Mitogen-activated Protein Kinase Pathway Alterations Research Articles

Abstract 1709: MAPK pathway alterations are a targetable vulnerability in bladder cancer

Abstract Bladder cancer (BC) is the fourth most common cancer in males and accounts for about 80,000 new cases in the US. Approximately 25% patients with BC will present with muscle-invasive bladder cancer (MIBC) and for the past several decades the standard-of-care for MIBC and metastatic bladder cancer has been cisplatin-based chemotherapy. More recently, multiple immunotherapeutic agents have been approved but only a subset of patients respond to these treatments and therefore novel therapeutic strategies are needed to expand treatment options and improve clinical outcomes for BC patients. Large-scale genomic studies of MIBC have identified numerous recurrent genomic alterations including mutations, copy number alterations, and chromosomal translocations. Using publicly available patient datasets, we identified ~20% of MIBC patients harboring alterations in genes involved in the mitogen-activated protein kinase (MAPK) pathway and their upstream activators. RAF1 copy number amplification was the most predominant alteration followed by activating HRAS mutations. Leveraging our institutional cohorts of bladder cancer specimens, we defined the frequency of these alterations and validated RAF1 amplification in a subset of cases using fluorescence in situ hybridization. To functionally define the role of MAPK pathway alterations in BC, we tested activity of RAF and MEK inhibitors in BC cell line models with diverse MAPK pathway alterations including RAF1 amplification and HRAS/NRAS mutations. We found that these MAPK pathway altered models displayed increased sensitivity to RAF/MEK inhibition compared to MAPK-unaltered models. We further demonstrated the feasibility of preclinically targeting these alterations in mouse models of BC using cell line and patient-derived-xenografts. Additionally, we tested the impact of MAPK pathway modulation on tumor extrinsic properties including changes in the tumor microenvironment that could potentially affect responses to immunotherapeutic agents. Taken together, we have identified MAPK pathway alterations as a novel dependency in BC that can be targeted with emerging RAF inhibitors. Citation Format: Raie Bekele, Amruta Samant, Timothy Hanlon, Kent Mouw. MAPK pathway alterations are a targetable vulnerability in bladder cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1709.

Combined MEK/MDM2 inhibition demonstrates antitumor efficacy in TP53 wild-type thyroid and colorectal cancers with MAPK alterations

Most tumors with activating MAPK (mitogen-activated protein kinase) pathway alterations respond poorly to MEK inhibitors alone. Here, we evaluated combination therapy with MEK inhibitor selumetinib and MDM2 inhibitor KRT-232 in TP53 wild-type and MAPK altered colon and thyroid cancer models. In vitro, we showed synergy between selumetinib and KRT-232 on cell proliferation and colony formation assays. Immunoblotting confirmed p53 upregulation and MEK pathway inhibition. The combination was tested in vivo in seven patient-derived xenograft (PDX) models (five colorectal carcinoma and two papillary thyroid carcinoma models) with different KRAS, BRAF, and NRAS mutations. Combination therapy significantly prolonged event-free survival compared with monotherapy in six of seven models tested. Reverse-phase protein arrays and immunohistochemistry, respectively, demonstrated upregulation of the p53 pathway and in two models cleaved caspase 3 with combination therapy. In summary, combined inhibition of MEK and MDM2 upregulated p53 expression, inhibited MAPK signaling and demonstrated greater antitumor efficacy than single drug therapy in both in vitro and in vivo settings. These findings support further clinical testing of the MEK/MDM2 inhibitor combination in tumors of epithelial origin with MAPK pathway alterations.

