Abstract
Background: Clinical trials exclusively focusing on pts with MDS/MPN are lacking. AZA is a DNA methyltransferase (DNMT) inhibitor approved for the therapy of MDS while RUX is a JAK inhibitor approved as therapy for primary myelofibrosis and polycythemia vera. RUX and AZA may target distinct clinical and pathological manifestations of MDS/MPNs.
Aim: To determine the efficacy and safety of RUX + AZA in pts with MDS/MPN requiring therapy including chronic myelomonocytic leukemia (CMML), atypical chronic myeloid leukemia BCR-ABL1 negative (aCML), and myelodysplastic/myeloproliferative neoplasm, unclassifiable (MDS/MPN-U)(ClinicalTrials.gov Identifier: NCT01787487).
Methods: A sequential approach with single-agent RUX 15 mg orally twice daily (if platelets 100-200) or 20 mg twice daily (if platelets >200) continuously (pts with platelets below 50 were not eligible) in 28-day cycles for the first 3 cycles followed by the addition of AZA 25 mg/m2 on days 1-5 of each 28-day cycle starting cycle 4 was adopted. The AZA dosage could be gradually increased to a maximum of 75 mg/m2. The AZA could be started earlier than cycle 4 and/or at a higher dose in pts with proliferative disease or elevated blasts.
Results: 24 pts were enrolled between March 1, 2013 and April 1, 2015. Baseline characteristics are summarized in table 1. 17 pts remain alive after a median (med) follow-up of 6.0 (3.7 - 21.3+) months. Responses were evaluated by the MDS/MPN IWG response criteria (Savona et al., Blood 2015, 125(12):1857-65). Responses were noted in 12 (50%) pts. Details of responses are shown in table 2. Med time to responses was 1.8 mos (0.7 - 5.5+) and the med duration of response is 7.0 mos (1.8 - 17.6+). Additionally, 9 pts had >5% pretreatment BM blasts: 6 of these pts had follow-up BM evaluations and 3 achieved a reduction in blasts to <5% with a med time to blast reduction of 5.5 mos (5.5 - 11.2+). Serial evaluation of bone marrow biopsies documented reduction in EUMNET fibrosis score in 3 of 11 (27%) evaluable pts after a med of 5.5 mos (2.1 - 5.6+) on therapy. The reduction was by one grade in all 3 pts (MF-2 to MF-1 in 2 pts, MF-1 to MF-0 in 1 pt) and was confirmed on a subsequent BM biopsy in 2 pts.
No pts experienced grade 3/4 non-hematological toxicity. New onset grade 3/4 anemia and thrombocytopenia were seen in 12 (50%; of which 5 had a 2+ grade change) and 8 (31%) pts, respectively. The med overall survival is 15.1+ mos. 7 pts have died: pneumonia (n=3), sepsis (n=2), progression to AML (n=1), and transition to hospice (n=1).
The AZA was started in cycle 4 in 12 pts (50%). The AZA was started earlier due to leukocytosis or increased blasts in 11 pts (46%), in cycle 1 (n=6), cycle 2 (n=4), and cycle 3 (n=1). 13 pts have discontinued protocol therapy due to leukocytosis (n=6), progression to AML (n=1), lack of response (n=3), pneumothorax (n=1), stem cell transplant (n=1), and loss of insurance (n=1), respectively.
Conclusion: Concomitant administration of RUX with AZA was feasible and effective in pts with MDS/MPNs, with expected myelosuppression as the only significant toxicity. This combination warrants further evaluation.
Table 1. Baseline characteristics (N = 24) Characteristic N (%) / [range] Med age, years 71 [55 - 79] Prior treatment 9 (38) Diagnosis MDS/MPN-U CMML aCML 11 (46) 10 (42) 3 (12) MF - DIPSS Int-1/ Int-2/ High 4(17)/ 11(46) / 9(37) MDS - IPSS Low/ Int-1/ Int-2/ High 9(38) /12(50) / 2(8) / 1(4) Splenomegaly 12 (50) Med WBC x 109/L 26.3 [3 - 123.2] Peripheral blood blasts >/= 1% 17 (71%) LDH 1040 [409 - 3567] EUMNET fibrosis grade MF-1/ MF-2/ MF-3 10(42)/ 6(26)/ 1(4) JAK2 + 6 (25) Med JAK2 allele burden 42.2 [3 - 90] Karyotype Diploid Abnormal 18 (75) 6 (25) 28-gene molecular panel in 23 pts*, (1 pt not done) ASXL1 DNMT3A TET2 KRAS/NRAS PTPN11 IDH 2 4 (17) 4 (17) 3 (13) 2(8) / 2(8) 2(8) 2 (8) *Mutations identified in only 1 pt included EZH2, GATA2, RUNX1, MPL, KIT.
Table 2. Response evaluation by the MDS/MPN IWG 2015 criteria Response category Evaluable pts Responders/Evaluable (%) *All responses, some pts have > 1 response All 12/24 (50) Clinical improvement (CI) spleen Pts with palpable spleen > 5 cm 8/11 (73) CI total symptom score Pts with baseline TSS > 20 3/12 (25) CI Hemoglobin (HGB) Baseline HGB < 10 g/dL 1/7 (15) CI Transfusion independence History of transfusion dependence 1/5 (20) Partial marrow response Baseline and follow-up BMs 5/11 (45) Optimal marrow response Baseline and follow-up BMs 1/11 (9) *No CR or PR documented
Disclosures
Daver: ImmunoGen: Other: clinical trial, Research Funding. Cortes:Pfizer: Consultancy, Research Funding; BerGenBio AS: Research Funding; Teva: Research Funding; BMS: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; Ariad: Consultancy, Research Funding; Astellas: Consultancy, Research Funding; Ambit: Consultancy, Research Funding; Arog: Research Funding; Celator: Research Funding; Jenssen: Consultancy. Pemmaraju:Stemline: Research Funding; Incyte: Consultancy, Honoraria; Novartis: Consultancy, Honoraria, Research Funding; LFB: Consultancy, Honoraria. DiNardo:Novartis: Research Funding. Konopleva:Novartis: Research Funding; AbbVie: Research Funding; Stemline: Research Funding; Calithera: Research Funding; Threshold: Research Funding.
Leukemia secondary to myeloproliferative neoplasms
