Thompson, Philip A

Abstract Richter transformation (RT) is defined as an aggressive lymphoma emerging in patients with chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL). Despite novel therapeutics developed in CLL, RT is associated with poor outcomes. In light of recent progress regarding the diagnostic procedures and therapeutic concepts of RT, an international group of experts, under the coordination of the European Research Initiative on CLL, has developed consensus recommendations for clinical procedures and future research on this disease. Patients with RT typically present with a rapid clinical decline, worsening B-symptoms, elevated lactate dehydrogenase, and/or rapidly enlarging lymphadenopathy. Workup should include a positron emission tomography–computed tomography scan for patients with suspected RT. An excisional biopsy should be taken from an accessible lesion, preferably with the highest fluorodeoxyglucose avidity, and analyzed for the presence of aggressive lymphoma. The molecular relationship to the original CLL clone(s) should be defined. Because no effective standard treatment for RT exists, patients should be treated in a clinical trial. Response of both RT and CLL should be assessed at an early time point, and survival end points should be prioritized in trial design. We hope that these recommendations can help to harmonize clinical and translational research and improve outcomes for patients with RT.

Introduction: Complex karyotype (CK, ≥3 chromosome (chr) abnormalities (abn)) is an important adverse prognostic indicator in chronic lymphocytic leukemia (CLL). CK at diagnosis (dx) of CLL, particularly with major structural chr abn (i.e. unbalanced translocation, add, marker, ring chr), called type-2 CK (CK2), has been associated with an increased risk of Richter transformation (RT) (Visentin Haematologica 2022). RT is defined as development of aggressive lymphoma, most often large B-cell lymphoma, in the setting of CLL. In patients (pts) with relapsed/refractory CLL treated with ibrutinib, CK as a continuous variable and the presence of polyploidy were independent predictors for RT. CK is a common finding at the time of RT, and high-CK (≥5) has been associated with short survival in RT, although previous studies predominantly included pts with prior chemoimmunotherapy (CIT) administration for their CLL. The prognostic significance of CK in pts with RT whose prior CLL-directed therapies include only non-CIT, as is the current standard of care for CLL, has not been evaluated. Methods: We conducted a multicenter, retrospective analysis of pts from 14 academic centers. Pts with RT diagnosed between 6/2011 to 6/2023, who had CLL-directed treatment that did not include prior CIT, with stimulated karyotype data available, were included. Pts who did not receive treatment for their CLL prior to developing RT were not included. Baseline pt, disease, and cytogenetics data were collected via chart review at time of CLL diagnosis and at the development of RT. Karyotype abn up to 20 were counted on both CLL tissue (peripheral blood or bone marrow) and RT tissue using IWGMC guidelines (Chun Leuk Res 2010). CK was categorized as CK1 (balanced abn, deletion, aneusomies) or CK2. Polyploidy was defined as ≥58 chrs. Karyotype was considered evolved if one or more chr abn were seen in a follow-up sample of CLL tissue that were not seen at CLL dx.TP53 disruption was defined as presence of del(17p) or TP53 mutation. Overall survival (OS) was measured from RT dx and estimated using the Kaplan-Meier method. Cox regression model was used to identify prognostic factors associated with OS. Results: A total of 64 eligible pts were identified. Median age at RT dx was 65 years (range 40-89) and 71.9% of pts were male. Of those evaluated (n=49), 79.6% had unmutated IGVH. Median number of therapies for CLL prior to RT was 1 (range 1-5) and included BTK inhibitor (n=37), BCL2 inhibitor (n=3), both (n=18), or other non-CIT treatment (n=6). At CLL diagnosis, 54.7% of pts had a CK, and the median number of chr abn was 3 (range 0-20). Of those with CK, 96.9% had a CK2, and 6.3% had a polyploid subclone. TP53 disruption was found in 46% of pts. At time of RT, chr analysis of CLL tissue was available for 38 pts and showed 78.9% had a CK, and the median number of chr abn was 8 (range 0-20). Polyploidy was found in 29.6%. TP53 disruption (46 pts evaluated) was found in 52.2%. Karyotype evolution from dx (35 pts evaluated) occurred in 74.3% of pts. In RT tissue, of those evaluated (n=29), 96.6% were clonally related to the preceding CLL. MYC translocation (45 pts evaluated) occurred in 17.8%. CK (20 pts evaluated) was found in 70%, with a median number of chr abn of 8 (range 0-20). Of those with CK, 33.3% had a polyploid subclone. With a median follow-up of 17.8 months (range 2.1-83.0) there were 42 deaths, with a median OS of 14.3 months (range 6.9-29.1). For this subset of patients with karyotype data available who would go on to develop RT, an exploratory univariable analysis for OS from RT found that increasing number of chr abn as a continuous variable at CLL dx was associated with worse OS (HR 1.10, 95% CI 1.02-1.19, p=0.01). Similarly, at RT, increasing number of chr abn in CLL tissue (HR 1.09, 95% CI 1.02-1.16, p=0.01) and in RT tissue (HR 1.09, 95% CI 1.01-1.18, p=0.03) was also prognostic of survival. Karyotype evolution in CLL tissue at RT (HR 3.02, 95% CI 1.02-8.94, p=0.05) was borderline significant for worse OS. Conclusions: Our multi-center study identified increasing number of chr abn at CLL diagnosis and at time of RT, and clonal evolution in the CLL tissue, are associated with worse OS in pts with RT whose CLL was treated without CIT. Limitations include incomplete cytogenetics data across the cohort and potential variability across institutions in cytogenetics laboratory practices. This provides further evidence for the clinical utility of chr analysis in the modern era of CLL therapy.

