MEK Inhibitor Research Articles

Efficacy and toxicity of BRAF targeted therapy in elderly patients with melanoma.

e23270 Background: Melanoma is the most lethal form of skin cancer which have seen drastic improvement in patient survival over the last decade. BRAF is the most common driver mutation in melanoma, seen in ≈50% of all patients (≈30% of patients > 65). The use of BRAF & MEK inhibitors yields high response rates, though it is limited by toxicity and development of acquired resistance. Acknowledging these limitations, we aimed at assessing the efficacy and toxicity of these agents in melanoma patients > 65. Methods: We identified electronic medical records of all melanoma patients > 65 that were treated with BRAF & MEK inhibitors at our institution over the years 2017-2023. Data was retrospectively collected including demographics, disease characteristics, treatment given, response patterns and toxicity. Results: 106 patients were identified. The median age was 71 (65-89), 55% were males. The median follow up was 28.9 months. 32 (30%) patients were treated at first line, 58 (55%) at second line and 16 (15%) at third line. 88 (83%) evaluable patients received treatment for unresectable/metastatic disease of which 84% had an objective response (60% partial response, 24% complete response). Response rate (RR) was 82%, 85% and 87% for first, second and third line respectively. RR was 86% for patients with an increased serum lactate dehydrogenase. 33% of patients had active central nervous system (CNS) metastases at treatment initiation, for whom the systemic RR was 80% and the CNS RR was 39%. The median progression free survival (PFS) was 7.9 months, with a PFS of 6, 8.3 and 13.4 months for first, second and third line respectively. The median PFS was 5.7 months for patients with active CNS disease. The median overall survival (OS) from treatment initiation was 15.7 months (12.5, 14.5, 31.9 for first, second & third line respectively). The median OS for patients with CNS disease was 9.8 months. 16 patients were treated in the adjuvant setting, of which 6 (37%) finished treatment as planned, 3 stopped due to disease progression (19%) and 6 stopped due to toxicity (37%). 88% of patients experienced adverse events (AEs) of any grade, with 27% having grade 3-4 toxicity. There were no grade 5 toxicities reported. 36% of patients experienced one AE, while 52% experienced two or more. 21% of patients stopped treatment due to toxicity, 28% needed a dose reduction and 20% changed to different BRAF/MEK inhibitors. 10% of patients needed systemic corticosteroids to treat AEs. The most common toxicities seen were fever (30%), fatigue (30%), skin rash (22%), elevated liver function tests (20%), arthralgia/myalgia (15%), nausea (14%) and diarrhea (11%). 7% had decrease in cardiac ejection fraction with one grade 3 leading to treatment discontinuation. Conclusions: Treatment with BRAF & MEK inhibitors is challenging in older patients, with a high prevalence of toxicity leading to treatment modifications and discontinuation. Efficacy seems to be the same as in the general population.

MEK inhibitor PD0325901 upregulates CD34 expression in endothelial cells via inhibition of ERK phosphorylation

IntroductionCD34-positive endothelial progenitor cells (EPCs) promote angiogenesis and are a promising tool for regenerative cell therapy of ischemic diseases. However, the number and quality of CD34-positive cells decrease owing to various external and internal factors; thus, an efficient method is needed to establish CD34-positive EPCs. The generation of functional cells by reprogramming, that is, manipulating cell fate via gene transfer and/or treatment with chemical compounds, has recently been reported. Therefore, we aimed to generate CD34-positive cells by the reprogramming of endothelial cells (ECs). MethodsBased on previous reports, seven candidate chemical compounds were selected to reprogram human umbilical vein ECs (HUVECs) to CD34-positive cells. Following stimulation with the chemical compounds, the expression of CD34 was evaluated using quantitative PCR, flow cytometry, and immunocytochemistry. ResultsHUVECs treated with the compounds exhibited increased CD34 expression. We cultured cells in alternate media lacking one of the seven compounds and found no CD34 expression in cells treated with PD0325901-free media, suggesting that PD0325901—a MEK inhibitor—mainly contributed to the increase in CD34 expression. We found that 98% of cells were CD34-positive after PD0325901 treatment alone for 7 d. Western blotting revealed that the phosphorylation of ERK was suppressed in PD0325901-treated cells. No upregulation of CD34 was observed in fibroblast cell lines, even after PD0325901 treatment. These results suggested that PD0325901 induces CD34-positive cells by inhibiting ERK phosphorylation in ECs. ConclusionsCD34 expression was strongly induced in ECs by treatment with the MEK inhibitor PD0325901 in vitro. Our study provides a useful reference for the establishment of CD34-positive EPCs and will contribute to the development of regenerative therapies, especially for ischemic diseases.

Alliance EAY191-A6: FOLFOX in combination with binimetinib as second-line therapy for patients with advanced biliary tract cancers (BTCs) with MAPK pathway alterations: A ComboMATCH treatment trial.

