Richter's Transformation Research Articles

PB1863: BRUIN CLL-322: A PHASE 3 OPEN-LABEL, RANDOMIZED STUDY OF FIXED DURATION PIRTOBRUTINIB+VENETOCLAX AND RITUXIMAB VS VENETOCLAX AND RITUXIMAB IN PREVIOUSLY TREATED CLL/SLL (TRIAL IN PROGRESS)

Background: Covalent Bruton’s Tyrosine Kinase (BTK) inhibitors (BTKi) have transformed the management of chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL), but these treatments are not curative and the majority of patients will require additional treatment. The MURANO study established the time-limited combination of 2 years venetoclax plus rituximab as a clinically important regimen for patients with R/R CLL/SLL. However, that trial almost exclusively enrolled patients who were never treated with a covalent BTKi, a population less relevant in the context of today’s standard of care. Aims: Pirtobrutinib is a highly selective, non-covalent BTKi that inhibits both wild type (WT) and C481-mutated BTK with equal low nM potency. In a phase 1/2 BRUIN trial, pirtobrutinib achieved pharmacokinetic exposures that exceeded its BTK IC96 at trough, was well tolerated, and demonstrated promising efficacy in CLL/SLL patients regardless of prior therapy, number of prior lines of therapy, or BTK C481 mutation status. Therefore, adding fixed duration pirtobrutinib to the time-limited MURANO regimen may allow for even deeper and more prolonged disease control, and generate a clinically relevant dataset in a BTK-pretreated CLL/SLL population. Methods: BRUIN CLL-322 is a randomized, open-label, global phase 3 study comparing fixed duration pirtobrutinib plus venetoclax and rituximab (PVR) versus venetoclax and rituximab (VR) in patients with CLL/SLL who have received prior therapy. To ensure relevance in the modern therapy context, a minimum of 80% of patients must have had a prior covalent BTKi. Approximately 600 patients will be randomized 1:1. Randomization will be stratified by 17p deletion (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 with a diagnosis of CLL/SLL and requirement for therapy per iwCLL 2018 criteria who have received prior therapy that may or may not include a covalent BTKi. Unlimited number of lines of prior therapy are allowed. Key exclusion criteria include CNS involvement by CLL/SLL, Richter transformation at any time pre-enrollment, history of allogeneic stem cell transplant (SCT) or autologous SCT or chimeric antigen receptor (CAR) T-cell therapy within 60 days and prior therapy with a BCL2 inhibitor or non-covalent BTKi. The primary endpoint is progression-free survival (PFS) per iwCLL assessed by an independent review committee. Secondary endpoints include overall response rate (ORR), overall survival (OS), time to next treatment (TTNT), event-free survival (EFS), safety and tolerability, and patient-reported outcomes. This global study is currently enrolling patients (NCT04965493). Results: This study is a Trial in Progress. The results will be presented at a later date. Summary/Conclusion: This study is a Trial in Progress. The conclusions will be presented at a later date.

S149: LONG TERM OUTCOMES OF IFCG REGIMEN FOR FIRSTLINE TREATMENT OF PATIENTS WITH CLL WITH MUTATED IGHV AND WITHOUT DEL(17P)/TP53 MUTATION

