A phase 1 dose-escalation and expansion study of binimetinib (MEK162), a potent and selective oral MEK1/2 inhibitor

Past, Present, and Future Therapeutic Strategies for NF-1-Associated Tumors

PURPOSE OF REVIEW

Neurofibromatosis type 1 (NF-1) is a cancer predisposition syndrome caused by mutations in the NF1 tumor suppressor gene that encodes the neurofibromin protein, which functions as a negative regulator of Ras signaling. We review the past, current, and future state of therapeutic strategies for tumors associated with NF-1.

RECENT FINDINGS

Therapeutic efforts for NF-1-associated tumors have centered around inhibiting Ras output, leading to the clinical success of downstream MEK inhibition for plexiform neurofibromas and low-grade gliomas. However, MEK inhibition and similar molecular monotherapy approaches that block Ras signaling do not work for all patients and show limited efficacy for more aggressive cancers such as malignant peripheral nerve sheath tumors and high-grade gliomas, motivating novel treatment approaches. We highlight the current therapeutic landscape for NF-1-associated tumors, broadly categorizing treatment into past strategies for serial Ras pathway blockade, current approaches targeting parallel oncogenic and tumor suppressor pathways, and future avenues of investigation leveraging biologic and technical innovations in immunotherapy, pharmacology, and gene delivery.

Phase I/II Study of Combined BCL-xL and MEK Inhibition with Navitoclax and Trametinib in KRAS or NRAS Mutant Advanced Solid Tumors

PURPOSE

MEK inhibitors (MEKi) lack monotherapy efficacy in most RAS-mutant cancers. BCL-xL is an anti-apoptotic protein identified by a synthetic lethal shRNA screen as a key suppressor of apoptotic response to MEKi.

PATIENTS AND METHODS

We conducted a dose escalation study (NCT02079740) of the BCL-xL inhibitor navitoclax and MEKi trametinib in patients with RAS-mutant tumors with expansion cohorts for: pancreatic, gynecologic (GYN), non-small cell lung cancer (NSCLC), and other cancers harboring KRAS/NRAS mutations. Paired pretreatment and day 15 tumor biopsies and serial cell-free (cf)DNA were analyzed.

RESULTS

A total of 91 patients initiated treatment, with 38 in dose escalation. Fifty-eight percent had ≥3 prior therapies. A total of 15 patients (17%) had colorectal cancer, 19 (11%) pancreatic, 15 (17%) NSCLC, and 32 (35%) GYN cancers. The recommended phase II dose (RP2D) was established as trametinib 2 mg daily days 1 to 14 and navitoclax 250 mg daily days 1 to 28 of each cycle. Most common adverse events included diarrhea, thrombocytopenia, increased AST/ALT, and acneiform rash. At RP2D, 8 of 49 (16%) evaluable patients achieved partial response (PR). Disease-specific differences in efficacy were noted. In patients with GYN at the RP2D, 7 of 21 (33%) achieved a PR and median duration of response 8.2 months. No PRs occurred in patients with colorectal cancer, NSCLC, or pancreatic cancer. MAPK pathway inhibition was observed in on-treatment tumor biopsies. Reductions in KRAS/NRAS mutation levels in cfDNA correlated with clinical benefit.

CONCLUSIONS

Navitoclax in combination with trametinib was tolerable. Durable clinical responses were observed in patients with RAS-mutant GYN cancers, warranting further evaluation in this population.

Binimetinib in combination with nivolumab or nivolumab and ipilimumab in patients with previously treated microsatellite-stable metastatic colorectal cancer with RAS mutations in an open-label phase 1b/2 study

BACKGROUND

In patients with previously treated RAS-mutated microsatellite-stable (MSS) metastatic colorectal cancer (mCRC), a multicenter open-label phase 1b/2 trial was conducted to define the safety and efficacy of the MEK1/MEK2 inhibitor binimetinib in combination with the immune checkpoint inhibitor (ICI) nivolumab (anti-PD-1) or nivolumab and another ICI, ipilimumab (anti-CTLA4).

METHODS

In phase 1b, participants were randomly assigned to Arm 1A (binimetinib 45 mg twice daily [BID] plus nivolumab 480 mg once every 4 weeks [Q4W]) or Arm 1B (binimetinib 45 mg BID plus nivolumab 480 mg Q4W and ipilimumab 1 mg/kg once every 8 weeks [Q8W]) to determine the maximum tolerable dose (MTD) and recommended phase 2 dose (RP2D) of binimetinib. The MTD/RP2D was defined as the highest dosage combination that did not cause medically unacceptable dose-limiting toxicities in more than 35% of treated participants in Cycle 1. During phase 2, participants were randomly assigned to Arm 2A (binimetinib MTD/RP2D plus nivolumab) or Arm 2B (binimetinib MTD/RP2D plus nivolumab and ipilimumab) to assess the safety and clinical activity of these combinations.

RESULTS

In phase 1b, 21 participants were randomized to Arm 1A or Arm 1B; during phase 2, 54 participants were randomized to Arm 2A or Arm 2B. The binimetinib MTD/RP2D was determined to be 45 mg BID. In phase 2, no participants receiving binimetinib plus nivolumab achieved a response. Of the 27 participants receiving binimetinib, nivolumab, and ipilimumab, the overall response rate was 7.4% (90% CI: 1.3, 21.5). Out of 75 participants overall, 74 (98.7%) reported treatment-related adverse events (AEs), of whom 17 (22.7%) reported treatment-related serious AEs.

CONCLUSIONS

The RP2D binimetinib regimen had a safety profile similar to previous binimetinib studies or nivolumab and ipilimumab combination studies. There was a lack of clinical benefit with either drug combination. Therefore, these data do not support further development of binimetinib in combination with nivolumab or nivolumab and ipilimumab in RAS-mutated MSS mCRC.

TRIAL REGISTRATION

NCT03271047 (09/01/2017).

Phase Ib/II Study of the Efficacy and Safety of Binimetinib (MEK162) Plus Panitumumab for Mutant or Wild-Type RAS Metastatic Colorectal Cancer

INTRODUCTION

Activating RAS gene mutations occur in approximately 55% of patients with metastatic colorectal cancer (mCRC) and are associated with poorer clinical outcomes due to epidermal growth factor receptor (EGFR) blockade resistance. Combined EGFR and mitogen-activated protein kinase (MEK) inhibition may extend response to EGFR inhibition and overcome acquired resistance. This phase Ib/II dose escalation trial evaluated the safety and activity of dual inhibition with binimetinib (MEK1/2 inhibitor) and panitumumab (EGFR inhibitor [EGFRi]) in patients with RAS mutant or BRAF wild type (WT)/RAS WT mCRC.

METHODS

Phase Ib dose escalation started with binimetinib 45 mg twice daily plus panitumumab 6 mg/kg administered every 2 weeks. In the phase II study, patients with measurable mCRC were enrolled into 4 groups based on previous anti-EGFR monoclonal antibody therapy and RAS mutational status.

RESULTS

No patients in the phase Ib portion (n = 10) had a response; 70% of patients had stable disease. In the phase II portion (n = 43), overall response rate (ORR, confirmed) was 2.3% with one partial response in the RAS WT group, DCR was 30.2%, and median progression-free survival was 1.8 months (95%CI, 1.6-3.3). All patients experienced ≥1 adverse event, with the most common being diarrhea (71.7%), vomiting (52.8%), nausea (50.9%), fatigue (49.1%), dermatitis acneiform (43.4%), and rash (41.5%). Most patients required treatment interruption or dose reduction due to difficulties tolerating treatment.

CONCLUSIONS

The combination of binimetinib and panitumumab had substantial toxicity and limited clinical activity for patients with mutant or WT RAS mCRC, independent of EGFRi treatment history (Trial registration: NCT01927341).

A phase I/IB trial of binimetinib in combination with erlotinib in NSCLC harboring activating KRAS or EGFR mutations

BACKGROUND

Activating mutations in EGFR or KRAS are highly prevalent in NSCLC, share activation of the MAPK pathway and may be amenable to combination therapy to prevent negative feedback activation.

METHODS

In this phase 1/1B trial, we tested the combination of binimetinib and erlotinib in patients with advanced NSCLC with at least 1 prior line of treatment (unless with activating EGFR mutation which could be treatment-naïve). A subsequent phase 1B expansion accrued patients with either EGFR- or KRAS-mutation using the recommended phase 2 dose (RP2D) from Phase 1. The primary objective was to evaluate the safety of binimetinib plus erlotinib and establish the RP2D.

RESULTS

43 patients enrolled (dose-escalation = 23; expansion = 20). 17 harbored EGFR mutation and 22 had KRAS mutation. The RP2D was erlotinib 100 mg daily and binimetinib 15 mg BID × 5 days/week. Common AEs across all doses included diarrhea (69.8%), rash (44.2%), fatigue (32.6%), and nausea (32.6%), and were primarily grade 1/2. Among KRAS mutant patients, 1 (5%) had confirmed partial response and 8 (36%) achieved stable disease as best overall response. Among EGFR mutant patients, 9 were TKI-naïve with 8 (89%) having partial response, and 8 were TKI-pretreated with no partial responses and 1 (13%) stable disease as best overall response.

