The nature and management of metastatic melanoma after progression on BRAF inhibitors: effects of extended BRAF inhibition

Checkpoint Inhibition in Addition to Dabrafenib/Trametinib for BRAFV600E-Mutated Anaplastic Thyroid Carcinoma

Background: The dabrafenib plus trametinib combination (DT) has revolutionized the treatment of BRAFV600E-mutated anaplastic thyroid carcinoma (BRAFm-ATC). However, patients eventually develop resistance and progress. Single-agent anti-PD-1 inhibitor spartalizumab has shown a median overall survival (mOS) of 5.9 months. Combination of immunotherapy with BRAF/MEK inhibitors (BRAF/MEKi) seems to improve outcomes compared with BRAF/MEKi alone, although no direct comparison is available. BRAF-targeted therapy before surgery (neoadjuvant approach) has also shown improvement in survival. We studied the efficacy and safety of DT plus pembrolizumab (DTP) compared with current standard-of-care DT alone as an initial treatment, as well as in the neoadjuvant setting. Methods: Retrospective single-center study of patients with BRAFm-ATC treated with first-line BRAF-directed therapy between January 2014 and March 2023. Three groups were evaluated: DT, DTP (pembrolizumab added upfront or at progression), and neoadjuvant (DT before surgery, and pembrolizumab added before or after surgery). The primary endpoint was mOS between DT and DTP. Secondary endpoints included median progression-free survival (mPFS) and response rate with DT versus DTP as initial treatments, and the exploratory endpoint was mOS in the neoadjuvant group. Results: Seventy-one patients were included in the primary analysis: n = 23 in DT and n = 48 in DTP. Baseline demographics were similar between groups, including the presence of metastatic disease at start of treatment (p = 0.427) and prior treatments with surgery (p = 0.864) and radiation (p = 0.678). mOS was significantly longer with DTP (17.0 months [confidence interval CI, 11.9-22.1]) compared with DT alone (9.0 months [CI, 4.5-13.5]), p = 0.037. mPFS was also significantly improved with DTP as the initial treatment (11.0 months [CI, 7.0-15.0]) compared with DT alone (4.0 months [CI, 0.7-7.3]), p = 0.049. Twenty-three patients were in the exploratory neoadjuvant group, where mOS was the longest (63.0 months [CI, 15.5-110.5]). No grade 5 adverse events (AEs) occurred in all three cohorts, and 32.4% had immune-related AEs, most frequently hepatitis and colitis. Conclusions: Our results show that in BRAFm-ATC, addition of pembrolizumab to dabrafenib/trametinib may significantly prolong survival. Surgical resection of the primary tumor after initial BRAF-targeted therapy in selected patients may provide further survival benefit. However, conclusions are limited by the retrospective nature of the study. Additional prospective data are needed to confirm this observation.

Dabrafenib-Trametinib and Radiotherapy for Oligoprogressive BRAF Mutant Advanced Melanoma

The clinical management of metastatic melanoma has been changed by BRAF (BRAFi) and MEK inhibitors (MEKi), which represent a standard treatment for BRAF-mutant melanoma. In oligoprogressive melanoma patients with BRAF mutations, target therapy can be combined with loco-regional radiotherapy (RT). However, the association of BRAF/MEK inhibitors and RT needs to be carefully monitored for potential increased toxicity. Despite the availability of some reports regarding the tolerability of RT + target therapy, data on simultaneous RT and BRAFi/MEKi are limited and mostly focused on the BRAFi vemurafenib. Here, we report a series of metastatic melanoma patients who received fractioned RT regimens for oligoprogressive disease in combination with the BRAFi dabrafenib and the MEKi trametinib, which have continued beyond progression. None of the cases developed relevant adverse events while receiving RT or interrupted dabrafenib and trametinib administration. These cases suggest that a long period of dabrafenib/trametinib interruption during radiotherapy for oligoprogressive disease can be avoided. Prospective trials are warranted to assess the efficacy and safety of the contemporary administration of BRAF/MEK inhibitors and radiotherapy for oligoprogressive disease.

Novel therapeutic strategy for melanoma based on albendazole and the CDK4/6 inhibitor palbociclib

Although an increasing number of patients benefit from immunotherapy and targeted therapies, melanoma remains incurable with increasing incidence. Drug repositioning and repurposing is an alternative strategy to discover and develop novel anticancer drugs or combined therapeutic regimens. In this study, we demonstrated that albendazole (ABZ), an Food and Drug Administration (FDA)-approved broad-spectrum antiparasitic agent, significantly inhibits the proliferation of melanoma cells in vitro and in vivo. RNA sequencing and flow cytometry analysis revealed that ABZ arrests melanoma cells at the G2/M phase of the cell cycle and induces cell apoptosis. More importantly, the CDK4/6 inhibitor palbociclib, as a member of the first and only class of highly specific CDK inhibitors approved for cancer treatment to date, showed significant synergistic effects with ABZ treatment in melanoma cells and mouse models. Taken together, we revealed a previously unappreciated function of ABZ in antimelanoma proliferation by inducing cell cycle arrest and apoptosis and provided a novel combined therapeutic regimen of ABZ plus CDK4/6 inhibitor treatment in melanoma.

Pulmonary metastatic melanoma: current state of diagnostic imaging and treatments

Melanoma is the deadliest form of skin cancer with an estimated incidence of over 160,000 cases annually and about 41,000 melanoma-related deaths per year worldwide. Malignant melanoma (MM) primarily occurs in the skin but has been described in other organs. Although the respiratory system is generally afflicted by tumors such as lung cancer, it is also rarely affected by primary MM. The estimated incidence of pulmonary MM of the lung accounts for 0.01% of all primary lung tumors. The current understanding of pulmonary MM of the lung pathophysiology and its management are not well established. We aim to survey current clinical modalities with a focus on diagnostic imaging and therapeutic intervention to guide providers in the management of patients with a high index of suspicion.

Dabrafenib plus trametinib in patients with BRAFV600E-mutant low-grade and high-grade glioma (ROAR): a multicentre, open-label, single-arm, phase 2, basket trial

BACKGROUND

Effective treatments are needed to improve outcomes for high-grade glioma and low-grade glioma. The activity and safety of dabrafenib plus trametinib were evaluated in adult patients with recurrent or progressive BRAF^V600E mutation-positive high-grade glioma and low-grade glioma.

METHODS

This study is part of an ongoing open-label, single-arm, phase 2 Rare Oncology Agnostic Research (ROAR) basket trial at 27 community and academic cancer centres in 13 countries (Austria, Belgium, Canada, France, Germany, Italy, Japan, the Netherlands, Norway, South Korea, Spain, Sweden, and the USA). The study enrolled patients aged 18 years or older with an Eastern Cooperative Oncology Group performance status of 0, 1, or 2. Patients with BRAF^V600E mutation-positive high-grade glioma and low-grade glioma received dabrafenib 150 mg twice daily plus trametinib 2 mg once daily orally until unacceptable toxicity, disease progression, or death. In the high-grade glioma cohort, patients were required to have measurable disease at baseline using the Response Assessment in Neuro-Oncology high-grade glioma response criteria and have been treated previously with radiotherapy and first-line chemotherapy or concurrent chemoradiotherapy. Patients with low-grade glioma were required to have measurable non-enhancing disease (except pilocytic astrocytoma) at baseline using the Response Assessment in Neuro-Oncology low-grade glioma criteria. The primary endpoint, in the evaluable intention-to-treat population, was investigator-assessed objective response rate (complete response plus partial response for high-grade glioma and complete response plus partial response plus minor response for low-grade glioma). This trial is ongoing, but is closed for enrolment, NCT02034110.

FINDINGS

Between April 17, 2014, and July 25, 2018, 45 patients (31 with glioblastoma) were enrolled into the high-grade glioma cohort and 13 patients were enrolled into the low-grade glioma cohort. The results presented here are based on interim analysis 16 (data cutoff Sept 14, 2020). In the high-grade glioma cohort, median follow-up was 12·7 months (IQR 5·4-32·3) and 15 (33%; 95% CI 20-49) of 45 patients had an objective response by investigator assessment, including three complete responses and 12 partial responses. In the low-grade glioma cohort, median follow-up was 32·2 months (IQR 25·1-47·8). Nine (69%; 95% CI 39-91) of 13 patients had an objective response by investigator assessment, including one complete response, six partial responses, and two minor responses. Grade 3 or worse adverse events were reported in 31 (53%) patients, the most common being fatigue (five [9%]), decreased neutrophil count (five [9%]), headache (three [5%]), and neutropenia (three [5%]).