Background: Chemoimmunotherapy with FCR has been an effective treatment for patients (pts) with CLL. Pts with mutated IGHV (IGHV-M) have favorable long-term outcomes after receiving FCR. We designed an investigator-initiated, phase 2 trial with ibrutinib, fludarabine, cyclophosphamide, and obinutuzumab (iFCG) for previously untreated pts with IGHV-M CLL (NCT02629809). We report here long-term outcomes with a median follow-up of 56.8 months. Aims: Investigate the role of combined chemoimmunotherapy and targeted therapy in CLL. Methods: Eligibility included age ≥18, IGHV-M, no del(17p)/TP53 mutation. Pts received 3 courses of iFCG. Pts achieving CR/CRi with undetectable MRD (U-MRD) in bone marrow (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 marrow U-MRD at end of Cycle 12 stop all therapy. 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 exam, blood counts and peripheral blood MRD every 6 months. NGS MRD (sensitivity 10-6) was performed in bone marrow in pts with available samples. Results: 45 pts initiated treatment. Median age was 60 [range, 25-71]. 69% 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. The 5-year PFS and OS are 97.7% (95% CI 94–100%) and 97.8% (95% CI 94–100%), respectively. No pt had CLL progression or Richter transformation. One pt developed therapy-related MDS; this pt is being monitored for 38+ months without any therapy for MDS with normal blood counts. The sole event noted on both the PFS and OS curve is a pt death from heart failure. 41/45 pts completed 12 cycles of treatment (4 pts came off study prior to C12). All 41 pts achieved marrow U-MRD4 by flow-cytometry and per protocol, all 41 pts discontinued ibrutinib. After a median follow-up of 44.2 mos post-discontinuing ibrutinib, 6 pts had an MRD recurrence (defined as 2 consecutive values of ≥0.01% in peripheral blood by flow cytometry) at a median of 27.2 mos (range, 20.7-49.0 mos) after stopping all therapy. All 6 pts are being monitored with no clinical progression or active therapy; notably, all 6 pts were MRD+ at 10-6 by marrow NGS after the completion of 3 cycles of iFCG and 4/5 (1 missed sample) were MRD+ at 10-6 by marrow NGS after the completion of Cycle 12. Of the 16 pts who were marrow NGS MRD+ at 10-6 after 3 cycles of iFCG, 6/16 had an MRD recurrence in blood in follow-up vs. 0/20 who were NGS MRD negative/indeterminate (p = 0.004). Of the 12 pts who were marrow NGS MRD+ at 10-6 after Cycle 12, 4/12 had an MRD recurrence in blood in follow-up vs. 1/26 who were NGS MRD negative/indeterminate (p = 0.02). Image:Summary/Conclusion: The iFCG regimen, using only 3 cycles of chemotherapy (as opposed to 6 cycles of chemoimmunotherapy) achieves a very high rate of U-MRD in previously-untreated pts with CLL with IGHV-M CLL. No pt had disease progression with a median follow-up of close to 5 years. The 5-year PFS is 97.7%; this is favorable compared to 5-year PFS of ≈65% with FCR (CLL10), ≈70% with ibrutinib (A041202 trial), and 81% with ibrutinib (RESONATE-2) for IGHV-M CLL. Not unexpectedly, MRD recurrence during follow-up correlated with MRD positivity by NGS during therapy.

P682: NEMTABRUTINIB (MK-1026), A NON-COVALENT INHIBITOR OF WILD-TYPE AND C481S MUTATED BRUTON TYROSINE KINASE FOR B-CELL MALIGNANCIES: EFFICACY AND SAFETY OF THE PHASE 2 DOSE-EXPANSION BELLWAVE-001 STUDY

