<scp><i>TP53</i></scp> disruption as a risk factor in the era of targeted therapies: A multicenter retrospective study of 525 chronic lymphocytic leukemia cases
Authors: Fortunato Morabito, Giovanni Del Poeta, Francesca Romana Mauro, Gianluigi Reda, Paolo Sportoletti, Luca Laurenti, Marta Coscia, Yair Herishanu, Sabrina Bossio, Marzia Varettoni, Roberta Murru, Annalisa Chiarenza, Andrea Visentin, Adalgisa Condoluci, Riccardo Moia, Daniela Pietrasanta, Giacomo Loseto, Ugo Consoli, Ilaria Scortechini, Anna Grazia Recchia, Francesca Maria Rossi, Antonella Zucchetto, Hamdi Al‐Janazreh, Enrica Antonia Martino, Ernesto Vigna, Giovanni Tripepi, Graziella D'Arrigo, Sara Galimberti, Angela Rago, Ilaria Angeletti, Annalisa Biagi, Ilaria Del Giudice, Riccardo Bomben, Antonino Neri, Gilberto Fronza, Giovanna Cutrona, Ozren Jaksic, Jacopo Olivieri, Davide Rossi, Francesco Di Raimondo, Antonio Cuneo, Gianluca Gaidano, Aaron Polliack, Livio Trentin, Robin Foà, Manlio Ferrarini, Valter Gattei, Massimo Gentile
Journal: American Journal of Hematology (2021)

The addition of the anti-CD20 monoclonal antibody (mAb) to fludarabine-cyclophosphamide or bendamustine has led to a remarkable improvement in both progression-free (PFS) and overall survival (OS) of young and elderly CLL patients with favorable prognostic markers.1 However, chemoimmunotherapy (CIT) is ineffective in cases with TP53 gene disruption, that is, the deletion of the short arm of chromosome 17 [del(17p)] and/or TP53 mutations (TP53mut).2 Ibrutinib (IB) and idelalisib (IDELA), which inhibit the signaling pathway initiated by the B-cell antigen receptor (BCR), or venetoclax (VEN), which facilitates cell apoptosis, have contributed to overcoming the modest efficacy of CIT in patients with del(17p) and/or TP53mut.3 However, these patients' treatment still represents a challenge, particularly for long-term leukemia control.4 Recently, an evaluation of the potential risk factors for OS has been carried out in a pooled, retrospective cohort of a considerable number of RR CLL patients treated with either CIT or with IB, IDELA-R, or VEN in the randomized phase 3 trials.5 The derived BALL score was based on four accessible markers, that is, β2-microglobulin (β2-M) and lactic dehydrogenase (LDH) serum levels, anemia, and time from the start of the last therapy. The BALL score, recently refined for IB or IDELA,6, 7 proved capable of prognostically segregating RR CLL patients. Notably, del(17p) failed to be classified as a risk factor for OS in this context, although TP53 inactivation was determined only by measuring del(17p), while the presence of TP53mut was not assessed. Therefore, TP53 disruption may have gone undetected, rendering the interpretation of the data somewhat complex. Recently, a four-factor model, capable of identifying patients at increased risk of IB failure, was proposed and included TP53 dysfunction measured by FISH and molecular analysis.8 The above prognostic model was validated in a real-world cohort.9 The present independent, retrospective, multicenter analysis of patients treated with IB (432 cases), IDELA (85), or VEN (eight cases) in the current clinical practice aimed to assess the value of the prognostic parameters set in previous studies and investigate the extent of TP53 disruption required to confer a dismal prognosis despite treatment with the new drugs. Table S1 summarizes the main patients' features. The majority of cases were Binet B and C (89.5%), 65.5% were male (65.5%), and the median age was 70.8 years (37.2–88.7). The median range of previous therapies was two (range 1–9). The TP53 dysfunction in our cohort was detected in 201 cases (38.3%). One hundred and fourteen patients died since starting the new therapies after a median follow-up of 1.7 years. Initially, Cox univariate analysis was used to evaluate the relationships of some predictors and OS. Note, β2-M, LDH levels, anemia, time from the start of the last therapy, Binet stage, and the number of previous treatments were found to be associated with OS (Table S2). Moreover, a significantly shorter OS was observed for cases carrying del(17p) (hazard ratio [HR] = 1.5, 95% CI 1.1–2.3, p = .024) or TP53mut (HR = 1.5, 95% CI 1.1–2.1, p = .049) (Figure 1(A), (B) and Table S2). To assess the independent relationship between TP53 disruption and OS, we constructed different Cox multivariate models in which