TPS4196 Background: Advanced BTC patients have poor prognosis. Up to 40% of BTCs have KRAS mutations and are associated with worse overall survival (OS). With a median OS of 7.7 months in KRAS wild-type compared to 1.7 months in KRAS mutated disease, these alterations are independent poor prognostic factors in BTC. Gemcitabine and cisplatin (GC) with or without immunotherapy are often used as 1st-line therapies. However, there is a lack of data on best 2nd-line regimens. mFOLFOX6 (5-fluorouracil [5-FU], leucovorin [LV], oxaliplatin) or liposomal irinotecan+5-FU+LV are options when no biomarkers are found (e.g., MSI-H, BRAFV600E, FGFR-fusions, IDH1-mutation, HER2-overexpression). Prior studies do not demonstrate benefit with MEK inhibitors (MEKi), but none of the studies had biomarker selection. Pre-clinical studies in BTC cell lines suggest synergy between MEKi and 5-FU. Thymidylate synthase (TS )levels induced by 5-FU are downregulated by addition of binimetinib. Early clinical studies show safety and tolerance of this combination. In this study, we will evaluate if the combination of mFOLFOX6+binimetinib improves OS for patients with BTC and MAPK mutations compared to mFOLFOX6 alone in 2nd-line therapy. Methods: EAY191-A6 is a treatment study arm of the NCI ComboMATCH master registration trial EAY191. The A6 trial has a randomized phase II design, enrolling a maximum of 66 patients. Patients with any MAPK pathway mutations except those with available therapies will be eligible. Patient must first enroll to the EAY191 master trial. Local molecular results may be used for enrollment. Submission of tissue at baseline is mandatory. Eligible patients will be randomized 1:1 to mFOLFOX6 vs mFOLFOX6 + binimetinib (45 mg oral twice a day every 14 days). Stratification factors include location and stage of disease. Primary efficacy analysis will compare OS in the intent-to-treat population. If the observed hazard ratio (HR) of experimental arm vs standard of care is < 0.545 (corresponding to an observed increase in OS by 5 months or longer), experimental treatment will be considered superior. An interim futility analysis at 50% of expected events will be conducted. If the observed HR is ≥ 1, experimental treatment will not be considered superior, and accrual maybe suspended. Secondary endpoints include progression-free survival, objective response rate, duration of response, disease control rate and toxicity of treatments. Exploratory objectives include prognostic modeling, correlations of genomic alterations with response or resistance and use of machine learning for outcome prediction. This study is active and open to accrual. Clinical trial information: NCT05564403 .

A phase 1, open-label, dose escalation and dose expansion study to evaluate the safety, tolerability, pharmacokinetics, and antitumor activity of PF-07799544 (ARRY-134) as a single agent and in combination with PF-07799933 BRAF dimer inhibitor, in participants 16 years and older with advanced solid tumors.

TPS3180 Background: The MAPK pathway plays a role in several key signaling and phosphorylation events that contribute to tumorigenesis. Inhibition of MEK, along with RAF kinases, has proven to be a successful transformative strategy for melanoma and other MAPK pathway-altered tumors. However, the duration of clinical benefit is limited by a narrow therapeutic index, de novo and acquired resistance and poor brain penetration. PF-07799544 is a next-generation, fully brain penetrant MEK inhibitor. PF-07799933 is an oral selective ATP-competitive small-molecule RAF kinase inhibitor that suppresses BRAF signaling in BRAF V600-mutant and non-V600-BRAF mutant tumors. It displays significantly less paradoxical activation than approved BRAFi and is not “pan RAF” as it spares non-BRAF mutated-containing RAF dimers. We describe here the design of the Phase 1 study of PF-07799544 as Monotherapy or in Combination with a next generation BRAF dimer inhibitor PF-07799933 in participants with BRAF mutated (BRAFm) advanced solid tumors. Methods: The purpose of this first-in-human study is to investigate the safety, tolerability, pharmacokinetics (PK), pharmacodynamics, and potential clinical benefits of PF-07799544 administered as a single agent in participants with advanced solid tumors (Phase 1a) and in combination with PF-07799933 in participants with BRAF Class 1, 2 and 3 mutated solid tumors with or without brain involvement (Phase 1b). Phase 1a will enroll participants with advanced solid tumors who have progressed on standard of care. The primary objective is to determine monotherapy MTD/RDE of PF-07799544. Once PK measurements indicate the potential for significant WT MEK mutation target coverage, participants with untreated and symptomatic brain metastases (bm) will be allowed to enroll. Phase 1b is comprised of multiple sub-studies, all of which evaluate PF-07799544 in combination with PF-07799933 in participants with BRAFm solid tumors who have progressed on standard of care therapies, including Class 1 BRAFi where indicated. Sub-study B: BRAFm melanoma (V600 and non-V600) will determine the MTDc/RDEc of the combination (Part 1 primary objective), followed by dose expansion cohorts (Part 2) (~80 participants): Cohort 1: BRAF V600 melanoma (asymptomatic and untreated bm permitted), Cohort 2: BRAF V600 melanoma (symptomatic bm), Cohort 3 BRAFm Class 2/3 melanoma (asymptomatic and untreated bm permitted); Sub-study C: BRAFm Class 2 or 3 advanced solid tumor Cohort 1 (asymptomatic and untreated bm permitted and Cohort 2 (symptomatic bm) (~20 each cohort). The main objectives of the dose expansion cohorts in all substudies, will be to evaluate anti-tumor activity, safety, PK and PD. Clinical trial information: NCT05538130 .

A first-in-human study of IK-595, an oral MEK/RAF molecular glue, in patients with RAS- or RAF-altered advanced solid tumors.

