Efficacy and safety of pioglitazone in a phase 1/2 imatinib discontinuation trial (<scp>EDI‐PIO</scp>) in chronic myeloid leukemia with deep molecular response
Authors: Katia B.B. Pagnano, Ana Beatriz P. Lopes, Eliana C. Miranda, Márcia T. Delamain, Gislaine O. Duarte, Bruna R.V. Rodrigues, Valquiria M.O. Povoa, Graziele C.P. Furlin, Jessica C. Vianna, Matheus A.S. da Silva, Carmino A De Souza, Erich V De Paula
Journal: American Journal of Hematology (2020)

To the Editor: Treatment-free remission (TFR) is currently a new goal of CML treatment. Successful TKI discontinuation is feasible in approximately 40%-60% of chronic myeloid leukemia (CML) patients with stable and deep molecular response,1 but the persistence of quiescent CML leukemic stem cells (LSC) may be responsible for relapse. Pioglitazone, an antidiabetic drug that is a peroxisome proliferator-activated receptor gamma (PPAR-gamma) agonist, reduced STAT5 activity by suppressing signal transducer and activator of transcription 5 (STAT5) and its downstream targets HIF2α and CITED2. Pioglitazone acts synergistically with imatinib to deplete both proliferating and non-proliferating CML LSC. This action was demonstrated in vitro and, in two CML diabetic patients and in one CML patient treated off-label with pioglitazone. The three patients presented reduction of BCR-ABL levels after pioglitazone was associated with imatinib.2 The rationale of the present study was to associate pioglitazone to imatinib before imatinib discontinuation to eradicate quiescent LSC to improve treatment-free remission success. In this prospective, single-arm, phase 1-2 study (EDI-PIO, from the Portuguese: Estudo de Descontinuação de Imatinibe após Pioglitazona), we evaluated the efficacy and safety of pioglitazone 30 mg/day used in combination with imatinib for 3 months before treatment discontinuation (Clinicaltrials.gov: NCT02852486). (Figure S1). We included CML patients in the chronic phase, treated with imatinib for at least 3 years, with a BCR-ABL1/ABL ratio of ≤ 0.0032% (MR4.5IS) for 2 years. This trial was the first attempt of discontinuation for all patients. The BCR-ABL levels were measured by real-time quantitative RT-PCR (RQ-PCR) in the local laboratory, as previously described and reported in the international scale.3 After discontinuation, patients were monitored monthly in the first year, every 2 months in the second year, and then every 3 months. Imatinib was reinitiated at molecular relapse (RQ-PCR single sample with a value of >0.1% or two consecutive samples >0.01%). Thus, TFR was calculated from imatinib discontinuation until molecular relapse, progression or death to any cause. Between June 2016 and January 2019, we pre-screened 185 patients under treatment with imatinib in our center, of which 56 (30.2%) met the stable deep molecular response inclusion criteria for this study. Thirteen patients did not fulfill the inclusion criteria or were excluded for the following reasons: osteoporosis in treatment (n = 3), previous AP (n = 3), unknown BCR-ABL transcript at diagnosis (n = 2), atypical BCR-ABL transcript (n = 1), irregular follow-up (n = 1), previous allogeneic bone marrow transplantation (n = 2) and renal chronic disease (n = 1). Also, six eligible patients declined to participate and four patients were not contacted about the trial. One patient withdrew consent before initiating the trial (Figure S2). The characteristics of the 32 enrolled patients are shown in Table S1. Most of the patients received generic imatinib (Glimatin®, from EMS S/A and generic imatinib from Cristália Produtos Químicos Farmacêuticos LTDA) since June 2013 (81%). The cut-off date for this data analysis was March 11st 2020. The median time between diagnosis and imatinib start was 2 months (0-68). Regarding treatments for CML before imatinib, 27 patients (84.4%) received hydroxyurea for cytoreduction before starting imatinib for a median time of 51 days (7-1537), and six (18.3%) received interferon alfa (IFN), for a median time of 11 months (1-30 months). One patient received an autologous hematopoietic stem cell transplantation and after molecular relapse was treated with imatinib. The median duration of imatinib treatment was 9.5 years (3-16). One patient was transferred to another center after receiving the 3 months of pioglitazone, and was not analyzed for TFR and adverse events after imatinib discontinuation. The median follow-up of the 31 patients after imatinib discontinuation was 19 months (2-41 months). There were no grade 3-4 adverse events related to pioglitazone. Twelve out of 31 patients relapsed in a median time of 5 months (2-30 months). Most of the relapses (n = 9) occurred in the first 6 months, and three relapses occurred at 7, 13, and 30 months after stopping imatinib. There was no hematological relapse or progression to the accelerated phase or blast crisis. The TFR was 67%, 64% and 60% at 6, 12 and 30 months, respectively (Figure 1). The median follow-up was 19 months. There no statistical difference in TFR according to gender, previous IFN use or withdrawal syndrome (Figures S3A-C), but TFR was higher in low Sokal score patients and with longer duration of treatment (Figure S4A-C). Low Sokal score and MR4.5 duration were significant factors for prolonged TFR in the multivariate analysis (P = .032 and .008, respectively). All patients achieved a major molecular response after imatinib reintroduction, in a median time of 3 months (1.8-4.1) and MR4.0 in a median time of 3 months (1-10). Regarding safety, pioglitazone was well tolerated in the majority of the patients. One patient interrupted pioglitazone during the first month, and one required dose reduction to 30 mg in alternate days due to worsening of periorbital and limbs edema. There was an increase in