Richter's Transformation Research Articles

Pregnancy in Patents with CLL Systematic Review

Introduction: Chronic Lymphocytic Leukemia (CLL) is a hematologic malignancy characterized by the clonal expansion of non-functional, mature-appearing lymphocytes in the bone marrow, peripheral blood, and lymphoid tissues. While cases of CLL during pregnancy are rare,it is associated with many complications. It was reported that women with CLL are more susceptible to infections due to a weakened immune system; possibly leading to more complications. There is also increased risk of thrombocytopenia, which can increase the risk of bleeding during pregnancy and childbirth. This review aimed at identifying literature available on the complications in CLL and pregnancy as well as the data available on the potential therapeutic strategies. Methods: A scoping review of case reports that discuss pregnant patients who were diagnosed with CLL were isolated. The effects of the disease on pregnancy outcomes regarding both mother and fetus were identified. Animal studies, reviews or non-original articles, and non-English articles were excluded from our study. FDA labels of medications in CLL were reviewed for data on pregnancy and animal outcomes. Information on those medications in pregnant patients were also identified where available. Results: The search strategy across four databases yielded 448 articles. After eligibility assessment, 14 articles were included in the review. Cases were subdivided according to timing of pregnancy relative to CLL diagnosis (diagnosed before pregnancy or during pregnancy at early or late gestational periods). The pre-pregnancy reports were further subclassified based on the presence or absence of infection during pregnancy. None of the cases reported required immediate initiation of CLL therapy and only one case reported mortality post-delivery. This occurred in a patient with Richter transformation and no prior CLL treatments. There were no reported fetal malformations or severe adverse outcomes related to the infants in any of the reported pregnancies ( Figure 2). The included studies provided insights into various aspects of CLL during pregnancy, including patient demographics, diagnosis timing and methods, acquired infections, changes in white blood cell count, treatment approaches, pregnancy outcomes, and complications for both mother and fetus. From the marketed pharmacological alternatives for CLL, most were not studied in pregnant humans with CLL ( Figure 1). However, venetoclax and rituximab have some data in pregnant patients with non-CLL indications. A case reported a pregnant refractory AML patient who received venetoclax with high dose cytarabine and mitoxantrone at 24 weeks of gestation. Bone marrow at 27 weeks showed complete remission and labor was induced at 28 weeks + 5 days after corticosteroid-induced lung maturation. The infant had hyperbilirubinemia, transient B-cell depletion and required ventilation. The baby recovered from all complications, although possible long-term effects are still unclear. The mother underwent allogeneic hematopoietic stem cell transplant. In a 30-year-old female (pregnant at 28 weeks) with primary CNS lymphoma, weekly rituximab was given for 4 weeks with dexamethasone. After delivery through C-section at 31 weeks, the patient started definitive treatment with chemotherapy and autologous transplant. The infant required brief mechanical ventilation and had transient B-cell depletion at delivery until 4 months post-delivery. The baby required a course of post-exposure acyclovir despite not developing an infection. Both mother and baby survived with good outcomes at last follow-up (4 years post-delivery) Conclusion: Despite the rarity of CLL occurrence during pregnancy, there is evident need of further studies and management guidelines in this population. This review provides insights into the possible pregnancy-related concerns in women with CLL at different disease stages. While watchful waiting is generally recommended due to CLL's slow progression, individual evaluation is crucial. If treatment is necessary, delaying therapy until the second or third trimesters may help mitigate the risk of fetal malformations. The increased susceptibility to infections resulting from the combined immunosuppressive effects of CLL and pregnancy should be carefully considered

Favezelimab (anti-LAG-3) Plus Pembrolizumab in Patients with Relapsed or Refractory Diffuse Large B-Cell Lymphoma (DLBCL): Cohort 3 of a Multicohort Open-Label Phase 1/2 Study

Background: Lymphocyte-activation gene 3 (LAG-3) is involved in the regulation of T-cell function and is commonly coexpressed with PD-1 on anergic T cells. Favezelimab (MK-4280), a humanized IgG4 anti-LAG-3 monoclonal antibody, plus pembrolizumab (anti-PD-1) is being investigated in the multicohort phase 1/2 MK-4280-003 efficacy and safety study (NCT03598608) in patients with relapsed or refractory (R/R) hematologic malignancies. Prior analyses of the combination demonstrated antitumor activity and manageable safety in patients with anti-PD-1-naive R/R classical Hodgkin lymphoma (cHL; cohort 1; ORR, 73%; CR, 30%) (Johnson NA et al. Blood. 2022;140(suppl 1):6540-2) and anti-PD-1-refractory cHL (cohort 2; ORR, 29%; CR, 9%) (Timmerman J et al. Blood. 2022;140(suppl 1):768-70). We present results from analysis of patients with R/R DLBCL enrolled in cohort 3. Methods: In this study, a safety lead-in phase (part 1) to determine the recommended phase 2 dose (RP2D) was followed by a dose-expansion phase (part 2). In cohort 3, eligible patients were ≥18 years old, had histologically confirmed R/R DLBCL that had progressed after ≥2 lines of previous therapy, including progression after autologous stem cell transplant (ASCT), had declined ASCT, or were ineligible for ASCT. Patients with Richter transformation were not permitted. In part 1, patients received favezelimab at a starting dose of 200 mg that was escalated to 800 mg plus pembrolizumab at 200 mg IV every 3 weeks (Q3W) per the modified toxicity probability interval method. In the dose-expansion phase, patients received favezelimab at the established RP2D of 800 mg plus pembrolizumab 200 mg Q3W for ≤35 cycles (~2 years). Response assessments were performed at weeks 12 and 24 (PET) and Q12W (CT). Adverse events (AEs) were graded per the NCI CTCAE v4.0. The primary end point was safety. ORR per IWG 2007 criteria by investigator review was a secondary end point. Exploratory end points included duration of response (DOR) and progression-free survival (PFS) per IWG 2007 criteria by investigator review and overall survival (OS). Results: A total of 25 patients with R/R DLBCL were enrolled. Patients had a median age of 73 years (range, 25-87), 10 (40%) had ECOG PS 0, and 15 (60%) had ≥3 prior lines of therapy. Most common subtypes of DLBCL were unspecified DLBCL (n = 12; 48%) and germinal center B-cell DLBCL (n = 6; 24%). At database cutoff (March 2, 2023), 1 patient (4%) was ongoing on treatment and 24 (96%) had discontinued because of progressive disease (n = 14), AEs (n = 2), clinical progression (n = 5), or patient noncompliance/nonstudy anticancer therapy (n = 3); 1 patient (4%) discontinued because of treatment-related AEs. No treatment-related deaths occurred. Sixteen patients (64%) had a treatment-related AE; the most common (≥5%) were cough (16%), increased blood alkaline phosphatase (12%), and hypothyroidism, constipation, infusion related reaction, increased AST, muscle spasms, headache and pruritis (8% each). Grade 3 or 4 treatment-related AEs occurred in 4 patients (16%; 1 grade 3 lymphocytic hypophysitis, 1 grade 3 infectious enterocolitis, 1 grade 3 increased AST, 1 grade 3 increased ALT, 1 grade 3 increased amylase, and 1 grade 4 decreased neutrophil count). AEs of clinical interest occurred in 5 patients (20%); only one grade ≥3 occurred (grade 3 hypophysitis). The median (range) time from first dose to data cutoff was 25.9 (19.7-52.1) months. The objective response rate was 12% (95% CI, 2.5-31.2; [2 CR, 1 PR]). Among 17 patients with a postdose scan, 7 (41%) had a reduction from baseline in target lesion size, and 6 (35%) had ≥50% reduction from baseline. Median DOR was not reached (range, 3.0+ to 16.9+ months); 1 responder had an observed response duration of ≥12 months. Median PFS was 2.1 months (95% CI, 1.1-2.7); 12-month PFS rate was 12%. As of the data cutoff, 20 patients (80%) had died. Median OS was 6.4 months (95% CI, 2.3-15.8); 12-month OS rate was 43%. Conclusion: Favezelimab 800 mg plus pembrolizumab 200 mg had limited antitumor activity in patients with DLBCL in cohort 3. Analyses are underway to identify biomarkers predictive of response to the combination of favezelimab and pembrolizumab. The safety profile was manageable and consistent with that observed in other cohorts in the study.