TPS3185 Background: Alterations in the RAS/RAF/MEK/ERK pathway are the most common drivers of oncogenesis. MEK is a clinically validated cancer target and despite FDA approval of several MEK inhibitors, their clinical utility has been limited to BRAF V600 mutant cancers and NF1 mutant neurofibromas mostly due to early emergence of resistance and low therapeutic indices. IK-595, a potent novel MEK-RAF molecular glue, is being developed to overcome these limitations. IK-595 traps MEK in an inactive complex with all RAF isoforms and blocks RAF-dependent MEK phosphorylation, thereby alleviating CRAF-mediated MEK reactivation that hinders the efficacy of approved MEK inhibitors in RAS/RAF-driven tumors, in addition to kinase independent CRAF activity. IK-595 exhibits potent single agent activity in a wide range of in vivo cancer models harboring various RAS/RAF alterations, including, but not limited to, lung, pancreatic, colorectal cancer (CRC), melanoma, and AML. The preclinical pharmacokinetic profile of IK-595 also enables flexible dosing schedules resulting in a broader therapeutic window. Methods: This is a phase 1, first-in-human, open-label, multicenter study to evaluate IK-595 as monotherapy in patients with RAS- or RAF-altered advanced solid tumors for whom there are no other further treatment options known to confer clinical benefit. Dose escalation uses a Bayesian Optimal Interval Design (BOIN) in patients with advanced and unresectable, or metastatic solid tumors with confirmed RAS/RAF gene alterations. Backfilling of cleared dose levels with key target indications will initiate upon achievement of efficacious plasma exposures. Dose expansion will occur in genetically defined cohorts, for example NRAS-mutant CRC and malignant melanoma, as well as BRAF non-V600 and KRAS mutant tumors using a Simon 2-stage adaptive design. IK-595 will initially be administered on an intermittent dosing schedule in 30-day cycles. Additional dosing schedules may be explored. Primary objectives of the study are to evaluate safety and tolerability of IK-595 and to determine the recommended phase 2 dose (RP2D) and/or maximum tolerated dose (MTD). Secondary objectives include evaluation of preliminary antitumor activity by RECIST 1.1, pharmacokinetic (PK) parameters, and pharmacodynamic effects of IK-595 on pERK in paired tumor biopsies. Key exploratory endpoints include changes in pERK in peripheral blood cells, changes in pERK target genes in tumor biopsies, and assessment of candidate baseline response biomarkers. The study began in December 2023 and enrollment in Cohort 1 was completed with no DLTs; dose escalation continues to enroll. Clinical trial information: NCT.

Cobimetinib plus atezolizumab for RAS and NF1/2-mutated poorly differentiated thyroid carcinoma.

6106 Background: Poorly differentiated thyroid carcinomas (PDTC) are a subset of thyroid cancers characterized by high-grade pathologic features. They hold an intermediate position on the spectrum of follicular-derived thyroid cancers. Due to their more aggressive clinical behavior, PDTCs typically exhibit shorter responses to the usual kinase inhibitors (KIs) used in advanced differentiated thyroid cancers and develop resistance earlier on. In fact, median progression free survival (PFS) with single-agent lenvatinib in patients with PDTC in the SELECT trial (n=28) was 14.8 months. Although there are increasing data to support the use of immunotherapy plus KI combinations in anaplastic thyroid cancer, evidence demonstrating the efficacy of this strategy in PDTC is sparse. We aimed to study the safety and efficacy of atezolizumab combined with KIs in PDTC. Methods: We enrolledpatientswith PDTC in a single-center phase II prospective trial of atezolizumab plus mutation-determined targeted therapy (NCT03181100). Patients with RAS or NF- mutated tumors were treated with atezolizumab plus the MEK inhibitor (MEKi) cobimetinib. Primary outcome was median overall survival (mOS). Best response to therapy was assessed per RECIST v1.1; survival by the Kaplan-Meier method. Results: Eight patients with RAS/NF-mutated PDTC were enrolled. Median age at treatment start was 68.5 years. All patients had distant metastatic disease at time of enrollment. Prior to study entrance, 7/8 patients (88%) had surgical resection of the primary tumor, 6/8 (75%) radioactive iodine, 2/8 (25%) external beam radiation to the neck, and 3/8 (38%) bridging cytotoxic chemotherapy. All patients were naïve to KIs. Six (75%) patients had RAS mutations (1 HRAS, 3 KRAS, 2 NRAS) and 3 (38%) had NF mutations (2 NF1, 1 NF2). One patient’s tumor harbored both KRAS and NF2 mutations at baseline. PD-L1 score was positive in 3/4 evaluable specimens. Median duration of follow-up was 65 months. Best response to therapy was stable disease in 6/8 (75%), partial response in 1/8 (12.5%) and progressive disease in 1/8 (12.5%). mOS was 23 months (95% CI, 12.8 – 33.2) and median PFS was 7 months (95% CI, 2.4 – 11.6). 4/8 patients received radioactive iodine (RAI) while on systemic therapy. Median dose of RAI was 149 millicuries (range, 108 – 153). mOS was significantly longer in patients who received RAI (32 vs 16 months; p= 0.034). The combination of cobimetinib + atezolizumab was overall well tolerated, with an expected adverse event profile. Conclusions: In patients with metastatic PDTC driven by RAS or NFmutations, combination of the anti-PD-L1 atezolizumab with MEKi cobimetinib showed some clinical efficacy, although PFS was shorter than with single-agent lenvatinib. However, SELECT trial did not delineate responses by driver mutations. This combination could thus be considered in selected patients at high risk of complications with antiangiogenic KIs. Clinical trial information: NCT03181100 .

CD44 and CD271 expression and chemoresistance in BRAF V600E/K mutation–positive melanoma.