Background: For patients (pts) with chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) and certain B-cell neoplasms, resistance to Bruton tyrosine kinase inhibitors (BTKi) develops primarily through mutations at the cysteine binding site (C481) or PLCγ2 mutations. Nemtabrutinib (MK-1026, formerly ARQ-531) is a non-covalent, potent inhibitor of both wild type and C481-mutated BTK. Aims: In the phase 1/2 dose-escalation and dose-expansion BELLWAVE-001 study (NCT03162536), the preliminary recommended phase 2 dose (RP2D) of nemtabrutinib was determined to be 65 mg once daily. The efficacy and safety of nemtabrutinib in patients (pts) with CLL/SLL and B-cell non-Hodgkin lymphoma (NHL) were also evaluated at a higher dose during the dose-expansion phase. Methods: In this open-label, single-arm phase 2 study, 9 expansion cohorts were initiated following determination of preliminary nemtabrutinib RP2D. Approximately 10-25 eligible pts were enrolled into Cohort A (relapsed/refractory (r/r) CLL/SLL, with ≥2 prior therapies including covalent BTKi, with documented C481 mutation), Cohort B (r/r CLL/SLL progressed on/intolerant to a BTKi, with ≥2 prior therapies without C481 mutation), Cohort C (Richter transformation with ≥1 prior therapy), Cohort D-H (follicular lymphoma, mantle cell lymphoma, marginal zone lymphoma, high-grade B cell lymphoma with known MYC, BCL-2 or BCL-6 translocations, and Waldenström macroglobulinemia [WM], respectively, who received ≥2 prior therapies), Cohort I (food-effect cohort including pts with B-cell NHL, CLL/SLL, and WM). Primary end point was ORR (per iwCLL criteria, by investigator) for participants with CLL/SLL. Secondary end points included DOR and safety and tolerability. Results: Among 118 pts enrolled, 44 had B-cell NHL, 68 CLL/SLL, and 4 WM. Of these, 94 (79.6%) were treated at the preliminary RP2D, including 51 (54.3%) participants with CLL/SLL. Pts with CLL/SLL had a median (range) number of prior therapies of 4 (1-18), 43 (84%) had prior BTKi therapy, 12 (23%) had del17p, 30 (59%) had IGHV unmutated status, and 32 (63%) had C481S BTK mutation. At data cut-off (April 7, 2021), median (range) follow-up was 4.6 mo (0.1-26.7) for all treated pts. ORR was 57.9% (22/38; 1 CR, 21 PR/PRL) per iwCLL criteria in the efficacy-evaluable population of pts with CLL/SLL treated at preliminary RP2D. Median duration of response was not estimable [NE] (range, 8.3 mo-NE). Among all treated participants, 114 (97%) had a treatment-emergent adverse event (TEAE), with 78 (66%) having a drug-related TEAE, and 9 (8%) having a drug-related TEAE that led to discontinuation. Common TEAEs (≥ 20%) included fatigue (33%), constipation (31%), dysgeusia (28%), cough (25%), nausea (25%), pyrexia (25%), dizziness (23%), hypertension (23%), peripheral edema (22%), diarrhea (21%), and arthralgia (20%). Grade ≥3 TEAEs occurred in 80 (68%) participants. Grade 5 TEAEs occurred in 7 (6%) participants and included death following disease progression 3 (3%), sepsis 1 (1%), dyspnea 1 (1%), and respiratory failure 2 (2%). Common drug-related TEAEs (≥10%) included dysgeusia (15%), nausea (11%), fatigue (11%), and decreased neutrophil count (10%). Grade 3-4 drug-related TEAEs occurred in 31 (26%) participants. No drug-related TEAEs led to death. Summary/Conclusion: Nemtabrutinib has promising antitumor activity with a manageable safety profile in pts with CLL/SLL exposed to multiple lines of therapy, including in those who had progression of disease on prior covalent BTKi. Further evaluation of nemtabrutinib in B-cell malignancies is ongoing.

S146: VENETOCLAX IN PATIENTS WITH CHRONIC LYMPHOCYTIC LEUKEMIA WITH 17P DELETION: 6-YEAR FOLLOW-UP AND GENOMIC ANALYSES IN A PIVOTAL PHASE 2 TRIAL

