LIBRETTO-431: Is it time to reconsider randomized phase 3 trials for uncommon oncogenic drivers in non-small-cell lung cancer?

The recently published results of LIBRETTO-4311 pave the way for a new standard of care in the first-line setting for RET-fusion-positive NSCLCs, which raises important clinical questions not only in the therapeutic landscape of advanced NSCLC but also in the drug development process in the era of uncommon molecular subtypes.

Clinical Outcomes of PD-1/PD-L1 Inhibitors Among Patients With Advanced or Metastatic Non-Small Cell Lung Cancer With BRAF, ERBB2/HER2, MET , or RET Alterations: A Systematic Literature Review.

The therapeutic landscape for patients with advanced or metastatic non-small cell lung cancer (NSCLC) is rapidly evolving due to advances in molecular testing and the development of new targeted therapies and immunotherapies. However, the efficacy of programmed death 1 (PD-1)/programmed death ligand 1 (PD-L1) inhibitors in advanced or metastatic patients with NSCLC whose tumors harbor BRAF V600E mutation, HER2/ERBB2 alteration, MET exon 14 skipping mutation, or RET rearrangement is not completely understood. A systematic literature review was performed to summarize evidence from clinical trials and observational studies on objective response rate, progression-free survival, and overall survival in patients whose tumors express these biomarkers and who were treated with PD-1/PD-L1 inhibitors. Searches of Embase, MEDLINE, conference abstracts, and a clinical trial registry identified a total of 12 unique studies: 4 studies included patients with BRAF V600E mutation, 6 studies included patients with HER2/ERBB2 alteration, 7 studies included patients with MET exon 14 skipping mutation, and 5 studies included patients with RET rearrangement. Across studies, there was heterogeneity in treatment and patient characteristics and a lack of reporting on many important predictive and prognostic factors, including treatment regimens, patients' line of therapy, and tumor PD-L1 expression, which may explain the wide variation in objective response rate, progression-free survival, and overall survival across studies. Therefore, additional studies prospectively evaluating clinical outcomes of PD-1/PD-L1 inhibitors among patients with advanced or metastatic NSCLC whose tumors harbor emerging predictive or prognostic biomarkers are needed to determine whether this class of immunotherapy can provide additional survival benefits for these patients.

Pralsetinib-associated pneumonia in RET fusion-positive non-small cell lung cancer.

OBJECTIVE: Oncogenic alternation in RET is one of the important targets of non-small cell lung cancer (NSCLC). Pralsetinib has shown great efficacy in RET fusion-positive NSCLC, but a series of adverse reactions will inevitably occur in the meantime. We aimed to explore the clinical characteristics of patients with pneumonia and recognition it in early stage, so patients could longer benefit from pralsetinib. METHODS: This is a multicenter, retrospective study. RET fusion-positive advanced NSCLC patients who developed pneumonia during pralsetinib treatment from January 2020 to December 2022 were included. Clinical data, time to onset of pneumonia, methods of pneumonia diagnosis, treatment with pneumonia, prognosis of pneumonia, and the effect of pneumonia on the efficacy of pralsetinib. RESULTS: A total of 8 patients with pneumonia were included in the study, most of which were non-smoking female patients and the main fusion gene was KIF5B (87.5%), which was consistent with the general characteristics of RET fusion population. The median occurrence time of pralsetinib-associated pneumonia was 2.15 (range 1.1-6.63) months. All patients were infected by opportunistic pathogens, and the most common pathogen was human herpesviruses and pneumospora yerbii. Fever was always the first symptom, and timely anti-infective treatment including antibiotics, antiviral drugs, and antifungal drugs was effective. Until February 28, 2023, the median follow-up time was 18.7 months, the mean PFS of patients was 17.4 months, and the median PFS was not reached. Fortunately, patients who restarted pralsetinib after infection control continued to benefit. CONCLUSIONS: Opportunistic infection may be a unique adverse effect of pralsetinib. During the treatment of pralsetinib, we should be vigilant about the occurrence of pneumonia and achieve early recognition and timely treatment.

