Dataset Information


Targeting the cyclin dependent kinase and retinoblastoma axis overcomes standard of care resistance in BRAF V600E -mutant melanoma.

ABSTRACT: Patient-derived tumor xenograft (PDTX) mouse models were used to discover new therapies for naïve and drug resistant BRAFV600E -mutant melanoma. Tumor histology, oncogenic protein expression, and antitumor activity were comparable between patient and PDTX-matched models thereby validating PDTXs as predictive preclinical models of therapeutic response in patients. PDTX models responsive and non-responsive to BRAF/MEK standard of care (SOC) therapy were used to identify efficacious combination therapies. One such combination includes a CDK4/6 inhibitor that blocks cell cycle progression. The rationale for this is that the retinoblastoma protein (pRb) is 95% wildtype in BRAF mutant melanoma. We discovered that 77/77 stage IV metastatic melanoma tissues were positive for inactive phosphorylated pRb (pRb-Ser780). Rb is hyperphosphorylated and inactivated by CDK4/6:cyclin D1 and when restored to its hypophosphorylated active form blocks cell cycle progression. The addition of a CDK4/6 inhibitor to SOC therapy was superior to SOC. Importantly, triple therapy in an upfront treatment and salvage therapy setting provided sustained durable response. We also showed that CDK4/6 blockade resensitized drug resistant melanoma to SOC therapy. Durable response was associated with sustained suppression of pRb-Ser780. Thus, reactivation of pRb may prove to be a clinical biomarker of response and the mechanism responsible for durable response. In light of recent clinical trial data using this triple therapy against BRAFV600E -mutant melanoma, our findings demonstrating superior and prolonged durable response in PDTX models portend use of this therapeutic strategy against naïve and SOC resistant BRAFV600E -mutant metastatic melanoma coupled with pRB-Ser780 as a biomarker of response.


PROVIDER: S-EPMC5834273 | BioStudies | 2018-01-01

REPOSITORIES: biostudies

Similar Datasets

1000-01-01 | S-EPMC5392287 | BioStudies
2016-01-01 | S-EPMC5342782 | BioStudies
2016-01-01 | S-EPMC5095033 | BioStudies
| S-EPMC299840 | BioStudies
2019-01-01 | S-EPMC6792090 | BioStudies
1000-01-01 | S-EPMC6361951 | BioStudies
2018-01-01 | S-EPMC6171799 | BioStudies
2019-01-01 | S-EPMC6447953 | BioStudies
2013-01-01 | S-EPMC3786379 | BioStudies
2017-01-01 | S-EPMC5393973 | BioStudies