Neoadjuvant BRAF-targeted therapy in regionally advanced and oligometastatic melanoma

A safety review of recently approved and late-stage trial treatments for metastatic melanoma: systemic and regional therapies

INTRODUCTION

Advanced melanoma accounts for the majority of skin cancer-associated deaths. Over the past 15 years, there has been a dramatic change in the treatment options and prognosis for patients with advanced melanoma secondary to the development of novel systemic immunotherapies (IO) and targeted therapies. In addition to these novel systemic therapies, regional therapies (intralesional and perfusional) also continue to play a major role in the management of these patients.

AREAS COVERED

In this article, we review recent updates in the management of advanced melanoma via Medline (PubMed) and Google Scholar, including recently published trials in the metastatic, adjuvant, and neoadjuvant settings. We also review recently published trials for regional therapies and discuss future directions in the management of patients with advanced melanoma.

EXPERT OPINION

A significant portion of patients with advanced melanoma will develop recurrent or progressive disease following treatment with IO or targeted therapy. Therefore, identifying not only the appropriate therapeutic agent but also the sequence and duration of treatment is pivotal for these patients.

Multicenter Experience with Neoadjuvant Therapy in Melanoma Highlights Heterogeneity in Contemporary Practice

OBJECTIVE

To determine the feasibility and impact of neoadjuvant therapy (NT) in patients who present with advanced melanoma amenable to surgical resection.

SUMMARY BACKGROUND DATA

Given current effective systemic therapy for melanoma, the use of NT is being explored in patients with advanced melanoma with disease amenable to surgical resection.

METHODS

Prospective data from 3 institutions was obtained in patients with clinically evident Stage III/IV melanoma who underwent NT. The primary objective was to compare recurrence-free survival between patients who had pathologic complete response (pCR) to those with persistent disease.

RESULTS

NT was offered to 45 patients, with 43 patients initiating various NT regimens including PD-1 antagonist (PD-1) therapy (N = 16), PD-1 plus ipilimumab (N = 10), BRAF/MEK inhibitor therapy (N = 14), a combination of those three (N = 1), and talimogene laherparepvec (TVEC) (N = 2). Thirty-two (74.1%) patients underwent surgery whereas 11 patients did not undergo surgery for these reasons: clinical CR (N = 7), progressive disease not amenable to resection (N = 3), and ongoing therapy (N = 1). 12 of 32 patients (37.5%) had pCR with these therapies: PD-1 (N = 4), PD-1 plus ipilimumab (N = 2), BRAF/MEK (N = 4), combination (N = 1), and TVEC (N = 1). At median follow-up of 16.4 months there was only 1 recurrence in the pCR group and patients with a pCR had significantly improved recurrence-free survival compared to patients without pCR (p = 0.004).

CONCLUSIONS

Despite variability in NT regimens across institutions, NT for melanoma is feasible and associated with improved prognosis in patients who achieve a pCR. Maximizing rates of pCR could improve prognosis for patients with advanced melanoma.

The future of targeted kinase inhibitors in melanoma

Melanoma is a cancer of the pigment-producing cells of the body and its incidence is rising. Targeted inhibitors that act against kinases in the MAPK pathway are approved for BRAF-mutant metastatic cutaneous melanoma and increase patients' survival. Response to these therapies is limited by drug resistance and is less durable than with immune checkpoint inhibition. Conversely, rare melanoma subtypes have few therapeutic options for advanced disease and MAPK pathway targeting agents show minimal anti-tumor effects. Nevertheless, there is a future for targeted kinase inhibitors in melanoma: in new applications such as adjuvant or neoadjuvant therapy and in novel combinations with immunotherapies or other targeted therapies. Pre-clinical studies continue to identify tumor dependencies and their corresponding actionable drug targets, paving the way for rational targeted kinase inhibitor combinations as a personalized medicine approach for melanoma.

18F-FDG PET/CT During Neoadjuvant Targeted Therapy in Prior Unresectable Stage III Melanoma Patients: Can (Early) Metabolic Imaging Predict Histopathologic Response or Recurrence?

PURPOSE

The aim of this study was to investigate whether 18F-FDG PET/CT can predict histopathological response or recurrence in BRAF-mutated unresectable locally advanced stage III melanoma treated with neoadjuvant BRAF/MEK inhibition followed by resection and the value of PET in detecting early recurrence after resection.

