Discussion
This study illustrates the spectrum of AIR associated with anti-retinal antibodies after initiation of immunotherapy in patients with advanced cutaneous melanoma. In all three cases, visual symptoms developed after the initiation of immunotherapy with ipilimumab and nivolumab. The visual symptoms in two cases occurred within two weeks after initiation of immunotherapy (case 1 and 3) and one case (case 2) demonstrated insidious visual field deficits detected during the maintenance phase of immunotherapy. In our systematic review of published cases, the onset of visual symptoms was also highly variable, ranging from within a week to 2 years with a median of 7.5 weeks after the initiation of immunotherapy.
The presence of anti-retinal antibodies, coupled with the co-occurrence of well-documented irAEs such as endocrinopathy (cases 1 and 3),1 2 35 36 pulmonary sarcoidosis-like reaction and pneumonitis (case 2),37–40 suggests that the heightened immune response triggered by immunotherapy may have played an important role in the pathogenesis of AIR. Notably, all three patients were treated with both ipilimumab and nivolumab, which showed a higher rate of irAEs when used in combination.2 Without routine pretreatment serological screening, it is not possible to determine if these anti-retinal antibodies were already present at subclinical levels before initiation of immunotherapy or if the anti-retinal antibodies were generated as part of a wider autoimmune response triggered by immunotherapy. Indeed, a study by Duvoisin et al41 detected the presence of anti-TRPM1 autoantibodies in 5 out of 15 patients with advanced cutaneous melanoma without visual symptoms compared with weak positivity to these autoantibodies in 1 out of 50 controls without cancer, suggesting that patients with cutaneous melanoma may be more prone to developing anti-retinal antibodies, with or without visual symptoms, than the general population. However, the relevance of individual anti-retinal antibodies as markers of immunotherapy-induced AIR remains incompletely understood. Chen et al found the presence of anti-retinal antibodies against at least one retinal antigen in 13 out of 14 patients without AIR, although 10 of these patients had macular or optic nerve disease.42 Interestingly, none of these patients tested positive for anti-recoverin antibodies, suggesting that anti-recoverin antibodies may be possibly more specific to AIR. Given the high rate of positivity for anti-retinal antibodies even in patients without AIR, the presence of anti-retinal antibodies would need to be interpreted in the appropriate clinical context.
Despite some overlap in the specific anti-retinal antibodies detected between the three cases presented in this study, there is marked variation in the clinical presentation across the three cases. Case 1 may be considered a classic case of melanoma-associated retinopathy (MAR) given the characteristic negative b-wave on ERG in the absence of abnormal fundus findings, albeit with the development of visual symptoms soon after initiation of immunotherapy. In contrast, case 2 presented with profound visual field deficits associated with both anti-retinal and anti-optic nerve antibodies.43–48 The long delay in onset of visual symptoms after initiation of immunotherapy makes MAR unrelated to immunotherapy a possibility, although the patient’s visual symptoms and visual field deficits stabilised after immunotherapy cessation and immunosuppressive treatments. Case 3 is an example of acute exudative polymorphous vitelliform maculopathy (AEPVM), which is also termed acute exudative polymorphous paraneoplastic vitelliform maculopathy (AEPPVM) when found in the context of a malignancy.15 49–52 Paraneoplastic AEPVM or AEPPVM is characterized by the presence of antibodies against the retinal pigment epithelium (e.g. anti-bestrophin 1 or anti-peroxiredoxin 3 antibodies) in addition to a decreased Arden ratio on EOG, serous retinal detachments and vitelliform lesions resembling Best vitelliform macular dystrophy.15 49 51–57 Although AEPVM in Case 3 could be unrelated to immunotherapy, the timing of ocular symptoms and systemic irAEs after immunotherapy initiation support a causative role for immunotherapy. In our systematic review of published cases, there was a spectrum of retinal findings ranging from classic MAR, AEPVM, serous retinal detachment to birdshot-like chorioretinopathy after immunotherapy initiation.
Although it is difficult to make management recommendations based on the small number of cases included in this series, the occurrence of new visual symptoms after initiation of immunotherapy in patients should warrant a prompt ophthalmology evaluation due to the persistence of visual symptoms in a significant proportion of patients despite treatment. Two out of three patients in our case series did not have complete resolution of visual symptoms despite intravenous immunoglobin (IVIG) and systemic immunosuppressive treatments. The patient in case 1 had persistence of decreased dark adaptation despite treatment. Likewise, case 2 demonstrated no improvement in visual field loss following treatment. The patient in case 3 declined IVIG and had gradual resolution of subretinal fluid and visual symptoms over 20 months after treatment with periocular corticosteroid injections. Similarly, in our systematic review of published cases, only 5 out of 14 patients (10 out of 28 eyes) had complete resolution of visual symptoms. The most common visual symptoms reported in our cases series and systematic review were blurred vision, unspecified vision loss and photopsia. Nyctalopia, metamorphopsia, visual field deficits and photophobia were also reported. Notably, all patients had bilateral involvement.
The management of advanced cutaneous melanoma in these patients also merits discussion. Although the development of AIR is a relative contraindication to further continuation of immunotherapy, the decision to discontinue immunotherapy represents a therapeutic dilemma that must be balanced against prevention of systemic melanoma progression or recurrence. Only case 1 had a durable systemic response to immunotherapy even after its discontinuation, but she ultimately succumbed to complications associated with mononeuritis multiplex, an irAE. The remaining two cases had recurrence or progression of metastatic cutaneous melanoma following discontinuation of immunotherapy. Case 2 had recurrence at a single portacaval lymph node that was resected but otherwise remained melanoma-free. Case 3 had progression of systemic metastasis that required single-agent immunotherapy with no apparent recurrence of his AIR. Similarly, in 5 out of 14 published cases in which the systemic outcome was reported, 3 cases had progression of their underlying melanoma.
One of the limitations of this case series is the relatively small number of patients due to the rarity of the condition. However, some of our findings were mirrored in our systematic review of published cases. Furthermore, because patients do not routinely undergo serological testing for anti-retinal antibodies and/or evaluation by an ophthalmologist before starting immunotherapy, it cannot be established if these patients have pre-existing AIR that were exacerbated by immunotherapy or new-onset AIR induced by immunotherapy. It is possible that anti-retinal antibodies were present prior to initiation of immunotherapy but the retinopathy only became clinically evident after immunotherapy in these patients.
The limitations of our systematic review include the relatively small number of published cases and their heterogeneity, which limit the scope for an extensive meta-analysis. Furthermore, there is notable variability in clinical practice across the published cases such as the route of administration of corticosteroids. There is also variability in the reporting of variables and outcomes in these cases. For example, variables such as the presence or absence of systemic irAEs as well as systemic melanoma status on follow-up were frequently omitted.
A larger study could evaluate the role of screening patients for baseline anti-retinal antibodies prior to initiation of immunotherapy. Prospective screening of patients may better elucidate the natural history and the spectrum of AIR precipitated by immunotherapy. As the clinical utilisation of immunotherapy expands, there may be an increasing role for the utilisation of risk factors for irAEs which may impact the management of cutaneous melanoma.