Neutralization of the CD95 ligand by APG101 inhibits invasion of glioma cells in vitro

CAN008 prolongs overall survival in patients with newly diagnosed GBM characterized by high tumor mutational burden

BACKGROUND

A previous phase 1 dose-escalation study in Taiwan indicated CAN008 (asunercept) with standard concurrent chemoradiotherapy (CCRT) improved progression-free survival (PFS) in newly diagnosed glioblastoma (GBM) patients. This study evaluates the efficacy of CAN008 in promoting overall survival (OS) and identifies genetic alterations associated with treatment responses.

METHODS

We compared OS of 5-year follow-ups from 9 evaluable CAN008 cohort patients (6 received high-dose and 3 received low-dose) to a historical Taiwanese GBM cohort with 164 newly diagnosed patients. CAN008 treatment response-associated genetic alterations were identified by whole-exome sequencing and comparing variant differences between response groups. Associations among patient survival, tumor mutational burden (TMB), and genetic alterations were analyzed using CAN008 cohort and TCGA-GBM dataset.

RESULTS

OS for high-dose CAN008 patients at 2 and 5 years was 83% and 67%, respectively, and 40.1% and 8.8% for the historical GBM cohort, respectively. Better OS was observed in the high-dose CAN008 cohort (without reaching the median survival) than the historical GBM cohort (median OS: 20 months; p = 0.0103). Five high-dose CAN008 patients were divided into good and poor response groups based on their PFS. A higher variant count and TMB were observed in good response patients, whereas no significant association was observed between TMB and patient survival in the newly diagnosed TCGA-GBM dataset, suggesting TMB may modulate patient CAN008 response.

CONCLUSION

CAN008 combined with standard CCRT treatment prolonged the PFS and OS of newly diagnosed GBM patients compared to standard therapy alone. Higher treatment efficacy was associated with higher TMB.

Immunostaining protocol for infiltrating brain cancer spheroids for light-sheet imaging

Glioblastoma tumors form in brains' white matter and are fast-growing and aggressive. Poor prognosis is the result of therapeutic resistance and infiltrating growth into the surrounding brain. Here we present a protocol for the detection of the cytoskeleton intermediate filament, vimentin, in cells at the proliferating spheroid surface. By combining a classical invasion assay with immunofluorescence and light-sheet imaging, we find that it is exactly these cytoskeleton-reinforcing cells on the spheroid's surface that will start the infiltration. We anticipate our results to be the starting point of more sophisticated investigation of anti-cancer drug effects on cytoskeleton reorganisation.

The dual role of the CD95 and CD95L signaling pathway in glioblastoma

Binding of CD95, a cell surface death receptor, to its homologous ligand CD95L, transduces a cascade of downstream signals leading to apoptosis crucial for immune homeostasis and immune surveillance. Although CD95 and CD95L binding classically induces programmed cell death, most tumor cells show resistance to CD95L-induced apoptosis. In some cancers, such as glioblastoma, CD95-CD95L binding can exhibit paradoxical functions that promote tumor growth by inducing inflammation, regulating immune cell homeostasis, and/or promoting cell survival, proliferation, migration, and maintenance of the stemness of cancer cells. In this review, potential mechanisms such as the expression of apoptotic inhibitor proteins, decreased activity of downstream elements, production of nonapoptotic soluble CD95L, and non-apoptotic signals that replace apoptotic signals in cancer cells are summarized. CD95L is also expressed by other types of cells, such as endothelial cells, polymorphonuclear myeloid-derived suppressor cells, cancer-associated fibroblasts, and tumor-associated microglia, and macrophages, which are educated by the tumor microenvironment and can induce apoptosis of tumor-infiltrating lymphocytes, which recognize and kill cancer cells. The dual role of the CD95-CD95L system makes targeted therapy strategies against CD95 or CD95L in glioblastoma difficult and controversial. In this review, we also discuss the current status and perspective of clinical trials on glioblastoma based on the CD95-CD95L signaling pathway.