e21542 Background: Melanoma stem cells (MSC) are thought to play a role in cellular proliferation, migration, and chemotherapeutic resistance. We investigated native expression of several putative MSC biomarkers in human BRAF V600E/K mutation positive melanoma cell lines of different phases—radial growth phase (WM35), vertical growth phase (WM278)—and metastatic (LM-Mel-45, LM-Mel-71) cell lines. We examined cell viability of select cell subpopulations during in vitro treatment with BRAF and MEK inhibitor monotherapy and combination therapy. Methods: Using flow cytometry, we assessed surface expression of putative MSC biomarkers: CD44, CD271, CD133, CD186, and CD20. We sorted each cell line by CD44 and CD271 expression with a predetermined hierarchical gating strategy and compared 4 chemotherapy conditions: control, BRAF inhibition with 1.25 µM dabrafenib, MEK inhibition with 0.125 µM trametinib, and combination therapy. Cells (25,000) were collected directly into chemotherapy treated media and incubated for 72 hours. Cell viability was measured by MTT assay. Statistical analysis used mixed-effects ANOVA and Tukey HSD. Results: No significant expression of CD133, CD186, or CD20 was found in any cell line. Over 99% of live cells were CD44+ in all 4 cell lines. Only WM35 and LM-Mel-71 had both CD44+/CD271+ and CD44+/CD271- subpopulations. CD271 expression was restricted to CD44+ cells. Among live cells, the CD44+/CD271+ subpopulation was 31.2% for WM35 and 14.4% for LM-Mel-71. For WM35, cell viability in CD44+/CD271+ cells was greater than CD44+/CD271- cells for all treatments (p < 0.001). For LM-Mel-71 cells, CD271 expression did not affect cell viability within any treatment (p = 0.64). For chemotherapeutic treatments, cell viability in CD44+/CD271- subpopulation was higher in LM-Mel-45 cells than WM278 (p < 0.03) or LM-Mel-71 (p < 0.002), but not WM35 cells (p > 0.05). Trametinib monotherapy and combination therapy had similar cell viability in all 4 cell lines (p > 0.05). Conclusions: To our knowledge, our study is the first to show differences in phenotypic expression of CD44 and CD271 across nonmetastatic and metastatic melanoma cell lines and suggests co-expression of CD44 and CD271 confers increased chemotherapeutic resistance to in vitro BRAF and MEK inhibitor treatment in radial growth phase but not metastatic melanoma. More research is needed to better understand the role of CD44 and CD271 co-expression in melanoma initiation, progression, and chemotherapeutic resistance. CD271 remains a potential immunotherapeutic drug target in the treatment of BRAF V600E/K mutation positive melanoma.

Beacon: A phase II study of bevacizumab, atezolizumab, and cobimetinib in patients with recurrent, platinum resistant, high grade serous ovarian cancer.

5565 Background: Platinum resistant high grade serous ovarian cancer (HGSC) is associated with a poor prognosis and limited treatment options. Immune checkpoint inhibitors have failed to show significant impact in treatment of HGSC to date. Bevacizumab (anti-VEGF) and atezolizumab (anti-PDL1) have shown synergy in multiple cancer types. Cobimetinib (MEK inhibitor) may also potentiate immune responses, particularly by altering the tumour microenvironment. We sought to evaluate the efficacy of cobimetinib, bevacizumab and atezolizumab in women with platinum resistant HGSC. Methods: BEACON is a Phase II single arm study of cobimetinib (60mg oral D1-21 q 28-days), bevacizumab (5mg/kg IV q2w) and atezolizumab (840mg IV q2w from Cycle 2) in patients with platinum-resistant recurrent HGSC. Patients continued therapy until progression or unacceptable toxicity. The primary endpoint was overall response rate (ORR) according to RECIST 1.1 at 24 weeks. Secondary endpoints included best overall response (BOR), safety, progression free survival, and response duration. Correlative studies on paired tumor biopsy and blood samples will explore molecular characteristics/subtypes and potential biomarkers of response as exploratory objectives. This study has now completed accrual and we present the 24-week response data, with a data cut off 21st December 2023. Results: Twenty-nine patients were enrolled between September 2018 and June 2023. Median age was 62 years (range 37 - 79) and 97% had received ≥ 2 prior lines of chemotherapy. The median number of cycles received was 3 cycles of atezolizumab and cobimetinib, and 4 cycles of bevacizumab. The ORR at 24 weeks was 21% [95% CI: 8-40], and a further 28% had stable disease as assessed per RECIST. Five patients (17%) have remained on study treatment for ≥ 52 weeks to date, suggesting that in some patients there was durable disease control. In terms of safety, 22 patients (76%) required a dose reduction in cobimetinib, mainly due to gastrointestinal and skin toxicity. Seventeen patients (59%) experienced a ≥Grade 3 treatment related adverse event, most commonly hypertension (6 patients, 21%). Two patients (7%) discontinued all study treatments due to toxicity. Conclusions: Preliminary results from this study show promising efficacy with the combination of atezolizumab, bevacizumab and cobimetinib in platinum resistant HGSC. Duration of response, progression free survival data and translational data exploring molecular characteristics will be presented as data matures. Clinical trial information: NCT03363867 . [Table: see text]

Real-world experience with targeted therapy in patients with histiocytic neoplasms in the Netherlands and in Belgium

AbstractHistiocytic disorders are rare hematologic neoplasms characterized by a notable dependence on mitogen-activated protein kinase signaling. Targeted therapy is an emerging treatment option, yet the number of reported patients remains limited. Here, we describe 40 patients with histiocytic neoplasms who were treated with targeted therapy in 7 tertiary referral hospitals from the Netherlands and Belgium. The cohort comprised of 6 (15%) children and 34 (85%) adults with diverse histiocytoses, including Langerhans cell histiocytosis (LCH; n = 12), Erdheim–Chester disease (n = 14), central nervous system xanthogranuloma (n = 2), Rosai–Dorfman disease (n = 3), histiocytic sarcoma (n = 2), ALK–positive histiocytosis (n = 1), and mixed/unclassifiable histiocytosis (n = 6). Five patients were included in a clinical trial; 35 (88%) received BRAF/MEK inhibitors outside of trials. Among these 35 patients with available follow-up data, median time on targeted treatment was 1.9 years (range, 0.04-5.8 years). Complete or partial responses were observed in 25 of 27 (93%) patients treated for multisystemic and/or solid lesions and 2 of 8 (25%) patients treated for neurodegenerative LCH. Responses were generally durable, although 10 patients lost response after dose reduction or therapy interruption. Responses were recaptured in 9 of 10 cases. Two patients developed new or progressive neurodegenerative lesions: 1 during and 1 after vemurafenib therapy. At last follow-up, 8 adults had stopped targeted therapy because of toxicity. This study corroborates the favorable outcomes of BRAF/MEK inhibition in patients with histiocytosis described previously. However, it also highlights limitations and calls for prospective studies.

