Charlson Comorbidity Index (CCI) and Hematopoietic Cell Transplantation Specific-Comorbidity Index (HCT-CI) Do Not Predict Transplant Related Mortality (TRM) and Post-Transplant Outcomes In Young Patients Undergoing Reduced Intensity Conditioning (RIC) Umbilical Cord Blood (UCB) Transplantation

TRM, drug toxicities, life-threatening infections, poor quality of life, and graft versus host disease (GVHD) are significant risks of hematopoietic cell transplantation (HCT). In addition to the risks of HCT, existence of pre-transplant comorbidities can have significant impact on transplant outcomes. A comparison of CCI and the HCT-CI revealed that HCT-CI was prognostic and better at predicting TRM and overall survival (OS). However, the HCT-CI and CCI results have been inconsistent in predicting the TRM and OS in validation studies.

In subgroup analyses of a large retrospective trial, HCT-CI did not predict TRM or OS for UCB recipients. Patient heterogeneity in age, disease, disease-risk, comorbidities, and conditioning regimens may have limited validation in these UCB recipients. The design of this research was to explore whether or not the HCT-CI and/or CCI can accurately predict post-transplant outcomes in young patients with high risk hematologic malignancies undergoing uniform RIC UCB transplantation.

A retrospective chart review was performed on 52 consecutive young (age < 55) UCB transplant recipients receiving the RIC regimen fludarabine, cyclophosphamide, ATG, and 200 cGy TBI. All patients had received cyclosporine and mycophenolate mofetil for GVHD prophylaxis. Information on pre-transplant comorbidities was obtained from the CIBMTR pre-TED form for each patient and retrospective chart reviews. Demographic information, ECOG performance status (PS), identification of comorbidities, and post-transplant outcomes were obtained. Between 2005 and 2011, 52 patients age 19 – 54 (median 38) years, 30 males (58%) and 22 females (42%), underwent RIC UCB transplantation with the above regimen.

Most patients had advanced stage or high risk hematologic malignancies; 28 patients had MDS/AML (54%), 8 patients had ALL (15%), while 16 patients had other hematologic malignancies. 39 patients had a PS = 0, while 13 had a PS = 1. Half of the patients were in CR > 2, with the same number receiving more than 2 prior therapies.

8 patients had received a prior autologous HCT, 8 a prior allo-HCT, and one patient had failed a previous UCD transplantation. 11 patients did not achieve engraftment. Median time to neutrophil engraftment was 26 days (95% CI: 24 – 28 d) and median time to platelets engraftment was 38 days (95% CI: 31 – 45 d). No patient developed grade 4 acute GVHD. Grade 3 acute GVHD was seen in 12 / 52 patients (23%). Chronic GVHD was seen in likewise seen in 12 patients (23%). To date 16 patients (30%) have relapsed. OS was 42% and PS was 37% at one year. Median PFS and median OS were 5 months and 7 months, respectively (PFS 95% CI: 1 – 11 months, OS 95% CI: 1 – 13 months). Neither CCI, nor HCT-CI were significant predictors of OS and PFS, however the ECOG PS was significantly associated with an improved OS and PFS (Table).

In a previous presentation our group concluded that CCI performs better than HCT-CI in elderly patients undergoing UCB transplant. When tested in a population younger than 55 years old though, we were unable to validate the generally accepted prognostic indices. It is unclear whether this is due to a selection bias: it appears most of the patients were essentially health from a non-hematological stand-point, and as such the “classic” cardiac or pulmonary risk factors were underrepresented. The excess TRM is likely due to the severity of their underlying disease, and the majority were in CR ≥ 2 and had received multiple previous courses of antineoplastic chemotherapy. As umbilical cord transplants become more utilized, a new prognostic index needs to be developed, more fitting to the patients < 55 years old.