INTERPRETATION

Dabrafenib plus trametinib showed clinically meaningful activity in patients with BRAF^V600E mutation-positive recurrent or refractory high-grade glioma and low-grade glioma, with a safety profile consistent with that in other indications. BRAF^V600E testing could potentially be adopted in clinical practice for patients with glioma.

FUNDING

Novartis.

Treatment beyond progression and locoregional approaches in selected patients with BRAF-mutated metastatic melanoma

The clinical management of BRAF-mutated metastatic melanoma had an important turning point after the introduction of the targeted therapy. Despite the efficacy and good tolerability of this treatment, the development of resistance mechanisms causes disease progression. The aim of this review is to investigate the role of treatment beyond progression and locoregional approaches in BRAF-mutated metastatic melanoma and provide oncologists dealing with this malignancy a useful road map on when and why to choose this strategy.

The article is structured in the form of a narrative review reporting the most significant studies on the subject. Most of the available articles are represented by retrospective studies and case reports, leading to limitations in the final interpretations. Nevertheless, a correct analysis of the selected studies allows the drawing of some conclusions. In well-selected cases, treatment beyond progression could play an important role in the treatment sequence of patients with BRAF-mutated advanced melanoma and would seem to produce good disease control rates and positive survival outcomes. A careful evaluation of the radiological examinations and laboratory tests, based on the clinical conditions, allows the identification of which patients can benefit from this strategy. Such patients are those who, at the time of progression, have favourable features such as a lower performance status according to Eastern Cooperative Oncology Group (ECOG-PS), normal lactate dehydrogenase levels and lower disease burden. The clinical benefit is also consolidated by the addition of locoregional approaches. Locoregional approaches can include electrochemotherapy, radiotherapy or surgery, and their use provides local disease control and a better quality of life for patients.

Phase I/II trial of concurrent extracranial palliative radiation therapy with Dabrafenib and Trametinib in metastatic BRAF V600E/K mutation-positive cutaneous Melanoma

Background

Concurrent treatment with BRAF inhibitors and palliative radiation therapy (RT) could be associated with increased toxicity, especially skin toxicity. Current Eastern Cooperative Oncology Group (ECOG) consensus guideline recommend ceasing BRAF inhibitors during RT. There is a lack of data regarding concurrent RT with combined BRAF and MEK inhibitors. This single-arm phase I/II trial was designed to assess the safety and tolerability of palliative RT with concurrent Dabrafenib and Trametinib in patients with BRAF-mutant metastatic melanoma.

Materials and methods

Patients received Dabrafenib and Trametinib before and during palliative RT to soft tissue, nodal or bony metastases. The RT dose was escalated stepwise during the study period. Toxicity data including clinical photographs of the irradiated area was collected for up to 12 months following completion of RT.

Results

Between June 2016 to October 2019, ten patients were enrolled before the study was stopped early due to low accrual rate. Six patients were treated at level 1 (20 Gy in 5 fractions, any location) and 4 patients at level 2a (30 Gy in 10 fractions with no abdominal viscera exposed). All alive patients completed one year of post-RT follow-up. Of the 82 adverse events (AEs) documented, the majority (90%) were grade 1 and 2. Eight grade 3 events (10%) occurred in five patients, only one was treatment-related (grade 3 fever due to Dabrafenib and Trametinib). No patients experienced grade 3 or 4 RT related toxicities, including skin toxicities. One serious AE was documented in relation to a grade 3 fever due to Dabrafenib and Trametinib requiring hospitalisation.

Conclusions

The lack of grade 3 and 4 RT-related toxicities in our study suggests that Dabrafenib and Trametinib may be continued concurrently during fractionated non-visceral palliative RT to extracranial sites.

Treatment of Advanced Metastatic Melanoma

The introduction in clinical practice of new drug compounds both targeted therapies anti-BRAF and checkpoint inhibitors have largely improved our potential to manage advanced metastatic melanoma patients. This has led to a significant improvement in terms of response rates and particularly in the overall survival (OS). The long-term results of trials with follow-up data of patients treated with targeted or immunotherapies reported median OS rates around 24 months, with 5-year survival rates around 35-40%. As to the drugs currently available and reimbursed by the Italian National Health System, 3 combinations of anti-BRAF/anti-MEK inhibitors are available (dabrafenib/trametinib, vemurafenib/cobimetinib and the most recently introduced encorafenib/binimetinib). As for checkpoint inhibitors, first line immunotherapy is represented by anti-PD1 blockers (nivolumab and pembrolizumab), whilst the anti-CTLA-4 ipilimumab can be used as second line immunotherapy. The decision-making factors that define the best treatment approach in stage IV patients with metastatic melanoma include the mutation pattern, performance status, high/low tumor load, brain metastases, progression pattern (low/fast), and availability of clinical trials. This review will analyze the current therapeutic tools adopted for the treatment of metastatic melanoma patients. It will then focus on the latest results obtained by novel treatments (checkpoint inhibitors and targeted therapies) which can be used in the clinical daily practice.

A Prospective Study of Intraarterial Infusion Chemotherapy in Advanced WT BRAF Melanoma Patients

BACKGROUND

Treatment strategies for advanced cutaneous melanoma (CM) patients, resistant or not treatable with novel target and immunotherapeutic drugs, remain a significant challenge, particularly for patients with unresectable stage IIIC/D disease localized to inferior limbs and pelvis, for whom specific outcomes are rarely considered.

MATERIALS AND METHODS

This is a prospective study of multidisciplinary treatments, including locoregional melphalan chemotherapy, in 62 BRAF wild-type CM patients with locoregional metastases in the inferior limbs and pelvis, including inguinal regions. Patients were either in progression following or ineligible for, or not treatable with novel immunotherapy. For exclusively inferior limb-localised disease, patients received locoregional melphalan chemotherapy performed by hyperthermic isolated limb perfusion (n = 19) or isolated limb infusion (n = 19), and for synchronous lesions localised to inferior limbs and pelvis, received hypoxic pelvic and limb perfusion (n = 24). Additional multidisciplinary therapy included local, locoregional and systemic treatments and the primary endpoint was tumour response.

RESULTS

The objective response rate following first cycle of locoregional chemotherapy was 37.1% at 3 mo and median progression-free survival was 4-mo, with 12.9% procedure-related complications, 30.6% low-grade haematological toxicity and 11.3% severe limb toxic tissue reactions. Multivariate logistic regression showed that the odds of response were significantly higher for patients ≤ 75 y of age and for patients with locoregional metastases exclusively located in the inferior limbs.

CONCLUSION

In this subgroup of CM patients with BRAF wild-type status, locoregional metastases localized to inferior limbs and pelvis, in progression following or ineligible for immunotherapy, melphalan locoregional chemotherapy demonstrated a safe and effective profile.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier NCT01920516; date of trial registration: August 6, 2013.

Case Report: Rechallenge With BRAF and MEK Inhibitors in Metastatic Melanoma: A Further Therapeutic Option in Salvage Setting?

Background

The combination of BRAF and MEK inhibitors represents the standard of care treatment for patients with metastatic BRAF-mutated melanoma, notwithstanding the high frequency of emergent resistance. Moreover, therapeutic options outside clinical trials are scarce when patients have progressed after both targeted therapy and therapy with immune checkpoint inhibitors. In this article, we report our experience with targeted therapy rechallenging with BRAF and MEK inhibitors in patients with metastatic BRAF-mutated melanoma after progression with kinase inhibitors and immunotherapy.

Methods

Four patients with metastatic BRAF-mutated melanoma were rechallenged with BRAF and MEK inhibitors after progression with targeted therapy and subsequent immunotherapy (checkpoint inhibitors).

Results

Two patients (one of them was heavily pretreated) had partial response over 36 months (with local treatment on oligoprogression disease) and 10 months, respectively. A third patient with multisite visceral disease and high serum levels of lactate dehydrogenase had a short-lived clinical benefit rapidly followed by massive progression of disease (early progressor). The fourth patient, currently on treatment with BRAF/MEK inhibitors, is showing a clinical benefit and radiological stable disease over 3 months of therapy. Adverse events were manageable, similar to those reported during the first targeted therapy; the treatment was better tolerated at rechallenge compared with the first treatment by two out of four patients.

