Safety of BRAF+MEK Inhibitor Combinations: Severe Adverse Event Evaluation

New Adverse Drug Reaction Signals from 2017 to 2021-Genuine Alerts or False Alarms?

Spontaneous adverse events reporting systems are used internationally to flag new or unexpected adverse drug reactions (ADRs). Disproportionality analysis is a recognised technique, but false alarms may arise. We aimed to determine whether these new ADR signals had subsequently been followed-up with detailed hypothesis-testing studies. We searched PubMed to identify published studies (years 2017-2021) where the authors reported findings of new ADR signals from disproportionality analyses. We used PubMed and forward citation tracking (Google Scholar) to identify any subsequent confirmatory studies of these ADR signals. We screened 414 titles and abstracts and checked the full-text articles of 57 studies. We found signals for 56 suspected new ADRs from 24 drugs. Google Scholar showed that the ADR studies had been cited a median of seven times (range 0-61). However, none of the suspected new ADRs had undergone detailed evaluation in the citing literature. Similarly, our PubMed search did not find any confirmation studies for the 56 suspected new ADRs. Although many suspected new ADR signals have been identified through disproportionality analysis, most signals have not been further verified as being either genuine ADRs or false alarms. Researchers must focus on follow-up studies for these new signals.

Case report: Parsonage-turner syndrome in a melanoma patient treated by BRAF/MEK inhibitors after immune checkpoint inhibitors

Introduction

Combination molecular BRAF/MEK inhibitors targeted therapy has been shown to improve overall survival in patients with BRAF V600 mutated unresectable or metastatic melanoma. Most patients treated with BRAF/MEK inhibitors will experience adverse events but neurological adverse events (nAEs) remain rare.

Case report

A 42-year-old woman diagnosed with metastatic melanoma presented with an intense pain in the left shoulder 7 days after the beginning of encorafenib/binimetinib after immune checkpoint inhibitors (ICI) combination. No other triggering factors were identified. Electromyogram performed one month after the pain onset revealed a left brachial plexopathy suggestive of a Parsonage-Turner syndrome. The weakness slowly improved with intensive rehabilitation and targeted therapies were continued.

Conclusion

We report the first case of Parsonage-Turner syndrome in a melanoma patient treated with encorafenib/binimetinib following checkpoint inhibitors combination.We cannot rule out the implication of ICI in the development of this syndrome but the rapid onset of the symptoms after the beginning of targeted therapies makes their involvment more likely.Given the increased use of BRAF/MEK inhibitors in managing of stage III and IV melanoma, as well as the development in stage II, clinicians should be aware of this potential side effect.

Demyelinating polyradiculoneuropathy during dabrafenib and trametinib treatment for metastatic melanoma: A case report

BACKGROUND

Melanoma is an aggressive malignancy, historically characterized with a poor prognosis and few treatment options. The advent of target therapy with BRAF and MEK inhibitors, as well as immunotherapy, changed this scenario and improved the prognosis of patients with BRAF V600E mutation. These therapies are generally well tolerated. Neurological toxicities, especially polyradiculopathy, are very rare with BRAF inhibitors and MEK inhibitors although some cases have been described in recent years, regardless of the type of target therapies combination used.

CASE REPORT

We report the case of a patient with BRAF V600E-mutated metastatic melanoma treated with dabrafenib and trametinib who has developed a demyelinating polyradiculoneuropathy.

CONCLUSION

This case, once more, should draw our attention to the possibility of rare, but potentially serious side effects, even in the case of generally well-tolerated treatments. Especially in the presence of side effects, it is important a close relationship between clinicians and patients for the management of adverse events and the choice of the best treatment strategy.

Neuropsychiatric adverse drug reactions with oral tyrosine kinase inhibitors in metastatic colorectal cancer: an analysis from the FDA Adverse Event Reporting System

Introduction

New oral tyrosine kinase inhibitors (TKIs) are approved for metastatic colorectal cancer (mCRC). The aim of this study was to assess the neuropsychiatric adverse drug reactions (ADRs) of these drugs reported in the FDA Adverse Event Reporting System (FAERS) database.