CONCLUSIONS

Binimetinib plus erlotinib demonstrated a manageable safety profile and modest efficacy including one confirmed objective response in a KRAS mutant patient. While clinical utility of this specific combination was limited, these results support development of combinations using novel small molecule inhibitors of RAS, selective EGFR- and other MAPK pathway inhibitors, many of which have improved therapeutic indices.

CLINICAL TRIAL REGISTRATION

NCT01859026.

Chemistry and Pharmacology of Fluorinated Drugs Approved by the FDA (2016-2022)

Fluorine is characterized by high electronegativity and small atomic size, which provide this molecule with the unique property of augmenting the potency, selectivity, metabolic stability, and pharmacokinetics of drugs. Fluorine (F) substitution has been extensively explored in drug research as a means of improving biological activity and enhancing chemical or metabolic stability. Selective F substitution onto a therapeutic or diagnostic drug candidate can enhance several pharmacokinetic and physicochemical properties such as metabolic stability and membrane permeation. The increased binding ability of fluorinated drug target proteins has also been reported in some cases. An emerging line of research on F substitution has been addressed by using 18F as a radiolabel tracer atom in the extremely sensitive methodology of positron emission tomography (PET) imaging. This review aims to report on the fluorinated drugs approved by the US Food and Drug Administration (FDA) from 2016 to 2022. It cites selected examples from a variety of therapeutic and diagnostic drugs. FDA-approved drugs in this period have a variety of heterocyclic cores, including pyrrole, pyrazole, imidazole, triazole, pyridine, pyridone, pyridazine, pyrazine, pyrimidine, triazine, purine, indole, benzimidazole, isoquinoline, and quinoline appended with either F-18 or F-19. Some fluorinated oligonucleotides were also authorized by the FDA between 2019 and 2022.

Avelumab or talazoparib in combination with binimetinib in metastatic pancreatic ductal adenocarcinoma: dose-finding results from phase Ib of the JAVELIN PARP MEKi trial

BACKGROUND

Combinations of avelumab [anti-programmed death-ligand 1 (anti-PD-L1)] or talazoparib [poly(adenosine diphosphate ribose) polymerase (PARP) inhibitor] with binimetinib (MEK inhibitor) were expected to result in additive or synergistic antitumor activity relative to each drug administered alone. Here, we report phase Ib results from JAVELIN PARP MEKi, which investigated avelumab or talazoparib combined with binimetinib in metastatic pancreatic ductal adenocarcinoma (mPDAC).

PATIENTS AND METHODS

Patients with mPDAC that had progressed with prior treatment received avelumab 800 mg every 2 weeks plus binimetinib 45 mg or 30 mg two times daily (continuous), or talazoparib 0.75 mg daily plus binimetinib 45 mg or 30 mg two times daily (7 days on/7 days off). The primary endpoint was dose-limiting toxicity (DLT).

RESULTS

A total of 22 patients received avelumab plus binimetinib 45 mg (n = 12) or 30 mg (n = 10). Among DLT-evaluable patients, DLT occurred in five of 11 patients (45.5%) at the 45-mg dose, necessitating de-escalation to 30 mg; DLT occurred in three of 10 patients (30.0%) at the 30-mg dose. Among patients treated at the 45-mg dose, one (8.3%) had a best overall response of partial response. Thirteen patients received talazoparib plus binimetinib 45 mg (n = 6) or 30 mg (n = 7). Among DLT-evaluable patients, DLT occurred in two of five patients (40.0%) at the 45-mg dose, necessitating de-escalation to 30 mg; DLT occurred in two of six patients (33.3%) at the 30-mg dose. No objective responses were observed.

CONCLUSIONS

Combinations of avelumab or talazoparib plus binimetinib resulted in higher-than-expected DLT rates. However, most DLTs were single occurrences, and the overall safety profiles were generally consistent with those reported for the single agents.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.govNCT03637491; https://clinicaltrials.gov/ct2/show/NCT03637491.

A phase Ib trial of combined PKC and MEK inhibition with sotrastaurin and binimetinib in patients with metastatic uveal melanoma

Background

Uveal melanoma is a disease characterized by constitutive activation of the G alpha pathway and downstream signaling of protein kinase C (PKC) and the mitogen-activated protein kinase (MAPK) pathway. While limited clinical activity has been observed in patients with metastatic disease with inhibition of PKC or MEK alone, preclinical data has demonstrated synergistic antitumor effects with concurrent inhibition of PKC and MEK.

Method

We conducted a phase Ib study of the PKC inhibitor sotrastaurin in combination with the MEK inhibitor binimetinib in patients with metastatic uveal melanoma using a Bayesian logistic regression model guided by the escalation with overdose control principle (NCT01801358). Serial blood samples and paired tumor samples were collected for pharmacokinetic (PK) and pharmacodynamic analysis.

Results

Thirty-eight patients were treated across six dose levels. Eleven patients experienced DLTs across the five highest dose levels tested, most commonly including vomiting (n=3), diarrhea (n=3), nausea (n=2), fatigue (n=2) and rash (n=2). Common treatment related adverse events included diarrhea (94.7%), nausea (78.9%), vomiting (71.1%), fatigue (52.6%), rash (39.5%), and elevated blood creating phosphokinase (36.8%). Two dose combinations satisfying criteria for the maximum tolerated dose (MTD) were identified: (1) sotrastaurin 300 mg and binimetinib 30 mg; and, (2) sotrastaurin 200 mg and binimetinib 45 mg. Exposure to both drugs in combination was consistent with single-agent data for either drug, indicating no PK interaction between sotrastaurin and binimetinib. Stable disease was observed in 60.5% of patients treated. No patient achieved a radiographic response per RECIST v1.1.

Conclusions

Concurrent administration of sotrastaurin and binimetinib is feasible but associated with substantial gastrointestinal toxicity. Given the limited clinical activity achieved with this regimen, accrual to the phase II portion of the trial was not initiated.

Combination Therapies for Advanced Biliary Tract Cancer

Biliary tract cancers (BTCs) are a group of malignant neoplasms that have recently increased in incidence and have a poor prognosis. Surgery is the only curative therapy. However, most patients are only indicated for palliative therapy because of advanced-stage disease at diagnosis and rapid progression. The current first-line treatment for advanced BTC is gemcitabine and cisplatin chemotherapy. Nonetheless, many patients develop resistance to this regimen. Over the years, few chemotherapy regimens have managed to improve the overall survival of patients. Accordingly, novel therapies such as targeted therapy have been introduced to treat this patient population. Extensive research on tumorigenesis and the genetic profiling of BTC have revealed the heterogenicity and potential target pathways, such as EGFR, VEGF, MEK/ERK, PI3K and mTOR. Moreover, mutational analysis has documented the presence of IDH1, FGFR2, HER2, PRKACA, PRKACB, BRAF, and KRAS gene aberrations. The emergence of immunotherapy in recent years has expanded the treatment landscape for this group of malignancies. Cancer vaccines, adoptive cell transfer, and immune checkpoint inhibitors have been extensively investigated in trials of BTC. Therefore, patient stratification and a combination of various therapies have become a reasonable and important clinical strategy to improve patient outcomes. This review elaborates the literature on combined treatment strategies for advanced BTC from the past few years and ongoing clinical trials to provide new inspiration for the treatment of advanced BTC.

Structures of human TR4LBD-JAZF1 and TR4DBD-DNA complexes reveal the molecular basis of transcriptional regulation

Testicular nuclear receptor 4 (TR4) modulates the transcriptional activation of genes and plays important roles in many diseases. The regulation of TR4 on target genes involves direct interactions with DNA molecules via the DNA-binding domain (DBD) and recruitment of coregulators by the ligand-binding domain (LBD). However, their regulatory mechanisms are unclear. Here, we report high-resolution crystal structures of TR4DBD, TR4DBD-DNA complexes and the TR4LBD-JAZF1 complex. For DNA recognition, multiple factors come into play, and a specific mutual selectivity between TR4 and target genes is found. The coactivators SRC-1 and CREBBP can bind at the interface of TR4 originally occupied by the TR4 activation function region 2 (AF-2); however, JAZF1 suppresses the binding through a novel mechanism. JAZF1 binds to an unidentified surface of TR4 and stabilizes an α13 helix never reported in the nuclear receptor family. Moreover, the cancer-associated mutations affect the interactions and the transcriptional activation of TR4 in vitro and in vivo, respectively. Overall, our results highlight the crucial role of DNA recognition and a novel mechanism of how JAZF1 reinforces the autorepressed conformation and influences the transcriptional activation of TR4, laying out important structural bases for drug design for a variety of diseases, including diabetes and cancers.

First-in-human phase I dose-escalation and dose-expansion trial of the selective MEK inhibitor HL-085 in patients with advanced melanoma harboring NRAS mutations

BACKGROUND

HL-085 is a selective, orally administered MEK1/2 inhibitor. We aimed to evaluate the safety and efficacy of HL-085 in patients with advanced melanoma harboring NRAS mutations.

