Low-dose vemurafenib monotherapy in BRAFV600E -mutated Erdheim-Chester disease.
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ABSTRACT:
SUBMITTER: Ruan GJ
PROVIDER: S-EPMC8023000 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:BackgroundErdheim-Chester disease (ECD), a rare inflammatory myeloid neoplasm, is known to be fundamentally reliant on the constitutive activation of the MAPK signaling pathway in the majority of patients. Consequently, inhibition of the V600E-mutant BRAF kinase has proven to be a safe and efficacious long-term therapeutic strategy for BRAF-mutant ECD patients. Nevertheless, in a subset of patients with CNS disease, the efficacy of long-term treatment may diminish, facilitating suboptimal responses or disease progression.MethodsWe retrospectively describe 3 BRAF-mutant ECD patients whose treatment with Vemurafenib was upgraded to Vemurafenib/Cobimetinib due to either disease progression, insufficient response, or unacceptable toxicity. CNS response to therapy was evaluated using magnetic resonance imaging (MRI) and extra-cranial disease was monitored using 18F-fludeoxyglucose positron emission tomography/computed tomography (PET/CT).ResultsThree patients with a mean age of 52.6 years were treated with Vemurafenib for a mean duration of 26.6 months (range: 6-52). Monotherapies were upgraded to Vemurafenib/Cobimetinib dual therapy. The combination therapy was administered for a mean duration of 21 months (range: 19-23). All patients exhibited clinical and neurological improvement. Regression of lesions on MRI was noted in 2 patients. Both patients characterized by a PET-avid disease responded to the biological treatment regimen with complete metabolic remissions.ConclusionDual inhibition of BRAF and downstream MEK may be a safe and effective therapeutic strategy for BRAF-mutant ECD patients for whom BRAF inhibitor therapy proved insufficient and as such appropriate for the long-term management of CNS disease in ECD.
| S-EPMC7212923 | biostudies-literature
Project description:BackgroundAnaplastic thyroid cancer (ATC) is one of the most aggressive malignancies, representing less than 5% of all thyroid carcinomas. Τhe median survival is limited to months due to the resistance of ATC to surgery, radioiodine therapy, radiotherapy and chemotherapy. This review will cover novel agents involving several cellular signaling pathways including the BRAF pathway. The BRAF inhibitor vemurafenib improves survival among patients with metastatic melanoma, hairy-cell leukemia and intracranial neoplasms with BRAF gene mutations. The frequency of a BRAF (V600E) mutation in ATC is about 25%.Case presentationWe report the first case of a marked partial response to adjuvant first line monotherapy with vemurafenib in BRAF V600E-mutated ATC. The 78-year-old man showed a sustained response for 7 months, thereafter scans revealed progressive disease and the patient died 10 months after first diagnosis. This case report is accompanied by a comprehensive review of current strategies and tools for ATC treatment.ConclusionsThis case and the review of current data confirm the benefit of BRAF inhibition in BRAF-mutated ATC, limited by acquired resistance to targeted therapy.
| S-EPMC9976495 | biostudies-literature
Project description:Hairy cell leukemia (HCL) is a chronic B-cell lymphoproliferative disorder that accounts for 2% of all leukemia. Recent identification of the recurrent V600E BRAF mutation in a majority of HCL patients has led some teams to evaluate the clinical potential of vemurafenib, a BRAF V600 specific inhibitor in a limited number of refractory HCL patients. Recently, we published the case of an HCL patient successfully treated with a low dose of vemurafenib. Eight months after the ending of treatment this patient relapsed. We present here the successful retreatment of this patient with a second line of vemurafenib. Our data suggest for the first time that vemurafenib at the dose of 240 mg once a day could be sufficient to maintain a complete hematological remission after an initial induction treatment with low-dose vemurafenib (2 × 240 mg) daily without inducing major toxicity.
| S-EPMC4341463 | biostudies-literature
Project description:To optimally integrate targeted kinase inhibitors and immunotherapies in the treatment of melanoma, it will be critical to understand how BRAFV600E mutational status and BRAFV600E inhibition influence the expression of genes that govern antitumor immune responses. Because major histocompatibility complex (MHC) molecules are critical for interactions between tumor cells and lymphocytes, we investigated the impact of BRAFV600E-selective inhibitors on the expression of MHC molecules. We found that the treatment of A375 melanoma cells with vemurafenib enhances the induction of MHC Class I and Class II molecules by interferon γ and IFNα2b. Consistent with these findings, we observed that the forced overexpression of BRAFV600E has the opposite effect and can repress the baseline expression of MHC Class I molecules in A375 cells. Further studies utilizing eight other melanoma cell lines revealed that the vemurafenib-mediated enhancement of MHC induction by IFNγ only occurs in the context of homozygous, but not heterozygous, BRAFV600E mutation. These findings suggest that BRAFV600E activity directly influences the expression of MHC molecules and the response to Type I and Type II IFNs. Furthermore, our data suggest that the effect of vemurafenib on the expression of immune system-relevant genes may depend on the zygosity of the BRAFV600E mutation, which is not routinely assessed in melanoma patients.
