Impact of depth of response on survival in patients treated with cobimetinib ± vemurafenib: pooled analysis of BRIM-2, BRIM-3, BRIM-7 and coBRIM

The outcome in patients with BRAF-mutated metastatic melanoma treated with anti-programmed death receptor-1 monotherapy or targeted therapy in the real-world setting

BACKGROUND

Immunotherapy and targeted therapy are currently two alternative backbones in the therapy of BRAF-mutated malignant melanoma. However, predictive biomarkers that would help with treatment selection are lacking.

METHODS

This retrospective study investigated outcomes of anti-programmed death receptor-1 monotherapy and targeted therapy in the first-line setting in patients with metastatic BRAF-mutated melanoma, focusing on clinical and laboratory parameters associated with treatment outcome.

RESULTS

Data from 174 patients were analysed. The median progression-free survival (PFS) was 17.0 months (95% CI; 8-39) and 12.5 months (95% CI; 9-14.2) for immunotherapy and targeted therapy, respectively. The 3-year PFS rate was 39% for immunotherapy and 25% for targeted therapy. The objective response rate was 72% and 51% for targeted therapy and immunotherapy. The median overall (OS) survival for immunotherapy has not been reached and was 23.6 months (95% CI; 16.1-38.2) for targeted therapy, with a 3-year survival rate of 63% and 40%, respectively. In a univariate analysis, age < 70 years, a higher number of metastatic sites, elevated serum LDH and a neutrophil-lymphocyte ratio above the cut-off value were associated with inferior PFS regardless of the therapy received, but only serum LDH level and the presence of lung metastases remained significant predictors of PFS in a multivariate analysis.

CONCLUSIONS

Present real-world data document the high effectiveness of immunotherapy and targeted therapy. Although targeted therapy had higher response rates, immunotherapy improved PFS and OS. While the prognostic value of LDH was confirmed, the potential use of blood cell count-derived parameters to predict outcomes needs further investigation.

Triplet Strategies in Metastatic Clear Cell Renal Cell Carcinoma: A Worthy Option in the First-Line Setting?

Significant strides have been made in the frontline treatment of patients with advanced clear cell renal cell carcinoma (ccRCC). There are multiple standard-of-care doublet regimens consisting of either the combined dual immune checkpoint inhibitors, ipilimumab and nivolumab, or combinations of a vascular endothelial growth factor receptor tyrosine kinase inhibitor and an immune checkpoint inhibitor. Currently, there is an emergence of clinical trials examining triplet combinations. In COSMIC-313, a randomized phase III trial for patients with untreated advanced ccRCC, the triplet combination of ipilimumab, nivolumab, and cabozantinib was compared with a contemporary control arm of ipilimumab and nivolumab. While patients receiving the triplet regimen demonstrated improved progression-free survival, these patients also experienced greater toxicity and the overall survival data are still maturing. In this article, we discuss the role of doublet therapy as standard of care, the current data available for the promise of triplet therapy, the rationale to continue pursuing trials with triplet combinations, and factors for clinicians and patients to consider when choosing among frontline treatments. We present ongoing trials with an adaptive design that may serve as alternative methods for escalating from doublet to triplet regimens in the frontline setting and explore clinical factors and emerging predictive biomarkers (both baseline and dynamic) that may guide future trial design and frontline treatment for patients with advanced ccRCC.

Long-Term Real-World Outcomes and Safety of Vemurafenib and Vemurafenib + Cobimetinib Therapy in Patients with BRAF-Mutated Melanoma

BACKGROUND

Combined treatment with BRAFi and/or MEK inhibitors (MEKi) improves outcomes in advanced melanoma patients in comparison with monotherapy.

OBJECTIVE

We aim to report real-world treatment efficacy and safety of vemurafenib (V) and vemurafenib + cobimetinib (V + C) from 10 years of practice.

PATIENTS AND METHODS

A total of 275 consecutive patients with unresectable or metastatic BRAF mutated melanoma started first-line V or V + C treatment between 1 October 2013 and 31 December 2020. Survival analyses were performed using the Kaplan-Meier method, and Log-rank and Chi-square tests were used for comparison between groups.