Initial Results of a Phase 2 Study of Venetoclax Added to Ibrutinib to Eliminate Ibrutinib Resistance Mutations in CLL

CONCLUSION BTK inhibitors (BTKi) are an important treatment for CLL. As BTKi are given until intolerance or disease progression, resistance is a major challenge. Progressive disease (PD) during BTKi treatment is associated with mutations BTK itself, or the immediate downstream protein, PLCG2. These can be detected 9-12 months prior to PD allowing for intervention. Venetoclax (VEN) is effective after IBR treatment, decreases BTK C481S mutation VAF, and can be combined with IBR. Based on these data, this phase 2 study adding VEN to IBR in patients (pts) with resistance mutations (RMUT) was conducted to test the hypothesis that adding VEN could eliminate molecular resistance. CLL pts taking IBR and with a detectable RMUT with or without PD were eligible. Included RMUT were in BTK at C481 and T474 or in PLCG2 at L845, D334, D1140, R665, and S707. Eligible pts continued IBR and added VEN. VEN was given in cycles (C) of 28 days with standard 5-week dose ramp-up to 400mg daily. Response was assessed after C12 and C24 by iwCLL 2008 criteria. Pts achieving a complete remission (CR) or CR with incomplete marrow recovery (CRi) and undetectable minimal residual disease (uMRD) to a level of 10-4 in both blood and marrow discontinued treatment. Those without a uMRD CR/CRi continued through C24 then discontinued if in uMRD CR/CRi. If this response was still not achieved after C24, they stopped IBR and continued VEN alone. Sequencing for RMUT was performed using an assay with a sensitivity of ≥0.5% VAF on sorted CD19+ B-cells. The primary endpoint is the rate of undetectable RMUT after C12 of IBR and VEN. Secondary endpoints are rate of uMRD CR/CRi after C12, progression-free (PFS), and overall survival (OS). C12 assessments missed due to the COVID-19 pandemic were considered non-assessable (NA). A second analysis included delayed C12 assessments. Adverse events (AEs) were graded according to the CTCAE v5 except hematologic AEs which used iwCLL criteria. Kaplan Meier methods were used to assess PFS and OS. All statistical analyses were performed using SAS version 9.4 (SAS Institute, Inc., Cary, NC). Data cut was 7/13/2023. A total of 28 pts were enrolled between 3/2019 and 2/2022 with baseline characteristics in the Table. The median follow up was 31.7 months (range 2.8-47.0) and 8 (29%) pts remain on treatment, 9 (32%) in follow up off treatment, 10 (40%) off study, and 1 (4%) died. BTK C481S testing was available after baseline at time of analysis. After C12, 13/27 (48%) pts who had a BTK C481S mutation at baseline had undetectable BTK C481S (uBTK C481S). This increased to 16/27 (59%) with C12 delayed assessments. 19/27 (70%) pts had uBTK C481S at anytime on study with a median time to uBTK C481S of 6 months (range 2.0-19.8). Of these 6/19 (32%) regained detectable BTK C481S with a median duration of uBTK C481S of 13.8 months (range 5.3-28.8) and 3/6 had PD. After C12 the overall response rate (ORR) was 71% (4 CR, 4 CRi, 12 partial remissions [PR], 4 stable disease [SD], 1 PD, 3 NA). Including delayed assessments (at C16, C19, and C19), the ORR was 79% (NA->PR n=2, PR->CR n=1). uMRD CR/CRi was attained in 5/28 (18%) and 6/28 (21%) pts after C12 and including delayed assessments, respectively. 12/28 (43%) pts discontinued treatment due to response: 9/28 (32%) in uMRD CR/CRi (C12 n=4, C19 n=1, C25 n=4), 3/28 (11%) electively in CR with detectable MRD (n=1, C12) or PR with uMRD (n=2, C25). Eight (36%) pts had PD with 1 Richter Transformation. The median PFS and OS were 40.7 months (95% CI: 35.9-not reached) and not reached, respectively (Figure). Hematologic AEs were frequent with lymphopenia (75%, 46% grade [gr] 3+), thrombocytopenia 68%, 7% gr 3+), neutropenia (61%, 14% gr 3+), and anemia (43%, 0% gr 3+). AEs experienced by >40% of pts were hypocalcemia (75%), diarrhea (75%), weight loss (57%), hypertension (57%), increased lactate dehydrogenase (54%), nausea (54%), dizziness (50%), vomiting (50%), flu like symptoms (43%), and neoplasms (43%). Gr 3 non-hematologic AEs occurring in >10% of pts were hypertension (21%) and diarrhea (14%). Seven (25%) patients had COVID-19 (all gr 2). There were no episodes of tumor lysis syndrome. In this phase 2 study, the addition of VEN to IBR decreased the BTK C481S mutation below the detection limit in 59% of pts after 12 cycles of treatment. This combination allowed 32% of pts to discontinue treatment in deep remission. The median PFS (40.7 months) supports further investigation of this approach.

Bellwave-010: Phase 3, Open-Label, Randomized Study of Nemtabrutinib Plus Venetoclax Versus Venetoclax Plus Rituximab in Patients with Relapsed/Refractory Chronic Lymphocytic Leukemia/Small Lymphocytic Lymphoma Following at Least One Prior Therapy

