Efficacy of Idelalisib and Rituximab in Relapsed/Refractory Chronic Lymphocytic Leukemia Treated Outside of Clinical Trial. a Report of the Gimema Group
Authors: Rigolin Gian Matteo , Frustaci Annamaria , Piciocchi Alfonso , Visentin Andrea , Vitagliano Orsola , Coscia Marta , Farina Lucia , Gaidano Gianluca , Murru Roberta , Varettoni Marzia , Arcaini Luca , Cibien Francesca , Paolini Rossella , Sportoletti Paolo , Pietrasanta Daniela , Molinari Anna Lia , Quaglia Francesca M. , Laurenti Luca , Marasca Roberto , Marchetti Monia , Chiarenza Annalisa , Mauro Francesca Romana , Perbellini Omar , Mannina Donato , Sancetta Rosaria , Olivieri Attilio , Molica Stefano , Pane Fabrizio , Patti Caterina , Iliariucci Fiorella , Gozzetti Alessandro , Califano Catello , Galieni Piero , Augello Accursio Fabio , Vallisa Daniele , Cura Francesca , Crea Enrico , Fazi Paola , Zamprogna Giulia , Krampera Mauro , Trentin Livio , Ferrara Felicetto , Gentile Massimo , Montillo Marco , Foà Robin , Cuneo Antonio 
Published: November 2020

Background. The PI3Kδ inhibitor idelalisib given in combination with rituximab in relapsed/refractory chronic lymphocytic leukemia (R/R CLL) has been associated with an objective response in 81% of cases with a median PFS of 20.3 months in a phase-3 clinical trial (Sharman et al, JCO 2019). Because the efficacy of new drugs reported in clinical trials may not translate into similar results in the day-to-day practice, we performed an observational retrospective-prospective study on the efficacy and safety of idelalisib and rituximab (IR) in R/R CLL patients treated outside of clinical trials in Italian centers belonging to the GIMEMA group.
Methods. R/R CLL patients treated with IR outside of clinical trials between July 2014 and May 2017 were enrolled. Treatment was initiated at symptomatic progression; treatment response and disease progression were assessed according to the NCI criteria. The data were extracted from the medical files and entered into case record forms (CRF) by each treating physician. Computerized and manual consistency checks were performed by the GIMEMA data center on newly entered forms and queries were issued in case of inconsistencies. The primary endpoint was progression-free survival (PFS), secondary endpoints were overall response rate (ORR), the percentage of patients on treatment at 12, 24 and 36 months, overall survival (OS) and response to the subsequent anti-leukemic treatment.
Results. 149 R/R CLL patients from 35 Italian centers were included in the study. The baseline characteristics are shown in Table 1.
At a median follow-up of 39.4 months, the median PFS was 22.9 months (95% CI 20.5-28.8). In univariate analysis, a shorter PFS was associated with ≥3 lines of therapy (p=0.0175) (Fig. 1a). The ORR (CR + PR) was 72.5%. Age ≤70 yrs (p=0.037) and a PS &lt;1 (p=0.014) were associated with a higher ORR. The median OS was 44.5 months (95% CI 32.5-NR). In univariate analysis, a shorter OS was associated with advanced stage (p=0.016) and ≥3 lines of therapy (p=0.0009) (Fig. 1b). Forty-eight%, 24.3% and 11.8% of patients were still receiving the study drug at 12, 24 and 36 months, respectively. Discontinuation at 12 months was due to toxicity in 60.8% of cases. Variables associated with a treatment duration &lt;12 months were advanced clinical stage (p=0.029) and a poor ECOG performance status (p&lt;0.001). Overall, 59 patients received a subsequent treatment, with an ORR of 64.4%. Median follow-up for these patients was 11 months (range 0.1-45.6). The 12-month OS were 85.5% (95% CI 74.6-98.1) for patients who discontinued RI for toxicity and 61.5% (95% CI 43.8-86.5) for those who discontinued for progression (p=0.0031) (Fig. 2). The only predictor for response to the new treatment was having received &lt;2 lines of therapy before RI (p=0.0153). Adverse events &gt;grade 3 during RI treatment were neutropenia (35% of cases), gastrointestinal disorders (17%), infections (17%) and transaminitis (6%).