RESULTS

The estimated median overall survival (mOS) was 10.3 months in the V group, and 12.3 months in the V + C group (p = 0.0005; HR = 1.58, 95% CI 1.2-2.1), although the latter group of patients had lactate dehydrogenase elevated numerically more often. Estimated median progression-free survival (mPFS) was 5.5 months in the V group, and 8.3 months in the V + C group (p = 0.0002; HR = 1.62, 95% CI 1.3-2.1). Complete response, partial response, stable disease, and progressive disease as best responses were recorded in the V/V + C groups in 7%/10%, 52%/46%, 26%/28%, and 15%/16% of patients, respectively. The numbers of patients with any grade of adverse effects were similar in both groups.

CONCLUSIONS

We confirmed significant improvement in the mOS and mPFS of unresectable and/or metastatic BRAF mutated-melanoma patients treated outside clinical trials with V + C as compared with V, with no major increase in toxicity for the combination.

Potential Biomarkers of Skin Melanoma Resistance to Targeted Therapy—Present State and Perspectives

Simple Summary

Around 5–10% of advanced melanoma patients progress early on anti-BRAF targeted therapy and 20–30% respond only with the stabilization of the disease. Presumably, these patients could benefit more from first-line immunotherapy. Resistance to BRAF/MEK inhibitors is generated by genetic and non-genetic factors inherent to a tumor or acquired during therapy. Some of them are well documented as a cause of treatment failure. They are potential predictive markers that could improve patients’ selection for both standard and also alternative therapy as some of them have therapeutic potential. Here, a summary of the most promising predictive and therapeutic targets is presented. This up-to-date knowledge may be useful for further study on implementing more accurate genetic/molecular tests in melanoma treatment.

Abstract

Melanoma is the most aggressive skin cancer, the number of which is increasing worldwide every year. It is completely curable in its early stage and fatal when spread to distant organs. In addition to new therapeutic strategies, biomarkers are an important element in the successful fight against this cancer. At present, biomarkers are mainly used in diagnostics. Some biological indicators also allow the estimation of the patient’s prognosis. Still, predictive markers are underrepresented in clinics. Currently, the only such indicator is the presence of the V600E mutation in the BRAF gene in cancer cells, which qualifies the patient for therapy with inhibitors of the MAPK pathway. The identification of response markers is particularly important given primary and acquired resistance to targeted therapies. Reliable predictive tests would enable the selection of patients who would have the best chance of benefiting from treatment. Here, up-to-date knowledge about the most promising genetic and non-genetic resistance-related factors is described. These are alterations in MAPK, PI3K/AKT, and RB signaling pathways, e.g., due to mutations in NRAS, RAC1, MAP2K1, MAP2K2, and NF1, but also other changes activating these pathways, such as the overexpression of HGF or EGFR. Most of them are also potential therapeutic targets and this issue is also addressed here.

Combined BRAF-Targeted Therapy with Immunotherapy in BRAF-Mutated Advanced Melanoma Patients

PURPOSE OF REVIEW

To review evidence on the efficacy and safety of combined BRAF-targeted therapy and immune checkpoint inhibitors in patients with BRAF-mutated metastatic melanoma.

RECENT FINDINGS

Programmed death-1 pathway inhibitors administered with BRAF/MEK inhibitors showed promising anti-tumour activity in BRAF-mutated advanced melanoma and were investigated for safety and efficacy in three large international clinical trials. Although, in two out of those three randomized phase III studies, progression-free survival (PFS) did not reach statistical significance, results showed that duration of response (DOR) and overall survival (OS) were improved using combined therapy, sustaining the scientific rationale for its use at least in a subset of metastatic melanomas. However, the frequent occurrence of autoimmunity-induced toxicities should be considered since it is limiting the continuity and the wide application of these regimens. Novel treatment modalities combining targeted therapy with checkpoint inhibitors require further clinical investigation and elucidation of their effect on the immune system and cancer cell modulation.