Background: Patients (pts) with chronic lymphocytic leukemia (CLL) with del(17p) and/or mutated TP53 have adverse prognosis and are a population of interest for improving outcomes. In a pivotal Phase 2 study (NCT01889186) evaluating venetoclax (Ven; a selective oral BCL2 inhibitor) monotherapy in del(17p) CLL (N=158), overall response rate (ORR) was 77% (median time on study, 26.6 mo; Stilgenbauer. J Clin Oncol. 2018;17:1973). Aims: To report final analyses after 5 y from last pt enrolled, including post-hoc subgroup analyses of prognostic markers. Methods: Adults with R/R or previously untreated del(17p) CLL received Ven 400 mg (via ramp-up) orally daily until progressive disease (PD) or intolerance. Main cohort comprised pts with R/R CLL; safety expansion cohort included pts with R/R or untreated CLL. Primary endpoints were ORR (main) and safety (safety expansion). Peripheral blood (PB) and bone marrow (BM) were analyzed pre-Ven for somatic mutations via targeted next-generation sequencing (NGS). Minimal residual disease (MRD) was assessed by flow cytometry, ASO-PCR, and/or clonoSEQ NGS; undetectable MRD (uMRD) is reported at <10−4. Results: In all, 158 pts received Ven (main, n=107; safety expansion, n=51). Data cutoff was 15 December 2020. Pts had median 2 (range, 0−10) prior lines of therapy (LOT); 5 had untreated CLL (first-line [1L]). Common mutations (n/N) were TP53 (113/138 [82%]; 35/113 [31%] had >1), SF3B1 (28/137 [20%]) NOTCH1 (22/137 [16%]), ATM (11/120 [9%]), and BIRC3 (6/120 [5%]); 93/115 (81%) had unmutated IGHV and 118/158 (75%) had ≥20% del(17p). Median time on Ven was 27.4 (range, 0–79.3) mo. At study close, 77 pts were alive; 26 remained on Ven. No new safety signals were observed. With 70 mo median follow-up (f/u), investigator-assessed ORR was 77% (95% CI, 70−84); 21% achieved complete remission (CR)/CR with incomplete blood count recovery (CRi). Median duration of response was 39.3 mo (95% CI, 31.1−50.5); 28% had ongoing response at 60 mo. Of 61 evaluable pts with a PB MRD assessment, 25% had uMRD at ~2 y (24−30 mo). Median progression-free survival (mPFS) was 28.2 mo (95% CI, 23.4−37.6; Figure). Median overall survival (mOS) was 62.5 mo (95% CI, 51.7−NR; 5-y PFS and OS rates, 24% and 52%). Of 5 1L pts, 4 were alive and progression-free. In pts with CR/CRi (n=37), mPFS was 62.2 mo (95% CI, 53.1−NR); in pts with partial remission (PR)/nodular PR (n=85), mPFS was 27.6 mo (95% CI, 22.8−38.0). Overall, 98/158 (62%) pts had PD, including 24/158 (15%) with Richter transformation. Of pts with PD (n=98) or whose disease was refractory to Ven (n=11), 73 received another LOT, most commonly ibrutinib (n=41); mOS from ibrutinib initiation was 28.0 mo. In pts with both del(17p) and TP53 mutation (n=111) vs those with either (n=19), ORR was 75% vs 79%; mPFS was 27.4 vs 22.8 mo (P=.8). In pts with mutated (n=22) vs unmutated IGHV (n=93), mPFS was 40.4 vs 26.9 mo (P=.11). No significant difference in ORR, PFS, or OS was observed in pts with vs without ≥20% del(17p), >1 TP53 mutation, NOTCH1, ATM, or BIRC3 mutations; mPFS was shorter in pts with mutated SF3B1 (n=28) vs without (n=109; 16.4 vs 30.2 mo [P=.0071]). Multivariate analysis is ongoing. Image:Summary/Conclusion: At end of study (median f/u, 70 mo), 48% of pts were alive, 24% were progression-free, and 16% remained on Ven, confirming the long-term activity of Ven in this high-risk population with del(17p) CLL and median 2 prior LOT. Except SF3B1 mutation, other adverse features (eg, >1 TP53 mutation, NOTCH1 mutations, unmutated IGHV) did not influence outcomes with Ven treatment in this cohort.