Abstract Patients with chronic lymphocytic leukemia (CLL) who develop Richter transformation (RT) have a poor prognosis when treated with chemoimmunotherapy regimens used for de novo diffuse large B-cell lymphoma. Venetoclax, a BCL2 inhibitor, has single-agent efficacy in patients with RT and is potentially synergistic with chemoimmunotherapy. In this multicenter, retrospective study, we evaluated 62 patients with RT who received venetoclax-based treatment outside of a clinical trial, in combination with a Bruton tyrosine kinase inhibitor (BTKi; n=28), rituximab, cyclophosphamide, doxorubicin, vincristine, prednisone (R-CHOP) (n=13), or intensive chemoimmunotherapy other than R-CHOP (n=21). The best overall and complete response rates were 36%/25%, 54%/46%, and 52%/38%, respectively. The median progression-free and overall survival estimates for the same treatment groups were 4.9/14.3 months, 14.9 months/not reached, and 3.3/9 months, respectively. CLL with del(17p) was associated with a lower complete response rate in the total cohort (odds ratio [OR] 0.15; 95% confidence interval [CI] 0.04-0.6; p=0.01) and venetoclax-naïve subgroup (OR 0.13; 95%CI 0.02-0.66; p=0.01). TP53 mutated CLL was associated with a lower complete response rate (OR 0.15; 95%CI 0.03-0.74; p=0.02) and shorter progression-free survival (hazard ratio 3.1; 95%CI 1.21-7.95; p=0.02) only in venetoclax-naïve subgroup. No other clinical or baseline characteristics, including prior venetoclax treatment for CLL, showed statistically significant association with outcomes. Grade 3-4 neutropenia and thrombocytopenia events were most frequent with intensive chemoimmunotherapy + venetoclax; grade 3-4 infection rates were similar across treatment groups. In this difficult-to-treat RT patient population, venetoclax-based combination regimens achieved high response rates, with durable remission and survival observed in a subset of patients.

