The Impact of Comorbidity on Quality of Life in Chronic Myeloid Leukemia Patients with Deep Molecular Response Who Stopped Therapy By Tyrosine Kinase Inhibitors: Results of the RU-SKI Trial

Background

The data on quality of life (QoL) in chronic myeloid leukemia (CML) patients (pts) with deep molecular response (DMR) in the treatment-free remission (TFR) studies are limited. The influence of comorbidities on QoL in CML pts before and after tyrosine kinase inhibitors (TKIs) discontinuation has not been studied.

Aim

We aimed to study the impact of comorbidities on QoL in CML pts before and after the stop therapy by TKIs.

Patients and methods

The chronic phase (CP) CML pts who had received therapy by any TKI ≥3 years (yrs) with sustained DMR (BCR-ABL ≤0.01% IS) during ≥2 yrs were enrolled into the prospective TFR study RU-SKI. A regular qPCR with BCR-ABL IS evaluation was performed after TKI cessation. TKI were resumed in pts with major molecular response loss (MMR loss, BCR-ABL>0,1%). The QoL was evaluated by RAND SF-36 questionnaire at baseline before TKI stop and at 1, 3, 6, 12 mo during TFR. Eight functional scales were assessed: physical functioning, role limitations physical, bodily pain, general health perceptions, energy/vitality, social functioning, role limitations emotional, mental health. The Integral QoL Index (IQoLI) was calculated based on the scales. Mann-Whitney test, paired Wilcoxon test χ² were used for the statistical analysis. Molecular relapse free survival (MRFS) was evaluated by Kaplan-Meier method, log-rank test was used for comparison.

Results

The analysis was performed in the group of 97 CML pts. Median (Me) age was 47±14.5 (yrs), 48.5% were males. The TKI before treatment cessation were as follows: imatinib and second-generation (2G) TKIs in 67 (70%) and 30 (30%) pts accordingly; 9 (30%) pts received 2G TKIs in 1st line and 21 (70%) pts in 2nd line. Me time of observation was 25 mo (range 12-42).

Comorbidities were present in 81 pts (82%) at baseline. The most frequent comorbidities were cardiovascular (38.4%), gastroenterological (29.3%) and musculoskeletal disorders (27.3%).

First we compared baseline QoL in 2 pts groups: group 1 - pts with acute comorbidity status at baseline (n=42), group 2 - pts with stable comorbidity status (n=29) and with no comorbidity (n=16). QoL in group 1 was significantly worse by all functional scales, except mental health (p<0.05). The IQoLI at baseline was significantly lower in group 1 vs group 2: 0.477 vs 0.589 (p<0.001).

Then we evaluated QoL at 3 mo after TKI stop in 72 available pts, as acute status comorbidity remained in 30 pts. The majority of pts exhibited QoL improvement or stabilization by all SF-36 scales. The most pronounced positive changes were observed by SF-36 scales in pts with acute comorbidity status (group 1).The proportion of pts with QoL improvement at 3 mo after TKI stop was higher in group 1 as compared to group 2 by physical functioning (57% vs 29%), role physical functioning (30% vs 5%) and social functioning (40% vs 24%), p<0.05. Increasing of social functioning was statistically significant: ∆20.2 in group 1 vs ∆12.6 in group 2 (p=0.005). The proportion of pts with QoL worsening at 3 mo after TKI stop was similar in both groups.

MRFS at 24 mo was 62% (CI 46-77%) and 45% (CI 32-58%) in groups 1 and 2 respectively, with no significant differences between the groups (p=0.107).

Conclusion

CML pts with DMR and acute comorbidity status had a worse QoL before TKI therapy cessation compared to pts without comorbidity or with comorbidity in remission. The majority of pts exhibited QoL improvement or stabilization in early terms after TKI stop. Pts with acute comorbidity status had more pronounced positive QoL changes after treatment cessation than other pts. Possible explanation is that TKI therapy could increase the clinical symptoms manifestation by overlapping with the treatment toxicity effects. The molecular relapse rate was similar in pts with and without acute comorbidity status. Thus, comorbidity is not a factor which may have negative impact on the outcomes of stop TKI therapy in CML pts.