Treatment Following Progression in Metastatic Melanoma: the State of the Art from Scientific Literature to Clinical Need

INTRODUCTION

In the last few years, the advent of targeted therapy and immunotherapy has improved the management and the prognosis of metastatic melanoma, but the spread of resistance mechanisms can lead to disease progression. The clinical management in this setting can be challenging because the oncologist has to decide what is the best treatment strategy among therapy beyond progression (TBP), therapy change, and the rechallenge approach. This review of the relevant scientific literature is intended to clarify which patients with progressing metastatic melanoma will benefit from continuation of ongoing therapy and which ones will not. The data are based on a total of about 4300 patients coming from the main retrospective studies in the chosen field. The article body is divided into four sections which analyze respectively the targeted therapy beyond progression, the immunotherapy beyond progression, the possible treatment sequences, and finally the rechallenge strategy.

RECENT FINDINGS

Despite the possible approaches of TBP or rechallenge, the patient may not have an optimal response and may need new therapy, which is currently missing. To broaden the pharmacological offer in the fight against melanoma, cancer research is studying new disease targets, like the NRAS, PI3K, and cKIT pathways or combination treatment of targeted therapy plus immunotherapy. Despite the limitations of this work, mainly due to the limited number of studies, their retrospective nature and the lack of comparative studies, the analysis performed allows us to draw some important conclusions: therapy beyond progression, both targeted therapy and immunotherapy, represents a valid treatment option with positive effects on disease control and survival outcomes for patients with low clinical risk, expressed as low disease burden, normal LDH levels, and good performance status; moreover, the prognosis and quality of life of these patients improve when TBP is associated with locoregional treatments. In patients with progressive metastatic melanoma and high clinical risk (high disease burden, high LDH levels, and poor performance status), it is recommended to change therapy, without ever forgetting the possibility of enrolling the patient in a clinical trial. Finally, an efficacious treatment alternative is the rechallenge strategy; this approach consists in a re-treatment with the same drug after a variable interval of discontinuation. Preliminary studies seem to have demonstrated that patients retreated with targeted therapy achieved a greater benefit if they had a low clinical risk and if the drug doublet (BRAF + MEK inhibitors) was used. On the side of immunotherapy, the rechallenge strategy produced a major benefit in patients who prior experienced a severe toxic episode.

Serum S100B and LDH at Baseline and During Therapy Predict the Outcome of Metastatic Melanoma Patients Treated with BRAF Inhibitors

BACKGROUND

Despite impressive response rates, most patients with advanced melanoma ultimately progress following therapy with B-Raf proto-oncogene (BRAF) inhibitors (BRAFi). Therefore, frequent radiologic assessments are necessary, and reliable serum biomarkers would be beneficial for disease monitoring.

OBJECTIVE

This study investigated the ability of lactate dehydrogenase (LDH) and S100 calcium-binding protein B (S100B) to detect response and disease progression during treatment with BRAFi.

PATIENTS AND METHODS

Baseline levels of LDH and S100B and repeated measurements during therapy were recorded retrospectively in 191 patients with metastatic melanoma. LDH and S100B levels were compared between distinct time points (baseline, first follow-up visit [FV], best objective response [BR], and progressive disease [PD]). The prognostic ability of the serum biomarkers in relation to disease-specific survival (DSS) was assessed with univariable and multivariable Cox regression analysis.

RESULTS

Elevated baseline LDH and S100B correlated with impaired DSS. In contrast with LDH (P = 0.12), S100B levels at FV correlated with response (P = 0.0030). Both markers significantly decreased during the first weeks of BRAFi treatment (LDH, P = 0.00034; S100B, P < 0.0001) and increased between BR and PD (LDH, P = 0.016; S100B, P < 0.0001). Patients with elevated S100B (P = 0.00062) but not with elevated LDH (P = 0.067) at the time point of radiologically confirmed PD showed significantly impaired DSS after PD. Interestingly, DSS after PD differed significantly according to S100B levels determined as early as 8 weeks (median) before PD (P = 0.0024).

CONCLUSIONS

LDH and S100B are suitable serum biomarkers during therapy with BRAFi. S100B shows stronger correlation with response and exhibits more accuracy in predicting PD. Close biomarker monitoring with S100B is recommended during treatment with BRAFi to detect PD early.

Dosing of BRAK and MEK Inhibitors in Melanoma: No Point in Taking a Break

Resistance to BRAF/MEK inhibitor treatment occurs in most patients with advanced BRAF^V600-mutant melanoma. Intermittent drug dosing had been proposed as a strategy to circumvent resistance. In a clinical trial published in Nature Medicine, continuous dosing of BRAF/MEK inhibitors produced superior progression-free survival compared to intermittent dosing in BRAF^V600-mutant melanoma patients.

ESMO consensus conference recommendations on the management of metastatic melanoma: under the auspices of the ESMO Guidelines Committee

The European Society for Medical Oncology (ESMO) held a consensus conference on melanoma on 5-7 September 2019 in Amsterdam, The Netherlands. The conference included a multidisciplinary panel of 32 leading experts in the management of melanoma. The aim of the conference was to develop recommendations on topics that are not covered in detail in the current ESMO Clinical Practice Guideline and where available evidence is either limited or conflicting. The main topics identified for discussion were (i) the management of locoregional disease; (ii) targeted versus immunotherapies in the adjuvant setting; (iii) targeted versus immunotherapies for the first-line treatment of metastatic melanoma; (iv) when to stop immunotherapy or targeted therapy in the metastatic setting; and (v) systemic versus local treatment for brain metastases. The expert panel was divided into five working groups to each address questions relating to one of the five topics outlined above. Relevant scientific literature was reviewed in advance. Recommendations were developed by the working groups and then presented to the entire panel for further discussion and amendment before voting. This manuscript presents the results relating to the management of metastatic melanoma, including findings from the expert panel discussions, consensus recommendations and a summary of evidence supporting each recommendation. All participants approved the final manuscript.

Impact of initial treatment and prognostic factors on postprogression survival in BRAF-mutated metastatic melanoma treated with dacarbazine or vemurafenib ± cobimetinib: a pooled analysis of four clinical trials

BACKGROUND

We sought to identify patient subgroups with distinct postprogression overall survival (ppOS) outcomes and investigate the impact of original treatment assignment and initial postprogression treatment (ppRx) on ppOS.

METHODS

Recursive partitioning analysis (RPA) was performed to model relationships between prespecified covariates and ppOS in patients with BRAF^V600-mutated metastatic melanoma who had experienced progressive disease (PD) following treatment with cobimetinib plus vemurafenib, vemurafenib monotherapy, or dacarbazine in the BRIM-2, BRIM-3, BRIM-7, and coBRIM studies. Prognostic subgroups identified by RPA were then applied to pooled treatment cohorts. The primary endpoint was ppOS, defined as time from first PD to death from any cause.

RESULTS

RPA identified baseline lactate dehydrogenase (LDH), baseline disease stage, Eastern Cooperative Oncology Group performance status at PD, and ppRx as significant prognostic factors for ppOS. Median ppOS was longest in patients with normal baseline LDH, stage M1c disease at baseline, and ppRx with immunotherapy or targeted therapy (12.2 months; 95% CI 10.3-16.1) and shortest in those with elevated baseline LDH > 2 × upper limit of normal (2.3 months; 95% CI 1.8-2.7). Original treatment assignment did not impact ppOS. Across treatment cohorts, patients treated with immunotherapy or targeted therapy after PD had better ppOS than those given other treatments.

CONCLUSION

A combination of factors at baseline (LDH, disease stage) and PD (performance status, ppRx) impact ppOS outcomes. ppRx with immunotherapy or targeted therapy is an independent prognostic factor for improved overall survival following progression regardless of original treatment. Trial registration The trials included in this analysis are registered with ClinicalTrials.gov: NCT00949702 (BRIM-2), NCT01006980 (BRIM-3), NCT01271803 (BRIM-7), and NCT01689519 (coBRIM).

Current State of Target Treatment in BRAF Mutated Melanoma

Incidence of melanoma has been constantly growing during the last decades. Although most of the new diagnoses are represented by thin melanomas, the number of melanoma-related deaths in 2018 was 60,712 worldwide (Global Cancer Observatory, 2019). Until 2011, no systemic therapy showed to improve survival in patients with advanced or metastatic melanoma. At that time, standard of care was chemotherapy, with very limited results. The identification of BRAF V600 mutation, and the subsequent introduction of BRAF targeting drugs, radically changed the clinical practice and dramatically improved outcomes. In this review, we will retrace the development of molecular-target drugs and the current therapeutic scenario for patients with BRAF mutated melanoma, from the introduction of BRAF inhibitors as single agents to modern clinical practice. We will also discuss the resistance mechanisms identified so far, and the future therapeutic perspectives in BRAF mutated melanoma.

