Outpatient Cytarabine Administration Is Safe and Effective For Consolidation In Acute Myeloid Leukemia
Authors: Allen Marci R. , Aljitawi Omar S. , He Jianghua , Abhyankar Sunil , Ganguly Siddhartha , McGuirk Joseph P , Lin Tara L. 
Published: October 2019

Abstract

Introduction
Although most patients with Acute Myeloid Leukemia (AML) achieve complete remission with induction chemotherapy, further consolidation with chemotherapy or stem cell transplantation (SCT) is recommended in order to prolong remission duration and prevent relapse. Since the 1990’s, high dose cytarabine has been a standard consolidation regimen, with a goal of 3-4 cycles every 28 days and dose adjustments for advanced age. However, there is no data to define the optimal number of cycles or predict if delays in consolidation delivery alter its efficacy. Furthermore, it has not been demonstrated whether outpatient cytarabine is a safe and feasible alternative to repeated inpatient admissions. Our institution has moved to outpatient administration of cytarabine consolidation for eligible patients (reside within 30 minutes of the hospital in private home or American Cancer Society Hope Lodge with full-time caregiver) in an attempt to reduce hospitalization days, cost, and improve patient quality of life by limiting inpatient days. We hypothesized that outpatient administration of cytarabine consolidation is safe and effective without increased treatment delays or AML relapse and represents a potentially cost-saving approach in selected patients.

Methods
We performed a retrospective chart review of 50 consecutive adult AML patients treated with cytarabine consolidation at the University of Kansas from January 1, 2005, to October 1, 2012. Data collected included AML prognostic category, age, inpatient/outpatient cytarabine consolidation, number of cycles, time between treatment cycles, reasons for any delays and duration of remission.

Results
The median age was 52 (ages 20-70). 42% of patients had favorable risk disease, while 20% were high risk and 36% were intermediate risk. High risk patients who received cytarabine consolidation did so due to the lack of suitable stem cell donor or as a bridge while securing a donor for SCT. Intermediate risk patients who received cytarabine consolidation had no matched sibling or unrelated donor or declined SCT in first complete remission. At the time of this writing, 44% were in remission while 56% had relapsed, with a median duration of remission of 391 days (range 94-991 days). Factors which determined whether patients were treated with cytarabine consolidation as an inpatient or outpatient included insurance coverage for outpatient cytarabine and availability of local housing/caregiver. Patients who received inpatient versus outpatient cytarabine were older (median ages of 57 and 44 respectively, p<.01). Inpatient cytarabine was given to 54% of patients, 77% of whom have relapsed. In contrast, outpatient cytarabine was given to 46% of patients, with a significantly lower rate of relapse at 32% (p=0.002). Patients treated with outpatient consolidation more frequently had favorable or intermediate risk AML (92% vs 69% inpatient). The difference in relapse rates remained significant on logistic regression analysis controlling for cytogenetic risk category (p=0.048), although the sample size is small. Delays of more than 7 days between consolidation cycles occurred in 67% of all patients. The most common reasons for delay were infection and prolonged cytopenias. Using Cox regression analysis, there was no significant difference in rates of delayed consolidation cycles between patients treated inpatient or outpatient. There was no statistically significant difference seen in relapse rates whether or not delays in treatment occurred (p=0.13). There were no recorded incidents of ambulatory pump failure. Out of 71 cycles of outpatient cytarabine administered, there were 20 re-hospitalizations, and 20% of patients had re-hospitalization during at least one outpatient consolidation cycle.

Conclusions
The delivery of cytarabine consolidation in the outpatient setting appears safe with no increase in delays in chemotherapy delivery. Although the statistically significant difference in relapse rate favors outpatient cytarabine consolidation, this may reflect inherent AML biology as more patients had favorable risk AML. There was no evidence to suggest inferior outcomes with this approach. This small retrospective sample demonstrates the feasibility of outpatient cytarabine consolidation, avoiding costly and inconvenient hospitalization without compromising the on-time delivery of chemotherapy or clinical outcome.

Disclosures:
No relevant conflicts of interest to declare.