METHODS

This was a multicenter phase 1 study. HL-085 was administered twice daily in a standard 3 + 3 dose-escalation design (10 dose cohorts; 0.5-18 mg twice daily), followed by dose expansion at the recommended phase II dose (RP2D). The primary endpoints included tolerability, dose-limiting toxicity (DLT), maximum tolerated dose (MTD) and RP2D.

RESULTS

Between September 13, 2017, and January 18, 2021, 42 patients were enrolled (dose escalation phase: n = 30; dose expansion phase: n = 12). No DLT was reported during dose escalation and MTD was not reached with HL-085 doses up to 18 mg twice daily. The RP2D was 12 mg twice daily. The most common all-grade drug-related adverse events (AEs) across all dose levels were rash (61.9%), increased creatine phosphokinase (CK, 59.5%), face edema (50.0%), increased aspartate aminotransferase (47.6%), peripheral edema (40.5%), diarrhea (33.3%), alanine aminotransferase (33.3%), and paronychia (19.0%), most of which were grade 1 and 2. Most frequency of grade ≥ 3 AEs were CK (14.2%), asthenia (7.1%), peripheral edema (4.8%), and acneiform dermatitis (4.8%). In the cohort of 12 mg twice daily dose (15 patients), confirmed objective response rate was 26.7%; disease control rate was 86.7%; median duration of response was 2.9 months; median progression-free survival was 3.6 months.

CONCLUSIONS

The HL-085 showed acceptable tolerability and substantial clinical activity in patients with advanced melanoma harboring NRAS mutations.

TRIAL REGISTRATION

Trial registration ClinicalTrials.gov number: NCT03973151.

BRAF and MEK Inhibitors and Their Toxicities: A Meta-Analysis

PURPOSE

This meta-analysis summarizes the incidence of treatment-related adverse events (AE) of BRAFi and MEKi.

METHODS

A systematic search of Medline/PubMed was conducted to identify suitable articles published in English up to 31 December 2021. The primary outcomes were profiles for all-grade and grade 3 or higher treatment-related AEs, and the analysis of single side effects belonging to both categories.

RESULTS

The overall incidence of treatment-related all-grade Aes was 99% for Encorafenib (95% CI: 0.97-1.00) and 97% for Trametinib (95% CI: 0.92-0.99; I² = 66%) and Binimetinib (95% CI: 0.94-0.99; I² = 0%). In combined therapies, the rate was 98% for both Vemurafenib + Cobimetinib (95% CI: 0.96-0.99; I² = 77%) and Encorafenib + Binimetinib (95% CI: 0.96-1.00). Grade 3 or higher adverse events were reported in 69% of cases for Binimetinib (95% CI: 0.50-0.84; I² = 71%), 68% for Encorafenib (95% CI: 0.61-0.74), and 72% for Vemurafenib + Cobimetinib (95% CI: 0.65-0.79; I² = 84%). The most common grade 1-2 AEs were pyrexia (43%) and fatigue (28%) for Dabrafenib + Trametinib and diarrhea for both Vemurafenib + Cobimetinib (52%) and Encorafenib + Binimetinib (34%). The most common AEs of grade 3 or higher were pyrexia, rash, and hypertension for Dabrafenib + Trametinib (6%), rash and hypertension for Encorafenib + Binimetinib (6%), and increased AST and ALT for Vemurafenib + Cobimetinib (10%).

CONCLUSIONS

Our study provides comprehensive data on treatment-related adverse events of BRAFi and MEKi combination therapies, showing related toxicity profiles to offer a helpful tool for clinicians in the choice of therapy.

Safety and Clinical Activity of SHR7390 Monotherapy or Combined With Camrelizumab for Advanced Solid Tumor: Results From Two Phase I Trials

BACKGROUND

SHR7390 is a novel, selective MEK1/2 inhibitor. Here, we report results from two phase I trials conducted to evaluate the tolerability, safety and antitumor activity of SHR7390 monotherapy for advanced solid tumors and SHR7390 plus camrelizumab for treatment-refractory advanced or metastatic colorectal cancer (CRC).

PATIENTS AND METHODS

Patients received SHR7390 alone or combined with fixed-dose camrelizumab (200 mg every 2 weeks) in an accelerated titration scheme to determine the maximum tolerated dose (MTD). A recommended dose for expansion was determined based on the safety and tolerability of the dose-escalation stage. The primary endpoints were dose limiting toxicity (DLT) and MTD.

RESULTS

In the SHR7390 monotherapy trial, 16 patients were enrolled. DLTs were reported in the 1.0 mg cohort, and the MTD was 0.75 mg. Grade ≥3 treatment-related adverse events (TRAEs) were recorded in 4 patients (25.0%). No patients achieved objective response. In the SHR7390 combination trial, 22 patients with CRC were enrolled. One DLT was reported in the 0.5 mg cohort and the MTD was not reached. Grade ≥3 TRAEs were observed in 8 patients (36.4%), with the most common being rash (n=4). One grade 5 TRAE (increased intracranial pressure) occurred. Five patients (22.7%) achieved partial response, including one of 3 patients with MSS/MSI-L and BRAF mutant tumors, one of 15 patients with MSS/MSI-L and BRAF wild type tumors, and all 3 patients with MSI-H tumors.

CONCLUSIONS

SHR7390 0.5 mg plus camrelizumab showed a manageable safety profile. Preliminary clinical activity was reported regardless of MSI and BRAF status.

MEK inhibitors for neurofibromatosis type 1 manifestations: Clinical evidence and consensus

The wide variety of clinical manifestations of the genetic syndrome neurofibromatosis type 1 (NF1) are driven by overactivation of the RAS pathway. Mitogen-activated protein kinase kinase inhibitors (MEKi) block downstream targets of RAS. The recent regulatory approvals of the MEKi selumetinib for inoperable symptomatic plexiform neurofibromas in children with NF1 have made it the first medical therapy approved for this indication in the United States, the European Union, and elsewhere. Several recently published and ongoing clinical trials have demonstrated that MEKi may have potential benefits for a variety of other NF1 manifestations, and there is broad interest in the field regarding the appropriate clinical use of these agents. In this review, we present the current evidence regarding the use of existing MEKi for a variety of NF1-related manifestations, including tumor (neurofibromas, malignant peripheral nerve sheath tumors, low-grade glioma, and juvenile myelomonocytic leukemia) and non-tumor (bone, pain, and neurocognitive) manifestations. We discuss the potential utility of MEKi in related genetic conditions characterized by overactivation of the RAS pathway (RASopathies). In addition, we review practical treatment considerations for the use of MEKi as well as provide consensus recommendations regarding their clinical use from a panel of experts.

Phase I pharmacokinetic study of an oral, small-molecule MEK inhibitor tunlametinib in patients with advanced NRAS mutant melanoma

Background: Malignant melanoma is an aggressive disease. Tunlametinib (HL-085) is a potent, selective, and orally bioavailable MEK1/2 inhibitor. The objective of this study was to determine the pharmacokinetics (PK) of tunlametinib and its main metabolite M8 in patients with NRAS-mutant melanoma following a single dose and multiple doses in a phase I safety and PK study.

Methods: A multiple-center phase I study was performed in patients with melanoma including dose-escalation phase and dose-expansion phase. PK following a single oral dose and multiple doses of 0.5–18 mg twice daily was assessed.

Results: A total of 30 participants were included in the dose escalation phase and then 11 patients were included in the dose-expansion phase (12 mg twice daily). Tunlametinib plasma concentration rapidly increased after dosing, with a T_max of 0.5–1 h. Mean elimination half-life (t_1/2) was dose-independent and had a range from 21.84 to 34.41 h. Mean apparent clearance (CL/F) and distribution volume (V/F) were 28.44–51.93 L/h and 1199.36–2009.26 L, respectively. The average accumulation ratios of AUC and C_max after the multiple administration of tunlametinib were 1.64–2.73 and 0.82–2.49, respectively. Tunlametinib was rapidly transformed into the main metabolite M8 and M8 reached the peak concentration about 1 h after administration. Mean t_1/2 of M8 was 6.1–33.54 h. The body exposure of M8 in plasma was 36%–67% of that of tunlametinib. There were general dose-proportional increases in maximum concentration (C_max) and area under the curve (AUC) of tunlametinib and M8 both in the single dose phase and in the multiple doses phase.

Conclusion: Tunlametinib was absorbed rapidly and eliminated at a medium speed after drug withdrawal. Pharmacokinetic body exposure increased in general dose-proportional manner from 0.5 mg up to 18 mg. Slight accumulation was found after multiple oral doses. The pharmacokinetics of tunlametinib and its metabolite suggest that twice daily dosing is appropriate for tunlametinib.

Phase Ib/II Trial of Ribociclib in Combination with Binimetinib in Patients with NRAS-mutant Melanoma

PURPOSE

Enhanced MAPK pathway signaling and cell-cycle checkpoint dysregulation are frequent in NRAS-mutant melanoma and, as such, the regimen of the MEK inhibitor binimetinib and the selective CDK4/6 inhibitor ribociclib is a rational combination.

