FDA Grants Tumor-Agnostic Accelerated Approval to RETEVMO®

SUMMARY: The FDA on September 21, 2022, granted accelerated approval to Selpercatinib (RETEVMO®) for adult patients with locally advanced or metastatic solid tumors with a Rearranged during Transfection (RET) gene fusion that have progressed on or following prior systemic treatment, or who have no satisfactory alternative treatment options. The FDA on the same day also granted Regular approval to Selpercatinib for adult patients with locally advanced or metastatic Non Small Cell Lung Cancer (NSCLC) with a Rearranged during Transfection (RET) gene fusion, as detected by an FDA-approved test. FDA also approved the Oncomine Dx Target (ODxT) Test as a companion diagnostic for Selpercatinib.

In addition to the well characterized gene fusions involving ALK and ROS1 in NSCLC, genetic alterations involving other kinases including EGFR, BRAF, RET, NTRK, are all additional established targetable drivers. These genetic alterations are generally mutually exclusive, with no more than one predominant driver in any given cancer. The hallmark of all these genetic alterations is oncogene addiction, in which cancers are driven primarily, or even exclusively, by aberrant oncogene signaling, and are highly susceptible to small molecule inhibitors.

RET kinase is a transmembrane Receptor Tyrosine Kinase and plays an important role during the development and maintenance of a variety of tissues, including neural and genitourinary tissues. RET signaling activates downstream pathways such as JAK/STAT3 and RAS/RAF/MEK/ERK and leads to cellular proliferation, survival, invasion, and metastasis. Oncogenic alterations to the RET proto-oncogene result in uncontrolled cell growth and enhanced tumor invasiveness. RET alterations include RET rearrangements, leading to RET fusions, and activating point mutations occurring across multiple tumor types. RET fusions have been identified in approximately 2% of NSCLCs, 10-20% of non-medullary thyroid cancers. Activating RET point mutations account for approximately 60% of sporadic Medullary Thyroid Cancers (MTC) and more than 90% of inherited MTCs. Other cancers with documented RET alterations include colorectal, pancreas, breast, and several hematologic malignancies.

Selpercatinib is a highly selective and potent, oral anti-RET Tyrosine Kinase Inhibitor (TKI) designed to inhibit native RET signaling, as well as anticipated acquired resistance mechanisms. Selpercatinib selectively targets wild-type RET as well as various RET mutants and RET-containing fusion products. Additionally, Selpercatinib inhibits Vascular Endothelial Growth Factor Receptor 1 (VEGFR1), VEGFR3, Fibroblast Growth Factor Receptor 1 (FGFR1), FGFR2, and FGFR3. This results in inhibition of cell growth of tumors that exhibit increased RET activity.

The LIBRETTO-001 is the largest open-label, multicenter, Phase I/II trial in patients with advanced solid tumors, including RET fusion-positive solid tumors, RET-mutant Medullary Thyroid Cancers, and other tumors with RET activation, treated with a RET inhibitor. To investigate the efficacy of Selpercatinib, the trial was conducted in 2 parts: Phase 1 (dose escalation) and Phase II (dose expansion). Patients with advanced cancer were eligible, if they have progressed on or were intolerant to available standard therapies, or no standard or available curative therapy existed, or in the opinion of the Investigator, they would be unlikely to tolerate or derive significant clinical benefit from appropriate standard of care therapy, or they declined standard therapy. A dose of 160 mg BID was the recommended Phase II dose. Up to about 850 patients with advanced solid tumors harboring a RET gene alteration in tumor and/or blood were enrolled in 6 different Phase II cohorts, based on tumor type, RET alteration and prior therapy. Identification of RET gene alterations were prospectively determined in local laboratories using either Next Generation Sequencing, Polymerase Chain Reaction, or Fluorescence In Situ Hybridization. The Phase II portion of the trial had a Primary endpoint of Objective Response Rate (ORR) by Blinded Independent Review Committee (BIRC) and Secondary endpoints of Duration of Response, CNS Objective Response Rate, Progression Free Survival (PFS) and safety.

