Sustained Clinical Response to 4th-Line Therapy with Selpercatinib in RET Fusion-Positive Combined Small Cell Lung Cancer

Objective

Combined small cell lung cancer (C-SCLC) is a relatively rare subtype of small cell lung cancer (SCLC) which combines SCLC and any component of non-small cell carcinoma (NSCLC). Patients diagnosed with C-SCLC are currently recommended to receive the same treatment as SCLC cases in the absence of clear evidence suggesting different strategies. The genomic profiling of C-SCLC is rarely studied. Herein, we report a case of extensive-stage C-SCLC harboring the KIF5B-RET fusion before first-line therapy and with persistent sensitivity to fourth-line selpercatinib treatment is reported.

Materials and Methods

Molecular and pathological features were evaluated using transbronchial lung biopsy, immunohistochemical (IHC) staining and next-generation sequencing (NGS).

Results

NGS revealed the KIF5B-RET fusion in the C-SCLC tumor. The patient had a progression-free survival (PFS) surpassing 14 months after selpercatinib treatment, with ongoing clinical response in 4th-line treatment.

Conclusion

This case highlights the importance of comprehensive molecular testing in C-SCLC for selecting the optimal treatment. Although RET fusion is rare in patients with C-SCLC, its identification and treatment with selective RET inhibitors may contribute to clinical benefits.

Selpercatinib monotherapy in a Chinese patient with RET fusion/ EGFR co-mutated nonsmall cell lung cancer from the Phase II LIBRETTO-321 study: a case report

Rearranged during transfection ( RET ) fusions and epidermal growth factor receptor ( EGFR ) mutations are potent oncogenic drivers in patients with nonsmall cell lung cancer (NSCLC), but rarely co-exist. Concurrent RET/EGFR mutations have been reported in patients with NSCLC who develop resistance to EGFR tyrosine kinase inhibitors but are even less frequent in treatment-naïve patients. Consequently, there is no standard treatment for RET/EGFR -mutated NSCLC. We report a case of RET/EGFR mutant NSCLC successfully treated with the oral, potent, highly selective RET inhibitor selpercatinib (160 mg daily for 28-day cycles) in an ongoing phase II study in Chinese patients with NSCLC (LIBRETTO-321). The patient, a female nonsmoker, was diagnosed with de-novo left lung adenocarcinoma with neuroendocrine differentiation, and a RET fusion was detected by next-generation sequencing testing. The patient had two tumors in the pleura, a third in the subcarinal lymph node, and a nontarget tumor in the pleura. Pleural biopsy analysis confirmed a RET fusion KIF5B (K15;R12) and an EGFR exon 19 deletion. The patient achieved a partial response (PR) with selpercatinib (absence of target tumors in pleura and reduction in the size of lymph node tumor). The PR persisted for 14.7 months, with disease progression in the nontarget lesion in the pleura and a new lesion in the liver (the PR had persisted), resulting in the discontinuation of selpercatinib. The only notable adverse event was grade 3 elevated transaminase, that was effectively managed by dose reduction. These data may support the use of selpercatinib in patients with RET/EGFR co-mutated NSCLC.

GDNF regulates lipid metabolism and glioma growth through RET/ERK/HIF‑1/SREBP‑1

Cancer cells rewire their metabolism to meet the demands of growth and survival and this metabolic reprogramming has been recognized as an emerging hallmark of cancer. However, the respective mechanisms remain elusive and the contribution of aberrant lipid metabolism to the malignant phenotypes of glioma are unclear. The present study demonstrated that glial-derived neurotrophic factor (GDNF) is highly expressed in glioma and associated with poor clinical outcomes. In addition, there was a significant correlation between GDNF/rearranged during transfection (RET)/ERK signaling and sterol regulatory element-binding protein-1 (SREBP-1) expression in glioma cells. Pharmacological or genetic inhibition of GDNF-induced RET/ERK activity downregulated SREBP-1 expression and SREBP-1-mediated transcription of lipogenic genes. Additionally, GDNF regulated SREBP-1 activity by promoting hypoxia-inducible factor-1α (HIF-1α) mediated glucose absorption and hexosamine biosynthetic pathway mediated SREBP cleavage-activating protein N-glycosylation. In addition, the inhibition of SREBP-1 reduced the in vitro GDNF-induced glioma cell proliferation. The results elucidated the complex relationship between GDNF/RET/ERK signaling and dysregulated glycolipid-metabolism, which shows great potential to uncover novel metabolic vulnerabilities and improve the efficacy of targeted therapies.