P1221: DIFFUSE LARGE B-CELL LYMPHOMA RICHTER SYNDROME IN CHRONIC LYMPHOCYTIC LEUKEMIA – A RETROSPECTIVE ANALYSIS OF TREATMENT OUTCOMES IN POLISH ADULT LEUKEMIA STUDY GROUP

Background: Richter syndrome (RS) is a recognized uncommon manifestation and evolution of chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) with a dismal prognosis. It occurs in 2-10% of CLL patients. It is associated with a clonal evolution and progression, generally with a transformation of the original CLL clone to diffuse large B-cell lymphoma (DLBCL) or, less frequently, to Hodgkin Lymphoma (HL). Despite the advances in understanding pathogenesis of the disease, the DLBCL variant of RS (DLBCL-RS) is associated with a dismal prognosis with a median survival < 1 year. The treatment options and risk factors of worse outcome for RS still need to be further expanded. Aims: To study the characteristic and treatment outcomes of patients with DLBCL-RS. Methods: The retrospective analysis of 99 patients diagnosed with DLBCL-RS treated in hematology centers of the Polish Adult Leukemia Study Group (PALG) between 2011 and 2021. Results: Clinical data of 124 patients with Richter syndrome was collected. Ninety-nine patients were diagnosed with DLBCL-RS (79.8%) and further analyzed. Median time since CLL diagnosis to Richter transformation was 43.0 months (range 0-252.0). At the time of transformation 31.3% patients had CLL Rai stage IV, 74.7% were ECOG< 2, while the median Cumulative Illness Rating Scale (CIRS) was 4 (range 0-16). Thirty-seven patients transformed during CLL treatment, 56.7% of them were receiving novel agents (Brutons tyrosine kinase inhibitor or BCL2 inhibitor). Median time of observation after transformation was 10.7 months (range 0-98.6). Median overall survival (OS) after DLBCL-RS diagnosis was 17.3 months (95% Cl 11.9-46.8) and median progression-free survival (PFS) 13.5 months (95% Cl 9.6-22.7). Seventy-six patients (76.8%) had RS treated with intensive chemotherapy protocols, mainly R-CHOP-like regimens for the first line treatment. Only 42.3% had response to the treatment (25/76 complete responses and 11/76 partial responses). Worth mentioning is that in the group of patients with response two patients had ibrutinib monotherapy and one had rituximab-ibrutinib. In forty patients RS was primarily resistant to administered treatment and 65% of them died due to progression or treatment related complications. In the primary resistant DLBCL-RS p53 pathway aberration was noted in 47.5% of patients (17p deletion in 13 patients or TP53 mutation in 6 patients). Better results were achieved for patients who proceeded to autologous hematopoietic stem cell transplantation (auto-HSCT; n=8) and allogeneic HSCT (allo-HSCT; n=10). The median OS in auto-HSCT recipients was 46.1 months, while in allo-HSCT the median OS reached 18.3 months (3 patients died due to allo-HCST-related complications). Significantly lower OS (3.4 months, 95% Cl 14.13-not reached) was observed for RS in heavily pretreated CLL patients (>3 lines of therapy preceding transformation) compared to those treated with up to 3 lines of therapy (23.7 months) (p=0.0002). Median OS for treatment naïve patients at DLBCL-RS diagnosis was not reached. Other factors identified as predictors of poor OS in univariate analysis were ECOG ≥2 (p=0.0014), hemoglobin level <10 g/dl (p=0.017) and platelet count <100x109/L (p=0.0065). Summary/Conclusion: Our study represents the largest dataset of DLBCL-RS patients in Polish hematology centers and confirms the poor outcomes and prognosis associated with RS. The worst treatment results were observed in RS receiving >3 lines of CLL therapy preceding transformation. Only proceeding to hematopoietic stem cell transplantation may improve the prognosis.

