EGFR-mutant NSCLC: Choice of First-Line Treatment May Get More Complicated


Medical guidelines for treatment of newly diagnosed non-small cell lung cancer (NSCLC) mandate upfront testing of tumor tissue for mutations in the EGFR gene (as well as ALK and ROS gene translocation). EGFR mutations are found in 10 to 15% of white patients, but in patients of East Asian origin such mutations are in encountered in approximately 48%. However, with new data and drugs entering the playing field, newly diagnosed patients’ treatment decisions could become more complex.

There is a good reason to test for EGFR mutations: the accumulated data show that, compared to first-line chemotherapy, treatment with drugs that inhibit the activity of EGFR in patients with activating EGFR mutations improves patients’ median progression-free survival (PFS) time from 4.6 to 6.9 months to 9.6 to 13.1 months, and has a higher objective response rate (ORR). Moreover, EGFR inhibitors are associated with a significantly lower incidence of adverse effects and better control of disease symptoms.

About 90% of EGFR mutations in EGFR are deletions in a portion of the gene known as exon 19 or a mutation in exon 21 (these mutations are known as del19 and L858R, respectively). The remaining mutations include alterations in exons 18 and 20, and these are associated with poor response to EGFR inhibitors.

The presence of the EGFR mutations del19 or L858R usually prompts doctors to prescribe one of the three EGFR inhibitors approved by the U.S. Food and Drug Administration (FDA) as a first-line treatment: erlotinib (Tarceva), gefitinib (Iressa), or afatinib (Gilotrif). Erlotinib and gefitinib are first-generation EGFR inhibitors, and afatinib is a second-generation drug. The first-generation inhibitors bind EGFR reversibly (they can attach and detach), whereas second generation inhibitors like afatinib bind to EGFR in an irreversible manner. All three inhibit not only the mutated EGFR protein, but also the normal EGFR that performs essential functions in some normal tissues. Afatinib also inhibits other members of the EGFR family of proteins (HER2 and HER4).

It is worth noting that none of these three drugs improve overall survival, with one exception, which I discuss later. The major side effects of EGFR inhibitors are skin rash and diarrhea, and the latter can be more severe with afatinib. In general, side effects are usually manageable and often transient, and by now, doctors have acquired much experience on how to alleviate them. Also, dose reductions to reduce side effects are possible with erlotinib and afatinib (but not with gefitinib). Gefitinib in general has lower risk of toxicities.

The choice between the three available inhibitors may depend on several factors: the oncologist’s preferences, the patient’s general condition, and importantly, the precise EGFR mutations identified in the patient’s tumor(s).

The del19 mutation is known to have the highest response rate to EGFR inhibitors amongst all EGFR mutations. A direct comparison in a large clinical trial showed an ORR of 72.5% with afatinib and 56% with gefitinib. There was no difference in PFS, but there was a trend in prolongation of overall survival with afatinib (27 versus 24 months).

Therefore, patients with del19 who are in a good overall condition should be given afatinib. The prevailing opinion is that gefitinib should be given to frail or older patients, or patients with other health concerns.

EGFR mutations other than L858R or del19, such as exon 20 insertions or exon 18 mutations, respond poorly to erlotinib and gefitinib. Patients whose tumors have these mutations do not have good treatment options, but are usually treated with afatinib, which has been shown to have better activity then first-generation inhibitors. There are now drugs in clinical trials specifically for patients with exon 20 insertions: a combination of poziotinib and AP32788, and osimertinib.

Obviously, the choice between the three FDA-approved first-line drugs requires careful consideration. However, it is apparently about to become a lot more difficult, with new contenders for first-line treatment in EGFR mutant NSCLC coming onto the scene. A combination of erlotinib with bevacizumab, a drug that limits blood supply to tumors, has already shown a superior PFS of 16 months versus 10 months with erlotinib alone. Another, and likely a stronger candidate, is osimertinib (Tagrisso), a third-generation inhibitor that does not bind to normal EGFR. Osimertinib is already FDA-approved for treatment of NSCLC with an EGFR mutation known as T790M.

T790M is very rarely found in untreated lung cancer, but arises during treatment with FDA-approved EGFR inhibitors in about 40 to 60% of patients, making them resistant to further treatment with first/second generation EGFR inhibitors. Osimertinib was developed to treat patients with T790M and has a reported ORR of 61%, which is very impressive. This is much higher than what is seen with chemotherapy in patients with resistance to first-line EGFR inhibitors: in a direct comparison in the AURA3 trial, a response rate of 71% was seen with osimertinib versus only 31% with chemotherapy. Moreover, osimertinib has activity (albeit much lower) even in the absence of a T790M mutation after resistance to erlotinib or gefitinb develops.