Methods

All reports with regorafenib (REG) and encorafenib (ENC) as the primary suspect, and reported in the FAERS between 2012 and 2022, were collected. A descriptive and disproportionality analyses were conducted.

Results

Out of 4,984 cases, 1,357 (30.2%) reported at least one neuropsychiatric ADR. New potential signals for REG included neuropathy peripheral (n = 265; reporting odds ratio, ROR = 19.48, 95% confidence interval, CI 95% = 17.52-22.47; information component, IC = 2.89, IC025-IC075 = 2.77-3.02), hyperesthesia (n = 18; ROR = 12.56, CI 95% = 7.90-19.96; IC = 2.25, IC025-IC075 = 1.79-2.72), taste disorder (n = 41; ROR = 9.91, CI 95% = 7.29-13.49; IC = 2.18, IC025-IC075 = 1.88-2.49), poor quality sleep (n = 18; ROR = 6.56, CI 95% = 4.13-10.42; IC = 1.74, IC025-IC075 = 1.27-2.20), altered state of consciousness (n = 15; ROR = 5.50, CI 95% = 3.31-9.14; IC = 1.57, IC025-IC075 = 1.06-2.07), depressed mood (n = 13; ROR = 1.85, CI 95% = 1.07-3.19; IC = 0.58, IC025-IC075 = 0.04-1.13) and insomnia (n = 63; ROR = 1.48, CI 95% = 1.15-1.89; IC = 0.38, IC025-IC075 = 0.13-0.63). For ENC comprised depressed mood (n = 4; ROR = 5.75, CI 95% = 2.15-15.39; IC = 1.74, IC025-IC075 = 0.76-2.73) and cognitive disorders (n = 3; ROR = 4.71, CI 95% = 1.51-14.66; IC = 1.54, IC025-IC075 = 0.41-2.68).

Discussion

This study identified new unknown potential neuropsychiatric ADRs. Further investigations are required to better define the neurotoxicity of TKIs in mCRC patients.

The Impact of Drug-Drug Interactions on the Toxicity Profile of Combined Treatment with BRAF and MEK Inhibitors in Patients with BRAF-Mutated Metastatic Melanoma

BACKGROUND

BRAF and MEK inhibition is a successful strategy in managing BRAF-mutant melanoma, even if the treatment-related toxicity is substantial. We analyzed the role of drug-drug interactions (DDI) on the toxicity profile of anti-BRAF/anti-MEK therapy.

METHODS

In this multicenter, observational, and retrospective study, DDIs were assessed using Drug-PIN software (V 2/23). The association between the Drug-PIN continuous score or the Drug-PIN traffic light and the occurrence of treatment-related toxicities and oncological outcomes was evaluated.

RESULTS

In total, 177 patients with advanced BRAF-mutated melanoma undergoing BRAF/MEK targeted therapy were included. All grade toxicity was registered in 79% of patients. Cardiovascular toxicities occurred in 31 patients (17.5%). Further, 94 (55.9%) patients had comorbidities requiring specific pharmacological treatments. The median Drug-PIN score significantly increased when the target combination was added to the patient's home therapy (p-value < 0.0001). Cardiovascular toxicity was significantly associated with the Drug-PIN score (p-value = 0.048). The Drug-PIN traffic light (p = 0.00821) and the Drug-PIN score (p = 0.0291) were seen to be significant predictors of cardiotoxicity. Patients with low-grade vs. high-grade interactions showed a better prognosis regarding overall survival (OS) (p = 0.0045) and progression-free survival (PFS) (p = 0.012). The survival analysis of the subgroup of patients with cardiological toxicity demonstrated that patients with low-grade vs. high-grade DDIs had better outcomes in terms of OS (p = 0.0012) and a trend toward significance in PFS (p = 0.068).

