Response to Selpercatinib in a Patient With Recurrent Glioblastoma and RET Amplification

Rapid response to selpercatinib in RET fusion positive pancreatic neuroendocrine carcinoma confirmed by smartwatch

This case report describes the efficacy of selpercatinib, a selective RET inhibitor, in an unusual case of large-cell neuroendocrine pancreatic carcinoma (LCNEPAC) harboring a CCDC6::RET fusion. A 56-year-old male with a history of multiple lines of systemic therapies exhibited marked clinical amelioration shortly after initiating selpercatinib within the LOXO-RET-17001 study (ClinicalTrials.gov ID: NCT03157128, first posted: 2017-05-17). Data from the patient's smartwatch suggested early efficacy before conventional methods, such as serum tumor markers and CT imaging confirmed the antitumor activity. This case not only underscores the efficacy of selpercatinib in treating RET fusion-positive rare tumors but also highlights the potential of wearable technology in cancer care. In conclusion, the standard readings from commercially available wearable devices can be useful for the monitoring of treatment response to targeted therapy and may serve as digital biomarkers in clinical trials. This approach marks a significant advancement in patient-centric healthcare, leveraging technology to enhance the effectiveness and precision of treatment evaluation.

Impact of tissue-agnostic approvals on management of primary brain tumors

Novel tissue-agnostic therapeutics targeting driver mutations in tumor cells have been recently approved by FDA, driven by basket trials that have demonstrated their efficacy and safety across diverse tumor histology. However, the relative rarity of primary brain tumors (PBTs) has limited their representation in early trials of tissue-agnostic medications. Thus, consensus continues to evolve regarding utility of tissue-agnostic medications in routine practice for PBTs, a diverse group of neoplasms characterized by limited treatment options and unfavorable prognoses. We describe current and potential impact of tissue-agnostic approvals on management of PBTs. We discuss data from clinical trials for PBTs regarding tissue-agnostic targets, including BRAFV600E, neurotrophic tyrosine receptor kinase (NTRK) fusions, microsatellite instability-high (MSI-High), mismatch repair deficiency (dMMR), and high tumor mutational burden (TMB-H), in context of challenges in managing PBTs. Described are additional tissue-agnostic targets that hold promise for benefiting patients with PBTs, including RET fusion, fibroblast growth factor receptor (FGFR), ERBB2/HER2, and KRASG12C, and TP53Y220C.

Amplification of Wild-Type RET Represents a Novel Molecular Subtype of Several Cancer Types With Clinical Response to Selpercatinib

PURPOSE

RET rearrangements and RET activating point mutations represent targetable genomic alterations in advanced solid tumors. However, the frequency and clinicopathologic characteristics of wild-type RET amplification in cancer and its potential role as a targetable oncogenic driver are not well-characterized.

METHODS

In two institutional cohorts of patients with solid cancers from the Dana-Farber Cancer Institute (DFCI) and Memorial Sloan Kettering Cancer Center (MSKCC) whose tumors underwent next-generation sequencing (NGS), the frequency and clinicopathologic features of wild-type RET amplification in the absence of RET rearrangements or activating mutations was assessed. The findings were validated using merged data from The Cancer Genome Atlas (TCGA), Genomics Evidence Neoplasia Information Exchange (GENIE), and China Pan-Cancer data sets.

RESULTS

The frequency of wild-type RET amplification across all solid cancers was 0.08% (26 of 32,505) in the DFCI cohort, 0.05% (26 of 53,152) in the MSKCC cohort, and 0.25% (71 of 28,623) in the cohort from TCGA, GENIE, and China Pan-Cancer. Cancer types with RET amplification included non-small-cell lung cancer (NSCLC), hepatobiliary cancer, prostate cancer, breast cancer, and others. The median RET copy number in RET-amplified cases was 7.5 (range, 6-36) in the DFCI cohort and 5.7 (range, 4-27.7) in the MSKCC cohort. Among 11 RET-amplified NSCLCs, eight had no other concurrent driver mutations. Finally, we report on a 69-year-old man with recurrent NSCLC harboring high-level wild-type RET amplification (22-28 copies) as the only identified putative genomic driver who experienced both a systemic and intracranial confirmed response to the RET inhibitor selpercatinib.

CONCLUSION

Amplification of wild-type RET represents a novel, targetable molecular subset of cancer.

RET-Altered Cancers-A Tumor-Agnostic Review of Biology, Diagnosis and Targeted Therapy Activity

RET alterations, such as fusions or mutations, drive the growth of multiple tumor types. These alterations are found in canonical (lung and thyroid) and non-canonical (e.g., gastrointestinal, breast, gynecological, genitourinary, histiocytic) cancers. RET alterations are best identified via comprehensive next-generation sequencing, preferably with DNA and RNA interrogation for fusions. Targeted therapies for RET-dependent cancers have evolved from older multikinase inhibitors to selective inhibitors of RET such as selpercatinib and pralsetinib. Prospective basket trials and retrospective reports have demonstrated the activity of these drugs in a wide variety of RET-altered cancers, notably those with RET fusions. This paved the way for the first tumor-agnostic selective RET inhibitor US FDA approval in 2022. Acquired resistance to RET kinase inhibitors can take the form of acquired resistance mutations (e.g., RET G810X) or bypass alterations.