INTRODUCTION

Richter transformation (RT) is the histologic transformation of CLL/SLL into an aggressive lymphoma, most commonly diffuse large B-cell lymphoma (DLBCL). We previously reported an incidence of 0.5% per year of RT in patients with newly diagnosed CLL and an incidence of 1% per year following initiation of therapy (Parikh, BJH, 2013). It is unknown whether these incidences have changed in the novel agent era.

METHODS

We identified patients with previously untreated CLL/SLL in the Mayo Clinic CLL Database who were seen within 12 months of diagnosis. Only patients with biopsy-proven DLBCL with histopathology confirmation at Mayo Clinic were included. Cumulative incidence methodology was used to display the time to development of RT with death as a competing risk (both from time of initial CLL/SLL diagnosis, and from start of CLL directed therapy). We defined the time period prior to February 2014 (FDA approval of ibrutinib for CLL) as the pre-novel agent era and the time period starting February 2014 as the novel agent era. Using Cox regression analysis, we compared the incidence of RT, both after initial CLL diagnosis and after initiation of CLL therapy, between patients diagnosed with CLL in the pre-novel agent era versus the novel agent era.

RESULTS

Between 1/2000 and 4/2023, 3347 patients were seen at Mayo Clinic. The median age at diagnosis was 65 years (range 21-97 years), and 66% patients were male. Baseline characteristics of patients at the time of CLL and RT diagnoses between the two treatment eras were similar, including distance in miles of primary residence from Mayo Clinic ( Table 1). The median follow-up for the entire cohort was 5.6 years (9.5 years for the pre-novel agent era cohort and 3.2 years for the novel agent era cohort). A total of 82 patients were diagnosed with RT (69 in the pre-novel agent era and 13 in the novel agent era).

Overall, the 1-, 5- and 10-year cumulative incidence rates for RT from the time of CLL/SLL diagnosis were 0.6% (95% CI: 0.4-0.9%), 1.8% (95% CI: 1.3-2.3%), and 3.0% (95% CI: 2.4-3.8%), respectively. Among the patients who received CLL/SLL therapy (n=1382), the 1-, 5-, and 10-year incidence rates for RT from the time of treatment start were 0.3% (95% CI: 0.1-0.8%), 3.3% (95% CI: 2.4-4.5%), and 4.9% (95% CI: 3.7-6.5%), respectively.

Among 1981 patients diagnosed with CLL/SLL in the pre-novel agent era, the 1- and 5-year incidence rates for RT from the time of diagnosis were 0.6% (95% CI: 0.4-1.1%) and 2.1% (95% CI: 1.5-2.8%), respectively. Among 1366 patients diagnosed with CLL/SLL in the novel agent era, the 1- and 5-year incidence rates following CLL/SLL diagnosis were 0.5% (95% CI: 0.2-1.1%) and 1.1% (95% CI: 0.6-2.2%), respectively. The RT incidence from time of CLL/SLL diagnosis was not significantly different between the pre-novel agent and novel agent era patients (hazard ratio [HR] 1.6, 95%CI 0.9-3.0, p=0.13).

Patients who received CLL/SLL treatment in the pre-novel agent era (n=926) and novel agent era (n=456) had subsequent 1-year incidence rates of RT of 0.3% (95% CI: 0.1-1.0%) and 0.2% (95% CI: 0.0-1.8%), respectively. The 5-year incidence rates for these groups were 3.7% (95% CI: 2.6-5.2%) and 1.9% (95% CI: 0.7-5.0%), respectively. Although an increased risk of RT after CLL/SLL directed therapy was observed in the pre-novel agent era compared to the novel agent era (HR 2.4, 95%CI: 0.9-6.1, p=0.07; Figure 1), this did not cross the threshold of statistial significance.

Among patients diagnosed in the pre-novel agent era who developed RT (n=69), CLL treatment prior to RT included: none, n=19 (28%); chemoimmunotherapy only, n=36 (52%); and novel agent, n=14 (20%; includes 11 treated with prior chemoimmunotherapy also). In contrast, among patients diagnosed in the novel agent era who developed RT (n=13), CLL treatment prior to RT included: none, n=8 (62%); and novel agent, n=5 (38%).

