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3955 Outcomes of Allogeneic Hematopoietic Cell Transplantation in Adults with Ph-like ALL

Program: Oral and Poster Abstracts
Session: 732. Allogeneic Transplantation: Disease Response and Comparative Treatment Studies: Poster III
Hematology Disease Topics & Pathways:
Biological therapies, Workforce, Therapies, Technology and Procedures, Transplantation, Pathology
Monday, December 13, 2021, 6:00 PM-8:00 PM

Ibrahim Aldoss, MD1, Dongyun Yang, PhD2*, Zhaohui Gu, PhD2, Vanina Tomazian3*, Sally Mokhtari4, Ryan Jackson3*, Milhan Telatar, PhD3*, Hooi Yew, PhD3*, MHD Monzr M. Al Malki, MD5, Amandeep Salhotra, MD1, Samer Khaled6*, Haris Ali, MD1, Ahmed Aribi, MD1, Karamjeet S. Sandhu, MD 1, Matthew Mei, MD1, Shukaib Arslan, MD1, Paul Koller, MD1, Andrew S. Artz, MD, MS5, Patricia Aoun, MD1*, Dongqing Gu3*, David S Snyder, MD1, F. Mark Stewart, MD1*, Peter T. Curtin, MD1, Anthony S. Stein, MD1, Raju Pillai, MD3*, Guido Marcucci, MD1, Stephen J Forman, MD1, Vinod A. Pullarkat, MD1, Ryotaro Nakamura, MD1 and Michelle Afkhami, MD3*

1Department of Hematology/HCT, City of Hope National Medical Center, Duarte, CA
2Department of Computational and Quantitative Medicine, City of Hope National Medical Center, Duarte, CA
3Department of Pathology, City of Hope National Medical Center, Duarte, CA
4Department of Clinical Translational Program Development, City of Hope National Medical Center, Duarte, CA
5Department of Hematology/HCT, City of Hope, Duarte, CA
6Janssen Research & Development, Los Angeles, CA

Philadelphia chromosome-like acute lymphoblastic leukemia (Ph-like ALL) represents 20% of newly diagnosed adults with B cell ALL (B-ALL), with increased frequency in adults with Hispanic ethnicity. Ph-like ALL harbors a diverse range of genetic alterations with CRLF2-rearrangement/overexpression (CRLF2r) being the most common one. When treated with chemotherapy, Ph-like ALL is associated with inferior response, high relapse rate, and low overall survival (OS). Allogenic hematopoietic cell transplantation (alloHCT) is a well-established curative modality for adults with high-risk ALL. Considering that Ph-like ALL is a high-risk leukemia subtype, it is appealing to recommend alloHCT consolidation routinely for this entity in adults. However, large datasets describing alloHCT outcomes in patients with Ph-like ALL is lacking.

In this study, we retrospectively analyzed archived DNA samples from 125 consecutive adult patients with Ph-negative ALL who underwent alloHCT in complete remission (CR) at our center between 2006 and 2020. Classification of Ph-like versus non-Ph-like was performed according to WHO 2017 classification using accumulative results from RNAseq, conventional cytogenetics, FISH, and whole genome array studies. A proprietary RNA sequencing assay covering 1,188 genomic regions from 235 genes was designed to detect all the clinically significant fusions and expressions for Ph-like ALLs. In addition, an algorithm employing the RNAseq data was developed to further aid in classification of Ph-like ALL.

Boruta feature selection (R package “Boruta” version 7.0.0) was used to identify the most informative genes for prediction with an out-of-bag error of 9.62%. The following 24 genes were identified: CCND2, SOX11, PAX5, DENND3, RARA, MME, ID4, SH3BP5, HOXA9, CA6, MUC4, CYB5R2, CD97, EPOR, IL2RA, RAB29, PDGFRA, MLLT4, RHOA, JAK2, DNM2, ASXL1, BCL2A1, and KDR. The results were used to predict Ph-like status by a Random Forest model (R package “randomForest” version 4.6-14) that generates a probability/similarity score of Ph gene expression profile (Ph score). The testing samples with Ph score over 50% and without other subtype-defining lesions are defined as Ph-like.

