Peripheral Blood Complete Remission Provides Added Value to the Classical Definition of Morphologic Complete Remission - a Prospective Cohort Study of 1441 Patients with MDS, CMML and AML Treated within the Austrian Azacitidine Registry
Authors: Pleyer Lisa , Pfeilstocker Michael , Stauder Reinhard , Heibl Sonja , Sill Heinz , Girschikofsky Michael , Stampfl-Mattesberger Margarete , Tinchon Christoph , Hartmann Bernd , Petzer Andreas , Petricevic Branka , Schmitt Clemens A. , Vallet Sonja , Geissler Klaus , Sperr Wolfgang R. , Leisch Michael , Egle Alexander , Melchardt Thomas , Piringer Gudrun , Zebisch Armin , Machherndl-Spandl Sigrid , Wolf Dominik , Keil Felix , Angermann Hubert , Drost Manuel , Larcher-Senn Julian , Greil Richard 
Published: November 2021

Abstract
Background In myelodysplastic syndromes (MDS), chronic myelomonocytic leukemia (CMML) and acute myeloid leukemia (AML) achievement of complete remission (CR) is a prerequisite for potential cure. In AML, CR/CR with incomplete recovery (CRi) is deemed the major outcome associated with improved overall survival (OS); patients (pts) without CR/CRi are considered non-responders, and hematologic improvement (HI) without (assessment of) bone marrow (BM) blast clearance is considered treatment (trt) failure. Achievement of CR may not be necessary for prolonged OS in pts treated with azacitidine (AZA) (Pleyer L, Annals Hematol 2014, 1825; Schuh AC, ASH 2015, P575).
Outside of clinical trials, BM evaluations (BME) are only performed in ~50% of pts (Dinmohamed, Leuk Res 2015, 177) when either response or progression are obvious from peripheral blood (PB) values, or when pts are unable or unwilling to have BME.
Aims To assess of the impact of response type on AZA trt outcomes in multivariate adjusted analyses (MVA).
Methods 1441 pts included in the Austrian Azacitidine Registry were analyzed (NCT01595295). Data cut-off was 1 July 21. Marrow response was assessed for MDS/CMML and AML at each BME; HI was assessed on day 1 of each AZA cycle (Döhner H, Blood 2017, 424; Cheson BD, Blood 2006, 419; Pleyer L, ASH 2019, P3821); peripheral blood complete remission (PB-CR) was defined as hemoglobin ³11 g/dL, platelet count ≥100 G/L, neutrophil count ³1.0 G/L, white blood cell count &lt;15 G/L, PB blasts =0%, and no transfusions. Response types were calculated from electronic case report form data. To identify which response type achieved by which AZA cycle had the highest impact on time-to-event endpoints, likelihood ratios (LR) of the Cox-regression model for OS or time to next treatment (TTNT) were calculated using the respective response types as covariates. Baseline characteristics with univariate p&lt;0·10 (n=23) for association with OS were included in the multivariate regression. After stepwise selection n=17 variables remained and were used for MVA. Assign Data Management and Biostatistics GmbH performed statistical analyses with SAS® 9.4.
Results In total, 521, 135, and 785 pts had MDS, CMML and AML. Median year of initial diagnosis was 2012, median time to AZA start was 3·0 (IQR 1·0-13·2) months (mo), median follow-up time from AZA start was 10.6 (IQR 4·0-21·1) mo, 894 pts received AZA as first line trt, median age at AZA start was 73 (range 23-99) years. In total, 13956 AZA cycles were applied, median duration of AZA trt was 5·0 (IQR 1·9-12·1) mo, median AZA dose was 875 (IQR 700-1000) mg/cycle, AZA was applied for a median of 7 (IQR 5-7) days.
Median time to best response was 3·7 (IQR 2·0-5·9) months. Early mortality was 5.5% within 30 days. During AZA trt 1225 BM evaluations (BME) were performed in 697 (48·4%) of pts. Of these, 204 achieved CR/CRi. Irrespective of BME, 622 (43%) of 1441 pts achieved an HI and 264 (18·3%) of 1441 pts achieved a PB-CR.
Pts achieving CR had longer adjusted OS (23·7 vs 19·7 mo, p=0·0227; HR=0·621 [0·413-0·936]) and TTNT (19·4 vs 15·7 mo, p=0·0262; HR=0·644 [0·436-0·949]) than pts achieving CRi.
Among pts achieving CR, those additionally achieving PB-CR had longer adjusted OS (24·8 vs 16·3; p=0·0040; HR=0·256 [0·101-0·647]; Fig 1A) and TTNT (21·2 vs 11·0; p=0·0005; HR=0·219 [0·094-0·513]; Fig 1B) than those who did not. Among pts not achieving CR, those additionally achieving PB-CR had longer adjusted OS (20·8 vs 14·1; p&lt;0·0001; HR=0·510 [0·397-0·657]; Fig 1A) and TTNT (17·7 vs 10·9; p&lt;0·0001; HR=0·485 [0·357-0·589]; Fig 1B) than those who did not.
Among all pts, irrespective of BM blast count, achievement of PB-CR resulted in longer adjusted OS (21·7 vs 10·0 mo; p&lt;·0001; HR 0·363; Fig 1C) and TTNT (18.5 vs 7.8 mo; p&lt;0.0001; HR=0.346; Fig 1D) and provided added value to CR and CR/CRi.
Among all response types and after MVA, the highest prognostic impact on both OS and TTNT was observed when achieving PB-CR or CR/CRi by cycle 9 or 10 (Fig 2A-B).
Conclusions Above data indicate that achievement of PB-CR is a strong predictor of OS and TTNT that provides additional information to current response criteria. Inclusion of PB-CR in updated response criteria of pts with MDS, CMML or AML receiving non-intensive trt should be considered. The greatest advantage of PB-CR is that it can be easily, nearly painlessly and quickly assessed. Inclusion of PB-CR as an endpoint in clinical trials would be desirable for validation of these results.
Figure 1 Figure 1.

