F. Meier

Programmed cell death protein-1 (PD-1) inhibitor therapy in patients with advanced melanoma and preexisting autoimmunity or ipilimumab-triggered autoimmunity

AIMnProgrammed cell death protein 1 (PD-1) inhibitorsxa0are a common treatment strategy for metastatic melanoma and other tumour entities. Clinical trials usually exclude patients with preexisting autoimmune diseases, thus experience with PD-1 inhibitor (PD-1i) in this patient population is limited.nnnPATIENTS AND METHODSnMetastatic melanoma patients with preexisting autoimmune disorders or previous ipilimumab-triggered immune-related adverse events (irAE) undergoing treatment with PD-1i from seven German skin cancer centres were evaluated retrospectively with regard to flare of the preexisting autoimmunity and development of new, not preexisting irAE as well as response to PD-1i therapy.nnnRESULTSnIn total, 41 patients had either preexisting autoimmunity (n=19, group A, including two patients with additional ipilimumab-triggered autoimmune colitis) or ipilimumab-triggered irAE (n=22, group B). At PD-1i therapy initiation, six patients in group A and two patients in group B required immunosuppressive therapy. In group A, a flare of preexisting autoimmune disorders was seen in 42% of patients, new irAE in 16%. In group B, 4.5% of patients showed a flare of ipilimumab-triggered irAE and 23% new irAE.xa0All flares of preexisting autoimmune disorders or irAE were managed by immunosuppressive and/or symptomatic therapy and did not require termination of PD-1i therapy. tumour responses (32% in group A and 45% in group B) were unrelated to occurrence of autoimmunity.nnnCONCLUSIONnWhile preexisting autoimmunity commonly showed a flare during PD-1i therapy, a flare of ipilimumab-triggered irAE was rare. Response rates were above 30% and unrelated to irAE. PD-1i therapy can be considered in patients with autoimmune disorders depending on severity and activity of autoimmunity.

MAPK pathway in melanoma part II—secondary and adaptive resistance mechanisms to BRAF inhibition

BRAF mutation can be identified in about 45% of the patients with metastatic melanoma. In these patients, BRAF and MEK inhibitors are able to induce rapid responses and to prolong survival. However, a significant percentage of patients will develop resistance to targeted therapy and will have progressive disease. MAPK pathway is the most important pathway involved in BRAF/MEK inhibition resistance, particularly MAPK pathway reactivation. Resistance mechanisms can be classified as 1) primary or intrinsic characterised by no response to therapy, 2) secondary or acquired with MAPK pathway reactivation after a time of tumour regressionxa0and 3) as adaptive with initial response and early resistance. BRAF inhibition also alters the immune response. Several publications have described immune effects of BRAF inhibition in melanoma tumours, showing that combining targeted and immunotherapy can improve response, despite a possible cross-resistance. Here, we continue the review on resistance mechanisms to BRAF/MEK inhibition and focus on the secondary and adaptive mechanisms.

The mitogen-activated protein kinase pathway in melanoma part I – Activation and primary resistance mechanisms to BRAF inhibition

Mitogen-activated protein kinase (MAPK) pathway has an important role in normal cells and can be activated under physiological conditions. MAPK pathway activation is a fundamental step in several intracellular processesxa0requiring a sequential phosphorylation of the different pathway components. In normal cells, when MAPK pathway activation occurs, it leads to cell growth and differentiation. In order to prevent persistent MAPK pathway activation, physiological upstream negative feedbackxa0also takes place. In cells harbouring BRAFV600 mutations, the process leading to MAPK pathway activation is different, and the negative physiological feedback does not existxa0thus leading to permanent MAPK pathway activation, which ultimately can lead to uncontrolled proliferation. Targeted therapy with rapidly accelerated fibrosarcoma - B (BRAF) and/or mitogen-activated extracellular signal-regulated kinase kinase (MEK) inhibitors is indicated in patients with metastatic melanoma harboring BRAFV600 mutations. However, several different resistance mechanisms to this therapy were identified. In this review, we focus on primary or intrinsic resistance mechanisms to BRAF and MEK inhibition. In this setting, although a BRAF mutation is identified, there is no response to treatment with either BRAF or MEK inhibitor.