Efficacy of Cobimetinib in Rosai-Dorfman Disease

▪INTRODUCTIONRosai-Dorfman disease (RDD) is a rare histiocytic disorder associated with histiocytes expressing high level of macrophage colony stimulating factor receptor (c-fms). Mutations in mitogen-activated protein kinase (MAPK) pathway have been reported in RDD, indicating an underlying clonal process in some patients. Aberrant activation of MAPK pathway can occur due to mutations or high c-fms expression. Data on the use of MAPK/extracellular-signal-related kinase (ERK)-inhibitor therapy in RDD are very limited. Cobimetinib is a MEK inhibitor, which is listed in the National Comprehensive Cancer Network Compendium ® for the treatment of RDD. We present our retrospective experience of cobimetinib treatment in a large series of patients with RDD.METHODSFollowing approval of the institutional reviewed board, patients (pts) with RDD who were consecutively seen at Mayo Clinic and treated with cobimetinib between 2013-2021 were included. Response was assessed as described by Goyal et al (Haematologica 2020;105:2). Cobimetinib was given 20-60 mg once a day by mouth for 21 days in a 28-day cycle. Adverse events (AEs) were graded using the National Cancer Institute Common Toxicity Criteria v5.0. Time-to-event analyses were calculated from the time of treatment initiation, while duration of response was calculated from the time of 1 st response. Tumor genomic profile was analyzed using Tempus-xT ® assay (Chicago, IL), which includes targeted DNA sequencing (648 oncogenes) and whole transcriptome sequencing.RESULTSOf the 54 pts with RDD, ten were treated with cobimetinib and included in this study. The median follow-up was 16 months (m) [95% confidence interval (CI): 13-not reached (NR)] and most (n=8; 80%) were females. The median age at the time of treatment was 63 years (range: 36-74). Cobimetinib was used as first line therapy in four pts.Overall response rate was 70%, with 30% and 40% achieving complete (CR) and partial (PR) responses, respectively. One had stable disease (SD) and two had progressive disease (PD) (Table 1). The median progression-free-survival was 6.4 m (95%CI: 4.9-NR) and at 6 and 12 m, 67% and 50% of pts remained free from disease progression or death, respectively (Figure 1). The median duration of response was 7.6 m (95%CI: 3.1-NR). At the time of last follow-up, nine (90%) pts were alive. One pt died due to myelodysplastic syndrome with excessive blasts. She had multiple chemotherapy treatments before initiation of cobimetinib. Cobimetinib was discontinued in this pt due to grade 3 anemia and skin toxicity after 6 m of therapy and had SD as the best response.Median duration of treatment for the entire cohort was 6 m (range: 2-14). In the seven pts who responded, the median duration of treatment was 7 m (range: 2-14). Cobimetinib was discontinued in seven pts: disease progression (n=3; one disease progression after achieving PR and two PD while on therapy), grade 3 left ventricular systolic dysfunction (n=1), grade 3 diarrhea (n=1), grade 3 anemia (n=1), and grade 2 creatinine elevation (n=1). Five (50%) pts were started at a reduced dose of cobimetinib at the discretion of treating physician [20 mg (n=4) and 40mg, (n=1)]. Two pts were started at 60 mg and dose reduced to 20 mg after one cycle of treatment due to grade 2 skin toxicity in one and grade 2 skin toxicity and diarrhea in the other. Both pts achieved a PR but progressed after four and six cycles, respectively. One pt started at 40 mg and reduced to 20 mg due to grade 2 skin toxicity after two cycles achieving a PR. The response was sustained in this pt for at least 9 months, until the time of last follow-up (Table 1).Tissue molecular testing showed five pts with MAPK pathway alterations and all of them responded to therapy (CR=3 and PR=2). Of the other five pts who either did not have a MAPK pathway alteration (n=4) or had test failure (n=1), responses were observed in two (40%) pts, both PR (Table 1).CONCLUSIONOur study suggests that cobimetinib is an effective treatment in RDD, with responses observed in all pts having MAPK pathway alterations. Less than half of pts without a MAPK pathway alteration achieved a response. However, treatment discontinuations due to AEs were common despite dose reductions. Patients who were treated at low doses of cobimetinib also had remarkable clinical response. Further studies are needed in evaluating other MAPK pathway inhibitors with better toxicity profile to improve adherence and outcomes. [Display omitted] DisclosuresTobin: National Institutes of Health: Research Funding; Mayo Clinic Center for MS and Autoimmune Neurology: Research Funding; Mallinckrodt Pharmaceuticals: Research Funding. Bennani: Vividion: Other: Advisory Board; Kyowa Kirin: Other: Advisory Board; Daichii Sankyo Inc: Other: Advisory Board; Verastem: Other: Advisory Board; Purdue Pharma: Other: Advisory Board; Kymera: Other: Advisory Board. Vassallo: Pfizer: Research Funding; Bristol-Myers-Squibb: Research Funding; Sun Pharma.: Research Funding.

Multi-omic profiling of peritoneal metastases in gastric cancer identifies molecular subtypes and therapeutic vulnerabilities.