PATIENTS AND METHODS

This is a phase Ib/II, open-label study of ribociclib + binimetinib in patients with NRAS-mutant melanoma (NCT01781572). Primary objectives were to estimate the MTD/recommended phase II dose (RP2D) of the combination (phase Ib) and to characterize combination antitumor activity at the RP2D (phase II). Tumor genomic characterization and pharmacokinetics/pharmacodynamics were also evaluated.

RESULTS

Ten patients (16.4%) experienced dose-limiting toxicities in cycle 1 of phase Ib. Overall response rate in the phase II cohort (n = 41) for the selected RP2D (binimetinib 45 mg twice daily + ribociclib 200 mg once daily, 21 days on/7 days off) was 19.5% [8/41; 95% confidence interval (CI), 8.8-34.9]. The response rate was 32.5% (13/40; 95% CI, 20.1-48.0) in patients with NRAS mutation with concurrent alterations of CDKN2A, CDK4, or CCND1. Median progression-free survival was 3.7 months (95% CI, 3.5-5.6) and median overall survival was 11.3 months (95% CI, 9.3-14.2) for all patients. Common treatment-related toxicities included creatine phosphokinase elevation, rash, edema, anemia, nausea, diarrhea, and fatigue. Pharmacokinetics and safety were consistent with single-agent data, supporting a lack of drug-drug interaction.

CONCLUSIONS

Ribociclib + binimetinib can be safely administered and is clinically active in patients with NRAS-mutant melanoma. Co-mutations of cell-cycle genes may define a population with greater likelihood of treatment benefit. See related commentary by Moschos, p. 2977.

Melanomas with concurrent BRAF non-p.V600 and NF1 loss-of-function mutations are targetable by BRAF/MEK inhibitor combination therapy

Although combination BRAF/MEK inhibition has produced significant survival benefits for BRAF p.V600 mutant melanomas, targeted therapies approved for BRAF non-p.V600 mutant melanomas remain limited. Through the analysis of 772 cutaneous melanoma exomes, we reveal that BRAF non-p.V600 mutations co-occurs more frequently with NF1 loss, but not with oncogenic NRAS mutations, than expected by chance. We present cell signaling data, which demonstrate that BRAF non-p.V600 mutants can signal as monomers and dimers within an NF1 loss context. Concordantly, BRAF inhibitors that inhibit both monomeric and dimeric BRAF synergize with MEK inhibition to significantly reduce cell viability in vitro and tumor growth in vivo in BRAF non-p.V600 mutant melanomas with co-occurring NF1 loss-of-function mutations. Our data suggest that patients harboring BRAF non-p.V600 mutant melanomas may benefit from current FDA-approved BRAF/MEK inhibitor combination therapy currently reserved for BRAF p.V600 mutant patients.

MEK inhibitors for pre-treated, NRAS-mutated metastatic melanoma: A multi-centre, retrospective study

BACKGROUND

MEK inhibitors (MEKi) have shown clinical efficacy for NRAS-mutated, metastasized melanoma in randomised controlled trials, yet their clinical use is currently restricted to advanced, pre-treated patients, which is a different situation compared to previous trials. Data on their efficacy in the current real-world use are scarce.

METHODS

In this retrospective, multi-centre study, we evaluated the clinical course of disease of patients treated with MEKi with at least one previous treatment line in five German cancer centres.

RESULTS

Thirty-three patients were included, 19 males (58%) and 14 females (42%), with a median age of 64 years. Ninety-one percent of patients were pre-treated with immune checkpoint inhibitors, 90% of patients had elevated serum lactate dehydrogenase (LDH) levels at treatment initiation, 33% suffered from cerebral metastases and 30% had an Eastern Cooperative Oncology Group performance status of 2 or higher. The response rate was 18.2%; the disease control rate was 48.5%. Median progression-free survival was 2.8 months (95% confidence interval (CI): 1.6-3.9 months), and median overall survival was 7.1 months (95% CI: 5.8-8.3 months). In subgroup analysis, clinical efficacy was similar also in patients with high LDH levels and cerebral metastases, and there was a better outcome in males and in patients treated with trametinib vs. other MEKi, which may be based on selection bias. Overall, the clinical efficacy was similar compared to previous clinical trials in earlier treatment lines.

CONCLUSIONS

MEKi fulfil the need for an in-between treatment to stabilise the course of disease in advanced NRAS-mutated melanoma, but expectations regarding ongoing tumour response should be tempered.

Encorafenib, binimetinib plus pembrolizumab triplet therapy in patients with advanced BRAFV600 mutant melanoma: safety and tolerability results from the phase I IMMU-TARGET trial

BACKGROUND

Combination of immune checkpoint inhibitors and mitogen-activated protein kinase (MAPK) pathway inhibitors (MAPKi) has been proposed to enhance the durability of anti-tumour responses induced by MAPKi. Here, we present phase I safety results from an open-label, phase I/II study of pembrolizumab (PEM), encorafenib (ENC) and binimetinib (BIN) triplet therapy in advanced, B-Raf proto-oncogene serine/threonine kinase (BRAF)V600-mutated melanoma (IMMU-TARGET, NCT02902042).

METHODS

The dose finding phase I part used a 3 + 3 design, starting with the approved doses of PEM (200 mg every three weeks), ENC (450 mg once daily [QD]) and BIN (45 mg twice daily [BID]) as dose level (DL) 0. Reduction of the ENC and BIN doses (300 mg QD and 30 mg BID at DL-1 and 200 mg QD and 30 mg BID at DL-2) was preplanned in case of ≥2 dose-limiting toxicities (DLTs). Primary objectives were to estimate the recommended phase II dose of the triplet combination, DLT and safety. As per the sponsor's decision, the study was terminated after the phase I part, as the clinical efficacy of the combination is currently being investigated in a pivotal, placebo-controlled (PEM mono), double-blinded phase III trial (STARBOARD,NCT04657991).

RESULTS

Fifteen patients were enrolled. DLTs of DL0 were creatine phosphokinase (CPK) elevation plus cytokine release syndrome (n = 1) and gamma glutamyl transferase (GGT) increase (n = 1). No DLT was observed in further 3 + 3 patients at DL-1. One (isolated GGT elevations) DLT of DL0 was questionable, as the patient had further episodes of isolated GGT elevations after treatment discontinuation. Hence, further 6 patients were enrolled at DL0: here, no DLT occurred. In total, 13 of 15 patients (87%) experienced a treatment-related adverse event (TRAE) and 8 patients (53%), a grade ≥III TRAE; there were no TRAE-related deaths. Increases in aspartate aminotransferases, GGT (6/15 patients) and CPK elevations (4/15) were the most common grade III-IV TRAE. In median, patients received triplet therapy for 24 weeks (interquartile range [IQR], 12-45). Of the 14 patients evaluable for efficacy, the overall response rate was 64% (95% confidence interval [CI], 35-87). At a median follow-up of 25 months (IQR, 9-28), progression-free survival at 12 months was 41% (95% CI, 13-68).

CONCLUSIONS

Triplet therapy with PEM, ENC and BIN as used in the study was feasible and safe and led to clinically meaningful disease control.

Diverse landscape of dermatologic toxicities from small-molecule inhibitor cancer therapy

BACKGROUND

Advances in molecular biology and genetics have contributed to breakthrough treatments directed at specific pathways associated with the development of cancer. Small-molecule inhibitors (Nibs) aimed at a variety of cellular pathways have been efficacious; however, they are associated with significant dermatologic toxicities.

METHODS

We conducted a comprehensive review of dermatologic toxicities associated with Nibs categorized into the following five groups: (a) mitogen-activated protein kinase; (b) growth factor/multi-tyrosine kinase; (c) cell division/DNA repair; (d) signaling associated with myeloproliferative neoplasms; and (e) other signaling pathways. Prospective phase I, II, or III clinical trials, retrospective literature reviews, systematic reviews/meta-analyses, and case reviews/reports were included for analysis.

RESULTS

Dermatologic toxicities reviewed were associated with every class of Nibs and ranged from mild to severe or life-threatening adverse skin reactions. Inflammatory reactions manifesting as maculopapular, papulopustular/acneiform, and eczematous lesions were frequent types of dermatologic toxicities seen with Nibs. Squamous cell carcinoma with keratoacanthoma-like features was associated with a subset of Nibs. Substantial overlap in dermatologic toxicities was found between Nibs.

CONCLUSIONS

Dermatologic toxicities from Nibs are diverse and may overlap between classes of Nibs. Recognition of the various types of toxicities from Nibs is critical for patient care in the era of "oncodermatology/dermatopathology."

