Donor lymphocyte infusions (DLI) in patients with chronic myeloid leukemia following allogeneic bone marrow transplantation

Donor lymphocyte infusions (DLI) were given between June 1990 and March 1996 to 18 patients with chronic myeloid leukemia (CML) for the treatment of cytogenetic (n = 6) or hematologic relapse (n = 12) following an allogeneic bone marrow transplant (BMT). Patients were divided in two groups: patients in group A (n = 8) received a large dose of donor lymphocytes (greater than or equal to 1 x 10(8)/kg), whereas patients in group B (n = 10) received escalating numbers of cells (2 x 10(5) up to 2 x 10(8)/kg). The median number of DLI in group A was 2 (range 1-3); the median number of infusions in group B was 7 (range 3-9). Acute GVHD occurred in 12 patients (grades I-III) and was a major cause of death in two. The risk of developing GVHD correlated with the number of cells infused: 37%, 14%, 5% and 0% for DLI with cells greater than or equal to 1 x 10(8), 2 x 10(7)/kg, 2 x 10(6)/kg, and 2 x 10(5)/kg, respectively (P = 0.01). Median transaminase levels were found to be significantly increased in patients with, as compared to patients without, acute GVHD (GPT 412 vs 28 IU/l; P = 0.03). Severe aplasia occurred in four and was a contributing cause of death in two patients. Overall, four patients died as a consequence of DLI and all received > 1 x 10(8)/kg cells: the actuarial risk was 38% in group A and 14% in group B (P = 0.1). There were 10 complete and three partial cytogenetic responses: the actuarial probability at 5 years of being Ph negative was 69%: it was 46% for group A and 85% for group B (P = 0.1). The longest patient is now 6 years post-DLI, Ph negative, BCR-ABL negative. The actuarial 3 year survival is 38% in group A and 86% in group B (P = 0.06). The study confirms that DLI post-PMT is not innocuous and that there is a definite long-lasting antileukemic effect in patients with CML. It also suggests that: (1) the risk of developing GVHD correlates with the number of infused cells; (2) that significant elevations of serum GPT levels are associated with GVHD; and (3) that the use of escalating doses of cells may allow the identification of side-effects and discontinuation of infusions before life-threatening GVHD has developed.