pathways of BRAF are discussed, and future research directions are also provided.

[Strategic Exploration of Targeted Therapy for BRAF Non-V600E Mutant Lung Cancer]

BACKGROUND

Dabrafenib+Trametinib/Dabrafenib targeted therapy has been approved for V-RAF murine sarcoma viral oncogene homolog B1 with amino acid substitution for valine at position 600 (BRAF V600E) in lung cancer patients, however, the targeted therapy strategy for lung cancer patients with BRAF non-V600E mutations has not been determined yet. This study intends to explore the efficacy of targeted therapy for BRAF non-V600E mutant lung cancer, and provide a reference for clinical treatment.

METHODS

Computer search of PubMed, Cochrane Library, Embase, Web of Science, Clinicaltrials.gov, CBM, CNKI, Wanfang database. Collect the relevant literature relevant on the targeted therapy of BRAF non-V600E mutant lung cancer, and conduct a descriptive analysis of the included literature.

RESULTS

There were 10 articles that met the inclusion criteria, including 3 cohort studies and 7 case reports. 18 patients with BRAF non-V600E mutant lung cancer were ineffective to vermurafenib; 1 patient obtained partial response (PR) after applying vermurafenib, 5 patients did not respond to BRAF inhibitors; 9 patients showed a potential clinical benefit rate of 34% after monotherapy with trametinib; 7 patients have different degrees of benefit from dabrafenib and trametinib on progression-free survival (PFS); 1 patient is effective to sorafenib.

CONCLUSIONS

At present, there is no standard treatment specification for BRAF non-V600E mutation targeted therapy. The challenge lies in the heterogeneous mutation of BRAF gene. Different mutation types respond differently to targeted therapy. In addtion, real-world research evidence is scarce, so it is necessary to carry out further large-sample high-quality research to provide reference for clinical practice.

Circulating Tumor DNA Genomics Reveal Potential Mechanisms of Resistance to BRAF-Targeted Therapies in Patients with BRAF-Mutant Metastatic Non-Small Cell Lung Cancer

PURPOSE

The limited knowledge on the molecular profile of patients with BRAF-mutant non-small cell lung cancer (NSCLC) who progress under BRAF-targeted therapies (BRAF-TT) has hampered the development of subsequent therapeutic strategies for these patients. Here, we evaluated the clinical utility of circulating tumor DNA (ctDNA)-targeted sequencing to identify canonical BRAF mutations and genomic alterations potentially related to resistance to BRAF-TT, in a large cohort of patients with BRAF-mutant NSCLC.

EXPERIMENTAL DESIGN

This was a prospective study of 78 patients with advanced BRAF-mutant NSCLC, enrolled in 27 centers across France. Blood samples (n = 208) were collected from BRAF-TT-naïve patients (n = 47), patients nonprogressive under treatment (n = 115), or patients at disease progression (PD) to BRAF-TT (24/46 on BRAF monotherapy and 22/46 on BRAF/MEK combination therapy). ctDNA sequencing was performed using InVisionFirst-Lung. In silico structural modeling was used to predict the potential functional effect of the alterations found in ctDNA.

RESULTS

BRAF^V600E ctDNA was detected in 74% of BRAF-TT-naïve patients, where alterations in genes related with the MAPK and PI3K pathways, signal transducers, and protein kinases were identified in 29% of the samples. ctDNA positivity at the first radiographic evaluation under treatment, as well as BRAF-mutant ctDNA positivity at PD were associated with poor survival. Potential drivers of resistance to either BRAF-TT monotherapy or BRAF/MEK combination were identified in 46% of patients and these included activating mutations in effectors of the MAPK and PI3K pathways, as well as alterations in U2AF1, IDH1, and CTNNB1.

CONCLUSIONS

ctDNA sequencing is clinically relevant for the detection of BRAF-activating mutations and the identification of alterations potentially related to resistance to BRAF-TT in BRAF-mutant NSCLC.

A BRAF new world

BRAF is a rare targetable mutation in non-small-cell lung cancer (NSCLC). Emerging evidence underlines that, rather than a single point mutation, BRAF genes present with a wide array of mutations, essentially in lung adenocarcinoma. Different BRAF mutations have divergent clinical and therapeutic implications, with a particular distinction between V600E and non-V600E mutations. The latter are at least as frequent in NSCLC as V600E, but lack any proven targeted therapy. In this paper, we briefly review the current literature and provide an update of scientific knowledge about different types of BRAF mutations in NSCLC.

Advanced-Stage Non-Small Cell Lung Cancer: Advances in Thoracic Oncology 2018

In 2018 research in the field of advanced NSCLCs led to an expanded reach and impact of immune checkpoint inhibitors (ICIs) as part of a frontline treatment strategy, regardless of histologic subtype, with ICI use extended to include stage III disease, shifting the prognosis of all these patients. This new standard first-line approach opens a gap in standard second-line treatment, and older combinations may again become standard of care after progression during treatment with an ICI. The characterization of predictive biomarkers, patient selection, the definition of strategies with ICI combinations upon progression during treatment with ICIs, as well as prospective evaluation of the efficacy of ICIs in subpopulations (such as patients with poor performance status or brain metastases) represent upcoming challenges in advanced thoracic malignancies. In oncogene-addicted NSCLC three major steps were taken during 2018: next-generation tyrosine kinase inhibitors have overtaken more established agents as the new standard of care in EGFR and ALK receptor tyrosine kinase gene (ALK)-positive tumors. Mechanisms of acquired resistance have been reported among patients treated with next-generation EGFR tyrosine kinase inhibitors, reflecting the diversity of the landscape. One major step forward was the approval of personalized treatment in very uncommon genomic alterations, mainly fusions. This raises a new question about the challenge of implementation of next-generation sequencing in daily clinical practice to detect new and uncommon genomic alterations and to capture the heterogeneity of the mechanisms of acquired resistance during treatment, as well as the need to extend research into new therapeutic strategies to overcome them.