Circulating tumour cell liquid biopsy in selecting therapy for recurrent cutaneous melanoma with locoregional pelvic metastases: a pilot study

OBJECTIVES

Circulating tumour cells (CTCs) from liquid biopsies provide an exceptional opportunity to obtain real-time tumour information and are under current investigation in several cancers, including cutaneous melanoma, but face significant drawbacks in terms of non-standardised methodology, low viable cell numbers and accuracy of CTC identification. In this pilot study, we report that chemosensitivity assays using liquid biopsy-derived metastatic melanoma (MM) CTCs, from 7 patients with stage IIIC, BRAF wild-type metastatic melanomas, localized exclusively to the pelvic region, un-eligible for immunotherapy and treated with melphalan hypoxic pelvic perfusion (HPP), is both feasible and useful in predicting response to therapy. Viable MM CTCs (> 5 cells/ml for all 7 blood samples), enriched by transient culture, were characterised in flow cytometry-based Annexin V-PE assays for chemosensitivity to several drugs.

RESULTS

Using melphalan as a standard, chemosensitivity cut-off values of > 60% cell death, were predictive of patient RECIST 1.1 response to melphalan HPP therapy, associated with calculated 100% sensitivity, 66.67% specificity, 33.33% positive predictive, 100% negative predictive, and 71.43% accuracy values. We propose that the methodology in this study is both feasible and has potential value in predicting response to therapy, setting the stage for a larger study. Trial registration Clinical Trials.gov Identifier NCT01920516; date of trial registration: August 6, 2013.

The Management of Oligoprogression in the Landscape of New Therapies for Metastatic Melanoma

Background: A limited degree of progression after a response to treatment is labelled as oligoprogression and is a hot topic of metastatic melanoma (MM) management. Rogue progressive metastases could benefit from local treatment, which could allow the continuation of ongoing systemic therapy, also known as treatment beyond progression (TBP). Methods: We retrospectively reviewed 214 selected MM patients who developed oligoprogression during treatment with v-Raf murine sarcoma viral oncogene homolog B (BRAF)/mitogen-activated-extracellular signal-regulated kinase (MEK) or programmed cell death protein 1 (PD-1) inhibitors and received a local treatment continuing TBP. We performed univariate and multivariable analyses to assess the association between therapy outcomes and a series of clinical and biological features. Results: We identified 27 (10%) oligoprogressed patients treated locally with surgery (14), radiosurgery (11), and electrochemotherapy (2). TBP included PD-1 inhibitors (13) and BRAF/MEK inhibitors (14). The median progression-free survival post oligoprogression (PFSPO) was 14 months (5-19 95% confidence interval (C.I.)). In the univariate analysis, a significantly longer PFSPO was associated with complete response (CR), Eastern Cooperative Oncology Group (ECOG) performance status (PS) of 0, neutrophils/lymphocytes ratio (N/L) <2, and progression-free survival (PFS) at oligoprogression >11 months. Nevertheless, in the multivariable analysis, only CR and N/L <2 were found to be associated with longer PFSPO. Conclusions: In selected patients, local treatments contribute to controlling oligoprogression for a long time, allowing the continuation of systemic treatment and prolongation of overall survival (OS). Increasing biological and clinical knowledge is improving the accuracy in identifying patients to apply for local ablative therapies.

A Fatty Acid Oxidation-dependent Metabolic Shift Regulates the Adaptation of BRAF-mutated Melanoma to MAPK Inhibitors

PURPOSE

Treatment of BRAF^V600E -mutant melanomas with MAPK inhibitors (MAPKi) results in significant tumor regression, but acquired resistance is pervasive. To understand nonmutational mechanisms underlying the adaptation to MAPKi and to identify novel vulnerabilities of melanomas treated with MAPKi, we focused on the initial response phase during treatment with MAPKi.

EXPERIMENTAL DESIGN

By screening proteins expressed on the cell surface of melanoma cells, we identified the fatty acid transporter CD36 as the most consistently upregulated protein upon short-term treatment with MAPKi. We further investigated the effects of MAPKi on fatty acid metabolism using in vitro and in vivo models and analyzing patients' pre- and on-treatment tumor specimens.

RESULTS

Melanoma cells treated with MAPKi displayed increased levels of CD36 and of PPARα-mediated and carnitine palmitoyltransferase 1A (CPT1A)-dependent fatty acid oxidation (FAO). While CD36 is a useful marker of melanoma cells during adaptation and drug-tolerant phases, the upregulation of CD36 is not functionally involved in FAO changes that characterize MAPKi-treated cells. Increased FAO is required for BRAF^V600E -mutant melanoma cells to survive under the MAPKi-induced metabolic stress prior to acquiring drug resistance. The upfront and concomitant inhibition of FAO, glycolysis, and MAPK synergistically inhibits tumor cell growth in vitro and in vivo.

CONCLUSIONS

Thus, we identified a clinically relevant therapeutic approach that has the potential to improve initial responses and to delay acquired drug resistance of BRAF^V600E -mutant melanoma.

A Brief Overview of the Antitumoral Actions of Leelamine

For the last couple of decades, natural products, either applied singly or in conjunction with other cancer therapies including chemotherapy and radiotherapy, have allowed us to combat different types of human cancers through the inhibition of their initiation and progression. The principal sources of these useful compounds are isolated from plants that were described in traditional medicines for their curative potential. Leelamine, derived from the bark of pine trees, was previously reported as having a weak agonistic effect on cannabinoid receptors and limited inhibitory effects on pyruvate dehydrogenase kinases (PDKs). It has been reported to possess a strong lysosomotropic property; this feature enables its assembly inside the acidic compartments within a cell, such as lysosomes, which may eventually hinder endocytosis. In this review, we briefly highlight the varied antineoplastic actions of leelamine that have found implications in pharmacological research, and the numerous intracellular targets affected by this agent that can effectively negate the oncogenic process.

Efficacy of PD-1-based immunotherapy after radiologic progression on targeted therapy in stage IV melanoma

OBJECTIVES

Targeted therapy (TT) is an effective treatment for advanced BRAFV600-mutated melanoma, but most patients eventually acquire resistance and progress. Here, we evaluated the outcome of second-line immune checkpoint blockade (ICB) after progression on dual BRAF and MEK inhibition.

METHODS

Patients with metastatic melanoma progressing on combined BRAF + MEK inhibition and receiving second-line ICB between 2015 and 2019 in 9 tertiary referral centres were enrolled. Demographic and clinical data and blood counts of all patients were collected retrospectively.

RESULTS

We identified 99 patients with stage IV melanoma receiving ICB (nivolumab, pembrolizumab [n = 39] or ipilimumab plus nivolumab [n = 60]) after progression on combined TT. The median progression-free survival was similar in the PD-1 and ipilimumab plus nivolumab group (2.6 months [95% confidence interval {CI}, 2.0-3.1] vs. 2.0 [95% CI, 1.4-2.6], p = 0.15). The objective response rate was 18.0% in the PD-1 and 15.0% in the ipilimumab plus nivolumab group (p = 0.70). The disease control rate was 25.7% for monotherapy and 18.3% for combined ICB (p = 0.39). The median overall survival was 8.4 months (95% CI, 5.1-11.7) for patients receiving PD-1 monotherapy and 7.2 months (95% CI, 5.2-9.1) for patients receiving ipilimumab plus nivolumab (p = 0.86). The latter was associated with a higher rate of treatment-related adverse events (AEs). No significant association of laboratory values or clinicopathological characteristics with response to second-line ICB was observed.

CONCLUSIONS

PD-1 monotherapy and combined ipilimumab plus nivolumab show similar activity and outcome in patients with melanoma resistant to BRAF + MEK inhibition. However, combined ipilimumab plus nivolumab was associated with a higher rate of treatment-related AEs compared with monotherapy.

