FDA Grants OPN-6602 Orphan Drug Status in R/R Myeloma

• The FDA granted orphan drug designation (ODD) to OPN-6602 for the treatment of patients with relapsed/refractory (R/R) multiple myeloma.
• OPN-6602 is an oral small molecule inhibitor of the E1A binding protein (EP300) and CREB-binding protein (CBP).
• A phase 1 trial (NCT06433947) is currently evaluating OPN-6602 in patients with multiple myeloma.

The FDA has granted orphan drug designation (ODD) to OPN-6602 for the treatment of patients with R/R multiple myeloma.¹

OPN-6602 is an oral small-molecule inhibitor targeting EP300 and CBP, key transcriptional regulators in multiple myeloma pathophysiology.¹ Preclinical studies of the agent have demonstrated OPN-6602’s antitumor activity.

Data presented at the 2024 American Society of Hematology Annual Meeting showed that OPN-6602 as monotherapy led to tumor suppression in 71% of models. Notably, when combined with mezigdomide, pomalidomide (Pomalyst), and dexamethasone, tumor regression was observed in 100% of models, with a sustained duration of response.

OPN-6602 is now being evaluated in a phase 1 trial for patients with R/R multiple myeloma with patient enrollment ongoing at multiple sites across the US.

Microscopic photorealistic image of myeloma cells - Generated with Google Gemini AI

“We are pleased to have received ODD for OPN-6602 for the treatment of multiple myeloma, a further validation of the drug’s therapeutic potential in patients with this disease who have limited treatment options once they have relapsed,” said Gideon Bollag, PhD, chief scientific officer of Opna Bio, in a press release.

In the open-label, phase 1 study, experts are assessing the safety, tolerability, pharmacokinetics, and pharmacodynamics of OPN-6602 in patients with R/R multiple myeloma.² The trial comprises 3 cohorts:

1. Dose-escalation monotherapy arm
2. Dose-escalation arm combining OPN-6602 with dexamethasone
3. Dose-expansion cohort

In the combination arm, patients are receiving OPN-6602 daily with dexamethasone at a dose of 40 mg administered on days 1, 8, and 15 of each cycle.

Eligible patients must have relapsed or refractory multiple myeloma with disease progression after at least 3 prior therapies, including an immunomodulatory agent, proteasome inhibitor, and anti-CD38 antibody. Patients must also have adequate organ function and intolerance or ineligibility for established treatments known to provide clinical benefit.

The primary end points of the study are the number and type of dose-limiting toxicities, treatment-emergent adverse events, and clinical laboratory test abnormalities.

REFERENCES

1. Opna Bio receives orphan drug designation for OPN-6602, an oral EP300/CBP bromodomain inhibitor, for multiple myeloma. News release. Opna Bio. February 12, 2025. Accessed February 17, 2025. https://tinyurl.com/3pacjyaj

2. Study to assess safety and tolerability of OPN-6602 in subjects with relapsed and/or refractory multiple myeloma. ClinicalTrials.gov. Updated December 10, 2024. Accessed February 17, 2025. https://clinicaltrials.gov/study/NCT06433947