RET Fusion-Positive Solid Tumors

This group included 41 patients and the most common cancers were pancreatic adenocarcinoma (27%), colorectal (24%), salivary (10%), and unknown primary (7%). Majority of the patients (90%) received 2 prior systemic therapies and 32% had received 3 or more. The median age of patients was 50 years, 54% were female, 68% were White, 24% were Asian, and 95% had metastatic disease. RET fusion-positive status was detected in 98% of patients using NGS and 2% using FISH.

The Objective Response Rate was 44%, with 5% Complete Response and 39% Partial Response. The median Duration of response was 24.5 months and 67% of patients had a Duration of Response of 6 months or more.

The NSCLC Cohort

Selpercatinib was previously granted accelerated approval in May 2020 for patients with metastatic RET fusion-positive NSCLC based on initial Overall Response Rate (ORR) and Duration of Response (DOR) among 144 patients enrolled in the LIBRETTO-001 trial. The conversion to regular and traditional FDA approval was based on data from an additional 172 patients and 18 months of additional follow up, to assess durability of response. Patients received Selpercatinib until disease progression or unacceptable toxicity and efficacy was evaluated in a total of 316 patients with locally advanced or metastatic RET fusion-positive NSCLC. The median age of patients was 61 years, 58% were female, 49% were White, 41% were Asian and 97% had metastatic disease. Previously treated patients received a median of two prior systemic therapies and 58% had received prior anti PD 1/PD-L1 therapy.

Among the 69 treatment-naïve patients, the ORR was 84%, with 6% Complete Response and 78% Partial Response. The median Duration of Response was 20.2 months and 50% of patients had a Duration of Response of 12 months or more. Among the 247 previously treated patients, the ORR was 61%, with 7% Complete Response and 54% Partial Response. The median Duration of Response was 28.6 months and 63% of patients had a Duration of Response of 12 months or more.

It is estimated that up to 50% of RET fusion-positive NSCLC patients can have brain metastases, and in the subset of patients with brain metastases (N=21), treatment with Selpercatinib demonstrated a CNS Objective Response Rate of 85%, and 38% of responders had an intracranial Duration of Response of 12 months or greater. The most common toxicities in patients were edema, diarrhea, fatigue, dry mouth, hypertension, abdominal pain, constipation, rash, nausea, and headache.

LIBRETTO-001 is the largest trial ever reported in RET-altered cancer patients and represents an important milestone in the Precision Medicine arena. Selpercatinib is the first and only RET inhibitor to receive both tumor-agnostic accelerated approval and traditional approval in NSCLC, reinforcing its benefits across diverse tumor types.

Selpercatinib in patients with RET fusion–positive non–small-cell lung cancer: updated safety and efficacy from the registrational libretto-001 phase I/II trial.Published September 19, 2022. Drilon A, Subbiah V, Gautschi O, et al. J Clin Oncol. doi:10.1200/JCO.22.00393

https://www.fda.gov/drugs/resources-information-approved-drugs/fda-approves-selpercatinib-locally-advanced-or-metastatic-ret-fusion-positive-solid-tumors

GAVRETO® (Pralsetinib)

The FDA on December 1, 2020 approved GAVRETO®, for 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 RET fusion-positive thyroid cancer who require systemic therapy and who are Radioactive Iodine-refractory (if Radioactive Iodine is appropriate). GAVRETO® is a product of Blueprint Medicines Corporation.

FDA Approves RETEVMO® for RET Altered Non Small Cell Lung Cancer and Thyroid Cancers

SUMMARY: The FDA on May 8, 2020, granted accelerated approval to RETEVMO® (Selpercatinib) for patients with metastatic RET fusion-positive Non-Small Cell Lung Cancer (NSCLC), patients with advanced or metastatic RET-mutant Medullary Thyroid Cancer (MTC) who require systemic therapy and those with advanced or metastatic RET fusion-positive thyroid cancer who require systemic therapy and who are RadioActive Iodine (RAI)-refractory. Lung cancer is the second most common cancer in both men and women and accounts for about 14% of all new cancers and 27% of all cancer deaths. The American Cancer Society estimates that for 2020, about 228, 820 new cases of lung cancer will be diagnosed and 135,720 patients will die of the disease. Lung cancer is the leading cause of cancer-related mortality in the United States. Non-Small Cell Lung Cancer (NSCLC) accounts for approximately 85% of all lung cancers.