Current Advances and Trends in KRAS Targeted Therapies for Colorectal Cancer

Kirsten Rat Sarcoma (KRAS) gene somatic point mutations is one of the most prominently mutated proto-oncogenes known to date, and accounts for approximately 60% of all colorectal cancer cases. One of the most exciting drug development areas against colorectal cancer is the targeting of undruggable kinases and kinase-substrate molecules, although whether and how they can be integrated with other therapies remains a question. Current clinical trial data have provided supporting evidence on the use of combination treatment involving MEK inhibitors and either one of the PI3K inhibitors for patients with metastatic colorectal cancer to avoid the development of resistance and provide effective therapeutic outcome rather than using a single agent alone. Many clinical trials are also ongoing to evaluate different combinations of these pathway inhibitors in combination with immunotherapy for patients with colorectal cancer whose current palliative treatment options are limited. Nevertheless, continued assessment of these targeted cancer therapies will eventually allow patients with colorectal cancer to be treated using a personalized medicine approach. In this review, the most recent scientific approaches and clinical trials targeting KRAS mutations directly or indirectly for the management of colorectal cancer are discussed.

Selection of Oral Therapeutics in China for the Treatment of Colorectal Cancer

OPINION STATEMENT

Intravenous administration of fluoropyrimidine-based chemotherapy has been the backbone of treatment in colorectal cancer (CRC) for decades. The availability of oral capecitabine has improved the tolerability and simplified combination schedules. In addition to capecitabine, several other oral drugs have proven efficacy, particularly in palliative treatment lines. Clinical guidelines describe several available third-line treatment options for metastatic CRC (mCRC), but few insights are provided to guide the selection and sequence. In this review, we describe the available evidence and most recent data concerning oral drugs with proven efficacy in CRC, including antiangiogenetic tyrosine kinase inhibitors (VEGFR TKIs), inhibitors blocking EGFR/Raf/MEK/ERK signaling pathway and modified fluoropyrimidine, and share recommendations and insights on selecting third-line oral therapies for mCRC in China. In general, third-line treatment options for mCRC are mainly regorafenib, fruquintinib, and chemo/targeted therapy reintroduction, while FTD/TPI was rarely used in China probably due to poor accessibility. Fruquintinib is preferred in patients with poor performance status (PS), elder age, and severe organ dysfunction, compared to regorafenib. New drugs of clinical trials were more recommended for the patients with BRAF mutant tumor, and those with good previous treatment efficacy tended to be recommended for chemo/targeted therapy reintroduction. The management of mCRC is evolving, and it must be emphasized that the consideration and recommendations presented here reflect current treatment practices in China and thus might change according to new clinical data as well as the availability of new oral drugs.

Differential Outcomes in Codon 12/13 and Codon 61 NRAS-Mutated Cancers in the Phase II NCI-MATCH Trial of Binimetinib in Patients with NRAS-Mutated Tumors

PURPOSE

Preclinical and clinical data suggest that downstream inhibition with an MEK inhibitor, such as binimetinib, might be efficacious for NRAS-mutated cancers.

PATIENTS AND METHODS

Patients enrolled in the NCI-MATCH trial master protocol underwent tumor biopsy and molecular profiling by targeted next-generation sequencing. Patients with NRAS-mutated tumors, except melanoma, were enrolled in subprotocol Z1A, a single-arm study evaluating binimetinib 45 mg twice daily. The primary endpoint was objective response rate (ORR). Secondary endpoints included progression-free survival (PFS) and overall survival (OS). A post hoc analysis examined the association of NRAS mutation type with outcome.

RESULTS

In total, 47 eligible patients with a refractory solid tumor harboring a codon 12, 13, or 61 NRAS mutation were treated. Observed toxicity was moderate, and 30% of patients discontinued treatment because of binimetinib-associated toxicity. The ORR was 2.1% (1/47 patients). A patient with malignant ameloblastoma harboring a codon 61 NRAS mutation achieved a durable partial response (PR). A patient with NRAS codon 61-mutated colorectal cancer had an unconfirmed PR, and two other patients with NRAS codon 61-mutated colorectal had stable disease for at least 12 months. In an exploratory analysis, patients with colorectal cancer bearing a NRAS codon 61 mutation (n = 8) had a significantly longer OS (P = 0.03) and PFS (P = 0.007) than those with codon 12 or 13 mutations (n = 16).

CONCLUSIONS

Single-agent binimetinib did not show promising efficacy in NRAS-mutated cancers. The observation of increased OS and PFS in patients with codon 61 NRAS-mutated colorectal cancer merits further investigation.

A phase I study of binimetinib (MEK 162), a MEK inhibitor, plus carboplatin and pemetrexed chemotherapy in non-squamous non-small cell lung cancer

INTRODUCTION

MEK inhibition is a potential therapeutic strategy in non-small cell lung cancer (NSCLC). This phase I study evaluates the MEK inhibitor binimetinib plus carboplatin and pemetrexed in stage IV non-squamous NSCLC patients (NCT02185690).

METHODS

A standard 3 + 3 dose-escalation design was used. Binimetinib 30 mg BID (dose level 1 [DL1]) or 45 mg BID (dose level 2 [DL2]) was given with standard doses of carboplatin and pemetrexed using an intermittent dosing schedule. The primary outcome was determination of the recommended phase II dose (RP2D) and safety of binimetinib. Secondary outcomes included efficacy, pharmacokinetics, and an exploratory analysis of response based on mutation subtype.

RESULTS

Thirteen patients (6 DL1, 7 DL2) were enrolled: 7 KRAS, 5 EGFR, and 1 NRAS mutation. The RP2D was binimetinib 30 mg BID. Eight patients (61.5%) had grade 3/4 adverse events, with dose limiting toxicities in 2 patients at DL2. Twelve patients were evaluated for response, with an investigator-assessed objective response rate (ORR) of 50% (95% CI 21.1%-78.9%; ORR 33.3% by independent-review, IR), and disease control rate 83.3% (95% CI 51.6%-97.9%). Median progression free survival (PFS) was 4.5 months (95% CI 2.6 months-NA), with a 6-month and 12-month PFS rate of 38.5% (95% CI 19.3%-76.5%) and 25.6% (95% CI 8.9%-73.6%), respectively. In an exploratory analysis, KRAS/NRAS-mutated patients had an ORR of 62.5% (ORR 37.5% by IR) vs. 25% in KRAS/NRAS wild-type patients. In MAP2K1-mutated patients, the ORR was 42.8%.

CONCLUSION

The addition of binimetinib to carboplatin and pemetrexed appears to have manageable toxicity with evidence of activity in advanced non-squamous NSCLC.

Trametinib-associated Hyponatremia in a Child With Low-grade Glioma is Not Seen Following Treatment With Alternative MEK Inhibitor

Molecularly targeted therapy with MEK inhibitors has been increasingly incorporated into the treatment of pediatric low-grade gliomas, but this promising therapy is associated with distinctive and specific toxicities. Understanding life-threatening MEK inhibitor toxicities and their management is critical to MEK inhibitor safety, especially among young children. This report describes severe hyponatremia associated with trametinib in an infant with progressive low-grade glioma without underlying endocrine dysfunction, which recurred despite significant dose reduction. Therapy with an alternative MEK inhibitor, binimetinib, provided excellent tumor response without hyponatremia, suggesting that some toxicities may be avoided by changing MEK inhibitor agents within the same class.

Identifying treatment options for BRAFV600 wild-type metastatic melanoma: A SU2C/MRA genomics-enabled clinical trial

Although combination BRAF and MEK inhibitors are highly effective for the 40-50% of cutaneous metastatic melanomas harboring BRAFV600 mutations, targeted agents have been ineffective for BRAFV600wild-type (wt) metastatic melanomas. The SU2C Genomics-Enabled Medicine for Melanoma Trial utilized a Simon two-stage optimal design to assess whether comprehensive genomic profiling improves selection of molecular-based therapies for BRAFV600wt metastatic melanoma patients who had progressed on standard-of-care therapy, which may include immunotherapy. Of the response-evaluable patients, binimetinib was selected for 20 patients randomized to the genomics-enabled arm, and nine were treated on the alternate treatment arm. Response rates for 27 patients treated with targeted recommendations included one (4%) partial response, 18 (67%) with stable disease, and eight (30%) with progressive disease. Post-trial genomic and protein pathway activation mapping identified additional drug classes that may be considered for future studies. Our results highlight the complexity and heterogeneity of metastatic melanomas, as well as how the lack of response in this trial may be associated with limitations including monotherapy drug selection and the dearth of available single and combination molecularly-driven therapies to treat BRAFV600wt metastatic melanomas.

MAPK blockade, toxicities, pathogenesis and management

PURPOSE OF REVIEW

BRAF/MEK inhibitor has changed the treatment landscape in patients with advanced and metastatic melanoma with prolonged overall survival and progression-free survival. Since three treatment combinations exist with similar efficacy therapy decisions are often made based on the side effect profile. Additionally, on-target side effects or class effects have to be properly managed to ensure treatment adherence.

RECENT FINDINGS

Sequential treatment with BRAF/MEK inhibition and immunotherapy might increase toxicity with a sepsis-like syndrome and triple therapy with concomitant BRAF/MEK inhibition and anti-PD1/PD-L1 antibody therapy induces severe side effects in the vast majority of patients.

