Cytokine Profile Changes In 309 Myelofibrosis Patients: Comparison Of JAK1/JAK2 Inhibitor Therapy Vs. Placebo – Correlative Analysis From The Comfort-I Trial

Inflammatory deregulation may be a major factor in cancer related symptoms (Dantzer Nature Rev Clin Oncol 2012). Improved symptoms in myelofibrosis (MF) patients treated with single arm ruxolitinib (JAK1/JAK2 inhibitor) studies has been correlated with normalization of selected cytokines increased pre-therapy (c-reactive protein, IL-1ra, MIP-1b, TNF-a, and IL-6; Verstovsek NEJM 2010). We sought to assess the impact of JAK1/JAK2 inhibitor therapy on cytokine levels and the relationship between cytokine levels and symptoms prior to and during JAK1/JAK2 inhibitor therapy in the phase III placebo controlled COMFORT-I trial (Verstovsek NEJM 2012).

Cytokine levels (89 cytokines measured at baseline and at weeks 4 and 24) and MF symptoms (assessed by MFSAF 2.0 – Mesa JCO 2013) were collected during the blinded phase of COMFORT-I. Patients were randomized to ruxolitinib vs. placebo. Plasma was used for the measurement of cytokines using Rules-Based Medicine, Inc. (Austin, TX) Human MAP panel. Associations between the MFSAF total symptom score (TSS) and log2-transformed cytokine data were investigated at baseline using Spearman correlations and linear regression. Mixed models were used to assess cytokine and TSS changes over time within each arm and overall. Logistic regression was used to assess the relationship between baseline cytokines and TSS response (>/=50% reduction from baseline) at week 24, and between week 4 cytokine changes and TSS response (>/=50% reduction from baseline) at week 24 within each arm and overall. Mixed and logistic regression models combining data across arms also included terms for visit, arm, and visit-by-arm interaction. All models also included age, gender, and body mass index (BMI). Given the large number of cytokines being investigated, p<0.001 was considered statistically significant. Cytokine values below the limit of detection were set at the lowest limit of detection and 25 cytokines were excluded from statistical analysis due to having more than 30% of data missing or below the limit of detection.

Patients: 309 subjects were randomized in COMFORT-I with median age 68 (range 40-91), 46% female, 50% primary myelofibrosis, and 61% high risk. All 309 subjects had cytokines measured at one or more of the three visits included in this analysis, with 308 having cytokine values paired with a TSS score at the same visit.

Cytokines at Baseline: At baseline, the highest Spearman correlations with symptomatic burden (as assessed by the TSS) were observed for APOA1 (rho=-.21) and FERRITIN (rho=-.20), followed by INTLK5, MIP1A, MMP3, INTLK2, MGB, INTLK1A, and INTLK7 with correlations between -.15 and -.17 (all p<0.01). After adjusting for age, sex, and BMI, VCAM1 and APOA1 were significantly associated with TSS at baseline.

Cytokine and Symptom changes during trial: Changing levels of 5 cytokines were significantly associated with change of TSS over time beyond the change due to visit, arm, visit-by-arm interaction, age, sex and BMI including VCAM1, LEPTIN, TIMP1, B2MICG, and TNFRII. Within the placebo arm, only 5 cytokines significantly changed over time compared to 46 cytokines in the ruxolitinib arm (visit-by-arm interaction was significant for 43 in the overall models). VCAM1, B2MICG, and TNFRII were among the 5 cytokines which changed in the placebo arm, and VCAM1, LEPTIN, TIMP1, B2MICG, and TNFRII were among the 46 cytokines which changed in the ruxolitinib arm. No baseline cytokines and no changes in cytokines at week 4 univariately predicted week 24 TSS response within either arm at the p<0.001 level.

In the first serial assessment of MF symptoms and plasma cytokine levels in the conduct of a placebo controlled trial we found 5 cytokines in which improved levels correlated with decreased MF symptom burden in ruxolitinib treated patients. Development of a multivariate model for predicting symptom response, correlations with splenic response and impact on survival benefit of therapy is ongoing.

No relevant conflicts of interest to declare.