Fig. 1

Bilateral serous retinopathy (left eye shown) in a 64-year-old woman receiving cobimetinib combined with vemurafenib. At baseline, ophthalmic examination findings were normal, and no retinal abnormalities were detected either on bidimensional near-infrared image of the macula or on cross-sectional optical coherence tomography scan across the fovea (first row). On study day 8, the patient had nonserious grade 2 bilateral blurred vision. On study day 10, ocular examination with indirect ophthalmoscopy revealed bilateral serous subfoveal neurosensory detachment (i.e. subretinal fluid). Retinal imaging showed that detachments of the neurosensory retina were not limited to the fovea but were multiple and extended across the macular area (second and third rows, white arrows). A diagnosis of nonserious grade 2 serous retinopathy was made, and no treatment was administered for this event. On study day 14, the event of neurosensory detachments was considered resolved on indirect ophthalmoscopy, and blurred vision was considered resolved on study day 15. On study day 21, retinal imaging confirmed resolution of the retinal abnormalities (fourth row). The investigator considered blurred vision and serous retinopathy to be related to cobimetinib combined with vemurafenib. Treatment with cobimetinib combined with vemurafenib was permanently discontinued on study day 36 because of other adverse events, including pyrexia, rash, and elevated liver enzyme levels, with consideration of the previous event of serous retinopathy