RNA Therapy for Oncogenic NRAS-Driven Nevi Induces Apoptosis

RAS proteins regulate cell division, differentiation and apoptosis via multiple downstream effector pathways. Oncogenic RAS variants are the commonest drivers in cancers, however they also drive many benign lesions predisposing to malignancy, such as melanocytic naevi, thyroid nodules, and colonic polyps. Reversal of these benign lesions could reduce cancer incidence, however the effects of oncogenic RAS have been notoriously difficult to target with downstream pathway inhibitors. Here we show effective suppression of oncogenic and currently undruggable NRASQ61K in primary cells from melanocytic naevi using siRNA targeted to the recurrent causal variant. This results in striking reduction in expression of ARL6IP1, a known inhibitor of endoplasmic reticulum stress-induced apoptosis not previously linked to NRAS. We go on to show that a single dose of siRNA in primary cells triggers an apoptotic cascade, in contrast to treatment with a MEK inhibitor. Protective packaging of the targeted siRNA into lipid nanoparticles permits successful delivery into a humanised mouse model of melanocytic naevi, and results in variant NRAS knockdown in vivo. These data show that RAS-induced protection from apoptosis is involved in persistence of NRAS-driven melanocytic naevi and anticipate that targeted siRNA could form the basis of clinical trials for RAS-driven benign tumours.

State of the Art in Low-Grade Glioma Management: Insights From Isocitrate Dehydrogenase and Beyond.

Low-grade gliomas present a formidable challenge in neuro-oncology because of the challenges imposed by the blood-brain barrier, predilection for the young adult population, and propensity for recurrence. In the past two decades, the systematic examination of genomic alterations in adults and children with primary brain tumors has uncovered profound new insights into the pathogenesis of these tumors, resulting in more accurate tumor classification and prognostication. It also identified several common recurrent genomic alterations that now define specific brain tumor subtypes and have provided a new opportunity for molecularly targeted therapeutic intervention. Adult-type diffuse low-grade gliomas are frequently associated with mutations in isocitrate dehydrogenase 1 and 2 (IDH1/2), resulting in production of 2-hydroxyglutarate, an oncometabolite important for tumorigenesis. Recent studies of IDH inhibitors have yielded promising results in patients at early stages of disease with prolonged progression-free survival (PFS) and delayed time to radiation and chemotherapy. Pediatric-type gliomas have high rates of alterations in BRAF, including BRAF V600E point mutations or BRAF-KIAA1549 rearrangements. BRAF inhibitors, often combined with MEK inhibitors, have resulted in radiographic response and improved PFS in these patients. This article reviews emerging approaches to the treatment of low-grade gliomas, including a discussion of targeted therapies and how they integrate with the current treatment modalities of surgical resection, chemotherapy, and radiation.

An open-label study to assess the safety and efficacy of naporafenib (ERAS-254) administered with trametinib in previously treated patients with locally advanced unresectable or metastatic solid tumor malignancies with RAS Q61X mutations (SEACRAFT-1).

TPS3178 Background: The rat sarcoma viral oncogene (RAS)/mitogen-activated protein kinase (MAPK) pathway is a key signaling cascade that drives cell proliferation, differentiation, and survival. Inappropriate activation of this pathway drives tumorigenesis in a subset of solid tumors. There are 3 isoforms of RAS (KRAS, NRAS, and HRAS) with the most commonly mutated codons being 12, 13, and 61. While these codon mutations map to the active site of RAS, they appear to have differential impacts on pathway activation. Mutations at codon 61 (RAS Q61X) are generally thought to be the most MAPK pathway-activating relative to mutations at codons 12 and 13 and are therefore thought to be the most oncogenic. Naporafenib is a pan-RAF inhibitor that is being evaluated in combination with trametinib, which inhibits MEK, a downstream node of the RAS/MAPK pathway. Clinical proof of concept (PoC) in patients with NRASm melanoma (of which 80 to 90% have Q61X mutations) and preliminary PoC for patients with RAS Q61X NSCLC have been established for the combination. Preclinical data across tumor types suggest that RAS Q61X is a potential predictive biomarker for the combination of naporafenib with trametinib, a hypothesis being tested in this trial. Methods: SEACRAFT-1 (NCT05907304) is a Phase 1b, open-label study evaluating the clinical activity and safety of the combination of naporafenib and trametinib in pts with locally advanced, unresectable, or metastatic solid tumor malignancies that are not responsive to standard therapies or for which there are no standard therapies. Eligible pts must be ≥18 years (or ≥12 and <18 years in an adolescent substudy) with documented RAS Q61X mutation by an analytically validated assay. Pts must also have ≥1 measurable lesion per RECIST (Response Evaluation Criteria in Solid Tumors, v1.1) and Eastern Cooperative Oncology Group (ECOG) Performance Status ≤2 (or Karnofsky/Lansky Performance Status ≥70 for adolescent pts). Exclusion criteria include prior therapy with an ERK, MEK, RAF, or RAS inhibitor, QTcF >450 ms at baseline, and left ventricular ejection fraction (LVEF) <50% at baseline. A total of up to 115 pts will be enrolled to receive naporafenib 200 mg BID and trametinib 1 mg QD continuous in 28-day cycles until disease progression, unacceptable toxicity, or withdrawal of consent. The primary endpoint is ORR; secondary endpoints include assessment of PFS, DOR, safety, and tolerability. Clinical trial information: NCT05907304 .