weight variation before and after pioglitazone (mean weight = 83.7 kg (± 22 kg) vs 85.2 kg (± 21 kg), P = .003.There were no grades 3 or 4 adverse events. After imatinib discontinuation, there was no significant variation in weight (81 vs 83 kg; P = .89). There was an increase in hemoglobin (Hb) levels (baseline: mean 13.2 g/dL (±1.5); 3 months: 14.8 g/dL (±1.3); 6 months: 14.3 g/dL (±1.5), P = .07). Four patients had an increase in Hb levels above the normal range after discontinuation. During the first year of discontinuation, 15/31 (48%) patients presented a new or worsening musculoskeletal pain or arthralgia (grades 1-2), which could be attributed to withdrawal syndrome. Patients referred pain in shoulders, hips, lumbar region, legs, hands, and feet. Seven out of 31 patients (22.5%) presented grade two events, requiring analgesia with paracetamol, metamizol (dipyrone) or anti-inflammatory drugs. Two patients required steroids. There was no need to reinitiate imatinib due to this event. There were three patients with hyperglycemia and two patients with an increase in cholesterol levels or triglycerides. In the third year after discontinuation, a patient developed an anal canal adenocarcinoma and was treated with surgery and chemotherapy. Three out of 32 (9.3%) patients had altered creatinine at study entry (two had hypertension history, and one had no comorbidity). After imatinib discontinuation, creatinine levels decreased in two of them. We previously mentioned that the rationale for using pioglitazone was based on the initial findings of Prost et al., which showed a benefit for imatinib and pioglitazone in vitro and in vivo studies.2 The authors demonstrated a PPAR-gamma inhibition after 6 months. In our study, we chose to treat the patients for 3 months with pioglitazone because all of them had deep molecular response (MR4.5), and we did not want to increase toxicity. The phase II trial ACTIM reported an improvement of MR4.5 achievement in a group of 24 CML patients treated with imatinib and pioglitazone over 12 months, in comparison with a historical cohort treated only with imatinib (56% vs 23%).4 In both studies, the authors used pioglitazone with imatinib before the achievement of a deep molecular response. However, the benefit of this combination is complex and needs further evaluation. Wang et al. have demonstrated that in diagnostic CML mononuclear cells and BCR-ABL1+ cell lines, PPAR-gamma significantly decreases organic cation transporter-1 (OCT-1) activity.5 The authors suggest that the effect of PPAR-gamma activation on imatinib uptake in mononuclear cells may counteract the clinical benefit of this activation in stem cells, particularly in patients with high PPAR-gamma activity.6 Note, OCT-1 activity is a predictor of long term outcome in CML patients treated with imatinib.6 The authors suggest that the effect of PPAR-gamma activation on imatinib uptake in mononuclear cells may counteract the clinical benefit of this activation in stem cells, particularly in patients with high PPAR-gamma activity.5 In our study, the TFR rate at 12 months was consistent with other imatinib discontinuation trials, such as the Korean trial and A-STIM and slightly superior to TWISTER, probably due to differences in the imatinib reintroduction criteria.1 Treatment-free remission was estimated as 64% at 12 and 24 months, and 61% at 36 months in the A-STIM trial. In most studies, the criteria for imatinib reintroduction was the loss of MMR, except for TWISTER trial, in which molecular relapse was defined as any single sample with loss of MMR or two consecutive positive samples at any value, while in our study the criteria was loss of MMR or confirmed loss of MR4.0 (in two samples). All these studies have shown that the majority of relapses occurred in the first 6 months.1 In our trial, we observed the same pattern, although we had one late relapse at 30 months, which confirms previous reports that patients should maintain regular monitoring. In summary, our results showed that the combination of pioglitazone and imatinib was feasible and safe. However, we could not demonstrate if there is a benefit in TFR in this first analysis. The ongoing follow-up will allow the assessment of the long-term benefit of this combination on the TFR rate. A.B.P.L. is supported by Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) scholarship (88882.434900/2019-01). The authors would like to thank all the study participants, investigators and staff involved in patient care and laboratories from Hemocentro, Unicamp. Contribution: K.B.B.P., principal investigator of this trial, conceived and designed the study; E.V.D.P., M.T.D. and G.O.D. were sub-investigators. KBBP and EVDP contributed to the data interpretation and drafted the manuscript. K.B.B.P., E.V.D.P., A.B.P.L., E.C.M., C.D.S. contributed to critical review and revision of the manuscript. ECM made the statistical analysis. A.B.P.L., M.T.D., G.O.D., J.V., M.A.S.S. participated in the site work, including the recruitment, follow-up, and data collection. A.B.P.L., B.R.V.R., V.M.O.P. and G.C.P.F. performed laboratory analyses. All authors approved the final version of the final manuscript and were responsible for the decision to submit for publication. K.B.B.P., Advisory Board: Astellas, Abbvie, Novartis; Lectures: EMS, Pintpharma, Jansen, Astellas. The other authors declare no conflict of interest. The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions. Figure S1 EDI-PIO study design Figure S2. Patient flow chart for EDI-PIO trial Figure S3. TFR by Sokal score and duration of TKI treatment Figure S4. TFR by withdrawal syndrome, sex and IFN use Table S1. Patients' characteristics at diagnosis and study entry (n = 32) Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.