5-Year Outcomes with Cobimetinib plus Vemurafenib in BRAFV600 Mutation-Positive Advanced Melanoma: Extended Follow-up of the coBRIM Study

PURPOSE

The randomized phase III coBRIM study (NCT01689519) demonstrated improved progression-free survival (PFS) and overall survival (OS) with addition of cobimetinib to vemurafenib compared with vemurafenib in patients with previously untreated BRAFV600 mutation-positive advanced melanoma. We report long-term follow-up of coBRIM, with at least 5 years since the last patient was randomized.

PATIENTS AND METHODS

Eligible patients were randomized 1:1 to receive either oral cobimetinib (60 mg once daily on days 1-21 in each 28-day cycle) or placebo in combination with oral vemurafenib (960 mg twice daily).

RESULTS

495 patients were randomized to cobimetinib plus vemurafenib (n = 247) or placebo plus vemurafenib (n = 248). Median follow-up was 21.2 months for cobimetinib plus vemurafenib and 16.6 months for placebo plus vemurafenib. Median OS was 22.5 months (95% CI, 20.3-28.8) with cobimetinib plus vemurafenib and 17.4 months (95% CI, 15.0-19.8) with placebo plus vemurafenib; 5-year OS rates were 31% and 26%, respectively. Median PFS was 12.6 months (95% CI, 9.5-14.8) with cobimetinib plus vemurafenib and 7.2 months (95% CI, 5.6-7.5) with placebo plus vemurafenib; 5-year PFS rates were 14% and 10%, respectively. OS and PFS were longest in patients with normal baseline lactate dehydrogenase levels and low tumor burden, and in those achieving complete response. The safety profile remained consistent with previously published reports.

CONCLUSIONS

Extended follow-up of coBRIM confirms the long-term clinical benefit and safety profile of cobimetinib plus vemurafenib compared with vemurafenib monotherapy in patients with BRAFV600 mutation-positive advanced melanoma.

KEYNOTE-022 part 3: a randomized, double-blind, phase 2 study of pembrolizumab, dabrafenib, and trametinib in BRAF-mutant melanoma

Background

In the KEYNOTE-022 study, pembrolizumab with dabrafenib and trametinib (triplet) improved progression-free survival (PFS) versus placebo with dabrafenib and trametinib (doublet) without reaching statistical significance. Mature results on PFS, duration of response (DOR), and overall survival (OS) are reported.

Methods

The double-blind, phase 2 part of KEYNOTE-022 enrolled patients with previously untreated BRAF^V600E/K-mutated advanced melanoma from 22 sites in seven countries. Patients were randomly assigned 1:1 to intravenous pembrolizumab (200 mg every 3 weeks) or placebo plus dabrafenib (150 mg orally two times per day) and trametinib (2 mg orally one time a day). Primary endpoint was PFS. Secondary endpoints were objective response rate, DOR, and OS. Efficacy was assessed in the intention-to-treat population, and safety was assessed in all patients who received at least one dose of study drug. This analysis was not specified in the protocol.

Results

Between November 30, 2015 and April 24, 2017, 120 patients were randomly assigned to triplet (n=60) or doublet (n=60) therapy. With 36.6 months of follow-up, median PFS was 16.9 months (95% CI 11.3 to 27.9) with triplet and 10.7 months (95% CI 7.2 to 16.8) with doublet (HR 0.53; 95% CI 0.34 to 0.83). With triplet and doublet, respectively, PFS at 24 months was 41.0% (95% CI 27.4% to 54.2%) and 16.3% (95% CI 8.1% to 27.1%); median DOR was 25.1 months (95% CI 14.1 to not reached) and 12.1 months (95% CI 6.0 to 15.7), respectively. Median OS was not reached with triplet and was 26.3 months with doublet (HR 0.64; 95% CI 0.38 to 1.06). With triplet and doublet, respectively, OS at 24 months was 63.0% (95% CI 49.4% to 73.9%) and 51.7% (95% CI 38.4% to 63.4%). Grade 3–5 treatment-related adverse events (TRAEs) occurred in 35 patients (58%, including one death) receiving triplet and 15 patients (25%) receiving doublet.

