High-Risk Subtype of Ph-like Acute Lymphoblastic Leukemia (ALL) in Adults: Dismal Outcomes of CRLF2+ ALL Patients Treated with Intensive Chemotherapy
Authors: Jain Nitin , Roberts Kathryn G. , Jabbour Elias J. , Patel Keyur , Eterovic Karina , Fawcett Gloria , Zweidler-McKay Patrick , Lu Xinyan , Wang Sa , Konoplev Sergej , Harvey Richard C , Chen I-Ming L. , Payne-Turner Debbie , Valentine Marcus , Thomas Deborah A , Garcia-Manero Guillermo , Ravandi Farhad , Cortes Jorge E. , Kornblau Steven M. , O'Brien Susan M. , Pierce Sherry , Jorgensen Jeffrey L. , Shaw Kenna , Willman Cheryl L. , Mullighan Charles , Kantarjian Hagop M. , Konopleva Marina 
Published: October 2019

Abstract
Background:Ph-like acute lymphoblastic leukemia (ALL) is a high-risk subtype of ALL in children. There are limited and conflicted data on the incidence and prognosis of Ph-like ALL in adults.
Methods:Patients with newly-diagnosed B-ALL who received frontline chemotherapy at MD Anderson Cancer Center underwent gene expression profiling of leukemic cells to identify Ph-like ALL. Gene expression profiling was performed on 148 RNA samples using either U133 Plus 2.0 microarrays, or a customized Taqman low density array (LDA) card to identify patients with the Ph-like ALL gene signature (Roberts et al. NEJM 2014). An additional 7 previously untreated patients were found to have CRLF2 overexpression by multicolor flow-cytometry (MFC), and received induction chemotherapy at MDACC were included in the outcome analysis (but not for subtype frequency calculation). We performed targeted sequencing of 303 recurrently mutated genes (L300 panel, MDACC) in 40 patients with CRFL2 rearrangements (15 with matched germline control). Minimal residual disease (MRD) was assessed by MFC, with a sensitivity of 0.01%.
Results:Of 148 patients, 49 (33.1%) were Ph-like, 46 patients (31.1%) were Ph+, and 53 patients (35.8%) were of other B-ALL subtypes (B-other). The median age of Ph-like cohort was 33.5 years (range, 15-71), Ph+ cohort was 49 years (range, 22-84), and B-other was 38 years (range, 15-79). Within the Ph-like ALL cohort, 61% had overexpression of CRLF2. Patients received hyper-CVAD (80%) or an augmented-BFM regimen (20%). The rate of CR/CRp was similar in the 3 disease subgroups (Ph-like ALL 89%, Ph+ ALL 93%, B-other 94%, p = 0.57). However, patients with Ph-like ALL were significantly less likely to achieve MRD-negative remission (30% vs. 56% for Ph+ ALL vs. 87% for B-other, p <0.001). Patients with Ph-like ALL had significantly worse overall survival (OS) and event-free survival (EFS) compared to B-other with a 5-year survival of 23% (vs. 59% for B-other, p=0.006) (Figure 1A). The poor outcomes of Ph-like ALL were also observed when only hyper-CVAD treated patients were considered. Interestingly, 68% of the patients with Ph-like ALL (78% among the CRLF2+ cohort) were of Hispanic ethnicity. This was significantly higher compared to Ph+ ALL (35%) and B-other (30%), p <0.001. Patients with CRLF2 overexpression had significantly inferior OS, EFS, and remission duration when compared to other genomic subgroups, including the Ph-like non-CRLF2 group (Figure 1B). Notably, 5-year survival in the CRLF2+ group was <20%. The following were independently associated with inferior OS on multivariable analysis: age (hazard ratio [HR] 2.474, p<0.001); WBC count (HR 1.183, p=0.007); platelet count (HR 4.283, p<0.001) and Ph-like ALL (HR 1.579, p=0.04) (Table 1).
The most common mutations by L300 sequencing of 40 patients with CRLF2 were JAK2 (n=19, 47.5%), KRAS (n=10, 25%), CRLF2 (n=7, 17.5%), NRAS (n=5, 12.5%), PAX5 (n=5, 12.5%), JAK1 (n=4, 10%) (Figure 2). The CRLF2 F232C mutation, noted in 7 (17.5%) patients in this study, appears more frequent than in pediatric patients (3/134, 2.2%, Chen et al. Blood 2012), and in range with a smaller adult series (3/14, 21.4%, Yoda et al. PNAS 2010). CRLF2 F232C mutations were mutually exclusive with JAK2/JAK1 mutations (except in one patient).
Conclusions:Our findings show a high frequency of Ph-like ALL in adults; an increased frequency of Ph-like ALL in adults with Hispanic ethnicity; significantly inferior outcomes of adult patients with Ph-like ALL; and significantly worse outcomes in Ph-like ALL patients with CRLF2 overexpression. The frequency of CRLF2 F232C mutation appears to be higher in adult patients with B-ALL than in the children. Ph-like ALL represents a high-risk disease subtype of adult B-ALL. Novel strategies are needed to improve the outcome of these patients.

Disclosures
Jain: Pharmacyclics: Consultancy, Honoraria, Research Funding; Genentech: Research Funding; Incyte: Research Funding; BMS: Research Funding; Abbvie: Research Funding; Pfizer: Consultancy, Honoraria, Research Funding; Celgene: Research Funding; ADC Therapeutics: Consultancy, Honoraria, Research Funding; Seattle Genetics: Research Funding; Servier: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Infinity: Research Funding; Novimmune: Consultancy, Honoraria. Jabbour:ARIAD: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; Novartis: Research Funding; BMS: Consultancy. Cortes:ARIAD: Consultancy, Research Funding; BMS: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; Teva: Research Funding. O'Brien:Pharmacyclics, LLC, an AbbVie Company: Consultancy, Honoraria, Research Funding; Janssen: Consultancy, Honoraria. Mullighan:Incyte: Membership on an entity's Board of Directors or advisory committees; Amgen: Speakers Bureau; Loxo Oncology: Research Funding. Konopleva:Reata Pharmaceuticals: Equity Ownership; Abbvie: Consultancy, Research Funding; Genentech: Consultancy, Research Funding; Stemline: Consultancy, Research Funding; Eli Lilly: Research Funding; Cellectis: Research Funding; Calithera: Research Funding.