Conclusions. The results hereby observed show that the efficacy of IR in a cohort in a real-life RR/CLL with a long follow-up is superimposable to those reported in the pivotal clinical trial, suggesting that the patient population who received IR in the day-to-day clinical practice mirrored that enrolled in the trial. Advanced clinical stage and 3 or more previous lines of therapy were associated with shorter PFS and OS. Interestingly, PFS and objective measures of efficacy such as the proportion of patients still on treatment at 12, 24 and 36 months, as well as OS, were not influenced by the TP53 status. Furthermore, the majority of patents responded to the subsequent anti-leukemic treatment and relatively durable responses were observed in patients who discontinued IR due to toxicity.

Disclosures
Rigolin: Abbvie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Gilead: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau. Visentin:Janssen: Honoraria; Gilead: Honoraria; Abbvie: Honoraria. Coscia:Shire: Honoraria, Membership on an entity's Board of Directors or advisory committees; Karyopharm Therapeutics: Research Funding; Gilead: 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, Speakers Bureau; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau. Farina:Abbvie: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees. Gaidano:Abbvie: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Astrazeneca: Membership on an entity's Board of Directors or advisory committees; Sunesys: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Murru:Janssen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Gilead: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Abbvie: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Varettoni:Roche: Consultancy, Membership on an entity's Board of Directors or advisory committees; AbbVie: Other: Travel/accommodations/expenses; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Travel/accommodations/expenses. Sportoletti:Janssen: Honoraria; AbbVie: Honoraria. Laurenti:Janssen: Honoraria; Gilead: Honoraria; AbbVie: Honoraria; Roche: Honoraria. Marasca:Janssen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Abbvie: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Roche: Membership on an entity's Board of Directors or advisory committees; Shire: Honoraria. Marchetti:Takeda: Other: Sponsored meetings; Gilead: Consultancy; Novartis: Speakers Bureau; Amgen: Speakers Bureau; AbbVie: Other: Sponsored meetings; Pfeizer: Other: Sponsored meetings. Mauro:Jannsen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Abbvie: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Takeda: Membership on an entity's Board of Directors or advisory committees; Octopharma: Consultancy; Astrazeneca: Membership on an entity's Board of Directors or advisory committees. Molica:Roche: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees; Abbvie: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Pane:Amgen: Consultancy, Other: Travel Expenses, Speakers Bureau; AbbVie: Consultancy, Other: Travel Expenses, Speakers Bureau; Daiichi Sankyo: Consultancy, Other: Travel Expenses; Jazz Pharmaceuticals: Consultancy, Other: travel expenses, Speakers Bureau; Novartis pharma SAS: Consultancy, Other: Travel Expenses, Research Funding, Speakers Bureau; Janssen: Other: Travel Expenses; Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celgene: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Gozzetti:Janssen: Honoraria, Research Funding; Amgen: Honoraria; Takeda: Honoraria. Galieni:Celgene: Honoraria; Takeda: Honoraria; AbbVie: Honoraria; Janssen: Honoraria. Krampera:Janssen: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees. Trentin:Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Abbvie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Octapharma: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees; Shire: Honoraria. Montillo:AbbVie: Honoraria, Speakers Bureau; F. Hoffmann-La Roche: Honoraria, Research Funding; Janssen: Honoraria, Speakers Bureau; Verastem: Honoraria; Gilead: Honoraria, Speakers Bureau; Astra Zeneca: Honoraria. Foà:Incyte: Speakers Bureau; Abbvie: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Roche: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Speakers Bureau; Roche: Membership on an entity's Board of Directors or advisory committees. Cuneo:Abbvie: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Astra Zeneca: Honoraria; Gilead: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Roche: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau.