Multiple Myeloma Patients Had Continued Response to ASCT Past 100-Day Disease Assessment

Patients with multiple myeloma who underwent autologous stem cell transplantation may have a continued response to the treatment even after the traditional disease assessment at 100 days. A new study indicates that this continued response maintained prognostic value and should be taken into account when considering post-transplant therapies.

“The fact that responses after stem cell transplant continue to improve over time has been observed for a long time,” said study author Shaji K. Kumar, MD, of the division of hematology at the Mayo Clinic, Rochester, Minn.

However, Dr. Kumar added that until now, there was no real estimate as to how often this happened.

“[This] is important when interpreting data from single-arm trials looking at post-transplant therapies, in order to get a better sense of what the additional therapy provided over and above what would have happened in due course of time after a transplant,” Dr. Kumar said.

In this study published in Blood, Dr. Kumar and colleagues looked at outcomes in 430 patients with multiple myeloma after autologous stem cell transplantation. All patients underwent treatment within 12 months of their diagnosis and none had achieved complete remission 100 days post-transplant. All responses were classified by the International Myeloma Working Group criteria.

“Nearly a third of the patients had improvement in their responses beyond the 100 day mark, which is typically used for assessing response to transplant,” Dr. Kumar said. “In addition, we found that patients with this continued response did better overall, suggesting biological differences.”

At evaluation, 39% of patients had a continued response to treatment at a median of 9.4 months post-transplantation. Patients who continued to respond were found to have a longer progression-free survival than patients who did not (35 months vs 13 months; P < .001). In addition, continued responders had longer time to next therapy (43 months vs 16 months; P < .001) and a longer overall survival (96 months vs 57 months; P < .001) compared to patients without continued response.

The researchers wrote that among the factors predictive of a continued responses were having an IgG isotype (P = .0007), a history of an antecedent plasma cell disorder (P = .05), and a day 100 bone marrow plasma cell percentage of three or less (P = .0014).

Based on the results of this study, the researchers wrote that “utilizing the day 100 response assessment for treatment decisions may be premature in patients who were going to have a continued response without further therapy,” especially in patients already in a very good partial response after transplant.