A statistical analysis of two Phase 3 trials found relapsed and refractory multiple myeloma patients who achieved complete remission and very good partial response to Revlimid and dexamethasone combination treatment had higher overall survival rates and longer times to disease progression compared to patients who only achieved partial response.

The analysis also showed that patients’ response to Revlimid and dexamethasone improved over time with continuous treatment.

The authors of the analysis therefore suggested continuing treatment in patients who achieved partial response as long as possible to achieve best outcome.

They added that treatment of multiple myeloma should not only focus on achieving an initial response, but on achieving best outcome by treating patients beyond initial response.

Recent studies have shown that more relapsed and refractory patients achieve a complete or very good partial response with the Revlimid (lenalidomide)-dexamethasone (Decadron) combination treatment However, it is not clear if the quality of response is associated with better prognosis.

Researchers therefore analyzed the data from two previous Phase 3 trials to determine whether achievement of a complete remission or a very good partial response confers a clinical benefit over the achievement of a partial response.

Of the 353 relapsed and refractory myeloma patients who received Revlimid and dexamethasone, 32 percent achieved a complete remission or a very good partial response, while 28 percent achieved a partial response.

The median duration of response to the Revlimid-dexamethasone combination was longer for patients who achieved complete remission or a very good partial response (24 months) than those who had only achieved a partial response (8.3 months).

The median time to disease progression for patients who achieved a complete remission or a very good partial response was also longer (27.7 months) than those who had achieved a partial response (12 months).

After four years, 60 percent of patients who had achieved a complete remission and a very good partial response were alive, compared to 42 percent of those who had achieved a partial response.

Median overall survival had not been reached for the complete or very good partial response group, while for the partial response group median overall survival was 44.2 months.

Researchers also found that after four years, 33 percent of patients who achieved a complete remission or very good partial response experienced disease progression. Of those who had achieved a partial response, 56 percent experienced disease progression.

The analysis also showed that the disease status of the participants generally improved as the trial progressed. Of the patients who achieved a partial response as initial response, 50 percent achieved complete remission or very good partial response with continued treatment.

Of the patients who achieved a complete remission or a very good partial response as best response, 82 percent had initially achieved a partial response at first evaluation.

It was also confirmed that the sooner a patient achieved a partial response, the greater the probability of achieving a very good partial response or complete remission with further treatment.

Patients who achieved a partial response by the fourth cycle had a 43 percent chance of achieving a complete response or very good partial response later, while those who achieved a partial response by the sixth cycle had a lesser chance of 38 percent.

Side effects were similar for patients who achieved complete remission or a very good partial response and those who achieved a partial response. The most common severe side effects included low white blood cell counts, low platelet counts, and blood clots.

For more information, please see the full analysis in Haematologica (pdf).