This latter feature led to testing of osimertinib as a first-line treatment in EGFR-mutant NSCLC. The trial included 60 patients who received two different doses of the drug, and the average ORR was 77%, with a median PFS of 20.5 months. These PFS data are much better than what is seen with any of the three FDA-approved first-line EGFR inhibitors (10 to 12 months).

There is a much larger trial ongoing, named FLAURA, which directly compares osimertinib with erlotinib or gefitinib in the frontline setting for patients with advanced EGFRmutant NSCLC. There is little doubt that the results, when published, would favor osimertinib, and this has been already announced in a press release issued by the trial sponsor.

It is possible that the FDA will approve osimertinib as the first-line treatment option for EGFR-positive NSCLC, which will make the choice of first-line drug difficult. What is better: sequence the available drugs, i.e., start with erlotinib followed by osimertinib when resistance develops (if T790M is identified), or give osimertinib outright?

Doing a simple calculation, erlotinib first may provide PFS of 9-13 months, followed by osimertinib (if T790M is present), adding another 10 months. Osimertinib given as first line can provide 20 months PFS. However, resistance to approved first-line EGFR inhibitors involves T790M in 40 to 60 % of patients, so perhaps it is more useful to use osimertinib right away? Not an easy question to answer. It would be wonderful if data could be somehow collected for the many patients who were treated with erlotinib, developed T790M mutation, and switched to osimertinib, rather than to conduct randomized trials. But this is unlikely to happen.


Tagrisso Shows Benefit in NSCLC Patients With CNS Metastases

Excerpt:

“AstraZeneca has presented new data showing that Tagrisso also extends progression-free survival for non-small cell lung cancer (NSCLC) patients who have central nervous system (CNS) metastases.

“According to findings from the AURA3 trial, patients with locally advanced or metastatic epidermal growth factor receptor (EGFR) T790M mutation-positive NSCLC given the drug lived without disease worsening or death for 11.7 months compared to 5.6 months for those receiving chemotherapy.”

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Osimertinib Approved in China for EGFR T790M+ NSCLC

Excerpt:

“The China Food and Drug Administration (CFDA) has approved osimertinib for the treatment of patients with locally-advanced or metastatic EGFR T790M-positive non–small cell lung cancer (NSCLC) with progression following treatment with an EGFR tyrosine kinase inhibitor (TKI).

“Osimertinib was approved under the CFDA’s accelerated Priority Review Pathway. To receive the treatment, patients must have their EGFR T790M mutation status confirmed through a validated test.”

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Tagrisso Demonstrates Superiority over Chemotherapy in EGFR T790M Mutation-Positive Non-Small Cell Lung Cancer

Excerpt:

“AstraZeneca today presented data from the AURA3 trial that data is supportive of Tagrisso (osimertinib) potentially becoming the new standard of care for 2nd-line treatment of patients with epidermal growth factor receptor (EGFR) T790M mutation-positive locally-advanced or metastatic non-small cell lung cancer (NSCLC). The first randomised Phase III data showed that Tagrisso 2nd-line therapy improved progression-free survival (PFS) by 5.7 months compared with standard platinum-based doublet chemotherapy (Hazard Ratio [HR]=0.3). The results were presented at the 17th World Conference on Lung Cancer (WCLC) in Vienna, Austria, hosted by the International Association for the Study of Lung Cancer, and published simultaneously online in The New England Journal of Medicine.”

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Biodesix®’ VeriStrat® Test Identifies T790M-Mutated Advanced Non-Small Cell Lung Cancer Patients Who Are More Likely to Have Improved Progression-Free Survival on Third Generation EGFR-TKI Therapy

Excerpt:

“Combined results from subset analyses of the TIGER-X and TIGER-2 clinical trials show that the VeriStrat test stratifies T790M-mutated patients with previously-treated, advanced non-small cell lung cancer (NSCLC) who are more or less likely to experience longer progression-free survival (PFS) when treated with a third-generation EGFR-TKI therapy. Clinical trial data suggesting the test’s potential for identifying better candidates for third-generation EGFR-TKI therapy were presented in Chicago last Friday at the at the IASLC Multidisciplinary Symposium in Thoracic Oncology hosted by the International Association for the Study of Lung Cancer.”