CONCLUSIONS

DDIs emerged as a critical issue for the risk of treatment-related cardiovascular toxicity. Our findings support the utility of DDI assessment in melanoma patients treated with BRAF/MEK inhibitors.

Renal Disorders with Oral Tyrosine Kinase Inhibitors in Metastatic Colorectal Cancer: An Analysis from the FDA Adverse Event Reporting System Database

BACKGROUND

this study assessed the nephrotoxicity of regorafenib (REG) and encorafenib (ENC) in metastatic colorectal cancer (mCRC) through an analysis of reports from the US Food and Drug Administration's Adverse Event Reporting System (FAERS) database.

METHODS

descriptive and disproportional analyses were performed for all reports using ENC and REG as the primary suspect.

RESULTS

A total of 379 reports had at least one renal adverse drug reaction (ADR), and these ADRs were mainly related to REG (93.1%). Potential safety signals for REG included chromaturia (n = 44; ROR = 12.00, CI 95% = 8.92-16.16; IC = 2.36, IC025-IC075 = 2.06-2.66), hydronephrosis (10; 8.70, 4.67-16.19; 1.85, 1.23-2.47), nephrotic syndrome (7; 5.73, 2.73-12.03; 1.47, 0.73-2.21), renal impairment (53; 4.16, 3.17-5.45; 1.39, 1.12-1.66), dysuria (19; 3.06, 1.95-4.81; 1.06, 0.61-1.52), renal failure (38; 1.66, 1.20-2.28; 0.49, 0.17-0.81), and acute kidney injury (AKI) (43; 1.46, 1.08-1.97; 0.37, 0.07-0.67). For ENC, consistent disproportionalities were observed for AKI (n = 11; ROR = 3.79, CI 95% = 2.09-6.90; IC = 1.32, IC025-IC075 = 0.72-1.91) and dysuria (4; 6.50, 2.43-17.39; 1.86, 0.88-2.85).

CONCLUSIONS

these findings highlight some not extensively reported renal ADRs that require further investigations to better characterize the safety profiles of REG and ENC in patients with mCRC.

Guillain-Barre Syndrome Secondary to the Use of Dabrafenib and Trametinib for the Treatment of Advanced Thyroid Carcinoma

BRAF V600E mutation in thyroid malignancies is associated with an aggressive phenotype with more rapid tumor growth and higher mortality. V600E is a driver mutation in the BRAF proto-oncogene, where valine (V) is substituted by glutamic acid (E) at amino acid 600. New chemotherapeutic agents targeting the mitogen-activated protein kinase (MAPK) pathway, including direct BRAF inhibitors, have become available and are increasingly used in various advanced thyroid malignancies. These agents are associated with various rare neurological adverse effects. We present a case of Guillain-Barre syndrome (GBS) secondary to dabrafenib and trametinib therapy for the management of anaplastic thyroid carcinoma. A few cases of GBS have been reported previously with the use of these agents in the treatment of melanoma. To our knowledge, this is the first case of GBS with the use of dabrafenib and trametinib for advanced thyroid malignancy. The knowledge of this rare, potentially life-threatening condition is important for clinicians to know, given the increased use of these agents in managing advanced thyroid malignancies.

COLUMBUS 5-Year Update: A Randomized, Open-Label, Phase III Trial of Encorafenib Plus Binimetinib Versus Vemurafenib or Encorafenib in Patients With BRAF V600-Mutant Melanoma

PURPOSE

Combination treatment with BRAF and MEK inhibitors has demonstrated benefits on progression-free survival (PFS) and overall survival (OS) and is a standard of care for the treatment of advanced BRAF V600-mutant melanoma. Here, we report the 5-year update from the COLUMBUS trial (ClinicalTrials.gov identifier: NCT01909453).

