dabrafenib
Regulatory sources consulted
Approved indications
- Monotherapy only for unresectable or metastatic BRAF V600E melanoma. With trametinib: unresectable/metastatic or node-positive resected adjuvant BRAF V600E/K melanoma; metastatic BRAF V600E NSCLC; locally advanced or metastatic BRAF V600E anaplastic thyroid cancer without a satisfactory locoregional option; BRAF V600E solid tumors from age 1 without alternatives after progression, under accelerated approval; and low-grade glioma from age 1 requiring systemic treatment. Do not use in colorectal cancer or BRAF wild-type tumors.
Contraindications
Absolute
- CIMA: hypersensitivity to the active substance or excipients; the FDA label establishes no formal contraindications.
Clinical warnings
- With trametinib, monitor LVEF at baseline, at 1 month, and every 2–3 months. For severe fever, withhold both drugs, assess infection and renal function, hydrate and treat; consider corticosteroids if recurrent or prolonged. — OpenFDA, set_id fee1e6b1-e1a5-4254-9f2e-a70e0f8dbdea
- Monitor new RAS-associated malignancies, hemorrhage, uveitis, SCAR, hyperglycemia, and hemolysis in G6PD deficiency. Also consult the trametinib label when used together. — OpenFDA, set_id fee1e6b1-e1a5-4254-9f2e-a70e0f8dbdea
Drug interactions
- HighCYP3A4/CYP2C8 modulators and sensitive substrates
Mechanism: They may alter dabrafenib; dabrafenib induces enzymes and reduces exposure to many substrates, including hormonal contraceptives.
Recommendation: Avoid strong CYP3A4 or CYP2C8 inhibitors and strong inducers when possible; monitor toxicity if unavoidable. Dabrafenib induces CYP and may reduce sensitive substrates, including hormonal contraceptives; monitor INR with warfarin.
OpenFDA, set_id fee1e6b1-e1a5-4254-9f2e-a70e0f8dbdea
Adverse events
Common (≥1%)
pyrexia · rash · headache · arthralgia · nausea · fatigue
Pregnancy and lactation
Verify pregnancy. Women must use non-hormonal contraception during treatment and for 2 weeks afterward. Do not breastfeed during treatment or for 2 weeks afterward. It may impair male fertility.
Recent literature (PubMed)
Approximately 43 720 new cases of thyroid carcinoma are expected to be diagnosed in 2023 in the US. Five-year relative survival is approximately 98.5%. This review summarizes current evidence regarding pathophysiology, diagnosis, and management of early-stage and advanced thyroid cancer. Papillary thyroid cancer accounts for approximately 84% of all thyroid cancers. Papillary, follicular (≈4%), and oncocytic (≈2%) forms arise from thyroid follicular cells and are termed well-differentiated thyroid cancer. Aggressive forms of follicular cell-derived thyroid cancer are poorly differentiated thyroid cancer (≈5%) and anaplastic thyroid cancer (≈1%). Medullary thyroid cancer (≈4%) arises from parafollicular C cells. Most cases of well-differentiated thyroid cancer are asymptomatic and detected during physical examination or incidentally found on diagnostic imaging studies. For microcarcinomas (≤1 cm), observation without surgical resection can be considered. For tumors larger than 1 cm with or without lymph node metastases, surgery with or without radioactive iodine is curative in most cases. Surgical resection is the preferred approach for patients with recurrent locoregional disease. For metastatic disease, surgical resection or stereotactic body irradiation is favored over systemic therapy (eg, lenvatinib, dabrafenib). Antiangiogenic multikinase inhibitors (eg, sorafenib, lenvatinib, cabozantinib) are approved for thyroid cancer that does not respond to radioactive iodine, with response rates 12% to 65%. Targeted therapies such as dabrafenib and selpercatinib are directed to genetic mutations (BRAF, RET, NTRK, MEK) that give rise to thyroid cancer and are used in patients with advanced thyroid carcinoma. Approximately 44 000 new cases of thyroid cancer are diagnosed each year in the US, with a 5-year relative survival of 98.5%. Surgery is curative in most cases of well-differentiated thyroid cancer. Radioactive iodine treatment after surgery improves overall survival
Melanoma, the fifth most common cancer in the US, has increased from 8.8 per 100 000 in 1975 to 28.42 per 100 000 in 2022. Cutaneous melanoma comprises 94% of cases, with 104 960 US cases projected for 2025. Cutaneous melanoma presents as a new, changing, or irregularly pigmented skin lesion. Cutaneous melanoma subtypes include superficial spreading (≈70%), lentigo maligna (≈15%), nodular (≈5%), desmoplastic (≈4%), amelanotic (2%-8%), spitzoid (<2%), and acral (≈1%). Risk factors for cutaneous melanoma include UV radiation exposure, skin type (eg, skin that always burns, never tans), presence of benign and atypical nevi, and personal or family history of melanoma. Primary prevention consists of avoiding direct sunlight and indoor tanning, and photoprotection (sunscreen and sun-protective clothing). Based on United States Cancer Statistics data from 1999 to 2021, 77% of patients with cutaneous melanoma had localized disease (involving only the primary site), 9.5% had regional (nodal) disease, 4.7% had distant metastasis, and 8.8% were unstaged. Melanoma staging, which includes tumor thickness and ulceration and presence of lymph node or distant metastasis, ranges from stage 0 (melanoma in situ) to stage IV (distant metastasis). Localized melanoma (stage IA-IIA) is surgically excised, with margins of 0.5 cm to 2 cm based on depth of invasion. Sentinel lymph node biopsy is recommended for cutaneous melanoma that is ulcerated or 0.8 mm or more thick. Following surgery, patients with stage IIB-C melanoma have improved recurrence-free survival with adjuvant anti-PD-1 immunotherapy compared with placebo (hazard ratio [HR] for recurrence or death, 0.62 [95% CI, 0.49-0.79] for pembrolizumab and 0.42 [95% CI, 0.30-0.59] for nivolumab). For stage III disease, recurrence risk is decreased with nivolumab (HR, 0.72 [95% CI, 0.60-0.86]), pembrolizumab (HR, 0.61 [95% CI, 0.51-0.72]), or BRAF + MEK inhibitor therapy (dabrafenib + trametinib) (HR, 0.52 [95% CI, 0.43-0.63]). First-lin
