Targeting RET-driven cancers: lessons from evolving preclinical and clinical landscapes

Discovery of an Efficacious RET PROTAC Degrader with Enhanced Antiproliferative Activity against Resistant Cancer Cells Harboring RET Solvent-Front Mutations

Rearranged during transfection (RET) kinase is a validated therapeutic target for various cancers characterized by RET alterations. Although two selective RET inhibitors, selpercatinib and pralsetinib, have been approved by the FDA, acquired resistance through solvent-front mutations has been identified rapidly. Developing proteolysis targeting chimera (PROTAC) targeting RET mutations offers a promising strategy to combat drug resistance. Herein, we describe the design, synthesis, and evaluation of a series of RET PROTAC degraders. The representative compound QZ2135 (20) effectively degraded RET kinase and its resistant mutants, such as V804M and G810C/R. It also exhibited superior antiproliferative activity against Ba/F3 cells stably expressing oncogenic fusions of RET with solvent-front mutants, including G810C/R/S, compared to its parental inhibitor. Notably, QZ2135 demonstrated in vivo antitumor efficacy in a Ba/F3-KIF5B-RET-G810C xenograft mouse model. Together, this study provides a potential alternative strategy for overcoming acquired resistance to RET inhibitors mediated by solvent-front mutations.

Targeting Oncogenic RET Kinase by Simultaneously Inhibiting Kinase Activity and Degrading the Protein

The rearranged-during-transfection (RET) kinase is a validated target for the treatment of RET-altered cancers. Currently approved RET-selective kinase inhibitors, selpercatinib (LOXO-292) and pralsetinib (BLU-667), increase the oncogenic RET protein level upon treatment, which may affect their efficacy. We seek to reduce the oncogenic RET protein level and RET kinase activity simultaneously. Here, we report the development of proteolysis targeting chimera (PROTAC) degraders of oncogenic RET protein. Compound YW-N-7 exhibited dual action of selectively inhibiting and depleting RET protein both in vitro and in vivo. Proteomic analysis indicated that YW-N-7 is highly specific to RET. In cell cultures, reducing RET fusion protein potentiated the activity of LOXO-292. Furthermore, YW-N-7 showed significant activity in inhibiting KIF5B-RET-driven xenograft tumors in animals. This study exemplifies the feasibility of simultaneously inhibiting and degrading oncogenic RET kinase for cancer therapy.

Discovery of a Selective and Orally Bioavailable RET Degrader with Effectiveness in Various Mutations

The rearranged during transfection (RET) mutation such as the G810C mutation has significantly restricted the clinical application of selective RET inhibitors in the treatment of RET-driven cancers. This study designed and evaluated RET proteolysis targeting chimeras (PROTACs) based on selpercatinib (LOXO-292), identifying RD-23 as a potent and selective RET PROTAC. RD-23 effectively inhibited the proliferation of BaF3 cells with various RET mutations, showing IC50 values of 2.4 to 6.5 nM. It selectively induced degradation of the RETG810C mutation via the ubiquitin-proteasome system, with a DC50 (concentration causing 50% of protein degradation) value of 11.7 nM. Additionally, RD-23 exhibited oral bioavailability and superior antitumor effects compared to LOXO-292 in a Ba/F3-KIF5B-RETG810C xenograft mouse model. These results suggested that RD-23 is a promising candidate for treating RET-driven cancers.

Late-line options for patients with metastatic colorectal cancer: a review and evidence-based algorithm

Over the past few years, several novel systemic treatments have emerged for patients with treatment-refractory metastatic colorectal cancer, thus making selection of the most effective later-line therapy a challenge for medical oncologists. Over the past decade, regorafenib and trifluridine-tipiracil were the only available drugs and often provided limited clinical benefit compared to best supportive care. Results from subsequent practice-changing trials opened several novel therapeutic avenues, both for unselected patients (such as trifluridine-tipiracil plus bevacizumab or fruquintinib) and for subgroups defined by the presence of actionable alterations in their tumours (such as HER2-targeted therapies or KRASG12C inhibitors) or with no acquired mechanisms of resistance to the previously received targeted agents in circulating tumour DNA (such as retreatment with anti-EGFR antibodies). In this Review, we provide a comprehensive overview of advances in the field over the past few years and offer a practical perspective on translation of the most relevant results into the daily management of patients with metastatic colorectal cancer using an evidence-based algorithm. Finally, we discuss some of the most appealing ongoing areas of research and highlight approaches with the potential to further expand the therapeutic armamentarium.

Structure-Based Design of 2-Aminopyrazolpyrimidopyridone Derivatives as New Rearranged During Transfection (RET) Kinase Inhibitors

RET (Rearranged during transfection) kinase is a validated target for non-small cell lung cancer (NSCLC). In 2020, two selective RET inhibitors, selpercatinib and pralsetinib were approved by the US FDA. However, high treatment costs and clinically acquired resistance (e.g., G810C/S/R) become the new challenges for RET-based therapies. In this work, we discovered a series of 2-aminopyrazolpyrimidopyridone RET inhibitors to overcome the V804M and G810C resistant mutations. One of the compounds, 8w, exhibited inhibitory potency against the BaF3 cells harboring CCDC6-RETV804M mutation with an IC50 value of 0.715 μM. The compound also dose-dependently suppressed the activation of RET and downstream signals. Another compound, 8s suppressed BaF3 cells harboring CCDC6-RETG810C mutation with an IC50 value of 2.91 μM. However, the poor solubility of these compounds will limit their further development. Therefore, compound 8w and 8s might be promising lead compounds for the development of novel RETV804M and RETG810C inhibitors overcoming the clinically acquired resistance.

Long-term safety of selpercatinib for Rearranged during transfection (RET)-activated advanced solid tumors in LIBRETTO-001: differing patterns of adverse events over time

BACKGROUND

Selpercatinib is a selective RET inhibitor approved for treatment of RET-activated cancers. Adverse events (AEs) are manageable with dose modifications. This post hoc analysis characterized selpercatinib's clinical safety profile after long-term follow-up in the safety population of LIBRETTO-001.

PATIENTS AND METHODS

LIBRETTO-001 is an ongoing phase I/II, single-arm, open-label trial (NCT03157128). Eligible patients were ≥18 years old with diagnosis of advanced/metastatic RET fusion-positive solid tumor, RET-mutant medullary thyroid cancer, or other RET-activated tumors. In phase I, patients received selpercatinib 20 mg QD or 20-240 mg BID; patients in phase II received 160 mg BID. The analyzed population comprised all patients who received ≥1 selpercatinib dose and were followed up until data cutoff (January 13, 2023).

RESULTS

For the 837 patients, median follow-up was 45.4 months (95% CI, 44.5-46.6); median time on treatment was 30.1 months (range 0.1-66.8). Grade ≥3 treatment-emergent AEs (TEAEs) were reported in 76.2% of patients; most common events were hypertension (19.7%), ALT increased (11.8%), and hyponatremia (9.2%). Serious TEAEs were reported in 51.4% of patients. Most frequently reported any-grade AEs at <6 months of treatment were fatigue (36.6%), dry mouth (32.8%), and ALT increased (30.5%); at ≥24 months of treatment, these were edema (63.2%), diarrhea (60.7%), and fatigue (53.0%). Selpercatinib-related TEAEs leading to reduced dosage were reported in 39.3%, those leading to treatment interruption were reported in 47.1%, and those leading to discontinuation were reported in 4.3% of patients.

CONCLUSION

Long-term treatment with selpercatinib is feasible. AEs are manageable with dose modifications, allowing most patients to continue safely on therapy.