METHODS

Patients with locally advanced unresectable or metastatic BRAF V600-mutant melanoma, untreated or progressed after first-line immunotherapy, were randomly assigned 1:1:1 to encorafenib 450 mg once daily plus binimetinib 45 mg twice daily, vemurafenib 960 mg twice daily, or encorafenib 300 mg once daily. An updated analysis was conducted 65 months after the last patient was randomly assigned.

RESULTS

Five hundred seventy-seven patients were randomly assigned: 192 to encorafenib plus binimetinib, 191 to vemurafenib, and 194 to encorafenib. The 5-year PFS and OS rates with encorafenib plus binimetinib were 23% and 35% overall and 31% and 45% in those with normal lactate dehydrogenase levels, respectively. In comparison, the 5-year PFS and OS rates with vemurafenib were 10% and 21% overall and 12% and 28% in those with normal lactate dehydrogenase levels, respectively. The median duration of response with encorafenib plus binimetinib was 18.6 months, with disease control achieved in 92.2% of patients. In comparison, the median duration of response with vemurafenib was 12.3 months, with disease control achieved in 81.2% of patients. Long-term follow-up showed no new safety concerns, and results were consistent with the known tolerability profile of encorafenib plus binimetinib. Interactive visualization of the data presented in this article is available at COLUMBUS dashboard.

CONCLUSION

In this 5-year update of part 1 of the COLUMBUS trial, encorafenib plus binimetinib treatment demonstrated continued long-term benefits and a consistent safety profile in patients with BRAF V600-mutant melanoma.

Peripheral neuropathies after BRAF and/or MEK inhibitors treatment: a pharmacovigilance study

Reports suggested the potential occurrence of peripheral neuropathies (PN) in patients treated with BRAF (BRAFi) and/or MEK inhibitors (MEKi) for BRAF-activated tumours. We aimed to better characterize these PN. We queried the French pharmacovigilance database for all cases of PN attributed to BRAFi and/or MEKi. Fifteen patients were identified. Two main clinical PN phenotypes were seen. Six patients presented a length-dependent, axonal polyneuropathy: symptoms were mostly sensory and affecting the lower limbs; management and outcome were variable. Nine patients developed a demyelinating polyradiculoneuropathy: symptoms affected the four limbs and included hypoesthesia, weakness, and ataxia; cranial nerves were involved in four cases; most patients received intravenous immunoglobulins or glucocorticoids, with variable outcome; one patient was rechallenged with a different BRAFi/MEKi combination with a rapid symptoms relapse. In conclusion, patients under BRAFi/MEKi therapy may develop treatment-induced PN. Two main phenotypes can occur: a symmetric, axonal, length-dependent polyneuropathy, and a demyelinating polyradiculoneuropathy.

Truth or dare: switching BRAF/MEK inhibitors after acute interstitial nephritis in a patient with metastatic melanoma - A case report and review of the literature

INTRODUCTION

The introduction of BRAF/MEK inhibitors has significantly improved overall survival of patients with BRAF V600-mutant advanced or metastatic melanoma. Most patients treated with BRAF/MEK inhibitors will experience adverse events during the course of their treatment. Kidney impairment, however, was rarely reported in the pivotal trials. To date, there are only three cases of biopsy-proven acute interstitial nephritis associated with dabrafenib and trametinib reported in the literature.

CASE REPORT

A 50-year-old man diagnosed with metastatic melanoma was hospitalized in August 2021, 5 months after treatment initiation with dabrafenib and trametinib. He presented with acute kidney injury, with serum creatinine of 3.34 mg/dL and eGFR of 20.3 mL/min/m². Kidney biopsy revealed acute interstitial nephritis.

MANAGEMENT & OUTCOME

He was treated with methylprednisolone 16 mg qd, and both dabrafenib and trametinib were permanently discontinued, with recuperation of his kidney function. Another BRAF/MEK inhibitor combination, encorafenib and binimetinib, was introduced, with preserved kidney function and excellent disease control.