Background: Venetoclax + rituximab (VR) is a standard therapy among patients with chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) who have relapsed after at least 1 line of prior therapy. However, there is an unmet need for more effective treatments. Bruton's tyrosine kinase (BTK) is a critical signaling molecule in the pathogenesis of CLL, and inhibitors of BTK have resulted in significant improvements in survival for patients with CLL. Nemtabrutinib is a noncovalent, reversible, competitive inhibitor of BTK that does not require the C481 residue of BTK for binding and inhibition of kinase activity. As a result, nemtabrutinib can target both wild-type and C481-mutant forms of BTK. Results from the ongoing BELLWAVE-001 study have demonstrated manageable safety and durable antitumor activity of nemtabrutinib in patients with CLL/SLL with and without C481 mutations. The randomized, active-controlled, open-label, phase 3 BELLWAVE-010 study (NCT05947851) is designed to investigate the efficacy and safety of nemtabrutinib + venetoclax versus VR as second-line (2L) or later treatment for patients with relapsed/refractory (R/R) CLL/SLL. Study Design and Methods: Patients aged ≥18 years with active CLL/SLL that is relapsed/refractory to at least 1 prior therapy per the iwCLL 2018 criteria, an ECOG performance status of 0-2, and adequate organ function are eligible. Patients with Richter transformation, active central nervous system involvement, or severe bleeding disorder are excluded. Approximately 720 patients will be enrolled in 2 parts: an open-label, nonrandomized dose escalation and confirmation phase (part 1) to evaluate safety and determine the optimal dose of nemtabrutinib in combination with venetoclax and an open-label, parallel-group, randomized phase (part 2) comparing the efficacy and safety of nemtabrutinib + venetoclax with VR. In part 1, 30 patients will be enrolled to establish the dose of nemtabrutinib using a modified toxicity probability interval design. Patients will receive nemtabrutinib at 2 dose levels (45 mg PO QD starting dose, escalating to 65 mg PO QD) for 28 days followed by the combination of nemtabrutinib + venetoclax (20-400 mg PO QD ramp up over 4 weeks). In part 2, approximately 690 patients will be randomly assigned 1:1 to receive either nemtabrutinib at the recommended dose for 28 days followed by the combination of nemtabrutinib + venetoclax (20-400 mg PO QD ramp up over 4 weeks) or venetoclax (20-400 mg PO QD ramp up over 4 weeks) + rituximab (or rituximab biosimilar; 375 mg/m 2 at week 6 followed by 500 mg/m 2 Q4W starting at week 10 until week 26 [total 6 doses]). Patients will receive study treatment for ~2 years or until unacceptable toxicity, disease progression, or other discontinuation criteria are met. Randomization will be stratified by BTK-C481 mutation status (detected vs not detected; determined by droplet digital PCR with a limit of detection of approximately 0.01%-0.1%), geographic region (US/Canada vs Europe vs rest of world) and risk (high risk [del(17p) and/or TP53-mutated and/or IGHV-unmutated] vs low risk [absence of high-risk factors]). Response will be assessed (including imaging, physical examination, constitutional symptoms, hematological evaluations, and bone marrow biopsy as required) every 12 weeks up to week 97 and every 24 weeks thereafter or more frequently if clinically indicated. Adverse events will be monitored up to 30 days after treatment cessation (90 days for serious adverse events) and will be graded per NCI CTCAE, version 5.0. Hematologic toxicities will be evaluated according to iwCLL 2018 criteria. Patient-reported outcomes will be assessed using the EORTC QLQ-C30, EORTC QLQ-CLL17, and EQ-5D-5L questionnaires. The primary end points for part 1 are safety and tolerability, including dose-limiting toxicities, and to establish the recommended dose of nemtabrutinib in combination with venetoclax. The primary end point for part 2 is PFS as assessed per iwCLL 2018 criteria by blinded independent central review (BICR). Secondary end points for part 2 include undetectable minimal residual disease in bone marrow at month 14 as assessed by central laboratory, ORR, and DOR per iwCLL 2018 criteria by BICR, OS, and safety. Exploratory end points include ORR including partial response with lymphocytosis, pharmacokinetics, and health-related quality of life.

36-Month Follow-up Results of the Gimema ‘Veritas’ Trial of Front-Line Venetoclax and Rituximab (VenR) in Young and Fit Patients with Chronic Lymphocytic Leukemia and an Adverse Biologic Profile

Introduction: Based on the efficacy of the fixed-duration venetoclax and rituximab combination (VenR) in the setting of relapsed/refractory (R/R) patients with chronic lymphocytic leukemia (CLL), we investigated the efficacy and safety of the front-line VenR regimen in young (≤65 years) and fit patients with CLL and an unfavorable biologic profile in the GIMEMA LLC1518 VERITAS trial. Here, we report the 36-month updated results of this phase II, single-arm, multicenter, front-line study for young patients with CLL carrying an unmutated IGHV profile and/or a TP53 disruption. Methods: Seventy-five CLL patients requiring treatment, according to the International Workshop on CLL (iwCLL) criteria, were enrolled between October 2018 and May 2020. Treatment consisted of the five-week Ven ramp-up, six-monthly courses of the VenR combination, followed by six monthly courses of Ven single agent. Patients received tumor lysis syndrome (TLS) prophylaxis with urate-reducing agents and oral or iv hydration. The primary endpoint of this study was the complete remission (CR) rate assessed at the end of treatment (EOT, month 15) according to the iwCLL criteria. Measurable/minimal residual disease (MRD) was assessed on the peripheral blood (PB) and bone marrow (BM) by ASO-PCR at baseline, EOT and during the follow-up. MRD was categorized as undetectable (uMRD) with a cut-off of <1 cell in 10,000 leukocytes. Results: The median age of patients was 54 years (range 38-65); 96% had unmutated IGHV, 9 (12%) had TP53 disruption, and 4% showed mutated IGHV with TP53 disruption. At the EOT, the overall response rate (ORR) was 94.7%, with a CR rate of 76%. On an intention-to-treat basis, 52 (69.3%) patients showed a response with uMRD in the PB and 44 (58.7%) in the BM. At 33 months from the EOT, uMRD was maintained by 50% of patients who had achieved an uMRD in the PB and by 57% of those with a prior uMRD in the BM. The 33-month PB MRD-free survival was 50% (Figure 1). In multivariate analysis, factors associated with a significantly shorter MRD-free survival were the presence of an unmutated IGHV associated with a TP53 disruption (HR: 3.43 [95%CI: 1.13-10.4]; p=0.029), Binet B stage (HR: 0.16 [95%CI: 0.06-0.43]; <0.001) or, Binet C stage (HR: 0.19 [95%CI: 0.07-0.52]; p=0.001), while the clinical response, CR, or PR, did not show a significant impact. Three patients have died due to COVID-19. Despite iv hydratation, the administration of anti-uric acids, fatal TLS occurred in a patient who used self-administered fentanyl patches for analgesis purposes during the ramp-up phase. The 36-month OS was 96%. A further lymphoproliferative disorder was diagnosed in 2 patients (follicular lymphoma, 1; large granular cell leukemia, 1) and a second malignancy in 1 (prostate cancer), while no cases of Richter transformation were recorded. No unexpected adverse events were observed during the follow-up. Conclusions: The updated data from the VERITAS trial show that in young and fit patients with adverse genetic characteristics the front-line VenR combination was an effective regimen with high rates of deep responses with uMRD. Furthermore, at 33 months from the EOT, uMRD was maintained in the PB and BM in about half of the patients.