CRISPR/Cas9-mediated abrogation of CD95L/CD95 signaling-induced glioma cell growth and immunosuppression increases survival in murine glioma models

PURPOSE

Glioblastoma is the most common brain tumor in adults and is virtually incurable. Therefore, new therapeutic strategies are urgently needed. Over the last decade, multiple growth-promoting functions have been attributed to CD95, a prototypic death receptor well characterized as an apoptosis mediator upon CD95L engagement. Strategic targeting of non-apoptotic or apoptotic CD95 signaling may hold anti-glioblastoma potential. Due to its antithetic nature, understanding the constitutive role of CD95 signaling in glioblastoma is indispensable.

METHODS

We abrogated constitutive Cd95 and Cd95l gene expression by CRISPR/Cas9 in murine glioma models and characterized the consequences of gene deletion in vitro and in vivo.

RESULTS

Expression of canonical CD95 but not CD95L was identified in mouse glioma cells in vitro. Instead, a soluble isoform-encoding non-canonical Cd95l transcript variant was detected. In vivo, an upregulation of the membrane-bound canonical CD95L form was revealed. Cd95 or Cd95l gene deletion decreased cell growth in vitro. The growth-supporting role of constitutive CD95 signaling was validated by Cd95 re-transfection, which rescued growth. In vivo, Cd95 or Cd95l gene deletion prolonged survival involving tumor-intrinsic and immunological mechanisms in the SMA-497 model. In the GL-261 model, that expresses no CD95, only CD95L gene deletion prolonged survival, involving a tumor-intrinsic mechanism.

CONCLUSION

Non-canonical CD95L/CD95 interactions are growth-promoting in murine glioma models, and glioma growth and immunosuppression may be simultaneously counteracted by Cd95l gene silencing.

CD95 gene deletion may reduce clonogenic growth and invasiveness of human glioblastoma cells in a CD95 ligand-independent manner

CD95 (Fas/APO-1) is a multifunctional cell surface receptor with antithetic roles. First described to mediate cell death, interactions of CD95 with its natural ligand, CD95L, have also been described to induce tumor-promoting signaling leading to proliferation, invasion and stem cell maintenance, mainly in cancer cells that are resistant to CD95-mediated apoptosis. While activation of CD95-mediated apoptosis in cancer cells may not be clinically practicable due to toxicity, inhibition of tumor-promoting CD95 signaling holds therapeutic potential. In the present study, we characterized CD95 and CD95L expression in human glioma-initiating cells (GIC), a glioblastoma cell population with stem cell features, and investigated the consequences of CRISPR-Cas9-mediated CD95 or CD95L gene deletion. In vitro, GIC expressed CD95 but not CD95L and were sensitive to CD95-mediated apoptosis. Upon genetic deletion of CD95, GIC acquired resistance to CD95L-induced apoptosis but exhibited inferior clonogenic growth, sphere-forming capacity, and invasiveness compared with control cells, suggesting the existence of CD95L-independent constitutive CD95 signaling with tumor-promoting properties in GIC. In vivo, GIC expressed CD95 and a non-canonical form of CD95L lacking the CD95-binding region. CD95 genetic deletion did not prolong survival in immunocompromised GIC-bearing mice. Altogether, these data indicate that canonical CD95L may not be expressed in human GIC and suggest the existence of a CD95L-independent CD95-signaling pathway that maintains some malignancy traits of GIC. The lack of altered survival of tumor-bearing mice after genetic deletion of CD95 suggests that CD95 signaling is not essential to maintain the growth of human GIC xenografted into the brains of nude mice. The ligand-independent tumor-promoting role of constitutive CD95 in our GIC models in vitro highlights the complexity and challenges associated with targeting CD95 with therapeutic intent.

