Allogeneic Stem Cell Transplantation (ASCT) and Donor Lymphocyte Infusions (DLI) in the Management of Chronic Myelomonocytic Leukemia (CMML).

Background:

Overall prognosis in CMML is unfavorable. The only curative option is ASCT, yet the limited data available from the largest reported series, reports 2 year overall (OS) and disease free (DFS) survival of only 21% and 18%, respectively [Kroger et al, BJH 2002, 118: 67]. Data on DLI for CMML are generally restricted to case reports. We retrospectively reviewed our experience of ASCT and DLI for adults with CMML.

Patients:

Seventeen consecutive patients (11 males) with CMML underwent ASCT from 1992 to 2004. At transplant, median (range) age was 50 years (26–60), duration of disease 7 months (2.5–44), and bone marrow (BM) blast count 6% (1–58%). Prior to transplant, 11 had evolved into acute myeloid leukemia (AML). Of these, 10 received standard induction chemotherapy but only one achieved complete remission (CR); 5 had persistent CMML and 4 refractory AML. Karyotype at transplant was either normal (n=9) or revealed isolated monosomy 7 (n=4), complex (n=1), or single, nonrecurrent abnormalities.

ASCT:

Conditioning was Cytoxan/Total Body Irradiation in all but one who received a non-myeloablative (NMA) regimen (cladrabine/ATG/thiotepa). Stem cell source was HLA-identical sibling in 14 patients and unrelated in 3 peripheral blood (PB) in 7, BM in 8, or both in 2. Median BM mononuclear cell/kg dose was 2.3 (1.7–4.15) x 10⁸ and PB CD34 cell/kg was 5.12 (0.94–7.29) x 10⁶. Graft versus host disease (GVHD) prophylaxis was cyclosporin alone (n=3), with methotrexate (n=12), or prednisone (n=1) or was tacrolimus/methotrexate (n=1).

Post-transplant course:

All but one patient who died on day 11 of sepsis engrafted (sustained ANC > 500) at a median of 19.5 days (13–31). CR was documented in 13 (76%) post-ASCT. Acute GVHD was grade II-IV (75%) and III-IV (37.5%) and chronic GVHD was extensive (n=37.5%). Seven (41%) demonstrated relapse or persistent disease at a median of 6 months (3–55.5) and 13 (76%) have died due to disease (n=6) or transplant related mortality (n=7).

DLI:

Six patients underwent DLI for morphologic (4 recurrent/persistent CMML, 1 early AML with extramedullary disease) or cytogenetic relapse (n=1), at a median of 19.5 days (6–52) post-relapse. Median BM blast count at DLI was 3% (1–22%). The median CD3+ cell dose infused was 30.45 x 10⁷ cells/kg (11.2–45.5), given in a median of 3 infusions (range: 1–3). Four did not respond, but two (one with cytogenetic and one with morphologic relapse) achieved a durable CR of 15 months each, both had extensive CGVHD, from which one died of complications. The other relapsed but failed to respond to a second DLI and died of disease.

Survival:

For the entire cohort, median DFS and OS were 6 months and 7 months, respectively. At last follow up, 4 remain alive, 3 in continuous CR (18%), at 12, 29 (treated with the NMA regimen) and 116 months, respectively. Of the 3 patients surviving in remission, all had transformed to AML prior to ASCT and only one had achieved CR following induction chemotherapy. Multivariate analysis failed to demonstrate any significant effect of age, duration of disease, BM blast %, karyotype or induction chemotherapy on RFS or OS, likely reflecting the small numbers available for analysis.

Conclusion:

The current study demonstrates anti-CMML activity of both ASCT and DLI although overall outcome is less than encouraging and unpredictable. Novel approaches are needed.