Cellectar clarity fails to win over investors

Many questions raised by a confusing update from Cellectar Biosciences were answered on Wednesday, but investors still seem unconvinced. After falling 19% yesterday, the group’s stock sank another 3% this morning following a conference call to discuss data from the pivotal, uncontrolled Clover-WaM trial of iopofosine I-131 in late-line Waldenström's macroglobulinaemia. One of the missing data points was complete remission rate, and Cellectar said this stood at 7% (although this figure also included very good partial responses). This was lower than an 8% “stringent” complete remission rate reported in January, but the company noted that several patients remained in assessment, so the latest figure could improve. Although there were high rates of grade 3 or greater adverse events like thrombocytopenia and neutropenia, these were described as manageable; there was also one fatal adverse event of infection. Cellectar also clarified that its planned fourth-quarter regulatory filing would be based on the 55 patients presented today, but more data, including PFS and OS, could emerge at the ASH meeting in December. The focus now turns to the potential market for iopofosine I-131; although the company cites an 11,500-strong US relapsed/refractory Waldenström's population, it appears to be focused on 5,700 third-line-plus patients.

The evolving dataset with Cellectar’s iopofosine I-131

Notes: *major response defined as ≥50% IgM reduction; ^”stringent complete remission”; ^^”complete/very good partial response”. Source: company releases.