Conclusion

In BRAF^V600E/K-mutant advanced melanoma, pembrolizumab plus dabrafenib and trametinib substantially improved PFS, DOR, and OS with a higher incidence of TRAEs. Interpretation of these results is limited by the post hoc nature of the analysis.

Relationship Between Apparent Systemic Clearance of Vemurafenib and Toxicity in Patients With Melanoma

Vemurafenib, a B rapidly accelerated fibrosarcoma inhibitor, is commonly used in combination of cobimetinib for the treatment of melanoma. In the current study, we evaluated the relationship between vemurafenib exposure, as measured by the estimated apparent clearance (CL_B ) at steady state and any grade ≥3 toxicity, grade ≥3 skin rash, or toxicity requiring dose modification using pooled data from 3 prospective clinical trials involving 898 patients. A total of 69% had any grade ≥3 toxicity; grade ≥3 skin rash in 15% and 47% had a dose reduction/interruption or cessation. The median vemurafenib CL_B was 1.35 L/h (interquartile range, 1.15-1.65 L/h). Lower vemurafenib CL_B was significantly associated with an increased risk of grade ≥3 toxicity (hazard ratio [HR], 0.62; P < .001), grade ≥3 rash (HR, 0.29; P < .001), and adverse events requiring vemurafenib dose reduction/interruption or cessation (HR, 0.5; P < .001). When the patients were divided into 3 groups based on the vemurafenib CL_B thresholds, those with low CL_B (<1.22 L/h) had significantly increased incidence of any grade ≥3 toxicity or skin rash or dose adjustment, interruption, or cessation at 12 months and at day 28 when compared to those with medium (≥1.22 and <1.55 L/h) or high (>1.55 L/h) vemurafenib CL_B . In conclusion, the estimated CL_B of vemurafenib is associated with severe toxicities and dose adjustment or cessation, suggesting that an early estimation of vemurafenib exposure may be useful in identifying patients at risk of experiencing toxicity.

NGS Analysis of Liquid Biopsy (LB) and Formalin-Fixed Paraffin-Embedded (FFPE) Melanoma Samples Using Oncomine™ Pan-Cancer Cell-Free Assay

Next-generation sequencing (NGS) in liquid biopsies may contribute to the diagnosis, monitoring, and personalized therapy of cancer through the real-time detection of a tumor’s genetic profile. There are a few NGS platforms offering high-sensitivity sequencing of cell-free DNA (cfDNA) samples. The aim of this study was to evaluate the Ion AmpliSeq HD Technology for targeted sequencing of tumor and liquid biopsy samples from patients with fourth-stage melanoma. Sequencing of 30 samples (FFPE tumor and liquid biopsy) derived from 14 patients using the Oncomine™ Pan-Cancer Cell-Free Assay was performed. The analysis revealed high concordance between the qPCR and NGS results of the BRAF mutation in FFPE samples (91%), as well as between the FFPE and liquid biopsy samples (91%). The plasma-tumor concordance of the non-BRAF mutations was 28%. A total of 17 pathogenic variants in 14 genes (from 52-gene panel), including TP53, CTNNB1, CCND1, MET, MAP2K1, and GNAS, were identified, with the CTNNB1^S45F variant being the most frequent. A positive correlation between the LDH level and cfDNA concentration as well as negative correlation between the LDH level and time to progression was confirmed in a 22-patient cohort. The analysis showed both the potential and limitations of liquid biopsy genetic profiling using HD technology and the Ion Torrent platform.