A contemporary review of rearranged during transfection-selective inhibitors

OBJECTIVE

Rearranged during transfection genes are present in 1-2% of patients who have non-small cell lung cancer and 10-30% of patients with papillary thyroid cancer. The objective of this article is to review the current rearranged during transfection inhibitors indicated for patients with rearranged during transfection-mutated cancers and their future directions.Data sources: The pivotal phase I/II studies for selpercatinib and pralsetinib were evaluated. Current studies on rearranged during transfection inhibitors were searched on ClinicalTrials.gov using the key word "RET."Data summary: Selpercatinib and pralsetinib were the first two U.S. Food and Drug Administration-approved rearranged during transfection-selective inhibitors for advanced or metastatic rearranged during transfection fusion-positive non-small cell lung cancer, rearranged during transfection-mutant medullary thyroid cancer, and rearranged during transfection fusion-positive thyroid cancer. Both agents showed promising efficacy with objective response rate ranging from 60% to 73% in all aforementioned rearranged during transfection-mutated cancers. Additionally, benefits were seen even in patients with intracranial metastasis at baseline. Both showed favorable safety profiles. Some common class adverse events included elevated liver function tests and hypertension. Hematologic side effects such as anemia and neutropenia were more common with pralsetinib. Selpercatinib had interactions with acid suppressive therapy and specific instructions when used concomitantly.

CONCLUSIONS

While the rearranged during transfection inhibitors are generally well-tolerated, each agent possesses slightly different efficacy, side-effect profile, and drug-drug interactions.

Efficacy of immune checkpoint inhibitor therapy in patients with RET fusion-positive non-small-cell lung cancer

Aim: To describe outcomes of patients with rearraned during transfection (RET) fusion-positive non-small-cell lung cancer (NSCLC) who received immune checkpoint inhibitor (ICI)-based treatments in the US. Patients & methods: Using de-identified Flatiron Health-Foundation Medicine NSCLC Clinico-Genomic and Guardant Health databases, treatment patterns and outcomes of 69 patients with advanced/metastatic RET fusion-positive NSCLC who received ICI-based treatment were described. Results: Median real-world progression-free survival and overall survival months were 4.2 (95% CI: 1.4-8.4) and 19.1 (6.9-not reached), respectively, among patients in Clinico-Genomic database (n = 17) receiving first-line ICI-based therapy. In the Guardant Health database, progression-free survival was unavailable, and the median overall survival was not reached (n = 29). Conclusion: Outcomes associated with ICI-based treatments in the first-line setting among patients with RET fusion-positive NSCLC are consistent with unselected populations reported in literature.

GDNF, A Neuron-Derived Factor Upregulated in Glial Cells during Disease

In a healthy adult brain, glial cell line-derived neurotrophic factor (GDNF) is exclusively expressed by neurons, and, in some instances, it has also been shown to derive from a single neuronal subpopulation. Secreted GDNF acts in a paracrine fashion by forming a complex with the GDNF family receptor α1 (GFRα1), which is mainly expressed by neurons and can act in cis as a membrane-bound factor or in trans as a soluble factor. The GDNF/GFRα1 complex signals through interactions with the “rearranged during transfection” (RET) receptor or via the neural cell adhesion molecule (NCAM) with a lower affinity. GDNF can also signal independently from GFRα1 by interacting with syndecan-3. RET, which is expressed by neurons involved in several pathways (nigro–striatal dopaminergic neurons, motor neurons, enteric neurons, sensory neurons, etc.), could be the main determinant of the specificity of GDNF’s pro-survival effect. In an injured brain, de novo expression of GDNF occurs in glial cells. Neuroinflammation has been reported to induce GDNF expression in activated astrocytes and microglia, infiltrating macrophages, nestin-positive reactive astrocytes, and neuron/glia (NG2) positive microglia-like cells. This disease-related GDNF overexpression can be either beneficial or detrimental depending on the localization in the brain and the level and duration of glial cell activation. Some reports also describe the upregulation of RET and GFRα1 in glial cells, suggesting that GDNF could modulate neuroinflammation.