Nab-paclitaxel and gemcitabine (modified) in combination with oral cobimetinib and encorafenib following FOLFIRINOX in patients with metastatic G12D and G12V pancreatic cancer.

e16330 Background: Pancreatic cancer is the only human cancer in which most of the tumors are KRAS mutated. A majority of the mutations occur in codon 12. Mutations percentages are as follows: G12D (50%), G12V (35%) and G12R(12%). We are reporting on a pilot study in patients with advanced pancreatic cancer who have failed, or have become resistant to FOLFIRINOX. Thereafter the patients were placed on Nab-paclitaxel and Gemcitabine in combination with oral Cobimetinib and encorafenib. Methods: Patients with advanced pancreatic cancers are typically offered modified FOLFIRINOX followed by Nab-paclitaxel and Gemcitabine. After obtaining a written informed consent, we conducted a single arm study of patients with pathologic proven unresectable metastatic pancreatic cancer. Patients who had failed FOLFRINOX were placed on a modified regimen of Gemcitabine (1000mg/m2) and Nab-paclitaxel (125 mg/M2) on days 1 and 15 every 28-day cycle. Oral medications, Cobimetinib 20 mg bid and encorafenib of 150 mg bid were given. The oral chemotherapies were administered weekdays only during the 28-day cycle. The primary end point was to determine the response rate from the time the patients were placed on Nab-paclitaxel and Gemcitabine and the oral medication. The secondary endpoint was to assess the overall survivorship from the beginning of the therapy, and overall toxicities of the combination therapy. Twelve patients with advanced metastatic pancreatic cancer were enrolled on this pilot study. Six patients were male, and the median age was 67 years. Liver metastases were present in eight patients. Treatment was continued as long as there was no disease progression. CBC, CMP, CA19-9 was performed every other week. CT and PET scan was ordered every eight weeks. Results: Overall follow up is from 5 to 19 months (median 14 months). Segmental median survival from the start of oral therapy in conjunction with Nab-paclitaxel and Gemcitabine is 5 months (2-9 months). As from now,all patients are alive and 10 of 12 patients are on therapy. One patient who achieved pathologic response in the liver was deemed operable, and pathologically the distal pancreatectomy demonstrated NO disease. The other patient has progressed and is not on treatment. Grade 3 non-hematological toxicities included nausea, vomiting and fatigue in 3 of 12 patients. Hematological toxicities included neutropenia and neutrophil support was needed in 6 out of 12 patients. Median survivorship has NOT been reached. In this small study, we have observed a rapid and dramatic reduction in tumor volume. Conclusions: The combination of MEK and BRAF inhibitors with chemotherapy may be potentially active in pancreatic tumors (G12D and G12V). Based on the data presented, Nab-paclitaxel and Gemcitabine in combination with oral Cobimetinib and encorafenib needs to be further explored in a larger cohort of patients.

A phase II study of tunlametinib in combination with vemurafenib in patients with BRAF V600-mutant advanced melanoma.

e21519 Background: The new MEK inhibitor tunlametinib combined with the BRAF inhibitor vemurafenib showed promising clinical activity in patients (pts) with BRAF V600-mutant solid tumors in a previous Phase I study (NCT03976050). Based on the result, we designed a phase IIa study to evaluate the efficacy and safety of tunlametinib plus vemurafenib in Chinese pts with BRAF V600 mutant melanoma. Methods: This open-label, single arm, multiple-center phase IIa study enrolled Chinese pts with BRAF V600E-mutant advanced melanoma, without restriction on the disease subtype (e.g., acral, mucosal, or cutaneous melanoma). Prior treatment was permitted, excluding BRAF/MEK inhibitors. Pts received oral tunlametinib at a dose of 9 mg twice daily and vemurafenib 720 mg twice daily. The primary endpoint was the objective response rate (ORR) per RECIST v1.1. Results: Between October 15, 2021, and June 22nd, 2022, 17 pts were enrolled and included in the analysis. Thirteen (76.5%) pts had received previous systemic antitumor therapy, with 12 (70.6%) receiving immunotherapy. Seven (41.2%) pts had acral melanoma, 8 (47.1%) pts had skin melanoma (non-acral) and 2 (11.8%) pts had mucosal melanoma. All pts had metastatic disease. With a median follow-up of 15.3 months (95%CI: 6.8; NE), 12 (70.6%) pts achieved confirmed partial response (PR), resulting in a confirmed ORR of 70.6% (95% CI: 44.0%-89.7%). The disease control rate was 100% (95% CI: 80.5%, 100.0%). The median progression-free survival (PFS) was 10.0 months (95% CI: 5. 5, NE). the duration of response (DOR) was 20.1 (95% CI: 4.2, NE). The overall survival (OS) was 21.6 months (95% CI: 14.5, NE), with a 12-months OS rate of 87.4% (95% CI: 58.1%, 96.7%). Subgroup analysis revealed that in pre-treated pts, the confirmed ORR was 76.9% (95% CI: 46.2%, 95.0%), the median PFS was 10.0 months (95% CI: 5.5, NE), while in previous untreated pts, the mPFS was 14.0 months (95% CI: 9.9, NE). In pts with skin melanoma, the confirmed ORR was 87.5% (47.3%, 99.7%), the mPFS was 10.0 months (95% CI: 5.5, NE), the mOS was 21.6 months (95% CI: 5.7, NE). In pts with acral melanoma, the ORR was 57.1% (95% CI: 18.4%,90.1%), the mPFS was 18.1 months (95% CI: 2.8, NE), the mOS not reached (12.3, NE). The most common adverse events included rash, pyrexia, and elevated blood creatin phosphokinase, most of which were of grade 1-2 severity. Grade 3 or higher TRAEs occurred in 12 (70.6%) pts, of which 41.2% were rash. Most AEs were manageable with supportive therapy or dose interruption. No treatment-related deaths were reported. Conclusions: The addition of a MEK inhibitor tunlametinib to vemurafenibexhibited promising clinical efficacy in Chinese patients with BRAF V600-mutant advanced melanoma, with a manageable safety profile. Additionally, notable effects were observed in pts with acral melanoma. The efficacy in pre-treated patients was comparable to that of similar agents in previous untreated patients. Clinical trial information: NCT05263453 .