Chronic Lymphocytic Leukemia and Fatal Tissue Infiltration

Chronic lymphocytic leukemia (CLL) is typically characterized as an indolent process that is most often a comorbid condition rather than an immediate cause of death. While it is well-known that CLL can infiltrate tissues and manifest as small lymphocytic lymphoma, diffuse parenchymal infiltration with perforation and hemorrhage is most often associated with more aggressive lymphomas, such as diffuse large B-cell lymphoma. Here we present a series of three cases of CLL in which fatal hemorrhage (two spontaneous and one procedure-related) resulted from tissue compromise due to infiltration of organ parenchyma by the patient's known CLL. In the first case, the patient died of spontaneous duodenal perforation and hemorrhage associated with CLL. This patient also had heart failure related to myocardial infiltration and diffuse hepatic infiltration. A second patient died of spontaneous pulmonary hemorrhage associated with CLL. The final case involved fatal pulmonary hemorrhage during bronchoscopy in a patient with unsuspected bronchial involvement by CLL. At autopsy, all three cases showed histologic and immunohistochemical features of typical CLL. None of the cases showed evidence of Richter transformation, and none of the patients had clinically evident coagulopathy. The literature contains few reports of parenchymal infiltration by CLL with fatal perforation or hemorrhage. This pattern may represent an under-appreciated mechanism of CLL contribution to morbidity and mortality. Further characterization of how CLL invades tissue and ultimately leads to compromise in the integrity of that tissue may be of clinical significance. In addition, continued research into the prevalence of CLL-related organ compromise, risk assessment, and disease progression monitoring is warranted to improve patient outcomes and quality of life.

Ibrutinib, Fludarabine, Cyclophosphamide and Obinutuzumab (iFCG) for Firstline Treatment of Patients with CLL with Mutated IGHV and without Del(17p)/ TP53 Mutation: Six-Year Follow-up Analyses

Background Patients (pts) with IGHV-mutated ( IGHV-M) CLL have favorable long-term outcomes after receiving first-line FCR (fludarabine, cyclophosphamide and rituximab). We designed an investigator-initiated, phase II trial with ibrutinib, fludarabine, cyclophosphamide, and obinutuzumab (iFCG) for previously untreated pts with IGHV-M CLL (NCT02629809), and we report here an updated analysis with a median follow-up of 72 months. Methods Inclusion criteria included diagnosis of previously untreated CLL/SLL needing treatment per iwCLL criteria, age ≥18, IGHV-M, absence of both del(17p) and TP53 mutation. Pts received 3 courses of iFCG. Pts achieving CR/CRi with undetectable MRD (U-MRD) in bone marrow (BM) (4-color flow-cytometry, sensitivity 10 -4) after 3 courses of iFCG received ibrutinib with obinutuzumab (iG) for 3 cycles, followed by ibrutinib monotherapy for 6 months. All other pts received iG for 9 cycles (C4-12). Pts with U-MRD (CR/CRi or PR) at end of Cycle 12 stopped all therapy, including ibrutinib. Response assessment was per 2008 iwCLL criteria with BM and CT scans every 3 months during the first year. After completion of all therapy, pts were followed by clinical examination, blood counts and peripheral blood MRD every 6 months. Results Between March 2016 and August 2018, 45 pts initiated treatment. Data cutoff was July 15, 2023. Baseline characteristics are shown in Table 1. All pts per study inclusion criterion had IGHV-M; however, 1 enrolled pt was later reclassified as IGHV-unmutated. A total of 69% pts had del(13q). After three cycles of iFCG, 39/45 (87%) pts achieved marrow U-MRD. Responses improved with continued therapy with 40/45 (89%) and 41/45 (91%) achieving marrow U-MRD after Cycles 6 and 12, respectively. Overall, 44/45 (98%) pts achieved marrow U-MRD as best response at any time during the study. Median follow-up duration is 72 months. 41/45 pts completed 12 cycles of treatment (4 pts came off study prior to Cycle 12). All 41 pts achieved marrow U-MRD and per protocol, discontinued ibrutinib. After a median follow-up of 61 mos post-discontinuing ibrutinib, 8 pts had MRD recurrence (defined as 2 consecutive values of ≥0.01% in peripheral blood by flow cytometry) at a median of 32 mos (range, 20-67 mos) after stopping all therapy. Of the 8 pts with MRD recurrence, 2 pts had clinical relapse (described below); remaining 6 pts are being monitored with no clinical progression or active therapy. The 6-year PFS and OS are 92.2% (95% CI= 77.7-97.4) and 97.7% (95% CI= 84.9-99.6), respectively. Two pts had clinical progression: one pt had IGHV 3-21; MRD recurred 28 mos after discontinuing ibrutinib, with clinical relapse 59 mos after discontinuing ibrutinib; this pt is now in remission with venetoclax-based therapy; the second pt with clinical relapse had IGHV-unmutated CLL, MRD recurred 24 mos after discontinuing ibrutinib, with clinical relapse 48 mos after discontinuing ibrutinib; this pt has not yet required therapy for relapse. No pt had progression to Richter transformation. One pt developed therapy-related myelodysplastic syndrome; this pt is being monitored for 58+ months without any active therapy for MDS with normal blood counts. One pt died from congestive heart failure during month 9 of the study. Conclusions iFCG regimen with only three cycles of combination chemotherapy achieves U-MRD rates of 98% in bone marrow on an intent-to-treat analysis and a 6-year PFS of 92% in IGHV-M CLL. These results are favorable compared to the 5-year PFS of approximately 65% with FCR (CLL10 trial) for the same genomic subgroup. Additionally, these results also appear favorable to the current targeted therapy regimens (such as BTKi, BCL2i+CD20 antibody) for IGHV-M CLL. With the caveat that the role of chemoimmunotherapy in CLL has significantly declined, the iFCG regimen provides for a very high rate of durable remissions among a chemo-sensitive subgroup of pts with CLL.

A Single Center Real World Study of Outcome and Resistance of Bruton Tyrosine Kinase Inhibitors (BTKi) in Chinese Patients with Chronic Lymphocytic Leukeima/Small Lymphocytic Lymphoma