In addition to the well characterized gene fusions involving ALK and ROS1 in NSCLC, genetic alterations involving other kinases including EGFR, BRAF, RET, NTRK, are all additional established targetable drivers. These genetic alterations are generally mutually exclusive, with no more than one predominant driver in any given cancer. The hallmark of all of these genetic alterations is oncogene addiction, in which cancers are driven primarily, or even exclusively, by aberrant oncogene signaling, and are highly susceptible to small molecule inhibitors.MOA-of-RETEVMO

RET kinase is a transmembrane Receptor Tyrosine Kinase and plays an important role during the development and maintenance of a variety of tissues, including neural and genitourinary tissues. RET signaling activates downstream pathways such as JAK/STAT3 and RAS/RAF/MEK/ERK and leads to cellular proliferation, survival, invasion, and metastasis. Oncogenic alterations to the RET proto-oncogene results in uncontrolled cell growth and enhanced tumor invasiveness. RET alterations include RET rearrangements, leading to RET fusions, and activating point mutations occurring across multiple tumor types. RET fusions have been identified in approximately 2% of NSCLCs, 10-20% of non-medullary thyroid cancers. Activating RET point mutations account for approximately 60% of sporadic Medullary Thyroid Cancers (MTC) and more than 90% of inherited MTCs. Other cancers with documented RET alterations include colorectal, breast, and several hematologic malignancies.

RETEVMO® (Selpercatinib) is a highly selective and potent, oral anti-RET Tyrosine Kinase Inhibitor (TKI) designed to inhibit native RET signaling, as well as anticipated acquired resistance mechanisms. RETEVMO® selectively targets wild-type RET as well as various RET mutants and RET-containing fusion products. Additionally, RETEVMO® inhibits Vascular Endothelial Growth Factor Receptor 1 (VEGFR1), VEGFR3, Fibroblast Growth Factor Receptor 1 (FGFR1), FGFR2, and FGFR3. This results in inhibition of cell growth of tumors that exhibit increased RET activity.

The LIBRETTO-001 is the largest open-label, multicenter, Phase I/II trial in patients with advanced solid tumors, including RET fusion-positive solid tumors, RET-mutant Medullary Thyroid Cancers, and other tumors with RET activation, treated with a RET inhibitor. To investigate the efficacy of RETEVMO®, the trial was conducted in 2 parts: Phase 1 (dose escalation) and Phase II (dose expansion). Patients with advanced cancer were eligible, if they have progressed on or were intolerant to available standard therapies, or no standard or available curative therapy existed, or in the opinion of the Investigator, they would be unlikely to tolerate or derive significant clinical benefit from appropriate standard of care therapy, or they declined standard therapy. A dose of 160 mg BID was the recommended Phase II dose. Up to about 850 patients with advanced solid tumors harboring a RET gene alteration in tumor and/or blood were enrolled in 6 different Phase II cohorts, based on tumor type, RET alteration and prior therapy. Identification of RET gene alterations was prospectively determined in local laboratories using either Next Generation Sequencing, Polymerase Chain Reaction, or Fluorescence In Situ Hybridization. The Phase II portion of the trial had a Primary endpoint of Objective Response Rate (ORR) and Secondary endpoints of Duration of Response, Progression Free Survival (PFS) and safety.

The NSCLC cohort included 105 enrolled patients with RET fusion-positive NSCLC who had received prior platinum-based chemotherapy. Patients had received a median of three prior systemic regimens, 55% had previous treatment with an anti-PD-1/PD-L1 antibody and 48% had previous treatment with at least one multikinase inhibitor. The ORR with RETEVMO&reg was 64%, and 81% of responding patients had responses lasting 6 months or longer. Efficacy was also evaluated in 39 treatment-naïve patients. The ORR for these patients with RETEVMO&reg was 85%, and 58% of responding patients had responses lasting 6 months or longer. It is estimated that up to 50% of RET fusion-positive NSCLC patients can have brain metastases, and in the subset of patients with brain metastases in this registrational trial, treatment with RETEVMO&reg demonstrated a CNS Objective Response Rate of 91%. Median DOR and PFS were not reached at the time of data-cut-off.