Targeting nerve growth factor-mediated osteosarcoma metastasis: mechanistic insights and therapeutic opportunities using larotrectinib

Osteosarcoma (OS) therapy presents numerous challenges, due largely to a low survival rate following metastasis onset. Nerve growth factor (NGF) has been implicated in the metastasis and progression of various cancers; however, the mechanism by which NGF promotes metastasis in osteosarcoma has yet to be elucidated. This study investigated the influence of NGF on the migration and metastasis of osteosarcoma patients (88 cases) as well as the underlying molecular mechanisms, based on RNA-sequencing and gene expression data from a public database (TARGET-OS). In osteosarcoma patients, the expression of NGF was significantly higher than that of other growth factors. This observation was confirmed in bone tissue arrays from 91 osteosarcoma patients, in which the expression levels of NGF and matrix metallopeptidase-2 (MMP-2) protein were significantly higher than in normal bone, and strongly correlated with tumor stage. In summary, NGF is positively correlated with MMP-2 in human osteosarcoma tissue and NGF promotes osteosarcoma cell metastasis by upregulating MMP-2 expression. In cellular experiments using human osteosarcoma cells (143B and MG63), NGF upregulated MMP-2 expression and promoted wound healing, cell migration, and cell invasion. Pre-treatment with MEK and ERK inhibitors or siRNA attenuated the effects of NGF on cell migration and invasion. Stimulation with NGF was shown to promote phosphorylation along the MEK/ERK signaling pathway and decrease the expression of microRNA-92a-1-5p (miR-92a-1-5p). In in vivo experiments involving an orthotopic mouse model, the overexpression of NGF enhanced the effects of NGF on lung metastasis. Note that larotrectinib (a tropomyosin kinase receptor) strongly inhibited the effect of NGF on lung metastasis. In conclusion, it appears that NGF promotes MMP-2-dependent cell migration by inhibiting the effects of miR-92a-1-5p via the MEK/ERK signaling cascade. Larotrectinib emerged as a potential drug for the treatment of NGF-mediated metastasis in osteosarcoma.

Side effects of dermato-oncologic therapies

Immune checkpoint inhibitors (ICIs) such as PD(L)1 and CTLA4 antibodies as well as targeted therapies such as BRAF and MEK inhibitors have significantly improved the systemic treatment of skin cancer in adjuvant and advanced therapy settings. All these drugs differ in their spectrum of side effects. The aim of this article is to provide an overview of the spectrum of side effects of dermato-oncological therapies and their management, taking into account the current literature. The most important side effects of ICIs, the CCR4 inhibitor mogamulizumab, the ImmTAC tebentafusp, the BRAF and MEK inhibitors and the multityrosine kinase inhibitor imatinib are considered. Side effects can manifest themselves in all organ systems. Chronic side effects and long-term harm are possible, especially with ICIs, and require close therapy monitoring and patient education. Knowledge of the side effects and the temporal, sometimes delayed course of their occurrence are essential for diagnosis and prompt initiation of therapy.

Regorafenib in patients with pretreated advanced melanoma: a single-center case series.

Melanoma patients failing all approved treatment options have a poor prognosis. The antimelanoma activity of regorafenib (REGO), a multitargeted kinase inhibitor, has not been investigated in this patient population. The objective response rate and safety of REGO treatment in advanced melanoma patients was investigated retrospectively. Twenty-seven patients received REGO treatment. All patients had progressed on anti-programmed cell death protein 1 (PD-1) and anti-cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) checkpoint inhibition and BRAF/MEK inhibitors (in case of a BRAF V600 mutation). REGO was administered in continuous dosing and combined (upfront or sequentially) with nivolumab ( n = 5), trametinib ( n = 8), binimetinib ( n = 2), encorafenib ( n = 1), dabrafenib/trametinib ( n = 9), or encorafenib/binimetinib ( n = 7). The best overall response was partial response (PR) in five patients (18.5%) and stable disease in three patients (11.1%). Three of seven (42.8%) BRAF V600mut patients treated with REGO in combination with BRAF/MEK inhibitors obtained a PR (including regression of brain metastases in all three patients). In addition, PR was documented in a BRAF V600mut patient treated with REGO plus anti-PD-1, and a NRASQ61mut patient treated with REGO plus a MEK inhibitor. Common grade 3-4 treatment-related adverse events included arterial hypertension ( n = 7), elevated transaminase levels ( n = 5), abdominal pain ( n = 3), colitis ( n = 2), anorexia ( n = 1), diarrhea ( n = 1), fever ( n = 1), duodenal perforation ( n = 1), and colonic bleeding ( n = 1). Median progression-free survival was 11.0 weeks (95% confidence interval, 7.1-14.9); median overall survival was 23.1 weeks (95% confidence interval, 13.0-33.3). REGO has a manageable safety profile in advanced melanoma patients, in monotherapy as well as combined with BRAF/MEK inhibitors or PD-1 blocking monoclonal antibodies. The triplet combination of REGO with BRAF/MEK inhibitors appears most active, particularly in the BRAF V600mut patients.

