Haploidentical stem cell transplantation for acute leukemia

PREMISE

Since March 1993, 133 patients with high-risk acute leukemia (66 AML, 67 ALL) have received a megadose of T-cell depleted hematopoietic stem cells. The 1993-95 conditioning protocol included TBI, thiotepa, ATG and CY for 36 patients who received an inoculum made up of lectin-separated bone marrow and PBPCs. After 1995, to minimise the extra-hematological toxicity of the conditioning and eliminate GvHD, we substituted fludarabine for CY in the conditioning and PBPCs were depleted of T-cells by a positive selection of the CD34+ cells using CellPro (n=44 patients) or, since January 1999, CliniMacs (n = 53 patients). A later modification to the protocol in January 1999 was the suspension of post transplant G-CSF. WORK IN PROGRESS: We report here the results in the last 53 acute leukemia patients all of whom were transplanted under our modified protocol. Ages ranged from 9 to 62 years with a median of 38 years for the 33 patients with AML and 23 for the 20 with ALL. All were at high risk because 25 were actually in relapse at transplant, 16 were in second or later CR and even the 12 patients in CR1 were at high risk because of the unfavourable prognostic features. Overall 52/53 patients (98%) engrafted. The TBI-Fludarabine-based conditioning was well tolerated even in the 14 patients between 45 and 62 years of age. There was no veno-occlusive disease of the liver and the incidence of severe mucositis was low. Even though no post-transplant immunosuppressive therapy was given, acute GvHD grade > or = II occurred in only 4 cases and only one progressed to chronic GvHD. Overall, 16 patients (30%) have died of non-leukemic causes. Relapses occurred mainly in patients who were already in relapse at transplant (12/25). Only 3 of the 28 who were in any CR at transplant have so far relapsed. As our group has already shown, donor-vs-recipient NK cell alloreactivity exerts a specific graft-vs-AML effect in the absence of GvHD. In fact, leukemia relapse was largely controlled in AML recipients whose donor was NK alloreactive, with only 2 out of 16 relapsing. To date, 13 of 18 AML (72%) and 5 of 10 ALL (50%) who were in any CR at transplant, survive disease-free while 4 of the 15 patients (16%) in relapse at transplant survive. The probability of event-free survival for patients transplanted in CR is 60% in the 18 AML patients and 38% in the 10 ALL. The probability of EFS was significantly better in the 16 AML patients whose transplant included donor vs recipient NK cell alloreactivity than in those whose transplant did not (70% vs 7%). In conclusion, given our current results, the most suitable candidate for the full haplotype mismatched transplant should be in early stage disease and selection of an NK alloreactive donor is recommended.

Total body irradiation-based regimen in the conditioning of patients submitted to haploidentical stem cell transplantation

BACKGROUND AND PURPOSE

To evaluate the efficacy and toxicity of a highly immuno- and myelo-suppressive conditioning regimen followed by the infusion of large numbers of T-cell-depleted mismatched haematopoietic stem cells in 43 high-risk acute leukaemia patients.

RESULTS

A high rate of engraftment (95%) and no graft-versus-host disease (GvHD) were observed. The 4-year probability of event-free survival was 0.25+/-0.09 for acute myeloid leukaemia and 0.17+/-0.07 for acute lymphoid leukaemia patients.

CONCLUSIONS

This study shows that the main obstacles limiting the use of mismatched transplants, i.e. GvHD and rejection, were overcome.

Improved outcome with T-cell-depleted bone marrow transplantation for acute leukemia

PURPOSE

To eliminate the risk of rejection and lower the risk of relapse after T-cell-depleted bone marrow transplants in acute leukemia patients, we enhanced pretransplant immunosuppression and myeloablation.

PATIENTS AND METHODS

Antithymocyte globulin and thiotepa were added to standard total-body irradiation/cyclophosphamide conditioning. Donor bone marrows were depleted ex vivo of T lymphocytes by soybean agglutination and E-rosetting. This approach was tested in 54 consecutive patients with acute leukemia who received transplants from HLA-identical sibling donors or, in two cases, from family donors mismatched at D-DR. No posttransplant immunosuppressive treatment was given as graft-versus-host disease (GVHD) prophylaxis.

