Capmatinib produced rapid, deep responses in patients with advanced non–small cell lung cancer (NSCLC) harboring MET exon 14 (METex14) skipping mutations, according to a presentation at the AACR virtual meeting I.
The duration of response was impressive in both treatment-naive and previously treated patients, according to presenter Edward B. Garon, MD, of the University of California, Los Angeles.
In view of these responses, Dr. Garon urged early molecular testing in NSCLC.
He also noted that capmatinib produced responses in patients with brain metastases. However, because of small patient numbers, additional study is needed to validate the intracranial efficacy of capmatinib and ascertain mechanisms of resistance.
Study Rationale and Details
Capmatinib is a highly selective, reversible, and potent inhibitor of MET tyrosine kinase that crosses the blood-brain barrier.
In the phase 2 GEOMETRY mono-1 study, Dr. Garon and colleagues tested capmatinib, given at 400 mg orally twice a day, in patients with METex14-mutated, ALK, and EGFR wild-type, stage IIIB/IV NSCLC. Patients with neurologically stable or asymptomatic brain metastases were eligible.
Dr. Garon presented safety data for all patients enrolled in this study and efficacy data for patients in cohorts 4 and 5b. Cohort 4 enrolled patients who received prior systemic therapy for advanced disease, and cohort 5b enrolled treatment-naive patients. Both cohorts had METex14 gene mutations but not amplification.
There were 97 patients evaluable for efficacy – 69 previously treated and 28 treatment naive. The median age in both cohorts was 71 years, most patients were female (58% of previously treated and 64.3% of treatment-naive patients), and most were never-smokers (58% and 64.3%, respectively). Adenocarcinoma was the predominant histology.
The overall response rate, per an independent review committee, was 40.6% in previously treated patients and 67.9% in treatment-naive patients.
Waterfall plots showed deep responses, with only four cases of disease progression in the previously treated cohort and none in the treatment-naive cohort.
Responses occurred rapidly. Many responses exceeded 1 year and were ongoing at the data cut-off. The median response duration was 9.72 months in previously treated patients and 11.14 months in treatment-naive patients.
There were 13 patients with evaluable baseline brain metastases (3.3 brain lesions per patient [range, 1-8]). Twelve patients had intracranial disease control, and seven patients (54%) had intracranial response. Four patients had complete resolution of all brain lesions.
Intracranial responses were generally seen by the first radiologic evaluation and occurred as rapidly as systemic responses.
With safety data on all 334 patients in the trial, the GEOMETRY mono-1 study is the largest reported experience with capmatinib in NSCLC patients. The median treatment exposure time was 14.9 weeks.
Overall, 35.6% of patients experienced a grade 3/4 adverse event (AE). Grade 4 AEs were observed in 4.5% of patients, and there were no treatment-related deaths.
Peripheral edema (41.6%), nausea (33.2%), increased blood creatinine (19.5%), and vomiting (18.9%) were the most frequent AEs of any grade.
In all, 21.9% of patients required dose adjustments due to treatment-related AEs, and 11.1% of patients stopped treatment because of an AE.
This study was sponsored by Novartis. Dr. Garon disclosed relationships with Novartis, AstraZeneca, Bristol-Myers Squibb, Dracen, Dynavax, Eli Lilly, EMD Serono, Genentech, GSK, Iovance, Merck, Mirati, and Neon.
Dr. Lyss was a community-based medical oncologist and clinical researcher for more than 35 years before his recent retirement. His clinical and research interests were focused on breast and lung cancers as well as expanding clinical trial access to medically underserved populations. He is based in St. Louis. He has no conflicts of interest.
SOURCE: Garon EB et al. AACR 2020, Abstract CT082.
This story originally appeared on MDedge.com.
Selpercatinib (Retevmo, Loxo/Lilly) becomes the first targeted therapy to be approved by the US Food and Drug Administration (FDA) for use in patients with cancer who have certain tumors that have an alteration (mutation or fusion) in the RET gene.
The drug is indicated for use in RET-positive tumors found in the following:
Non–small cell lung cancer (NSCLC) that has spread in adult patients;
Advanced medullary thyroid cancer (MTC) or MTC that has spread in adult and pediatric patients (older than 12 years) who require systemic therapy; and
Thyroid cancer that requires systemic therapy and that has stopped responding to or is not appropriate for radioactive iodine therapy in adult and pediatric (older than 12 years) patients.
Before initiating treatment, an RET gene alteration must be determined via laboratory testing, the agency emphasized. However, no FDA-approved test is currently available for detecting RET fusions/mutations.