Identifying the structure-activity relationship of leelamine necessary for inhibiting intracellular cholesterol transport

Leelamine is an anticancer chemotherapeutic agent inhibiting intracellular cholesterol transport. Cell death mediated by leelamine occurs due to the lysosomotropic property of the compound, its accumulation in the lysosome, and inhibition of cholesterol transport leading to lack of availability for key processes required for functioning of cancer cells. The present study dissects the structure-activity-relationship of leelamine using synthesized derivatives of leelamine and abietic acid, a structurally similar compound, to identify the moiety responsible for anti-cancer activity. Similar to leelamine, all active derivatives had an amino group or a similar moiety that confers a lysosomotropic property to the compound enabling its accumulation in the lysosome. Active derivatives inhibited intracellular cholesterol transport and hindered xenografted melanoma tumor development without obvious systemic toxicity. In silico studies suggested that active derivatives accumulating in lysosomes bound to NPC1, a protein responsible for cholesterol export from the lysosome, to inhibit its activity that then caused accumulation, and lack of cholesterol availability for other key cellular activities. Thus, active derivatives of leelamine or abietic acid maintained lysosomotropic properties, bound to NPC1, and disrupted cellular cholesterol transport as well as availability to retard tumor development.

Improved survival of patients with melanoma brain metastases in the era of targeted BRAF and immune checkpoint therapies

BACKGROUND

The development of brain metastases is common for systemic treatment failure in patients with melanoma and has been associated with a poor prognosis. Recent advances with BRAF and immune checkpoint therapies have led to improved patient survival. Herein, the authors evaluated the risk of de novo brain metastases and survival among patients with melanoma brain metastases (MBM) since the introduction of more effective therapies.

METHODS

Patients with unresectable AJCC stage III/IV melanoma who received first-line systemic therapy at Moffitt Cancer Center between 2000 and 2012 were identified. Data were collected regarding patient characteristics, stage of disease, systemic therapies, MBM status/management, and overall survival (OS). The risk of de novo MBM was calculated using a generalized estimating equation model and survival comparisons were performed using Kaplan-Meier and Cox proportional analyses.

RESULTS

A total of 610 patients were included, 243 of whom were diagnosed with MBM (40%). Patients with MBM were younger, with a lower frequency of regional metastasis. No significant differences were noted with regard to sex, BRAF status, or therapeutic class. The risk of de novo MBM was found to be similar among patients treated with chemotherapy, biochemotherapy, BRAF-targeted therapy, ipilimumab, and anti-programmed cell death protein 1/programmed death-ligand 1 regimens. The median OS of patients with MBM was significantly shorter when determined from the time of first regional/distant metastasis but not when determined from the time of first systemic therapy. The median OS from the time of MBM diagnosis was 7.5 months, 8.5 months, and 22.7 months, respectively, for patients diagnosed from 2000 to 2008, 2009 to 2010, and 2011 to the time of last follow-up (P = .002).

CONCLUSIONS

Brain metastases remain a common source of systemic treatment failure. The OS for patients with MBM has improved significantly. Further research into MBM prevention is needed. Cancer 2018;124:297-305. © 2017 American Cancer Society.

Progression patterns under BRAF inhibitor treatment and treatment beyond progression in patients with metastatic melanoma

Despite markedly improved treatment options for metastatic melanoma, resistance to targeted therapies such as BRAF inhibitors (BRAFi) or BRAFi plus MEK inhibitors (MEKi) remains a major problem. Our aim was to characterize progression on BRAFi therapy and outcome of subsequent treatment. One hundred and eighty patients with BRAF-mutant metastatic melanoma who had progressed on treatment with single-agent BRAFi from February 2010 to April 2015 were included in a retrospective data analysis focused on patterns of progression, treatment beyond progression (TBP) and subsequent treatments after BRAFi therapy. Analysis revealed that 51.1% of patients progressed with both new and existing metastases opposed to progression of only preexisting (28.3%) or only new (20.6%) metastases. Exclusive extracranial progression occurred in 50.6% of patients compared to both extra- and intracranial (29.4%) or sole cerebral progression (20%). Multivariable analyses demonstrated that single site progression and primary response to BRAFi were associated with improved progression-free survival. Progression with exclusively new or only existing metastases and a baseline Eastern Cooperative Oncology Group (ECOG) of 0 were associated with prolonged overall survival (OS). TBP had no significant impact on OS. Other subsequent treatments showed low efficacy with the exception of anti-PD-1 antibodies. In conclusion we identified specific patterns of progression which significantly correlate with further prognosis after progression on BRAFi treatment. In contrast to previously published data, we could not demonstrate a significant survival benefit for BRAFi TBP. Subsequent therapies had strikingly low efficacy except for PD-1 inhibitors.

HDAC inhibitors restore BRAF-inhibitor sensitivity by altering PI3K and survival signalling in a subset of melanoma

Mutations in BRAF activate oncogenic MAPK signalling in almost half of cutaneous melanomas. Inhibitors of BRAF (BRAFi) and its target MEK are widely used to treat melanoma patients with BRAF mutations but unfortunately acquired resistance occurs in the majority of patients. Resistance results from mutations or non-genomic changes that either reactivate MAPK signalling or activate other pathways that provide alternate survival and growth signalling. Here, we show the histone deacetylase inhibitor (HDACi) panobinostat overcomes BRAFi resistance in melanoma, but this is dependent on the resistant cells showing a partial response to BRAFi treatment. Using patient- and in vivo-derived melanoma cell lines with acquired BRAFi resistance, we show that combined treatment with the BRAFi encorafenib and HDACi panobinostat in 2D and 3D culture systems synergistically induced caspase-dependent apoptotic cell death. Key changes induced by HDAC inhibition included decreased PI3K pathway activity associated with a reduction in the protein level of a number of receptor tyrosine kinases, and cell line dependent upregulation of pro-apoptotic BIM or NOXA together with reduced expression of anti-apoptotic proteins. Independent of these changes, panobinostat reduced c-Myc and pre-treatment of cells with siRNA against c-Myc reduced BRAFi/HDACi drug-induced cell death. These results suggest that a combination of HDAC and MAPK inhibitors may play a role in treatment of melanoma where the resistance mechanisms are due to activation of MAPK-independent pathways.

Targeting the PTTG1 oncogene impairs proliferation and invasiveness of melanoma cells sensitive or with acquired resistance to the BRAF inhibitor dabrafenib

The pituitary tumor transforming gene 1 (PTTG1) is implicated in tumor growth, metastasis and drug resistance. Here, we investigated the involvement of PTTG1 in melanoma cell proliferation, invasiveness and response to the BRAF inhibitor (BRAFi) dabrafenib. We also preliminary assessed the potential value of circulating PTTG1 protein to monitor melanoma patient response to BRAFi or to dabrafenib plus trametinib. Dabrafenib-resistant cell lines (A375R and SK-Mel28R) were more invasive than their drug-sensitive counterparts (A375 and SK-Mel28), but expressed comparable PTTG1 levels. Dabrafenib abrogated PTTG1 expression and impaired invasion of the extracellular matrix (ECM) in A375 and SK-Mel28 cells. In contrast, it affected neither PTTG1 expression in A375R and SK-Mel28R cells, nor ECM invasion in the latter cells, while further stimulated A375R cell invasiveness. Assessment of proliferation and ECM invasion in control and PTTG1-silenced A375 and SK-Mel28 cells, exposed or not to dabrafenib, demonstrated that the inhibitory effects of this drug were, at least in part, dependent on its ability to down-regulate PTTG1 expression. PTTG1-silencing also impaired proliferation and invasiveness of A375R and SK-Mel28R cells, and counteracted dabrafenib-induced stimulation of ECM invasion in A375R cells. Further experiments performed in A375R cells indicated that PTTG1-silencing impaired cell invasiveness through inhibition of MMP-9 and that PTTG1 expression and ECM invasion could be also reduced by the CDK4/6 inhibitor LEE011. PTTG1 targeting might, therefore, represent a useful strategy to impair proliferation and metastasis of melanomas resistant to BRAFi. Circulating PTTG1 also appeared to deserve further investigation as biomarker to monitor patient response to targeted therapy.

Does Locoregional Chemotherapy Still Matter in the Treatment of Advanced Pelvic Melanoma?

Pelvic Melanoma relapse occurs in 15% of patients with loco regional metastases, and 25% of cases do not respond to new target-therapy and/or immunotherapy. Melphalan hypoxic pelvic perfusion may, therefore, be an option for these non-responsive patients. Overall median survival time (MST), stratified for variables, including BRAF V600E mutation and eligibility for treatments with new immunotherapy drugs, was retrospectively assessed in 41 patients with pelvic melanoma loco regional metastases. They had received a total of 175 treatments with Melphalan hypoxic perfusion and cytoreductive excision. Among the 41 patients, 22 (53.7%) patients exhibited a wild-type BRAF genotype, 11 of which were not eligible for immunotherapy. The first treatment resulted in a 97.5% response-rate in the full cohort and a 100% response-rate in the 22 wild-type BRAF patients. MST was 18 months in the full sample, 20 months for the 22 wild-type BRAF patients and 21 months for the 11 wild-type BRAF patients not eligible for immunotherapy. Melphalan hypoxic perfusion is a potentially effective treatment for patients with pelvic melanoma loco regional metastases that requires confirmation in a larger multicenter study.