Introduction Acquired BTK/PLCG2 mutations remain to be the driver of Bruton Tyrosine Kinase inhibitor (BTKi) resistance. But the underlying mechanisms need to be further explored. In this study, we retrospectively analyzed clinical and biological characteristics of BTKi-treated CLL patients and report the outcome and resistance in our center (the First Affiliated Hospital of Nanjing Medical University, Jiangsu Province Hospital). Method 262 patients treated with single BTKis continuously were collected and follow up the outcome in our center. Progression-free survival (PFS) was defined as from BTKi initiation to disease progression on BTKi. Next-generation sequencing (NGS) and High sensitivity droplet digital PCR (ddPCR) acquired at treatment initiation /or at the time of disease progression were used to describe mutational landscape. Kaplan-Meier method and the log-rank test were used for analysis. Results A total of 262 patients were enrolled from January 2014 to March 2023, and the median age was 63 (range 28-88) years. Ibrutinib, Zanubrutinib, Orelabrutinib were administered in 55.3%,18.3% and 17.9% of patients respectively, in addition to 6 patients with Acalabrutinib and one with Loxo-305, among them 47.7% (125/262) received BTKi as first line treatment. With a median follow up of 27.3 months, 208 patients were in durable remission while 54 patients relapsed, the median exposure of BTKi was 26.8 (range, 1-73.8) sand 27.7 (range, 3-69.8) months respectively. The median PFS was 5.8 years (5.0-NA, 95% CI) for the whole cohort. Clinical and biological characteristics of both cohorts at initiation of BTKi treatment were described and compared in Table 1. Higher proportion of bulky disease (50.0% vs 23.5%), IGHV unmutated status (84.3% vs 50.5%), del(17p) (44.7% vs 12.9%), TP53 mutation (37.8% vs 15.2%), TP53 aberrations (62.5% vs 24.3%) and complex karyotype (40.5% vs 21.1%) were shown in the BTKi relapsed cohort as compared to responsive cohort. Inferior PFS was observed in patients with TP53 aberration vs without TP53 aberration ( 45.6 mos vs not reached, p<0.0001), unmutated IGHV vs mutated IGHV (56.2 mos vs not reached, p=0.0005), with del(17p) vs without del(17p) (36.1 mos vs not reached, p<0.0001), with complex karyotype and without complex karyotype (69.8 mos vs not reached, p=0.0401), bulky disease vs no bulky disease (45.6 mos vs 69.8 mos, p=0.0006) and elevated LDH vs normal LDH (66.5 mos vs not reached, p=0.0083). Moreover, patients with del(11q) or BTKi given as second or greater line showed a tendency of inferior PFS ( p= 0.1963, p= 0.0735, respectively). Regarding the relapsed cohort, 43 patients displayed CLL progression while 11 patients displayed Richter transformation (RT, including 1 Hodgkin lymphoma [HL]) , the median time from initiation to progression were 33.7 months and 9.5 months, respectively（p<0.0001). BTK/PLCG2 mutations were the most common mutation at the timepoint of disease progression. By integrating NGS and ddPCR results, 54.9% (28/51) relapsed patients acquired BTK/PLCG2 mutation. BTKC481S mutation was the dominant hotspot mutation in all kinds of BTKi relapsed cases. Other mutations at the C481 site included C481R, C481Y, C481F. However, BTKT474 mutation was only detected in Orelabrutinib-resistant cases (Figure 1). 6 patients presented with multi-hit mutations. Treatment after disease progression on BTKis is still challenging. In our relapsed cohort, the median PFS was 5.7 months and poorer in RT as compared with CLL progression (3.0 months vs 6.7 months, p= 0.0874). Venetoclax-based regimen might be an effective salvage therapy which could showed a benefit trend in PFS as compared to other post BTKi therapy (10.1 months vs 3.1 months, p= 0.1818). Conclusion In our real world study, patients with IGHV unmutated status, TP53 aberrations, bulky disease and elevated LDH showed inferior PFS. Acquired BTK/PLCG2 mutations remained to be key drivers of BTKis resistance and BTKC481S mutation was the dominant mutation, while BTKT474 mutation was only detected in Orelabrutinib-resistant patients. The prognosis was rather poor for relapsed patients especially for RTs, treatment strategy after disease progression remains to be optimized.

Chromosome Banding and SNP-Array Analysis Are Complementary Methods to Characterize Karyotype Complexity in High-Risk Chronic Lymphocytic Leukemia

Introduction: Karyotype complexity is of prognostic significance in chronic lymphocytic leukemia (CLL). It can either be assessed by chromosome banding analysis (CBA) or by chromosome microarray analysis (CMA). How to integrate both methods into CLL diagnostic procedures is not defined. Material and Methods: To compare both methods in their ability to detect chromosomal aberrations, samples from 110 patients enrolled on the CLL2O trial (NCT01392079) were analyzed in parallel by Affymetrix ® 6.0 single nucleotide polymorphism arrays (SNP-arrays, CMA) and CBA (CpG oligonucleotide and IL-2 stimulation). The trial included genetically complex high-risk CLL cases defined by TP53 loss (treatment-naïve or relapsed) or refractoriness to purine-analogue based treatment. Intraindividual reference DNA for paired CMA was available for 79 samples. CMA-defined gains and losses outside known structural variations were counted as aberration irrespective of their size. Discontinuous gains and losses were counted as one aberration whenever segments had a similar log2-ratio. Results: CBA identified 561 chromosomal aberrations with a median of 4 aberrations per case (range: 0-21). With 653 DNA copy number alterations, CMA identified more aberrations partly afforded by a high number of unbalanced translocations (median: 5 aberrations per case, range: 0-19). With regards to karyotype complexity (KC), CBA and CMA allocated 67/110 cases (61%) to comparable risk groups as defined by Baliakas et al. (2019) and Leeksma et al. (2021). CMA assigned more cases to higher complexity risk groups than CBA, which was not observed when excluding gains and losses <5Mb not previously deemed to be significant. However, this approach did not improve the congruency in KC risk group stratification between both methods (see Table). Only 14/110 cases (13%) had a complete overlap in the chromosomes found to be affected by CBA and CMA. Overall, CBA discovered more additionally affected chromosomes than CMA (p=0.0104). Considering all localizable breakpoints of the CBA-defined structural chromosomal changes (N=922), 532 coincided with a cytoband or a cytoband directly adjacent to one harbouring CMA-defined copy number alterations (N=299 and N=233, respectively), whereas 128 CBA-defined breakpoints located to other cytobands on the same chromosome arm (N=85) or on the other arm (N=43). For 50 of these 128 breakpoints the distance between the CBA-identified cytoband and the CMA-defined breakpoint was <20 Mb. About one quarter of CBA-defined breakpoints (N=237, 23%) affected chromosomes not found to be altered in CMA. Potential explanations for non-detection by CMA were small clone sizes (78/237, 33%; considering breakpoints found in <25% of metaphases), association with an ultra-complex karyotype (140/237, 59%; referring to cases with ≥10 affected chromosomes and/or a composite karyotype), and no or poor coverage of cytobands by SNP-array probes (72/237, 30%; referring to cytobands with stretches >1Mb covered by ≤5 probes). Besides, the vast majority of the 237 breakpoints belonged to alterations that can in principle be balanced: 209 translocations, 8 insertions and 2 inversions. Only 18/237 breakpoints defined deletions, 15 of which met at least one of the criteria mentioned above as potential explanations for non-detection by CMA. Overall, 134 chromosomal alterations were detected by CMA alone. Four of these alterations were copy neutral losses of heterozygosity. Most of the 130 DNA copy number alterations were <20 Mb in size (N=104) and 22/130 alterations have previously been associated with a shorter overall survival (affecting 18/110 cases; 16%). Regarding loss of CDKN2A/ B and gain of MYC as genetic features associated with an increased risk for Richter transformation, CMA identified three cases each lacking abnormalities on the respective chromosome in CBA. CBA identified three cases with a potential MYC rearrangement and one case with a potential CDKN2A/ B loss despite having normal results for 9p21 in CMA. Conclusions: In this cohort of high-risk CLL cases, CBA and CMA were complementary methods for karyotype characterization. CBA was more sensitive in uncovering chromosome involvement than CMA, whereas CMA was superior in determining specific DNA copy number alterations previously associated with an inferior prognosis. As to what extend these findings apply to standard-risk CLL cases needs to be investigated.