Therapeutic approaches targeting CD95L/CD95 signaling in cancer and autoimmune diseases

Cell death plays a pivotal role in the maintenance of tissue homeostasis. Key players in the controlled induction of cell death are the Death Receptors (DR). CD95 is a prototypic DR activated by its cognate ligand CD95L triggering programmed cell death. As a consequence, alterations in the CD95/CD95L pathway have been involved in several disease conditions ranging from autoimmune diseases to inflammation and cancer. CD95L-induced cell death has multiple roles in the immune response since it constitutes one of the mechanisms by which cytotoxic lymphocytes kill their targets, but it is also involved in the process of turning off the immune response. Furthermore, beyond the canonical pro-death signals, CD95L, which can be membrane-bound or soluble, also induces non-apoptotic signaling that contributes to its tumor-promoting and pro-inflammatory roles. The intent of this review is to describe the role of CD95/CD95L in the pathophysiology of cancers, autoimmune diseases and chronic inflammation and to discuss recently patented and emerging therapeutic strategies that exploit/block the CD95/CD95L system in these diseases.

Glycomaterials to Investigate the Functional Role of Aberrant Glycosylation in Glioblastoma

Glioblastoma (GBM) is a stage IV astrocytoma that carries a dismal survival rate of ≈10 months postdiagnosis and treatment. The highly invasive capacity of GBM and its ability to escape therapeutic challenges are key factors contributing to the poor overall survival rate. While current treatments aim to target the cancer cell itself, they fail to consider the significant role that the GBM tumor microenvironment (TME) plays in promoting tumor progression and therapeutic resistance. The GBM tumor glycocalyx and glycan-rich extracellular matrix (ECM), which are important constituents of the TME have received little attention as therapeutic targets. A wide array of aberrantly modified glycans in the GBM TME mediate tumor growth, invasion, therapeutic resistance, and immunosuppression. Here, an overview of the landscape of aberrant glycan modifications in GBM is provided, and the design and utility of 3D glycomaterials are discussed as a tool to evaluate glycan-mediated GBM progression and therapeutic efficacy. The development of alternative strategies to target glycans in the TME can potentially unveil broader mechanisms of restricting tumor growth and enhancing the efficacy of tumor-targeting therapeutics.

Safety and tolerability of asunercept plus standard radiotherapy/temozolomide in Asian patients with newly-diagnosed glioblastoma: a phase I study

Asunercept (company code APG101 [Apogenix AG]; company code CAN008 [CANbridge Pharmaceuticals]) is a novel glycosylated fusion protein that has shown promising effectiveness in glioblastoma. This Phase I study was initiated to evaluate the tolerability and safety of asunercept in combination with standard radiotherapy and temozolomide (RT/TMZ) in Asian patients with newly diagnosed glioblastoma. This was the Phase I portion of a Phase I/II open label, multicenter trial of asunercept plus standard RT/TMZ. Adults with newly-diagnosed glioblastoma received surgical resection followed by standard RT/TMZ plus asunercept 200 mg/week (Cohort 1) or 400 mg/week (Cohort 2) by 30-min IV infusion. The primary endpoint was the safety and tolerability of asunercept during concurrent asunercept and RT/TMZ; dose-limiting toxicities were observed for each dose. Secondary endpoints included pharmacokinetics (PK) and 6-month progression-free survival (PFS6). All patients (Cohort 1, n = 3; Cohort 2, n = 7) completed ≥ 7 weeks of asunercept treatment. No DLTs were experienced. Only one possibly treatment-related treatment emergent adverse event (TEAE), Grade 1 gingival swelling, was observed. No Grade > 3 TEAEs were reported and no TEAE led to treatment discontinuation. Systemic asunercept exposure increased proportionally with dose and showed low inter-patient variability. The PFS6 rate was 33.3% and 57.1% for patients in Cohort 1 and 2, respectively. Patients in Cohort 2 maintained a PFS rate of 57.1% at Month 12. Adding asunercept to standard RT/TMZ was safe and well tolerated in patients with newly-diagnosed glioblastoma and 400 mg/week resulted in encouraging efficacy.

Trial registration NCT02853565, August 3, 2016.

