Inclusion Criteria:

1. Male and female participants aged ≥18 years.
2. Participants with choroidal and ciliary body [P13.1] tumours.
3. Participants with primary localized UM requiring enucleation (Cohort 1) or plaque brachytherapy at high risk of vision loss (Cohort 2), as per investigator assessment.
4. Participants with ECOG performance status 0-1.
5. Tumour thickness > 4 mm.
6. Females of child bearing potential must have a negative urine pregnancy test result at screening.

Exclusion Criteria:

1. Participant has received previous treatment with a PKC inhibitor at any time.
2. Participant has received a prior diagnosis of metastatic disease.
3. Presence of a tumour originating from the iris.
4. Presence of intractable untreatable raised intraocular pressure.
5. Presence of ring melanoma.
6. Presence of severe glaucoma or uveitis.
7. Participant is under active treatment for any other macular condition.

9. Female participants who are pregnant or lactating. 10. Participant is unable to follow protocol requirements.