In June 2022, the FDA granted Accelerated Approval to the BRAF inhibitor dabrafenib in combination with the MEK inhibitor trametinib for the treatment of adult and paediatric patients (≥6 years of age) with unresectable or metastatic BRAFV600E-mutant solid tumours, except for BRAFV600E-mutant colorectal cancers. The histology-agnostic approval of dabrafenib plus trametinib marks the culmination of two decades of research into the landscape of BRAF mutations in human cancers, the biochemical mechanisms underlying BRAF-mediated tumorigenesis, and the clinical development of selective RAF and MEK inhibitors. Although the majority of patients with BRAFV600E-mutant tumours derive clinical benefit from BRAF inhibitor-based combinations, resistance to treatment develops in most. In this Review, we describe the biochemical basis for oncogenic BRAF-induced activation of MAPK signalling and pan-cancer and lineage-specific mechanisms of intrinsic, adaptive and acquired resistance to BRAF inhibitors. We also discuss novel RAF inhibitors and drug combinations designed to delay the emergence of treatment resistance and/or expand the population of patients with BRAF-mutant cancers who benefit from molecularly targeted therapies.
Combination programmed cell death protein 1/cytotoxic T-cell lymphocyte-4-blockade and dual BRAF/MEK inhibition have each shown significant clinical benefit in patients with BRAFV600-mutant metastatic melanoma, leading to broad regulatory approval. Little prospective data exist to guide the choice of either initial therapy or treatment sequence in this population. This study was conducted to determine which initial treatment or treatment sequence produced the best efficacy. In a phase III trial, patients with treatment-naive BRAFV600-mutant metastatic melanoma were randomly assigned to receive either combination nivolumab/ipilimumab (arm A) or dabrafenib/trametinib (arm B) in step 1, and at disease progression were enrolled in step 2 to receive the alternate therapy, dabrafenib/trametinib (arm C) or nivolumab/ipilimumab (arm D). The primary end point was 2-year overall survival (OS). Secondary end points were 3-year OS, objective response rate, response duration, progression-free survival, crossover feasibility, and safety. A total of 265 patients were enrolled, with 73 going onto step 2 (27 in arm C and 46 in arm D). The study was stopped early by the independent Data Safety Monitoring Committee because of a clinically significant end point being achieved. The 2-year OS for those starting on arm A was 71.8% (95% CI, 62.5 to 79.1) and arm B 51.5% (95% CI, 41.7 to 60.4; log-rank P = .010). Step 1 progression-free survival favored arm A (P = .054). Objective response rates were arm A: 46.0%; arm B: 43.0%; arm C: 47.8%; and arm D: 29.6%. Median duration of response was not reached for arm A and 12.7 months for arm B (P < .001). Crossover occurred in 52% of patients with documented disease progression. Grade ≥ 3 toxicities occurred with similar frequency between arms, and regimen toxicity profiles were as anticipated. Combination nivolumab/ipilimumab followed by BRAF and MEK inhibitor therapy, if necessary, should be the preferred treatment sequence for a large majority
The 5-year results of this trial showed that adjuvant therapy with dabrafenib plus trametinib resulted in longer relapse-free survival and distant metastasis-free survival than placebo among patients with BRAF V600-mutated stage III melanoma. Longer-term data were needed, including data regarding overall survival. We randomly assigned 870 patients with resected stage III melanoma with BRAF V600 mutations to receive 12 months of dabrafenib (150 mg twice daily) plus trametinib (2 mg once daily) or two matched placebos. Here, we report the final results of this trial, including results for overall survival, melanoma-specific survival, relapse-free survival, and distant metastasis-free survival. The median duration of follow-up was 8.33 years for dabrafenib plus trametinib and 6.87 years for placebo. Kaplan-Meier estimates for overall survival favored dabrafenib plus trametinib over placebo, although the benefit was not significant (hazard ratio for death, 0.80; 95% confidence interval [CI], 0.62 to 1.01; P = 0.06 by stratified log-rank test). A consistent survival benefit was seen across several prespecified subgroups, including the 792 patients with melanoma with a BRAF V600E mutation (hazard ratio for death, 0.75; 95% CI, 0.58 to 0.96). Relapse-free survival favored dabrafenib plus trametinib over placebo (hazard ratio for relapse or death, 0.52; 95% CI, 0.43 to 0.63), as did distant metastasis-free survival (hazard ratio for distant metastasis or death, 0.56; 95% CI, 0.44 to 0.71). No new safety signals were reported, a finding consistent with previous trial reports. After nearly 10 years of follow-up, adjuvant therapy with dabrafenib plus trametinib was associated with better relapse-free survival and distant metastasis-free survival than placebo among patients with resected stage III melanoma. The analysis of overall survival showed that the risk of death was 20% lower with combination therapy than with placebo, but the benefit was not significant. Among patients