Immunotherapy Benefit in a Patient With Non-Small Cell Lung Cancer and a Rare BRAF Mutation

Outcomes of non-small cell lung cancer patients with non-V600E BRAF mutations: a series of case reports and literature review

Non-small cell lung cancer (NSCLC) is the most prevalent form of lung cancer, accounting for approximately 85% of cases of lung cancer. The standard first-line therapy for patients without oncogenic driver metastatic NSCLC is anti PD-L1 immune checkpoint inhibition (ICI) with platinum-based chemotherapy. Approximately 4% of NSCLC patients harbor BRAF mutations; the V600E mutation is the most common. Non-V600 mutations is an heterogeneous population and account for approximately 50% of BRAF-mutated NSCLC. BRAF mutations are classified into 3 functional classes based on their kinase activity and their signaling mechanism. The European Medicines Agency and the United States Food and Drug Administration have approved dabrafenib, an anti-BRAF tyrosine kinase inhibitor (TKI), in combination with trametinib, an anti-MEK TKI, for the treatment of patients with BRAF V600E-mutated metastatic NSCLC. The use of targeted therapies in NSCLC with BRAF non-V600E mutations remains controversial. There is a lack of guidelines regarding therapeutic options in non-V600E BRAF-mutated NSCLC. Herein, we presented 3 cases of NSCLC with BRAF non-V600E mutations and reviewed the current state of therapies for this particular population of lung cancer.

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.

Squamous cell histological transformation in a lung adenocarcinoma patient (hyper) progressing upon immunotherapy

INTRODUCTION

In non-small cell lung cancer (NSCLC) histologic transformation upon immune checkpoint inhibitors (ICI) is rare.

CASE PRESENTATION

We described the case of a patient with early-stage lung adenocarcinoma who relapsed after surgery. At the time of relapse, he received chemo-radiotherapy, followed by consolidation immunotherapy. After 3 cycles the patient experienced disease hyperprogression for onset of a new lung mass, which resulted in squamous cell carcinoma. The preservation of an atypical mutation in the v-raf murine sarcoma viral oncogene homolog B1 (BRAF) gene in both the primary adenocarcinoma and the new squamous carcinoma suggests histological transformation, likely ICI-related.

DISCUSSION

We reviewed similar cases in literature, highlighting common patterns and substantial differences. For a deeper insight into inherent biological mechanisms, re-biopsy in case of atypical ICI response should be encouraged.

[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.