Challenges in Conducting Clinical Research on Patients With Advanced Melanoma

Unprecedented advances in the treatment of melanoma and the large number of investigational therapies entering clinical studies not only represent outstanding achievements, but also create major challenges for clinical research in melanoma. The challenges for accrual and for developing important new data in trials include the relatively low incidence of melanoma compared with other diseases, a shrinking pool of patients for trials because of the high efficacy of standard of care therapy, requirements for larger studies and longer duration of follow-up to detect signals of activity or establish efficacy, and suboptimal predictive biomarkers for the vast number of new combinations and new agents. The cost of new treatments remains a major concern, particularly because current standard of care involves doublets of targeted therapy or immune therapy, and clinically meaningful further increases in efficacy may require development of triplets or larger multidrug combinations. Toxicities of the current doublets, particularly for immune therapy, may limit development of some multidrug regimens or may require novel solutions such as sequencing or alternating schedules. The activity of first-line therapies may push development of new drugs or combinations into the second-line setting or into subgroups with suboptimal response to the first-line doublets as identified by predictive clinical variables or tissue biomarkers.

Combination of dabrafenib plus trametinib for BRAF and MEK inhibitor pretreated patients with advanced BRAFV600-mutant melanoma: an open-label, single arm, dual-centre, phase 2 clinical trial

BACKGROUND

Patients with BRAF^V600-mutant melanoma benefit from treatment with the combination of BRAF and MEK inhibitors, but resistance and disease progression develops in most patients. Preclinical studies and case studies have indicated that acquired resistance to BRAF inhibition can be reversible. We aimed to assess the anti-tumour activity of rechallenge with BRAF plus MEK inhibition in a prospective clinical trial.

METHODS

In this open-label, single arm, dual-centre, phase 2 academic study in Belgium, patients aged 18 years or older with BRAF^V600-mutant melanoma who had previously progressed on BRAF inhibitors (with or without MEK inhibitors) and were off-treatment for at least 12 weeks, were treated with dabrafenib 150 mg orally twice per day plus trametinib 2 mg orally once per day. The primary endpoint was the proportion of patients with investigator-assessed overall response at any time (defined as complete response or partial response according to Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1 confirmed on two occasions, at least 28 days after the first response was recorded). Analyses were done in the intention-to-treat population. The study is ongoing but no longer recruiting patients. This trial is registered with ClinicalTrials.gov, number NCT02296996.

FINDINGS

Between April 5, 2014, and Feb 2, 2016, 25 patients were enrolled and initiated treatment in our study. A partial response was documented in eight (32%) of 25 patients (95% CI 15-54; six patients had progressed on previous treatment with dabrafenib plus trametinib and two patients had progressed on previous BRAF inhibitor monotherapy). Stable disease was noted in ten patients (40%; 95% CI 21-61). Rechallenge with dabrafenib plus trametinib was well tolerated. There were no unexpected or grade 4 or 5 treatment-related adverse events. Grade 3 adverse events occurred in two patients (8%; panniculitis [n=1] and pyrexia [n=1]). Serious adverse events which occurred on study were one patient with an Addison crisis triggered by grade 2 pyrexia symptoms that resolved after discontinuation of dabrafenib and trametinib. No patients died as a result of study treatment.

INTERPRETATION

Rechallenge with dabrafenib plus trametinib showed anti-tumour activity in patients who had previously progressed on BRAF inhibitors and as such, rechallenge represents a potential new treatment option for these patients.

FUNDING

Vlaamse Liga Tegen Kanker, Novartis.

Dependence On Glycolysis Sensitizes BRAF-mutated Melanomas For Increased Response To Targeted BRAF Inhibition

Dysregulated metabolism can broadly affect therapy resistance by influencing compensatory signaling and expanding proliferation. Given many BRAF-mutated melanoma patients experience disease progression with targeted BRAF inhibitors, we hypothesized therapeutic response is related to tumor metabolic phenotype, and that altering tumor metabolism could change therapeutic outcome. We demonstrated the proliferative kinetics of BRAF-mutated melanoma cells treated with the BRAF inhibitor PLX4720 fall along a spectrum of sensitivity, providing a model system to study the interplay of metabolism and drug sensitivity. We discovered an inverse relationship between glucose availability and sensitivity to BRAF inhibition through characterization of metabolic phenotypes using nearly a dozen metabolic parameters in Principle Component Analysis. Subsequently, we generated rho0 variants that lacked functional mitochondrial respiration and increased glycolytic metabolism. The rho0 cell lines exhibited increased sensitivity to PLX4720 compared to the respiration-competent parental lines. Finally, we utilized the FDA-approved antiretroviral drug zalcitabine to suppress mitochondrial respiration and to force glycolysis in our cell line panel, resulting in increased PLX4720 sensitivity via shifts in EC50 and Hill slope metrics. Our data suggest that forcing tumor glycolysis in melanoma using zalcitabine or other similar approaches may be an adjunct to increase the efficacy of targeted BRAF therapy.

Signaling and Immune Regulation in Melanoma Development and Responses to Therapy

Melanoma is a complex and genomically diverse malignancy, and new genes and signaling pathways involved in pathogenesis continue to be discovered. Mechanistic insights into gene and immune regulation in melanoma have led to the development of numerous successful and innovative pharmacologic agents over recent years. Multiple targeted therapies and immunotherapies have already entered the clinic, becoming new standards of care and transforming the prognosis for many patients with malignant melanoma. In this review, we provide an overview of the current understanding of signaling and immune regulation in melanoma and implications for responses to treatment, organized in the framework of hallmark characteristics in cancer.

Factors predictive of response, disease progression, and overall survival after dabrafenib and trametinib combination treatment: a pooled analysis of individual patient data from randomised trials

BACKGROUND

Dabrafenib plus trametinib treatment provides significant benefits over BRAF-inhibitor monotherapy in patients with BRAF^V600E-mutant or BRAF^V600K-mutant advanced melanoma; however, in many patients the disease progresses, leading to death. With many treatment options available, understanding clinical factors that predict long-term response and survival for treatments is important for optimisation of patient management. We aimed to identify clinical factors associated with long-term response and survival using pooled data from randomised trials of dabrafenib plus trametinib in patients with metastatic BRAF-mutant melanoma.

METHODS

We did a retrospective individual data analysis based on all published randomised trials that included treatment-naive patients with BRAF^V600E-mutant or BRAF^V600K-mutant metastatic melanoma who received the approved dose of dabrafenib 150 mg twice daily plus trametinib 2 mg once daily. Data were pooled from patients in the BRF113220 (part C; March 26, 2010, to Jan 15, 2015), COMBI-d (May 4, 2012, to Jan 12, 2015), and COMBI-v (June 4, 2012, to March 13, 2015) randomised trials. Patients with untreated brain metastases were not permitted to enrol in these trials. Baseline factors, identified a priori based on known melanoma clinical or prognostic characteristics, were analysed for association with progression-free survival and overall survival using univariate and multivariate analyses and assessed for hierarchical effect on outcomes using regression tree analyses. We also analysed factors identified after baseline, on treatment, and at progression, for associations with survival after progression. The trials included in this analysis are registered with ClinicalTrials.gov: BRF113220, number NCT01072175; COMBI-d, number NCT01584648; COMBI-v, number NCT01597908.

FINDINGS

617 patients were included in this analysis with a median follow-up of 20·0 months (range 0-48·0, IQR 10·1-24·8); 396 patients had progression events (ie, disease progression or death) and 290 patients had died. Median progression-free survival (11·1 months [95% CI 9·7-12·9]), median overall survival (25·6 months [23·1-34·3]), 1-year progression-free survival (48% [44-52]) and overall survival (74% [71-78]), and 2-year progression-free survival (30% [26-34]) and overall survival (53% [49-57]) were consistent with those in the individual trials. Patients with normal lactate dehydrogenase (LDH) concentration and fewer than three organ sites containing metastases (n=237) had the longest 1-year progression-free survival (68% [95% CI 62-74]) and overall survival (90% [87-94]) and 2-year progression-free survival (46% [40-54]) and overall survival (75% [70-81]), whereas patients with LDH concentration at least two times the upper limit of normal (n=70) had the shortest 1-year progression-free survival (8% [3-19]) and overall survival (40% [29-55]) and 2-year progression-free survival (2% [0-13]) and overall survival (7% [3-19]). Of patients with disease progression (n=379), survival after progression was longest in those with progression in baseline or new non-CNS lesions (n=205; median 10·0 months [95% CI 7·9-12·0]) and shortest in those with new CNS lesions or concurrent progression in baseline and new lesions (n=171; median 4·0 months [3·5-4·9]).

