Comparison of Tumor Lysis Syndrome (TLS) Risk Reduction and Incidence in Different Venetoclax-Based Combinations within the Randomized Phase 3 GAIA (CLL13) Trial
Authors: Fürstenau Moritz , Robrecht Sandra , Zhang Can , Von Tresckow Julia , Niemann Carsten Utoft , Kater Arnon P. , Gregor Michael , Thornton Patrick , Staber Philipp B. , Tadmor Tamar , Levin Mark-David , Da Cunha-Bang Caspar , Schneider Christof , Poulsen Christian Bjørn , Illmer Thomas , Schöttker Björn , Janssens Ann , Christiansen Ilse , Noesslinger Thomas , Baumann Michael , Simon Florian , De Silva Nisha , Fink Anna-Maria , Fischer Kirsten , Wendtner Clemens-Martin , Ritgen Matthias , Brüggemann Monika , Tausch Eugen , Van Oers Marinus H.J. , Geisler Christian H. , Stilgenbauer Stephan , Hallek Michael , Eichhorst Barbara 
Published: November 2021

Abstract
Background:
In early studies of venetoclax (ven) in CLL, severe tumor lysis syndromes (TLS) were observed leading to the implementation of multiple safety measures including a 5-week ramp up schedule. Since then, studies have consistently reported low rates of TLS in ven-treated patients (pts), most likely as a result of strict prophylactic and laboratory monitoring measures. Various lead-in regimens prior to the administration of ven were shown to be feasible and effective in reducing the risk of TLS in pts with CLL. However, no comparison of different pretreatment regimens has been performed so far in a prospective randomized trial. Using the set-up of the GAIA trial, we compared TLS incidence and formal TLS risk reduction between 3 different ven-based combinations.

Methods:
The phase 3 GAIA (CLL13) trial compared 3 different time-limited ven-based combinations against standard chemoimmunotherapy (CIT) in fit, treatment-naïve pts with CLL. Pts were randomized to receive CIT (FCR in pts ≤65 years; BR in pts &gt;65 years), ven and rituximab (RVe), ven and obinutuzumab (GVe), or ven, obinutuzumab and ibrutinib (GIVe). In RVe, GVe and GIVe, ven was added at cycle 1 day 22 (ramp up day 1) after a 21-day pretreatment with rituximab (1 dose), obinutuzumab (3 doses) or obinutuzumab (3 doses) plus ibrutinib (continuous) (Figure 1A).
The safety population (i.e. all pts who received study treatment) of the ven-containing arms was used for this analysis. TLS was reported according to Cairo-Bishop criteria (Cairo M, Bishop M. Br J Haematol. 2004). For TLS risk evaluation, the most recent available CT/MRI and absolute lymphocyte count (ALC) were used. TLS risk was evaluated at baseline and at ramp up day 1, before the first dose of ven. The patients were categorized retrospectively according to the following TLS risk categories: high (any lymph node [LN] with largest diameter ≥10 cm or any LN with largest diameter ≥5 cm and ALC ≥25 G/L), intermediate (any LN ≥5 cm to &lt;10 cm or ALC ≥25 G/L), low (all LN &lt;5 cm and ALC &lt;25 G/L).

Results:
The safety population of all ven-containing arms comprised of 696 pts (RVe: 237, GVe: 228, GIVe: 231). Baseline TLS risk was high in 22%, 23% and 19% of pts in the RVe, GVe and GIVe arm, intermediate in 62%, 65%, 67% and low in 10.5%, 14.7% and 12.4% of pts, respectively. After the first 21 days of treatment (i.e. at ramp up day 1), the fraction of pts with a reduction in TLS risk varied between the treatment arms with 31.7% (RVe), 71.4% (GVe) and 47.3% (GIVe) of pts decreasing by at least one TLS risk category (Figure 1B). With regard to TLS risk reduction, GVe was superior to RVe (p&lt;0.001) and GIVe (p&lt;0.001) while GIVe was superior to RVe (p=0.001)). At ramp up day 1, 2 patients (1.0%) in the GVe arm versus 60 patients (29.6%) in the GIVe arm had an ALC ≥25 G/L, likely as a correlate of ibrutinib-associated redistribution of lymphocytes to the peripheral blood, readily explaining part of the difference in TLS risk reduction between GVe and GIVe.
In total, 36, 30 and 19 cases of TLS occurred in 29 (12.2%), 26 (11.4%) and 19 (8.2%) pts in the RVe, GVe and GIVe arm. The majority of TLS cases were categorized as CTC grade 3 (28 [RVe], 19 [GVe], 12 [GIVe]), only few CTC grade 4 TLS were reported (1 [RVe], 2 [GVe], 3 [GIVe]). There were no cases of fatal TLS and no pts requiring dialysis due to TLS. In the obinutuzumab arms the majority of TLS cases occurred before ramp up day 1 (GVe: 76.7%, GIVe: 68.4%), i.e. before any venetoclax intake, in contrast 80.6% of TLS cases in the RVe arm were reported during ven ramp up (Figure 2). While there was no significant difference in the cumulative TLS incidence between the treatment arms (p=0.334), there was an increase in TLS occurring after ramp up day 1 in the RVe arm compared to GVe (p&lt;0.001) and GIVe (p=0.002).

Conclusions:
This analysis represents the first comparison of the formal TLS risk reduction and actual TLS incidence of different ven-based combinations in a randomized trial. GVe led to the highest TLS risk reduction, while the lowest number of TLS cases occurred in the GIVe arm. Most TLS cases in the GVe and GIVe arms occurred before the start of ven. RVe was least effective in reducing TLS risk and in contrast to the obinutuzumab-containing arms, the vast majority of TLS cases was reported during the ven ramp up. The relatively high incidence of TLS in comparison to other trials might partly be a consequence of using different reporting criteria (Cairo-Bishop vs Howard criteria). No fatal TLS occurred in any of the treatment arms.
Figure 1 Figure 1.