Efficacy and Safety of Selective RET Inhibitors in Patients with Advanced Hereditary Medullary Thyroid Carcinoma

Background: Two selective RET inhibitors (RETis) are effective in treating REarranged during Transfection (RET)-altered medullary thyroid carcinoma (MTC), but clinical trials did not distinguish responses between hereditary MTC (hMTC) and sporadic MTC (sMTC) cases. We reviewed our single-center experience using a RETi to treat advanced hMTC. Methods: We conducted a retrospective cohort study of patients with hMTC treated with a selective RETi at a tertiary cancer center. The primary outcome was overall response rate using Response Evaluation Criteria in Solid Tumors (RECIST) v1.1. Secondary end points included overall survival (OS), progression-free survival (PFS), biochemical response rate, and safety. Results: We identified 23 evaluable patients as follows: 15 (65%) multiple endocrine neoplasia (MEN)2A and 8 (35%) MEN2B. Median age at start of RETi was 51 years (range, 15-79). All patients had distant metastases, and 52% (12/23) had received prior systemic therapy (median = 1, range, 0-3). Patients were treated with selpercatinib (n = 13) or pralsetinib (n = 10), 57% (13/23) within a clinical trial. Median duration of RETi was 25 months (range, 3-72) with 11/23 (48%) patients remaining on drug at data cutoff due to an ongoing response. Median duration of follow-up was 49 months (range, 9-72). Best radiographical response was partial response in 18 (78%) and stable disease in 5 (22%) patients. Median OS was 51 months (confidence interval, 40.5-61.3); median PFS was not reached. Most common adverse events (AEs) were increased alanine aminotransferase (ALT) (48%) and aspartate aminotransferase (26%), dry mouth (39%), QT interval prolongation (39%), fatigue (35%), and hypertension (26%). AEs led to dose reductions in eight (35%) patients. No grade 5 treatment-related AEs occurred. While the germline nature of the RET pathogenic variant in hMTC could hypothetically result in increased drug-related toxicity, the incidence of most AEs, other than grade 1-2 ALT elevation and QT interval prolongation, was comparable to published clinical trials. Conclusions: In patients with advanced hMTC, selective RETis appear safe and effective with outcomes similar to clinical trial cohorts, which mostly comprised patients with sMTC. Duration of response and AE profile was similar to sMTC, although longer follow-up and larger patient numbers are needed to confirm this.

Adverse event profiles of selpercatinib: a real-world pharmacovigilance analysis based on FAERS database

BACKGROUND

Selpercatinib, a highly selective tyrosine kinase inhibitor, has emerged as an excellent treatment option for patients with rearranged during transfection-altered cancer. However, there is limited comprehensive safety information available for selpercatinib through large-scale post-marketing monitoring.

METHODS

This study conducted a comprehensive analysis of selpercatinib-related adverse events (AEs) using the FDA Adverse Event Reporting System database. Four disproportionality methods were employed to identify potential AEs associated with selpercatinib. Specifically, this study investigated the differences in AEs of selpercatinib with respect to reporter continent, indication, sex, age, weight, dose, frequency, and onset time.

RESULTS

A total of 464 reports and 1,007 selpercatinib-related AEs were identified. Three new significant AEs were discovered, including dysphagia, pericardial effusion, and hemiparesis. Notably, Asia reported hepatic function abnormal more frequently, especially in patient administered doses exceeding 160 mg. Furthermore, hypersensitivity was reported more frequently by Asia and in individuals weighing less than 50 kg.

CONCLUSIONS

It is paramount to stay vigilant concerning the potential emergence of three newly identified AEs. Significant differences were found in selpercatinib-related AEs concerning reporter continent, sex, weight, dose, frequency, and onset time, which deserved clinical attention. These findings contribute to a broader understanding of the AE profiles of selpercatinib.

Rearranged During Transfection Rearrangement Detection by Fluorescence In Situ Hybridization Compared With Other Techniques in NSCLC

Introduction

RET rearrangements occur in 1% to 2% NSCLCs. Since no clinically validated RET antibody is currently available, fluorescence in situ hybridization (FISH) is often used as a screening tool to identify patients likely to benefit from RET-targeted therapy. In this study, we performed a comprehensive review of publications in which RET-rearrangement testing was performed by FISH and compared the methods and results with our data.

Methods

The findings of an electronic search for publications using RET-FISH in lung cancer were compared with the results obtained at the Grenoble University Hospital where 784 EGFR -, KRAS -, ALK-, and ROS1-negative NSCLCs were tested by RET break-apart FISH and confirmed by RNA-sequencing (RNA-seq).

Results

Out of the 85 publications using RET-FISH analysis, 52 pertained to patients with lung cancer. The most often used positivity threshold was 15%. Six publications compared RET-FISH with at least one other molecular technique on at least eight samples, and the concordance was variable, from 5.9% to 66.7% for FISH-positive cases. Regarding our data, out of the 784 analyzed samples, 32 (4%) were positive by RET-FISH. The concordance between RET-FISH and RNA-seq in RET-FISH positive samples was 69%.

Conclusions

Overall, both existing literature and our data suggest that RET-FISH testing can be used for rapid screening of RET rearrangements in NSCLC. Nevertheless, using an orthogonal technique such as RNA-seq to confirm RET-FISH-positive cases is essential for ensuring that only patients likely to benefit from RET-target therapy receive the treatment.

Invasive aspergillosis complicated in a patient with non-small cell lung cancer harboring RET fusion during treatment with RET-TKIs: a case report and literature review

Pralsetinib and selpercatinib have been approved as specific tyrosine kinase inhibitors (TKIs) for the treatment of patients with non-small cell lung cancer (NSCLC) harboring rearranged during transfection (RET) fusion and mutation. However, adverse events associated with pralsetinib and selpercatinib are not fully understood, especially in the real world. In this case, invasive aspergillosis that appeared concurrent with RET-TKI targeted therapy is proposed to be an additional adverse drug reaction (ADR) that was not mentioned in previous reports. Here, we describe the process of clinical diagnosis and treatment of invasive aspergillosis and attempt to explore its possible pathogenesis in association with RET-TKI targeted therapy, with the aim of providing clinicians a more in-depth understanding of the ADR associated with RET-TKIs, as well as to prevent serious outcomes caused by reduction or discontinuation of antitumor therapy.

Discovery and Synthesis of Heterobifunctional Degraders of Rearranged during Transfection (RET) Kinase

We describe the design, synthesis, and structure-activity relationship (SAR) of heterobifunctional RET ligand-directed degraders (LDDs) derived from three different second-generation RET inhibitors. These LDDs are composed of a target binding motif (TBM) that binds to the RET protein, a linker, and a cereblon binding motif (CBM) as the E3 ligase recognition unit. This led to the identification of a series of pyrazolopyridine-based heterobifunctional LDDs, as exemplified by compound 39. LDD 39 demonstrated high in vitro inhibitory and degradation potency against both RET wild-type and the two representative mutants, V804M and G810R. Importantly, in PK/PD studies, 39 exhibited a differentiated and favorable in vivo profile compared to the corresponding tyrosine kinase inhibitor (TKI), compound 3. Robust and sustained degradation of total-RET (tRET) protein and inhibition of phospho-RET (pRET) signaling were observed in TPC-1 xenograft tumors driven by RET and the RET/G810R mutant following a single dose of LDD 39 at 15 and 75 mg/kg, respectively.

First-in-human, phase 1 dose-escalation and dose-expansion study of a RET inhibitor SY-5007 in patients with advanced RET-altered solid tumors

Oncogenic RET alteration is an important, tissue-agnostic therapeutic target across diverse cancers. We conducted a first-in-human phase 1 study on SY-5007, a potent and selective RET inhibitor, in patients with RET-altered solid tumors. Primary endpoints were safety, maximum tolerated dose (MTD), and recommended phase 2 dose (RP2D). Secondary endpoints included pharmacokinetics and preliminary anti-tumor activity. A total of 122 patients were enrolled (17 in dose-escalation phase and 105 in dose-expansion phase), including 91 with non-small cell lung cancer, 23 with medullary thyroid cancer, 7 with papillary thyroid cancer and 1 with gastric cancer. Treatment-related adverse events (TRAEs) were reported in 96.7% of patients, with the most common grade ≥ 3 TRAEs being hypertension (22.1%), diarrhea (16.4%), hypertriglyceridemia (6.6%), and neutropenia (6.6%). The exposure to SY-5007 was dose proportional. Among the 116 efficacy-evaluable patients, the overall objective response rate (ORR) was 57.8%, with 70.0% in treatment-naïve patients and 51.3% in previously treated patients. The median progression-free survival (PFS) was 21.1 months. Efficacy was observed regardless of tumor types and previous therapies. Biomarker analysis of 61 patients with circulating tumor DNA (ctDNA)-detectable RET alterations showed an ORR of 57.4% and median PFS of 13.8 months. Rapid ctDNA clearance of RET alteration correlated with faster responses and improved outcomes. In relapsed patients, off-target induced resistance was observed in 57.1% (12/21), with no on-target RET alterations identified. In conclusion, SY-5007 was well-tolerated and showed promising efficacy in patients with RET-altered solid tumors. Serial ctDNA monitoring may unveil treatment response and potential resistance mechanisms (NCT05278364).