Disclosures
Pleyer: AbbVie, BMS, Novartis: Honoraria, Other: Travel Sport. Pfeilstocker: BMS: Honoraria. Stauder: Celgene/BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel support; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees. Heibl: BMS: Honoraria. Sill: Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees; Astellas: Consultancy, Membership on an entity's Board of Directors or advisory committees; AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees. Hartmann: Celgene, Amgene, Janssen, AbbVie: Honoraria. Petzer: Kite-Gilead: Honoraria, Membership on an entity's Board of Directors or advisory committees; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees; Abbvie: Honoraria, Membership on an entity's Board of Directors or advisory committees; Astra Zeneca: Honoraria, Membership on an entity's Board of Directors or advisory committees; Sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees; Saegen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Daiichi Sankyo: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Sandoz: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene-BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees. Geissler: BMS: Honoraria. Sperr: AbbVie, BMS-Celgene, Daiichi Sankyo, Deciphera, Incyte, Jazz, Novartis, Pfizer, StemLine, Thermo Fisher: Honoraria, Research Funding. Leisch: Honoraria from BMS, Celgene, Gilead, Takeda and Novartis; Travel support: Celgene and Novartis: Honoraria, Other: Travel support. Melchardt: Abbvie, Celgene, Novartis: Honoraria. Zebisch: Novartis: Consultancy; AbbVie: Consultancy; Celgene: Consultancy, Honoraria. Machherndl-Spandl: AbbVie, Celgene, BMS, Pfizer: Honoraria. Wolf: Roche: Honoraria, Research Funding; MSD: Honoraria, Research Funding; BMS-Celgene: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; Pfizer: Honoraria, Research Funding; Takeda: Honoraria; Gilead: Honoraria; Incyte: Honoraria; GEMOAB: Honoraria. Greil: Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses, Research Funding; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses, Research Funding; Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses, Research Funding; BMS: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses, Research Funding; Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses, Research Funding; AstraZeneca: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses, Research Funding; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses; MSD: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses, Research Funding; Gilead: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses, Research Funding; Daiichi: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses, Research Funding; Sankyo: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses, Research Funding; Sanofi: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Merck: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Honoraria, Other: Travel, Accommodations, Expenses, Research Funding; Sandoz: Honoraria, Research Funding.

OffLabel Disclosure:
Azacitidine is approved for all types of MDS and CMML as well as low blast count AML by FDA, but not for all subtypes of MDS and CMML by EMA.