Single-cell tracking reveals super-spreading brain cancer cells with high persistence

Cell migration is a fundamental characteristic of vital processes such as tissue morphogenesis, wound healing and immune cell homing to lymph nodes and inflamed or infected sites. Therefore, various brain defect diseases, chronic inflammatory diseases as well as tumor formation and metastasis are associated with aberrant or absent cell migration. We embedded multicellular brain cancer spheroids in Matrigel™ and utilized single-particle tracking to extract the paths of cells migrating away from the spheroids. We found that - in contrast to local invasion - single cell migration is independent of Matrigel™ concentration and is characterized by high directionality and persistence. Furthermore, we identified a subpopulation of super-spreading cells with >200-fold longer persistence times than the majority of cells. These results highlight yet another aspect of cell heterogeneity in tumors.

CD95L and Anti-Tumor Immune Response: Current Understanding and New Evidence

The ability of FasL/CD95L to induce apoptosis in various Fas/CD95-expressing cells has been described in the context of hematopoiesis or thymic elimination of self-reactive T cells and resolution of an acute immune response under physiological conditions. At the same time, non-apoptotic CD95 activation is widely described in cancer and shown to stimulate invasiveness of cancer cells, promote cancer progression as well as stemness of cancer cells. This paper puts emphasis on the evolving understanding of expression and the non-apoptotic activities of the CD95/CD95L signaling pathway on the function of tumor cells, tumor microenvironment and immune cells. The emerging evidence to support the role of CD95/CD95L signaling in the anti-tumor immune response will be presented in the context of various malignancies and the modalities of potential therapeutic interventions via selective CD95L inhibition in combination with traditional interventions such as RT, chemotherapy and immune checkpoint inhibitors.

In vitro biomimetic models for glioblastoma-a promising tool for drug response studies

The poor response of glioblastoma to current treatment protocols is a consequence of its intrinsic drug resistance. Resistance to chemotherapy is primarily associated with considerable cellular heterogeneity, and plasticity of glioblastoma cells, alterations in gene expression, presence of specific tumor microenvironment conditions and blood-brain barrier. In an attempt to successfully overcome chemoresistance and better understand the biological behavior of glioblastoma, numerous tri-dimensional (3D) biomimetic models were developed in the past decade. These novel advanced models are able to better recapitulate the spatial organization of glioblastoma in a real time, therefore providing more realistic and reliable evidence to the response of glioblastoma to therapy. Moreover, these models enable the fine-tuning of different tumor microenvironment conditions and facilitate studies on the effects of the tumor microenvironment on glioblastoma chemoresistance. This review outlines current knowledge on the essence of glioblastoma chemoresistance and describes the progress achieved by 3D biomimetic models. Moreover, comprehensive literature assessment regarding the influence of 3D culturing and microenvironment mimicking on glioblastoma gene expression and biological behavior is also provided. The contribution of the blood-brain barrier as well as the blood-tumor barrier to glioblastoma chemoresistance is also reviewed from the perspective of 3D biomimetic models. Finally, the role of mathematical models in predicting 3D glioblastoma behavior and drug response is elaborated. In the future, technological innovations along with mathematical simulations should create reliable 3D biomimetic systems for glioblastoma research that should facilitate the identification and possibly application in preclinical drug testing and precision medicine.

Longitudinal analysis of quality of life following treatment with Asunercept plus reirradiation versus reirradiation in progressive glioblastoma patients

PURPOSE

Glioblastoma is an aggressive malignant cancer of the central nervous system, with disease progression associated with deterioration of neurocognitive function and quality of life (QoL). As such, maintenance of QoL is an important treatment goal. This analysis presents time to deterioration (TtD) of QoL in patients with recurrent glioblastoma receiving Asunercept plus reirradiation (rRT) or rRT alone.

