In patients with melanomas containing activating
BRAF
mutations, the combination of a BRAF inhibitor and a MEK inhibitor improved overall survival, as compared with a BRAF inhibitor alone, and was ...associated with many fewer second skin tumors.
The treatment of metastatic melanoma is rapidly evolving. The potent and specific BRAF inhibitors vemurafenib and dabrafenib, as compared with chemotherapy, have significantly improved response rates, along with progression-free and overall survival, in patients with metastatic melanoma with
BRAF
V600E or V600K mutations.
1
,
2
However, acquired resistance to BRAF inhibitors frequently develops through reactivation of the mitogen-activated protein kinase (MAPK) pathway, resulting in a median progression-free survival of 6 to 8 months.
2
–
5
In addition, the use of BRAF inhibitors may result in the development of secondary skin tumors, originating from a paradoxical activation of the MAPK pathway in cells . . .
The determination of individual cell trajectories through a high-dimensional cell-state space is an outstanding challenge for understanding biological changes ranging from cellular differentiation to ...epigenetic responses of diseased cells upon drugging. We integrate experiments and theory to determine the trajectories that single BRAF
mutant melanoma cancer cells take between drug-naive and drug-tolerant states. Although single-cell omics tools can yield snapshots of the cell-state landscape, the determination of individual cell trajectories through that space can be confounded by stochastic cell-state switching. We assayed for a panel of signaling, phenotypic, and metabolic regulators at points across 5 days of drug treatment to uncover a cell-state landscape with two paths connecting drug-naive and drug-tolerant states. The trajectory a given cell takes depends upon the drug-naive level of a lineage-restricted transcription factor. Each trajectory exhibits unique druggable susceptibilities, thus updating the paradigm of adaptive resistance development in an isogenic cell population.
Whole-exome sequencing was performed on four patients' tumors before exposure to pembrolizumab and after disease progression following a response to treatment. Acquired mutations involving antigen ...presentation and interferon response were noted.
Durable responses in metastatic cancers have been achieved with a variety of immunotherapies such as interleukin-2, adoptive cell transfer of tumor-infiltrating lymphocytes, antibodies that block cytotoxic T-lymphocyte–associated antigen 4 (CTLA4),
1
–
5
and antibodies that block programmed death 1 (PD-1).
6
–
10
However, in a recent study, approximately 25% of patients with melanoma who had had an objective response to PD-1 blockade therapy had disease progression at a median follow-up of 21 months.
11
The mechanisms of immune-resistant cancer progression are mostly unknown. Previous studies involving humans examined the loss of beta-2-microglobulin as a mechanism of acquired resistance to several forms of cancer . . .
PD-L1 and PD-L2 are ligands for the PD-1 immune inhibiting checkpoint that can be induced in tumors by interferon exposure, leading to immune evasion. This process is important for immunotherapy ...based on PD-1 blockade. We examined the specific molecules involved in interferon-induced signaling that regulates PD-L1 and PD-L2 expression in melanoma cells. These studies revealed that the interferon-gamma-JAK1/JAK2-STAT1/STAT2/STAT3-IRF1 axis primarily regulates PD-L1 expression, with IRF1 binding to its promoter. PD-L2 responded equally to interferon beta and gamma and is regulated through both IRF1 and STAT3, which bind to the PD-L2 promoter. Analysis of biopsy specimens from patients with melanoma confirmed interferon signature enrichment and upregulation of gene targets for STAT1/STAT2/STAT3 and IRF1 in anti-PD-1-responding tumors. Therefore, these studies map the signaling pathway of interferon-gamma-inducible PD-1 ligand expression.
Display omitted
•PD-L1 is primarily regulated by interferon gamma signaling in melanoma cells•PD-L2 is regulated by both interferon beta and gamma signaling•Regulation of PD-1 ligands works mainly through the JAK1/2-STAT1/3-IRF1 axis
Garcia-Diaz et al. performed a small hairpin RNA screen and genetic and functional studies to map the signaling pathways that result in reactive PD-L1 and PD-L2 on melanoma cells upon interferon gamma exposure. The authors highlight the importance of the JAK1/JAK2-STAT1/STAT2/STAT3-IRF1 axis for clinical responses to PD-1 blockade therapy.