Background:Richter transformation (RT) occurs in up to 10% of patients with chronic lymphocytic leukemia (CLL), typically presents as an aggressive diffuse large B-cell lymphoma (DLBCL) and is associated with poor survival. RT has no approved standard therapy; and clinical trial enrollment is the preferred first line of therapy. Pirtobrutinib, a highly selective, non-covalent (reversible) BTKi, that inhibits both wildtype and C481-mutant BTK with equal low nM potency, has favorable oral pharmacology that enables continuous BTK inhibition throughout the dosing interval. Pirtobrutinib demonstrated durable overall response rates (ORR) and was well tolerated in patients (pts) with poor-prognosis B-cell malignancies regardless of prior therapy. Here we provide updated safety and efficacy of pirtobrutinib in RT pts from the phase 1/2 BRUIN trial (NCT03740529). Methods: Pts with previously treated, histologically confirmed RT were eligible in the global, multicenter, phase 1/2 BRUIN study. Pts with untreated RT became eligible after Amendment 10. All but one patient received the recommended phase 2 dose of 200 mg daily. Key endpoints included investigator-assessed ORR, DoR per Lugano 2014 criteria, OS, and safety. A data cut of 05 May 2023 was utilized. To assess clonal relationship, IGH rearrangement studies were done on tissue biopsies with RT involvement, and baseline blood or bone marrow (BM) samples with CLL involvement. Results: Among all pts with RT (N=82) the median age was 67 (range, 26-95) and the median total number of lines of prior systemic therapy was 4 (range, 0-13). Pts with prior treatment had a median of 2 CLL-directed therapies and 2 RT-directed therapies. Eight pts did not have a previous line of RT-directed therapy, and 1 patient received neither RT- nor CLL-directed therapy. Common prior RT- and CLL-directed therapies (RT, CLL) included: chemotherapy (76%, 52%), cBTKi (34%, 62%), anti-CD20 antibody (78%, 66%), BCL2i (38%, 49%), stem cell transplant (SCT; 6%, 7%), and CAR-T (11%, 4%). Of 29 pts with bone marrow screening, 41.4% had CLL alone present in BM, 13.8% had DLBCL present and 24.1% had both CLL and DLBCL present. For 39 pts with available PET data, the median SUVmax was 19.1 (range, 2.6-41.2). For all 82 pts, the ORR was 50.0% (95% CI, 38.7-61.3) including complete (13.4%, n=11) and partial (36.6%, n=30) responses. For 61 pts who received prior cBTKi therapy, the ORR was 45.9% (95% CI 33.1-59.2). Among 28 pts with an RT-directed cBTKi and 51 pts with prior CLL-directed cBTKi, the ORR was 42.9% (95% CI, 24.5-62.8) and 43.1% (95% CI, 29.3-57.8), respectively. In 50 pts who discontinued prior cBTKi due to disease progression, the ORR was 42.0% (95% CI, 28.2-56.8). At median follow-up time of 9.7 months, the median DoR for all 82 RT pts was 7.4 months (95% CI, 3.1-19.1) and the estimated rate at 12 months was 45.9% (95% CI, 28.3-61.8). The median time on treatment for the 41pts who responded to treatment was 8.3 months. Eight pts stopped pirtobrutinib to pursue curative-intent allogeneic SCT and DoR was censored at the last preceding disease assessment. At a median survival follow-up of 18.3 months, the median OS for the entire RT cohort was 12.5 months (95% CI, 6.9-20.5). At 18 months, the OS rate was 44.3% (95% CI, 32.5-55.4). Frequent treatment-emergent adverse events (TEAE) in the RT cohort (n=82) were neutropenia/decreased neutrophil count (29.3%, n=24), fatigue (24.4%, n=20) and diarrhea, dyspnea, thrombocytopenia, and pyrexia (18.3% each, n=15). Common grade ≥3 TEAEs were neutropenia/decreased neutrophil count (23.2%, n=19), thrombocytopenia (11.0%, n=9), plus anemia and sepsis (9.8% each, n=8). Any grade hypertension (3.7%, n=3) or atrial fibrillation (1.2%, n=1) were infrequent. Three pts (3.7%) had treatment-related AEs leading to dose reductions, but no pt had a treatment-related AE leading to pirtobrutinib discontinuation. Analyses of clonality will be presented. Conclusions: Continued follow-up from BRUIN demonstrates encouraging response and OS in pts with RT. Pirtobrutinib remains well-tolerated with low rates of discontinuation and manageable safety profile. While RT remains a challenging diagnosis, pirtobrutinib represents a potential treatment option that warrants further investigation.