Peritoneal metastasis, a hallmark of incurable advanced gastric cancer (GC), presently has no curative therapy and its molecular features have not been examined extensively. Here we present a comprehensive multi-omic analysis of malignant ascitic fluid samples and their corresponding tumor cell lines from 98 patients, including whole-genome sequencing, RNA sequencing, DNA methylation and enhancer landscape. We identify a higher frequency of receptor tyrosine kinase and mitogen-activated protein kinase pathway alterations compared to primary GC; moreover, approximately half of the gene alterations are potentially treatable with targeted therapy. Our analyses also stratify ascites-disseminated GC into two distinct molecular subtypes: one displaying active super enhancers (SEs) at the ELF3, KLF5 and EHF loci, and a second subtype bearing transforming growth factor-β (TGF-β) pathway activation through SMAD3 SE activation and high expression of transcriptional enhancer factor TEF-1 (TEAD1). In the TGF-β subtype, inhibition of the TEAD pathway circumvents therapy resistance, suggesting a potential molecular-guided therapeutic strategy for this subtype of intractable GC.

Abstract C080: The combination of MEK and MDM2 inhibitors demonstrates promising antitumor efficacy in MAPK altered patient-derived thyroid and colorectal cancer models

Abstract Purpose: Genomic alterations in the mitogen activated protein kinase (MAPK) pathway are common in colorectal and thyroid cancer. However MEK inhibition alone has limited efficacy. We investigated the combinatorial antitumor efficacy of MEK (Selumetinib; AZD6244) and MDM2 inhibition (AMG232) in wild-type TP53 colorectal and thyroid cancers with MAPK alterations. Methods: One thyroid (BRAF mutated) and three colorectal cancer cell lines (KRAS mutated) were used to evaluate the anti-tumor effect of selumetinib combined with AMG232 in vitro. Sulforhodamine B and colony formation assays were utilized to determine the cytotoxicity of each single targeted agent and combination and to obtain the half maximal inhibitory concentration (IC50). The efficacy of the combination was evaluated in athymic mice with subcutaneously implanted patient-derived xenografts (PDX) of different histologic backgrounds (5 colorectal and 2 thyroid cancer) and with different genomic MAPK pathway alterations. Selumetinib (25 mg/kg in 6 models, and 15 mg/kg in 1 model) and AMG232 (15 mg/kg) were administered daily through oral route. Results: Selumetinib demonstrated synergistic activity with AMG232 across all four cell lines with combination indices ranging from 0.37 to 0.72. The antitumor efficacy was enhanced when combining the two agents in all seven PDX models and achieved statistical significance in six of seven PDX models compared to either single agent therapy alone. Treatment/Control ratio % ((median tumor volume of treatment group / control group) x 100) was obtained from each combination arm across in vivo experiments (31 % (range 12%-62%)) and it was greater than monotherapy alone (Selumetinib 51%; range 21%-76%, AMG232 77%; range 38%-100%). Conclusions: Our preclinical findings demonstrate enhanced anti-tumor efficacy when combining Selumetinib with AMG232, which supports further evaluation of MEK/MDM2 inhibition in patients with MAPK altered colorectal and thyroid cancer with wild-type TP53 status. Citation Format: Seyed Pairawan, Kurt Evans, Scott Kopetz, Argun Akcakanat, Ming Zhao, Coya Tapia, Naifa Busaidy, Ecaterina Dumbrava, Funda Meric-Bernstam. The combination of MEK and MDM2 inhibitors demonstrates promising antitumor efficacy in MAPK altered patient-derived thyroid and colorectal cancer models [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics; 2019 Oct 26-30; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2019;18(12 Suppl):Abstract nr C080. doi:10.1158/1535-7163.TARG-19-C080

Molecular Profiling Reclassifies Adult Astroblastoma into Known and Clinically Distinct Tumor Entities with Frequent Mitogen-Activated Protein Kinase Pathway Alterations.

Astroblastoma (ABM) is a rare glial brain tumor. Recurrent meningioma 1 (MN1) alterations have been recently identified in most pediatric cases. Adolescent and adult cases, however, remain molecularly poorly defined. We performed clinical and molecular characterization of a retrospective cohort of 14 adult and 1 adolescent ABM. Strikingly, we found that MN1 fusions are a rare event in this age group (1/15). Using methylation profiling and targeted sequencing, most cases were reclassified as either pleomorphic xanthoastrocytomas (PXA)-like or high-grade glioma (HGG)-like. PXA-like ABM show BRAF mutation (6/7 with V600E mutation and 1/7 with G466E mutation) and CD34 expression. Conversely, HGG-like ABM harbored specific alterations of diffuse midline glioma (2/5) or glioblastoma (GBM; 3/5). These latter patients showed an unfavorable clinical course with significantly shorter overall survival (p = .021). Mitogen-activated protein kinase pathway alterations (including FGFR fusion, BRAF and NF1 mutations) were present in 10 of 15 patients and overrepresented in the HGG-like group (3/5) compared with previously reported prevalence of these alterations in GBM and diffuse midline glioma. We suggest that gliomas with astroblastic features include a variety of molecularly sharply defined entities. Adult ABM harboring molecular features of PXA and HGG should be reclassified. Central nervous system high-grade neuroepithelial tumors with MN1 alterations and histology of ABM appear to be uncommon in adults. Astroblastic morphology in adults should thus prompt thorough molecular investigation aiming at a clear histomolecular diagnosis and identifying actionable drug targets, especially in the mitogen-activated protein kinase pathway. Astroblastoma (ABM) remains a poorly defined and controversial entity. Although meningioma 1 alterations seem to define a large subset of pediatric cases, adult cases remain molecularly poorly defined. This comprehensive molecular characterization of 1 adolescent and 14 adult ABM revealed that adult ABM histology comprises several molecularly defined entities, which explains clinical diversity and identifies actionable targets. Namely, pleomorphic xanthoastrocytoma-like ABM cases show a favorable prognosis whereas high-grade glioma (glioblastoma and diffuse midline gliome)-like ABM show significantly worse clinical courses. These results call for in-depth molecular analysis of adult gliomas with astroblastic features for diagnostic and therapeutic purposes.