SUMMARY

Toxicity of combination therapy with BRAF/MEK inhibitors is generally manageable, reversible and infrequently associated with treatment discontinuation. In case of persisting off-target effects the change to another combination therapy can resolve side effects.

Case Report: Combined CDK4/6 and MEK Inhibition in Refractory CDKN2A and NRAS Mutant Melanoma

There are only limited treatment options for metastatic NRAS mutant melanoma patients with resistance to immune checkpoint inhibitors. Besides activation of the mitogen-activated protein (MAP) kinase pathway, they often have additional disturbances in cell cycle regulation. However, unlike BRAF mutant melanoma, no targeted therapy has yet been approved for NRAS mutant melanoma so far. Here we present a NRAS mutant melanoma patient with response to combined binimetinib and ribociclib therapy following characterization of the molecular defects of the tumor by panel sequencing. Next generation sequencing (708 cancer genes) of a soft tissue metastasis revealed a homozygous deletion of CDKN2A in addition to the previously known NRAS mutation, as well as amplification of CCNE1 and CDK6. Immunohistochemical staining of the altered cell cycle genes confirmed loss of p16, reduced expression of p21 and high expression of CDK6 and cyclin D1. As the patient had been progressive on combined immunotherapy, targeted therapy with combined MEK and CDK4/6 inhibition was initiated as recommended by the molecular tumor board. Response to treatment was monitored with PET/CT and liquid biopsy, serum LDH, and S100. In addition, a patient-derived xenograft (PDX) was used to prove the efficacy of the two drugs in combination. Furthermore, senescence-associated beta-galactosidase staining showed that more cells were senescent under the combination treatment of binimetinib and ribociclib. Our case demonstrates how an individualized, molecular-based therapeutic approach could be found based on next-generation sequencing results. Furthermore our report highlights the fruitful and efficient collaboration of dermatooncologists, human geneticists, molecular pathologists, biochemists, radiologists, and nuclear physicians. Further studies are urgently needed to expand the very limited therapeutic landscape of NRAS mutated melanoma.

Defining and Targeting BRAF Mutations in Solid Tumors

OPINION STATEMENT

BRAF mutations are present in up to 8% of human cancers, and comprise a viable therapeutic target in many patients harboring these mutations. Specific BRAF-targeted therapies, such as vemurafenib, dabrafenib, and encorafenib, have transformed treatment of many BRAF-mutated cancers, producing meaningful clinical benefit with more tolerable safety profiles compared to prior standard-of-care treatments. BRAF inhibitors were first approved for use in metastatic melanoma, although resistance almost always limited their long-term effectiveness. Combination therapy with BRAF and MEK inhibitors has proven effective in delaying the onset of resistance, and produces additional clinical benefit across cancers. Although not promising initially in treatment of BRAF-mutated colorectal carcinoma, BRAF inhibitors in colorectal cancer were successfully combined with EGFR inhibitors, resulting in significant treatment response. Refining the use of BRAF and MEK inhibitors in less common tumor types (and for non-V600 mutations) and delaying the development of resistance remain pertinent future considerations in treating BRAF-mutated cancers. In this review, we will discuss the prevalence of BRAF mutations across human cancers and evidence on the efficacy and safety of current management strategies for various BRAF-mutant solid tumors.

Promising Molecular Targets for the Targeted Therapy of Biliary Tract Cancers: An Overview

Biliary tract cancer (BTC) is a leading cause of cancer-related death, due to the limited benefits of current systematic therapies and the heterogeneity of the tumor itself. High heterogeneity means that the clinical and molecular features vary between different subtypes of BTC, while the underlying molecular mechanisms remain unclear. Targeted therapy, where inhibitors are developed to selectively combine with targeted molecules in order to block abnormal signaling pathways in BTC, has shown promise as an emerging form of treatment for various types of cancer. In this article, a comprehensive review is conducted to examine potential molecular targets for BTC targeted therapy and their mechanisms. Furthermore, preliminary data published from clinical trials is utilized to analyze the main drugs used to combat BTC. The collective information presented in this article has provided useful insights into the current understanding of BTC.

New advances in the clinical management of RAS and BRAF mutant colorectal cancer patients

INTRODUCTION

In colorectal carcinogenesis, genetic alterations in RAS and BRAF oncogenes play an important role for cancer initiation and/or progression and represent a key focus in the search for targeted therapies. Despite many years of research and a great amount of studies, until very recently this pathway was considered extremely hard to downregulate to obtain a significant clinical impact in colorectal cancer patients. But better times are coming with the advent of new promising drugs and combinations strategies.

AREAS COVERED

In this review, we go over the biological characteristics of the MAPK pathway in colorectal tumors, while illustrating the clinical correlation of RAS and BRAF mutations, particularly its prognostic and predictive value. We also present newly data about recent improvements in the treatment strategy for patients harboring these types of tumors.

EXPERT COMMENTARY

With great advances in the knowledge of molecular basis of RAS and BRAF mutant colorectal cancer in conjunction with biotechnology development and the constant effort for improvement, in the near future many new therapeutic options would be available for the management of this group of patient with dismal prognosis.

Phase Ib Trial of the PI3K Inhibitor Copanlisib Combined with the Allosteric MEK Inhibitor Refametinib in Patients with Advanced Cancer

Background

Dual inhibition of PI3K and MAPK signaling is conceptually a promising anticancer therapy.

Objective

This phase 1b trial investigated the safety, maximum tolerated dose (MTD), recommended phase II dose, pharmacokinetics, tumor response, fluorodeoxyglucose positron emission tomography (FDG-PET) pharmacodynamics, and biomarker explorations for the combination of pan-PI3K inhibitor copanlisib and allosteric MEK inhibitor refametinib in patients with advanced solid tumors.

Patients and methods

This was an adaptive trial with eight dose cohorts combining dose escalation and varying schedules in repeated 28-day cycles. Patients received copanlisib (0.2–0.8 mg/kg intravenously) intermittently (days 1, 8, 15) or weekly (days 1, 8, 15, 22) each cycle, and refametinib (30–50 mg twice daily orally) continuously or 4 days on/3 days off. Patients with KRAS, NRAS, BRAF, or PI3KCA mutations were eligible for the expansion cohort.

Results

In the dose-escalation (n = 49) and expansion (n = 15) cohorts, the most common treatment-emergent adverse events included diarrhea (59.4%), nausea, acneiform rash, and fatigue (51.6% each). Dose-limiting toxicities included oral mucositis (n = 4), increased alanine aminotransferase/aspartate aminotransferase (n = 3), acneiform rash, hypertension (n = 2 each), and diarrhea (n = 1). MTD was copanlisib 0.4 mg/kg weekly and refametinib 30 mg twice daily. No pharmacokinetic interactions were identified. Decreased tumor FDG uptake and MEK-ERK signaling inhibition were demonstrated during treatment. Best response was stable disease (n = 21); median treatment duration was 6 weeks.

Conclusions

Despite sound rationale and demonstrable pharmacodynamic tumor activity in relevant tumor populations, a dose and schedule could not be identified for this drug combination that were both tolerable and offered clear efficacy in the population assessed.

Clinicaltrials.gov identifier

NCT01392521.

Electronic supplementary material

The online version of this article (10.1007/s11523-020-00714-0) contains supplementary material, which is available to authorized users.

Up-and-Coming Experimental Drug Options for Metastatic Colorectal Cancer

Colorectal cancer is one of the top causes of cancer and cancer-related deaths worldwide. The prognosis of metastatic colorectal cancer is poor and treatment options are limited. Many patients will run out of treatment options before they become medically unfit for therapy. As such, there is a need to expand upon the current understanding of disease biology as well as drug resistance mechanisms in order to create new approaches for therapy. In this review article, we will discuss the mechanistic rationale and clinical data for new drugs and therapeutic combinations under development for metastatic colorectal cancer.

Selective Oral MEK1/2 Inhibitor Pimasertib: A Phase I Trial in Patients with Advanced Solid Tumors

BACKGROUND

The Ras/Raf/mitogen-activated protein kinase kinase/extracellular signal-regulated kinase (Ras/Raf/MEK/ERK) signaling cascade is frequently constitutively activated in human cancers. Pimasertib is a selective and potent adenosine triphosphate non-competitive MEK1/2 inhibitor.

OBJECTIVE

Our objectives were to describe the results of a phase I, first-in-human, dose-escalation trial of pimasertib that investigated the maximum tolerated dose, recommended phase II dose, and safety, as well as other endpoints.

PATIENTS AND METHODS

Four dosing schedules of pimasertib (once daily [qd], 5 days on, 2 days off; qd, 15 days on, 6 days off; continuous qd; continuous twice daily [bid]) were evaluated in patients with advanced solid tumors. Each treatment cycle lasted 21 days. The primary objective was to determine the maximum tolerated dose based on dose-limiting toxicities (DLTs) evaluated during cycle 1, and the recommended phase II dose (RP2D). Secondary objectives included safety, pharmacokinetics, pharmacodynamics, and antitumor activity.