In the cohort of advanced or metastatic RET-mutant MTC (N=143), the ORR in patients previously treated with COMETRIQ® (Cabozantinib), CAPRELSA® (Vandetanib), or both (N=55) was 69%, and 76% of responding patients had responses lasting 6 months or longer. Among those patients who had no prior therapy with an approved agent for MTC (N=88), the ORR was 73%, and 61% of responding patients had responses lasting 6 months or longer.

In the cohort of RET fusion-positive thyroid cancer who were RAI-refractory and had received another prior systemic treatment (N=19), the ORR was 79%, and 87% of responders had a response lasting 6 months or longer. Among the patients with RET fusion-positive thyroid cancer who were RAI-refractory and had not received any additional therapy (N=8), the ORR was 100% and 75% of responders had a response lasting 6 months or longer.The most common toxicities included rash, cytopenias, liver function abnormalities, hyperglycemia, hyponatremia, hypocalcemia, increased creatinine and hypertension.

LIBRETTO-001 is the largest trial ever reported in RET-altered cancer patients, and the present FDA approval of RETEVMO® for patients with RET fusions and mutations, across multiple tumor types, represents an important milestone in the Precision Medicine arena.

https://www.fda.gov/drugs/drug-approvals-and-databases/fda-approves-selpercatinib-lung-and-thyroid-cancers-ret-gene-mutations-or-fusions

RETEVMO® (Selpercatinib)

The FDA on May 8, 2020, granted accelerated approval to RETEVMO® for the following indications:

1) Adult patients with metastatic RET fusion-positive Non-Small Cell Lung Cancer (NSCLC).

2) Adult and pediatric patients 12 years of age or older with advanced or metastatic RET-mutant Medullary Thyroid Cancer (MTC) who require systemic therapy.

3) Adult and pediatric patients 12 years of age or older with advanced or metastatic RET fusion-positive thyroid cancer who require systemic therapy, and who are Radioactive Iodine-refractory (if Radioactive Iodine is appropriate).

RETEVMO® is a product of Eli Lilly and Company.

COMETRIQ® (Cabozantinib)

The FDA on November 29, 2012 approved COMETRIQ® for the treatment of patients with progressive metastatic medullary thyroid cancer (MTC). COMETRIQ®  is a small molecule that inhibits the activity of multiple tyrosine kinases, including RET, MET, and VEGF receptor 2. COMETRIQ® is available in capsule form and is a product of  Exelixis, Inc.

Oncoprescribe Blog Vandetanib (Zactima) in Medullary Thyroid Cancer

Medullary Thyroid Cancer accounts for about 6% of all thyroid cancers. This cancer originates from the parafollicular cells, also called C cells, of the thyroid. Calcitonin is a hormone produced by the C cells. For this reason, measuring serum calcitonin following complete resection of Medullary Thyroid Carcinoma can be helpful in diagnosing recurrent disease.

There is presently no active treatment approved by the FDA,  for the treatment of advanced Medullary Thyroid Carcinoma (MTC). A new oral Tyrosine Kinase Inhibitor (Vandetanib) has shown promising results and may soon become available. This agent is a dual inhibitor and targets the epidermal growth factor receptor (EGFR) and vascular endothelial growth factor receptor (VEGFR). It also appears to inhibit RET-tyrosine kinase activity, an important  driver of cell growth in MTC.

Results from a double blind phase III trial (ZETA study) presented at ASCO 2010, showed that treatment with Vandetanib significantly extended progression free survival with a 54% reduction in the rate of disease progression compared to placebo.

Vandetanib (Zactima) is very likely to be studied in other solid tumors given its ability to target multiple receptors. Stay Tuned.