A phase 2 safety and efficacy study of neoadjuvant/adjuvant darovasertib for localized ocular melanoma.
Authors: Joshua Anthony M. , O'day Roderick , Glasson William , Sia David , McGrath Lindsay , Ameratunga Malaka , Cosman Rasha , Cherepanoff Svetlana , O'Quigley Michael , Beaupre Darrin M. , Conway Max , Lim Li-Anne , McKenzie John , McKay Daniel , Shackleton Mark J. , Fung Adrian , Isaacs Timothy , Yousif Jacob , Brooks Christine , Psaroulis Trifon 
Published: August 2024

9510 Background: Darovasertib is a protein kinase C (PKC) inhibitor with meaningful activity in metastatic uveal melanoma (UM) due to its effect on PKC delta downstream of canonical GNAQ/GNA11 mutations. To date, its clinical activity in patients with localized primary disease has not been assessed in either neoadjuvant or adjuvant settings. Methods: Patients planned for enucleation with localized UM were treated in an initial safety cohort with darovasertib 300mg BID for 1 month (n=3 patients), and then following DSMB agreement in an expansion cohort for up to 6 months (n=12 patients) as neoadjuvant treatment prior to definitive management (enucleation, plaque brachytherapy or EBRT) across 3 Australian centers. All patients were eligible to receive up to 6 months of adjuvant treatment with darovasertib at investigator discretion after definitive management of their primary tumour. Tumour volume was calculated by the rotational ellipsoid method. Results: 15 patients (male n=7, female n=8; median age 62 years (range, 33-76 years)) were enrolled. At baseline, AJCC tumor stages were T3a (n=5), T3b (n=4), T4a (n=4), T4b (n=2), and the median tumor size (maximum thickness/diameter/volume) was 9.7mm/ 15.6 mm/ 2463 mm3. At datalock; 11/15 patients had completed primary treatment, 4/15 remained on neoadjuvant treatment, 6 patients received adjuvant darovasertib after primary treatment of their UM with 3 patients completing the planned 6-months . Median tumor shrinkage (maximum height/base/volume change) was 11.2%/ 7.6%/ 22.7% after 1 month of treatment and 31.7%/ 11.9% /45.3% after 6 months. At datalock, 6/9 (66%) currently completed neoadjuvant patients were converted to plaque brachytherapy (n=5) or EBRT (n=1) with 3 ongoing. One patient with high-risk cytogenetic features had relapsed with metastatic disease despite receiving 6-months of neoadjuvant darovasertib and another 6-months of adjuvant treatment. Treatment emergent adverse events included postural hypotension (Gr1/2 – 13/13%), syncope (Gr3 – 13%), rash (Gr1/2 – 33/5%), pruritis (Grr1 – 13%), dizziness (Gr1 – 27%), fatigue (Gr1/2 – 30/5%), nausea (Gr1/2 – 73/6%), vomiting (Gr1 – 40%), and diarrhea (Gr1 – 60%). Updated results, histopathological and genomic outcomes will be presented. Conclusions: NADOM provides the first evidence that a globe-salvage neoadjuvant treatment strategy in UM is feasible, safe, and efficacious. The results suggest that PKC inhibition with darovasertib can induce clinically meaningful tumor shrinkage in patients with primary UM patients who otherwise require enucleation. Larger trials are in now progress (NCT05907954) to further quantify visual and oncological outcomes. Clinical trial information: 05187884.