P677: CLINICAL EFFICACY AND TOLERABILITY OF VENETOCLAX PLUS RITUXIMAB IN RELAPSED OR REFRACTORY CHRONIC LYMPHOCYTIC LEUKEMIA – REAL WORLD ANALYSIS OF POLISH ADULT LEUKEMIA STUDY GROUP

Background: The introduction of venetoclax into clinical practice has improved the outcome of patients with relapsed/refractory chronic lymphocytic leukemia (RR-CLL). The results of the MURANO trial published in March 2018 showed significantly longer progression-free survival (PFS) and overall survival (OS) in RR-CLL patients treated with venetoclax and rituximab (VEN-R) comparing to bendamustine and rituximab (BR) and resulted in the approval of VEN-R in the therapy of RR-CLL in the European Union and the United States. It should be noted that the results of registration studies often do not correspond with the data from real-life observations. Aims: To study the clinical efficacy and safety profile of VEN-R treatment in RR-CLL patients outside clinical trials. Methods: We performed retrospective analysis of RR-CLL patients treated with VEN-R in hematology centers of the Polish Adult Leukemia Study Group (PALG) from 2019 to 2021. Results: Clinical data of 117 RR-CLL patients treated with VEN-R were collected. Median patient age upon initiation of VEN-R therapy was 67 years (range 33 – 84 years). Seventy-two patients (61.5%) were men. Median Cumulative Illness Rating Scale (CIRS) was 6 (range 2 - 16). Patients were treated with a median of 2 (range 1–9) previous lines of therapy, whereas 32 patients (27.4%) had relapsed following the first line of treatment. Overall, 25 patients (21.4%) had 17p deletion, whereas TP53 mutation was identified in 13 patients (11.1%). The median follow-up was 9.96 months (range 0.27 - 29.13). The overall response rate (ORR) was 95.2%. Seventeen patients (14.5%) achieved complete remission (CR), 83 (70.9%) partial remission (PR), while in 5 patients (4.3%) disease progression was noted. In the patients with 17p deletion (n=22) or TP53 mutation (n=11), CR and PR were observed in 4 (12.1%) and 29 (87.9%) patients, respectively. The median PFS in the whole cohort was 20.8 (95% CI 18.43 - not reached) months and the median OS was not reached. In our study none of the analyzed clinico-pathological factors had significant impact on ORR, PFS and OS. During the follow-up time four (3.4%) cases of Richter transformation were diagnosed. There were 18 deaths recorded during the course of observation; 3 (16.7%) due to disease progression and 7 (38.9%) due to COVID-19 infection. The others were due to infections other than SARS-CoV-2 (n=3, 16.7%) and the cause of death could not be specified in five cases (27.8%). Eighty-three patients (70.9%) remain on treatment, while treatment was discontinued in thirty-four cases (29.1%). Reasons for therapy discontinuation included patient’s death (52.9%), treatment-related cytopenias (17.6%), disease progression (14.7%), Richter’s transformation (11.8%), autoimmune hemolytic anemia (5.9%), diarrhea (2.9%) and infections (8.8%). In one case treatment discontinuation was due to consent withdrawal and one patient was lost to follow-up. The following adverse events of VEN-R treatment were reported during the study: all grade neutropenia (71.8% with grade 3/4 in 55.6%), anemia (51.3%), thrombocytopenia (47%), pneumonia (9.4%), neutropenic fever (6.8%), autoimmune hemolytic anemia (4.3%), immune thrombocytopenic purpura (1.7%), diarrhea (4.3%) and in one case exacerbation of heart failure was observed. Summary/Conclusion: In this retrospective analysis the outcomes of treatment with the VEN-R regimen in real-life setting were worse than those reported in the MURANO trial.