Long-term outcome and prognosis of mixed histiocytosis (Erdheim-Chester disease and Langerhans Cell Histiocytosis)

Erdheim-Chester disease (ECD) is a rare histiocytosis that may overlap with Langerhans Cell Histiocytosis (LCH). This "mixed" entity is poorly characterized. We here investigated the clinical phenotype, outcome, and prognostic factors of a large cohort of patients with mixed ECD-LCH. This retrospective study was performed at two referral centers in France and Italy (Pitié-Salpêtrière Hospital, Paris; Meyer Children's Hospital, Florence). We included children and adults with ECD diagnosed in 2000-2022 who had biopsy-proven LCH, available data on clinical presentation, treatment and outcome, and a minimum follow-up of one year. Outcomes included differences in clinical presentation and survival between mixed ECD-LCH and isolated ECD; we also investigated response to treatments and predictors of survival in the mixed cohort. Survival was analyzed using the Kaplan-Maier method and differences in survival with the long-rank test. Cox regression models were used to evaluate the potential impact of age and gender on survival and to identify predictors of non-response and survival. Out of a cohort of 502 ECD patients, 69 (14%) had mixed ECD-LCH. Compared to isolated ECD, mixed ECD-LCH occurred more frequently in females (51 vs. 26%, p<0.001) and in patients with multisystem disease (≥4 sites). Mixed ECD-LCH more frequently involved long bones (91 vs. 79%, p=0.014), central nervous system (51vs. 34%, p=0.007), facial/orbit (52 vs. 38%, p=0.031), lungs (43 vs. 28%, p=0.009), hypothalamic/pituitary axis (51 vs. 26%, p<0.001), skin (61 vs. 29%, p<0.001), and lymph nodes (15 vs. 7%, p=0.028); the BRAFV600E mutation was also more frequent in mixed ECD-LCH (81 vs. 59%, p<0.001). Targeted treatments (BRAF and/or MEK inhibitors) induced response more frequently than conventional therapies (interferon-α, chemotherapy), either as first-line (77 vs. 29%, p<0.001) or as any line (75 vs. 24%, p<0.001). After a median follow-up of 71 months, 24patients (35%) died. Survival probability was comparable between ECD alone and mixed ECD-LCH (log-rank p=0.948). At multivariable analysis, age at diagnosis (HR 1.052, 95% CI 1.008-1.096), associated hematologic conditions (HR 3.030, 95% CI 1.040-8.827), and treatment failure (HR 9.736, 95% CI 2.919-32.481) were associated with an increased risk of death, while lytic bone lesions with a lower risk (HR 0.116, 95% CI 0.031-0.432). Mixed ECD-LCH is a multisystem disease driven by the BRAFV600E mutation and targeted treatments are effective. Age at diagnosis, bone lesion patterns, associated hematologic conditions, and treatment failure are the main predictors of death in mixed ECD-LCH. None.

Endogenous oncogenic KRAS expression increases cell proliferation and motility in near-diploid hTERT RPE-1 cells

About 18% of all human cancers carry a mutation in the KRAS gene making it among the most sought-after anti-cancer targets. However, mutant KRas protein has proved remarkably undruggable. The recent approval of the first generation of RAS inhibitors therefore marks a seminal milestone in the history of cancer research. Inevitably though, it also raises the predictable challenges of limited drug efficacies and acquired resistance. Hence, new approaches that improve our understanding of the tumorigenic mechanisms of oncogenic RAS within more physiological settings continue to be essential. Here, we have employed the near-diploid human hTERT RPE-1 cells to generate isogenic cell lines in which one of the endogenous KRAS alleles carries an oncogenic KRAS mutation at glycine 12. Cells with a KRASG12V/+, KRASG12C/+, or KRASG12D/+ genotype, together with wild-type KRASG12G(WT)/+ cells, reveal that oncogenic KRAS.G12X mutations increase cell proliferation rate and cell motility and reduced focal adhesions in KRASG12V/+ cells. EGF-induced phosphorylation of ERK and AKT was comparable between KRASG12V/+, KRASG12C/+, KRASG12D/+, and KRASG12G(WT)/+ cells. Interestingly, KRASG12X/+ cells showed varying responses to distinct inhibitors with the KRASG12V/+ and KRASG12D/+ cells more sensitive to hydroxyurea and MEK inhibitors, U0126 and trametinib, but more resistant to PI3K inhibitor, PIK-90, than the KRASG12G(WT)/+ cells. A combination of low doses of hydroxyurea and U0126 showed an additive inhibition on growth rate that was greater in KRASG12V/+ than wild-type cells. Collectively, these cell lines will be a valuable resource for studying oncogenic RAS signalling and developing effective anti-KRAS reagents with minimum cytotoxicity on wild-type cells.

Continuous response despite reduced dose of trametinib as single agent in an adolescent with a relapsed disseminated pediatric low-grade glioma KIAA1549-BRAF fusion positive: a case report and review of the literature

Dissemination in pediatric low-grade glioma may occur in about 4%–10% of patients according to retrospective cohort studies. Due to its low incidence, there is no consensus on treatment for these patients. According to the constitutional activation of the MAPK/ERK pathway in these tumors, MEK inhibitors such as trametinib have been used successfully in the relapsed setting. Skin toxicity is frequent in patients receiving trametinib, normally mild to moderate, but sometimes severe, needing to discontinue the drug, limiting the efficacy in the tumor. There is not much information in the literature regarding whether reducing the dose of trametinib is able to maintain efficacy while, at the same time, decreasing toxicity. Here, we present an adolescent, with severe skin toxicity, whose trametinib dose was reduced by 50% and efficacy on the tumor continued while skin toxicity significantly decreased.