US FDA approves Lilly’s Retevmo to treat adult patients with advanced RET-driven lung & thyroid cancers

Eli Lilly and Company announced that the US Food and Drug Administration (FDA) approved Retevmo (selpercatinib, 40 mg & 80 mg capsules), the first therapy specifically indicated for the treatment of adult patients with metastatic rearranged during transfection (RET) fusion-positive non-small cell lung cancer (NSCLC), and the treatment of adult and pediatric patients 12 years of age and older with advanced or metastatic RET-mutant medullary thyroid cancer (MTC) who require systemic therapy, or advanced or metastatic RET fusion-positive thyroid cancer who require systemic therapy and who are radioactive iodine-refractory (if radioactive iodine is appropriate).

Retevmo was approved under the FDA's Accelerated Approval regulations based on the LIBRETTO-001 phase 1/2 trial's endpoints of objective response rate (ORR) and duration of response (DoR). Continued approval for these indications may be contingent upon verification and description of clinical benefit in confirmatory trials.

Retevmo is a selective RET kinase inhibitor. Retevmo may affect both tumor cells and healthy cells, which can result in side effects. Retevmo is an oral prescription medicine, 120 mg or 160 mg based on weight, taken twice daily until disease progression or unacceptable toxicity.

"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," said Alexander Drilon, M.D., acting chief of early drug development at Memorial Sloan Kettering Cancer Center and lead investigator for LIBRETTO-001. "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. I am pleased that patients with these RET-driven cancers have this newly approved option."

Retevmo was evaluated in the single-arm, multi-center phase 1/2 LIBRETTO-001 trial, the largest trial (N=702) of patients with RET-driven cancers. The trial enrolled both treatment-naive patients and heavily pretreated patients with a variety of advanced solid tumors including RET fusion-positive NSCLC, RET-mutant MTC, RET fusion-positive thyroid cancer, and certain other solid tumors with RET alterations. Major efficacy outcomes were ORR and DoR, assessed by a blinded independent review committee. Prespecified secondary endpoints included central nervous system (CNS) ORR and CNS DoR.

Up to 50 per cent of patients with RET fusion-positive NSCLCs can have tumors that metastasize to the brain. Among previously treated NSCLC patients with measurable brain metastases, 10 out of 11 patients observed intracranial responses (CNS ORR), with all 10 patients experiencing a CNS DoR of greater than or equal to six months.

The labeling for Retevmo contains warnings and precautions for hepatotoxicity (evidence of liver dysfunction), hypertension, QT interval prolongation, hemorrhagic events, hypersensitivity, risk of impaired wound healing, and embryo-fetal toxicity.

In the LIBRETTO-001 trial, there was a five percent discontinuation rate due to adverse reactions (ARs). The most common ARs, including laboratory abnormalities, (=25 per cent) were increased aspartate aminotransferase (AST), increased alanine aminotransferase (ALT), increased glucose, decreased leukocytes, decreased albumin, decreased calcium, dry mouth, diarrhea, increased creatinine, increased alkaline phosphatase, hypertension, fatigue, edema (swelling in the arms or legs), decreased platelets, increased total cholesterol, rash, decreased sodium, and constipation. In addition, the most frequent serious AR (= 2 per cent) was pneumonia.

"RET alterations account for the majority of medullary thyroid cancers and a meaningful percentage of other 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," said Lori J. Wirth, M.D., medical director of head and neck cancers, Massachusetts General Hospital Cancer Center. "Based on the published data for this new medicine, as well as my personal experience treating patients, this may be a good treatment option."

"We are extremely proud of how quickly the combined Loxo Oncology and Lilly Oncology teams brought Retevmo to patients, further demonstrating our commitment to delivering life-changing medicines to people living with cancer," said Anne White, president of Lilly Oncology. "Retevmo entered clinical trials in May of 2017 and is now approved less than three years later, representing the most rapid timeline in the development of an oncology medicine with multiple indications. We applaud the FDA for their leadership and collaboration, recognizing the importance of bringing a new therapy to patients with advanced or metastatic RET-driven lung and thyroid cancers."

Retevmo should only be used in advanced or metastatic patients whose tumors have a RET fusion in NSCLC or thyroid cancer or a RET mutation in MTC. This can be determined through biomarker testing. Next-generation sequencing (NGS), either with tumor tissue biopsy or liquid biopsy, can be an appropriate biomarker test to determine actionable genomic alterations, including RET. If NGS is not available, RET can be detected using other biomarker testing methods. An FDA-approved test for the detection of RET fusions and RET mutations is not currently available. In LIBRETTO-001, identification of a RET gene alteration was prospectively determined in plasma or tumor tissue by local laboratories using NGS, PCR, or FISH. Immunohistochemistry was not used in the clinical trial.

"Increasingly, through the use of comprehensive biomarker testing, patients with metastatic cancer have an opportunity to receive a treatment tailored to the specific genomic nature of their tumor," said Andrea Ferris, president and chief executive officer at LUNGevity. "Retevmo represents an important new advance in this growing field, as the first therapy approved specifically for patients with RET-driven tumors. We urge patients to ask their doctors about broad biomarker tests that include RET alterations."

Retevmo was granted orphan drug designation by the FDA for the treatment of RET fusion-positive NSCLC and for the treatment of RET fusion-positive and RET-mutant thyroid cancers including poorly differentiated thyroid cancer, undifferentiated or anaplastic thyroid cancer, MTC and locally advanced or metastatic follicular or papillary thyroid cancer. The two confirmatory Phase 3 trials (LIBRETTO-431 and LIBRETTO-531) are currently enrolling patients.

Retevmo is expected to be available from specialty pharmacies within one week.

Retevmo (selpercatinib, formerly known as LOXO-292) (pronounced reh-TEHV-moh) is a selective and potent RET kinase inhibitor. Retevmo may affect both tumor cells and healthy cells, which can result in side effects. Retevmo is an oral prescription medicine, 120 mg or 160 mg dependent on weight (-/+ 50 kg), taken twice daily until disease progression or unacceptable toxicity.

Genomic alterations in the RET kinase, which include fusions and activating point mutations, lead to overactive RET signaling and uncontrolled cell growth. RET fusions have been identified in approximately 2 per cent of NSCLC; and 10-20 per cent of papillary, Hurthle cell, anaplastic, and poorly differentiated thyroid cancers. Activating RET point mutations account for approximately 60 percent of sporadic MTC and approximately 90 percent of germline MTC. RET fusion-positive cancers and RET-mutant MTC are primarily dependent on this single activated kinase for their proliferation and survival. This dependency, often referred to as "oncogene addiction," renders such tumors highly susceptible to small molecule inhibitors targeting RET. RET-driver alterations are predominantly mutually exclusive from other oncogenic drivers.

The LIBRETTO-001 Phase 1/2 trial was the largest clinical trial of patients with RET-driven cancers treated with a RET inhibitor. The trial included a dose escalation phase (phase 1) and a dose expansion phase (phase 2). The phase 2 portion of the trial had major efficacy outcomes of ORR and DoR, and prespecified secondary endpoints of CNS ORR and CNS DoR, as determined by an independent review committee according to Response Evaluation Criteria in Solid Tumors (RECIST v1.1). Results from the NSCLC population were last presented at the 2019 IASLC World Congress on Lung Cancer (WCLC), while results from the thyroid populations were last presented at the European Society for Medical Oncology (ESMO) 2019 Congress.



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