Rearranged During Transfection Fusions in Non-Small Cell Lung Cancer

Identifying and targeting specific oncogenic drivers has become standard of care in the routine management of patients with lung cancer. Research is ongoing to expand the number of drug targets that can offer clinically meaningful outcomes. Rearranged during transfection (RET) fusions are the latest oncogenic driver alterations that show potential as a drug target. RET fusions occur in 1-2% of non-small cell lung cancer (NSCLC) cases. They are more commonly associated with younger age, female gender, non-smokers and Asian ethnicity. The RET kinase is abnormally activated through fusion with a partner protein such as KIF5B, CCDC6 or NCOA4. This leads to downstream intracellular signalling and enhancement of gene transcription and cell proliferation. The effectiveness of multi-kinase inhibitors in RET positive NSCLC has been explored in early phase and retrospective studies. From these studies, the most effective agents identified include cabozantanib and vandetanib. Overall response rates (ORR) vary from 18-47% across studies. In general, these agents have a manageable toxicity profile, although there are a number of off-target toxicities. Similar to the increased activity in ALK rearranged disease, pemetrexed has demonstrated superior response rates in this patient group and should be considered. Selective RET inhibitors, including LOXO-292 and BLU-667, are progressing in clinical trials. LOXO-292 has demonstrated an impressive ORR of 77% in RET positive solid tumours. It is anticipated this agent will be an effective targeted therapeutic option for patients with RET positive lung cancer.

Incidental Detection of Synchronous Medullary Thyroid Carcinoma with Bilateral Adrenal Pheochromocytoma on Iodine-123 Metaiodobenzylguanidine Scintigraphy, Leading to Diagnosis of Multiple Endocrine Neoplasia 2A

We report a case of a 29-year-old female with the family history of medullary thyroid carcinoma (MTC) presenting with hematuria and tachycardia, who was found to have bilateral adrenal masses on abdominal computed tomography and biochemical testing compatible with pheochromocytoma. Iodine-123 (I-123) metaiodobenzylguanidine (MIBG) scintigraphy for preoperative planning prior to planned adrenalectomy revealed incidental synchronous unifocal MTC, along with expected bilateral adrenal pheochromocytomas. Pathology confirmed these findings, and subsequent genetic testing confirmed a rearranged during transfection proto-oncogene mutation on exon 11, confirming the clinical diagnosis of multiple endocrine neoplasia 2A (MEN 2A). The unexpected incidental finding of synchronous MTC highlights the importance of considering MEN in the differential diagnosis when encountered with newly diagnosed pheochromocytoma and highlights the utility of I-123 MIBG scintigraphy in diagnostic workup of newly diagnosed pheochromocytoma.

Metastatic papillary thyroid carcinoma to the nose: report and review of cutaneous metastases of papillary thyroid cancer

Background:

Metastatic papillary thyroid carcinoma typically appears in local lymph nodes. Skin metastases are rare.

Purpose:

A man with progressive metastatic papillary thyroid carcinoma who developed a cutaneous metastasis on his nose is described. The clinical manifestations of metastatic papillary thyroid carcinoma to skin are reviewed.

Methods:

PubMed was used to search the following terms, separately and in combination: basal, cancer, carcinoma, cell, cutaneous, kinase, inhibitor, metastases, nose, papillary, rearranged during transfection, receptor, RET, thyroid, tyrosine, vandetanib.

Results:

Pathologic changes observed on the biopsy of the man’s nose lesion were similar to those of his original cancer. Genomic evaluation of the tumor revealed an aberration involving the rearranged during transfection (RET) receptor tyrosine kinase. The residual tumor was excised. Treatment with vandetanib, a RET inhibitor was initiated; his metastatic disease has been stable, without symptoms or recurrent cutaneous metastasis, for 2 years following the discovery of his metastatic nose tumor.