Extracellular Signal-Regulated Kinase (ERK) Inhibitors in Oncology Clinical Trials

Abstract The mitogen-activated protein kinase (MAPK) pathway consists of the series of protein kinases RAS-RAF-MEK-Extracellular signal-regulated kinase (ERK), and its function is important to cell proliferation, differentiation, motility, and survival. Certain mutations in the pathway, such as KRAS or BRAF V600 mutations are associated with cancer. Inhibitors of this pathway, including some MEK and BRAF inhibitors, are already being used in the clinic, but a variety of selective ERK inhibitors are still being tested in clinical studies. To date, common adverse events associated with ERK inhibitors include diarrhea, nausea, fatigue, and rash. ERK inhibitors have demonstrated preliminary antitumor activity and may be most effective against cancers with RAS, RAF, or MAPK pathway alterations. This review discusses the MAPK pathway, the biological rationale for ERK inhibitors, and clinical trials involving ERK inhibitors.

Low-Grade Serous Ovarian Cancer: Current Treatment Paradigms and Future Directions.

Low-grade serous ovarian cancer (LGSOC) is a rare subtype of ovarian cancer, accounting for approximately 10% of cases of serous ovarian cancer. Patients typically present at a younger age have a protracted clinical course with survival for those with recurrent disease nearing 10years, and have a high prevalence of somatic (tumor-specific) mutations affecting the mitogen-activated protein kinase (MAPK) pathway. Initial treatment of patients with stage IC-IV disease is similar to that of high-grade serous ovarian cancer with surgery and platinum/taxane-based chemotherapy. Selected patients may benefit from hormonal maintenance therapy following chemotherapy, in particular those with evidence of residual disease at completion of therapy. In the recurrent setting, the highest response rates to chemotherapy have been noted in those patients receiving chemotherapy in combination with bevacizumab. While hormonal therapies may offer disease stabilization with relatively low toxicity, objective response rates remain low. The use of targeted therapies such as MEK inhibitors remains an active area of investigation and those patients with MAPK pathway alterations may derive the greatest benefit from these agents.

A phase I study of LXH254 in patients (pts) with advanced solid tumors harboring MAPK pathway alterations.

2586Background: CRAF is a key mediator of oncogenic mitogen-activated protein kinase (MAPK) pathway reactivation following MEK or BRAF inhibition. LXH254 is a BRAF and CRAF inhibitor with antitumor...

Initiative for Molecular Profiling and Advanced Cancer Therapy (IMPACT): An MD Anderson Precision Medicine Study.

Genomic profiling is increasingly used in the management of cancer. We have previously reported preliminary results of our precision medicine program. Here, we present response and survival outcomes for 637 additional patients who were referred for phase I trials and were treated with matched targeted therapy (MTT) when available. Patients with advanced cancer who underwent tumor genomic analyses were treated with MTT when available. Overall, 1,179 (82.1%) of 1,436 patients had one or more alterations (median age, 59.7 years; men, 41.2%); 637 had one or more actionable aberrations and were treated with MTT (n = 390) or non-MTT (n = 247). Patients who were treated with MTT had higher rates of complete and partial response (11% v 5%; P = .0099), longer failure-free survival (FFS; 3.4 v 2.9 months; P = .0015), and longer overall survival (OS; 8.4 v 7.3 months; P = .041) than did unmatched patients. Two-month landmark analyses showed that, for MTT patients, FFS for responders versus nonresponders was 7.6 versus 4.3 months (P < .001) and OS was 23.4 versus 8.5 months (P < .001), whereas for non-MTT patients (responders v nonresponders), FFS was 6.6 versus 4.1 months (P = .001) and OS was 15.2 versus 7.5 months (P = .43). Patients with phosphatidylinositol 3-kinase (PI3K) and mitogen-activated protein kinase pathway alterations matched to PI3K/Akt/mammalian target of rapamycin axis inhibitors alone demonstrated outcomes comparable to unmatched patients. Our results support the use of genomic matching. Subset analyses indicate that matching patients who harbor a PI3K and mitogen-activated protein kinase pathway alteration to only a PI3K pathway inhibitor does not improve outcome. We have initiated IMPACT2, a randomized trial to compare treatment with and without genomic selection.

