Abstracts Clinical Lymphoma, Myeloma & Leukemia September 2023 S362 a patient’s experience and quality of life. Noninvasive, point-of care Hb measurements might offer significant advantages for these patients, due to a potential reduction of visits and the empowerment of patients toward an active role in their journey, enabling healthcare providers to adjust treatments promptly to improve patient outcomes. Objective, Design and Methods: Within the non-interventional, prospective-exploratory HeMonitor study, we aimed to develop a noninvasive Hb level prediction model based on photographs of the ocular conjunctiva and fingernails using machine learning (ML). After ethics approval, we recruited two cohorts: 1) patients with hematological malignancies undergoing regular hemoglobin measurements (n=373); and 2) volunteer healthy blood donors (n=188). To generate the training and testing data set, we took photographs (ocular conjunctiva and fingernails) under laboratory conditions (calibrated Sony ILCE-7 camera, standardized light and setup) and gathered patient clinical data along with an invasively determined Hb level measured on the same day. We then trained a Bayesian Ridge Regression model using the SciKit-Learn Python framework with the laboratory-derived Hb measure as the target feature. Results: Based on the implemented approach, we report a mean Hb deviation of 1.32 mmol/L using photographs of conjunctiva and 1.62 mmol/L using photographs of fingernails compared to invasive hemoglobin measurement methods. Using photographs from conjunctiva in combination with fingernails in a sequential prediction pipeline, our models mean Hb deviation is 1.42 mmol/L. There was a lower accuracy in patients below the anemia threshold (7.4 mmol/L) with frequent deviations of 4 mmol/L. Conclusion: Within our proof-of-concept HeMonitor study, we have demonstrated that noninvasive Hb measurement is feasible. The main limitations of our results are lower accuracy in severely anemic patients, and thus, currently limited clinical applicability. Validation of our ML model is currently ongoing within a larger, prospective study. Overall, by providing a way to monitor Hb levels regularly at home, these measurements can contribute to better management of anemia and more personalized cancer care. Keywords: hemoglobin, machine learning, health-related quality of life, anemia, myelodysplastic neoplasms MDS-345 Nature of Clinical Response and Depth of Molecular Response in Patients With TP53‑Mutant Myelodysplastic Syndromes (MDS) and Acute Myeloid Leukemia (AML) Treated With Magrolimab With Azacitidine Lisa Johnson MBA, PhD1, Yajia Zhang PhD1, Biao Li PhD1, Lisa Aviles MBA, BS1, Naval G. Daver MD2, Paresh Vyas PhD3, David A. Sallman MD4 1Gilead Sciences Inc, Foster City, USA. 2The University of Texas MD Anderson Cancer Center, Houston, USA. 3Weatherall Institute of Molecular Medicine, Oxford, United Kingdom. 4Moffitt Cancer Center, University of South Florida, Tampa, USA Context: Magrolimab is a monoclonal anti-CD47 antibody that blocks tumor antiphagocytic signals. Azacitidine increases tumor cell prophagocytic signal expression, synergizing with magrolimab to facilitate phagocytosis. We report the somatic mutational landscape of a subset of patients with AML (n=23) or MDS (n=56) receiving magrolimab+azacitidine in a Phase I trial (NCT03248479) to identify prognostic mutations. Methods: Patients received escalating magrolimab doses (1−30 mg/kg) for 2 weeks, then maintenance at 30 mg/kg weekly or biweekly from Cycle (C) 3, plus azacitidine (75 mg/m2) on days (D) 1−7 of each 28-day cycle. Whole-exome sequencing was performed on samples from screening and posttreatment bone marrow aspirates from treatment-naive patients with Revised International Prognostic Scoring System (IPSS-R) higherrisk MDS and patients with AML ineligible for induction therapy. Processing pipelines combining algorithms with novel filtering, curation, and quality-control steps were developed using a variant allele frequency (VAF) cutoff=0.07. Results: At screening, TP53 was the most common variant (MDS: 8/51 [16%]; median [range] VAF, 0.38 [0.14−0.86]; AML: 22/35 [63%]; median [range] VAF, 0.37 [<0.07−0.88]). 63% of patients with MDS (5/8) and 59% of those with AML (13/22) had complex cytogenetics. TP53 biallelic loss (2 mutations, mutation+alt 17, or VAF >0.5) was observed in 5 patients with MDS and 17 with AML. In the MDS subgroup, complete remission (CR) and marrow CR (mCR) rates were 38% (3/8) and 13% (1/8) for TP53-mutated patients, and 30% (13/43) and 35% (15/43), respectively, for TP53 wild-type patients. All three TP53-mutated patients with CR had a TP53 VAF <0.07 by C5D1. In the AML group, CR rates for TP53-mutated and wildtype patients were 59% (13/22 patients, including 2 with CR with incomplete/partial hematologic recovery and 1 with morphologic leukemia-free status) and 46% (6/13), respectively. Among TP53mutated CR patients, TP53 VAF <0.07 was observed in 7/13 (54%) patients at C3D1, 9/12 (75%) at C5D1, and 3/5 (60%) at C7D1. Similar CR rates (MDS, 20%−50%; AML, 33%−100%) were observed in patients with non-TP53 mutations, generally with lesser VAF decreases. Conclusion: Magrolimab reduced TP53 mutation allele frequency as early as C3 in patients with MDS/AML receiving magrolimab+azacitidine, potentially altering the disease course of TP53-mutated malignancies. Funding: Gilead Sciences, Inc. Keywords: MDN, magrolimab, azacitidine, acute myeloid leukemia, myelodysplastic syndromes, anti-CD47 MDS-350 Prognostic Impact of Lymphopenia in Myelodysplastic Neoplasms (MDS) David Fandrei MD candidate, MSc candidate1,2,3, Nicolas Dulphy MD, PhD1, Karl Balabanian PhD1, Marion Espéli PhD1, Marie Sérbert MD, PhD2, Pierre Fenaux MD, PhD2, Lionel Adès MD, PhD2, Lin-Pierre Zhao MD, PhD1,2 1INSERM U1160, Institut de Recherche Saint Louis, Paris, France. 2Université de Paris, Department of Hematology, Hôpital Saint-Louis, Assistance Publique des Hôpitaux de Paris (AP-HP), Paris, France. 3Gustave Roussy, PRISM, Paris, France Context: Dysregulation of innate and adaptive immunity in myelodysplastic neoplasms (MDS) suggest that host immunity has a
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