Conclusions:

Papillary thyroid carcinoma with skin metastases is rare. Nodules usually appear on the scalp or neck; the thyroidectomy scar is also a common site. Metastatic tumor, albeit infrequently, can present as a nose lesion. The prognosis for patients with cutaneous metastases from papillary thyroid carcinoma is poor. However, with the ability to test the tumor for genomic aberrations, molecular targeted therapies—such as tyrosine kinase inhibitors—may provide extended survival in these individuals.

Neuroprotective effects of electroacupuncture on hypoxic-ischemic encephalopathy in newborn rats are associated with increased expression of GDNF-RET and protein kinase B

OBJECTIVE

To explore the neuroprotective effects of electroacupuncture (EA) on hypoxic-ischemic encephalopathy (HIE) and to further investigate the role of glial cell line-derived neurotrophic factor (GDNF) family receptor member RET (rearranged during transfection) and its key downstream phosphatidylinositol 3 kinase (PI-3K)/protein kinase B (Akt) pathway in the process.

METHODS

A total of 220 seven-day-old SD rats (of either sex, from 22 broods) were randomly divided into two groups, one (30 rats) for sham-surgery group and the other (190 rats) for HIE model group. The HIE model was established using the left common carotid artery ligation method in combination with hypoxic treatment. The successfully established rats were randomly divided into five groups, including control model group, EA group, sham-EA group, antagonist group and antagonist plus electroacupuncture group, with 35 rats in each group. Baihui (GV 20), Dazhui (GV 14), Quchi (LI 11) and Yongquan (KI 1) acupoints were chosen for acupuncture. EA was performed at Baihui and Quchi for 10 min once a day for continuous 1, 3, 7 and 21 days, respectively. The rats were then killed after the operation and injured cerebral cortex was taken for the measurement of neurologic damage by hematoxylin-eosin (HE) staining and the degenerative changes of cortical ultrastructure by transmission electron microscopy. RET mRNA level and Akt protein level were detected by real-time reverse-transcription polymerase chain reaction (RT-PCR) and western blot analysis, respectively.

RESULTS

EA could ameliorate neurologic damage of the first somatic sensory area (S1Tr) and alleviate the degenerative changes of ultrastructure of cortical neurons in rats subjected to HIE. And the longer acupuncture treatment lasted, the better its therapeutic effect would be. This was accompanied by gradually increased expression of GDNF family receptor RET at the mRNA level and its downstream signaling Akt at the protein level in the ischemic cortex.

CONCLUSION

EA has neuroprotective effects on HIE and could be a potential therapeutic strategy for HIE in the neonate. Activation of RET/Akt signaling pathway might be involved in this process.

Recombinant leukemia inhibitory factor suppresses human medullary thyroid carcinoma cell line xenografts in mice

Medullary thyroid carcinoma (MTC) is a neoplasm of the endocrine system, which originates from parafollicular C-cells of the thyroid gland. For MTC therapy, the Food and Drug Administration recently approved vandetanib and cabozantinib, multi-kinase inhibitors targeting RET and other tyrosine kinase receptors of vascular endothelial growth factor, epidermal growth factor, or hepatocyte growth factor. Nevertheless, not all patients with the progressive MTC respond to these drugs, requiring the development of additional therapeutic modalities that have distinct activity. Previously, we reported that expression of activated Ras or Raf in the human MTC cell lines, TT and MZ-CRC-1, can induce growth arrest and RET downregulation via a leukemia inhibitory factor (LIF)-mediated autocrine/paracrine loop. In this study, we aimed to evaluate bacterially-produced recombinant human LIF for its efficacy to suppress human MTC xenografts in mice. Here, we report that, consistent with its effects in vitro, locally or systemically administered recombinant LIF effectively suppressed growth of TT and MZ-CRC-1 xenografts in mice. Further, as predicted from its effects in TT and MZ-CRC-1 cell cultures in vitro, recombinant LIF activated the JAK/STAT pathway and downregulated RET and E2F1 expression in tumors in mice. These results suggest that LIF is a potent cytostatic agent for MTC cells, which regulates unique mechanisms that are not targeted by currently available therapeutic agents.