Synthesis, inverse docking-assisted identification and in vitro biological characterization of Flavonol-based analogs of fisetin as c-Kit, CDK2 and mTOR inhibitors against melanoma and non-melanoma skin cancers

Due to hurdles, including resistance, adverse effects, and poor bioavailability, among others linked with existing therapies, there is an urgent unmet need to devise new, safe, and more effective treatment modalities for skin cancers. Herein, a series of flavonol-based derivatives of fisetin, a plant-based flavonoid identified as an anti-tumorigenic agent targeting the mammalian targets of rapamycin (mTOR)-regulated pathways, were synthesized and fully characterized. New potential inhibitors of receptor tyrosine kinases (c-KITs), cyclin-dependent kinase-2 (CDK2), and mTOR, representing attractive therapeutic targets for melanoma and non-melanoma skin cancers (NMSCs) treatment, were identified using inverse-docking, in vitro kinase activity and various cell-based anticancer screening assays. Eleven compounds exhibited significant inhibitory activities greater than the parent molecule against four human skin cancer cell lines, including melanoma (A375 and SK-Mel-28) and NMSCs (A431 and UWBCC1), with IC50 values ranging from 0.12 to < 15 μM. Seven compounds were identified as potentially potent single, dual or multi-kinase c-KITs, CDK2, and mTOR kinase inhibitors after inverse-docking and screening against twelve known cancer targets, followed by kinase activity profiling. Moreover, the potent compound F20, and the multi-kinase F9 and F17 targeted compounds, markedly decreased scratch wound closure, colony formation, and heightened expression levels of key cancer-promoting pathway molecular targets c-Kit, CDK2, and mTOR. In addition, these compounds downregulated Bcl-2 levels and upregulated Bax and cleaved caspase-3/7/8 and PARP levels, thus inducing apoptosis of A375 and A431 cells in a dose-dependent manner. Overall, compounds F20, F9 and F17, were identified as promising c-Kit, CDK2 and mTOR inhibitors, worthy of further investigation as therapeutics, or as adjuvants to standard therapies for the control of melanoma and NMSCs.

Long-Term Outcomes in BRAF-Mutated Melanoma Treated with Combined Targeted Therapy or Immune Checkpoint Blockade: Are We Approaching a True Cure?

Approximately 50% of all melanomas harbor an activating BRAF mutation. In patients suffering from an advanced melanoma with such a somatic alteration, combined targeted therapy with a BRAF and MEK inhibitor can be applied to significantly increase the survival probability. Nevertheless, resistance mechanisms, as well as negative predictive biomarkers (elevated lactate dehydrogenase levels, high number of metastatic organ disease sites, brain metastasis), remain a major problem in treating melanoma patients. Recently, a landmark overall survival (OS) rate of 34% after 5 years of combined targeted therapy in treatment-naïve patients was reported. On the other hand, patients harboring a BRAF mutation and receiving first-line immune checkpoint blockade with ipilimumab plus nivolumab showed a 5-year OS rate of 60%. As indicated by these data, long-term survival can be reached in melanoma patients but it remains unclear if this is equivalent to reaching a true cure for metastatic melanoma. In this review, we summarize the recent results for combined targeted therapy and immunotherapy in advanced melanoma harboring an activating BRAF mutation and discuss the impact of baseline characteristics on long-term outcome.

Genetic Profiling of Advanced Melanoma: Candidate Mutations for Predicting Sensitivity and Resistance to Targeted Therapy

BACKGROUND

Molecularly targeted therapy has revolutionized the treatment of advanced melanoma. However, despite its high efficiency, a majority of patients experience relapse within 1 year of treatment because of acquired resistance, and approximately 10-25% patients gain no benefit from these agents owing to intrinsic resistance. This is mainly caused by the genetic heterogeneity of melanoma cells.

OBJECTIVE

We aimed to validate the predictive significance of selected genes in advanced melanoma patients before treatment with BRAF/MEK inhibitors.

PATIENTS AND METHODS

Archival DNA derived from 37 formalin-fixed paraffin-embedded pre-treatment advanced melanoma samples of patients treated with targeted therapy was used for next-generation sequencing analysis using the Ion Torrent platform. The AmpliSeq Custom Panel comprised coding sequences or hot spots of 23 melanoma genes: ATM, BRAF, CDK4, CDKN2A, CTNNB1, EGFR, HOXD8, HRAS, IDH1, KIT, KRAS, MAP3K8, MAP2K1, MAP2K2, MITF, MYC, NF1, NRAS, PAX5, PIK3R1, PTEN, RAC1, and RB1. The sequences were evaluated for genomic alterations and further validated using Sanger sequencing.