Systemic therapy of metastatic melanoma

For patients with metastatic melanoma, there are currently several effective therapeutic options. The BRAF inhibitors vemurafenib and dabrafenib are characterized by rapid tumor control and high response rates. In combination with one of the two MEK inhibitors trametinib and cobimetinib, they achieve response rates (CR + PR, complete plus partial remissions) of 70 %, while delaying the development of treatment resistance, as well as a median overall survival of > 2 years with tolerable side effects.

A Nexus Consisting of Beta-Catenin and Stat3 Attenuates BRAF Inhibitor Efficacy and Mediates Acquired Resistance to Vemurafenib

Acquired resistance to second generation BRAF inhibitors (BRAFis), like vemurafenib is limiting the benefits of long term targeted therapy for patients with malignant melanomas that harbor BRAF V600 mutations. Since many resistance mechanisms have been described, most of them causing a hyperactivation of the MAPK- or PI3K/AKT signaling pathways, one potential strategy to overcome BRAFi resistance in melanoma cells would be to target important common signaling nodes. Known factors that cause secondary resistance include the overexpression of receptor tyrosine kinases (RTKs), alternative splicing of BRAF or the occurrence of novel mutations in MEK1 or NRAS. In this study we show that β-catenin is stabilized and translocated to the nucleus in approximately half of the melanomas that were analyzed and which developed secondary resistance towards BRAFi. We further demonstrate that β-catenin is involved in the mediation of resistance towards vemurafenib in vitro and in vivo. Unexpectedly, β-catenin acts mainly independent of the TCF/LEF dependent canonical Wnt-signaling pathway in resistance development, which partly explains previous contradictory results about the role of β-catenin in melanoma progression and therapy resistance. We further demonstrate that β-catenin interacts with Stat3 after chronic vemurafenib treatment and both together cooperate in the acquisition and maintenance of resistance towards BRAFi.

Prognostic factors and outcomes in metastatic uveal melanoma treated with programmed cell death-1 or combined PD-1/cytotoxic T-lymphocyte antigen-4 inhibition

BACKGROUNDnUveal melanoma (UM) is an ocular malignancy with high potential for metastatic spread. In contrast to cutaneous melanoma, immunotherapy has not yet shown convincing efficacy in patients with UM. Combined immune checkpoint blockade with checkpoint programmed cell death-1 (PD-1) and checkpoint cytotoxic T-lymphocyte antigen-4 (CTLA-4) inhibition has not been systematically assessed for UM to date.nnnPATIENTS AND METHODSnPatients with metastatic UM treated with either PD-1 inhibitor monotherapy or combined PD-1 inhibitor and ipilimumab (an anti-CTLA-4 monoclonal antibody) were included from 20 German skin cancer centres. Records from 96 cases were analysed for treatment outcomes. Clinical and blood parameters associated with overall survival (OS) or treatment response were identified with multivariate Cox regression and binary logistic regression.nnnRESULTSnEighty-six patients were treated with PD-1 inhibitors only (nxa0=xa054 for pembrolizumab, nxa0=xa032 for nivolumab) with a centrally confirmed response rate of 4.7%. Median OS was 14 months for pembrolizumab-treated and 10 months for nivolumab-treated patients (pxa0=xa00.765). Fifteen patients were treated with combined immune checkpoint blockade with partial response observed in two cases. Median OS was not reached in this group. Multivariate Cox regression identified Eastern Cooperative Oncology Group (ECOG) performance status (pxa0=xa00.002), elevated serum levels of lactate dehydrogenase (LDH) (pxa0=xa00.002) and C-reactive protein (CRP) (pxa0=xa00.001), and a relative eosinophil count (REC) <1.5% (pxa0=xa00.002) as independent risk factors for poor survival. Patients with elevated CRP and LDH and a REC <1.5% were at highest risk for disease progression and death (pxa0=xa00.001).nnnCONCLUSIONSnBlood markers predict survival in metastatic UM treated with immune checkpoint blockade. Normal serum levels of LDH and CRP and a high REC may help identify patients with better prognosis.