Current landscape and future prospects of RET and ROS1 targets.

RET and ROS1 are becoming key targets for targeted therapy. To show current landscape of ROS1 and RET targets, a patent analysis was performed. The present results indicated that inhibitor structures of ROS1 target demonstrated unique elements compared with inhibitor structures of RET or BRAF targets. Our study was the first time to uncover that a number of inhibitor structures of ROS1 target contained sulfur and boron elements. The inhibitors of RET target could be developed for treatment of various cancers, including lung cancer, thyroid cancer, and other solid tumor, while the inhibitors of ROS1 target are virtually developed for treatment of lung cancer. Our findings provide a new insight for drug discovery of ROS1 and RET target.

Clinical Characteristics and Responses to Immune Checkpoint Inhibitors in RET-Aberrant Digestive Tract Tumours.

BACKGROUND: RET plays an oncogenic role, and its aberrations are potentially actionable. However, they have seldom been reported in tumours other than lung or thyroid cancers. The correlation of RET aberrations with clinical characteristics, co-occurring aberrations, and responses to immune checkpoint inhibitors (ICPi) have not been explored in digestive tract tumours. OBJECTIVES: The aim of the study was to elucidate the clinical characteristics, frequently co-altered genes, and treatment responses in RET-aberrant digestive tract tumours. PATIENTS AND METHODS: We retrospectively evaluated patients with digestive tract cancers for RET-aberrant tumours via FoundationOne CDx tumour-based selected genome sequencing from Jan 2016 to Jan 2021. RESULTS: In a median follow-up time of 51 months, a total of 453 patients were analysed. RET-aberrant tumours accounted for 4.4% in the studied population (n = 20), and 1.1% had an oncogenic fusion (n = 5). APC, KRAS, TP53, MSH6 and STK11 were the differentially co-altered genes (all false discovery rates <0.05). The presence of RET aberrations alone was not a significant prognostic factor. Eleven patients with RET-aberrant tumours received ICPi-based treatment and none achieved an objective response. In contrast, 47 patients with non-aberrant tumours received ICPi treatment and had an objective response rate of 27.7% and a significantly longer treatment duration (6.2 vs 2.8 months, p = 0.0008). CONCLUSIONS: Albeit rarely, RET aberrations can be found in digestive tract tumours. Patients with RET-aberrant tumours have a blunted response to ICPi and a comparable prognosis as compared with RET-wild type tumours. Together, these results provide insights into this rare but potentially actionable target in digestive tract tumours.

Expanded Access Program Pralsetinib in Advanced Non-Small Cell Lung Cancer with Rearranged during Transfection (RET) Gene Rearrangement.

PURPOSE: Rearranged during transfection (RET) gene rearrangement is a well-known driver event in non-small cell lung cancer (NSCLC). Pralsetinib is a selective inhibitor of RET kinase and has shown efficacy in oncogenic RET-altered tumors. This study evaluated the efficacy and safety of expanded access program (EAP) use of pralsetinib in pretreated, advanced NSCLC patients with RET rearrangement. MATERIALS AND METHODS: Patients who received pralsetinib as part of the EAP at Samsung Medical Center were evaluated through a retrospective chart review. The primary endpoint was overall response rate (ORR) per the Response Evaluation Criteria in Solid Tumors (RECIST) ver. 1.1 guidelines. Secondary endpoints were duration of response, progression-free survival (PFS), overall survival (OS), and safety profiles. RESULTS: Between April 2020 and September 2021, 23 of 27 patients were enrolled in the EAP study. Two patients who were not analyzed due to brain metastasis and two patients whose expected survival was within 1 month were excluded from the analysis. After a median follow-up period of 15.6 months (95% confidence interval [CI], 10.0 to 21.2), ORR was 56.5%, the median PFS was 12.1 months (95% CI, 3.3 to 20.9), and the 12-month OS rate was 69.6%. The most frequent treatment-related adverse events (TRAEs) were edema (43.5%) and pneumonitis (39.1%). A total of 8.7% of patients experienced extra-pulmonary tuberculosis. TRAEs with a common grade of three or worse were neutropenia (43.5%) and anemia (34.8%). Dose reduction was required in nine patients (39.1%). CONCLUSION: Pralsetinib presents a clinical benefit when used in patients with RET-rearranged NSCLC, consistent with a pivotal study.