either del(17p) (model 1) or TP53mut (model 2) were introduced (Table S3). Notably, while del(17p) showed an independent relationship with OS (Table S3 model 1), TP53mut failed to represent a significant independent risk factor (Table S3 model 2). Therefore, for a more precise risk assessment, CLL patients were stratified into four groups, which included cases with TP53wt/no-del(17p) (324, 61.7%), TP53mut/del(17p) (90, 17.1%), TP53mut/no-del(17p) (62, 11.8%), and TP53wt/del(17p) (49, 9.3%). The OS was significantly shorter in TP53mut/del(17p) cases (HR = 1.8, 95% CI 1.2–2.8, p = .004), while the Kaplan–Meier curves of both the TP53mut/no-del(17p) (HR = 0.9, 95% CI 0.4–1.7, p = .7) and of the TP53wt/del(17p) (HR = 0.8, 95% CI 0.4–1.6, p = .5) group overlapped with that of the TP53wt/no-del(17p) group (Figure 1(C)). Overall, these data demonstrated that simultaneous investigation of both del(17p) and TP53 led to a more accurate prognostic stratification of patients with both lesions compared with those with a single lesion or no lesions. A sub-analysis of the IB patients' cohort showed similar results (Figure S1). The simultaneous presence of TP53mut and del(17p) were subsequently introduced into a further Cox multivariate analysis (Table S3 model 3). The TP53mut/del(17p), remained independently related with OS (HR = 1.6, 95% CI 1.1–2.5, p = .026), together with LDH (HR = 1.6 95% CI 1.1–2.4, p = .013), anemia (HR = 2.5, 95% CI 1.6–3.9, p < .001), and previous therapy lines (HR = 2.0, 95% CI 1.2–3.2, p = .004). Finally, facing the different models in which TP53 alterations were differently defined, that is, as del(17p) alone (Table S3 model 1) and del(17p)/TP53mut (Table S3 model 3), the Akaike information criterion (AIC) weights indicated that model 3 had a 54% chance to be the best prognostic model for OS, thus supporting the concept that TP53mut or del(17p) should not be considered alternative markers but used in parallel to obtain a more precise prognostic evaluation. However, a limitation of our study is represented by the retrospective nature of TP53mut and del(17p) evaluations. A further weakness is represented by the low number of cases treated with VEN. Confirmation studies incorporating a significantly higher number of patients treated with VEN are warranted to confirm these findings. Regrettably, data on CK were available in 32.8% (172/525) of cases in our cohort. Thus, CK analysis presents some constraints due to its limited availability in the real-world setting, possibly due to laboratory hitches and the tendency to evaluate cytogenetic, mainly in research centers. However, given the similarities between the cohort with CK data available and the remaining CLL cohort (Table S4), including a similar prognostic impact of the TP53mut/del(17p) genotype combinations (Figure S2), we found of interest to explore the prognostic significance of CK as in association with TP53 disruption. Note, CK was detected in 19.7% (34/172) of patients, and it was associated with a significantly higher death risk (HR = 2.6; 95% CI 1.2–5.4, p = .012). The relationship between del(17p), TP53mut, and CK is described in Table S5. Among the 172 cases, 11 patients (6.4%) showed a triple alteration, while 10 (5.8%) cases showed a CK without any TP53 aberration. Moreover, nine (2.3%) and four (2.3%) cases presented CK associated with del(17p) and TP53mut only, respectively. Overall, CK was significantly linked with del(17p) (20/44 vs. 14/128, p < .001) and TP53mut (15/47 vs. 19/125, p = .05). Subjects with both a del(17p)/TP53mut genotype and CK experienced a significantly higher risk of death (HR = 5.5; 95% CI 1.98–15.4, p = .001) compared with triple-negative cases (i.e., devoid of CK and del(17p) and TP53mut) here combined with cases without CK but bearing del(17p) or TP53mut only (Figure S3). In contrast, the remaining groups comprising the single CK (ie, CK without TP53 disruption) as well as CK combined with the del(17p)/TP53WT category and the no-del(17p)/TP53mut category failed to show any prognostic power in this analysis (Figure S3). Notably, cases bearing the del(17p)/TP53mut genotype without CK aberration also showed a higher risk of death, of borderline significance compared to the control group (HR = 2.8; 95% CI 0.99–7.7, p = .052) (Figure S3). With the limitation of the relatively low number of cases analyzed, the above-described