METHODS

Data from patients with a baseline and ≥ 1 post-baseline QoL assessment were included in this analysis. TtD was defined as the time from randomisation to the first deterioration in the EORTC QLQ-C15, PAL EORTC QLQ-BN20 and Medical Research Council (MRC)-Neurological status. Deterioration was defined as a decrease of ≥ 10 points from baseline in the QLQ-C15 PAL overall QoL and functioning scales, an increase of ≥ 10 points from baseline in the QLQ-C15 PAL fatigue scale and the QLQ-BN20 total sum of score, and a rating of "Worse" in the MRC-Neurological status. Patients without a deterioration were censored at the last QoL assessment. Kaplan-Meier estimates were used to describe TtD and treatment groups (Asunercept + rRT or rRT alone) were compared using the log-rank test.

RESULTS

Treatment with Asunercept + rRT was associated with significant improvement of TtD compared with rRT alone for QLQ-CL15 PAL overall QoL and physical functioning, and MRC Neurological Status (p ≤ 0.05). In the Asunercept + rRT group, QoL was maintained beyond progresison of disease (PoD).

CONCLUSION

Treatment with Asunercept plus rRT significantly prolongs TtD and maintains QoL versus rRT alone in recurrent glioblastoma patients.

Asunercept as an innovative therapeutic approach for recurrent glioblastoma and other malignancies

Glioblastoma is the most common and aggressive malignant tumor of the central nervous system. Despite the existing high unmet medical needs, the past few decades have seen no notable improvement in overall survival for glioblastoma patients. One active area of research to develop new therapeutic options for this disease is focusing on the CD95/Fas receptor and its ligand CD95L/FasL. It is now recognized that in addition to its role in programmed cell death, CD95/CD95L signaling is involved in a wide range of other apoptotic and non-apoptotic pathways directed toward T-effector cells and cells in the tumor microenvironment involved in tumor progression and invasiveness. Asunercept is a first-in-class recombinant glycosylated fusion protein, which has been designed to selectively bind to CD95L and therefore disrupt CD95/CD95L signaling. The current report provides a brief overview of the role of the CD95/CD95L signaling pathway in cancer pathogenesis and discusses how asunercept was designed to bind and neutralize CD95L and disrupt signaling thereby potentially improving outcomes in glioblastoma and other malignancies.

Apoptosis of tumor-infiltrating T lymphocytes: a new immune checkpoint mechanism

Immunotherapy based on checkpoint inhibitors is providing substantial clinical benefit, but only to a minority of cancer patients. The current priority is to understand why the majority of patients fail to respond. Besides T-cell dysfunction, T-cell apoptosis was reported in several recent studies as a relevant mechanism of tumoral immune resistance. Several death receptors (Fas, DR3, DR4, DR5, TNFR1) can trigger apoptosis when activated by their respective ligands. In this review, we discuss the immunomodulatory role of the main death receptors and how these are shaping the tumor microenvironment, with a focus on Fas and its ligand. Fas-mediated apoptosis of T cells has long been known as a mechanism allowing the contraction of T-cell responses to prevent immunopathology, a phenomenon known as activation-induced cell death, which is triggered by induction of Fas ligand (FasL) expression on T cells themselves and qualifies as an immune checkpoint mechanism. Recent evidence indicates that other cells in the tumor microenvironment can express FasL and trigger apoptosis of tumor-infiltrating lymphocytes (TIL), including endothelial cells and myeloid-derived suppressor cells. The resulting disappearance of TIL prevents anti-tumor immunity and may in fact contribute to the absence of TIL that is typical of "cold" tumors that fail to respond to immunotherapy. Interfering with the Fas-FasL pathway in the tumor microenvironment has the potential to increase the efficacy of cancer immunotherapy.