Immune checkpoint inhibitors for RET fusion non-small cell lung cancer: hopes and challenges.

Immune ch eckpoint inhibitors (ICIs) represent a milestone in advanced nonsmall cell lung cancer (NSCLC). Nevertheless, NSCLC with known oncogenic drivers has been overlooked in most studies evaluating anti-programmed death-1/programmed death ligand 1. Rearranged during transfection proto-oncogene (RET) gene fusion was identified in 1-2% of NSCLC patients. More recently, two selective RET inhibitors, selpercatinib and pralsetinib, demonstrated higher efficacy and good tolerability. In contrast, the activity of ICIs in RET fusion NSCLC has not been well characterized. Here, we analyzed the clinical data of ICIs and discussed the suitable time to introduce ICIs in RET fusion NSCLC. Finally, we put forward future strategies to adequately maximize the efficacy of ICIs treatment in patients with RET fusion NSCLC in the upcoming era of combination immunotherapies.

RET Fusion-Positive Non-small Cell Lung Cancer: The Evolving Treatment Landscape.

The objective of this narrative review is to summarize the efficacy and safety of available therapies for rearranged during transfection (RET) fusion-positive non-small cell lung cancer (NSCLC), including in patients with central nervous system (CNS) metastases. Background information is provided on RET rearrangements in NSCLC and the molecular testing options available as well as an overview of clinical guidelines for molecular testing, which recommend broad molecular testing, including for RET rearrangements. The efficacy and safety of potential treatments for RET fusion-positive NSCLC, including multikinase inhibitors, RET-selective inhibitors, pemetrexed-based therapy, and immunotherapies are reviewed from Phase I/II and `real-world' studies, alongside an overview of primary and secondary resistance mechanisms. The RET-selective inhibitors, selpercatinib and pralsetinib, are preferred first-line therapy options for patients with RET fusion-positive metastatic NSCLC and are recommended as subsequent therapy if RET inhibitors have not been used in the first-line setting.

Pralsetinib for RET Fusion-Positive Advanced Non-small-Cell Lung Cancer: An Evidence Review Group Perspective of a NICE Single Technology Appraisal.

The National Institute for Health and Care Excellence (NICE) invited the manufacturer (Roche) of pralsetinib (Gavreto®), as part of the single technology appraisal (STA) process, to submit evidence for the clinical effectiveness and cost effectiveness of pralsetinib for the treatment of adult patients with rearranged during transfection (RET) fusion-positive advanced non-small-cell lung cancer (NSCLC) not previously treated with a RET inhibitor. Kleijnen Systematic Reviews Ltd, in collaboration with University Medical Center Groningen, was commissioned to act as the independent Evidence Review Group (ERG). This paper summarizes the company submission (CS), presents the ERG's critical review of the clinical and cost-effectiveness evidence in the CS, highlights the key methodological considerations, and describes the development of the NICE guidance by the Appraisal Committee. The CS reported data from the ARROW trial. ARROW is a single-arm, multicenter, non-randomized, open-label, multi-cohort study in patients with RET fusion-positive NSCLC and other advanced solid tumors. The CS included both untreated and pre-treated RET fusion-positive NSCLC patients, among other disease types. The comparators in the untreated population were pembrolizumab + pemetrexed + chemotherapy and pembrolizumab monotherapy. The comparators for the pre-treated population were docetaxel monotherapy, docetaxel + nintedanib, and platinum-based chemotherapy ± pemetrexed. As no comparators were included in ARROW, an indirect treatment comparison was conducted to estimate relative effectiveness. The ERG's concerns included the immaturity of data, small sample size, and lack of comparative safety evidence. The ERG considers the clinical evidence presented to be insufficiently robust to inform the economic model. Even when all the ERG preferred assumptions were implemented in the model, uncertainty remained on a number of issues, such as the appropriateness of the hazard ratios and the methods and data used to derive them, long-term efficacy of pralsetinib, and direct evidence for health-related quality of life (HRQoL). NICE did not recommend pralsetinib within its marketing authorization for treating RET fusion-positive advanced non-small-cell lung cancer (NSCLC) in adults who have not had a RET inhibitor before. The uncertainty of the clinical evidence and the estimates of cost effectiveness were too high to be considered a cost-effective use of NHS resources. Therefore, pralsetinib was not recommended for routine use.