RESULTS

Overall, 180 patients received pimasertib (dose range 1-255 mg/day). DLTs were mainly observed at doses ≥ 120 mg/day and included skin rash/acneiform dermatitis and ocular events, such as serous retinal detachment. The most common drug-related adverse events were consistent with class effects, including diarrhea, skin disorders, ocular disorders, asthenia/fatigue, and peripheral edema. The median time to maximum pimasertib concentration was 1.5 h across dosing schedules, and the apparent terminal half-life was 5 h across qd dosing schedules. Pimasertib decreased ERK phosphorylation within 2 h of administration, which was maintained for up to 8 h at higher doses and prolonged with bid dosing.

CONCLUSIONS

Based on the safety profile and efficacy signals, a continuous bid regimen was the preferred dosing schedule and the RP2D was defined as 60 mg bid.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT00982865.

Evaluation of the RAS signaling network in response to MEK inhibition using organoids derived from a familial adenomatous polyposis patient

RAS signaling is a promising target for colorectal cancer (CRC) therapy, and a variety of selective inhibitors have been developed. However, their use has often failed to demonstrate a significant benefit in CRC patients. Here, we used patient-derived organoids (PDOs) derived from a familial adenomatous polyposis (FAP) patient to analyze the response to chemotherapeutic agents targeting EGFR, BRAF and MEK. We found that PDOs carrying KRAS mutations were resistant to MEK inhibition, while those harboring the BRAF class 3 mutation were hypersensitive. We used a systematic approach to examine the phosphorylation of RAS effectors using reverse-phase protein array (RPPA) and found increased phosphorylation of MEK induced by binimetinib. A high basal level of ERK phosphorylation and its rebound activation after MEK inhibition were detected in KRAS-mutant PDOs. Notably, the phosphorylation of EGFR and AKT was more closely correlated with that of MEK than that of ERK. Transcriptome analysis identified MYC-mediated transcription and IFN signaling as significantly correlated gene sets in MEK inhibition. Our experiments demonstrated that RPPA analysis of PDOs, in combination with the genome and transcriptome, is a useful preclinical research platform to understand RAS signaling and provides clues for the development of chemotherapeutic strategies.

OCULAR ADVERSE EVENTS ASSOCIATED WITH MEK INHIBITORS

PURPOSE

Mitogen-activates protein kinase (MAPK) inhibitors, particularly MEK inhibitors, have shifted the treatment paradigm for metastatic BRAF-mutant cutaneous melanoma; however, oncologists, ophthalmologists, and patients have noticed different toxicities of variable importance. This review aims to provide an update of the ocular adverse events (OAEs), especially retinal toxicity, associated with the use of MEK inhibitors.

METHODS

We conducted a scientific literature search using the PubMed database up to July 2018 with the terms "MEK inhibitors" with a "review" filter and "MEK inhibitors" with a "clinical trials" filter. Phase I-III experimental studies and reviews were selected. Current principles and techniques for diagnosing and managing MEK inhibitor retinopathy and other OAEs are discussed.

RESULTS

In patients treated with MEK inhibitors, including asymptomatic patients, OAEs occur with an incidence of up to 90%. Mild to severe ophthalmic toxicities are described, including visual disturbances, a 2-line decrease in Snellen visual acuity, dry eye symptoms, ocular adnexal abnormalities, visual field defects, panuveitis, and retinal toxicities, such as different degrees of MEK-associated retinopathy, vascular injury, and retinal vein occlusion.

CONCLUSION

MEK inhibitors can lead to different degrees of retinal, uveal, and adnexal OAE, causing visual disturbances or discomfort. One of the most relevant OAE of MEK therapy is MEK inhibitor-associated retinopathy (MEKAR), which is usually mild, self-limited, and may subside after continuous use of the drug for weeks or months, or discontinuation, thereby restoring the normal visual function of the retina, with some exceptions. Ocular adverse events are often associated with other systemic adverse effects that can modify the dosage of treatment, so the communication with the oncologist is fundamental.

Encorafenib, binimetinib and cetuximab combined therapy for patients with BRAFV600E mutant metastatic colorectal cancer

Approximately 10-15% of colorectal cancers (CRCs) harbor an activating BRAF mutation, leading to tumor growth promotion by activation of the mitogen-activated protein kinases pathway. BRAFV600E mutations are prognostic for treatment failure after first-line systemic therapy in the metastatic setting. In contrast to the efficacy of combined BRAF and MEK inhibition in melanoma, BRAFV600E mutant CRC is intrinsically unresponsive due to upregulation of HER/EGFR. However, combining the EGFR inhibitor cetuximab, the BRAF inhibitor encorafenib and the MEK inhibitor binimetinib improves overall survival. This review discusses the current treatment field for patients with BRAFV600E mutant metastatic CRC and summarizes the pharmacology, efficacy and safety of the novel doublet and triplet therapies consisting of encorafenib and cetuximab with or without binimetinib.

Systemic treatment options for advanced biliary tract carcinoma

Advanced biliary tract cancers (BTC) include a diverse collection of rare and heterogenous tumors with poor prognosis. The combination of gemcitabine and cisplatin is the established first-line therapy for advanced BTC. There are no accepted standard treatments in the second line setting, though there are several ongoing clinical trials that implement chemotherapy as a therapeutic strategy. The understanding of the molecular landscape of BTC has offered hope of targeted therapies to the identified actionable genomic aberrations, such as FGFR2 gene fusions, mutations of IDH1/2, HER2, BRAC1/2 and BRAF. Pembigatinib has become the first approved targeted therapy for BTC with FGFR2 fusion or other rearrangements. Recent immunotherapy has opened new therapy avenues in BTC with pembrolizumab approved for either microsatellite instability high (MSI-H) or DNA mismatch repair deficient (dMMR) advanced solid tumors, including BTC. The combination of immunotherapy with other modalities is currently being evaluated in different clinical trials, since single agent immunotherapy appears to provide modest benefits in advanced BTC. In this review, we summarize the current status of treatment options, including systemic chemotherapy, targeted therapy, immunotherapy, and various combinations in advanced BTC.

ERK phosphorylation as a marker of RAS activity and its prognostic value in non-small cell lung cancer

BACKGROUND

Deregulated signal transduction pathways play a key role in development, progression and therapeutic resistance of non-small cell lung cancers (NSCLC). The purpose of this study is to assess the downstream markers of two well-characterized pathways and to correlate them with clinical outcome.

DESIGN

670 patients with metastatic NSCLC were prospectively enrolled in a comprehensive biomarker profiling program at a single center from 2012 to 2016. Phosphorylation of extracellular signal-regulated kinase (p-ERK), and protein kinase B (p-AKT) was assessed by standardized immunohistochemistry. Product of scores for quantity and quality of staining were calculated (immunoreactive score, 0-9). Somatic mutations of Kirsten rat sarcoma viral oncogene homolog [KRAS], epithelial growth factor receptor [EGFR], v-Raf murine sarcoma viral oncogene homolog B [BRAF] and phosphatidylinositol 3-kinase [PIK3CA]) were detected by Sanger (2012-03/2015) and amplicon NGS (04/2015-02/2016). Patients enrolled during the first year (2012) were used as discovery cohort. Patients enrolled from 2013 to 02/2016 were used as validation cohort. Clinical data were retrieved from the electronic medical records and were analyzed retrospectively.

RESULTS

Using a discovery cohort, we identified an immunoreactive score of p-ERK ≥3 to be prognostically relevant. The validation cohort confirmed that higher levels of p-ERK correlated with worse overall survival (OS) and higher proportion of RAS mutations. Multivariate analysis including established risk factors such EGFR, ALK or ROS mutations and metastatic disease showed a trend of a detrimental effect of high p-ERK on OS (HR 1.23, CI 0.94-1.59, p = 0.131 for p-ERK immunoreactive score ≥3) and time to treatment failure after first-line therapy in the validation cohort. Phosphorylated AKT did not correlate with clinical outcome.

CONCLUSION

While serving as a prognosticator in univariate analysis, highly phosphorylated ERK does not convey a significant prognostic effect for OS in the presence of other prognostic factors. Phosphorylated ERK indicates a higher activity of RAS in advanced NSCLC.

A Phase Ib/II Study of the BRAF Inhibitor Encorafenib Plus the MEK Inhibitor Binimetinib in Patients with BRAFV600E/K -mutant Solid Tumors

PURPOSE

This open-label, dose-finding phase Ib/II study reports the safety and activity of the first combination use with BRAF inhibitor (BRAFi) encorafenib plus MEK inhibitor (MEKi) binimetinib in patients with BRAF V600E-mutant solid tumors.

PATIENTS AND METHODS

In phase I, the recommended phase 2 doses (RP2D) were established (primary objective). In phase II, the clinical activity of the combination at the RP2D was assessed (primary objective) in patients with BRAF-mutant metastatic colorectal cancer (mCRC), BRAFi-treated BRAF-mutant melanoma, and BRAFi-naïve BRAF-mutant melanoma.