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ELCC 2016 Press Release: Osimertinib Given as First-line Treatment May Alter Biology of EGFR-Mutated Non-Small-Cell Lung Cancer

Excerpt:

“The third generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) osimertinib is effective in the first-line treatment of EGFR mutated non-small-cell lung cancer (NSCLC), according to a late-breaking abstract presented at the European Lung Cancer Conference (ELCC) 2016 in Geneva, Switzerland. A second late-breaking abstract confirms the drug’s effectiveness in patients with the T790M mutation.

“EGFR inhibition is the standard of care for NSCLC patients with EGFR activating mutations but nearly 50 to 60% develop resistance by developing a T790M mutation. Osimertinib is a potent inhibitor of the original EGFR mutations (exon 19 and exon 21) and the T790M. The study presented today investigated whether the use of osimertinib as first-line therapy for EGFR mutation positive NSCLC would result in favourable efficacy due to delayed T790M mediated resistance.

“The study included 60 patients from two phase I expansion cohorts of the AURA trial that had locally advanced or metastatic EGFR mutated NSCLC. Thirty patients received 80 mg a day and 30 received 160 mg a day in the first-line setting. The median follow-up was 16.6 months.”

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Clovis Oncology Announces Rociletinib New Drug Application Scheduled for Presentation at Upcoming FDA Oncologic Drugs Advisory Committee Meeting

“Clovis Oncology, Inc. (NASDAQ: CLVS) announced today that the U.S. Food and Drug Administration (FDA) has scheduled the New Drug Application (NDA) for rociletinib for discussion by the Oncologic Drugs Advisory Committee (ODAC) on April 12, 2016. Rociletinib is an investigational therapy for the treatment of patients with mutant epidermal growth factor receptor (EGFR) non-small cell lung cancer (NSCLC) who have been previously treated with an EGFR-targeted therapy and have the EGFR T790M mutation.

“The ODAC reviews and evaluates data concerning the safety and effectiveness of marketed and investigational human drug products for use in the treatment of cancer and makes recommendations to the FDA.

“ ‘We are actively preparing for this advisory committee meeting and look forward to the discussion about rociletinib,’ said Patrick J. Mahaffy, President and CEO of Clovis Oncology. ‘New treatments are needed for this hard-to-treat patient population, and we believe that rociletinib represents an important new option for patients with mutant EGFR T790M-positive lung cancer.’ “


High Response Rate Produced by Osimertinib in EGFR T790M-Mutant NSCLC

“Osimertinib (AZD9291), the third-generation TKI, demonstrated a 71% objective response rate (ORR) in those with EGFR T790M-mutant non-small cell lung cancer (NSCLC), following resistance to frontline anti-EGFR therapy, according the findings of the phase II AURA2 trial that was presented at this year’s World Conference on Lung Cancer (WCLC).

“The ORR consisted of 2 complete responses and 139 partial responses. The stable disease rate at ≥6 weeks was 21%, for a disease control rate of 92%. After a median follow-up of 6.7 months, the median progression-free survival (PFS) was 8.6 months. The median duration of response was 7.8 months (27% maturity).”


AstraZeneca Presents Further Evidence for the Potential of AZD9291 in First-Line and Pre-Treated Non-Small Cell Lung Cancer

“AstraZeneca today announced updated data on AZD9291 in first-line patients with epidermal growth factor receptor mutation (EGFRm) positive advanced non-small cell lung cancer (NSCLC) and previously-treated patients with EGFRm T790M mutation-positive NSCLC. The data being presented today at the World Conference on Lung Cancer (WCLC) 2015 were from the AURA Phase I trial first-line cohort and two AURA Phase II studies.

“Data demonstrated that in 60 patients who received AZD9291 once daily in the first-line setting, 72% (95% confidence interval (CI) 58% to 82%) were progression free (PFS) at 12 months. Confirmed overall response rate (ORR) was 75% (95% CI 62% to 85%). The longest duration of response (DoR) was ongoing at 18 months.

“ ‘While the data are still preliminary, these latest results from the AURA trial first-line cohort further reinforce the potential of AZD9291 in treatment-naïve EGFRm advanced NSCLC patients,’ said Professor Suresh S. Ramalingam, presenting author of the AURA trial first-line cohort data and Chief of Thoracic Oncology and Director of Medical Oncology, Emory University School of Medicine, Atlanta, GA, USA.”