results indicated that CLL patients with a CK experienced a shorter OS than those free of the cytogenetic aberration. However, the prognosis of CK seems to be dependent on a complete TP53 alteration. Indeed, cases with both a del(17p)/TP53mut genotype and CK have a significantly higher death risk than triple-negative cases, assuming that TP53/del(17p) alterations may have extra prognostic value in patients with CK. Nevertheless, these conclusions should be considered with caution and deserve further investigation. In conclusion, this retrospective, multicenter study indicates the prognostic relevance of TP53 disruption assessment in patients with RR CLL undergoing treatment with the new molecularly targeted therapies. This assessment is best achieved when both TP53 mutations and del(17p) are measured, implying that the evaluation of a severe TP53 impairment allegedly involving both alleles is necessary for the setting of RR CLL treated with new drugs. Associazione Italiana Ricerca sul Cancro (AIRC) Grant 5 × mille n.9980, (to F.M.) and n. 21198, (to R.F); AIRC and Fondazione CaRiCal co-financed Multi-Unit Regional Grant 2014 n.16695 (to F.M.) Associazione Italiana Ricerca Cancro (AIRC), Investigator Grant IG-21687 (to V.G.) IG-5506 (to G.F.); Ricerca Finalizzata PE 2016-02362756, Ministero della Salute, Rome, Italy (to V.G.); Progetto Ricerca Finalizzata RF-2018-12365790, Ministero della Salute, Rome, Italy (to A.Z. and G.G.); Compagnia S. Paolo, Turin, Italy (Project 2017.0526 to G.F.) and by the Ministry of Health (Project 5 × 1000, 2015 and 2016 and Current Research 2016 to G.F.). AIRC 5 × 1000 No. 21198, Associazione Italiana per la Ricerca sul Cancro Foundation Milan, Italy (to R.F. and G.G.); Swiss Cancer League, ID 3746, 4395 4660, and 4705, Bern, Switzerland; European Research Council (ERC) Consolidator Grant CLLCLONE, ID: 772051; Swiss National Science Foundation, ID 320030_169670/1 and 310030_192439, Berne, Switzerland; The Leukemia & Lymphoma Society, Translational Research Program, ID 6594-20, New York. Funding of the project was also provided by an unrestricted contribution from GILEAD Sciences Srl. The funding sources had no role in identifying statements, abstracting data, synthesizing results, grading evidence or preparing the manuscript, or in the decision to submit the manuscript for publication (ISR-17-10250). The authors declare no conflict of interest. Fortunato Morabito, Giovanni Del Poeta, Francesca Romana Mauro, Anna Grazia Recchia, Adalgisa Condoluci, Sara Galimberti, Davide Rossi, Francesco Di Raimondo, Antonio Cuneo, Gianluca Gaidano, Aaron Polliack, Livio Trentin, Robin Foà, Manlio Ferrarini, Valter Gattei and Massimo Gentile designed the study, analyzed and interpreted data, and wrote the manuscript; Fortunato Morabito, Giovanni Tripepi, Graziella D'Arrigo, and Massimo Gentile performed statistical analysis; Anna Grazia Recchia, Antonella Zucchetto, Ilaria Del Giudice, Riccardo Bomben, Antonino Neri, Gilberto Fronza, and Giovanna Cutrona performed laboratory tests; Gianluigi Reda, Paolo Sportoletti, Luca Laurenti, Marta Coscia, Yair Herishanu, Marzia Varettoni, Roberta Murru, Annalisa Chiarenza, Adalgisa Condoluci, Riccardo Moia, Daniela Pietrasanta, Giacomo Loseto, Ugo Consoli, Ilaria Scortechini, Francesca Maria Rossi, V.F., Hamdi Al-Janazreh, Jacopo Olivieri, Ernesto Vigna, Angela Rago, Ilaria Angeletti, Andrea Visentin, and Annalisa Biagi provided the patients and collected clinical data. All authors gave final approval for the manuscript. The data that support the findings of this study are available from the corresponding author upon reasonable request Figure S1. Overall survival stratified according to del(17p) and/or TP53 mutation in CLL subgroups treated with ibrutinib in a real-world setting. Figure S2. Overall survival stratified by TP53 mutational status and del(17p) in the 172 patients with complex karyotype available treated with ibrutinib or idelalisib plus rituximab or venetoclax in a real-world setting. Figure S3. Overall survival stratified by TP53 mutational status, del(17p), and complex karyotype in the 172 patients treated with ibrutinib or idelalisib plus rituximab or venetoclax in a real-world setting with complex karyotype available. Appendix S1. Supporting Information Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. 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