Background. Allogeneic blood and marrow transplantation (BMT)-associated thrombotic microangiopathy (TM) contributes to transplant-related morbidity and mortality. This report examines the incidence of and risk factors for allogeneic BMT-associated TM in two patient cohorts treated before and after changes in myeloablative conditioning regimen intensity (high vs. standard intensity). Methods. Cohort 1 includes 153 consecutive allogeneic BMT patients who underwent transplantation between April 1994 and October 1997 with an allogeneic BMT-associated TM crude incidence of 12%. Cohort 2 includes 75 consecutive allogeneic BMT patients who underwent transplantation from November 1997 to November 2000 with an allogeneic BMT-associated TM crude incidence of 1%. Results. In cohort 1, matched unrelated donor transplant and methylprednisolone (MP) T-cell depletion (TCD) of donor bone marrow were significantly associated with allogeneic BMT-associated TM by univariate analysis; therefore, a logistic model incorporating these effects was constructed to calculate the expected number of allogeneic BMT-associated TM cases in cohort 2. Seven cases would have been expected, but only one was observed (P=0.003; bayesian predictive test). The multivariate analysis of both cohorts yielded MP-TCD (P<0.001), high-intensity myeloablative conditioning regimens used in cohort 1 (P=0.02), and matched unrelated donor (P=0.03) as significant predictors of time to allogeneic BMT-associated TM. Conclusion. Avoidance of high-intensity conditioning regimens may decrease the incidence of allogeneic BMT-associated TM.

We examined the incidence, risk factors and associated mortality of acute renal failure requiring dialysis (Renal Bearman Grade [BG] 3) in a 3-year cohort of 97 consecutive allogeneic blood and marrow transplantation (alloBMT) patients. In all, 20 (21%) developed Renal BG3 (all died by day +132) and 77 (79%) developed renal insufficiency (Renal BG1-2). Renal BG3 was a contributing or primary cause of death in 18 (90%) patients who continued to require dialysis at time of death. The two Renal BG3 patients whose deaths were not related to renal failure died on day +103 of hemorrhage and day +132 of underlying disease. By univariate analysis, age, unrelated donor, veno-occlusive disease (VOD) and grade III-IV acute graft-versus-host disease with hepatic involvement were significantly associated with Renal BG3. The multivariate model of time to Renal BG3 determined only a prior diagnosis of severe acute GVHD (RR=4.1, 95% CI 1.6-10.3, P=0.003) and VOD (RR=9.1, 95% CI 3.5-23.7, P<0.001) as significant independent predictors. Renal BG3 is generally considered a conditioning regimen-related toxicity. This study demonstrates that Renal BG3 is most commonly a complication of hepatic co-morbidities after allogeneic blood and marrow transplantation and identifies patients with a very poor prognosis.

Volume reduction of umbilical cord blood (UCB) units before infusion is standard in most transplant centers. We examined 26 patients who underwent transplantation from May 1997 to December 2001 with unmanipulated (n=18) or volume-reduced (n=8) UCB units for engraftment. Of 18 unmanipulated UCBT patients, 16 achieved ANC>500/mm(3), a median of 26 days (range, 16-104) post-UCBT; two died before engraftment on days +2 and +14. Of 18 unmanipulated UCBT patients, 10 achieved platelet recovery, a median of 60.5 days (range, 41-144) post-UCBT; eight patients died before platelet recovery +2 to +255 days post-UCBT. These results are similar to several reported studies and our series utilizing volume-reduced UCB units for UCBT. At a median follow-up of 29.5 months, the 100-day and 3-year overall survivals of unmanipulated UCBT were 61.1% (95% CI, 38.6-83.6) and 48.6% (95% CI, 24.8-72.4) and of volume-reduced UCBT were 60% (95% CI, 24.4-95.6) and 22.5% (95% CI, 0-58.7). There was no serious toxicity from UCB infusion using unmanipulated UCB units. We conclude that unmanipulated UCB units may be infused safely into UCBT patients with adequate engraftment and survival.

Rituximab is used for in vivo tumor cell purging for non-Hodgkin's lymphoma (NHL) patients prior to autologous peripheral blood stem cell transplantation (PBSCT). However, its effects on PBSC mobilization and function are poorly understood. We compared the mobilization characteristics and engraftment kinetics of 13 NHL patients receiving and 34 NHL patients not receiving rituximab 6 months before PBSC mobilization. In the rituximab group, there was a significantly longer time to neutrophil engraftment (P=0.0466), a trend toward the need for BM harvest to supplement low-yield PBSC collections (31 vs 9%, P=0.08) and a significantly increased rate of bacteremia episodes (62 vs 26%, P=0.025). Median progression-free survival (PFS) and overall survival (OS) were significantly longer in the rituximab compared to the nonrituximab patients (P=0.049 and 0.042, respectively). However, patients in the nonrituximab group were at high risk for recurrence and expected to have shorter survival. Rituximab used within 6 months prior to collection may have a detrimental effect on PBSC mobilization and engraftment. However, rituximab is a major therapeutic breakthrough for NHL treatment and this negative effect may be offset by improved survival. Further studies are warranted in larger populations to determine the impact of rituximab on engraftment, PFS and OS.

Dr Pitini has raised a very important issue of the effect of immunomodulatory drugs (thalidomide) on the mobilization and collection of stem cells. Data on this issue remain controversial. Ghobrial et al1 presented their data on the role of thalidomide (Thal) and stem cell mobilization in patients with multiple myeloma (MM) as a poster at the Annual ASCO meeting of 2002. Their conclusion was that limited exposure of thalidomide had no effect on stem cell mobilization.

Several trials have shown the activity of thalidomide (THAL) in relapsed multiple myeloma (MM) patients failing PBSCT or conventional chemotherapy. PBSCT is considered standard treatment for most patients requiring therapy for MM; however, patients with VAD-resistant disease may not be able to receive PBSCT due to rapidly advancing disease. We report four cases of VAD-refractory MM salvaged with THAL + VAD followed by PBSCT. All patients underwent stem cell mobilization with cyclophosphamide (Cy) (4.5 g/m 2 ) and GMCSF. Melphalan (140–200 mg/m 2 ) was given as conditioning. All patients engrafted within 12–16 days after PBSCT. Day +100 evaluation showed the following: very good partial response ( n = 1) and complete response ( n = 3). After a median follow-up to 153 days, two patients continue to take THAL with no signs of disease progression. One patient developed CHF and was taken off THAL while another patient has died of progressive disease while on THAL (MTD 50 mg). In conclusion, VAD-refractory patients were salvaged with the addition of THAL to VAD. They were subsequently able to undergo autologous PBSCT for MM, which will likely improve their overall survival. This suggests that THAL and other related immunomodulatory drugs may prove useful for initial MM therapy in combination with standard chemotherapy followed by PBSCT.