Co-Expression of C-MYC/BCL2 Is Associated with Inferior Survival Outcomes in Relapsed/Refractory Diffuse Large B-Cell Lymphoma after Autologous Stem Cell Transplantation - a Nationwide Retrospective Analysis in Singapore

Introduction Co-expression of C-MYC and BCL2 in diffuse large b-cell lymphomas (DLBCL), also termed double-expressor lymphomas (DEL), has been shown to be associated with poorer outcomes after standard R-CHOP induction therapy. Approximately 70% of DEL will relapse within 5 years. The subsequent traditional approach with potential for cure has been high dose chemotherapy followed by autologous hematopoietic stem cell transplantation (ASCT). Whilst factors such as remission status after front-line treatment and early relapse have been associated with poorer outcomes after ASCT, data are limited regarding significance of DEL status on survival outcomes post-ASCT. We retrospectively studied the prognostic impact of DEL status on outcomes in patients with relapsed or refractory (R/R) DLBCL who underwent ASCT. Methods This was a retrospective, nationwide study of adults patients, >18 years old, with R/R DLBCL who underwent autologous hematopoietic stem cell transplantation (ASCT) between 2010 and 2022 at the only 2 transplant centers in Singapore - Singapore General Hospital and National University Cancer Institute. Patients with double/triple hit lymphoma, defined as concurrent rearrangements of MYC and BCL2 and/or BCL6 by fluorescence in situ hybridization (FISH) analysis, were not included in this study. Patients with transformed indolent B-cell NHL (non hodgkin lymphoma), primary mediastinal B-cell lymphoma, primary CNS (central nervous system) lymphoma, or Richter transformation of chronic lymphocytic leukemia were excluded. Only patients that had available MYC and BCL-2 immunohistochemistry (IHC) were included in this study. Overall survival (OS) and progression free survival (PFS) were estimated using the Kaplan-Meier method. Cox proportional hazards regression models were used to assess associations between covariates of interest and OS or PFS. Results A total of 72 patients were included, 44 (61.1%) non-double expressor DLBCL (non-DEL) and 28 (38.9%) double expressor DLBCL (DEL). Patient demographics and disease characteristics at relapse were similar in both groups aside from a higher incidence of CNS involvement in the non-DEL group as compared to DEL group, 34.1% vs 10.7% (Table 1). Both groups achieved a >90% response (CR and PR) after second-line salvage chemotherapy as well as a >90% response post-transplant (CR and PR). Patients with DEL however were more likely to relapse post-transplant, 69.7% vs 40.9% (p = 0.032) and were also associated with increased odds of all-cause mortality, 60.7% vs 36.4% (p=0.043). This significance was maintained on multivariable analysis, HR 4.22 95% CI 1.20 - 14.84 (p=0.025) and HR 4.32 95% CI 1.10 - 17.15 (p=0.038) respectively. The median follow up for survivors were 42 months (range, 26 to 64 months) in the DEL patients and 60 months (range, 46 to 88 months) in the non-DEL patients. The 5-year PFS in patients with DEL was inferior to non-DEL patients, 23.3% vs 49.6% respectively, p=0.022. DEL patients were also associated with inferior 5-year OS, 40.2% vs 65.7%, p=0.041. In multivariable model, DEL status remained significantly associated with inferior PFS and OS. We also observed that patients with CNS involvement at relapse had inferior PFS and OS. Male gender and a less than complete metabolic response (CR) status prior to transplant, assessed on PET-CT, was also associated with inferior OS. Conclusion Co-expression of C-MYC/BCL2 was associated with inferior outcomes after ASCT in patients with R/R DLBCL. While ASCT has been the standard curative approach in the R/R setting, considerations for novel targeting therapies to achieve a deeper response prior to transplant or the upfront use of chimeric antigen receptor T-cell therapy at first relapse may be further explored in this high-risk subset of patients.

Targeting BCL2 pathways in CLL: a story of resistance and ingenuity.

Chronic lymphocytic leukemia (CLL) is common amongst leukemic malignancies, prompting dedicated investigation throughout the years. Over the last decade, the treatment for CLL has significantly advanced with agents targeting B-cell lymphoma 2 (BCL2), Bruton's tyrosine kinase, and CD20. Single agents or combinations of these targets have proven efficacy. Unfortunately, resistance to one or multiple of the new treatment targets develops. Our review investigates various mechanisms of resistance to BCL2 inhibitors, including mutations in BCL2, alterations in the Bcl protein pathway, epigenetic modifications, genetic heterogeneity, Richter transformation, and alterations in oxidative phosphorylation. Additionally, the review will discuss potential avenues to overcome this resistance with novel agents such as bispecific antibodies, Bruton's tyrosine kinase (BTK) degraders, non-covalent BTK inhibitors, and chimeric antigen receptor T (CART).

Clinical PD-1/PD-L1 Blockades in Combination Therapies for Lymphomas.

Immunotherapy with the programmed cell death protein 1 (PD-1)/PD-1 ligand (PD-L1) blockade has revolutionized the treatment of advanced solid cancers. However, these clinical benefits have been limited to cases of malignant lymphomas, showing promising results for only classic Hodgkin lymphoma (cHL) and primary mediastinal B-cell lymphoma (PMBCL). To bring clinical benefits to more patients with lymphoma, numerous combination therapies involving PD-1/PD-L1 blockade have been tested in clinical trials in both frontline and relapsed/refractory settings. This article reviews the current landscape of combination therapies with PD-1/PD-L1 blockade for lymphoma and discusses the potential therapeutic approaches. An interim analysis of a phase 3 study demonstrated increased progression-free survival with nivolumab combination therapy over the current frontline treatment in patients with advanced-stage cHL. The results of combination therapies for aggressive B-cell lymphomas, except for PMBCL, have been disappointing. Several clinical trials of combined PD-1/PD-L1 blockade and Bruton's tyrosine kinase inhibitors are exploring its efficacy in patients with chronic lymphocytic leukemia (CLL) with Richter transformation. Several T-cell lymphoma subtypes respond to PD-1/PD-L1 blockade monotherapy. Further clinical trials are underway to investigate appropriate combination regimens with PD-1/PD-L1 blockade, especially for cHL, CLL with Richter transformation, and T-cell lymphoma, in both frontline and relapsed/refractory settings.

Clinical and molecular biological characterization of patients with accelerated chronic lymphocytic leukemia

Objective: To investigate the clinical and molecular biological characteristics of patients with accelerated chronic lymphocytic leukemia (aCLL) . Methods: From January 2020 to October 2022, the data of 13 patients diagnosed with aCLL at The First Affiliated Hospital of Nanjing Medical University were retrospectively analyzed to explore the clinical and molecular biological characteristics of aCLL. Results: The median age of the patients was 54 (35-72) years. Prior to aCLL, five patients received no treatment for CLL/small lymphocytic lymphoma (SLL), while the other patients received treatment, predominantly with BTK inhibitors. The patients were diagnosed with aCLL through pathological confirmation upon disease progression. Six patients exhibited bulky disease (lesions with a maximum diameter ≥5 cm). Positron emission tomography (PET) -computed tomography (CT) images revealed metabolic heterogeneity, both between and within lesions, and the median maximum standardized uptake value (SUVmax) of the lesion with the most elevated metabolic activity was 6.96 (2.51-11.90). Patients with unmutated IGHV CLL accounted for 76.9% (10/13), and the most frequent genetic and molecular aberrations included +12 [3/7 (42.9% ) ], ATM mutation [6/12 (50% ) ], and NOTCH1 mutation [6/12 (50% ) ]. Twelve patients received subsequent treatment. The overall response rate was 91.7%, and the complete response rate was 58.3%. Five patients experienced disease progression, among which two patients developed Richter transformation. Patients with aCLL with KRAS mutation had worse progression-free survival (7.0 month vs 26.3 months, P=0.015) . Conclusion: Patients with aCLL exhibited a clinically aggressive course, often accompanied by unfavorable prognostic factors, including unmutated IGHV, +12, ATM mutation, and NOTCH1 mutation. Patients with CLL/SLL with clinical suspicion of disease progression, especially those with bulky disease and PET-CT SUVmax ≥5, should undergo biopsy at the site of highest metabolic uptake to establish a definitive pathological diagnosis.