RESULTS

Our analysis revealed non-BRAF genetic alterations in 28 out of 37 samples (75.7%). Genetic changes were identified in PTEN, CDK4, CDKN2A, CTNNB1, EGFR, HOXD8, HRAS, KIT, MAP2K1, MAP2K2, MITF, MYC, NF1, PAX5, RAC1, and RB1. Fifteen known pathogenic mutations (single nucleotide variants or indels) and 11 variants of unknown significance were detected. Statistical analysis revealed an association between the presence of pathogenic mutations and time to progression during treatment with combination therapy.

CONCLUSIONS

Pathogenic mutations identified by gene panel sequencing have potential predictive value for targeted therapy of melanoma and are worth further validation in a larger series of cases. The role of some known mutations (e.g. CDK4R24, PTEN c.801 + 1G > A, CTNNB1S45F) as well as variants of unknown significance identified in this study (e.g. MITFR316K, KITG498S) in the generation of resistance to BRAF/MEK inhibitors should be further investigated.

Identifying the optimum first-line therapy in BRAF-mutant metastatic melanoma

Introduction: The emergence of molecularly targeted agents and immune checkpoint inhibitors has positively revolutionized the management and prognosis of BRAF-mutant metastatic melanoma. However, the availability of both therapeutic options, with their pros and cons, rationally triggered clinical considerations for the optimum frontline and subsequent treatment decisions.Areas covered: Here, we debate all approved therapies in patients with BRAF-mutant metastatic melanoma evaluating their efficacy and safety based on their pivotal trials. With prospective randomized data pending, retrospective comparisons of BRAF/MEK versus immune checkpoint inhibitors are reviewed to recognize any advantage between these two alternatives and to optimize their implementation. Preclinical and early clinical results of combining concurrently or sequentially targeted therapy and immunotherapy are also discussed.Expert opinion: BRAF/MEK inhibitors produce rapid and deep responses and should be included in first-line approaches, particularly in cases with aggressive and bulky disease, while single or double checkpoint inhibition lead to more durable responses and could be involved either in frontline treatment of BRAF-mutant melanoma with less unfavorable characteristics or in maintenance after initial targeted induction or in future immune/targeted regimens for high-risk groups. Data from ongoing trials directly comparing or combining these strategies are expected to update their role in a more individualized basis.

Relationship between vemurafenib plasma concentrations and survival outcomes in patients with advanced melanoma

Purpose To validate a plasma vemurafenib steady-state trough concentration (C_ss,_min) threshold that predicts survival outcomes of patients with BrafV⁶⁰⁰ mutated melanoma.

METHODS

A pooled analysis of individual patient data from two advanced melanoma trials involving vemurafenib ± cobimetinib therapy was performed. Day 23 was chosen as the landmark time when steady-state concentration reached. Optimal C_ss,_min threshold was determined via assessment of discriminative performance and model fitting. Association between vemurafenib C_ss,_min and survival was modelled using Cox proportional hazards regression.

RESULTS

Vemurafenib plasma concentration data were available for 402 patients who were on stable dose for the first 3 weeks. When compared to a previously described plasma vemurafenib C_ss,_min threshold of 42 mg/L, we identified that a cutoff concentration of 50 mg/L by day 23 was strongly associated with progression-free survival and overall survival. The association remained statistically significant after adjusting for important clinical confounding variables. Sub-group analysis showed that while the addition of cobimetinib resulted in a lower day 23 plasma vemurafenib C_ss,_min, the threshold was still associated with overall survival and not in the monotherapy cohort.

CONCLUSION

A plasma vemurafenib C_ss,_min threshold of 50 mg/L is strongly associated with survival outcomes in patients with advanced melanoma. This new threshold needs to be validated prospectively in future studies.