Early immune reconstitution and efficient graft vs tumor effect after unrelated partially matched double cord blood transplantation in refractory 8p11 syndrome

The 8p11 myeloproliferative syndrome is a rare hematological malignancy characterized by a CML-like hyperplasia in blood and marrow and a non-Hodgkin's lymphoma involvement in lymph nodes, which are mostly of a T-lymphoblastic subtype. The median survival is <12 months and depends on chemosensitivity and the opportunity to perform rapidly allogeneic hematopoietic cell transplantation.1 We describe here the long-term follow-up of a double cord blood (CB) transplant performed in a 37-year-old patient with refractory 8p11 syndrome. He presented in May 2004 with a marked diffuse tumor syndrome affecting spleen and peripheral lymph nodes (T-cell lymphoma histological subtype) with B signs and elevated lactate dehydrogenase (1500 IU/L) and a myeloproliferative syndrome (WBC 50 G/L). A t(8–13)(p11;q12) translocation was detected in BM and lymph nodes in which additional complex chromosomal anomalies (trisomy 10 and 21; monosomy 13 and 15) were also detected. Molecular tests revealed the presence of the fusion transcript ZNF198 (FIM)-FGFR1. This fusion transcript code for a fusion protein including five zinc-finger domains of the ZNF198 protein and the dimerization domain and two kinase domains of the FGFR1 protein. Absence of the ZNF198 nuclear localization domain leads to a cytoplasmic fusion protein. Moreover, dimerization of FGFR1 (due to the persistence of the P domain) leads to a constitutively activation of the oncogenic Ras/Raf/MEK/MAPK pathway (Figure 1a). The patient received induction chemotherapy consisting of four ACBVP courses (prednisolone 60 mg/m2 from day 1 to day 5, vindesine 2 mg/m2 at days 1 and 5, doxorubicin 75 mg/m2 at day 1, bleomycin 10 mg total dose at days 1 and 5, CY 1200 mg/m2 at day 1) and after 3 months a PR was achieved. In the absence of a matched sibling donor, an allogeneic PBSC transplant was planned but the sole eligible donor was revealed to show active tuberculosis 10 days before stem cell collection. The patient's condition progressed and he was administered second-line platinum-based chemotherapy and obtained a second PR. Considering the severity of the disease, the lack of available stem cell donor and patient weight (80 kg), we planned a double CB unit (CBU) transplantation was planned. Within 1 month two partially matched CBUs were recruited from France (CBU 1) and Spain (CBU 2). Both CBUs were a 4/6 match with the patient and a 6/6 match with each other; DRB1 locus was matched with both CBUs and the recipient; mismatches involved HLA-A and -B loci with no KIR mismatch. From prefreezing data, CBUs contained 5 × 107 nucleated cells (NC) per kg, 6 × 104 CD34 per kg and 1.75 × 104 CFU-GM per kg with, respectively, 2.7 × 107 NC per kg, 4 × 104 CD34 per kg and 1.6 × 104 CFU-GM per kg for CBU 1 and 2.3 × 107 NC per kg, 2 × 104 CD34 per kg and 0.15 × 104 CFU-GM per kg for CBU 2. The transplant was performed 8 months after diagnosis. Just before conditioning, lymph nodes and BM aspirate showed persistent genetic abnormalities. Myeloablative conditioning regimen consisted of fludarabine 25 mg/m2 per day (day −4 to day −2), CY 60 mg/kg per day (day −3 to day −2) and fractioned TBI (6 × 2.2 Gy, day −7 to day −5). GVHD prophylaxis was based on i.v. mycophenolate mofetil (MMF) 500 mg/m2 from day −3 and CsA 2.5 mg/kg from day −1 until discharge; MMF and CsA were then given orally. We infused the richest and best-matched unit first (CBU 1); the second unit was infused 12 h later. After thawing and washing procedures, the patient received 1.7 × 107 NC per kg; 0.44 × 105 CD34 per kg and 1.63 × 104 CFU-GM per kg. Viability of CBU 1 and CBU 2 cells were 35 and 74%, respectively. The patient received G-CSF from day +9 until day +34. No grade >2 conditioning-related toxicity was noted. Neutrophils were recovered (>1 G/L) at day +40 and platelets (>50 G/L) at day +30 post transplant. No infection occurred during aplasia. CsA was stopped at day +90 and MMF at day +240; no sign of acute or chronic GVHD was observed during the 5-year follow-up. The patient returned to his professional occupation 12 months after transplantation and is still professionally active. Complete molecular remission, monitored by RT-qPCR,2 was obtained on day +360 and is still maintained now (Figure 1b). Hematopoiesis was derived exclusively from CBU 1, and full donor chimerism was observed by quantitative PCR3 on day +30 and sustained until the last evaluation at day +1440. Lymphocytes reached normal counts at day +180 and the CD8/CD4 ratio was normalized at day +360. CD4+ T cells counts were 200 per μl threshold at day +180 and increased gradually to 400 per μl at day +360. The last evaluation at day +1440 showed 525 CD4+ T cells per μl (Figure 2a). Thymic-dependent CD4+ T cells recovery occurred early between days +180 and +240 with a transient peak of naive CD4+ CD45RO− CD45RA+ CD31+ T cells (Figure 2b). CD8+ T cells counts increased slowly during the first 2 years and the majority of CD8+ T cells expressed activation markers. A rapid recovery of CD19+ B cells occurred with normal cell counts at day +90 and above the normal range thereafter with no expression of abnormal markers. Natural killer (NK) cells (CD3− CD56+) recovered rapidly and we observed a switch from CD16– immature to CD16+ mature NK cellular pool. This successful double CB transplantation for a disease with a poor prognosis with no evidence of GVHD and no post transplant infections confirm that CB transplantation gives the opportunity to perform rapidly the transplantation in the absence of an available matched unrelated donor.4 CB transplantation with two partially matched CBUs is associated with a better prognosis than single unit transplantation with a decreased relapse risk, an enhanced GVL effect5 that can be curative even for refractory hematological malignancy. The improved EFS and decreased risk of acute GVHD can be explained by the HLA-DRB1 matching of both CBUs with the patient.6 Early lymphocyte recovery after allogeneic hematopoietic SCT is associated with a marked GVL effect with no concomitant increase in GVHD.7 This is supported by data indicating that early lymphocyte recovery decreases leukemic relapse and improves survival in recipients of unrelated CB transplantation.8 We observed an accelerated recovery of CD4+ T cells with a central output of naive thymic emigrants (CD4+ CR45RA+ CD31+ cells),9 which is known to decrease infection mortality rate and to be critical for a long-term beneficial outcome in adults receiving CB transplantation.10 This case report shows that a clear uncoupling between GVL and GVHD mechanisms is possible with a rapid immune recovery even in the context of CB transplantation for a progressive disease. The authors declare no conflict of interest. We thank Frances Sheppard, Clinical Investigation Centre, Besancon for proofreading the article.