The TNF Family of Ligands and Receptors: Communication Modules in the Immune System and Beyond

The tumor necrosis factor (TNF) and TNF receptor (TNFR) superfamilies (TNFSF/TNFRSF) include 19 ligands and 29 receptors that play important roles in the modulation of cellular functions. The communication pathways mediated by TNFSF/TNFRSF are essential for numerous developmental, homeostatic, and stimulus-responsive processes in vivo. TNFSF/TNFRSF members regulate cellular differentiation, survival, and programmed death, but their most critical functions pertain to the immune system. Both innate and adaptive immune cells are controlled by TNFSF/TNFRSF members in a manner that is crucial for the coordination of various mechanisms driving either co-stimulation or co-inhibition of the immune response. Dysregulation of these same signaling pathways has been implicated in inflammatory and autoimmune diseases, highlighting the importance of their tight regulation. Investigation of the control of TNFSF/TNFRSF activities has led to the development of therapeutics with the potential to reduce chronic inflammation or promote anti-tumor immunity. The study of TNFSF/TNFRSF proteins has exploded over the last 30 yr, but there remains a need to better understand the fundamental mechanisms underlying the molecular pathways they mediate to design more effective anti-inflammatory and anti-cancer therapies.

Integrating in vitro experiments with in silico approaches for Glioblastoma invasion: the role of cell-to-cell adhesion heterogeneity

Glioblastoma cells adopt migration strategies to invade into the brain parenchyma ranging from individual to collective mechanisms, whose role and dynamics are not yet fully understood. In this work, we explore Glioblastoma heterogeneity and recapitulate its invasive patterns both in vitro, by utilizing primary cells along with the U87MG cell line, and in silico, by adopting discrete, individual cell-based mathematics. Glioblastoma cells are cultured three-dimensionally in an ECM-like substrate. The primary Glioblastoma spheroids adopt a novel cohesive pattern, mimicking perivascular invasion in the brain, while the U87MG adopt a typical, starburst invasive pattern under the same experimental setup. Mathematically, we focus on the role of the intrinsic heterogeneity with respect to cell-to-cell adhesion. Our proposed mathematical approach mimics the invasive morphologies observed in vitro and predicts the dynamics of tumour expansion. The role of the proliferation and migration is also explored showing that their effect on tumour morphology is different per cell type. The proposed model suggests that allowing cell-to-cell adhesive heterogeneity within the tumour population is sufficient for variable invasive morphologies to emerge which remain originally undetectable by conventional imaging, indicating that exploration in pathological samples is needed to improve our understanding and reveal potential patient-specific therapeutic targets.

Glioblastoma Treatments: An Account of Recent Industrial Developments

The different drugs and medical devices, which are commercialized or under industrial development for glioblastoma treatment, are reviewed. Their different modes of action are analyzed with a distinction being made between the effects of radiation, the targeting of specific parts of glioma cells, and immunotherapy. Most of them are still at a too early stage of development to firmly conclude about their efficacy. Optune, which triggers antitumor activity by blocking the mitosis of glioma cells under the application of an alternating electric field, seems to be the only recently developed therapy with some efficacy reported on a large number of GBM patients. The need for early GBM diagnosis is emphasized since it could enable the treatment of GBM tumors of small sizes, possibly easier to eradicate than larger tumors. Ways to improve clinical protocols by strengthening preclinical studies using of a broader range of different animal and tumor models are also underlined. Issues related with efficient drug delivery and crossing of blood brain barrier are discussed. Finally societal and economic aspects are described with a presentation of the orphan drug status that can accelerate the development of GBM therapies, patents protecting various GBM treatments, the different actors tackling GBM disease, the cost of GBM treatments, GBM market figures, and a financial analysis of the different companies involved in the development of GBM therapies.

Fas Versatile Signaling and Beyond: Pivotal Role of Tyrosine Phosphorylation in Context-Dependent Signaling and Diseases

The Fas/FasL system is known, first and foremost, as a potent apoptosis activator. While its proapoptotic features have been studied extensively, evidence that the Fas/FasL system can elicit non-death signals has also accumulated. These non-death signals can promote survival, proliferation, migration, and invasion of cells. The key molecular mechanism that determines the shift from cell death to non-death signals had remained unclear until the recent identification of the tyrosine phosphorylation in the death domain of Fas as the reversible signaling switch. In this review, we present the connection between the recent findings regarding the control of Fas multi-signals and the context-dependent signaling choices. This information can help explain variable roles of Fas signaling pathway in different pathologies.

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.