Background: Richter Transformation (RT) refers to the development of an aggressive lymphoma in the setting of chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL). Small molecule inhibitors (SMI), such as the Bruton tyrosine kinase inhibitors (BTKi) and BCL2 inhibitors (BCL2i), have revolutionized the treatment of CLL/SLL. Prior studies evaluated outcomes of patients (pts) with RT in an era where chemoimmunotherapy (CIT) was typically used to treat CLL/SLL. Now that SMI are standard of care, fewer pts with CLL/SLL receive CIT, therefore we sought to determine which variables predict survival in pts who developed RT without prior CIT exposure for CLL/SLL. Methods: We conducted an international multicenter retrospective study of pts from 11 academic centers. Pts with RT occurring as large B-cell lymphoma who did not previously receive CIT (e.g., fludarabine, cyclophosphamide, bendamustine, chlorambucil) for their CLL/SLL were included. We collected pt, disease, and treatment (tx) characteristics. RT was categorized into 3 groups: “Concurrent RT,” defined as RT and CLL/SLL diagnosed simultaneously (within 3 months [mos]); “RT w/o prior CLL/SLL tx,” defined as RT and CLL/SLL diagnosed >3 mos apart with the CLL/SLL never treated; and “RT with prior non-CIT tx for CLL/SLL” defined as having received prior CLL/SLL tx. Overall survival (OS) was measured from RT diagnosis (Dx) and estimated using the Kaplan-Meier method. Cox regression model was used to identify prognostic factors associated with OS. Results: 242 pts were identified. At CLL/SLL Dx, 66% of pts had unmutated IGHV, 37% had del17p/ TP53 disruption, and 20% had trisomy 12. At RT Dx, 56% of the RT with prior non-CIT tx for CLL/SLL group had a del17p/ TP53 disruption versus 27% for the concurrent RT group and 18% for the RT w/o prior CLL/SLL tx groups. Median time from CLL/SLL Dx to RT Dx was 47 mos (range 3-394) for RT w/o prior CLL/SLL tx and 46 mos (range 4-218) for RT with prior non-CIT tx for CLL/SLL. Pts with prior non-CIT tx for CLL/SLL received a median of 1 (range 1-5) prior tx. 86% of pts previously received a BTKi or a BCL2i for tx of CLL/SLL (54% BTKi only, 5% BCL2i only, 27% both). The remaining 14% had been treated with an anti-CD20 monoclonal antibody (MoAb), steroids, lenalidomide, radiation, or alemtuzumab. 85% of pts developed RT while on active tx with SMI. Median age at RT Dx was 69 years (range 37-92). At RT Dx, 38% and 21% of pts had del17p/ TP53 disruption, and trisomy 12 in CLL/SLL tissue, respectively. At RT Dx, there was no difference in highest SUV on PET (median 16, range 2.9-65.6), LDH (median 325, range 103-8162, ULN range 180-271), largest lymph node in diameter (median 4.9 cm, range 0-17.1), Ki-67 (median 80%, range 5%-100%), rate of GCB subtype (27%), presence of MYC translocation (20%), or CLL/SLL and RT clonal relationship (81%) for those pts tested amongst the 3 groups ( Table). The most common 1 st line tx for RT was CIT with or w/o radiation and/or steroids (76%), followed by CIT plus SMI (13%), SMI single agent or combination (7%), and other (4%, which includes anti-CD20 MoAb). Median follow-up from RT Dx was 42.3 mos; the median OS for the entire cohort was 25.8 mos (95% CI: 16.8-49.1). Pts with RT after non-CIT tx for CLL/SLL had a significantly worse OS (median 8.2 mos [95% CI: 5.6-14.3]) than pts with concurrent RT (median 46.3 mos [95% CI: 23.8-96.9]) and RT w/o prior CLL/SLL tx (median 63.5 mos [95% CI: 28.3-70.3]) ( Figure). From an exploratory univariable analysis, we found RT after non-CIT tx for CLL/SLL compared to concurrent RT (HR 2.32 [95% CI: 1.55-3.46]), RT Dx age (HR for 5-year increase 1.14 [95% CI: 1.05-1.23]), del17p/ TP53 disruption (HR 2.27 [95% CI: 1.45-3.56]), and LDH (HR for 2-fold increase 1.37 [95% CI: 1.20-1.58]) were prognostic for worse OS. Conclusions: This is the largest cohort of pts who developed RT having received only SMI with no CIT for their CLL reported, thus reflecting the current treatment landscape. Despite being CIT-naïve, pts in our series who received tx for their CLL/SLL and then developed RT had a short OS, underscoring the need to develop better therapies for these pts. In contrast, as in other published analyses (Wang Haematologica 2020), pts w/o prior tx for CLL/SLL had more favorable outcomes, with a median OS of approximately 5 years. Further analysis to determine PFS and OS by tx for RT for pts who have been treated with SMI for their CLL/SLL is ongoing.