Disclosures
Von Tresckow: AbbVie: Honoraria, Other: advisory board, travel grant; Celgene: Other: travel grant; AstraZeneca: Honoraria, Other; Roche: Honoraria, Other: Reasearch support, travel grant; Janssen: Honoraria, Other: Reasearch support, travel grant. Niemann: Novo Nordisk Foundation: Research Funding; CSL Behring, Genmab, Takeda, Octapharma: Consultancy; Abbvie, AstraZeneca, Janssen: Consultancy, Research Funding. Kater: Abbvie: Honoraria, Other: Ad Board, Research Funding; Janssen, AstraZeneca: Other: Ad Board, steering committee, Research Funding; Genmab, LAVA: Other: Ad Board, Steering Committee; BMS, Roche/Genentech: Other: Ad Board, , Research Funding. Staber: Roche: Consultancy, Honoraria, Research Funding; AbbVie: Consultancy, Honoraria; Gilead: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; Astra Zeneca: Consultancy, Honoraria; Takeda: Consultancy, Research Funding; MSD: Consultancy, Honoraria; BMS: Consultancy, Honoraria; Incyte: Consultancy, Honoraria, Research Funding; Beigene: Consultancy, Honoraria. Tadmor: Janssen: Consultancy, Honoraria, Research Funding; AbbVie: Consultancy, Honoraria, Research Funding. Levin: Roche, Janssen, Abbvie: Other: Travel Expenses, Ad-Board. Poulsen: Janssen: Consultancy; Abbvie: Consultancy. Janssens: Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Trael Grant, Speakers Bureau; Novartis: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Sanofi: Consultancy; Beigene, AstraZeneca: Consultancy, Speakers Bureau; Abbvie, Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Noesslinger: AbbVie: Honoraria; Celgene: Honoraria; Roche: Honoraria; Jansen: Honoraria; AstraZeneca: Honoraria; Gilead: Honoraria. Simon: Gilead: Other: Travel support. Fink: AbbVie: Other: travel grant; Janssen: Membership on an entity's Board of Directors or advisory committees; AstraZeneca: Research Funding; Celgene: Research Funding. Fischer: Abbvie: Honoraria; Roche: Honoraria, Other: Travel Grants. Wendtner: Gilead: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel support, Research Funding; Genentech: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel support, Research Funding; AstraZeneca: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel support, Research Funding; F. Hoffmann-LaRoche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel support, Research Funding; Abbvie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel support, Research Funding; GlaxoSmithKline: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel support, Research Funding; Janssen Cilag: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel support, Research Funding; Mundipharma: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel support, Research Funding; Pharmacyclics: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel support, Research Funding. Ritgen: MSD: Consultancy, Other: Travel support; Chugai: Consultancy; Abbvie: Consultancy, Other: Travel support, Research Funding; Roche: Consultancy, Other: Travel support, Research Funding; Celgene: Other: Travel support. Brüggemann: Amgen: Other: Advisory Board, Travel support, Research Funding, Speakers Bureau; Incyte: Other: Advisory Board; Janssen: Speakers Bureau. Stilgenbauer: AbbVie, Amgen, AstraZeneca, Celgene, Gilead, GSK, Hoffmann-La Roche, Janssen, Novartis, Sunesis: Honoraria; AbbVie, Amgen, AstraZeneca, Celgene, Gilead, GSK, Hoffmann-La Roche, Janssen, Novartis, Sunesis: Other: Research Support; AbbVie, Amgen, AstraZeneca, Celgene, Gilead, GSK, Hoffmann-La Roche, Janssen, Novartis, Sunesis: Research Funding; AbbVie, Amgen, AstraZeneca, Celgene, Gilead, GSK, Hoffmann-La Roche, Janssen, Novartis, Sunesis: Consultancy. Hallek: Roche: Honoraria, Speakers Bureau; Gilead: Honoraria, Speakers Bureau; Mundipharma: Honoraria, Speakers Bureau; Janssen: Honoraria, Speakers Bureau; Celgene: Honoraria, Speakers Bureau; Pharmacyclics: Honoraria, Speakers Bureau. Eichhorst: Gilead: Membership on an entity's Board of Directors or advisory committees, Other: Travel, accomodation, expenses, Research Funding, Speakers Bureau; F. Hoffmann-La Roche Ltd: Membership on an entity's Board of Directors or advisory committees, Other: Travel, accomodation, expenses, Research Funding, Speakers Bureau; AbbVie: Membership on an entity's Board of Directors or advisory committees, Other: Travel, accomodation, expenses, Research Funding, Speakers Bureau; BeiGene: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; AstraZeneca: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Novartis: Membership on an entity's Board of Directors or advisory committees, Other: Travel, accomodation, expenses, Speakers Bureau; Celgene: Membership on an entity's Board of Directors or advisory committees, Other: Travel, accomodation, expenses, Speakers Bureau; Adaptive Biotechnologies: Speakers Bureau; Hexal: Speakers Bureau; ArQule: Membership on an entity's Board of Directors or advisory committees; Oxford Biomedica (UK): Membership on an entity's Board of Directors or advisory committees; MSD: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees, Other: Travel, accomodation, expenses, Research Funding, Speakers Bureau; Consultant Department I for Internal Medicine: Consultancy; University Hospital of Cologne: Current Employment.

OffLabel Disclosure:
The combination of obinutuzumab, venetoclax and ibrutinib is not approved for the treatment of CLL