DISCUSSION

We report the first case of biopsy-proven interstitial nephritis in a patient treated with dabrafenib and trametinib, with successful introduction of another BRAF/MEK inhibitor combination. Although rare, clinicians should be aware of the risk of renal adverse events associated with BRAF/MEK inhibitors. Renal biopsy is mandatory in the absence of a clear explanation or rapid recovery of renal failure. In case of proven interstitial nephritis, corticosteroids should be initiated. Switching to another BRAF/MEK inhibitor combination can be considered for patients with complete recovery of renal function and limited treatment options.

Dyslipidemia in Children Treated with a BRAF Inhibitor for Low-Grade Gliomas: A New Side Effect?

BRAF inhibitors, in recent years, have played a central role in the disease control of unresectable BRAF-mutated pediatric low-grade gliomas (LGGs). The aim of the study was to investigate the acute and long-term effects of vemurafenib on the lipid metabolism in children treated for an LGG. In our cohort, children treated with vemurafenib (n = 6) exhibited alterations in lipid metabolism a few weeks after starting, as was demonstrated after 1 month (n = 4) by the high plasma levels of the total cholesterol (TC = 221.5 ± 42.1 mg/dL), triglycerides (TG = 107.8 ± 44.4 mg/dL), and low-density lipoprotein (LDL = 139.5 ± 51.5 mg/dL). Despite dietary recommendations, the dyslipidemia persisted over time. The mean lipid levels of the TC (222.3 ± 34.7 mg/dL), TG (134.8 ± 83.6 mg/dL), and LDL (139.8 ± 46.9 mg/dL) were confirmed abnormal at the last follow-up (45 ± 27 months, n = 6). Vemurafenib could be associated with an increased risk of dyslipidemia. An accurate screening strategy in new clinical trials, and a multidisciplinary team, are required for the optimal management of unexpected adverse events, including dyslipidemia.

Nephrotoxicity in cancer treatment: An update

It has been estimated that nearly 80% of anticancer drug-treated patients receive potentially nephrotoxic drugs, while the kidneys play a central role in the excretion of anticancer drugs. Nephrotoxicity has long been a serious complication that hampers the effectiveness of cancer treatment and continues to influence both mortality and length of hospitalization among cancer patients exposed to either conventional cytotoxic agents or targeted therapies. Kidney injury arising from anticancer drugs tends to be associated with preexisting comorbidities, advanced cancer stage, and the use of concomitant non-chemotherapeutic nephrotoxic drugs. Despite the prevalence and impact of kidney injury on therapeutic outcomes, the field is sorely lacking in an understanding of the mechanisms driving cancer drug-induced renal pathophysiology, resulting in quite limited and largely ineffective management of anticancer drug-induced nephrotoxicity. Consequently, there is a clear imperative for understanding the basis for nephrotoxic manifestations of anticancer agents for the successful management of kidney injury by these drugs. This article provides an overview of current preclinical research on the nephrotoxicity of cancer treatments and highlights prospective approaches to mitigate cancer therapy-related renal toxicity.

Melanoma: An update on systemic therapies

Despite advances in early detection as described in part 1 of this continuing medical education series, melanoma continues to be a large contributor to cutaneous cancer-related mortality. In a subset of patients with unresectable or metastatic disease, surgical clearance is often not possible; therefore, systemic and local therapies are considered. The second article in this series provides dermatologists with an up-to-date working knowledge of the treatment options that may be prescribed by oncologists for patients with unresectable stage III, stage IV, and recurrent melanoma.

Melanoma Management during the COVID-19 Pandemic Emergency: A Literature Review and Single-Center Experience

Simple Summary

COVID-19 is a highly contagious infection caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In March 2020, the World Health Organization (WHO) declared that COVID-19 had become a pandemic; since then, several elective clinical and surgical activities have been postponed to reduce the risk of nosocomial infection. This has influenced the diagnosis and management of many diseases, including melanoma. The aim of our literature review was to evaluate whether the management of melanoma has been changed by the outbreak of COVID-19, and if so, what the consequences of these changes are. The main topics in this literature review are the screening of suspicious lesions, diagnosis of primary melanoma, and the management of early-stage and advanced melanomas in the COVID-19 era. We also reported the experience of our dermatological clinic in Turin, one of the most affected areas in Italy.