Fundamentals and recent advances in the evaluation and management of medullary thyroid carcinoma

Medullary thyroid carcinoma (MTC) is a rare primary neuroendocrine thyroid carcinoma that is distinct from other thyroid or neuroendocrine cancers. Most cases of MTC are sporadic, although MTC exhibits a high degree of heritability as part of the multiple endocrine neoplasia syndromes. REarranged during Transfection (RET) mutations are the primary oncogenic drivers and advances in molecular profiling have revealed that MTC is enriched in druggable alterations. Surgery at an early stage is the only chance for cure, but many patients present with or develop metastases. C-cell-specific calcitonin trajectory and structural doubling times are critical biomarkers to inform prognosis, extent of surgery, likelihood of residual disease, and need for additional therapy. Recent advances in the role of active surveillance, regionally directed therapies for localized disease, and systemic therapy with multi-kinase and RET-specific inhibitors for progressive/metastatic disease have significantly improved outcomes for patients with MTC.

Unlocking the future of cancer diagnosis - promises and challenges of ctDNA-based liquid biopsies in non-small cell lung cancer

The advent of liquid biopsies has brought significant changes to the diagnosis and monitoring of non-small cell lung cancer (NSCLC), presenting both promise and challenges. Molecularly targeted drugs, capable of enhancing survival rates, are now available to around a quarter of NSCLC patients. However, to ensure their effectiveness, precision diagnosis is essential. Circulating tumor DNA (ctDNA) analysis as the most advanced liquid biopsy modality to date offers a non-invasive method for tracking genomic changes in NSCLC. The potential of ctDNA is particularly rooted in its ability to furnish comprehensive (epi-)genetic insights into the tumor, thereby aiding personalized treatment strategies. One of the key advantages of ctDNA-based liquid biopsies in NSCLC is their ability to capture tumor heterogeneity. This capability ensures a more precise depiction of the tumor's (epi-)genomic landscape compared to conventional tissue biopsies. Consequently, it facilitates the identification of (epi-)genetic alterations, enabling informed treatment decisions, disease progression monitoring, and early detection of resistance-causing mutations for timely therapeutic interventions. Here we review the current state-of-the-art in ctDNA-based liquid biopsy technologies for NSCLC, exploring their potential to revolutionize clinical practice. Key advancements in ctDNA detection methods, including PCR-based assays, next-generation sequencing (NGS), and digital PCR (dPCR), are discussed, along with their respective strengths and limitations. Additionally, the clinical utility of ctDNA analysis in guiding treatment decisions, monitoring treatment response, detecting minimal residual disease, and identifying emerging resistance mechanisms is examined. Liquid biopsy analysis bears the potential of transforming NSCLC management by enabling non-invasive monitoring of Minimal Residual Disease and providing early indicators for response to targeted treatments including immunotherapy. Furthermore, considerations regarding sample collection, processing, and data interpretation are highlighted as crucial factors influencing the reliability and reproducibility of ctDNA-based assays. Addressing these challenges will be essential for the widespread adoption of ctDNA-based liquid biopsies in routine clinical practice, ultimately paving the way toward personalized medicine and improved outcomes for patients with NSCLC.

A case of selpercatinib treatment for anaplastic thyroid carcinoma resulting in abscess formation

Rearranged during transfection (RET) gene abnormality is a driver gene mutation that causes thyroid cancer, and selpercatinib has been shown to be useful for treating thyroid cancer with RET gene abnormalities. Anaplastic thyroid cancer is a disease with an extremely poor prognosis with no standard treatment established, and there are only one case reports of the efficacy of selpercatinib for RET fusion gene-positive anaplastic thyroid cancer. We herein report our experience treating an old Japanese woman with unresectable anaplastic thyroid cancer with selpercatinib. Surgical resection was initially attempted but was not possible due to adhesion to the common carotid artery. Postoperative genetic testing was positive for the RET fusion gene, and selpercatinib was administered. However, the administration had to be stopped due to the formation of an abscess on day 14 and a pharyngeal fistula on day 17, after which the tumor grew rapidly, and the patient died on day 65. Although selpercatinib has been reported to have a high safety profile with few adverse events, this case suggests that caution should be exercised when treating anaplastic thyroid cancer with invasion to vital organs.

Molecular genetics, therapeutics and RET inhibitor resistance for medullary thyroid carcinoma and future perspectives

Medullary thyroid carcinoma (MTC) is a rare type of thyroid malignancy that accounts for approximately 1-2% of all thyroid cancers (TCs). MTC include hereditary and sporadic cases, the former derived from a germline mutation of rearrangement during transfection (RET) proto-oncogene, whereas somatic RET mutations are frequently present in the latter. Surgery is the standard treatment for early stage MTC, and the 10-year survival rate of early MTC is over 80%. While for metastatic MTC, chemotherapy showing low response rate, and there was a lack of effective systemic therapies in the past. Due to the high risk (ca. 15-20%) of distant metastasis and limited systemic therapies, the 10-year survival rate of patients with advanced MTC was only 10-40% from the time of first metastasis. Over the past decade, targeted therapy for RET has developed rapidly, bringing hopes to patients with advanced and progressive MTC. Two multi-kinase inhibitors (MKIs) including Cabozantinib and Vandetanib have been shown to increase progression-free survival (PFS) for patients with metastatic MTC and have been approved as choices of first-line treatment. However, these MKIs have not prolonged overall survival (OS) and their utility is limited due to high rates of off-target toxicities. Recently, new generation TKIs, including Selpercatinib and Pralsetinib, have demonstrated highly selective efficacy against RET and more favorable side effect profiles, and gained approval as second-line treatment options. Despite the ongoing development of RET inhibitors, the management of advanced and progressive MTC remains challenging, drug resistance remains the main reason for treatment failure, and the mechanisms are still unclear. Besides, new promising therapeutic approaches, such as novel drug combinations and next generation RET inhibitors are under development. Herein, we overview the pathogenesis, molecular genetics and current management approaches of MTC, and focus on the recent advances of RET inhibitors, summarize the current situation and unmet needs of these RET inhibitors in MTC, and provide an overview of novel strategies for optimizing therapeutic effects.

Targeting Solvent-Front Mutations for Kinase Drug Discovery: From Structural Basis to Design Strategies

Solvent-front mutations have emerged as a common mechanism leading to acquired resistance to kinase inhibitors, representing a major challenge in the clinic. Several new-generation kinase inhibitors targeting solvent-front mutations have either been approved or advanced to clinical trials. However, there remains a need to discover effective, new-generation inhibitors. In this Perspective, we systematically summarize the general types of solvent-front mutations across the kinome and describe the development of inhibitors targeting some key solvent-front mutations. Additionally, we highlight the challenges and opportunities for the next generation of kinase inhibitors directed toward overcoming solvent-front mutations.

RET Inhibitors in RET Fusion-Positive Lung Cancers: Past, Present, and Future

While activating RET fusions are identified in various cancers, lung cancer represents the most common RET fusion-positive tumor. The clinical drug development of RET inhibitors in RET fusion-positive lung cancers naturally began after RET fusions were first identified in patient tumor samples in 2011, and thereafter paralleled drug development in RET fusion-positive thyroid cancers. Multikinase inhibitors were initially tested with limited efficacy and substantial toxicity. RET inhibitors were then designed with improved selectivity, central nervous system penetrance, and activity against RET fusions and most RET mutations, including resistance mutations. Owing their success to these rationally designed features, the first-generation selective RET tyrosine kinase inhibitors (TKIs) had higher response rates, more durable disease control, and an improved safety profile compared to the multikinase inhibitors. This led to lung and thyroid cancer, and later tumor-agnostic regulatory approvals. While next-generation RET TKIs were designed to abrogate uncommon on-target (e.g., solvent front mutation) resistance to selpercatinib and pralsetinib, many of these drugs lacked the selectivity of the first-generation TKIs, raising the question of what the future holds for drug development in RET-dependent cancers.

The evolving landscape of tissue-agnostic therapies in precision oncology

Tumor-agnostic therapies represent a paradigm shift in oncology by altering the traditional means of characterizing tumors based on their origin or location. Instead, they zero in on specific genetic anomalies responsible for fueling malignant growth. The watershed moment for tumor-agnostic therapies arrived in 2017, with the US Food and Drug Administration's historic approval of pembrolizumab, an immune checkpoint inhibitor. This milestone marked the marriage of genomics and immunology fields, as an immunotherapeutic agent gained approval based on genomic biomarkers, specifically, microsatellite instability-high or mismatch repair deficiency (dMMR). Subsequently, the approval of NTRK inhibitors, designed to combat NTRK gene fusions prevalent in various tumor types, including pediatric cancers and adult solid tumors, further underscored the potential of tumor-agnostic therapies. The US Food and Drug Administration approvals of targeted therapies (BRAF V600E, RET fusion), immunotherapies (tumor mutational burden ≥10 mutations per megabase, dMMR) and an antibody-drug conjugate (Her2-positive-immunohistochemistry 3+ expression) with pan-cancer efficacy have continued, offering newfound hope to patients grappling with advanced solid tumors that harbor particular biomarkers. In this comprehensive review, the authors delve into the expansive landscape of tissue-agnostic targets and drugs, shedding light on the rationale underpinning this approach, the hurdles it faces, presently approved therapies, voices from the patient advocacy perspective, and the tantalizing prospects on the horizon. This is a welcome advance in oncology that transcends the boundaries of histology and location to provide personalized options.