Abstract 3795: Early seeding of Richter transformation in chronic lymphocytic leukemia

Abstract Introduction: Clonal evolution drives cancer development due to the emergence and/or selection of proliferatively advantageous subclones. Its understanding may facilitate the design of anticipation-based management strategies. Richter transformation (RT) is a paradigmatic tumor evolution in which chronic lymphocytic leukemia (CLL), an indolent neoplasia of mature B-cells, transforms into a high-grade lymphoma, usually diffuse large B-cell lymphoma (DLBCL), conferring a dismal prognosis. The evolutionary trajectories of RT and its driving (epi)genomic mechanisms remain largely unknown. Aims: To reconstruct the evolutionary history of RT and to reveal the molecular processes underlying this transformation. Methods: We characterized the whole genome (WGS), epigenome (DNA methylation, H3K27ac, ATAC-seq), and transcriptome (RNA-seq), combined with single-cell DNA and RNA sequencing analyses, of 19 CLL patients developing RT before (n=3) or after treatment with chemoimmunotherapy (n=6) and targeted therapies (BCR or BCL2 inhibitors, n=10). We analyzed 54 longitudinal samples covering up to 19 years of disease course. Results: Our WGS analyses uncovered that RT is characterized by a remarkable structural complexity. We also identified a novel treatment-independent RT-specific mutational process, which we named SBS-RT. The genetic driver landscape of RT is a compendium of alterations in genes involved in cell cycle, MYC, and NF-κB pathways, frequently targeted in single catastrophic events including chromothripsis and chromoplexy. The WGS-based phylogenic reconstruction and single-cell DNA/RNA-seq analyses identified a very early diversification of CLL leading to emergence of RT-cells carrying specific genetic drivers and transcriptomic profiles of RT already at CLL diagnosis. These small subclones were dormant for 6-19 years until rapid expansion associated with the clinical transformation. While the DNA methylome kept track of the cell of origin and proliferative history of RT cells, their chromatin configuration and transcriptional program converged into the overexpression of cell cycle regulators, Toll-like receptors, MYC, MTORC1, and OXPHOS related transcripts, as well as downregulation of BCR pathway. This phenotypic shift was related to de novo activation of key transcription factors. In vitro experiments confirmed that RT cells have a 4-fold higher oxygen consumption at routine respiration and electron transfer system capacity compared to CLL. The resistance of RT to BCR inhibition is consistent with its high OXPHOS and low BCR signaling, which mimics de novo DLBCL-OXPHOS insensitive to BCR inhibition. This OXPHOShigh-BCRlow transcriptional axis of RT can be exploited therapeutically. Conclusions: These findings demonstrate the early seeding of subclones driving advanced stages of cancer evolution and uncover therapeutic targets for the, once expanded, lethal Richter transformation. Citation Format: Ferran Nadeu, Romina Royo, Ramon Massoni-Badosa, Beatriz Garcia-Torre, Martí Duran-Ferrer, Kevin J. Dawson, Marta Kulis, Ander Diaz-Navarro, Neus Villamor, Juan L. Melero, Vicente Chapaprieta, Ana Dueso-Barroso, Julio Delgado, Riccardo Moia, Sara Ruiz-Gil, Domenica Marchese, Núria Verdaguer-Dot, Mónica Romo, Maria Rozman, Gerard Frigola, Alfredo Rivas-Delgado, Tycho Baumann, Miguel Alcoceba, Marcos González, Fina Climent, Pau Abrisqueta, Josep Castellví, Francesc Bosch, Marta Aymerich, Anna Enjuanes, Sílvia Ruiz-Gaspà, Armando López-Guillermo, Pedro Jares, Sílvia Beà, Dolors Colomer, Núria López-Bigas, Josep LlGelpí, David Torrents, Peter J. Campbell, Ivo Gut, Pablo M. Garcia-Roves, Davide Rossi, Gianluca Gaidano, Xose S. Puente, Holger Heyn, Francesco Maura, José I. Martín-Subero, Elías Campo. Early seeding of Richter transformation in chronic lymphocytic leukemia [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3795.