We identified Ph-like genetic alterations in 66 (53%) patients, of whom 42 (66%) were carrying CRLF2r and 24 (36%) were non-CRLF2r. Compared to non-Ph-like ALL (n=59), Ph-like ALL patients were younger (42 vs 36 years old, p=0.022), more frequently Hispanic (56% vs 83%, p=0.003), less frequently carried high-risk cytogenetics (39% vs 9%, p<0.001), more frequently induced with pediatric-inspired regimens (25% vs 61%, p=0.003) and more likely required >1 regimen to achieve their first complete remission (CR1; 30% vs 55%, p=0.025). However, we did not detect any significant difference between the two groups in disease status (CR1 vs. CD2/3; p=0.81) or minimal residual disease clearance at the time of HCT (negative vs. positive; p=0.17), donor type (match related/unrelated vs mismatch vs haplo vs cord blood; p=0.88), conditioning regimen intensity (myeloablative vs non-myeloablative/ reduced intensity; p=0.59), GVHD prophylaxis (tacrolimus/sirolimus-based vs PTCy-based; p=0.84), Karnofsky Performance Status (KPS; p=0.24) or HCT comorbidity index (0 vs 1-2 vs >2; p=0.42).

With the median follow-up of 3.2 years, we observed similar 3-years leukemia-free survival (LFS) (40% vs 47%; p=0.95), OS (44% vs 54%; p=0.96), relapse rate (33% vs 34%; p=0.96) and non-relapse mortality (NRM) (27% vs 19%; p=0.92) between non-Ph-like and Ph-like ALL patients, respectively. (Figure) In multivariable analysis, disease status at the time of HCT (HR=2.63, 95% CI: 1.57-4.41; p<0.001), donor type (p=0.049) and KPS (HR=2.22, 95% CI: 1.05-4.69; p=0.038) influenced OS. LFS was significantly influenced by disease status (HR=2.35, 95% CI: 1.45-3.80); p<0.001) and conditioning regimen intensity (HR=1.84, 95% CI: 1.11-3.04; p=0.017). Relapse rate was associated with disease status (HR=2.06, 95%CI: 1.11-3.84; p=0.23) and conditioning regimen intensity (HR=1.97, 95% CI: 1.03-3.75; p=0.40). Only KPS (HR=6.56, 95% CI: 2.48-17.36; P<0.001) was associated with NRM.

In conclusion, our data suggest that alloHCT consolidation results in favorable outcomes in adult patients with Ph-like ALL with comparable outcomes to non-Ph-like ALL. Our data support utilization of alloHCT for adults with Ph-like ALL in CR.

Disclosures: Al Malki: Neximmune: Consultancy; Rigel Pharma: Consultancy; Jazz Pharmaceuticals, Inc.: Consultancy; Hansa Biopharma: Consultancy; CareDx: Consultancy. Khaled: Omeros: Honoraria; Alexion: Honoraria, Speakers Bureau; Janssen: Current Employment; Astellas: Honoraria; Jazz: Honoraria. Ali: Incyte: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; BMS: Speakers Bureau; CTI BioPharma: Membership on an entity's Board of Directors or advisory committees. Aribi: Seagen: Consultancy. Mei: BMS: Research Funding; Epizyme: Research Funding; TG Therapeutics: Research Funding; EUSA: Honoraria; Janssen: Honoraria; Morphosys: Research Funding; Beigene: Research Funding. Koller: Novartis: Consultancy. Artz: Radiology Partners: Other: Spouse has equity interest in Radiology Partners, a private radiology physician practice. Stein: Amgen: Consultancy, Speakers Bureau; Celgene: Speakers Bureau; Stemline: Speakers Bureau. Marcucci: Abbvie: Other: Speaker and advisory scientific board meetings; Novartis: Other: Speaker and advisory scientific board meetings; Agios: Other: Speaker and advisory scientific board meetings. Forman: Lixte Biotechnology: Consultancy, Current holder of individual stocks in a privately-held company; Mustang Bio: Consultancy, Current holder of individual stocks in a privately-held company; Allogene: Consultancy. Pullarkat: AbbVie, Amgen, Genentech, Jazz Pharmaceuticals, Novartis, Pfizer, and Servier: Membership on an entity's Board of Directors or advisory committees; Amgen, Dova, and Novartis: Consultancy, Honoraria.

*signifies non-member of ASH