Abstract

Background: The current COVID-19 pandemic has influenced the modus operandi of all fields of medicine, significantly impacting patients with oncological diseases and multiple comorbidities. Thus, in recent months, the establishment of melanoma management during the emergency has become a major area of interest. In addition to original articles, case reports and specific guidelines for the period have been developed. Purpose: This article aims to evaluate whether melanoma management has been changed by the outbreak of COVID-19, and if so, what the consequences are. We summarized the main issues concerning the screening of suspicious lesions, the diagnosis of primary melanoma, and the management of early-stage and advanced melanomas during the pandemic. Additionally, we report on the experience of our dermatological clinic in northern Italy. Methods: We performed a literature review evaluating articles on melanomas and COVID-19 published in the last two years on PubMed, as well as considering publications by major healthcare organizations. Concerning oncological practice in our center, we collected data on surgical and therapeutic procedures in patients with a melanoma performed during the first months of the pandemic. Conclusions: During the emergency period, the evaluation of suspicious skin lesions was ensured as much as possible. However, the reduced level of access to medical care led to a documented delay in the diagnosis of new melanomas. When detected, the management of early-stage and advanced melanomas was fully guaranteed, whereas the follow-up visits of disease-free patients have been postponed or replaced with a teleconsultation when possible.

The Status of Adjuvant and Neoadjuvant Melanoma Therapy, New Developments and Upcoming Challenges

The global incidence of malignant melanoma, the leading cause of skin cancer death, has steadily increased in recent years. Surgical excision is the treatment of choice for early-stage melanoma. However, 40-60% of patients with high-risk melanoma or with nodal involvement eventually experience loco-regional relapse or tumor progression. Adjuvant therapy aims to reduce the rate of recurrence in radically operated high-risk patients with melanoma and thus improves survival. Interferon-α has long been the only approved drug for adjuvant melanoma therapy, despite an unclear survival benefit. The landmark success of immune-checkpoint inhibitors and BRAF/MEK-directed targeted therapies in the treatment of patients with stage IV melanoma led to the initiation of clinical trials in the adjuvant setting. These trials demonstrated the efficacy of immune-checkpoint inhibitors and targeted therapies for the adjuvant treatment of high-risk patients with melanoma, as shown both by an increase in recurrence-free survival and the emergence of long-term survivors, finally resulting in the approval of the cytotoxic T-lymphocyte antigen 4 inhibitor ipilimumab, PD1 inhibitors (nivolumab, pembrolizumab), and BRAF/MEK inhibitors for adjuvant melanoma therapy. This review aims to delineate the advances in adjuvant melanoma therapy, issuing particularly recent results from clinical trials. Moreover, we also discuss pending issues and future challenges, which comprise the adequate selection of adjuvant regimens for patient subgroups and the identification of markers likely to predict the individual response to adjuvant treatments. Last, we outline the role of emerging neoadjuvant approaches, which may complement adjuvant strategies and are currently investigated in clinical trials.

A Validated LC-MS/MS Assay for the Simultaneous Quantification of the FDA-Approved Anticancer Mixture (Encorafenib and Binimetinib): Metabolic Stability Estimation