Advances in the Diagnosis and Treatment of a Driving Target: RET Rearrangements in non-Small-Cell Lung Cancer (NSCLC) Especially in China.

In the era of precision medicine, with the deepening of the research on malignant tumor driving genes, clinical oncology has fully entered the era of targeted therapy. For non-small-cell lung cancer (NSCLC), the development of targeted drugs targeting driver genes, such as epidermal growth factor receptor (EGFR) and anaplastic lymphoma kinase (ALK), has successfully opened up a new model of targeted therapy. At present, proto-oncogene rearranged during transfection (RET) fusion gene is an important novel oncogenic driving target, and specific receptor tyrosine kinase inhibitors (TKIs) targeting RET fusion have been approved. This article will review the latest research about the molecular characteristics, pathogenesis, detection, and clinical treatment strategies of RET rearrangements especially in China.

Targeting RET alterations in cancer: Recent progress and future directions.

Genomic alterations in the receptor tyrosine kinase RET represent actionable driver events in several cancer types. Activation of the kinase domain by point mutations represents a pathognomonic event in medullary thyroid cancer, while RET fusions are critical driver events in a sizable subset of differentiated thyroid cancer and a smaller percentage of lung cancer. Early trials with multi-kinase inhibitors yielded modest improvement in outcomes for RET-driven cancers. In recent years, highly selective RET inhibitors entered clinical trials and demonstrated remarkable response rates, resulting in accelerated approval for selpercatinib and pralsetinib in 2020. An important mechanism of eventual resistance to RET inhibitors is the emergence of secondary drug resistance mutations, particularly in the solvent front, and several promising compounds are in development to overcome these mutations. Mechanisms of acquired resistance that bypass RET signaling altogether have also been discovered, suggesting that combinatorial drug strategies may be necessary for some patients.

Selpercatinib: A Review in Advanced RET Fusion-Positive NSCLC.

Selpercatinib (Retevmo®/Retsevmo®) is an orally-administered, selective inhibitor of rearranged during transfection (RET) kinase approved for the treatment of advanced RET fusion-positive non-small cell lung cancer (NSCLC). In a pivotal phase 1/2 clinical trial in this population, selpercatinib treatment was associated with robust and durable responses, including intracranial responses, in patients previously treated with platinum-based chemotherapy, as well as in treatment-naïve patients. Selpercatinib had a manageable tolerability profile and an acceptable safety profile; adverse events could generally be managed with dose reductions and only a small proportion of patients discontinued selpercatinib due to treatment-related adverse events. The most common treatment-related adverse events that were grade 3-4 in severity were hypertension, elevated alanine aminotransferase and elevated aspartate aminotransferase. Thus, currently available evidence suggests that selpercatinib is a promising new RET-targeted therapy option for patients with advanced RET fusion-positive NSCLC.