'Immune checkpoint blockade' for cancer describes the use of therapeutic antibodies that disrupt negative immune regulatory checkpoints and unleash pre-existing antitumour immune responses. ...Antibodies targeting the checkpoint molecules cytotoxic T lymphocyte antigen 4 (CTLA4), programmed cell death 1 (PD1) and PD1 ligand 1 (PD-L1) have had early success in the clinic, which has led to approval by the US Food and Drug Administration of multiple agents in several cancer types. Yet, clinicians still have very limited tools to discriminate a priori patients who will and will not respond to treatment. This has fuelled a wave of research into the molecular mechanisms of tumour-intrinsic resistance to immune checkpoint blockade, leading to the rediscovery of biological processes critical to antitumour immunity, namely interferon signalling and antigen presentation. Other efforts have shed light on the immunological implications of canonical cancer signalling pathways, such as WNT-β-catenin signalling, cell cycle regulatory signalling, mitogen-activated protein kinase signalling and pathways activated by loss of the tumour suppressor phosphoinositide phosphatase PTEN. Here we review each of these molecular mechanisms of resistance and explore ongoing approaches to overcome resistance to immune checkpoint blockade and expand the spectrum of patients who can benefit from immune checkpoint blockade.
The rapidly advancing field of cancer immunotherapy is currently limited by the scarcity of noninvasive and quantitative technologies capable of monitoring the presence and abundance of CD8(+) T ...cells and other immune cell subsets. In this study, we describe the generation of (89)Zr-desferrioxamine-labeled anti-CD8 cys-diabody ((89)Zr-malDFO-169 cDb) for noninvasive immuno-PET tracking of endogenous CD8(+) T cells. We demonstrate that anti-CD8 immuno-PET is a sensitive tool for detecting changes in systemic and tumor-infiltrating CD8 expression in preclinical syngeneic tumor immunotherapy models including antigen-specific adoptive T-cell transfer, agonistic antibody therapy (anti-CD137/4-1BB), and checkpoint blockade antibody therapy (anti-PD-L1). The ability of anti-CD8 immuno-PET to provide whole body information regarding therapy-induced alterations of this dynamic T-cell population provides new opportunities to evaluate antitumor immune responses of immunotherapies currently being evaluated in the clinic.
Melanoma is one of the most common cancers in Western countries but has defied the trend of reductions in age-adjusted mortality observed in most other cancers in recent years. Biologically, melanoma ...is characterized by a high propensity to metastasize at low tumor volumes necessitating the need for effective drug therapies to support efforts in prevention and early detection for reducing mortality. Efforts to study the clinical biology of melanoma have led to a new understanding of the disease, with genomic studies identifying several targetable oncogenes, in particular the protein kinases BRAF and KIT. Biologic studies have also identified a variety of immunologic targets, including the programmed death 1 (PD-1) and cytotoxic T-cell lymphocyte-associated antigen 4 (CTLA-4) inhibitory molecules expressed on T lymphocytes. After several decades of clinical trials that failed to demonstrate improvement in overall survival in patients with advanced melanoma, small molecule inhibitors of BRAF or MEK and inhibition of CTLA-4 can improve survival in patients with advanced disease. These early clinical studies have provided a great opportunity to improve mortality in melanoma with the significant potential of combinations of signaling inhibitors or signaling inhibitors combined with immunologic agents, particularly when used in the adjuvant setting, and to transform the care of patients with this most challenging of cancers.
Through a gain-of-function kinome screen,
was identified as a mediator of resistance to T-cell immunotherapy not previously identified using CRISPR-based screens. MEX3B is a posttranscriptional ...regulator of HLA-A, validating the critical role of tumor-intrinsic antigen presentation in T-cell immunotherapy and indicating a new putative molecular target.
.
Interleukin-2 (IL-2) is a component of most protocols of adoptive cell transfer (ACT) therapy for cancer, but is limited by short exposure and high toxicities. NKTR-214 is a kinetically-engineered ...IL-2 receptor βγ (IL-2Rβγ)-biased agonist consisting of IL-2 conjugated to multiple releasable polyethylene glycol chains resulting in sustained signaling through IL-2Rβγ. We report that ACT supported by NKTR-214 increases the proliferation, homing and persistence of anti-tumor T cells compared to ACT with IL-2, resulting in superior antitumor activity in a B16-F10 murine melanoma model. The use of NKTR-214 increases the number of polyfunctional T cells in murine spleens and tumors compared to IL-2, and enhances the polyfunctionality of T and NK cells in the peripheral blood of patients receiving NKTR-214 in a phase 1 trial. In conclusion, NKTR-214 may have the potential to improve the antitumor activity of ACT in humans through increased in vivo expansion and polyfunctionality of the adoptively transferred T cells.
PDF
