Systemic Therapy Options for Patients With Unresectable Melanoma

Mechanisms of Melanoma Progression and Treatment Resistance: Role of Cancer Stem-like Cells

Melanoma is the third most common type of skin cancer, characterized by its heterogeneity and propensity to metastasize to distant organs. Melanoma is a heterogeneous tumor, composed of genetically divergent subpopulations, including a small fraction of melanoma-initiating cancer stem-like cells (CSCs) and many non-cancer stem cells (non-CSCs). CSCs are characterized by their unique surface proteins associated with aberrant signaling pathways with a causal or consequential relationship with tumor progression, drug resistance, and recurrence. Melanomas also harbor significant alterations in functional genes (BRAF, CDKN2A, NRAS, TP53, and NF1). Of these, the most common are the BRAF and NRAS oncogenes, with 50% of melanomas demonstrating the BRAF mutation (BRAFV600E). While the successful targeting of BRAFV600E does improve overall survival, the long-term efficacy of available therapeutic options is limited due to adverse side effects and reduced clinical efficacy. Additionally, drug resistance develops rapidly via mechanisms involving fast feedback re-activation of MAPK signaling pathways. This article updates information relevant to the mechanisms of melanoma progression and resistance and particularly the mechanistic role of CSCs in melanoma progression, drug resistance, and recurrence.

Efficacy of immunotherapy (Prolgolimab) and targeted therapy (Trametinib and Dabrafenib, Cobimetinib and Vemurafenib) in adult patients with metastatic or unresectable skin melanoma: matching-adjusted indirect comparison

Aim. To assess the comparative clinical efficacy of Prolgolimab monotherapy versus combination therapy with BRAF/MEK inhibitors (Dabrafenib and Trametinib, Vemurafenib and Cobimetinb) in adult patients with metastatic or unresectable skin melanoma implementing a matching-adjusted indirect comparison (MAIC). Materials and methods. We conducted a systematic search for randomized clinical trials of Prolgolimab, combinations of Dabrafenib and Trametinib, Cobimetinib and Vemurafenib. Unanchored MAIC was applied due to the absence of common comparator between trials. We determined effect modifiers based on an expert survey. The population from Prolgolimab studies was weighted using defined effect modifiers, followed by the approximation of survival curves. Results. Systematic literature search revealed 4 RCTs that met the inclusion criteria: MIRACULUM, coBRIM, combi-v and combi-d. To increase the power of prolgolimab comparison, data from the observational study FORA were included in evidence synthesis and combined with data from MIRACULUM. We selected M staging and the proportion of patients with elevated LDH levels as effect modifiers. No significant differences (all p0.05) were established between Prolgolimab and combination therapy with BRAF/MEK inhibitors for both OS after 1 year and PFS outcomes after 2 years from initiation. Discussion. Despite the inclusion of observational data and the limitations of adjusted indirect comparison method, the results of this analyses are consistent with both other comparisons of anti-PD1 inhibitors with BRAF/MEK inhibitors, and with real world data. It is necessary to recompare targeted therapy and immunotherapy after five-year follow-up period due to peculiarities of time of onset of their effect with the presence of a primary failure with a gradual exit to a long plateau on anti-PD1 inhibitors therapy. Conclusion. In these unanchored MAICs, Prolgolimab monotherapy showed comparable efficacy with combinations of BRAF/MEK inhibitors (Dabrafenib + Trametinib, Vemurafenib + Cobimetinib) in first line therapy of patients with metastatic or unresectable melanoma. This analysis may be relevant for clinical decision-making about the choice of the first line therapy for patients with BRAF mutation.

Nationwide Outcomes of Advanced Melanoma According to BRAFV600 Status

OBJECTIVE

The aim of this study was to evaluate treatment patterns and overall survival (OS) of patients with BRAFV600 wild-type and BRAFV600-mutant advanced melanoma in the Netherlands.

METHODS

We selected patients of 18 years and over, diagnosed between 2016 and 2017 with unresectable stage IIIC or IV melanoma, registered in the Dutch Melanoma Treatment Registry. To assess the association of BRAFV600-mutation status with OS we used the Cox proportional-hazards model.

RESULTS

A total of 642 BRAFV600 wild-type and 853 mutant patients were included in the analysis. Median OS did not differ significantly between both groups, 15.2 months (95% confidence interval [CI]: 13.2-19.2) versus 20.6 months (95% CI: 18.3-25.0). Survival rates at 6 and 12 months were significantly lower for BRAFV600 wild-type patients compared with BRAFV600-mutant patients, 72.0% (95% CI: 68.6-75.6) and 56.0% (95% CI: 52.2-60.0) versus 83.4% (95% CI: 80.9-85.9) and 65.7% (95% CI: 62.6-69.0). Two-year survival was not significantly different between both groups, 41.1% (95% CI: 37.2-45.3) versus 47.0% (95% CI: 43.6-60.6). Between 0 and 10 months, BRAFV600 wild-type patients had a decreased survival with a hazard ratio for OS of 2.00 (95% CI: 1.62-2.46) but this effect disappeared after 10 months. At 12 months, BRAFV600-mutant patients had started with second-line systemic treatment more often compared with BRAFV600 wild-type patients (50% vs. 19%).