CONCLUSIONS

Patients who received CLL/SLL directed treatment appear to have a lower risk of RT in the novel agent era. This may be driven by the fact that none of the patients who developed RT in the novel agent era received chemoimmunotherapy. Whether novel agent use for CLL/SLL suppresses the development of RT or avoids the risk associated with cytotoxic chemotherapy-induced clonal evolution requires further study. Although limited by length of follow-up, our findings challenge the notion that RT incidence will increase in parallel with CLL patients living longer with novel agent treatments.

Wang:LOXO Oncology: Membership on an entity's Board of Directors or advisory committees, Research Funding; Genmab: Research Funding; Innocare: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Incyte: Membership on an entity's Board of Directors or advisory committees, Research Funding; Eli Lilly: Membership on an entity's Board of Directors or advisory committees, Research Funding; TG Therapeutics: Membership on an entity's Board of Directors or advisory committees; Genentech: Research Funding; Astra Zeneca: Membership on an entity's Board of Directors or advisory committees; BeiGene: Membership on an entity's Board of Directors or advisory committees; Novartis: Research Funding; Morphosys: Research Funding; Kite: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; AbbVie: Consultancy. Kenderian:Kite/Gilead: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Consultancy, Honoraria, Patents & Royalties, Research Funding, Speakers Bureau; Luminary therapeutics: Other: scientific advisory board ; Torque: Consultancy; CapstanBio: Consultancy, Other: Scientific advisory board; Humanigen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties, Research Funding, Speakers Bureau; Juno/BMS: Other: Membership on an entity's board of directors or advisory committees, Research Funding; MustangBio: Patents & Royalties; Sendero: Patents & Royalties; Mettaforge: Patents & Royalties; Lentigen: Research Funding; Tolero/Sumtomo: Research Funding; Morphosys: Research Funding; LEAHLabs: Consultancy, Current equity holder in private company, Research Funding. Muchtar:Protego: Consultancy. Koehler:AbbVie: Consultancy, Other: Advisory Board; Jannsen: Other: Advisory Board; Astra Zeneca: Other: Advisory Board. Tsang:Poseida Therapeutics: Current holder of stock options in a privately-held company. Kay:Dava Oncology: Membership on an entity's Board of Directors or advisory committees; boehringer ingelheim: Membership on an entity's Board of Directors or advisory committees; Beigene: Membership on an entity's Board of Directors or advisory committees; Behring: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; Dren Bio: Membership on an entity's Board of Directors or advisory committees; Astra Zeneca: Membership on an entity's Board of Directors or advisory committees; Agios Pharm: Membership on an entity's Board of Directors or advisory committees; Vincerx: Research Funding; Sunesis: Research Funding; Pharmcyclics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Genentech: Research Funding; Bristol Meyer Squib / Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Acerta Pharma: Research Funding; Abbvie: Membership on an entity's Board of Directors or advisory committees, Research Funding; Juno Therapeutics: Membership on an entity's Board of Directors or advisory committees. Ding:Merck: Consultancy, Honoraria, Research Funding; BeiGene: Consultancy, Honoraria, Research Funding; MEI pharama: Consultancy, Honoraria; Alexion: Consultancy, Honoraria; Octapharma: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; AstraZeneca: Research Funding; AbbVie: Research Funding; DTRM: Research Funding. Parikh:Boehringer Ingelheim Pharmaceuticals Incc: Membership on an entity's Board of Directors or advisory committees; Beigene: Membership on an entity's Board of Directors or advisory committees; Bristol Myers Squibb-Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Agios Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; AstraZeneca: Membership on an entity's Board of Directors or advisory committees; AbbVie Inc: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees; Pharmacyclics: Membership on an entity's Board of Directors or advisory committees, Research Funding; CSL Behring: Membership on an entity's Board of Directors or advisory committees; Juno Therapeutics: Membership on an entity's Board of Directors or advisory committees; Dava Oncology: Membership on an entity's Board of Directors or advisory committees; Accerta Pharmaceuticals: Research Funding; Dren Bio: Membership on an entity's Board of Directors or advisory committees; Genentech: Research Funding; Sunesis: Research Funding; Vincerx: Research Funding.

Figure 1
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2023
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