Targeted therapy against the oncogenic driver in tumours carrying such mutations offers the potential for greater anti-tumour efficacy and limited off-target toxicity. Fusion of the rearranged during transfection (RET) gene with another gene is one such driver in a small subset of patients with non-small cell lung cancer (NSCLC). Selpercatinib (Retevmo^®/Retsevmo^®) is a selective RET kinase inhibitor that is taken orally for the treatment of advanced NSCLC with an RET gene fusion. In the pivotal clinical trial in these patients, selpercatinib demonstrated durable responses both in patients previously treated with platinum-based chemotherapy and patients with no prior treatment. Selpercatinib also demonstrated anti-tumour activity against brain metastases associated with NSCLC. Adverse events with selpercatinib were generally manageable with dose reductions and few patients discontinued selpercatinib due to adverse effects. Thus, current data suggest that selpercatinib is a promising new RET-targeted treatment option for advanced RET fusion-positive NSCLC.

Partial response to pralsetinib in an advanced pulmonary sarcomatoid carcinoma patient harboring a KIF5B-RET rearrangement: a case report.

BACKGROUND: Pulmonary sarcomatoid carcinoma (PSC) is a rare and unconventional non-small-cell lung cancer (NSCLC) that appears to be aggressive, with a poor prognosis and response to conventional treatment. Approximately 30% of PSCs have potentially targetable genomic alterations, but few studies have involved RET gene fusions, and corresponding targeted therapies are lacking. CASE PRESENTATION: In this report, we describe a patient with PSC harboring a KIF5B-RET gene fusion who was initially diagnosed with stage IVb lung cancer. Due to the poor performance status, the patient was unable to tolerate any radiotherapy or chemotherapy. Based on the next-generation sequencing (NGS) result of RET gene fusion, the patient was treated with pralsetinib. Two months after the treatment, the patient achieved a partial response. CONCLUSIONS: Our case indicates that RET is one of the main driver oncogenes of PSC and provides useful information for precise RET inhibitor administration in the future. Thus, the use of comprehensive genomic profiling may provide important treatment options for PSC.

Precious Gene: The Application of RET-Altered Inhibitors.

The well-known proto-oncogene rearrangement during transfection (RET), also known as ret proto-oncogene Homo sapiens (human), is a rare gene that is involved in the physiological development of some organ systems and can activate various cancers, such as non-small cell lung cancer, thyroid cancer, and papillary thyroid cancer. In the past few years, cancers with RET alterations have been treated with multikinase inhibitors (MKIs). However, because of off-target effects, these MKIs have developed drug resistance and some unacceptable adverse effects. Therefore, these MKIs are limited in their clinical application. Thus, the novel highly potent and RET-specific inhibitors selpercatinib and pralsetinib have been accelerated for approval by the Food and Drug Administration (FDA), and clinical trials of TPX-0046 and zetletinib are underway. It is well tolerated and a potential therapeutic for RET-altered cancers. Thus, we will focus on current state-of-the-art therapeutics with these novel RET inhibitors and show their efficacy and safety in therapy.

Machine learning driven drug repurposing strategy for identification of potential RET inhibitors against non-small cell lung cancer.

Non-small cell lung cancer (NSCLC) remains the leading cause of mortality and morbidity worldwide accounting about 85% of total lung cancer cases. The receptor REarranged during Transfection (RET) plays an important role by ligand independent activation of kinase domain resulting in carcinogenesis. Presently, the treatment for RET driven NSCLC is limited to multiple kinase inhibitors. This situation necessitates the discovery of novel and potent RET specific inhibitors. Thus, we employed high throughput screening strategy to repurpose FDA approved compounds from DrugBank comprising of 2509 molecules. It is worth noting that the initial screening is accomplished with the aid of in-house machine learning model built using IC50 values corresponding to 2854 compounds obtained from BindingDB repository. A total of 497 compounds (19%) were predicted as actives by our generated model. Subsequent in silico validation process such as molecular docking, MMGBSA and density function theory analysis resulted in identification of two lead compounds named DB09313 and DB00471. The simulation study highlights the potency of DB00471 (Montelukast) as potential RET inhibitor among the investigated compounds. In the end, the half-minimal inhibitory activity of montelukast was also predicted against RET protein expressing LC-2/ad cell lines demonstrated significant anticancer activity. Collective analysis from our study highlights that montelukast could be a promising candidate for the management of RET specific NSCLC.

