The results of a recent analysis suggest that the dosage of re-infused lymphocytes during an autologous stem cell transplant does not affect relapse or survival rates in newly diagnosed multiple myeloma patients.

“These findings would seem to indicate that, in the context of upfront autologous stem cell transplantation, the proportion of the lymphocytes re-infused is not associated with outcome. In the salvage setting, further analysis needs to be done,” said Dr. Laura Percy of University College London and lead investigator of the study.

High-dose chemotherapy followed by autologous stem cell transplantation is a common treatment option for newly diagnosed myeloma patients under the age of 70. In this procedure, stem cells are collected from a patient’s blood prior to high-dose chemotherapy. The patient then receives these cells following chemotherapy to replace the cells destroyed during treatment.

While stem cell transplantation has demonstrated clear benefits in progression-free and overall survival, little is known about the potential contribution of other blood cell types that also can be re-infused during the transplantation process.

Results of a 2004 analysis, conducted and led by Dr. Luis Porrata of the Mayo Clinic in Rochester, Minnesota, suggested that patients receiving more than 500 million lymphocytes per kilogram of body weight as part of their stem cell transplant had improved progression-free and overall survival.  However, a later study reported that while the lymphocyte dose after chemotherapy led to faster lymphocyte recovery, it did not have an effect on survival outcomes.

In the current study, Dr. Percy and her colleagues sought to determine whether or not the dosage of re-infused lymphocytes as part of a stem cell transplant would affect clinical outcomes.

They retrospectively analyzed data from 251 myeloma patients who had received a transplant at the University College Hospital in London as part of upfront therapy between 1993 and 2008.

Of the 251 patients included in the analysis, 20 percent received stem cells that only contained an insignificant amount of lymphocytes. The remainder of the patients received stem cells that contained a median of 90 million lymphocytes/kg.

The median follow-up time was 39 months.

At six months post transplant, 53 percent of patients achieved at least a very good partial response, 36 percent achieved a partial response, 4 percent reached stable disease, and 7 percent progressed or died. There was no significant difference in response rates between patients who received stem cells with and without lymphocytes.

Overall, the median progression-free survival was 22 months and the median overall survival was 62 months.

The researchers did not find any statistically significant difference in either survival measure between patients who received stem cells with insignificant amounts of lymphocytes, those who received stem cells with less than 90 million lymphocytes/kg, and those who received stem cells with more than 90 million lymphocytes/kg .

In correspondence with The Beacon, Dr. Porrata -- the author of 2004 study that found an impact of lymphocyte dose on transplant outcomes -- noted that his study evaluated recovery and survival measures after patients received a significantly higher median dosage of re-infused lymphocytes compared to the doses reported in the current study.

“It would have been interesting to see if Dr. Percy had used a higher cut-off point than 90 million lymphocytes/kg if there was a further difference in survival,” said Dr. Porrata.

One important difference between the current study and the 2004 Porrata study is that the current study focused solely on newly diagnosed myeloma patients who received stem cell transplants.  The 2004 study by Dr. Porrata included both newly diagnosed as well as relapsed myeloma patients.

In the current study, factors that influenced outcomes after stem cell transplantation were gender, depth of response before the transplant, and progressive disease following initial therapy or transplantation.

For more information, please see the study in the British Journal of Haematology (abstract).