PATIENTS AND METHODS

Twenty BRAF-mutated, unresectable stage III melanoma patients received BRAF/MEK inhibitors before surgery. 18F-FDG PET/CT was performed at baseline and 2 and 8 weeks after initiation of therapy. After resection, PET/CT was performed at specific time points during 5 years of follow-up. Pathological response was assessed on the dissection specimen. Response monitoring was measured with SUVmax, SUVpeak, MATV, and TLG and according to EORTC and PERCIST criteria.

RESULTS

Pathological response was assessed in 18 patients. Nine patients (50%) had a pathologic complete or near-complete response, and 9 (50%) had a pathologic partial or no response. EORTC or PERCIST response measurements did not correspond with pathologic outcome. SUVmax, SUVpeak, MATV, and TLG at all time points and absolute or percentage change among the 3 initial time points did not differ between the groups.During follow-up, 8 of 17 patients with R0 resection developed a recurrence, 6 recurrences were detected with imaging only, 4 of which with PET/CT in less than 6 months after surgery. PET parameters before surgery did not predict recurrence.

CONCLUSIONS

Baseline 18F-FDG PET or PET response in previous unresectable stage III melanoma patients seems not useful to predict pathologic response after neoadjuvant BRAF/MEK inhibitors treatment. However, PET/CT seems valuable in detecting recurrence early after R0 resection.

Harnessing the immunotherapeutic potential of CDK4/6 inhibitors in melanoma: is timing everything?

CDK4/6 inhibitors (CDK4/6i) were developed as a cancer therapeutic on the basis of their tumor-intrinsic cytostatic potential, but have since demonstrated profound activity as immunomodulatory agents. While currently approved to treat hormone receptor-positive breast cancer, these inhibitors are under investigation in clinical trials as treatments for a range of cancer types, including melanoma. Melanoma is a highly immunogenic cancer, and has always been situated at the forefront of cancer immunotherapy development. Recent revelations into the immunotherapeutic activity of CDK4/6i, therefore, have significant implications for the utility of these agents as melanoma therapies. In recent studies, we and others have proven the immunomodulatory effects of CDK4/6i to be multifaceted and complex. Among the most notable effects, CDK4/6 inhibition induces transcriptional reprogramming in both tumor cells and immune cells to enhance tumor cell immunogenicity, promote an immune-rich tumor microenvironment, and skew T cell differentiation into a stem-like phenotype that is more amenable to immune checkpoint inhibition. However, in some contexts, the specific immunomodulatory effects of CDK4/6i may impinge on anti-tumor immunity. For example, CDK4/6 inhibition restricts optimal T cells expansion, and when used in combination with BRAF/MEK-targeted therapies, depletes immune-potentiating myeloid subsets from the tumor microenvironment. We propose that such effects, both positive and negative, may be mitigated or exacerbated by altering the CDK4/6i dosing regimen. Here, we discuss what the most recent insights mean for clinical trial design, and propose clinical considerations and strategies that may exploit the full immunotherapeutic potential of CDK4/6 inhibitors.

Efficacy of Neoadjuvant Targeted Therapy for Borderline Resectable III B-D or IV Stage BRAF V600 Mutation-Positive Melanoma

Simple Summary

Neoadjuvant therapy for locally advanced disease or potentially resectable metastatic melanoma is expected to improve operability and clinical outcomes over upfront surgery. 46 patients were treated with BRAFi/MEKi or BRAFi before surgery with 78% R0 resection. In patients with a major pathological response with no, or less than 10%, viable cells in the tumor, median DFS and PFS were significantly longer than in patients with a minor pathological response.