Outcomes With Local Therapy and Tyrosine Kinase Inhibition in Patients With ALK/ROS1/RET-Rearranged Lung Cancers.

PURPOSE: Local therapy prolongs progression-free survival in patients with oligometastatic non-small-cell lung cancers treated with chemotherapy. We previously reported that local therapy also prolongs survival and time to next therapy in patients on tyrosine kinase inhibitors (TKIs) for EGFR-mutant lung adenocarcinomas. Here, we investigate the role of local therapy in patients progressing on TKIs for ALK/ROS1/RET-rearranged lung adenocarcinomas. MATERIALS AND METHODS: Patients with advanced ALK/ROS/RET-rearranged lung adenocarcinomas who underwent radiation, surgery, or percutaneous thermal ablation from 2012 to 2020 for progression on an ALK/ROS1/RET TKI were included. Progression patterns were identified. Times from local therapy to progression, next therapy, and death were measured. RESULTS: Sixty-one patients with ALK (n = 37), ROS1 (n = 12), and RET (n = 12) fusions were identified. Patients received radiotherapy (92%), surgery (13%), and percutaneous thermal ablation (8%). Local therapy was administered for solitary/oligoprogressive (94%) or polyprogressive (6%) disease. For most patients (85%), local therapy addressed all progressing sites. The median times from any local therapy to subsequent progression and next systemic therapy were 6.8 months (95% CI, 5.1 to 8.1) and 10 months (95% CI, 8.4 to 15.3), respectively. Third or greater local therapy was associated with shorter time to progression and next therapy than first/second local therapies (hazard ratio, 4.97; P < .001 and hazard ratio, 2.48; P < .001). The median overall survival from first local therapy was 34 months (95% CI, 26 to not reached). CONCLUSION: Local therapy for progression on ALK, ROS1, or RET TKIs is associated with clinically meaningful time on continued TKI therapy beyond progression, especially earlier in the course of disease.

RET rearrangements in non-small cell lung cancer: Evolving treatment landscape and future challenges.

The Rearranged during Transfection (RET) oncogene has been extensively investigated in solid malignancies, particularly thyroid cancer and non-small cell lung cancer (NSCLC), and represents an attractive therapeutic target. RET rearrangements occur in 1-2% of lung adenocarcinomas, where they function as potent oncogenic drivers. Importantly, tumors harboring RET fusions are particularly sensitive to RET tyrosine kinase inhibitors. Results of the LIBRETTO-001 and ARROW clinical trials led to the approval of novel potent and selective RET inhibitors, selpercatinib and pralsetinib, able to overcome the limits of previously used multikinase inhibitors. Herein, we review the most relevant evidences about the role of RET signaling in NSCLC. In addition, we interrogated the Project GENIE database to investigate common clinical and molecular features of RET-fusion positive NSCLC. This analysis revealed that RET rearrangements occurred more frequently in younger and light smoker patients and were associated with a lower tumor mutational burden, compared to RET-fusion negative tumors. Moreover, we assessed and described the differences between RET genomic alterations in NSCLC and thyroid cancers. Finally, we summarized how the treatment landscape of RET-rearranged NSCLC has changed in the last few years, which are the available data about the recognized mechanisms of resistance to RET inhibitors and the challenges for future development of novel therapeutic strategies, aiming to improve management of patients with RET-fusion positive NSCLC.

Super-enhancer-controlled positive feedback loop BRD4/ERα-RET-ERα promotes ERα-positive breast cancer.