NIMG-89. CNS-ISOLATED RICHTER’S TRANSFORMATION: THE FALLIBILITY OF NEURO-IMAGING AND THE CRITICAL ROLE OF BRAIN BIOPSY IN A CHALLENGING DIAGNOSIS

Abstract INTRODUCTION An 81-year-old male was admitted for acute encephalopathy and failure to thrive. Workup revealed a lymphocyte-predominant leukocytosis, prominent axillary and mediastinal lymphadenopathy on CT, and multiple supra-tentorial FLAIR-hyperintense lesions that were homogenously contrast-enhancing. Axillary lymph node biopsy demonstrated small lymphocytic lymphoma (SLL), a variant of CLL. Despite concern for CNS malignancy, brain biopsy was initially deferred since the patient’s brain lesions were attributed to SLL metastasis. However on hospital day 15, he developed partial seizures, prompting stereotactic biopsy which revealed DLBCL. DATA/DISCUSSION Our case highlights the pitfalls of relying solely upon neuro-imaging to diagnose Richter’s transformation (RT) isolated to the CNS. First, MRI does not differentiate CNS metastasis of systemic lymphoma from CNS RT. A review of 35 biopsy or LP-proven cases of CNS-isolated RT showed imaging characteristics consistent with primary and metastatic CNS lymphoma. When parenchymal lesions are present, all are T2/FLAIR hyper-intense; 60% are unifocal (40% multifocal); and 95% homogenously enhance. Second, CNS-isolated RT is at least 3 times rarer than CNS metastases of CLL. Among patients with CLL, ~1% will eventually exhibit CNS metastasis but < 0.3% will develop CNS-isolated RT. In patients with known CLL and no evidence of high-grade transformation, it is reasonable to attribute brain lesions to CNS metastasis of CLL as opposed to RT, absent a definitive tissue diagnosis. CONCLUSION These data emphasize the importance of biopsy in the workup of CNS lymphoma, especially since treatment differs based on histopathological subtype. Given its chronic indolent course, SLL is typically managed expectantly, whereas the aggressive nature of DLBCL warrants more intensive chemotherapy. Our case also shows that in patients with suspicious CNS lesions, presence of systemic malignancy does not eliminate the need for brain biopsy, and that clinical deterioration should prompt biopsy if not already performed.

Cytogenomic features of Richter transformation

BackgroundRichter transformation (RT) is the development of aggressive lymphoma in patients with chronic lymphocytic leukemia (CLL) or small lymphocytic lymphoma (SLL). This rare disease is characterised by dismal prognosis. In recent years, there has been a deeper understanding of RT molecular pathogenesis, and disruptions of apoptosis (TP53) and proliferation (CDKN2A, MYC, NOTCH1) has been described as typical aberrations in RT.ResultsA single-institution cohort of 33 RT patients were investigated by karyotyping, fluorescence in situ hybridization and single nucleotide polymorphism/copy number (CN) arrays. Most of RTs were typically manifested by diffuse large B-cell lymphoma, not otherwise specified, among the remaining cases one was classified as high-grade B-cell lymphoma with 11q aberrations. The most frequent alterations (40–60% of cases) were represented by MYC rearrangement/gain, deletions of TP53 and CDKN2A, IGH rearrangement and 13q14 deletion. Several other frequent lesions included losses of 14q24.1-q32.33, 7q31.33-q36.3, and gain of 5q35.2. Analysis of 13 CLL/SLL-RT pairs showed that RT arised from the CLL/SLL by acquiring of 10 ~ 12 cytogenetic or CN lesions/case, but without acquisition of loss of heterozygosity regions. Our result affirmed the higher genetic complexity in RT than CLL/SLL and confirmed the linear features of RT clonal evolution as predominant.ConclusionsCytogenomic profile was concordant with the literature data, however the role of IGH rearrangement, 14q deletion and 5q35.2 gain need to be explored. We anticipate that further characterization of RT lesions will probably facilitate better understanding of the RT clonal evolution.

Richter transformation – retrospective treatment outcomes analysis in Polish Adult Leukemia Study Group

Richter transformation (RT) is defined as developing an aggressive lymphoma in 2–10% of patients suffering from chronic lymphocytic leukemia (CLL). So far, no complex analysis of RT demographics and treatment outcomes has been performed in Poland. Thus, the retrospective analysis of 124 patients with RT from Polish hematology centers was designed. Ninety-nine patients with diffuse large B-cell lymphoma (DLBCL-RT) were identified. The median overall survival (OS) for DLBCL-RT was 17.3 months, while for Hodgkin lymphoma (HL-RT)-21.3 months. In multivariate analysis, the independent factors of worse OS for DLBCL-RT were: prior CLL therapy, ECOG stage ≥2, and elevated serum LDH activity. Patients who proceeded to hematopoietic stem cell transplantation (HSCT) achieved better results. The median OS in allogeneic HSCT recipients was not reached, while in autologous HSCT median OS was 51.3 months. In conclusion, our study represents the largest dataset of patients diagnosed with RT in Poland and confirms its dismal prognosis.

Outcomes of Patients with Richter Transformation without Prior Chemoimmunotherapy for CLL/SLL: An International Multicenter Retrospective Study

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.

Pirtobrutinib in Richter Transformation: Updated Efficacy and Safety Results with 18-Month Median Survival Follow-up from the Phase 1/2 BRUIN Study

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.

Anti-CD19 Chimeric Antigen Receptor T-Cell Therapy for Richter's Transformation: An International Multicenter Retrospective Study