Approval Based on Reponses in Open-Label Trial
This was an accelerated approval based on the overall response rate (ORR) and duration of response (DOR) seen in an open-label clinical trial (the phase 1/2 LIBRETTO-001 study), which involved patients with each of the three types of tumors.
All patients received selpercatinib 160 mg orally twice daily until disease progression or unacceptable toxicity occurred.
The company notes that for this trial, identification of an RET gene alteration was prospectively determined in plasma or tumor tissue by local laboratories using next-generation sequencing, polymerase chain reaction testing, or fluorescence in situ hybridization. Immunohistochemistry was not used in the clinical trial.
Efficacy for NSCLC was evaluated in 105 adult patients with RET fusion-positive NSCLC who were previously treated with platinum chemotherapy. The ORR was 64%.
It was also evaluated in 39 patients with RET fusion-positive NSCLC who had not received any previous treatment. The ORR for these patients was 84%.
For both groups, among patients who responded to treatment, the response lasted more than 6 months.
In a company press release, LIBRETTO-001 lead investigator Alexander Drilon, MD, acting chief of early drug development at Memorial Sloan Kettering Cancer Center, New York City, said: "In the clinical trial, we observed that the majority of metastatic lung cancer patients experienced clinically meaningful responses when treated with selpercatinib, including responses in difficult-to-treat brain metastases.
"The approval of selpercatinib marks an important milestone in the treatment of NSCLC, making RET-driven cancers now specifically targetable in the same manner as cancers with activating EGFR and ALK alterations, across all lines of therapy," he added.
About 1% to 2% of NSCLC tumors are thought to have an RET alteration.
The same trial also included patients with thyroid cancer.
Efficacy for MTC was evaluated in 55 adult and pediatric (older than 12 years) patients with advanced or metastatic RET-mutant MTC who had previously been treated with cabozantinib, vandetanib, or both. The ORR was 69%.
In addition, the drug was evaluated in 88 patients with advanced or metastatic RET-mutant MTC who had not received prior treatment with cabozantinib or vandetanib. The ORR for these patients was 73%.
The trial also enrolled 19 patients with RET-positive thyroid cancer whose condition was refractory to radioactive iodine (RAI) treatment and who had received another prior systemic treatment. The ORR was 79%. Eight patients had received only RAI. The ORR for these patients was 100%.
In all the cases of thyroid cancer and lung cancer, among the patients who responded to treatment, the response lasted longer than 6 months.
"RET alterations account for the majority of medullary thyroid cancers and a meaningful percentage of other thyroid cancers," Lori J. Wirth, MD, medical director of head and neck cancers, Massachusetts General Hospital Cancer Center, Boston, noted in the company release.
A fact sheet from the company notes that RET mutations are found in about 60% of sporadic MTC cases and in over 90% of familial MTC cases, and that RET fusions are found in approximately 10% to 20% of papillary thyroid cancers.
"For patients living with these cancers, the approval of selpercatinib means they now have a treatment option that selectively and potently inhibits RET," Wirth commented. "Based on the published data for this new medicine, as well as my personal experience treating patients, this may be a good treatment option."
In the LIBRETTO-001 trial, the rate of discontinuations because of adverse reactions (ARs) was 5%, the company reported. The most common ARs, including laboratory abnormalities (≥25%), were increased aspartate aminotransferase level, increased alanine aminotransferase level, increased glucose level, decreased leukocyte count, decreased albumin level, decreased calcium level, dry mouth, diarrhea, increased creatinine level, increased alkaline phosphatase level, hypertension, fatigue, edema, decreased platelet count, increased total cholesterol level, rash, decreased sodium levels, and constipation. The most frequent serious AR (≥2%) was pneumonia.
The FDA warned that selpercatinib can cause hepatotoxicity, elevation in blood pressure, QT prolongation, bleeding, and allergic reactions. It may also be toxic to a fetus or newborn baby so should not be taken by pregnant or breastfeeding women.
The drug is currently being assessed in two phase 3 confirmatory trials. LIBRETTO-431 will test the drug in previously untreated patients with RET-positive NSCLC. LIBRETTO-531 involves treatment-naive patients with RET-positive MTC.
The company that developed selpercaptinib, Loxo Oncology, was acquired by Eli Lilly last year in an $8 billion takeover. This drug was billed as the most promising asset in that deal, alongside oral BTK inhibitor LOXO-305, comments a report in Pharmaphorum.
Loxo developed Vitrakvi (larotrectinib), the first TRK inhibitor to reach the market, as well as the follow-up drug LOXO-195. Both were acquired by Bayer ahead of the Lilly takeover, that report notes.
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