RESULTS

Neither graft rejection nor GVHD occurred. Transplant-related deaths occurred in six (16.6%) of 36 patients in remission and in seven (38.8%) of 18 patients in relapse at the time of transplantation. The probability of relapse was .12 (95% confidence interval [CI], 0 to .19) for patients with acute myeloid leukemia and .28 (95% CI, .05 to .51) for patients with acute lymphoblastic leukemia who received transplants at the first or second remission. At a median follow-up of 6.9 years (minimum follow-up, 4.9 years), event-free survival for patients who received transplants while in remission was .74 (95% CI, .54 to .93) for acute myeloid leukemia patients and .59 (95% CI, .35 to .82) for acute lymphoblastic leukemia patients. All surviving patients have 100% performance status.

CONCLUSION

Adding antithymocyte globulin and thiotepa to the conditioning regimen prevents rejection of extensively T-cell-depleted bone marrow. Even in the complete absence of GVHD, the leukemia relapse rate is not higher than in unmanipulated transplants.

Mismatched T cell-depleted hematopoietic stem cell transplantation for children with high-risk acute leukemia

The aim of this study was to extend allogeneic hematopoietic stem cell transplantation to leukemia patients without a matched donor. To prevent graft failure, large doses of T cell-depleted hematopoietic stem cells were transplanted following a highly myeloablative and immunosuppressive conditioning regimen. Fifteen children with high-risk acute leukemia received T cell-depleted hematopoietic stem cells from full-haplotype mismatched family members after a conditioning regimen that included single-dose TBI, thiotepa, ATG and fludarabine. To prevent GVHD, marrow cells were T-depleted by soybean agglutinin and E-rosetting, peripheral blood cells by E-rosetting followed by positive selection of the CD34+ cells. No post-transplant prophylaxis for GVHD was administered. In all patients full donor-type engraftment was achieved. None of the evaluable patients developed either acute or chronic GVHD. Regimen-related toxicity was minimal. Five patients are alive and event-free at a median follow-up of 18 months (range 13-28). All surviving patients have a good quality of life. Seven patients have relapsed. This study shows that GVHD and graft failure, which limited the use of full-haplotype mismatched bone marrow transplants, have been overcome. Since almost all children have a mismatched relative, advances in this area should make mismatched transplants a routine consideration for patients with high-risk leukemia without a matched related or unrelated donor.

Norfloxacin prophylaxis for neutropenic patients undergoing bone marrow transplantation

To prevent bacterial infections in the neutropenic post-transplant period, norfloxacin 400mg twice daily was administered as oral prophylaxis to 44 marrow recipients isolated in laminar airflow rooms (LAFRs). Patients had a mean age of 30 years (8-50) and a male/female ratio of 29/15. The mean duration of prophylaxis was of 41 days (20-80), that of neutropenia (PMN less than 1000 x 10(6)/l) of 31 days (6-76) and that of severe neutropenia (PMN less than 100 x 10(6)/l) of 19 days (10-55). All but two patients developed one or more febrile episodes (total episodes: 71), 33 of which were documented infections. Eighteen bacteraemias occurred and all were caused by Gram-positive cocci: five by coagulase-negative staphylococci (three methicillin resistant), four by coagulase-positive (one methicillin resistant), seven by streptococci (four S. sanguis, one S. milleri, one group B, one group C), and two by enterococci. All streptococcal and enterococcal strains, but only one MR coagulase-positive staphylococcus, proved to be resistant to norfloxacin. Norfloxacin was well tolerated and no prophylactic course had to be interrupted because of side effects. In conclusion, norfloxacin adequately prevents infections caused by Gram-negative bacilli in bone marrow recipients isolated in LAFRs, but Gram-positive infections still remain a problem in these patients indicating the need for improving this prophylactic regimen.

Teicoplanin in empirical combined antibiotic therapy of bacteraemias in bone marrow transplant patients

Teicoplanin in combination with amikacin and ceftazidime was used as empirical therapy in treating 46 febrile episodes in 34 consecutive patients undergoing allogenic bone marrow transplantation. All but four of these febrile episodes occurred in neutropenic patients and 50% of them proved to be bacteraemias (23/46). Cure was achieved in 90% of Gram-positive bacteraemias (18/20) and in six of them teicoplanin was the only antibiotic with activity in vitro against the infecting strain. All (3/3) Gram-negative bacteraemias were cured. Central venous catheter removal was required in five patients (three tunnel infections, one exit-site infection and one thrombophlebitis). Two failures occurred among Gram-positive bacteraemias and in one case the patient died of infection. Four instances of side effects were documented but only one was severe (hearing loss).