Background: Aggressive lymphoma, most commonly large B-cell lymphoma (LBCL), arising in the setting of chronic lymphocytic leukemia (CLL) is known as Richter's transformation (RT), and is associated with poor outcomes. CD19 CART has revolutionized the treatment (tx) of LBCL, with durable responses for patients (pts) with relapsed/refractory disease. Pts with RT have been excluded from most major CD19 CART trials. Therefore, there is limited data describing outcomes of pts with RT receiving CD19 CART Methods: We conducted an international multicenter retrospective study of pts with RT who received CD19 CART approved for hematologic malignancies at 9 academic centers. RT was defined as pts with LBCL with preceding or concurrently diagnosed CLL. We collected pt, disease, and tx characteristics. Progression-free survival (PFS) and overall survival (OS) were measured from date of CD19 CART infusion and estimated using the Kaplan-Meier method. Cox regression model was used to associate prognostic factors with PFS and OS. Response was assessed by Lugano criteria. Results: 62 pts were included. Median age at CD19 CART infusion was 65 (range: 27-80). Median prior lines of therapy for CLL or RT were both 2 (CLL range: 0-10, RT range: 0-7). 52 (84%) pts previously received a Bruton tyrosine kinase inhibitor (BTKi) or BCL2 inhibitor (BCL2i) for CLL or RT. Median Ki-67 on pathology sample was 80% (range: 40-100), median SUV on brightest lymph node (LN) on PET-CT was 15.0 (range: 3-50.6), median size of largest LN was 3.8cm (range: 0-16), and median LDH prior to CD19 CART was 244 (range: 96-2878, ULN range: 190-271). Median time from apheresis to CD19 CART infusion was 33 days (range: 24-100), and 52 (84%) pts received bridging therapy. 40 (65%), 14 (23%), 7 (11%), and 1 (2%) pts received axicabtagene ciloleucel (axi-cel), tisagenlecleucel (tisa-cel), lisocabtagene maraleucel (liso-cel), and brexucabtagene autoleucel (brexu-cel), respectively. Overall response rate was 65%, with 29 (47%) and 11 (18%) pts attaining complete response (CR) and partial response (PR), respectively. After a median follow up of 24.1 months (mos) from CD19 CART infusion, the median PFS was 4.7 mos (95% CI: 2.3-6.9), and median OS was 8.5 mos (95% CI: 5.1-32.5) (Figure). Median duration of response was 14.5 mos (95% CI: 4.0-NR), with a median not reached (NR) (95% CI: 13.1-NR) for pts who achieved a CR, and a median of 2.3 mos (95% CI: 1.0-3.3) for pts who achieved a PR. Among 39 pts who died, 28 (72%) died due to progression of disease (PD), and 11 (28%) died for other reasons including 8 infections (4 COVID), 1 septic shock, 1 stroke, and 1 respiratory failure. The cumulative incidence of non-relapse mortality at 12 mos was 13% (95% CI: 6.2-23.4). 3 pts in a CR underwent allogeneic stem cell transplantation, 2 were alive at last known follow up (3.9 and 24.2 mos post-transplant), and 1 pt died from PD 21 mos post-transplant. 55 (89%) pts had CRS, with 9 (15%) grade ≥3 events. 43 (69%) pts had ICANS, with 23 (38%) grade ≥3 events. On univariable analysis, increasing Ki-67 and LDH were found to be associated with worse PFS and OS, and attaining a CR with CD19 CART was found to be associated with improved PFS and OS. On multivariable analysis, increasing Ki-67 and LDH, and greater number of prior lines of therapy for RT were independent prognostic variables for worse PFS and OS, and attaining a CR was associated with improved OS. All other variables, including type of CD19 CART product received, were not correlated with PFS or OS (Table). Conclusions: We report findings from the largest cohort of pts with RT who received CD19 CART. Of note, 84% of pts were exposed to either BTKi or BCL2i for the tx of CLL or RT. RT remains a disease of unmet need, as the median OS was 8.5 mos in this study. However, there is some progress made as historically the median OS for patients with RT previously treated with BTKi is 4 mos (Kittai et al AJH 2023). Given higher number of prior therapies is associated with worse OS, earlier use of CD19 CART in the RT disease course may be warranted. Our data support the use of CD19 CART for pts with RT, with durable disease control in a subset of pts, however there is clear room to improve and develop better therapies. Given observed high response rate to CD19 CART, along with most pts experiencing early relapse, allogeneic stem cell transplantation at response should be considered. Prospective clinical trials evaluating CD19 CART with novel agents for RT are currently ongoing.

Multicenter Study to Assess the Outcomes and Prognosis of Richter's Transformation in the Era of Novel Agents and Cell Therapy

INTRODUCTION: Richter's transformation (RT) is the transformation of chronic lymphocytic leukemia or small lymphocytic lymphoma (CLL/SLL) into an aggressive lymphoma, most commonly diffuse large B-cell lymphoma (DLBCL). RT occurs in 2-10% of CLL patients, usually between 2-5 years after CLL diagnosis. The prognosis of RT is poor and the historical median overall survival (OS) after diagnosis is about 8-14 months. However, with the development of novel therapeutic agents including Bruton tyrosine kinase inhibitors (BTKi) and anti-CD19 CAR T-cell therapy, the natural history and prognosis of RT have evolved. To date there is limited data on the prognosis and management of RT in the era of novel therapies. To better understand the prognosis, impact of new therapeutics, and survival for RT in the modern era we performed a multicenter retrospective study to assess the outcomes of RT. METHODS: We performed a multicenter retrospective study including 4 US centers evaluating patients who were diagnosed with RT between 2012-2022 with the current analysis limited to those patients with large B-cell lymphoma transformation. Statistical analyses include descriptive statistics, t-tests for normally distributed continuous variables, non-parametric tests for skewed variables, and chi-square for categorical variables. Overall survival (OS) was calculated using Kaplan-Meier estimates. RESULTS: We analyzed 78 patients with DLBCL transformation from underlying CLL. The median age at RT diagnosis was 66 years (43-84 years). Most patients had advanced stage III-IV disease 92% (n=72). Extranodal disease was present in 68% (n=53). Among 31 patients with 17p deletion or p53 mutational data available at the time of CLL diagnosis, one of these findings was present in 18 patients. Patients had 2 median lines (range 0-7) of treatment for CLL prior to RT diagnosis. 49% (n=38) had BTKi exposure and 28% (n=22) had Venetoclax exposure before RT diagnosis. 24% (n=19) had no prior treatment for CLL before RT. The median time from CLL to RT diagnosis was 42.5 (0-332) months. Median lines of therapy for RT were 2 (range 1-8). The most common frontline regimens for RT included R-CHOP/ R-CHOP-like backbone in 58% (n=45) or high intensity chemoimmunotherapy regimens (R-EPOCH/CVAD) in 14% (n=11). Overall response rate (ORR) to frontline treatment was 56% (complete response (CR)=32/partial response (PR)=12). Of the patients who received 1 st line treatment and achieved a CR/PR (n=44), the 1-year duration of response (DOR) was 50% and the median DOR was 14 months. Fifty-one patients either relapsed or had refractory/progressive disease after frontline treatment and 48 patients received further treatment. Among these 48 patients, 29% (n=14) received a covalent or a non-covalent BTKi in the 2 nd or higher line setting, with an ORR of 43% (CR=4, PR=2). 23% (n=11) received venetoclax with/without other agents in the 2 nd or higher line setting, with an ORR of 36% (CR=3, PR=1). In total, 17 patients received CD19 based CAR T-cell therapy as part of treatment for RT, all in a second or later line of treatment. The ORR and CR rate to this therapy was 82% (n=14). Of these 14 responding patients, the 1-year DOR was 57% and the median DOR was not reached. 12 patients underwent allogeneic transplant (alloHCT), 11/12 as a consolidative treatment option. At first disease assessment after allo-HCT, the ORR was 92% (CR=11). Of the 11 responders, the 1-year DOR was 73% and the median DOR was 42 months. For the entire cohort (n=78), the 1-year OS was 62% and the median OS was 31 months (95% CI 22-NR), which suggest improvement compared to historical reports. CONCLUSION Although RT has a poor prognosis, with the use of novel therapies such as BTKi and CAR T-cell therapy, the overall survival of these patients has improved in the current era. The overall response to chemoimmunotherapy in the first line setting remains poor. Despite this, advances in the management of RT with incorporation of targeted and cellular therapies has improved clinical outcomes of RT. Incorporating these agents either alone or in combination with chemoimmunotherapy in the earlier setting may further improve outcomes in patients with this aggressive disease.