High success rate of first proficiency testing for RET fusions and RET mutations in lung and thyroid cancer samples by various methods

This study describes the external quality assessment (EQA) scheme for molecular testing of RET alterations in non-small cell lung cancer (NSCLC), medullary thyroid carcinomas (MTC), and non-MTC. The lead panel institute and Quality Assurance Initiative in Pathology (Qualitätssicherungs-Initiative Pathologie [QuIP] GmbH) selected formalin-fixed paraffin-embedded (FFPE) tissue from MTC for RET mutation testing by next-generation sequencing (NGS) methods and FFPE tissue from NSCLC and non-MTC for RET gene fusion testing using either in situ hybridisation (ISH) or NGS methods, forming 3 sub-schemes of the EQA scheme. Tissue material underwent an internal validation phase followed by an external testing phase. The internal validation phase served as a cross-validation step conducted by panel institutes. In the external testing phase, the number of participating institutes in the RET point mutation sub-scheme, RET fusion (ISH) sub-scheme, and RET fusion (NGS) sub-scheme was 32, 24, and 38, respectively. The reported success rates for external testing were 96.0%, 89.5%, and 93.5% for the RET point mutation, the ISH RET fusion, and the NGS RET fusion EQA sub-schemes, respectively. These findings confirm the reliability of the NGS method in detecting RET alterations and align with current screening recommendations. Overall, 31 institutes were certified for RET point mutation testing by NGS methods, 22 institutes were certified for RET fusion testing by ISH, and 36 institutes were certified for RET fusion testing by NGS methods. Results can be employed to inform real-world diagnostic decisions in Germany, Austria, and Switzerland.

Therapeutic advances of targeting receptor tyrosine kinases in cancer

Receptor tyrosine kinases (RTKs), a category of transmembrane receptors, have gained significant clinical attention in oncology due to their central role in cancer pathogenesis. Genetic alterations, including mutations, amplifications, and overexpression of certain RTKs, are critical in creating environments conducive to tumor development. Following their discovery, extensive research has revealed how RTK dysregulation contributes to oncogenesis, with many cancer subtypes showing dependency on aberrant RTK signaling for their proliferation, survival and progression. These findings paved the way for targeted therapies that aim to inhibit crucial biological pathways in cancer. As a result, RTKs have emerged as primary targets in anticancer therapeutic development. Over the past two decades, this has led to the synthesis and clinical validation of numerous small molecule tyrosine kinase inhibitors (TKIs), now effectively utilized in treating various cancer types. In this manuscript we aim to provide a comprehensive understanding of the RTKs in the context of cancer. We explored the various alterations and overexpression of specific receptors across different malignancies, with special attention dedicated to the examination of current RTK inhibitors, highlighting their role as potential targeted therapies. By integrating the latest research findings and clinical evidence, we seek to elucidate the pivotal role of RTKs in cancer biology and the therapeutic efficacy of RTK inhibition with promising treatment outcomes.

REThinking the role of the RET oncogene in breast cancer

The REarranged during Transfection (RET) receptor tyrosine kinase plays a crucial role in the development of various anatomical structures during embryogenesis and it is involved in many physiological cellular processes. This protein is also associated with the initiation of various cancer types, such as thyroid cancer, non-small cell lung cancer, and multiple endocrine neoplasms. In breast cancer, and especially in the estrogen receptor-positive (ER+) subtype, the activity of RET is of notable importance. Indeed, RET seems to be involved in tumor progression, resistance to therapies, and cellular proliferation. Nevertheless, the ways RET alterations could impact the prognosis of breast cancer and its response to treatment remain only partially elucidated. Several inhibitors of RET kinase have been developed thus far, with various degrees of selectivity toward RET inhibition. These molecules showed notable efficacy in the treatment of RET-driven tumors, including some breast cancer cases. Despite these encouraging results, further investigation is needed to fully understand the potential role RET inhibition in breast cancer. This review aims to recapitulate the existing evidence about the role of RET oncogene in breast cancer, from its pathogenic and potentially prognostic role, to the clinical applications of RET inhibitors.

Impact of body surface area on efficacy and safety in patients with EGFR-mutant non-small cell lung cancer treated with osimertinib as a first-line treatment

BACKGROUND

The most recommended treatment for stage IV EGFR-positive lung cancer is osimertinib monotherapy. The dosage of osimertinib is fixed at 80 mg/day regardless of body surface area (BSA), however some patients withdraw or reduce the dosage due to adverse events (AEs).

METHODS

We performed a retrospective cohort study of 98 patients with EGFR mutation-positive non-small cell lung cancer (NSCLC), who received 80 mg osimertinib as the initial treatment. We investigated the impact of BSA on efficacy and safety of osimertinib.

RESULTS

The cut-off value of BSA was estimated using the receiver operating characteristics curve, and was determined to be 1.5 m2. There were 44 patients in the BSA < 1.5 group and 54 patients in the BSA ≥ 1.5 group. There was no significant difference in the incidence of AEs (hematologic toxicity of ≥grade 3 or higher, and non-hematologic toxicity of ≥grade 3) between the two groups. However, the incidence of dose reduction due to AEs was significantly higher in the BSA < 1.5 group compared with the BSA ≥ 1.5 group (16 patients vs 5 patients, p = 0.003). The main reasons were fatigue, anorexia, diarrhea, and liver disfunction. Median progression-free survival (PFS) was not significantly different (16.9 months in the BSA < 1.5 group vs 18.1 months in the BSA ≥ 1.5 group, p = 0.869).

CONCLUSION

Differences in BSA affected the optimal dose of osimertinib. However, the PFS with osimertinib treatment was not affected by BSA. Therefore, when using osimertinib as an initial treatment for patients with EGFR-mutant NSCLC, dose reduction to control AEs should be considered, especially in the BSA<1.5 group.

Target-Driven Tissue-Agnostic Drug Approvals-A New Path of Drug Development

The regulatory approvals of tumor-agnostic therapies have led to the re-evaluation of the drug development process. The conventional models of drug development are histology-based. On the other hand, the tumor-agnostic drug development of a new drug (or combination) focuses on targeting a common genomic biomarker in multiple cancers, regardless of histology. The basket-like clinical trials with multiple cohorts allow clinicians to evaluate pan-cancer efficacy and toxicity. There are currently eight tumor agnostic approvals granted by the Food and Drug Administration (FDA). This includes two immune checkpoint inhibitors, and five targeted therapy agents. Pembrolizumab is an anti-programmed cell death protein-1 (PD-1) antibody that was the first FDA-approved tumor-agnostic treatment for unresectable or metastatic microsatellite instability-high (MSI-H) or deficient mismatch repair (dMMR) solid tumors in 2017. It was later approved for tumor mutational burden-high (TMB-H) solid tumors, although the TMB cut-off used is still debated. Subsequently, in 2021, another anti-PD-1 antibody, dostarlimab, was also approved for dMMR solid tumors in the refractory setting. Patients with fusion-positive cancers are typically difficult to treat due to their rare prevalence and distribution. Gene rearrangements or fusions are present in a variety of tumors. Neurotrophic tyrosine kinase (NTRK) fusions are present in a range of pediatric and adult solid tumors in varying frequency. Larotrectinib and entrectinib were approved for neurotrophic tyrosine kinase (NTRK) fusion-positive cancers. Similarly, selpercatinib was approved for rearranged during transfection (RET) fusion-positive solid tumors. The FDA approved the first combination therapy of dabrafenib, a B-Raf proto-oncogene serine/threonine kinase (BRAF) inhibitor, plus trametinib, a mitogen-activated protein kinase (MEK) inhibitor for patients 6 months or older with unresectable or metastatic tumors (except colorectal cancer) carrying a BRAFV600E mutation. The most recent FDA tumor-agnostic approval is of fam-trastuzumab deruxtecan-nxki (T-Dxd) for HER2-positive solid tumors. It is important to identify and expeditiously develop drugs that have the potential to provide clinical benefit across tumor types.

