Thalidomide plus prednisone with or without danazol therapy in myelofibrosis: a retrospective analysis of incidence and durability of anemia response

Low-dose thalidomide and prednisone alone or combined are effective therapies in some persons with primary myelofibrosis (PMF) and anemia with or with RBC transfusion dependence. Danazol is also effective in some persons with PMF and anemia. Responses to these drugs are typically incomplete and not sustained. It is unclear whether adding danazol to thalidomide and prednisone would improve efficacy. We retrospectively compared the outcomes of 88 subjects with PMF and anemia receiving thalidomide and prednisone without (n = 46) or with danazol (n = 42). The primary end point was anemia response, which was 71% (95% confidence interval (CI), 57, 85%) in subjects receiving thalidomide/prednisone/danazol compared with 46% (32, 60%; P = 0.014) in those receiving thalidomide/prednisone. Response rates in subjects who were RBC transfusion dependent was also higher in the danazol cohort (61% (38, 84%)) vs. 25% (6, 44%); P = 0.024). Time to response was rapid (median, 2 months (range, 1–11 months)) and similar between the cohorts. Response duration was longer in the thalidomide/prednisone/danazol cohort (HR 2.18 (1.18–5.42); P = 0.019). Adverse effects were mild and similar between the cohorts. In conclusion, thalidomide/prednisone/danazol seems superior to thalidomide/prednisone in persons with PMF and anemia. Our conclusion requires confirmation in a randomized trial.

Thalidomide is active in PMF because of its antiangiogenic, cytokine regulatory, and immune-modulating properties 8,9 . Thalidomide, 100-400 mg/day, is reported to improve anemia in 20-60% of subjects [10][11][12] . However, these doses are associated with substantial toxicity and are poorly tolerated 10,11 . The combination of low-dose thalidomide, 50 mg/day, and prednisone is better tolerated and results in slightly higher responses than thalidomide alone 13 .
Androgenic steroids reverse anemia by stimulating erythropoietin, increasing iron use and reversing telomere loss 14,15 . Danazol, a synthetic androgen with reduced masculinizing activity, is reported to reverse anemia and thrombocytopenia in persons with PMF 16,17 . Combining therapies with different mechanisms of action might be even more effective in reversing anemia. Herein, we report efficacy, safety, and long-time outcome of therapy with low-dose thalidomide and prednisone with or without danazol in subjects with PMF and anemia with or without RBC transfusion dependence.  19 ; (4) no exposure to ESAs, androgens, thalidomide, lenalidomide, or corticosteroids <12 weeks preenrollment; (5) creatinine ≤2 mg/dL, direct bilirubin <2 times upper limit of normal (ULN) and alanine aminotransferase (ALT)/aspartate aminotransferase (AST) ≤3 ULN. Subjects receiving ruxolitinib during the past several years were excluded. Subjects had a pre-therapy physical examination, baseline laboratory assessment of serum chemistries and blood hematologic parameters, bone marrow aspirate and biopsy, and cytogenetic analyses. Prognostic cohort was assigned using the Dynamic International Prognostic Scoring System (DIPSS) 2 for all subjects and DIPSS-plus 3 for those with cytogenetics data. Bone marrow fibrosis was graded using European consensus guidelines 20 .

Therapy
Subjects received thalidomide, 50 mg p.o. at bed time continuously. Prednisone, 0.5 mg/kg/day, was given for 1 month, 0.25 mg/kg/day, for the next month, 0.125 mg/ kg/day for the third month and tapered thereafter. Danazol, 600 mg/day p.o. was given continuously. Patients with neutrophil count <1.0 × 10E + 9/L and/or platelet count <80 × 10E + 9/L were assigned to thalidomide/ prednisone/danazol therapy, the others were assigned to thalidomide/prednisone therapy. Laboratory studies were performed weekly for 12 weeks. Responders continued on their assigned therapy, whereas others stopped. Packed RBCs were transfused for a hemoglobin concentration <60 g/L or symptoms of anemia.

Evaluation of response and adverse events (AEs)
The primary study outcome was anemia response. In subjects with splenomegaly or thrombocytopenia, spleen and platelet responses were also analyzed. Anemia and spleen responses were assessed according to the revised International Working Group for Myelofibrosis Research and Treatment (IWG-MRT) consensus criteria 21 . Thrombocytopenia response was defined as a platelet increase >50 × 10E + 9/L in subjects with baseline platelets <100 × 10E + 9/L. Toxicity was assessed by the National Cancer Institute Common Toxicity Criteria for Adverse Events, Version 4 22 .

Statistical analyses
Follow-up was to death or 10 June 2017. Quantitative data are expressed as median and range and qualitative data as percent. Baseline variables were compared between cohorts using χ 2 test for categorical variables and Mann-Whitney U-test for continuous variables. Clinical responses were compared between cohorts with χ 2 test. Logistic regression was used to assess relationships between baseline variables and outcomes. Variables significant in univariate analyses were included in the multivariate analysis. Response duration was defined as the interval from anemia response to loss of response, change of therapy, or death. Response duration was calculated using the Kaplan-Meier method and compared by the log-rank test. P-values are two-sided and statistical significance defined as P < 0.05. Statistical analyses were performed using the IBM SPSS 22.0 package (SPSS, Chicago, IL, USA).

Adverse events
AEs were dose dependent and reversible with similar incidences (save ALT/AST increases) and severities in the cohorts. No subject discontinued therapy because of drug-related AEs. Leukocytosis and thrombocytosis occurred in 19% (11, 27%) and 24% (15, 33%) of subjects. There was no thrombo-embolic event. The most frequent non-hematologic AE was increased ALT/AST in 19% (8, 31%) of subjects receiving thalidomide/prednisone/danazol compared with 4% (3, 22%; P = 0.07) of subjects receiving thalidomide/prednisone. Other nonhematologic AEs were less frequent and did not differ significantly between the cohorts (Table 3) including increased bilirubin in four, constipation in six, hyperglycemia in six; rash in five; edema in six, neurological symptoms in seven; abdominal distention in four; hypertension in three, somnolence in two, and creatinine elevation in two. There was no case of prostate cancer or hepatic adenoma.

Discussion
Efficacy of low-dose thalidomide/prednisone in persons with PMF and anemia was studied in relatively small series of subjects with variable response criteria and response rates 13,23,24 . We confirmed the efficacy of thalidomide/prednisone using the current IWG-MRT criteria 21 . Importantly, adding danazol significantly increased response. In another recent study, danazol alone was reported to have a response rate of 30% (17, 43%) 17. These data suggest therapy with thalidomide/prednisone/ danazol is better than any component therapy.
Previous studies reported lower serum EPO levels, smaller spleen size, and lower RBC transfusion frequency were associated with higher anemia response rates 17,25,26 . We found such an association only for RBC transfusion dependence, and independence. We also found an  Creatinine elevation 0 2 advantage for combined therapy in subjects who were RBC transfusion dependent. Anemia responses occurred quickly and similarly in the two groups. Median time to response was shorter in our study than a previous study of danazol 17 suggesting thalidomide/prednisone may have accelerated danazol responses. Our data suggest adding danazol to thalidomide/prednisone improves response rates, prolongs response duration in persons with PMF and anemia with and without RBC transfusion dependence. The major limitation of our study is that it was a retrospective analysis and not randomized, and that although the cohorts were similar for known predictive variables we cannot be certain they were comparable for unknown predictive variables. As such, our conclusions require confirmation in a randomized trial.