Abstract

Neoadjuvant therapy for locally advanced disease or potentially resectable metastatic melanoma is expected to improve operability and clinical outcomes over upfront surgery and adjuvant treatment as it is for sarcoma, breast, rectal, esophageal, or gastric cancers. Patients with locoregional recurrence after initial surgery and those with advanced regional lymphatic metastases are at a high risk of relapse and melanoma-related death. There is an unmet clinical need to improve the outcomes for such patients. Patients with resectable bulky stage III or resectable stage IV histologically confirmed melanoma were enrolled and received standard-dose BRAFi/MEKi for at least 12 weeks before feasible resection of the pre-therapy target and then received at least for the next 40 weeks further BRAFi/MEKi. Of these patients, 37 were treated with dabrafenib and trametinib, three were treated with vemurafenib and cobimetinib, five with vemurafenib, and one with dabrafenib alone. All patients underwent surgery with 78% microscopically margin-negative resection (R0) resection. Ten patients achieved a complete pathological response. In patients with a major pathological response with no, or less than 10%, viable cells in the tumor, median disease free survival and progression free survival were significantly longer than in patients with a minor pathological response. No patient discontinued neoadjuvant BRAFi/MEKi due to toxicity. BRAFi/MEKi pre-treatment did not result in any new specific complications of surgery. Fourteen patients experienced disease recurrence or progression during post-operative treatment. We confirmed that BRAFi/MEKi combination is an effective and safe regimen in the perioperative treatment of melanoma. Pathological response to neoadjuvant treatment may be considered as a surrogate biomarker of disease recurrence.

Neoadjuvant Cytoreductive Treatment With BRAF/MEK Inhibition of Prior Unresectable Regionally Advanced Melanoma to Allow Complete Surgical Resection, REDUCTOR: A Prospective, Single-arm, Open-label Phase II Trial

OBJECTIVE

To evaluate the potency of short-term neoadjuvant cytoreductive therapy with dabrafenib plus trametinib (BRAF and MEK inhibitor) to allow for radical surgical resection in patients with unresectable locally advanced melanoma.

SUMMARY BACKGROUND DATA

Approximately 5% of stage III melanoma patients presents with unresectable locally advanced disease, making standard of care with resection followed by adjuvant systemic therapy impossible. Although neoadjuvant targeted therapy has shown promising results in resectable stage III melanoma, its potency to enable surgical resection in patients with primarily unresectable locally advanced stage III melanoma is still unclear.

METHODS

In this prospective, single-arm, phase II trial, patients with unresectable BRAF-mutated locally advanced stage IIIC or oligometastatic stage IV melanoma were included. After 8 weeks of treatment with dabrafenib and trametinib, evaluation by positron emission tomography/computed tomography and physical examination were used to assess sufficient downsizing of the tumor to enable resection. The primary objective was the percentage of patients who achieved a radical (R0) resection.

RESULTS

Between August 2014 and March 2019, 21 patients (20/21 stage IIIC American Joint Committee on Cancer staging manual 7th edition) were included. Planned inclusion of 25 patients was not reached due to slow accrual and changing treatment landscape. Despite this, the predefined endpoint was successfully met. In 18/21 (86%) patients a resection was performed, of which 17 were R0 resections. At a median follow-up of 50 months (interquartile range 37.7-57.1 months), median recurrence-free survival was 9.9 months (95% confidence interval 7.52-not reached) in patients undergoing surgery.

CONCLUSIONS

This prospective, single-arm, open-label phase II trial, shows neoadjuvant dabrafenib plus trametinib as a potent cytoreductive treatment, allowing radical resection of metastases in 17/21 (81%) patients with prior unresectable locally advanced melanoma.

Neoadjuvant treatments in patients with high-risk resectable stage III/IV melanoma

Introduction: In recent years, the introduction of targeted therapy and immunotherapy into clinical practice has radically changed the management of advanced melanoma. More recently, these treatments also became the standard of care in the adjuvant setting. However, high-risk resectable stage III melanoma (i.e. with clinically detected regional lymph node involvement and/or satellites/in transit metastases) still has a high risk of relapse, even after adjuvant treatment, suggesting that the activity of immunotherapy and targeted therapy may play a relevant role in a neoadjuvant setting.Area covered: In this review, we discuss the results of the main clinical trials conducted in the neoadjuvant setting for patients with resectable stage III and stage IV melanoma, with a focus on the hot topics and a look at the future perspectives of the field.Expert opinion: The long-term effects of immunotherapy and the high response rate of targeted therapy provided the strong rationale to start neoadjuvant clinical trials for patients with resectable stage III and oligometastatic stage IV melanoma. Neoadjuvant therapy may play an important role not only for its possible impact on overall survival, but also as a predictive biological marker to allow for a more accurate personalization of adjuvant treatments.