Prognostic factors and treatment outcomes in 444 patients with mucosal melanoma

BACKGROUNDnMucosal melanoma (MM) is a rare but diverse cancer entity. Prognostic factors are not well established for Caucasians with MM.nnnPATIENTS AND METHODSnWe analysed the disease course of 444 patients from 15 German skin cancer centres. Disease progression was determined with the cumulative incidence function. Survival times were estimated with the Kaplan-Meier method. Prognostic parameters were identified with multivariate Cox regression analysis.nnnRESULTSnCommon anatomic sites of primary tumours were head and neck (MMHN, 37.2%), female genital tract (MMFG, 30.4%) and anorectal region (MMAN, 21.8%). MMAN patients showed the highest vertical tumour thickness (pxa0=xa00.001), had a more advanced nodal status (pxa0=xa00.014) and a higher percentage of metastatic disease (pxa0=xa00.001) at diagnosis. Mutations of NRAS (13.8%), KIT (8.6%)xa0and BRAF (6.4%) were evenly distributed across all tumour site groups. Local relapses were observed in 32.4% and most commonly occurred in the MMHN group (pxa0=xa00.016). Male gender (pxa0=xa00.047), advanced tumour stage (pxa0=xa00.001), nodal disease (pxa0=xa00.001)xa0and incomplete resection status (pxa0=xa00.001) were independent risk factors for disease progression. Overall survival (OS) was highest in the MMFG group (pxa0=xa00.030) and in patients without ulceration (pxa0=xa00.004). Multivariate risk factors for OS were M stage at diagnosis (pxa0=xa00.002) and incomplete resection of the primary tumour (pxa0=xa00.001).nnnCONCLUSIONnIn this large series of MM patients in a European population, anorectal MM was associated with the poorest prognosis.

