Choroidal involvement in Rosai-Dorfman disease successfully treated with cobimetinib

Outcomes After Treatment With Cobimetinib in Patients With Rosai-Dorfman Disease Based on KRAS and MEK Alteration Status

Importance

Rosai-Dorfman disease (RDD) is a rare histiocytic neoplasm with recent studies showing alterations in the MAPK pathway, most commonly in the KRAS and MEK genes in about 40% of patients. Reports on the use of MEK-inhibitor therapy in RDD have been limited to small case studies. There are no approved treatments for this neoplasm, and therefore patients with RDD need efficacious treatments.

Objective

To study the outcomes after treatment with cobimetinib based on MAPK pathway alterations in patients with RDD.

Design, Setting, and Participants

This retrospective cohort study conducted at 2 tertiary care centers included patients with RDD who underwent treatment with cobimetinib between January 1, 2013, and December 1, 2021. Cobimetinib was administered at a dosage of 20 to 60 mg orally once daily as a single agent for 21 days in a 28-day cycle. Pathology was centrally reviewed. Response assessment was centrally conducted and was based on the established positron emission radiography response criteria used for clinical trials of targeted therapies in histiocytosis.

Main Outcomes and Measures

Main outcomes were overall response rate (ORR), progression-free survival (PFS), adverse events (AEs) of cobimetinib in the entire cohort, and ORRs and PFS based on MAPK pathway alterations in patients with RDD.

Results

A total of 16 patients (median [range] age at cobimetinib initiation, 57 [31-74] years; 11 [69%] women) were included in the study. The median follow-up duration was 19.0 months (95% CI, 8.4-27.8 months). The ORR was 63% (n = 10), including 5 complete responses and 5 partial responses. Somatic alterations in the KRAS or MEK genes were detected in 8 (50%) patients. Patients with KRAS or MEK alterations had significantly higher ORR (88% vs 38%; P = .03), deeper responses (complete responses among responders: 71% vs 0%; P = .002), and better PFS (at 1 year, 100% vs 29% were free from progression or death, respectively; P < .001) compared with those without such alterations. Grade 2 or higher AEs occurred in 12 (75%) patients, and 9 (56%) required dose reduction or temporary/permanent treatment discontinuation due to AEs.

Conclusions and Relevance

In this cohort study, treatment with cobimetinib was associated with positive outcomes in KRAS- or MEK-variant RDD. However, AEs requiring dose modifications were common.

Regression of Intraocular Rosai- Dorfman Disease Following Treatment with Photodynamic Therapy

Rosai-Dorfman disease (RDD), a rare form of histiocytosis, has been reported to cause choroidal masses and subsequent serous retinal detachments. We present a case of RDD associated with a choroidal mass and retinal detachment that did not respond to corticosteroid treatment and regressed after treatment with photodynamic therapy (PDT). Following treatment, the patient had a successful anatomic and clinical outcome, with no recurrence of serous detachment and 20/25 visual acuity. This is the first report of choroidal RDD successfully treated with PDT. [Ophthalmic Surg Lasers Imaging Retina. 2021;52:568-571.].