A Locally Advanced NSCLC Patient Harboring a Rare KIF13A-RET Fusion Benefited from Pralsetinib: A Case Report

The application of adjuvant treatment has significantly enhanced the survival of patients with resectable non-small cell lung cancer (NSCLC) carrying driver gene mutations. However, adjuvant-targeted therapy remains controversial for some NSCLC patients carrying rare gene mutations such as RET, as there is currently a lack of confirmed randomized controlled trials demonstrating efficacy. In this report, we describe the case of a 58-year-old man with stage IIIA NSCLC who underwent complete lobectomy with selective lymph node dissection. Postoperative next-generation sequencing revealed that the patient harbored a rare KIF13A-RET fusion. The patient elected to receive adjuvant treatment with pralsetinib monotherapy and underwent serial circulating tumor DNA (ctDNA) monitoring after surgery. During follow-up, despite experiencing dose reduction and irregular medication adherence, the patient still achieved a satisfactory disease-free survival (DFS) of 27 months. Furthermore, ctDNA predicted tumor recurrence 4 months earlier than imaging techniques. The addition of bevacizumab to the original regimen upon recurrence continued to be beneficial. Pralsetinib demonstrated promising efficacy as adjuvant therapy, while ctDNA analysis offered a valuable tool for early detection of tumor recurrence. By leveraging targeted therapies and innovative monitoring techniques, we aim to improve outcomes and quality of life for NSCLC patients in the future.

A Review of the Molecular Determinants of Therapeutic Response in Non-Small Cell Lung Cancer Brain Metastases

Lung cancer is a leading cause of cancer-related morbidity and mortality worldwide. Metastases in the brain are a common hallmark of advanced stages of the disease, contributing to a dismal prognosis. Lung cancer can be broadly classified as either small cell lung cancer (SCLC) or non-small cell lung cancer (NSCLC). NSCLC represents the most predominant histology subtype of lung cancer, accounting for the majority of lung cancer cases. Recent advances in molecular genetics, coupled with innovations in small molecule drug discovery strategies, have facilitated both the molecular classification and precision targeting of NSCLC based on oncogenic driver mutations. Furthermore, these precision-based strategies have demonstrable efficacy across the blood-brain barrier, leading to positive outcomes in patients with brain metastases. This review provides an overview of the clinical features of lung cancer brain metastases, as well as the molecular mechanisms that drive NSCLC oncogenesis. We also explore how precision medicine-based strategies can be leveraged to improve NSCLC brain metastases.

Developing Dynamic Structure-Based Pharmacophore and ML-Trained QSAR Models for the Discovery of Novel Resistance-Free RET Tyrosine Kinase Inhibitors Through Extensive MD Trajectories and NRI Analysis

Activation of RET tyrosine kinase plays a critical role in the pathogenesis of various cancers, including non-small cell lung cancer, papillary thyroid cancers, multiple endocrine neoplasia type 2A and 2B (MEN2A, MEN2B), and familial medullary thyroid cancer. Gene fusions and point mutations in the RET proto-oncogene result in constitutive activation of RET signaling pathways. Consequently, developing effective inhibitors to target RET is of utmost importance. Small molecules have shown promise as inhibitors by binding to the kinase domain of RET and blocking its enzymatic activity. However, the emergence of resistance due to single amino acid changes poses a significant challenge. In this study, a structure-based dynamic pharmacophore-driven approach using E-pharmacophore modeling from molecular dynamics trajectories is proposed to select low-energy favorable hypotheses, and ML-trained QSAR models to predict pIC50 values of compounds. For this aim, extensive small molecule libraries were screened using developed ligand-based models, and potent compounds that are capable of inhibiting RET activation were proposed.

Efficacy and safety of selpercatinib in treating RET-altered MTC: A single-arm meta-analysis

Background

Selpercatinib is effective in the treatment of RET-altered medullary thyroid carcinoma (MTC). This study aimed to evaluate the efficacy and safety of selpercatinib in the treatment of patients with RET-altered MTC.

Methods

PubMed, Embase, the Cochrane Library, and ClinicalTrials.gov were searched from their inception to April 5, 2024. Outcomes included complete response (CR), partial response (PR), stable disease (SD), objective response rate (ORR), disease control rate (DCR), and adverse events (AEs). We carried out a meta-analysis of these studies and exploratory subgroup analyses. The effect sizes for all pooled results were presented as 95% confidence intervals with upper and lower limits.

Results

The pooled CR, PR, and SD rates for all patients were 10%, 59%, and 26%, respectively. The pooled ORR in all patients was 70%, while the pooled ORR in pre-treated and non-pre-treated groups were 67% and 70%, respectively. The pooled DCR in all patients was 95%, while the pooled DCR in pre-treated and non-pre-treated groups were 96% and 95%, respectively. The most common AEs associated with selpercatinib were hypertension, alanine aminotransferase (ALT) increased and aspartate aminotransferase (AST) increased.

Conclusion

Selpercatinib offers significant benefits to patients with RET-altered MTC with assessable CR, PR, SD, ORR, and grade 3-4 AEs; however, treatment-related AEs should be considered.

Rare Driver Mutations in Advanced, Oncogene-Addicted Non-Small Cell Lung Cancer: A North Italian, Real-World, Registry Experience

The real-world, retrospective, NEROnE registry investigated the impact of next-generation sequencing (NGS) in advanced non-small-cell lung cancer (NSCLC) patients (pts) at three oncology units in the north of Italy between January 2020 and December 2022. We focused on the clinical characterization and outcomes of NSCLC with rare molecular alterations: EGFR exon 20 insertion, non-activating EGFR mutations, BRAF V600E and non-V600, ROS1 and RET rearrangements, MET, ErbB2, and FGFR mutations. Overall, these represented 6.4% (62/970) of the pts analysed with NGS in the daily practice. The most heavily represented rare alterations were ROS1 rearrangement (15 pts-24%) and MET exon 14 skipping mutation (11 pts-18%). No associations were found with the demographic and clinical features. Forty-nine pts received targeted therapies, of which 38.8% were first- and 9.8% were second-line. The remaining pts received chemotherapy and/or immunotherapy. In terms of the clinical outcomes, although not statistically significant, a tendency toward shorter OS was seen when therapies other than specific targeted therapies were used (HR: 1.84, 95% CI: 0.79-4.33, p = 0.158). The pts with co-mutations (19.4%) seemed to receive an advantage from the front-line chemotherapy-based regimen. Finally, an NLR score (a well-known inflammatory index) ≥ 4 seemed to be related to shorter OS among the pts treated with immunotherapy alone or in combination with chemotherapy (HR: 2.83, 95% CI: 1.08-7.40, p = 0.033). Prospective evaluations need to be performed to clarify whether these indexes may help to identify patients with oncogene-addicted NSCLC who could benefit from immunotherapy.

Discovery of 9H-pyrimido[4,5-b]indole derivatives as dual RET/TRKA inhibitors

Aberrant RET kinase signaling is activated in numerous cancers including lung, thyroid, breast, pancreatic, and prostate. Recent approvals of selective RET inhibitors, pralsetinib and selpercatinib, has shifted the focus of RET kinase drug discovery programs towards the development of selective inhibitors. However, selective inhibitors invariably lose efficacy as the selective nature of the inhibitor places Darwinian-like pressure on the tumor to bypass treatment through the selection of novel oncogenic drivers. Further, selective inhibitors are restricted for use in tumors with specific genetic backgrounds that do not encompass diverse patient classes. Here we report the identification of a pyrimido indole RET inhibitor found to also have activity against TRK. This selective dual RET/TRK inhibitor can be utilized in tumors with both RET and TRK genetic backgrounds and can also provide blockade of NTRK-fusions that are selected for from RET inhibitor treatments. Efforts towards developing dual RET/TRK inhibitors can be beneficial in terms of encompassing more diverse patient classes while also achieving blockade against emerging resistance mechanisms.

Next-generation sequencing identified that RET variation associates with lymph node metastasis and the immune microenvironment in thyroid papillary carcinoma

BACKGROUND

To date, although most thyroid carcinoma (THCA) achieves an excellent prognosis, some patients experience a rapid progression episode, even with differentiated THCA. Nodal metastasis is an unfavorable predictor. Exploring the underlying mechanism may bring a deep insight into THCA.

METHODS

A total of 108 THCA from Chinese patients with next-generation sequencing (NGS) were recruited. It was used to explore the gene alteration spectrum of THCA and identify gene alterations related to nodal metastasis in papillary thyroid carcinoma (PTC). The Cancer Genome Atlas THCA cohort was further studied to elucidate the relationship between specific gene alterations and tumor microenvironment. A pathway enrichment analysis was used to explore the underlying mechanism.

RESULTS

Gene alteration was frequent in THCA. BRAF, RET, POLE, ATM, and BRCA1 were the five most common altered genes. RET variation was positively related to nodal metastasis in PTC. RET variation is associated with immune cell infiltration levels, including CD8 naïve, CD4 T and CD8 T cells, etc. Moreover, Step 3 and Step 4 of the cancer immunity cycle (CIC) were activated, whereas Step 6 was suppressed in PTC with RET variation. A pathway enrichment analysis showed that RET variation was associated with several immune-related pathways.

