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Graft failure after allogeneic blood or marrow transplantation, although generally uncommon, can be a devastating complication. This report includes the outcome of nine patients who received a salvage transplant for failure to engraft after one (n = 8) or 2 (n = 1) prior transplants. Eight patients received allografts from the original donor. All received fludarabine 30 mg/m2 i.v. and alemtuzumab 20 mg i.v. daily from days −6 to −2. Daily CYA was begun on day −2, and the allograft was infused on day 0. The therapy was well tolerated with low toxicity, and all nine patients engrafted, recovering neutrophils at a median of 12 days after transplant. Four patients died: two of relapse, one of a fungal infection in the setting of GVHD and one of multiple sclerosis. The combination of fludarabine and alemtuzumab is an effective and well-tolerated salvage conditioning regimen for patients who experience graft failure after blood or marrow transplants.
Graft failure is rare in recipients of allogeneic blood or marrow transplantation (BMT) from HLA-identical donors in the absence of T-cell depletion, but can occur in greater than 10% of T-cell-depleted or HLA mismatched transplants.1,2 Graft failure can occur early before any evidence of neutrophil recovery or late after transient donor engraftment. In addition to T-cell depletion and HLA-mismatch, factors such as poor graft quality, reduced-intensity conditioning regimens and alloimmunization can also be associated with increased rates of graft failure, and in many cases the cause is probably multifactorial.1–5 Regardless of the cause, the outcome with a second transplant has historically been rather poor because of high rates of infections, extramedullary organ toxicity, and GVHD.2,6–16 Thus, we hypothesized that the optimal second BMT strategy for salvaging graft failure should involve substantial immunosuppression and high doses of donor cells, whereas at the same time limiting cytotoxicity and GVHD.
We report on a salvage transplant strategy using a conditioning regimen of alemtuzumab and fludarabine. These drugs are frequently administered in BMT conditioning regimens, especially those of reduced intensity, because of their potent immunosuppressive properties but limited cytotoxic properties. Alemtuzumab is an MoAb directed against CD52, and fludarabine, through its metabolites, acts as an inhibitory substrate for ribonucleotide reductase, the DNA polymerases, DNA ligase I and DNA primase secondarily affecting transcription through incorporation into RNA.17,18 In addition, pretransplant alemtuzumab has an elimination half-life of approximately 12 days, and the antibody will still be present at the time of allograft infusion, thus generating some degree of in vivo T-cell depletion as GVHD prophylaxis.18
This is a retrospective review of all patients who received a salvage allogeneic BMT for graft failure since September 2001 at the Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins. The diagnosis of graft failure was made when patients beyond day 30 after allogeneic BMT failed to show both neutrophil recovery and any evidence of donor origin DNA in chimaerism studies by PCR of variable nucleotide tandem repeats. Regardless of the primary diagnosis, patients received fludarabine 30 mg/m2 i.v. and alemtuzumab 20 mg i.v. daily from days −6 to −2. On day −2, they began CYA 5 mg/kg i.v. over 6 h every day. The allograft was infused on day 0. On day +3 after BMT, CYA was decreased to 2.5 mg/kg i.v. and then given orally when the patient could tolerate it for 6 months. On day +5 after BMT, 5 µg/kg G-CSF was given until neutrophil recovery to more than 500/µl. The standard antibiotic prophylaxis included sulphamethoxazole/trimethoprim (160 mg trimethoprim component or single strength) p.o. every day for 6 months starting on day 21, valacyclovir 500 mg. p.o. 3 times a day until day 28, fluconazole 400 mg p.o. every day and norfloxacin 400 mg p.o. twice a day until neutrophil recovery.
