Autologous Bone Marrow transplantation - Blog Science Connections

62 Acute Leukemia - AML (Purging)
(4). Two antibodies, PM-81 and AML-2-23, are directed against
antigens associated with myeloid cells (5,6). PM-81 is an IgM antibody
that binds to the lacto-N-fucopentaose III (LNF III) moiety on
myeloid cells, an oligosaccharide expressed on glycolipids and
glycoproteins. It is designated as CD 15 in the International Workshop
cluster designation for monoclonal antibodies. AML-2-23 is an IgG2b
MoAb that reacts with a 55kD glycoprotein designated as CD 14,
primarily present on AML M4 and M5 blast cells. Greater than 90%
of myeloid leukemia blast cells express at least one of these antigens
(7,8). Both antibodies are cytotoxic in the presence of complement.
Moreover, they are cytotoxic to leukemia progenitor cells in at least
two-thirds of patients tested (9). They are minimally toxic to normal
myeloid precursors by the CFU-GM assay, but have no suppressive
effect on BFU-E colony formation. Therefore, they appear to be ideal
candidates to eliminate residual leukemia cells from remission marrow
prior to ABMT.
To date we have transplanted 27 patients in 1st, 2nd and 3rd
remission (Table 1). Each has received cyclophosphamide 60 mg/kg
for 2 days, and 1200 cGy of TBI (200 cGy b.i.d. for 3 days) prior to
ABMT. The mean follow-up time is 19 months. One of the 3 patients
in 1st remission at the time of transplant has relapsed at 9 months but
is currently alive undergoing re-induction therapy (Table 2). Eight of
the 18 patients in 2nd remission have relapsed at times ranging from
3-21 months. Seven of these relapsed patients have died. One patient
received a second autologous transplant and is alive in complete
remission 24 months after the 2nd ABMT. Three patients died of
bleeding problems secondary to poor platelet engraftment at 3, 3, and
8 months. Five patients are alive in complete remission (28%) from 2-
48 months after transplant.
One of 6 patients in 3rd remission has relapsed at 5 months. Two
remain alive (33%) although only 1 is in complete remission. We have
seen no correlation between the rate of hematologic recovery and the
number of nucleated bone marrow cells or CFU-GMS infused.
Table 1. Patient Characteristics
Remission
Number of
Patients Male Female Age (range)
1st 3 2 1 34-43
2nd 18 11 7 11-53
3rd 6 3 3 28-53