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Expert Examines Emerging Biomarkers in NSCLC

Kristi Rosa
Published: Tuesday, Jan 22, 2019

Brandon Weckbaugh, MD

Brandon Weckbaugh, MD

The treatment landscape of non–small cell lung cancer (NSCLC) continues to expand with potential biomarkers that are under investigation, as well as novel agents that could potentially target them. What was once a major area of unmet need has experienced an explosion of new research, said Brandon Weckbaugh, MD.

“In NSCLC, when a patient is diagnosed with metastatic NSCLC, we will check for actionable mutations,” said Weckbaugh. “Currently, there are EGFR, ROS1, and ALK—to give a few examples. But there are a few emerging biomarkers for which there are newly approved, or likely soon-to-be approved, drugs that are able to target these mutations.”

Beyond EGFR, ROS1, and ALK, are RET, HER2, and NTRK, according to Weckbaugh, and some of these biomarkers already have targeted drugs approved for them. For example, with regards to RET, the FDA granted LOXO-292 a breakthrough therapy designation in September 2018 as a treatment for patients with advanced RET fusion–positive NSCLC based on data from the phase I LIBRETTO-001 trial, which showed an objective response rate of 77% (95% CI, 58%-90%) in this patient population.1

In terms of NTRK, in November 2018, the FDA approved larotrectinib (Vitrakvi) for adult and pediatric patients with solid tumors that have NTRK gene fusions without a known acquired resistance mutation. Furthermore, the FDA granted a breakthrough therapy designation to entrectinib in May 2017 for the treatment of adult and pediatric patients with NTRK-positive, locally advanced or metastatic solid tumors who have either progressed following prior therapies or who have no acceptable standard treatments.

Tumor mutational burden (TMB) is also being explored as a potential biomarker in NSCLC. One study published in 2017 examined the relationship between TMB and outcome in several cancers treated with various immunotherapies. For the study, a total of 151 patients treated with immunotherapy were assessed for response rate, progression-free survival (PFS), and overall survival (OS). Higher TMB was linked with better outcome parameters.2

The response rate for patients with high TMB (≥20 mutations/megabase [mb]) versus low-to-intermediate TMB was 58% (22/38) compared with 20% (23/113; P = .0001). Median PFS was 12.8 months in those with high TMB compared with 3.3 months in those with low-to-intermediate TMB (P ≤.0001), while the median OS was not reached versus 16.3 months (P = .0036).

Results were found to be similar when single agent PD-1/PD-L1 inhibitors were analyzed in 102 patients. Investigators observed a linear correlation between higher TMB and favorable outcome parameters. The median TMB for responders versus nonresponders treated with anti–PD-1/PD-L1 monotherapy was 18.0 compared with 5.0 mutations/mb (P < 0.0001).

In an interview during the 2018 OncLive® State of the Science SummitTM on Advanced Non–Small Cell Lung Cancer, Weckbaugh, an oncology fellow at the University of Missouri-Kansas City, shed light on emerging biomarkers in NSCLC.

OncLive: What drugs have recently been approved for some emerging biomarkers in NSCLC?

Weckbaugh: Previously, this was an area of unmet need with actionable mutations in NSCLC. But more recently, there have been a couple of new drugs approved, which are targeted for some of these mutations. To take NTRK as an example, there are 2 drugs that have [shown promise]—entrectinib and larotrectinib. These have shown very good efficacy and responsiveness for patients with NTRK-mutated NSCLC, which is important because NTRK is mutually exclusive with other oncogenic drivers. This is why I say this is an area of unmet need for targetable therapies.

Could you discuss tumor mutational burden (TMB) and how it’s being investigated as a potential biomarker?

Previously, when we were diagnosing metastatic NSCLC, one of the markers to check was PD-1/PD-L1 expression of the tumor. There have been times when that has been a little bit frustrating, as it is not a perfect predictor of how the patient is going to respond to therapy. By using TMB, the theory was that this would increase the immunogenicity of the patient's tumors.

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Community Practice Connections™: 14th Annual International Symposium on Melanoma and Other Cutaneous Malignancies®Apr 30, 20192.0
Oncology Consultations®: The Advancing Role of CAR T-Cell Therapies in Hematologic MalignanciesApr 30, 20191.5
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