| S-EPMC3583938 | biostudies-literature
Project description:The BRAF kinase, within the mitogen activated protein kinase (MAPK) signaling pathway, harbors activating mutations in about half of melanomas and to a significant extent in many other cancers. A single valine to glutamic acid substitution at residue 600 (BRAFV600E) accounts for about 90% of these activating mutations. While BRAFV600E-selective small molecule inhibitors, such as debrafenib and vemurafenib, have shown therapeutic benefit, almost all patients develop resistance. Resistance often arises through reactivation of the MAPK pathway, typically through mutation of upstream RAS, downstream MEK, or splicing variants. RAF kinases signal as homo- and heterodimers, and another complication associated with small molecule BRAFV600E inhibition is drug-induced allosteric activation of a wild-type RAF subunit (BRAF or CRAF) of the kinase dimer, a process called "transactivation" or "paradoxical activation." Here, we used BRAFV600E and vemurafenib as a model system to develop chemically linked kinase inhibitors to lock RAF dimers in an inactive conformation that cannot undergo transactivation. This structure-based design effort resulted in the development of Vem-BisAmide-2, a compound containing two vemurafenib molecules connected by a bis amide linker. We show that Vem-BisAmide-2 has comparable inhibitory potency as vemurafenib to BRAFV600E both in vitro and in cells but promotes an inactive dimeric BRAFV600E conformation unable to undergo transactivation. The crystal structure of a BRAFV600E/Vem-BisAmide-2 complex and associated biochemical studies reveal the molecular basis for how Vem-BisAmide-2 mediates selectivity for an inactive over an active dimeric BRAFV600E conformation. These studies have implications for targeting BRAFV600E/RAF heterodimers and other kinase dimers for therapy.
| S-EPMC5108658 | biostudies-literature
Project description: Not available
| S-EPMC8355474 | biostudies-literature
Project description:PurposeWe report a patient with severe multi-organ dysfunction of unknown origin who presented with bilateral orbital and chorioretinal manifestations that led to the diagnosis of Erdheim-Chester Disease (ECD).ObservationsECD is a rare, histiocytic, proliferative disorder characterized by multi-systemic organ involvement that has historically lacked effective therapy. Our patient underwent genetic testing that was positive for the BRAF V600E mutation; therefore, the patient was treated with vemurafenib.Conclusions and importanceThis case demonstrates the rare orbital and intraocular manifestations of ECD and the unfortunate impact of a delayed diagnosis, the importance of early gene therapy testing for management decisions, and the utilization of targeted directed therapy to improve visual outcomes and quality of life.
| S-EPMC6076364 | biostudies-literature
Project description:BRAF mutation testing to determine eligibility for treatment with vemurafenib was performed on archival skin lesions of a 54-year-old patient diagnosed with Erdheim-Chester disease (ECD) in 1999. Sanger sequencing of DNA extracted from a 2008 skin lesion identified two non-contiguous base substitutions in BRAF, which were shown by next-generation sequencing (NGS) to be located in the same allele. Due to its long-standing duration, molecular evolution of disease was possible; however, both Sanger and NGS of a 2000 skin lesion were unsuccessful due to the poor quality of DNA. Finally, droplet digital PCR using a probe specific for this novel mutation detected the complex BRAF mutation in both the 2000 and 2008 lesions, indicating this case to be ECD with a novel underlying BRAF p.Thr599_Val600delinsArgGlu mutation. Although well at present, molecular modelling of the mutant BRAF suggests suboptimal binding of vemurafenib and hence reduced therapeutic effectiveness.
| S-EPMC5534755 | biostudies-literature
Project description:BRAFV600 -mutated melanoma brain metastases (MBMs) are responsive to BRAF inhibitors, but responses are generally less durable than those of extracranial metastases. We tested the hypothesis that the drug efflux transporters P-glycoprotein (P-gp; ABCB1) and breast cancer resistance protein (BCRP; ABCG2) expressed at the blood-brain barrier (BBB) offer MBMs protection from therapy. We intracranially implanted A375 melanoma cells in wild-type (WT) and Abcb1a/b;Abcg2-/- mice, characterized the tumor BBB, analyzed drug levels in plasma and brain lesions after oral vemurafenib administration, and determined the efficacy against brain metastases and subcutaneous lesions. Although contrast-enhanced MRI demonstrated that the integrity of the BBB is disrupted in A375 MBMs, vemurafenib achieved greater antitumor efficacy against MBMs in Abcb1a/b;Abcg2-/- mice compared with WT mice. Concordantly, P-gp and BCRP are expressed in MBM-associated brain endothelium both in patients and in A375 xenografts and expression of these transporters limited vemurafenib penetration into A375 MBMs. Although initially responsive, A375 MBMs rapidly developed therapy resistance, even in Abcb1a/b;Abcg2-/- mice, and this was unrelated to pharmacokinetic or target inhibition issues. Taken together, we demonstrate that both intrinsic and acquired resistance can play a role in MBMs.
| S-EPMC10761933 | biostudies-literature
Project description:Background: The BRAFV600E mutation is the most common driver mutation in papillary thyroid cancer (PTC) and anaplastic thyroid cancer (ATC). This mutation is considered actionable and, for BRAFV600E-mutated ATC, a BRAF inhibitor (dabrafenib) in combination with an MEK inhibitor (trametinib) is FDA approved. BRAF inhibitors have also shown efficacy in BRAFV600E-mutated PTC. However, as with all targeted therapies, resistance to these drugs eventually develops. It is essential that we understand the mechanisms of resistance to the BRAF inhibitors in thyroid cancer to develop future strategies to effectively treat these patients and improve survival. Patients: Herein, we describe four patients with thyroid cancer treated with selective BRAF inhibitors, who developed a RAS mutation in addition to the BRAFV600E mutation at progression. Results: Patients 1 and 3 acquired a KRASG12V mutation in the progressive tumor, patient 2 acquired a NRASQ61K mutation in a progressive lymph node, and patient 4 acquired NRASG13D mutation on liquid biopsy performed at the time of radiographic disease progression. Conclusion: Similar to the melanoma experience, the emergence of RAS mutations appears to act as a mechanism of resistance to BRAF inhibitors in thyroid cancers.
| S-EPMC7869871 | biostudies-literature