The US Food and Drug Administration (FDA) has put a partial clinical hold on all clinical trials of biotech company Oncopeptides’ multiple myeloma drug candidate, melflufen (melphalan flufenamide).
The agency’s decision is based on data from the global, randomised, open-label, head-to-head Phase III OCEAN clinical trial of melflufen plus dexamethasone in relapsed refractory multiple myeloma.
Melflufen is a peptide-drug conjugate that acts on aminopeptidases and quickly produces alkylating agents within cancer cells. Targeting aminopeptidases is expected to have a specific activity in cancer cells while avoiding healthy cells.
Overexpressed in multiple myeloma cells, aminopeptidases are linked to advanced disease.
During the OCEAN trial, the investigational combination was compared to pomalidomide plus dexamethasone in patients who previously received two to four treatments.
Launched in 2017, the trial enrolled 495 subjects at more than 100 hospitals across 21 countries worldwide. Its primary efficacy endpoint is the superiority of progression-free survival as determined by the Independent Review Committee (IRC).
While preparing the clinical study report and regulatory documents, it was noted that the IRC did not receive the complete trial data available in the clinical database at the preliminary review.
This was followed by an analysis of all 495 participants to compare the information submitted to the IRC to that available in the clinical database.
Findings led to the re-evaluation of data gathered from 29 patients.
The final analysis showed that melflufen met the primary endpoint versus pomalidomide with a Hazard Ratio (HR) of 0.792 as established by the IRC.
However, the HR of overall survival was 1.104 in favour of pomalidomide in the intention to treat the population. Overall survival was a key secondary goal in the Phase III trial.
After the OS data analyses, Oncopeptides said that the results are mainly clarified by significant HR differences between subgroups in both directions.
Due to large differences in overall survival in pre-specified subgroups, the FDA called for the partial clinical hold.
The company will work with the FDA on required analysis to gain insights into the benefit/risk profile of melflufen and detect relapsed refractory multiple myeloma patients who can benefit from the drug in earlier lines of treatment.