MAP4K4 is a novel MAPK/ERK pathway regulator required for lung adenocarcinoma maintenance.

About 76% of patients with lung adenocarcinoma harbor activating mutations in the receptor tyrosine kinase (RTK)/RAS/RAF pathways, leading to aberrant activation of the mitogen‐activated protein kinase (MAPK) pathways particularly the MAPK/ERK pathway. However, many lung adenocarcinomas lacking these genomic mutations also display significant MAPK pathway activation, suggesting that additional MAPK pathway alterations remain undetected. This study has identified serine/threonine kinase mitogen‐activated protein 4 kinase 4 (MAP4K4) as a novel positive regulator of MAPK/ERK signaling in lung adenocarcinoma. The results showed that MAP4K4 was drastically elevated in lung adenocarcinoma independently of KRAS or EGFR mutation status. Knockdown of MAP4K4 inhibited proliferation, anchorage‐independent growth and migration of lung adenocarcinoma cells, and also inhibited human lung adenocarcinoma xenograft growth and metastasis. Mechanistically, we found that MAP4K4 activated ERK through inhibiting protein phosphatase 2 activity. Our results further showed that downregulation of MAP4K4 prevented ERK reactivation in EGFR inhibitor erlotinib‐treated lung adenocarcinoma cells. Together, our findings identify MAP4K4 as a novel MAPK/ERK pathway regulator in lung adenocarcinoma that is required for lung adenocarcinoma maintenance.

Recurrent somatic alterations of FGFR1 and NTRK2 in pilocytic astrocytoma

Pilocytic astrocytoma, the most common childhood brain tumor, is typically associated with mitogen-activated protein kinase (MAPK) pathway alterations. Surgically inaccessible midline tumors are therapeutically challenging, showing sustained tendency for progression and often becoming a chronic disease with substantial morbidities. Here we describe whole-genome sequencing of 96 pilocytic astrocytomas, with matched RNA sequencing (n = 73), conducted by the International Cancer Genome Consortium (ICGC) PedBrain Tumor Project. We identified recurrent activating mutations in FGFR1 and PTPN11 and new NTRK2 fusion genes in non-cerebellar tumors. New BRAF-activating changes were also observed. MAPK pathway alterations affected all tumors analyzed, with no other significant mutations identified, indicating that pilocytic astrocytoma is predominantly a single-pathway disease. Notably, we identified the same FGFR1 mutations in a subset of H3F3A-mutated pediatric glioblastoma with additional alterations in the NF1 gene. Our findings thus identify new potential therapeutic targets in distinct subsets of pilocytic astrocytoma and childhood glioblastoma.

Biotransformed blueberry juice protects neurons from hydrogen peroxide-induced oxidative stress and mitogen-activated protein kinase pathway alterations

A growing body of evidence supports the therapeutic effects of blueberry in neurodegenerative disorders. Biotransformation of blueberry juice by Serratia vaccinii bacteria increases its phenolic content and antioxidant activity. In neuronal cell culture, biotransformed blueberry juice (BJ) significantly increased the activity of antioxidant enzymes, namely catalase and superoxide dismutase. Moreover, BJ protected neurons against H2O2-induced cell death in a dose-dependent manner. This associated with the upregulation of mitogen-activated protein kinase (MAPK) family enzymes p38 and c-Jun N-terminal kinase (JNK) activation, as well as with the protection of extracellular signal-regulated kinase (ERK1/2) and MAPK/ERK kinase (MEK1/2) activity loss induced by H2O2. The present studies demonstrate that BJ can protect neurons against oxidative stress possibly by increasing antioxidant enzyme activities and activating p38- and JNK-dependent survival pathways while blocking MEK1/2- and ERK1/2-mediated cell death. Thus, BJ may represent a novel approach to prevent and to treat neurodegenerative disorders, and it may represent a source of novel therapeutic agents against these diseases.