Dabrafenib in patients with melanoma, untreated brain metastases, and other solid tumours: a phase 1 dose-escalation trial
ABSTRACT Dabrafenib is an inhibitor of BRAF kinase that is selective for mutant BRAF. We aimed to assess its safety and tolerability and to establish a recommended phase 2 dose in patients with incurable solid tumours, especially those with melanoma and untreated, asymptomatic brain metastases.
We undertook a phase 1 trial between May 27, 2009, and March 20, 2012, at eight study centres in Australia and the USA. Eligible patients had incurable solid tumours, were 18 years or older, and had adequate organ function. BRAF mutations were mandatory for inclusion later in the study because of an absence of activity in patients with wild-type BRAF. We used an accelerated dose titration method, with the first dose cohort receiving 12 mg dabrafenib daily in a 21-day cycle. Once doses had been established, we expanded the cohorts to include up to 20 patients. On the basis of initial data, we chose a recommended phase 2 dose. Efficacy at the recommended phase 2 dose was studied in patients with BRAF-mutant tumours, including those with non-Val600Glu mutations, in three cohorts: metastatic melanoma, melanoma with untreated brain metastases, and non-melanoma solid tumours. This study is registered with ClinicalTrials.gov, number NCT00880321.
We enrolled 184 patients, of whom 156 had metastatic melanoma. The most common treatment-related adverse events of grade 2 or worse were cutaneous squamous-cell carcinoma (20 patients, 11%), fatigue (14, 8%), and pyrexia (11, 6%). Dose reductions were necessary in 13 (7%) patients. No deaths or discontinuations resulted from adverse events, and 140 (76%) patients had no treatment-related adverse events worse than grade 2. Doses were increased to 300 mg twice daily, with no maximum tolerated dose recorded. On the basis of safety, pharmacokinetic, and response data, we selected a recommended phase 2 dose of 150 mg twice daily. At the recommended phase 2 dose in 36 patients with Val600 BRAF-mutant melanoma, responses were reported in 25 (69%, 95% CI 51·9-83·7) and confirmed responses in 18 (50%, 32·9-67·1). 21 (78%, 57·7-91·4) of 27 patients with Val600Glu BRAF-mutant melanoma responded and 15 (56%, 35·3-74·5) had a confirmed response. In Val600 BRAF-mutant melanoma, responses were durable, with 17 patients (47%) on treatment for more than 6 months. Responses were recorded in patients with non-Val600Glu BRAF mutations. In patients with melanoma and untreated brain metastases, nine of ten patients had reductions in size of brain lesions. In 28 patients with BRAF-mutant non-melanoma solid tumours, apparent antitumour activity was noted in a gastrointestinal stromal tumour, papillary thyroid cancers, non-small-cell lung cancer, ovarian cancer, and colorectal cancer.
Dabrafenib is safe in patients with solid tumours, and an active inhibitor of Val600-mutant BRAF with responses noted in patients with melanoma, brain metastases, and other solid tumours.
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ABSTRACT: The frequency of metastatic brain tumors has increased over recent years; the primary tumors most involved are breast cancer, lung cancer, melanoma and renal cell carcinoma. While radiation therapy and surgery remain the mainstay treatment in selected patients, new molecular drugs have been developed for brain metastases. Studies so far report interesting results. This review focuses on systemic cytotoxic drugs and, in particular, on new targeted therapies and their clinically relevant activities in brain metastases from solid tumors in adults.Cancer Treatment Reviews 05/2014; 40(8). DOI:10.1016/j.ctrv.2014.05.007 · 6.47 Impact Factor
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ABSTRACT: Despite a wealth of preclinical studies, it is unclear whether PIK3CA or phosphatase and tensin homolog (PTEN) gene aberrations are actionable in the clinical setting. Of 1,656 patients with advanced, refractory cancers tested for PIK3CA or PTEN abnormalities, PIK3CA mutations were found in 9% (146/1,589), and PTEN loss and/or mutation was found in 13% (149/1,157). In multicovariable analysis, treatment with a phosphatidylinositol 3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) inhibitor was the only independent factor predicting response to therapy in individuals harboring a PIK3CA or PTEN aberration. The rate of stable disease ≥6 months/partial response reached 45% in a subgroup of individuals with H1047R PIK3CA mutations. Aberrations in the PI3K/AKT/mTOR pathway are common and potentially actionable in patients with diverse advanced cancers. This work provides further important clinical validation for continued and accelerated use of biomarker-driven trials incorporating rational drug combinations.Cell Reports 01/2014; 6(2). DOI:10.1016/j.celrep.2013.12.035 · 7.21 Impact Factor
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ABSTRACT: Brain tumors are the most common solid pediatric malignancy. For high-grade, recurrent, or refractory pediatric brain tumors, radiation therapy (XRT) is an integral treatment modality. In the era of personalized cancer therapy, molecularly targeted agents have been designed to inhibit pathways critical to tumorigenesis. Our evolving knowledge of genetic aberrations in pediatric gliomas is being exploited with the use of specific targeted inhibitors. These agents are additionally being combined with XRT to increase the efficacy and duration of local control. In this review, we discuss novel agents targeting three different pathways in gliomas, and their potential combination with XRT. BRAF is a serine/threonine kinase in the RAS/RAF/MAPK kinase pathway, which is integral to cellular division, survival, and metabolism. Two-thirds of pilocytic astrocytomas, a low-grade pediatric glioma, contain a translocation within the BRAF gene called KIAA1549:BRAF that causes an overactivation of the MEK/MAPK signaling cascade. In vitro and in vivo data support the use of MEK or mammalian target of rapamycin (mTOR) inhibitors in low-grade gliomas expressing this translocation. Additionally, 15-20% of high-grade pediatric gliomas express BRAF V600E, an activating mutation of the BRAF gene. Pre-clinical in vivo and in vitro data in BRAF V600E gliomas demonstrate dramatic cooperation between XRT and small molecule inhibitors of BRAF V600E. Another major signaling cascade that plays a role in pediatric glioma pathogenesis is the PI3-kinase (PI3K)/mTOR pathway, known to be upregulated in the majority of high- and low-grade pediatric gliomas. Dual PI3K/mTOR inhibitors are in clinical trials for adult high-grade gliomas and are poised to enter studies of pediatric tumors. Finally, many brain tumors express potent stimulators of angiogenesis that render them refractory to treatment. An analog of thalidomide, CC-5103 increases the secretion of critical cytokines of the tumor microenvironment, including IL-2, IFN-γ, TNF-α, and IL-10, and is currently being evaluated in clinical trials for the treatment of recurrent or refractory pediatric central nervous system tumors. In summary, several targeted inhibitors with radiation are currently under investigation in both translational bench research and early clinical trials. This review article summarizes the molecular rationale for, and the pre-clinical data supporting the combinations of these targeted agents with other anti-cancer agents and XRT in pediatric gliomas. In many cases, parallels are drawn to molecular mechanisms and targeted inhibitors of adult gliomas. We additionally discuss the potential mechanisms underlying the efficacy of these agents.Frontiers in Oncology 05/2013; 3:110. DOI:10.3389/fonc.2013.00110