Ophthalmologic Monitoring and Management for RAF/MEK Pathway Inhibitors

Here is a comprehensive overview of recommended ophthalmologic monitoring protocols and management strategies for patients on RAF/MEK pathway inhibitors, applicable to tovorafenib and its drug class.

A baseline ophthalmologic examination is recommended before initiating MEK or RAF inhibitor therapy, though there is currently no formal FDA mandate for routine screening in all patients.¹⁾ This baseline evaluation serves to differentiate preexisting pathology from treatment-emergent MEK inhibitor-associated retinopathy (MEKAR) and should include:

• Best-corrected visual acuity (BCVA)*
• Dilated fundus examination*
• Optical coherence tomography (OCT) — the most sensitive tool for detecting subclinical subretinal fluid²⁾³⁾*
• Color vision testing and visual field assessment as clinically indicated⁴⁾*

The NCCN Guidelines for Histiocytic Neoplasms specifically recommend that monitoring by retinal exam with OCT is recommended for patients on MEK inhibitors.⁵⁾ A real-world study of MEK inhibitor use in histiocytic neoplasms found that baseline retinal exams were performed in only 49.4% of patients, highlighting a gap in practice.⁶⁾

• Assess for visual symptoms at each visit — the binimetinib (Mektovi) FDA label explicitly requires this.⁷⁾*
• Perform ophthalmologic examination at regular intervals, for new or worsening visual disturbances, and to follow new or persistent ophthalmologic findings.*
• In clinical trials of binimetinib, patients were monitored with OCT biweekly for the first 2 months, then monthly thereafter. This represents a reasonable protocol for higher-risk patients.*
• Regular ophthalmologic examination is particularly appropriate for patients at increased risk, including those with a history of ocular inflammation, infection, or underlying macular/retinal disease.*

Understanding the typical timeline helps guide monitoring intensity:

• Median time to onset of serous retinopathy with cobimetinib: 15 days (range 7–111 days)⁸⁾*
• Median time to subretinal fluid detection by OCT: 14 days, with 80% of patients showing abnormal OCT findings within the first 28-day cycle⁹⁾*
• Median time to onset with binimetinib: 1.2 months (range 0–17.5 months)*

• Most cases are mild, self-limited, and reversible — 48% of cobimetinib-associated serous retinopathy cases resolved without any dose modification.*
• For retinal pigment epithelial detachment (RPED): the trametinib FDA label recommends withholding the drug for up to 3 weeks. If improved, resume at the same or lower dose. If not improved, permanently discontinue or resume at a lower dose.¹⁰⁾*
• In pediatric patients, MEKAR resolved within 1–2 weeks of drug discontinuation, and OCT confirmed complete resolution.*
• Importantly, cessation of life-extending MEK inhibitor therapy is not indicated when subretinal fluid is present without significant visual impairment.*

• This is a rare but serious event requiring permanent discontinuation of the MEK inhibitor (per the trametinib FDA label).*

• Typically managed with dose reduction of the BRAF inhibitor and topical corticosteroids. Uveitis generally resolves completely upon drug discontinuation.*

Based on the trametinib FDA label:

• Multidisciplinary communication between oncology and ophthalmology is essential — ocular adverse events are often associated with other systemic adverse effects that may independently require dose modification.¹¹⁾*
• Long-term MEK inhibitor use may cause retinal thinning that, while currently without functional relevance, warrants continued monitoring even after initial retinopathy resolves.¹²⁾*
• Patients should be counseled to report any new visual symptoms (blurred vision, color vision changes, photopsia, visual field defects) promptly, as early detection allows for timely intervention and typically full reversibility.*

1. Jeng-Miller KW, Miller MA, Heier JS. Ocular Effects of MEK Inhibitor Therapy: Literature Review, Clinical Presentation, and Best Practices for Mitigation. The Oncologist. 2024;29(5):e616-e621. DOI
2. Francis JH, Habib LA, Abramson DH, et al. Clinical and Morphologic Characteristics of MEK Inhibitor-Associated Retinopathy: Differences From Central Serous Chorioretinopathy. Ophthalmology. 2017;124(12):1788-1798. DOI
3. Weber ML, Liang MC, Flaherty KT, Heier JS. Subretinal Fluid Associated With MEK Inhibitor Use in the Treatment of Systemic Cancer. JAMA Ophthalmology. 2016;134(8):855-62. DOI
4. Urner-Bloch U, Urner M, Stieger P, et al. Transient MEK Inhibitor-Associated Retinopathy in Metastatic Melanoma. Ann Oncol. 2014;25(7):1437-1441. DOI
5. Histiocytic Neoplasms. National Comprehensive Cancer Network. Updated 2026-05-08.
6. Abstracts From the 41st Annual Meeting of the Histiocyte Society. Pediatr Blood Cancer. 2025;72 Suppl 5:e70014. DOI
7. Food and Drug Administration. MEKTOVI (binimetinib) prescribing information. 2025. FDA Label*
8. Barteselli G, Goodman GR, Patel Y, et al. Characterization of Serous Retinopathy Associated With Cobimetinib: Integrated Safety Analysis of Four Studies. Drug Saf. 2022;45(12):1491-1499. DOI
9. Sever A, Dotan G, Brik D, et al. Ocular Safety and Visual Acuity Stability in Pediatric Patients With Optic Pathway Gliomas and Orbital Plexiform Neurofibromas Treated With BRAF and MEK Inhibitors. Pediatr Blood Cancer. 2025;72(7):e31709. DOI
10. Food and Drug Administration. Mekinist (trametinib) prescribing information. 2026. FDA Label*
11. Mettler C, Monnet D, Kramkimel N, et al. Ocular Safety Profile of BRAF and MEK Inhibitors: Data From the World Health Organization Pharmacovigilance Database. Ophthalmology. 2021;128(12):1748-1755. DOI
12. Méndez-Martínez S, Calvo P, Ruiz-Moreno O, et al. Ocular Adverse Events Associated With MEK Inhibitors. Retina. 2019;39(8):1435-1450. DOI
13. Urner-Bloch U, Urner M, Jaberg-Bentele N, et al. MEK Inhibitor-Associated Retinopathy (MEKAR) in Metastatic Melanoma: Long-Term Ophthalmic Effects. Eur J Cancer. 2016;65:130-8. DOI