CONCLUSION

RET variation is positively related to nodal metastasis in Chinese PTC, and anti-tumor immune response may play a role in nodal metastasis triggered by RET variation.

Entrectinib as first-line vs. second-line therapy in ROS1 fusion-positive non-small cell lung cancer: a cost-effectiveness analysis

Background

The concept of cost-effectiveness is crucial for the optimal allocation of scarce healthcare resources. However, the cost-effectiveness of entrectinib in ROS1 fusion-positive non-small cell lung cancer (NSCLC) has not been evaluated. We aim to evaluate the cost-effectiveness of entrectinib as a first-line treatment compared to its reservation for second-line therapy or the exclusive use of chemotherapy in ROS1 fusion-positive advanced NSCLC.

Methods

A Markov model was created to assess the clinical outcomes and healthcare costs associated with these three treatment approaches. Cost and utility values were obtained from established literature and cost databases. To test model robustness, probabilistic and univariate sensitivity analyses were conducted.

Results

In the first-line setting, where entrectinib was administered as the initial therapy, it yielded an extra 0.07 quality-adjusted life years (QALYs) at an incremental cost of $73,453, leading to an incremental cost-effectiveness ratio (ICER) of $1,090,594.30 per QALY compared to chemotherapy. Conversely, in the second-line setting, when entrectinib was used as a second-line therapy following chemotherapy, it provided an extra 0.11 QALYs at an incremental cost of $53,480, resulting in an ICER of $494,290.39 per QALY compared to chemotherapy. Furthermore, the analysis revealed that the cost of entrectinib and utility values of progressed disease were the most influential factors for the ICER.

Conclusions

Considering the current pricing of entrectinib, it is not deemed cost-effective as a first-line or second-line therapy for patients with ROS1 fusion-positive advanced NSCLC when compared to chemotherapy. Alternatively, reserving entrectinib exclusively for second-line therapy might strike a balance between healthcare expenditures and patient outcomes.

Prognostic and predictive biomarkers with therapeutic targets in nonsmall-cell lung cancer: A 2023 update on current development, evidence, and recommendation

BACKGROUND

Since the publication of the original work in 2014, significant progress has been made in the characterization of genomic alterations that drive oncogenic addiction of nonsmall cell lung cancer (NSCLC) and how the immune system can leverage non-oncogenic pathways to modulate therapeutic outcomes. This update evaluates and validates the recent and emerging data for prognostic and predictive biomarkers with therapeutic targets in NSCLC.

DATA SOURCES

We performed a literature search from January 2015 to October 2023 using the keywords non-small cell lung cancer, clinical practice guidelines, gene mutations, genomic assay, immune cancer therapy, circulating tumor DNA, predictive and prognostic biomarkers, and targeted therapies.

STUDY SELECTION AND DATA EXTRACTION

We identified, reviewed, and evaluated relevant clinical trials, meta-analyses, seminal articles, and published clinical practice guidelines in the English language.

DATA SYNTHESIS

Regulatory-approved targeted therapies include those somatic gene alterations of EGFR ("classic" mutations, exon 20 insertion, and rare EGFR mutations), ALK, ROS1, BRAF V600, RET, MET, NTRK, HER2, and KRAS G12C. Data for immunotherapy and circulating tumor DNA in next-generation sequencing are considered emerging, whereas the predictive role for PIK3CA gene mutation is insufficient.

CONCLUSIONS

Advances in sequencing and other genomic technologies have led to identifying novel oncogenic drivers, novel resistance mechanisms, and co-occurring mutations that characterize NSCLC, creating further therapeutic opportunities. The benefits associated with immunotherapy in the perioperative setting hold initial promise, with their long-term results awaiting.

RET kinase inhibitors for the treatment of RET-altered thyroid cancers: Current knowledge and future directions

RET gain-of-function mutations are the most common drivers in medullary thyroid carcinoma, while RET fusions are identified in 5-10% of papillary thyroid carcinomas. Thus, RET plays a major role in the tumorigenesis of thyroid neoplasia, making it a valuable therapeutic target. Over a decade ago, multikinase inhibitors (MKIs) were first shown to have variable degrees of anti-RET activity. Despite some clinical efficacy in RET-altered thyroid cancers, significant off-target activity of MKIs led to marked toxicities limiting their use. More recently, two potent, highly selective RET inhibitors, selpercatinib and pralsetinib, were shown to have notable efficacy in RET-altered cancers, associated with more tolerable side effect profiles than those of MKIs. However, these treatments are non-curative, and emerging evidence suggests that patients who progress on therapy acquire mutations conferring drug resistance. Thus, the quest for a more definitive treatment for advanced, RET-altered thyroid cancers continues. This year we celebrate the 30th anniversary of the association of germline mutations of the RET proto-oncogene with the multiple endocrine neoplasia (MEN) type 2 syndromes. In this timely review, we summarize the current state-of-the-art treatment strategies for RET-altered thyroid cancers, their limitations, as well as future therapeutic avenues.

Targeting RET alterations in non-small cell lung cancer

Rearranged during transfection (RET) alterations, which lead to aberrant activation of the RET proto-oncogene, have been identified in various cancers. In non-small cell lung cancer (NSCLC), RET mutations often manifest as RET fusion genes and are observed in 1-2 % of patients with NSCLC. In recent years, selective RET inhibitors such as selpercatinib and pralsetinib, approved by the Food and Drug Administration (FDA) in 2020, have been part of the revolutionary changes in the treatment landscape for non-small cell lung cancer. While first-generation RET inhibitors have become part of the standard of care for RET-fusion positive NSCLC, a new challenge has emerged: acquired resistance to RET inhibitors. RET resistance is a complex phenomenon that can manifest as either on-target or off-target resistance. Numerous studies have been conducted to identify the mechanisms behind this resistance. This review provides an overview of the biology of RET in NSCLC, methods of RET testing, and a comprehensive analysis of the clinical outcomes associated with multikinase and selective RET inhibitors for NSCLC. Additionally, we will explore future perspectives for RET fusion-positive NSCLC, including ongoing trials and the challenges involved in overcoming resistance to RET inhibitors.

Tissue-Agnostic Cancer Therapy Approvals

Tumor-agnostic, or histology-agnostic, cancer therapy marks a groundbreaking evolution in the realm of precision oncology. In stark contrast to conventional cancer treatments that categorize malignancies based on their tissue of origin (eg, breast, lung, renal cell, etc), tumor-agnostic therapies transcend histologic boundaries, honing in on the genetic and molecular attributes of tumors, regardless of their location. This article offers a comprehensive review of the current landscape of tissue-agnostic cancer therapies and provides clinical insights to empower surgical oncologists with a deeper understanding of these innovative therapeutic approaches.

Deterministic reprogramming and signaling activation following targeted therapy in non-small cell lung cancer driven by mutations or oncogenic fusions

INTRODUCTION

Targeted therapy is used to treat lung adenocarcinoma caused by epidermal growth factor receptor (EGFR) mutations in the tyrosine kinase domain and rare subtypes (<5%) of non-small cell lung cancer. These subtypes include fusion oncoproteins like anaplastic lymphoma kinase (ALK), ROS1, rearranged during transfection (RET), and other receptor tyrosine kinases (RTKs). The use of diverse selective oral inhibitors, including those targeting rat sarcoma viral oncogene homolog (KRAS) mutations, has significantly improved clinical responses, extending progression-free and overall survival.

AREAS COVERED

Resistance remains a critical issue in lung adenocarcinoma, notably in EGFR mutant, echinoderm microtubule associated protein-like 4 (EML4)-ALK fusion, and KRAS mutant tumors, often associated with epithelial-to-mesenchymal transition (EMT).

EXPERT OPINION

Despite advancements in next generation EGFR inhibitors and EML4-ALK therapies with enhanced brain penetrance and identifying resistance mutations, overcoming resistance has not been abated. Various strategies are being explored to overcome this issue to achieve prolonged cancer remission and delay resistance. Targeting yes-associated protein (YAP) and the mechanisms associated with YAP activation through Hippo-dependent or independent pathways, is desirable. Additionally, the exploration of liquid-liquid phase separation in fusion oncoproteins forming condensates in the cytoplasm for oncogenic signaling is a promising field for the development of new treatments.