CONCLUSION

These results suggest that advanced BRAFV600 wild-type melanoma patients have worse survival than BRAFV600-mutated patients during the first 10 months after diagnosis because of less available treatment options.

First-line BRAF/MEK inhibitors versus anti-PD-1 monotherapy in BRAFV600-mutant advanced melanoma patients: a propensity-matched survival analysis

BACKGROUND

Anti-PD-1 antibodies and BRAF/MEK inhibitors are the two main groups of systemic therapy in the treatment of BRAF^V600-mutant advanced melanoma. Until now, data are inconclusive on which therapy to use as first-line treatment. The aim of this study was to use propensity score matching to compare first-line anti-PD-1 monotherapy vs. BRAF/MEK inhibitors in advanced BRAF^V600-mutant melanoma patients.

METHODS

We selected patients diagnosed between 2014 and 2017 with advanced melanoma and a known BRAF^V600-mutation treated with first-line BRAF/MEK inhibitors or anti-PD-1 antibodies, registered in the Dutch Melanoma Treatment Registry. Patients were matched based on their propensity scores using the nearest neighbour and the optimal matching method.

RESULTS

Between 2014 and 2017, a total of 330 and 254 advanced melanoma patients received BRAF/MEK inhibitors and anti-PD-1 monotherapy as first-line systemic therapy. In the matched cohort, patients receiving anti-PD-1 antibodies as a first-line treatment had a higher median and 2-year overall survival compared to patients treated with first-line BRAF/MEK inhibitors, 42.3 months (95% CI: 37.3-NE) vs. 19.8 months (95% CI: 16.7-24.3) and 65.4% (95% CI: 58.1-73.6) vs. 41.7% (95% CI: 34.2-51.0).

CONCLUSIONS

Our data suggest that in the matched BRAF^V600-mutant advanced melanoma patients, anti-PD-1 monotherapy is the preferred first-line treatment in patients with relatively favourable patient and tumour characteristics.

Evolving impact of long-term survival results on metastatic melanoma treatment

Melanoma treatment has been revolutionized over the past decade. Long-term results with immuno-oncology (I-O) agents and targeted therapies are providing evidence of durable survival for a substantial number of patients. These results have prompted consideration of how best to define long-term benefit and cure. Now more than ever, oncologists should be aware of the long-term outcomes demonstrated with these newer agents and their relevance to treatment decision-making. As the first tumor type for which I-O agents were approved, melanoma has served as a model for other diseases. Accordingly, discussions regarding the value and impact of long-term survival data in patients with melanoma may be relevant in the future to other tumor types. Current findings indicate that, depending on the treatment, over 50% of patients with melanoma may gain durable survival benefit. The best survival outcomes are generally observed in patients with favorable prognostic factors, particularly normal baseline lactate dehydrogenase and/or a low volume of disease. Survival curves from melanoma clinical studies show a plateau at 3 to 4 years, suggesting that patients who are alive at the 3-year landmark (especially in cases in which treatment had been stopped) will likely experience prolonged cancer remission. Quality-of-life and mixture-cure modeling data, as well as metrics such as treatment-free survival, are helping to define the value of this long-term survival. In this review, we describe the current treatment landscape for melanoma and discuss the long-term survival data with immunotherapies and targeted therapies, discussing how to best evaluate the value of long-term survival. We propose that some patients might be considered functionally cured if they have responded to treatment and remained treatment-free for at least 2 years without disease progression. Finally, we consider that, while there have been major advances in the treatment of melanoma in the past decade, there remains a need to improve outcomes for the patients with melanoma who do not experience durable survival.

Validation of Circulating Tumor DNA Assays for Detection of Metastatic Melanoma

The detection of cell-free, circulating tumor DNA (ctDNA) in the blood of patients with solid tumors is often referred to as "liquid biopsy." ctDNA is particularly attractive as a candidate biomarker in the blood. It is relatively stable after blood collection, can be easily purified, and can be quantitatively measured with high sensitivity and specificity using advanced technologies. Current liquid biopsy research has focused on detecting and quantifying ctDNA to (1) diagnose and characterize mutations in a patient's cancer to help select the appropriate treatment; (2) predict clinical outcomes associated with different treatments; and (3) monitor the response and/or progression of a patient's disease. The diagnostic use of liquid biopsies is probably greatest in tumors where the difficulty and/or risk of obtaining a tissue specimen for molecular diagnostics is high (e.g., lung, colon). In metastatic melanoma, however, obtaining a tissue sample for molecular diagnostics is not typically a major obstacle to patient care plans; rather predicting treatment outcomes and monitoring a patient's disease course during therapy are considered the current priorities for this cancer type. In this chapter we describe an approach to the validation of ctDNA detection assays for melanoma, focusing primarily on analytical validation, and provide methods to guide the use of droplet digital PCR assays for measuring ctDNA levels in plasma samples.