Hirnmetastasen des malignen Melanoms

The majority of patients with metastatic melanoma will develop brain metastases, which are the most common cause of death. Until recently, local therapies (e.u2009g., neurosurgery, radiotherapy) were the only options for brain metastases; however, effective systemic treatment options are now available. Upon suspicion of brain metastases, diagnostic staging with brain MRI and a neurological investigation are indicated. Prognostic factors such as number of cerebral metastases and symptoms, serum lactate dehydrogenase and S‑100 levels, extracerebral metastases, and ECOG status are considered during therapeutic planning. Treatment planning and therapeutic interventions should be based on an interdisciplinary and multimodal approach. Established treatments for singular brain metastases are neurosurgical resection and stereotactic radiotherapy, which can prolong survival. In patients with asymptomatic BRAF V600E-mutant brain metastases, the BRAF inhibitors dabrafenib, vemurafenib, and immunotherapy with ipilimumab are used. In the case of multiple symptomatic brain metastases, palliative whole-brain radiotherapy is used for treatment, although it has failed to show an overall survival benefit. Increased intracranial pressure and epileptic seizures are addressed with corticosteroids and anticonvulsants. Current clinical studies for melanoma patients with brain metastases are investigating new treatment options such as PD-1 antibodies, combined ipilimumab and nivolumab, combined BRAF inhibitors and MEK inhibitors, and stereotactic radiation in combination with immunotherapy or targeted therapy.ZusammenfassungHirnmetastasen treten bei der Mehrheit der Patienten mit metastasiertem Melanom auf und sind die häufigste Todesursache. Bis vor Kurzem war die Lokaltherapie die einzige Option für die Kontrolle von Hirnmetastasen. Inzwischen stehen wirksame systemische Therapieoptionen zur Verfügung. Bei Verdacht auf Hirnmetastasen sind eine Staging-Diagnostik mit Craniale Magnetresonanztomographie (cMRT) sowie eine neurologische Untersuchung indiziert. Für die Therapieplanung sollten prognostische Faktoren wie Anzahl und Symptomatik der zerebralen Metastasen, der LDH- und S100-Wert im Serum, die extrazerebrale Metastasierung sowie der ECOG (Eastern Cooperative Oncology Group)-Status einbezogen werden. Die Therapieentscheidung bzw. -durchführung sollte interdisziplinär bzw. multimodal erfolgen. Bei singulären Hirnmetastasen sind die neurochirurgische Resektion und die stereotaktische Radiatio etabliert. Das Behandlungsspektrum hat sich durch die Neuzulassung von wirksamen Immuntherapien (CTLA-4- und PD-1-Antikörper) sowie zielgerichteten Therapien (BRAF-und MEK-Inhibitoren) erheblich erweitert. Die palliative Ganzhirnradiatio wird bei multiplen symptomatischen Hirnmetastasen eingesetzt, wobei bisher kein signifikanter Vorteil für das Gesamtüberleben gezeigt werden konnte. Bei erhöhtem intrakraniellem Druck und epileptischen Anfällen sind Kortikosteroide und Antikonvulsiva indiziert. In aktuellen klinischen Studien werden für Melanompatienten mit Hirnmetastasen neue Therapieoptionen wie PD-1-Antikörper, Ipilimumab plus Nivolumab, BRAF-Inhibitoren plus MEK-Inhibitoren sowie stereotaktische Radiatio in Kombination mit Immuntherapie bzw. zielgerichteter Therapie untersucht.AbstractThe majority of patients with metastatic melanoma will develop brain metastases, which are the most common cause of death. Until recently, local therapies (e.u2009g., neurosurgery, radiotherapy) were the only options for brain metastases; however, effective systemic treatment options are now available. Upon suspicion of brain metastases, diagnostic staging with brain MRI and a neurological investigation are indicated. Prognostic factors such as number of cerebral metastases and symptoms, serum lactate dehydrogenase and S‑100 levels, extracerebral metastases, and ECOG status are considered during therapeutic planning. Treatment planning and therapeutic interventions should be based on an interdisciplinary and multimodal approach. Established treatments for singular brain metastases are neurosurgical resection and stereotactic radiotherapy, which can prolong survival. In patients with asymptomatic BRAF V600E-mutant brain metastases, the BRAF inhibitors dabrafenib, vemurafenib, and immunotherapy with ipilimumab are used. In the case of multiple symptomatic brain metastases, palliative whole-brain radiotherapy is used for treatment, although it has failed to show an overall survival benefit. Increased intracranial pressure and epileptic seizures are addressed with corticosteroids and anticonvulsants. Current clinical studies for melanoma patients with brain metastases are investigating new treatment options such as PD-1 antibodies, combined ipilimumab and nivolumab, combined BRAF inhibitors and MEK inhibitors, and stereotactic radiation in combination with immunotherapy or targeted therapy.

[Melanoma brain metastases : Treatment options].

