A recent study published in the Journal of Clinical Oncology determined that patients who achieved very good partial response (VGPR) or better after high-dose chemotherapy and stem cell transplantation experienced significantly longer event-free and overall survival.

“Very good partial response” is one of the terms defined by the International Myeloma Working Group (IMWG) to categorize how patients respond to treatment. According to IMWG criteria (see related Beacon news), patients reach very good partial response when the level of abnormal “M” proteins in their blood decreases by 90 percent.

Previous studies evaluating high-dose chemotherapy have shown that major tumor reduction as indicated by at least very good partial response is associated with increased progression-free and overall survival. In this study, researchers further examined the relationship between very good partial response and long-term prognosis.

Researchers analyzed the data of patients who participated in the 1999 trials conducted by Intergroupe Francophone du Myelome (IFM 99-02 and 00-04). In both trials, patients received a combination induction therapy of vincristine (Oncovin), doxorubicin (Adriamycin), and dexamethasone (Decadron), known as VAD.

Of the 680 patients evaluated for response to induction, 27 (4 percent) achieved complete response, 81 (12 percent) reached very good partial response, 337 (50 percent) achieved partial response, and 235 (34 percent) experienced less than partial response.

Next, patients underwent double autologous stem cell transplants, in which their own previously-collected stem cells were transplanted back into their bloodstream. Of the 802 patients included in the analysis, 445 (55 percent) achieved at least very good partial response, 288 (36 percent) reached partial response, and 69 (9 percent) experienced either stable disease or disease progression. The median follow-up time was 67 months.

Researchers observed that event-free survival – the time passed without disease progression, relapse, or death – was significantly longer in patients who had very good partial response or better than in those who achieved partial response (42 months versus 32 months, respectively). This translated into a five-year event-free survival rate of 34 percent in VGPR-or-better patients versus 26 percent in patients with partial response. Patients with very good partial response also experienced significantly greater five-year overall survival rate (74 percent versus 61 percent).

Researchers determined that as a single factor, partial response or less is an indicator of a shorter event-free and overall survival. Based on their results, researchers concluded that achieving very good partial response should serve as a major treatment goal for patients and their physicians – not only does it correlate with better short- and long-term event-free and overall survival, but it also encapsulates a larger population of patients than complete response.

For more information, please see the Journal of Clinical Oncology (abstract).