Estrogen and estrogen receptor alpha (ERα)-induced gene transcription is tightly associated with ERα-positive breast carcinogenesis. ERα-occupied enhancers, particularly super-enhancers, have been suggested to play a vital role in regulating such transcriptional events. However, the landscape of ERα-occupied super-enhancers (ERSEs) as well as key ERα-induced target genes associated with ERSEs remain to be fully characterized. Here, we defined the landscape of ERSEs in ERα-positive breast cancer cell lines, and demonstrated that bromodomain protein BRD4 is a master regulator of the transcriptional activation of ERSEs and cognate ERα target genes. RET, a member of the tyrosine protein kinase family of proteins, was identified to be a key ERα target gene of BRD4-regulated ERSEs, which, in turn, is vital for ERα-induced gene transcriptional activation and malignant phenotypes through activating the RAS/RAF/MEK2/ERK/p90RSK/ERα phosphorylation cascade. Combination therapy with BRD4 and RET inhibitors exhibited additive effects on suppressing ERα-positive breast cancer both in vitro and in vivo, comparable with that of standard endocrine therapy tamoxifen. Furthermore, combination therapy re-sensitized a tamoxifen-resistant ERα-positive breast cancer cell line to tamoxifen treatment. Taken together, our data uncovered the critical role of a super-enhancer-associated positive feedback loop constituting BRD4/ERα-RET-ERα in ERα-positive breast cancer, and suggested that targeting components in this loop would provide a new therapeutic avenue for treating ERα-positive breast cancer in the clinic.

Clinical significance and interrelations of PD-L1 expression, Ki-67 index, and molecular alterations in sporadic medullary thyroid carcinoma from a Chinese population.

Immunotherapy shows prospects in treating advanced medullary thyroid carcinoma although controversial reports are present. Recently, histological grading has been applied to medullary thyroid carcinoma by the Ki-67 index, mitotic figures, and tumor necrosis. However, the interrelation of PD-L1 expression, the Ki-67 index, and major genetic alterations of sporadic medullary thyroid carcinoma has not been fully reported. We examined the expression of PD-L1 (SP142 and 22C3) and the Ki-67 index immunohistologically and detected the major genetic alterations by next-generation sequencing in a cohort of sporadic medullary thyroid carcinomas, studied their survival impact, and discussed their interrelation. We identified that a high Ki-67 index (> 2%) and positive RET M918T mutation were correlated with poor disease-free survival but were not correlated with PD-L1 expression. All PD-L1 positive tumors were RET M918T mutation negative, and PD-L1 expression was positively correlated with HRAS mutation. The Ki-67 index was correlated with neither PD-L1 expression nor major genetic alterations. Our results indicate that immunotherapy targeting PD-L1/PD-1 might be more effective for patients with sporadic medullary thyroid carcinoma harboring HRAS mutations.

[Efficacy and Safety Analysis of Selpercatinib in Patients with RET Fusion-Positive Non-Small Cell Lung Cancer-Results from the Japanese Subset of a Global Phase 1/2 Study].

PURPOSE: Selpercatinib is a highly selective, potent, rearranged during transfection(RET)inhibitor. A global, multicenter, open-label, phase 1/2 study of selpercatinib(LIBRETTO-001, NCT03157128)has been ongoing since 2017. We evaluated the data of Japanese patients with RET fusion-positive non-small cell lung cancer(NSCLC)using 30 March 2020 cut-off data. METHODS: Phase 2 of LIBRETTO-001 started after confirming the safety of the recommended phase 2 dose(160 mg bid, orally, 28-day cycles)in Japanese. The primary endpoint was the independently assessed objective response rate(RECIST v1.1). RESULTS: Japanese NSCLC patients, including 44 patients in cohort 1 who had previously received platinum-based(or other)chemotherapy, programmed cell death-1/programmed death-ligand 1 immunotherapy, or both, and four previously untreated patients in cohort 2, were analyzed. The objective response rate was 55.3%(95% confidence interval: 38.3, 71.4; one confirmed complete response, 20 confirmed partial responses)in 38 evaluable patients in cohort 1 who could be followed for ≥2 post-baseline scans. The only evaluable patient in cohort 2 had no response. The most frequent treatment- emergent adverse events were increased alanine aminotransferase, increased aspartate aminotransferase, and diarrhea. CONCLUSIONS: Selpercatinib appeared to be effective in Japanese patients with RET fusion-positive NSCLC, and the safety profile was not substantially different from published results.