Angiogenesis

Image by Louis Heiser

and Robert Ackland

VIENNA—Combining a novel agent with dexamethasone can produce successful results where other treatments have failed, according to a presentation at the 20th Congress of the European Hematology Association.

Researchers tested low-dose dexamethasone in combination with melflufen, a peptidase-targeted therapy and antiangiogenic compound, in a phase 1/2 study of patients with relapsed or relapsed-refractory multiple myeloma (MM).

The treatment produced an overall response rate of 52%, and, although grade 3/4 hematologic adverse events were common, there were few serious adverse events related to melflufen.

These results were presented at the meeting as abstract P285.* The research was sponsored by Oncopeptides AB, the company developing melflufen.

Drug dosing and patient characteristics

In the phase 1 portion of this study, researchers evaluated 4 dose levels of melflufen—15 mg, 25 mg, 40 mg, and 55 mg—on day 1 with 40 mg of dexamethasone on days 1, 8, and 15 of 21-day cycles in a standard 3+3 design. Eight cycles of therapy were planned, but patients could continue on treatment if they experienced a clinical benefit.

There were no-dose limiting toxicities (DLTs) when melflufen was given at the 3 lower doses. However, 4 of the 6 patients who received the 55 mg dose experienced DLTs of prolonged and severe neutropenia and thrombocytopenia.

So the researchers said the MTD of melflufen, when combined with 40 mg of weekly dexamethasone, was 40 mg every 21 days.

In the ongoing phase 2 portion of the study, 29 patients have received melflufen at the MTD. The median time from the patients’ MM diagnosis to the first dose of melflufen was 5.5 years (range, 1-15), and their median number of prior therapies was 4 (range, 2-11).

Nineteen of the patients were refractory to an immunomodulatory drug (IMiD) or a proteasome inhibitor (PI); 11 were refractory to an alkylator; 10 were refractory to both an IMiD and a PI; and 5 were refractory to an IMiD, a PI, and an alkylator.

Safety data

Among the 29 patients in the phase 2 portion of the study, 22 had treatment-related grade 3-4 adverse events. These included thrombocytopenia (59%), neutropenia (48%), anemia (31%), leukopenia (21%), asthenia (7%), fatigue (7%), hyperglycemia (7%), and pyrexia/fever (7%).

To date, 12 serious adverse events have been reported in 8 of the phase 2 patients. Three events in 3 patients were considered related to melflufen—2 cases of febrile neutropenia and 1 case of pyrexia.

Fifteen patients discontinued therapy, 8 due to adverse events, 6 due to disease progression, and 1 after completing all planned cycles of treatment.

Efficacy data

Twenty-one patients were evaluable for efficacy according to the protocol, meaning they had received 2 or more cycles of therapy and completed response assessments after cycle 2.

Four patients withdrew from treatment after 1 cycle due to rapid disease progression and were included in a second response assessment (n=25). It was too early to evaluate the remaining 4 patients.

Among the 21 protocol-evaluable patients, the overall response rate was 52%, and the clinical benefit rate was 67%. Eleven patients achieved a partial response, 3 had a minimal response, 6 had stable disease, and 1 had progressive disease.

Among all 25 evaluable patients, the overall response rate was 44%, and the clinical benefit rate was 56%.

The median progression-free survival for these patients was 7.6 months (range, 3.4 months to not reached).

The researchers said enrollment in this trial is ongoing, with the goal of reaching 55 patients to further characterize the safety and efficacy of melflufen in heavily pretreated MM patients.

*Information in the abstract differs from that presented at the meeting.

Combo shows promise for heavily pretreated MM