Between September 2001 and March 2007, nine consecutive patients who failed to engraft after an allograft were re-transplanted (Table 1). The median time between failed transplant and salvage allograft was 62 days (range 43–84). All patients had a BM biopsy before the salvage transplant, and in all cases the marrow was aplastic except in one (patient number 2) who was hypocellular (<5%) and only showed persistent CLL but no haematopoietic progenitors. In eight patients, the salvage transplant followed their first allograft, whereas in another patient it followed after a second transplant. One patient (number 9) received tacrolimus (1 mg i.v./day starting on day −1) instead of CYA. All patients engrafted; eight exhibited 100% donor chimaerism by molecular studies around day 60, whereas one died with neutrophil recovery but before donor chimaerism studies were performed. Engraftment was rapid with neutrophils reaching 500/µl at a median of 12 days after transplantation (range 10–25). Three patients never recovered their platelets (platelet recovery was defined as the first day of a platelet count > 20 000/µl without a platelet transfusion in the preceding 7 days). Of the six who did, the median time to recovery was 21 days (range 16–46). One patient received a BM allograft and eight were transplanted with mobilized peripheral blood stem cells. Characteristics of the grafts are listed in Table 2. The outcome of the nine patients is listed in Table 3. There were two cases of GVHD: one patient had skin-only acute grade II, and the second had grade II acute and later chronic of the skin-mild chronic, according to the NIH consensus definition,19 and limited according to the Seattle definition.20 Both patients responded to steroid-based therapy for the acute phase, and no therapy was given to the patient with chronic GVHD as she was asymptomatic and by now free of clinical manifestations. Of the nine patients, five are alive and in remission with a performance status of ECOG 0 at their last visit. One patient died of a fungal infection in the setting of GVHD therapy 37 days after BMT, one died of progressive multiple sclerosis without evidence of disease, and two died of relapse. No CMV reactivation was seen on any patient (seven as screened by polymerase chain reaction in blood and two by pp65 antigen monitoring). Only one long-term survivor developed a probable fungal infection (pneumonia) that responded well to liposomal amphotericin. As of 30 June 2008, the median overall survival is 453 days (range 37–821).
Historically, the outcome of patients with graft failure following myeloablative allogeneic BMT is poor.2,6–9 In particular, the lengthy periods of neutropenia lead to high rates of severe infectious complications.6 Rates of severe extramedullary end-organ toxicities and of GVHD are also high. The high extramedullary conditioning regimen toxicity rates probably are the result of using two conditioning regimens in a short period of time, whereas the high rate of GVHD is most likely multifactorial and includes intensive conditioning and attempts to enhance engraftment at the expense of GVHD.18
Multiple regimens have been used for second transplants for graft failure, but most have included high-dose CY because of its potent immunosuppressive properties.6,9,13–15 However, its cytotoxic properties may be at least partly responsible for the high rate of conditioning regimen-related toxicity. Fludarabine and alemtuzumab are potent immunosuppressives with limited non-haematologic cytotoxic properties, which have led to their wide and effective use in reduced-intensity conditioning regimens. Moreover, as already discussed, pretransplant alemtuzumab has GVHD-modifying effects.18 Recently, Chewning et al.21 reported that 15 of 15 patients engrafted after undergoing a second BMT for graft failure with fludarabine-based conditioning regimens. Byrne et al.22 also reported on 9 patients engrafting out of 11 patients treated with fludarabine, CY and alemtuzumab for a salvage BMT. Jabbour et al.16 also reported on nine patients receiving a salvage BMT with fludarabine and antithymocyte globulin, six engrafting and developing GVHD, and there was only one survivor with extensive chronic GVHD. Ayas et al.23 recently reported on four patients with Fanconi’s anaemia receiving a salvage BMT after antithymocyte globulin; three engrafted and are long-term survivors, whereas encouraging the Ayas series is exclusively in Fanconi’s anaemia patients and is thus not necessarily applicable to standard haematologic malignancy patients.
Fludarabine and alemtuzumab proved to be effective and well tolerated, with 100% donor engraftment in all patients, only one transplant-related death, and five of the nine patients surviving at a median of 453 days. Although larger trials, possibly comparing different salvage-conditioning regimens, would be ideal, the rarity of graft failure makes this unfeasible. Nevertheless, although rare, graft failure remains an important complication of allogeneic transplantation. Using this combination as salvage conditioning offers the potential advantage of excluding additional cytotoxic therapy and its attendant toxicities. The small patient numbers and heterogeneity of diseases preclude firm conclusions about the long-term disease control with this approach. However, the combination of myeloablation (from the failed BMT) and complete donor chimaerism suggests that these patients should fare no differently from similar patients engrafting after the initial myeloablative regimen.
This research was supported in part by the Grant CA15396 from the NIH. This study was presented in part at the 2008 Meeting of the American Society for Blood and Marrow Transplantation in San Diego, CA, USA.