INTERPRETATION

Several patient and clinical characteristics at and after baseline are associated with outcomes with dabrafenib plus trametinib, and durable benefit is possible with targeted treatment in defined patient subsets.

FUNDING

Novartis.

Synergistic inhibitory effects of Celecoxib and Plumbagin on melanoma tumor growth

Melanoma is a highly drug resistant cancer. To circumvent this problem, a class of synergistically acting drug combinations, which inhibit multiple key pathways in melanoma cells, could be used as one approach for long-term treatment of this deadly disease. A screen has been undertaken on cell lines to identify those that could be combined to synergistically kill melanoma cells. Plumbagin and Celecoxib are two agents that were identified to synergistically kill melanoma cells by inhibiting the COX-2 and STAT3 pathways, which are constitutively activated in up to 70% of melanomas. The combination of these two drugs was more effective at killing melanoma cells than normal cells and decreased cellular proliferation as well as induced apoptosis of cultured cells. The drug combination inhibited development of xenograft melanoma tumors by up to 63% without affecting animal weight or blood biomarkers of organ function, suggesting negligible toxicity. Mechanistically, combination of Celecoxib and Plumbagin decreased melanoma cell proliferation and retarded vascular development of tumors mediated by inhibition of COX-2 and STAT3 leading to decreased levels of key cyclins key on which melanoma cell were dependent for survival.

Treatment of malignant melanoma with nivolumab and vemurafenib combined with hypofractionated radiation therapy

Management of metastatic malignant melanoma is challenging. Although several new systemic therapies for metastatic malignant melanoma have recently been developed, some patients still also require radiation therapy (RT) for palliative care. However, the safety and efficacy of combining use of novel drugs with RT remain unclear. Here, we report treating a patient with rapidly growing malignant melanoma with a programmed cell death protein 1 (PD-1) inhibitor and a BRAF inhibitor together with 60 Gy of hypofractionated RT without severe adverse effects. The tumor within the radiation field exhibited a more marked response than that outside it. A combination of RT with an anti-PD-1 antibody or a BRAF inhibitor may, therefore, be a useful and tolerable approach to treating metastatic BRAF-mutant melanoma.

Combined vemurafenib and fotemustine in patients with BRAF V600 melanoma progressing on vemurafenib

Background

BRAF inhibitor vemurafenib achieves high response rate and an improvement in survival in patients with BRAF-mutated metastatic melanoma. However, median progression-free survival is only 6.9 months in the phase 3 study. Retrospective analyses suggest that treatment with BRAF inhibitors beyond initial progression might be associated with improved overall survival. We aimed to prospectively investigate the activity of prolonged treatment with vemurafenib and the addition of fotemustine in patients with systemic progression on prior single-agent BRAF inhibitor.

Patients and Methods

In this two-centres, single-arm Phase 2 trial, we enrolled patients with systemic progressive disease during single-agent vemurafenib treatment. Participants received vemurafenib 960 mg twice daily or dose administered at time of disease progression with vemurafenib previous treatment and fotemustine 100 mg/m2 intravenously every three weeks. The primary endpoint was PFS.

Results

Thirty-one patients were enrolled in the study; 16 patients had brain metastases at baseline. Median PFS was 3.9 months and 19 patients (61.3%) achieved disease control (1 CR, 4 PR, 14 SD). For patients achieving disease control, median duration of treatment was 6 months. Median OS was 5.8 months from enrolment and 15.4 months from start of previous vemurafenib. Five patients (16.1%) had a G3-4 AE, the most common being thrombocytopenia, which occurred in 3 patients.

This trial is registered with ClinicalTrials.gov number NCT01983124.

Conclusion

The combination of vemurafenib plus fotemustine has clinical activity and an acceptable safety profile in BRAF-refractory patients.

Targeting the PI3K/AKT/mTOR pathway overcomes the stimulating effect of dabrafenib on the invasive behavior of melanoma cells with acquired resistance to the BRAF inhibitor

BRAF inhibitors (BRAFi) have proven clinical benefits in patients with BRAF-mutant melanoma. However, acquired resistance eventually arises. The effects of BRAFi on melanoma cell proliferation and survival have been extensively studied, and several mechanisms involved in acquired resistance to the growth suppressive activity of these drugs have been identified. Much less is known about the impact of BRAFi, and in particular of dabrafenib, on the invasive potential of melanoma cells. In the present study, the BRAF-mutant human melanoma cell line A375 and its dabrafenib-resistant subline A375R were analyzed for invasive capacity, expression of vascular endothelial growth factor receptor (VEGFR)-2, and secretion of VEGF-A and matrix metalloproteinase (MMP)-9, under basal conditions or in response to dabrafenib. The consequences of inhibiting the PI3K/AKT/mTOR pathway on A375R cell responses to dabrafenib were also evaluated. We found that A375R cells were more invasive and secreted higher levels of VEGF-A and MMP-9 as compared with A375 cells. Dabrafenib reduced invasiveness, VEGFR-2 expression and VEGF-A secretion in A375 cells, whereas it increased invasiveness, VEGF-A and MMP-9 release in A375R cells. In these latter cells, the stimulating effects of dabrafenib on the invasive capacity were markedly impaired by the anti-VEGF‑A antibody bevacizumab, or by AKT1 silencing. A375R cells were not cross-resistant to the PI3K/mTOR inhibitor GSK2126458A. Moreover, this inhibitor given in combination with dabrafenib efficiently counteracted the stimulating effects of the BRAFi on invasiveness and VEGF-A and MMP-9 secretion. Our data demonstrate that melanoma cells with acquired resistance to dabrafenib possess a more invasive phenotype which is further stimulated by exposure to the drug. Substantial evidence indicates that continuing BRAFi therapy beyond progression produces a clinical benefit. Our results suggest that after the development of resistance, a regimen combining BRAFi with bevacizumab or with inhibitors of the PI3K/AKT/mTOR pathway might be more effective than BRAFi monotherapy.

The evolution of combined molecular targeted therapies to advance the therapeutic efficacy in melanoma: a highlight of vemurafenib and cobimetinib

Metastatic melanoma is an aggressive, rapidly progressive disease which historically had very few effective treatment options. However, since 2011, the therapeutic landscape of melanoma has undergone a dramatic transformation with two distinct approaches and has catalyzed the successful advancement in the clinical field of immuno-oncology. In addition, the recognition of a key oncogenic driver mutation in melanoma, BRAF, stimulated the development of multiple potent kinase inhibitors which has also influenced the expansion and use of targeted agents in the practice of oncology. Vemurafenib, the initial BRAF inhibitor approved for the treatment of melanoma, was the first agent to demonstrate rapid clinical responses and significantly improved survival which was a clinical breakthrough in the treatment of melanoma. Although exciting and practice changing, the unparalleled responses with vemurafenib are usually not sustained. Further investigations delineated several mechanisms of acquired resistance which are most often mediated by the upregulation of the MAPK pathway. MEK inhibitors, another class of small-molecule inhibitors, were developed as an alternative agent to suppress the MAPK pathway downstream, independent from BRAF activation. Multiple studies have demonstrated the improvement in antitumor activity when MEK inhibitors are used in combination with BRAF inhibitors in the treatment of metastatic melanoma. This is a review of the investigations that led to the US Food and Drug Administration approval in 2015 of the combination of vemurafenib and cobimetinib, adding to the quickly growing armament for the treatment of advanced or metastatic melanoma with a BRAF V600 mutation.

Dabrafenib in metastatic melanoma: a monocentric 'real life' experience

Dabrafenib is a potent BRAF-kinase inhibitor. Its activity was evaluated on 40 consecutive metastatic melanoma patients (pts) harboring the V600BRAF mutations. Dabrafenib was administered orally at the dosage of 150 mg b.i.d. daily. ORR was 82%, with 7% CR, 62% PR, 13% SD and 18% PD. The median PFS and OS were seven and 17 months, respectively (median follow-up: 8.5 months). Increased risk of progression was found in pts with elevated LDH, ECOG PS >1 and more than two metastatic sites. Grade 3–4 adverse events were recorded in 4 pts. In this retrospective analysis, Dabrafenib confirmed its role as the standard clinical option in metastatic melanoma pts.