Prognostic and predictive biomarkers in non-small cell lung carcinoma

Lung cancer is the most common cause of cancer-related deaths globally, with the highest mortality rates among both men and women. Most lung cancers are diagnosed at late stages, necessitating systemic therapy. Modern clinical management of lung cancer relies heavily upon application of biomarkers, which guide the selection of systemic treatment. Here, we provide an overview of currently approved and emerging biomarkers of non-small cell lung cancer (NSCLC), including EGFR, ALK, ROS1, RET, NTRK1-3, KRAS, BRAF, MET, ERBB2/HER2, NRG1, PD-L1, TROP2, and CEACAM5. For practical purposes, we divide these biomarkers into genomic and protein markers, based on the tested substrate. We review the biology and epidemiology of the genomic and proteomic biomarkers, discuss optimal diagnostic assays for their detection, and highlight their contribution to the contemporary clinical management of NSCLC.

Molecular classification and tumor microenvironment characteristics in pheochromocytomas

Pheochromocytomas (PCCs) are rare neuroendocrine tumors that originate from chromaffin cells in the adrenal gland. However, the cellular molecular characteristics and immune microenvironment of PCCs are incompletely understood. Here, we performed single-cell RNA sequencing (scRNA-seq) on 16 tissues from 4 sporadic unclassified PCC patients and 1 hereditary PCC patient with Von Hippel-Lindau (VHL) syndrome. We found that intra-tumoral heterogeneity was less extensive than the inter-individual heterogeneity of PCCs. Further, the unclassified PCC patients were divided into two types, metabolism-type (marked by NDUFA4L2 and COX4I2) and kinase-type (marked by RET and PNMT), validated by immunohistochemical staining. Trajectory analysis of tumor evolution revealed that metabolism-type PCC cells display phenotype of consistently active metabolism and increased metastasis potential, while kinase-type PCC cells showed decreased epinephrine synthesis and neuron-like phenotypes. Cell-cell communication analysis showed activation of the annexin pathway and a strong inflammation reaction in metabolism-type PCCs and activation of FGF signaling in the kinase-type PCC. Although multispectral immunofluorescence staining showed a lack of CD8+ T cell infiltration in both metabolism-type and kinase-type PCCs, only the kinase-type PCC exhibited downregulation of HLA-I molecules that possibly regulated by RET, suggesting the potential of combined therapy with kinase inhibitors and immunotherapy for kinase-type PCCs; in contrast, the application of immunotherapy to metabolism-type PCCs (with antigen presentation ability) is likely unsuitable. Our study presents a single-cell transcriptomics-based molecular classification and microenvironment characterization of PCCs, providing clues for potential therapeutic strategies to treat PCCs.

Case report: First evidence of impressive efficacy of modulated dose selpercatinib in a young Caucasian with ANK3-RET fusion-positive NSCLC

Over the past decade, molecular characterization has led to change the management of advanced non-small cell lung cancer (NSCLC) harboring driver mutations. Rearranged during transfection (RET) gene fusions, occurring in 1% to 2% of NSCLC, have emerged as an oncogenic druggable target. Systemic targeted therapies with highly selective RET inhibitors (RETi), selpercatinib and pralsetinib, represent a recent clinical breakthrough. While the development of RETi has improved survival, with their increasing use, it is crucial to be aware of the risks of rare but serious adverse events (AEs). A particular challenge for clinicians in applying targeted therapies is not only diagnosing but also interpreting rare mutations. Herein, we report a case of a 43-year-old Caucasian advanced NSCLC patient diagnosed with a rare RET gene fusion, ANK3::RET, identified with Next Generation Sequencing (NGS). Selpercatinib has been initiated at the recommended initial dose after one incomplete chemotherapy cycle due to a severe infusion reaction, but it subsequently required a dose adjustment following grade 3 (G3) AEs. During treatment, we used a particular selpercatinib dosage (160 mg in the morning and 80 mg in the evening) with good tolerance and without compromising effectiveness. Our finding broadens the range of RET fusion types in not-Asian NSCLC. To the best of our knowledge, our case demonstrates, for the first time, a clinical and radiological response to frontline highly selective RETi selpercatinib, expanding the spectrum of potential oncogenic RET fusion partners in newly diagnosed NSCLC patients. Furthermore, to our knowledge, this is the first case describing a RET fusion-positive (RET+) NSCLC patient treated with a modified selpercatinib dosage outside the drug data sheet and demonstrating a safe and effective use.

Molecular pathology in diagnosis and prognostication of head and neck tumors

Classification of head and neck tumors has evolved in recent decades including a widespread application of molecular testing in tumors of the salivary glands, sinonasal tract, oropharynx, nasopharynx, and soft tissue. Availability of new molecular techniques allowed for the definition of multiple novel tumor types unique to head and neck sites. Moreover, the expanding spectrum of immunohistochemical markers facilitates a rapid identification of diagnostic molecular abnormalities. As such, it is currently possible for head and neck pathologists to benefit from a molecularly defined classifications, while making diagnoses that are still based largely on histopathology and immunohistochemistry. This review highlights some principal molecular alterations in head and neck neoplasms presently available to assist pathologists in the practice of diagnosis, prognostication and prediction of response to treatment.

Recent Advances in Pyrimidine-Based Drugs

Pyrimidines have become an increasingly important core structure in many drug molecules over the past 60 years. This article surveys recent areas in which pyrimidines have had a major impact in drug discovery therapeutics, including anti-infectives, anticancer, immunology, immuno-oncology, neurological disorders, chronic pain, and diabetes mellitus. The article presents the synthesis of the medicinal agents and highlights the role of the biological target with respect to the disease model. Additionally, the biological potency, ADME properties and pharmacokinetics/pharmacodynamics (if available) are discussed. This survey attempts to demonstrate the versatility of pyrimidine-based drugs, not only for their potency and affinity but also for the improved medicinal chemistry properties of pyrimidine as a bioisostere for phenyl and other aromatic π systems. It is hoped that this article will provide insight to researchers considering the pyrimidine scaffold as a chemotype in future drug candidates in order to counteract medical conditions previously deemed untreatable.

Efficacy of first-line treatment options beyond RET-TKIs in advanced RET-rearranged non-small cell lung cancer: A multi-center real-world study

BACKGROUND

Although RET-tyrosine kinase inhibitors (RET-TKIs) are the preferred first-line therapy for advanced RET-arranged NSCLC, most patients cannot afford them. In this population, bevacizumab, immunotherapy, and chemotherapy are the most commonly used regimens. However, the optimal scheme beyond RET-TKIs has not been defined in the first-line setting.

METHODS

This retrospective study included 86 stage IV NSCLC patients harboring RET rearrangement from six cancer centers between May 2017 and October 2022. RET-TKIs, chemotherapy, or one of the combination therapies (including immune checkpoint inhibitor (ICI) combined with chemotherapy (I + C), bevacizumab combined with chemotherapy (B + C), ICI and bevacizumab combined with chemotherapy (I + B + C)), were used as the first-line therapeutics. The clinical outcomes and safety were evaluated.

RESULTS

Fourteen of the 86 patients received RET-TKIs, 57 received combination therapies, and 15 received chemotherapy alone. Their medium PFS (mPFS) were 16.92 months (95% CI: 5.9-27.9 months), 8.7 months (95% CI: 6.5-11.0 months), and 5.55 months (95% CI: 2.4-8.7 months) respectively. Among all the combination schemes, B + C (p = 0.007) or I + B + C (p = 0.025) gave beneficial PFS compared with chemotherapy, while I + C treatment (p = 0.169) generated comparable PFS with chemotherapy. In addition, I + B + C treatment had a numerically longer mPFS (12.21 months) compared with B + C (8.74 months) or I + C (7.89 months) schemes. In terms of safety, I + B + C treatment led to the highest frequency of hematological toxicity (50%) and vomiting (75%), but no ≥G3 adverse effect was observed.

CONCLUSIONS

I + B + C might be a preferred option beyond RET-TKIs in the first-line therapy of RET-arranged NSCLC. Combination with Bevacizumab rather than with ICIs offered favorable survival compared with chemotherapy alone.

Integrated budget impact model to estimate the impact of introducing selpercatinib as a tumor-agnostic treatment option for patients with RET-altered solid tumors in the US

OBJECTIVE

To estimate the potential budget impact on US third party payers (commercial or Medicare) associated with addition of selpercatinib as a tumor-agnostic treatment for patients with Rearranged during Transfection (RET)-altered solid tumors.

METHODS

An integrated budget impact model (iBIM) with 3-year (Y) time horizon was developed for 19 RET-altered tumors. It is referred to as an integrated model because it is a single model that integrated results across multiple tumor types (as opposed to tumor-specific models developed traditionally). The model estimated eligible patient populations and included tumor-specific comparator treatments for each tumor type. Estimated annual total costs (2022USD, $) included costs of drug, administration, supportive care, and toxicity. For a one-million-member plan, the number of patients with RET-altered tumors eligible for treatment, incremental total costs, and incremental per-member per-month (PMPM) costs associated with introduction of selpercatinib treatment were estimated. Uncertainty associated with model parameters was assessed using various sensitivity analyses.