RESULTS

A total of 126 patients with BRAF-mutant solid tumors were enrolled (phase I: 47 patients; phase II: 79 patients). The RP2D was encorafenib 450 mg once daily plus binimetinib 45 mg twice daily and pharmacokinetic data suggest that drug exposures of each agent were similar in combination compared with single-agent studies. In the phase II cohorts, confirmed responses were seen in two of 11 (18%) evaluable patients with mCRC, 11 of 26 (42%) evaluable patients with BRAFi-pretreated melanoma, and 28 of 42 (67%) BRAFi-naïve patients with melanoma. The most common grade 3/4 adverse event in phase II was increased alanine aminotransferase.

CONCLUSIONS

The combination of encorafenib (450 mg) plus binimetinib (45 mg) showed acceptable tolerability and encouraging activity in patients with BRAF V600-mutant tumors, which led to the dose selection for the melanoma COLUMBUS study. The safety profile of the combination was consistent with other approved BRAFi plus MEKi regimens, with several differences, including lower rates of dose-limiting pyrexia, arthralgia, and photosensitivity.

Randomised phase II trial (SWOG S1310) of single agent MEK inhibitor trametinib Versus 5-fluorouracil or capecitabine in refractory advanced biliary cancer

BACKGROUND

The rationale for the evaluation of trametinib in advanced biliary cancer (BC) is based on the presence of mitogen-activated protein kinase alterations and on earlier promising results with MEK inhibitors in BC.

METHODS

Patients with histologically proven BC who progressed on gemcitabine/platinum were randomised to trametinib daily (arm 1) versus fluoropyrimidine therapy (infusional 5-fluorouracil or oral capecitabine, arm 2). The primary end-point was overall survival (OS). Secondary end-points included progression free survival (PFS) and response rate. A planned interim futility analysis of objective response was performed on the first 14 patients registered to the trametinib arm.

RESULTS

The study was stopped early based on the lack of measurable response in the trametinib arm. A total of 44 eligible patients were randomised (24 patients in arm 1 and 20 patients in arm 2). Median age was 62 years and the primary sites of tumour were cholangiocarcinoma (68%) and gallbladder (32%). The overall response rate was 8% (95% CI 0%-19%) in arm 1 versus 10% (95% CI 0%-23%) in arm 2 (p > .99) Median OS was 4.3 months for arm 1 and 6.6 months for arm 2. The median PFS was 1.4 months for arm 1 and 3.3 months for arm 2.

CONCLUSIONS

This is the first prospective randomised study of a targeted agent versus chemotherapy for the second-line treatment of BC. In this unselected population, the interim analysis result of unlikely benefit with trametinib resulted in early closure.

Current Insights into Combination Therapies with MAPK Inhibitors and Immune Checkpoint Blockade

The recent development of high-throughput genomics has revolutionized personalized medicine by identifying key pathways and molecular targets controlling tumor progression and survival. Mitogen-activated protein kinase (MAPK) pathways are examples of such targets, and inhibitors against these pathways have shown promising clinical responses in patients with melanoma, non-small-cell lung cancer, colorectal cancer, pancreatic cancer, and thyroid cancer. Although MAPK pathway-targeted therapies have resulted in significant clinical responses in a large proportion of cancer patients, the rate of tumor recurrence is high due to the development of resistance. Conversely, immunotherapies have shown limited clinical responses, but have led to durable tumor regression in patients, and complete responses. Recent evidence indicates that MAPK-targeted therapies may synergize with immune cells, thus providing rationale for the development of combination therapies. Here, we review the current status of ongoing clinical trials investigating MAPK pathway inhibitors, such as BRAF and MAPK/ERK kinase (MEK) inhibitors, in combination with checkpoint inhibitors targeting programmed death protein 1 (PD-1), programmed death-ligand 1 (PD-L1), and cytotoxic T cell associated antigen-4 (CTLA-4). A better understanding of an individual drug's mechanism of action, patterns of acquired resistance, and the influence on immune cells will be critical for the development of novel combination therapies.

The discovery and development of binimetinib for the treatment of melanoma

INTRODUCTION

Binimetinib is an uncompetitive, small-molecule inhibitor of selective mitogen-activated protein kinase (MEK1/2) and was recently approved in 2018 in combination with encorafenib for the treatment of metastatic melanomas. Preclinical and clinical trial data on the drug demonstrate its potent efficacy in cancers, especially melanomas with BRAF and NRAS mutations.

AREAS COVERED

The authors review the preclinical as well as clinical Phase 1, 2 and 3 trial data leading to its FDA approval in 2018 for metastatic melanoma. Phase 3 data in combination with encorafenib demonstrated double the PFS (14.9 months) compared to vemurafenib alone (7.3 months) in patients with BRAF-mutated metastatic melanoma.

EXPERT OPINION

No longer-term data is available yet to demonstrate any durable complete responses to therapy with binimetinib or improvements in overall survival compared to other FDA-approved therapies including immunotherapy or vemurafenib. Treatment approaches to patients with BRAF-mutated metastatic melanoma should be individualized and binimetinib in combination with encorafenib is a reasonable oral strategy with a reasonably tolerated toxicity profile. The cost of treatment and durability of response should be incorporated into the discussion as part of the overall medical decision-making.

Vorinostat in patients with resistant BRAFV600E mutated advanced melanoma: a proof of concept study

The clinical benefit of treatment with BRAF- and MEK-inhibitors in melanoma is limited due to resistance associated with emerging secondary mutations. Preclinical and clinical studies have shown that short-term treatment with the HDAC inhibitor vorinostat can eliminate cells harboring these secondary mutations causing resistance. This proof of concept study is to determine the efficacy of sequential treatment with vorinostat and BRAFi/MEKi in resistant BRAF^V600E mutant melanoma. The primary aim is demonstrating anti-tumor response of progressive lesions according to RECIST 1.1. Secondary end points are to determine that emerging resistant clones with a secondary mutation in the MAPK pathway can be detected in circulating tumor DNA and purged by short-term vorinostat treatment. Exploratory end points include pharmacokinetic, pharmacodynamic and pharmacogenetic analyses (NCT02836548).

The choice for the optimal therapy in advanced biliary tract cancers: Chemotherapy, targeted therapies or immunotherapy

Biliary tract cancers (BTCs) represent a heterogeneous group that includes intrahepatic cholangiocarcinomas (CCAs), perihilar-CCAs or Klatskin tumors, extrahepatic-CCAs, and gallbladder adenocarcinoma. These entities have distinct demographics, risk factors, clinical presentation, and molecular characteristics. In advanced BTCs, the recommendations are mainly supporting a doublet chemotherapy regimen using cisplatin/gemcitabine (CisGem) with a 5-year overall survival rate close to 5% and median overall survival (mOS) of less than a year. The lack of overall efficacy stresses the need for personalized therapies. Recently, whole-genome and transcriptome sequencing highlighted the diversity of BTCs' subtypes. Distinct genetic alterations were retrieved according to the localization, with a high rate of potentially actionable alterations. Targeted therapies and immunotherapy have since then been tested for BTCs, trying to propose a more personalized treatment. This review describes the different therapeutic options, validated and in development, for patients with advanced BTCs.

MEK1/2 as a Therapeutic Target in Sickle Cell Disease

Identification of novel therapeutic targets has improved diagnostics and treatment of many diseases. Many innovative treatment strategies have been developed based on the newly identified biomarkers and key molecules. Most of the research focused on ways to manipulate signaling pathways by activating or suppressing them, validate new therapeutic targets for treatment, and epigenetic treatment of diseases. With the identification of aberrations in multiple growth pathways, the focus then shifted to the small molecules involved in these pathways for targeted therapy. In this communication/short review, we highlight the importance of identification of abnormal activation of the mitogen-activated protein kinase (MAPK), ERK1/2, and its upstream mediator MEK1/2, in erythrocytes in patients with sickle cell disease (SCD) critical for the adhesive interactions of these cells with the endothelium, and leukocytes promoting circulatory obstruction leading to tissue ischemia and infraction. We also discuss how targeting this signaling cascade with MEK1/2 inhibitors can reverse acute vasoocclusive crises in SCD.

A Comprehensive Review on MAPK: A Promising Therapeutic Target in Cancer

The mitogen-activated protein kinase (MAPK) pathway is an important bridge in the switch from extracellular signals to intracellular responses. Alterations of signaling cascades are found in various diseases, including cancer, as a result of genetic and epigenetic changes. Numerous studies focused on both the homeostatic and the pathologic conduct of MAPK signaling; however, there is still much to be deciphered in terms of regulation and action models in both preclinical and clinical research. MAPK has implications in the response to cancer therapy, particularly the activation of the compensatory pathways in response to experimental MAPK inhibition. The present paper discusses new insights into MAPK as a complex cell signaling pathway with roles in the sustenance of cellular normal conduit, response to cancer therapy, and activation of compensatory pathways. Unfortunately, most MAPK inhibitors trigger resistance due to the activation of compensatory feed-back loops in tumor cells and tumor microenvironment components. Therefore, novel combinatorial therapies have to be implemented for cancer management in order to restrict the possibility of alternative pathway activation, as a perspective for developing novel therapies based on integration in translational studies.