Biology and treatment of BRAF mutant metastatic melanoma

BRAF inhibitors were among the first systemic therapies to show clinical benefit in metastatic melanoma. Here, we review the spectrum of BRAF mutations in melanoma, their role in oncogenesis, clinicopathological associations and response to treatment. The differing biology and clinical features of V600E- and V600K-mutated melanoma are outlined. The molecular changes associated with BRAF fusion genes and their response to targeted therapies, as well as the role of immunotherapy in treatment sequencing with targeted therapies are discussed.

Of Mice and Melanoma: PDX System for Modeling Personalized Medicine

Targeted therapies have advanced the treatment options for cutaneous melanoma, but many patients will progress on drug. Patient-derived xenografts (PDX) can be used to recapitulate therapy-resistant tumors. Furthermore, PDX modeling can be utilized in combination with targeted sequencing and phosphoproteomic platforms, providing preclinical basis for second-line targeted inhibitor strategies. See related article by Krepler et al., p. 1592.

Extrinsic factors can mediate resistance to BRAF inhibition in central nervous system melanoma metastases

Here, we retrospectively review imaging of 68 consecutive unselected patients with BRAF V600-mutant metastatic melanoma for organ-specific response and progression on vemurafenib. Complete or partial responses were less often seen in the central nervous system (CNS) (36%) and bone (16%) compared to lung (89%), subcutaneous (83%), spleen (71%), liver (85%) and lymph nodes/soft tissue (83%), P < 0.001. CNS was also the most common site of progression. Based on this, we tested in vitro the efficacy of the BRAF inhibitors PLX4720 and dabrafenib in the presence of cerebrospinal fluid (CSF). Exogenous CSF dramatically reduced cell death in response to both BRAF inhibitors. Effective cell killing was restored by co-administration of a PI-3 kinase inhibitor. We conclude that the efficacy of vemurafenib is variable in different organs with CNS being particularly prone to resistance. Extrinsic factors, such as ERK- and PI3K-activating factors in CSF, may mediate BRAF inhibitor resistance in the CNS.

Targeting oncogenic BRAF and aberrant MAPK activation in the treatment of cutaneous melanoma

BRAF and MEK inhibitors, alone or in combination, are highly active in the 40% of patients with BRAF mutant metastatic melanoma. Despite this activity resistance often develops in patients treated with these agents. This review summarises the biology of the mitogen activated protein kinase (MAPK) pathway, with particular reference to the effects of BRAF and MEK inhibitors in BRAF mutant melanoma. The clinical and molecular predictors of response and mechanisms of resistance are discussed in detail along with the biological rationale and evidence for future treatment strategies in both MAPK inhibitor naïve and resistant BRAF mutant melanoma.

Correlating Surrogate Endpoints with Overall Survival at the Individual Patient Level in BRAFV600E-Mutated Metastatic Melanoma Patients Treated with Vemurafenib

PURPOSE

Surrogate endpoints are needed that correlate with overall survival (OS). We analyzed individual patient tumor data from a phase III trial of vemurafenib versus dacarbazine (BRIM3) to identify criteria for tumor measures that correlated with OS. Correlates were validated using a separate data set from a phase II trial of vemurafenib (BRIM2).

EXPERIMENTAL DESIGN

Deidentified tumor measurements and OS data from BRIM3 and from BRIM2 were analyzed. Target tumor measurement data and nontarget tumor data were available from pretreatment, weeks 6,12, and every 9 weeks thereafter. In the BRIM3 data set, associations of OS with both early tumor response (first 12 weeks) and time to progression (TTP) were assessed. Different definitions of response and progression were explored. Findings were validated using the BRIM2 data set.

RESULTS

Thresholds of early response were explored ranging from any degree of tumor shrinkage to 100% tumor shrinkage. Correlation was weak at all thresholds tested. TTP, however, was more strongly correlated with OS. The strongest correlation was seen when progression was defined as ≥50% increase in the sum of tumor diameters or appearance of new tumors. This was confirmed by similar analyses in the BRIM2 cohort.

CONCLUSIONS

TTP defined as ≥50% increase in the sum of tumor diameters or appearance of new tumors was more strongly associated with OS than early tumor shrinkage in melanoma patients treated with RAF inhibitor. In future trials, consideration should be given to replacing response rate with TTP or PFS as preferable clinical endpoints in early-phase studies.

The outcomes of Polish patients with advanced BRAF-positive melanoma treated with vemurafenib in a safety clinical trial

AIM OF THE STUDY

The BRAF inhibitor vemurafenib has improved progression-free survival and overall survival in patients with BRAFV600-mutation-positive metastatic melanoma. Here we present the results of an open-label safety study with vemurafenib in patients with metastatic melanoma enrolled in Polish oncological centres.

MATERIAL AND METHODS

Patients with untreated or previously treated Stage IIIC/IV BRAFV600 mutation-positive melanoma were treated with oral vemurafenib in an initial dose of 960 mg twice daily. Assessments for safety and efficacy were made every 28 days. For the survival analysis the Kaplan-Meier estimator was used with the log-rank tests for bivariate comparisons.

RESULTS

In total, 75 Polish patients were enrolled in the safety study across four centres. At data cut-off, 28 patients died (37%), mainly (26) due to disease progression; 33 (44%) patients continued vemurafenib after disease progression. The objective response rate was 46%, including two patients with a complete response and 29 with a partial response. Median progression-free survival was 7.4 months. The one-year overall survival rate was 61.9% (median overall survival was not reached). Seventy-three (97.3%) patients reported adverse events (AEs), and grade 3-5 toxicity was reported in 49.4% (37) patients. The most common AEs were: skin lesions (including rash and photosensitivity), arthralgia, and fatigue.

CONCLUSIONS

The overall safety profile and response rate of vemurafenib were comparable to those reported in previous studies of this drug. Our study confirmed the value of well-established prognostic features for overall survival, such as initial LDH (lactate dehydrogenase) level and AJCC staging.

Dabrafenib and its use in the treatment of metastatic melanoma

Approximately 50% of melanomas have mutations in the gene encoding BRAF. In recent years, new targeted therapies have transformed the landscape of metastatic melanoma treatment. Dabrafenib, a potent kinase inhibitor of mutated BRAF, has been showed to have high response rates with a rapid onset of response, as well as improved overall and progression-free survival when compared with chemotherapy. Dabrafenib in combination with trametinib, a MEK inhibitor, has demonstrated higher responses and improved clinical efficacy compared with monotherapy. Toxicity is distinct compared with chemotherapy but manageable. This article summarizes the pharmacology, key clinical trial data as well as practical experience with dabrafenib in clinical practice, and future directions.

Immune checkpoint inhibitors in melanoma

The potential to harness the power of the immune system and effectively treat patients with metastatic melanoma is finally being realized with the advent of immune checkpoint inhibitors. These new therapies herald a new era in the treatment of melanoma with the potential to produce very durable responses and possible cure for a subset of patients, though bring with them challenges including novel toxicities and nonconventional response patterns. This article reviews the currently available immune checkpoint inhibitors, potential biomarkers to predict response and promising investigational approaches including combination therapies.

Complete remission of metastatic melanoma upon BRAF inhibitor treatment - what happens after discontinuation?

Treatment with BRAF inhibitors (BRAFi) leads to complete remissions (CR) in 3-6% of patients with BRAF mutant metastatic melanoma. In cases of CR, it is unclear whether BRAFi therapy should be continued. We retrospectively analyzed the clinical course of patients with metastatic melanoma who discontinued BRAFi therapy after achieving a CR. In 12 patients, CR of metastatic melanoma was diagnosed after a median BRAFi treatment duration of 13 (range 0.3-32) months. Reasons for discontinuation were side effects in seven patients and patient demand in five patients. Six patients are still in CR after a median of 17 (range 2-26) months after discontinuation of BRAF inhibition. Six patients developed a melanoma recurrence after a median of 3 (range 2-17) months of discontinuation of BRAFi therapy. Subsequently, these patients were again treated with a BRAFi, which resulted in three CR, one stable disease, and one progressive disease; one patient could not be assessed. Melanoma patients achieving CR during BRAFi therapy represent a heterogeneous group. Discontinuation of BRAFi therapy after a CR has to be balanced carefully with the potential risk of nonresponding to BRAFi retreatment in the case of relapse.