Table 1.

RS frequency in patients treated with therapeutic regimens based on pathway inhibitors.

Number of CLL Patients	Study Population	Treatment	RS Prevalence (%)	Reference
391	Relapsed	Ibrutinib, ofatumumab	1	Byrd, 2014 [23]
29	Progressive untreated	Ibrutinib	3	O’Brien, 2014 [24]
194	R/R	Venetoclax-rituximab	3	Seymour, 2018 [19]
127	R/R	Ibrutinib	5	Jain, 2015 [25]
84	17p deleted or ≥65 years	Ibrutinib	6	Ahn, 2017 [21]
358	Treatment-naïve	Acalabrutinib, Obinutuzumab	2	Sharman, 2020 [18]
51	17p deleted	Ibrutinib	6	Farooqui, 2015 [26]
178	BCRi treated	Ibrutinib, idelalisib	7	Mato, 2016 [27]
113	Treatment-naïve	Ibrutinib-obinutuzumab	0	Moreno, 2019 [17]
85	R/R	Ibrutinib	8	Byrd, 2013 [28]
116	R/R	Venetoclax	16	Roberts, 2016 [29]
67	R/R, 17p deleted	Venetoclax	25	Anderson, 2017 [30]
2975	R/R	B, F, C, Clb, rituximab, obinutuzumab, ibrutinib, venetoclax	3	Al-Sawaf, 2021 [15]
195	R/R	Ibrutinib	10	Munir, 2019 [20]

Abbreviations: RS, Richter Syndrome; R/R, relapsed/refractory; BCRi, B-cell receptor pathway inhibitors; B, bendamustine; F, fludarabine; C, cyclophosphamide; Clb, chlorambucil.