RESULTS

Commercial perspective estimated 11.68 patients/million with RET-altered tumors as treatment-eligible annually, of which 7.59 (Y1), 8.17 (Y2), and 8.76 (Y3) patients would be selpercatinib-treated (based on forecasted market share). The associated incremental total and PMPM costs (commercial) were estimated to be: $873,099 and $0.073 (Y1), $2,160,525 and $0.180 (Y2), and $2,561,281 and $0.213 (Y3), respectively. The Medicare perspective estimated 55.82 patients/million with RET-altered tumors as treatment-eligible annually, of which 36.29 (Y1), 39.08 (Y2), and 41.87 (Y3) patients would be selpercatinib-treated. The associated incremental total and PMPM costs (Medicare) were estimated to be: $4,447,832 and $0.371 (Y1), $11,076,422 and $0.923 (Y2), and $12,637,458 and $1.053 (Y3), respectively. One-way sensitivity analyses across both perspectives identified drug costs, selpercatinib market share, incidence of RET, and treatment duration as significant drivers of incremental costs.

CONCLUSIONS

Three-year incremental PMPM cost estimates suggest a modest impact on payer-budgets associated with introduction of tumor-agnostic selpercatinib treatment.

A narrative review of the evolving landscape of the management of metastatic gastric cancer: the role of targeted therapies

Background and Objective

Gastric cancer is the fifth most common cancer worldwide and the fourth leading cause of cancer-related death. Unfortunately, patients often present with advanced disease at diagnosis, which is directly related to its high mortality. Numerous trials, as early as the 1980's, have shown that cytotoxic chemotherapy improves survival. This review will focus on targeted therapies and immunotherapies which have emerged as treatment options for metastatic gastric cancer, often used in conjunction with cytotoxic chemotherapy. Here we will review the relevant clinical trials of targeted therapies and immunotherapies in the treatment of metastatic gastric cancer.

Methods

We performed an extensive review of articles in the PubMed database pertaining to targeted therapies and immunotherapies in the treatment of metastatic gastric cancer. Additionally, updated guidelines from the National Comprehensive Cancer Network (NCCN) and European Society for Medical Oncology (ESMO) were reviewed.

Key Content and Findings

Cytotoxic chemotherapy remains the backbone of treatment of metastatic gastric cancer, but the development of targeted therapies and immunotherapy have revolutionized its treatment with improved survival and outcomes. Therapies have been developed which target human epidermal growth factor receptor 2 (HER2), vascular endothelial growth factor receptor-2 (VEGFR-2), and tyrosine kinase pathways. Novel targeted therapies are currently being investigated with promising results thus far. Immunotherapy, specifically immune checkpoint inhibitors (ICIs), has proven to be a significant advancement in the treatment of gastric cancer.

Conclusions

Targeted therapies and immunotherapies have improved survival and outcomes in metastatic gastric cancer, however more research is needed to make even greater strides.

Selective RET Inhibitors (SRIs) in Cancer: A Journey from Multi-Kinase Inhibitors to the Next Generation of SRIs

RET is a receptor tyrosine kinase that plays an important role in the development of neurons and kidneys. The gene encoding the rearranged-during-transfection (RET) receptor tyrosine kinase was first discovered in the 1980s. Activating RET mutations and rearrangements have since been identified as actionable drivers of oncogenesis in numerous cancer types and are most prevalent in thyroid and non-small-cell lung cancer. Following the modest success of repurposed RET-active multikinase inhibitors, the first selective RET inhibitors (SRIs), selpercatinib and pralsetinib, received regulatory approval in 2020. Now, thousands of patients with RET-altered cancers have benefited from first-generation SRIs, with impressive deep and durable responses. However, following prolonged treatment with these SRIs, a number of acquired on-target resistance mutations have been identified together with other non-RET-dependent resistance mechanisms. Today, the focus is on how we can further evolve and improve the treatment of RET-altered tumors with next-generation SRIs, and a number of candidate drugs are in development. The ideal next-generation SRIs will be active against on-target acquired resistance alterations, including those that emerge in the CNS, and will have improved safety and tolerability relative to first-generation SRIs. In this review, we will provide an update on these candidates and their potential to meet the unmet clinical need for patients who progress on first-generation SRIs.

Strategies for mitigating adverse events related to selective RET inhibitors in patients with RET-altered cancers

The US Food and Drug Administration (FDA) approval of the selective RET inhibitors selpercatinib and pralsetinib has led to a paradigm change in the treatment of RET-altered lung and thyroid cancers through a higher response rate and a more tolerable safety and toxicity profile than multi-kinase inhibitors. Recently, selpercatinib has received a tissue-agnostic FDA approval for all RET-fusion-positive cancers, and pralsetinib has shown pan-cancer activity as well. Given the anticipated increase in the use of both drugs across multiple tumor types, it is crucial to recognize the possible side effects and approaches for their optimal management in order to maximize the clinical benefit for treated patients. In this review, we underscore potential toxicities associated with selective RET inhibitors and discuss strategies to mitigate them.

Design and synthesis of certain 7-Aryl-2-Methyl-3-Substituted Pyrazolo{1,5-a}Pyrimidines as multikinase inhibitors

Four new series 7a-e, 8a-e, 9a-e, and 10a-e of 7-aryl-3-substituted pyrazolo[1,5-a]pyrimidines were synthesized and tested for their RTK and STK inhibitory activity. Compound 7d demonstrated potent enzymatic inhibitory activity against TrkA and ALK2 with IC50 0.087and 0.105 μM, respectively, and potent antiproliferative activity against KM12 and EKVX cell lines with IC50 0.82 and 4.13 μM, respectively. Compound 10e showed good enzyme inhibitory activity against TrkA, ALK2, c-KIT, EGFR, PIM1, CK2α, CHK1, and CDK2 in submicromolar values. Additionally 10e revealed antiproliferative activity against MCF7, HCT116 and EKVX with IC50 3.36, 1.40 and 3.49 μM, respectively; with good safety profile. Moreover, 10e showed cell cycle arrest at the G1/S phase and G1 phase in MCF7 and HCT116 cells with good apoptotic effect. Molecular docking studies were fulfilled for compound 10e and illustrated good interaction with the hot spots of the active site of the tested enzymes.

Receptor tyrosine kinases: biological functions and anticancer targeted therapy

Receptor tyrosine kinases (RTKs) are a class of protein kinases that play crucial roles in various cellular processes, including cell migration, morphological differentiation, cell growth, and angiogenesis. In humans, 58 RTKs have been identified and categorized into 20 distinct families based on the composition of their extracellular regions. RTKs are primarily activated by specific ligands that bind to their extracellular region. They not only regulate tumor transformation, proliferation, metastasis, drug resistance, and angiogenesis, but also initiate and maintain the self-renewal and cloning ability of cancer stem cells. Accurate diagnosis and grading of tumors with dysregulated RTKs are essential in clinical practice. There is a growing body of evidence supporting the benefits of RTKs-targeted therapies for cancer patients, and researchers are actively exploring new targets and developing targeted agents. However, further optimization of RTK inhibitors is necessary to effectively target the diverse RTK alterations observed in human cancers. This review provides insights into the classification, structure, activation mechanisms, and expression of RTKs in tumors. It also highlights the research advances in RTKs targeted anticancer therapy and emphasizes their significance in optimizing cancer diagnosis and treatment strategies.

Inhibition of a lower potency target drives the anticancer activity of a clinical p38 inhibitor

The small-molecule drug ralimetinib was developed as an inhibitor of the p38α mitogen-activated protein kinase, and it has advanced to phase 2 clinical trials in oncology. Here, we demonstrate that ralimetinib resembles EGFR-targeting drugs in pharmacogenomic profiling experiments and that ralimetinib inhibits EGFR kinase activity in vitro and in cellulo. While ralimetinib sensitivity is unaffected by deletion of the genes encoding p38α and p38β, its effects are blocked by expression of the EGFR-T790M gatekeeper mutation. Finally, we solved the cocrystal structure of ralimetinib bound to EGFR, providing further evidence that this drug functions as an ATP-competitive EGFR inhibitor. We conclude that, though ralimetinib is >30-fold less potent against EGFR compared to p38α, its ability to inhibit EGFR drives its primary anticancer effects. Our results call into question the value of p38α as an anticancer target, and we describe a multi-modal approach that can be used to uncover a drug's mechanism-of-action.