The majority of patients with metastatic melanoma will develop brain metastases, which are the most common cause of death. Until recently, local therapies (e.u2009g., neurosurgery, radiotherapy) were the only options for brain metastases; however, effective systemic treatment options are now available. Upon suspicion of brain metastases, diagnostic staging with brain MRI and a neurological investigation are indicated. Prognostic factors such as number of cerebral metastases and symptoms, serum lactate dehydrogenase and S‑100 levels, extracerebral metastases, and ECOG status are considered during therapeutic planning. Treatment planning and therapeutic interventions should be based on an interdisciplinary and multimodal approach. Established treatments for singular brain metastases are neurosurgical resection and stereotactic radiotherapy, which can prolong survival. In patients with asymptomatic BRAF V600E-mutant brain metastases, the BRAF inhibitors dabrafenib, vemurafenib, and immunotherapy with ipilimumab are used. In the case of multiple symptomatic brain metastases, palliative whole-brain radiotherapy is used for treatment, although it has failed to show an overall survival benefit. Increased intracranial pressure and epileptic seizures are addressed with corticosteroids and anticonvulsants. Current clinical studies for melanoma patients with brain metastases are investigating new treatment options such as PD-1 antibodies, combined ipilimumab and nivolumab, combined BRAF inhibitors and MEK inhibitors, and stereotactic radiation in combination with immunotherapy or targeted therapy.ZusammenfassungHirnmetastasen treten bei der Mehrheit der Patienten mit metastasiertem Melanom auf und sind die häufigste Todesursache. Bis vor Kurzem war die Lokaltherapie die einzige Option für die Kontrolle von Hirnmetastasen. Inzwischen stehen wirksame systemische Therapieoptionen zur Verfügung. Bei Verdacht auf Hirnmetastasen sind eine Staging-Diagnostik mit Craniale Magnetresonanztomographie (cMRT) sowie eine neurologische Untersuchung indiziert. Für die Therapieplanung sollten prognostische Faktoren wie Anzahl und Symptomatik der zerebralen Metastasen, der LDH- und S100-Wert im Serum, die extrazerebrale Metastasierung sowie der ECOG (Eastern Cooperative Oncology Group)-Status einbezogen werden. Die Therapieentscheidung bzw. -durchführung sollte interdisziplinär bzw. multimodal erfolgen. Bei singulären Hirnmetastasen sind die neurochirurgische Resektion und die stereotaktische Radiatio etabliert. Das Behandlungsspektrum hat sich durch die Neuzulassung von wirksamen Immuntherapien (CTLA-4- und PD-1-Antikörper) sowie zielgerichteten Therapien (BRAF-und MEK-Inhibitoren) erheblich erweitert. Die palliative Ganzhirnradiatio wird bei multiplen symptomatischen Hirnmetastasen eingesetzt, wobei bisher kein signifikanter Vorteil für das Gesamtüberleben gezeigt werden konnte. Bei erhöhtem intrakraniellem Druck und epileptischen Anfällen sind Kortikosteroide und Antikonvulsiva indiziert. In aktuellen klinischen Studien werden für Melanompatienten mit Hirnmetastasen neue Therapieoptionen wie PD-1-Antikörper, Ipilimumab plus Nivolumab, BRAF-Inhibitoren plus MEK-Inhibitoren sowie stereotaktische Radiatio in Kombination mit Immuntherapie bzw. zielgerichteter Therapie untersucht.AbstractThe majority of patients with metastatic melanoma will develop brain metastases, which are the most common cause of death. Until recently, local therapies (e.u2009g., neurosurgery, radiotherapy) were the only options for brain metastases; however, effective systemic treatment options are now available. Upon suspicion of brain metastases, diagnostic staging with brain MRI and a neurological investigation are indicated. Prognostic factors such as number of cerebral metastases and symptoms, serum lactate dehydrogenase and S‑100 levels, extracerebral metastases, and ECOG status are considered during therapeutic planning. Treatment planning and therapeutic interventions should be based on an interdisciplinary and multimodal approach. Established treatments for singular brain metastases are neurosurgical resection and stereotactic radiotherapy, which can prolong survival. In patients with asymptomatic BRAF V600E-mutant brain metastases, the BRAF inhibitors dabrafenib, vemurafenib, and immunotherapy with ipilimumab are used. In the case of multiple symptomatic brain metastases, palliative whole-brain radiotherapy is used for treatment, although it has failed to show an overall survival benefit. Increased intracranial pressure and epileptic seizures are addressed with corticosteroids and anticonvulsants. Current clinical studies for melanoma patients with brain metastases are investigating new treatment options such as PD-1 antibodies, combined ipilimumab and nivolumab, combined BRAF inhibitors and MEK inhibitors, and stereotactic radiation in combination with immunotherapy or targeted therapy.

In vitro models of melanoma

Despite remarkable efforts, metastatic melanoma still presents with significant mortality. Increasing knowledge about signal transduction pathways and immune checkpoints being involved in melanoma progression has led to the development of more effective targeted drugs and immune checkpoint inhibitors. Still, metastatic melanoma remains a life-threatening disease because tumors are resistant or develop resistance regaining tumorigenic capacity. Although genetically engineered mouse models for metastatic melanoma have been developed, cellular models that reliably mimic the human disease and are suitable for studying mechanisms of therapeutic obstacles are requested that translate the findings from basic cellular research into clinical applications. The following chapter aims to introduce and discuss 3D cell-based in vitro models that recapitulate both the architecture and multicellular complexity of an organ/tumor in vivo but at the same time accommodate systematic experimental intervention. Those models may facilitate efforts to improve therapeutic outcomes for malignant melanoma by providing a platform for the investigation of cytotoxic treatments and tailored therapies in a more physiological setting.