The concurrent use of oral encorafenib (Braftovi, ENF) and binimetinib (Mektovi, BNB) is a combination anticancer therapy approved by the United States Food and Drug Administration (USFDA) for patients with BRAFV600E/V600K mutations suffering from metastatic or unresectable melanoma. Metabolism is considered one of the main pathways of drug elimination from the body (responsible for elimination of about 75% of known drugs), it is important to understand and study drug metabolic stability. Metabolically unstable compounds are not good as they required repetitive dosages during therapy, while very stable drugs may result in increasing the risk of adverse drug reactions. Metabolic stability of compounds could be examined using in vitro or in silico experiments. First, in silico metabolic vulnerability for ENF and BNB was investigated using the StarDrop WhichP450 module to confirm the lability of the drugs under study to liver metabolism. Second, we established an LC-MS/MS method for the simultaneous quantification of ENF and BNB applied to metabolic stability assessment. Third, in silico toxicity assessment of ENF and BNB was performed using the StarDrop DEREK module. Chromatographic separation of ENF, BNB, and avitinib (an internal standard) was achieved using an isocratic mobile phase on a Hypersil BDS C18 column. The linear range for ENF and BNB in the human liver microsome (HLM) matrix was 5-500 ng/mL (R2 ≥ 0.999). The metabolic stabilities were calculated using intrinsic clearance and in vitro half-life. Furthermore, ENF and BNB did not significantly influence each other's metabolic stability or metabolic disposition when used concurrently. These results indicate that ENF and BNB will slowly bioaccumulate after multiple doses.

Radiomics Biomarkers Correlate with CD8 Expression and Predict Immune Signatures in Melanoma Patients

Treatment for metastatic melanoma includes targeted and/or immunotherapy. Although many patients respond, only a subset has complete response. As late-stage patients often have multiple tumors in difficult access sites, non-invasive techniques are necessary for the development of predictive/prognostic biomarkers. PET/CT scans from 52 patients with stage III/IV melanoma were assessed and CT image parameters were evaluated as prognostic biomarkers. Analysis indicated patients with high standard deviation or high mean of positive pixels (MPP) had worse progression-free survival (P = 0.00047 and P = 0.0014, respectively) and worse overall survival (P = 0.0223 and P = 0.0465, respectively). Whole-exome sequencing showed high MPP was associated with BRAF mutation status (P = 0.0389). RNA-sequencing indicated patients with immune "cold" signatures had worse survival, which was associated with CT biomarker, MPP4 (P = 0.0284). Multiplex immunofluorescence confirmed a correlation between CD8 expression and image biomarkers (P = 0.0028). IMPLICATIONS: CT parameters have the potential to be cost-effective biomarkers of survival in melanoma, and reflect the tumor immune-microenvironment. VISUAL OVERVIEW: http://mcr.aacrjournals.org/content/molcanres/19/6/950/F1.large.jpg.

Protein Arginine Methyltransferase 5 (PRMT5) and the ERK1/2 & PI3K Pathways: A Case for PRMT5 Inhibition and Combination Therapies in Cancer

The ERK1/2 (RAS, RAF, MEK, ERK) and PI3K (PI3K, AKT, mTOR, PTEN) pathways are the chief signaling pathways for cellular proliferation, survival, and differentiation. Overactivation and hyperphosphorylation of the ERK1/2 & PI3K pathways is frequently observed in cancer and is associated with poor patient prognosis. While it is well known that genetic alterations lead to the dysregulation of the ERK1/2 & PI3K pathways, increasing evidence showcase that epigenetic alterations also play a major role in the regulation of the ERK1/2 & PI3K pathways. Protein Arginine Methyltransferase 5 (PRMT5) is a posttranslational modifier for multiple cellular processes, which is currently being tested as a therapeutic target for cancer. PRMT5 has been shown to be overexpressed in many types of cancers, as well as negatively correlated with patient survival. Numerous studies are indicating that as a posttranslational modifier, PRMT5 is extensively involved in regulating the ERK1/2 & PI3K pathways. In addition, a large number of in vitro and in vivo studies are demonstrating that PRMT5 inhibition, as well as PRMT5 and ERK1/2 & PI3K combination therapies, show significant therapeutic effects in many cancer types. In this review, we explore the vast interactions that PRMT5 has with the ERK1/2 & PI3K pathways, and we make the case for further testing of PRMT5 inhibition, as well as PRMT5 and ERK1/2 & PI3K combination therapies, for the treatment of cancer.