TPS7583 Background: Covalent (c) Bruton tyrosine kinase inhibitors (BTKi) have reshaped the treatment landscape for chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) and are now often used as initial therapy. The MURANO study established 2-year fixed duration venetoclax plus rituximab as a standard of care regimen for patients with relapsed or refractory CLL/SLL. However, its efficacy has not been formally assessed in CLL/SLL patients treated with a cBTKi, a common setting where this regimen is used in contemporary practice. Pirtobrutinib, a highly selective, non-covalent (reversible) BTKi, inhibits both wildtype and C481-mutant BTK with equal low nM potency, and has favorable oral pharmacology that enables continuous BTK inhibition throughout the dosing interval regardless of intrinsic rate of BTK turnover. In the phase 1/2 BRUIN study, pirtobrutinib demonstrated promising durable overall response rates (ORR) and was well tolerated in patients with pre-treated CLL/SLL regardless of prior therapy (including cBTKi), number of prior lines of therapy, BTK C481 mutation status, or reason for prior cBTKi discontinuation. The study's objective is to assess the superiority of adding time-limited pirtobrutinib to the MURANO regimen, hypothesized to prolong disease control in a largely BTKi-pretreated population. Methods: BRUIN CLL-322 (NCT04965493) is a randomized, open-label, global, phase 3 study comparing time-limited pirtobrutinib (200mg QD) plus venetoclax and rituximab versus venetoclax and rituximab in previously treated CLL/SLL patients. Approximately 600 patients, 80% who have been previously treated with cBTKi, will be randomized 1:1 and stratified by del(17p) status (yes/no) and prior BTKi experience (discontinuation due to progressive disease vs due to other reasons vs no prior BTKi exposure). Eligible patients are adults diagnosed with CLL/SLL and require therapy per iwCLL 2018 criteria who have received prior therapy that may or may not include a cBTKi. There are no restrictions on the number of lines of prior therapy. Key exclusion criteria include CNS involvement by CLL/SLL, Richter transformation at any time, prior BCL2 inhibitor or non-covalent BTK inhibitor, or a history of either allogeneic or autologous stem cell transplant, or chimeric antigen receptor T-cell therapy within 60 days prior to randomization. The primary endpoint is progression-free survival (PFS) per iwCLL criteria assessed by an independent review committee. Secondary endpoints include investigator assessed PFS, ORR, overall survival, time to next treatment, event-free survival, safety and tolerability, and patient-reported outcomes. Enrollment is ongoing for patients previously treated with BTKi and completed for BTKi naïve patients. Clinical trial information: NCT04965493 .

7505 Background: Novel agents (NA) targeting B cell receptor kinases and Bcl-2 have substantially improved outcomes in CLL; however, the development of RS in CLL patients (pts) on NAs has been observed, and has not been systematically evaluated. Methods: We retrospectively reviewed pts at 9 academic centers diagnosed with pathologically-confirmed RS from 2011-16. Informed consent was provided through IRB-approved protocols. Descriptive statistics were utilized and overall survival (OS) was calculated from RS diagnosis (dx) to death or last follow-up by Kaplan-Meier. Results: 71 pts who developed RS on NAs for CLL were identified. Median age at CLL dx was 55 yrs (range 21-82), median of 3 therapies (range 0-12) prior to the NA. 68% pts were fludarabine-refractory, and 5 pts (7%) had relapsed post alloHCT. Median time from CLL dx to initiation of NA was 68.5 mo. (range 1.1-246.2). FISH at NA initiation: del(17p) 30/61 (49%), del(11q) 15/61 (25%), trisomy 12 15/61 (25%). Complex karyotype was present in 40/53 (75%). 46/52 (88%) were IGHV unmutated, VH1-69 10/43 (23%), VH4-39 4/43 (9%). 59 (83%) pts were on a BTK inhibitor, 6 (8%) PI3K inhibitor, 6 (8%) venetoclax. RS histology: DLBCL (87%), plasmablastic (6%), Hodgkin (4%), 3% other. RS Ki-67%: >90 (23%), 75-90 (25%), 50-75% (25%), <50% (28%). Median time from start of NA to RS dx was 9.1 mo (range 0.9-48.2), with 65% developing RS within 12 mo. of starting NA. In 56 pts, 19 different regimens were used as initial RS therapy, including: R-EPOCH (36%), R-CHOP (20%), checkpoint blockade (9%), OFAR (7%), or a different NA (7%). Of the 48 pts evaluable for response, ORR was 42% (15% CR, 27% PR). In 29 evaluable pts receiving R-EPOCH/CHOP, ORR was 48% (21% CR). With a median follow-up of 10.6 mo., median OS was only 3.3 mo. (95%CI 2.2-6.0), though none of the 7 pts who achieved CR has died. Conclusions: We report to our knowledge the largest series of CLL pts developing RS on NAs. Pts often had high risk CLL, particularly complex cytogenetics, and RS frequently developed within the first year of NA therapy. Substantial variation exists in treatment, and outcomes are poor for those who do not achieve CR. Identification of molecular drivers of RS and development of novel treatment strategies are urgently needed.