Safety and efficacy of Ibrutinib in Indian patients with chronic lymphocytic leukemia.

e19585 Background: Ibrutinib, an oral Bruton's tyrosine kinase inhibitor, is approved for the treatment of chronic lymphocytic leukemia (CLL) in both upfront and relapsed/refractory. The prevalence of CLL is very low in India compared to western countries. Hence, the real-world data regarding efficacy and safety of Ibrutinib among the Indian population is very scarce. In this study, we aim to examine the toxicity profile, treatment response, and survival outcomes among Indian patients with CLL treated with Ibrutinib. Methods: In this retrospective study, we recruited all consecutive patients diagnosed with CLL, both treatment naïve (TN) and relapsed/refractory (R/R) CLL, on Ibrutinib (daily dose of 420 mg), registered at the Department of Medical Oncology, All India Institute of Medical Sciences, New Delhi, India between April 2016 and December 2021. Diagnosis of CLL, an indication of treatment, and response assessment were based on the recent guidelines (2018) from the International Workshop on CLL (iwCLL). Results: A total of 90 patients were recruited in this study, of which 33 were newly diagnosed and 57 had R/R CLL. Median age of the cohort was 60 years (range, 35–80 years) and male to female ratio was 3:1. The median total leukocyte count was 55x109/L and Del 17p was detected in 18% of cases. The R/R cases had received a median of 1(1-3) prior line of therapy. Overall response rate was observed in 76(84.4%), complete response was in 18 (20%) cases, partial response (PR) was in 49 (54.4%) cases, and in 9 (10%) cases PR with lymphocytosis (PR-L) was observed. With a median follow-up period of 15 months (4-60), 2-year progression-free survival (PFS) was 80% for the whole cohort. The median PFS was not reached in TN cases and was 18 months in R/R cases. Grade-3/4 adverse events (A/E) were seen in 17 (29.8%, n = 57) of R/R cases and in 3 (9.1%,n = 33) of TN cases. The most common Grade-3/4 A/E were infections in 19 (21.1%), (Varicella: 7, Pneumocystis: 6, Aspergilosis: 2, Mucormycosis: 1, Disseminated tuberculosis: 1, Encephalitis: 1, Others: 1) and cytopenias in 9 (10%) of cases. Other A/E were fatigue in 6 cases, arthralgia in 3, bleeding in 2, cutaneous rash in 2, reactivation of hepatitis-B in 2, diarrhea in 2, arrhythmia in 2, and autoimmune hemolytic anemia in one case. Ten patients (11.1%) had a dose reduction due to AE. The discontinuation rate was 27 (30%), due to progressive disease in 18 patients and due to adverse events in 9 patients. Twenty patients died, 14 due to disease progression or Richter's transformation, 5 due to infections, and 2 due to other reasons. Conclusions: This is the largest study of ibrutinib from India. Ibrutinib is safe and effective in upfront and R/R cases of CLL. Infections are the most common adverse event in R/R cases. Acyclovir and Co-trimoxazole prophylaxis can be considered in R/R cases of CLL in routine clinical practice . Arrhythmias were rare A/E as compared with the available literature.

A first-in-human phase 1 trial of nx-1607, a first-in-class oral CBL-B inhibitor, in patients with advanced solid tumor malignancies.

TPS2691 Background: Casitas B-lineage lymphoma proto-oncogene B (CBL-B) is an E3 ubiquitin ligase expressed in multiple immune cell lineages, which in contrast to cell surface immune checkpoints, acts as a regulator of both T and NK cell activation. Inhibition of CBL-B enhances T-cell response, increases response to suboptimal priming, and restores response in exhausted T cells. Thus CBL-B is a promising immune-oncology target and may overcome challenges seen with other T-cell directed therapies. NX-1607 is an oral small molecule inhibitor of CBL-B that has demonstrated anti-tumor activity and long-term survival in murine models as both a single agent and in combination with programmed cell death protein-1 (PD-1) antibodies. Further, NX-1607 elicits dose-dependent increases in cytokine secretion and proliferation in T-cell receptor-stimulated primary human T cells with enhanced tumor antigen-specific T-cell and NK cell anti-tumor responses. Thus, NX-1607 may be effective as a single agent or it may significantly enhance efficacy of other anti-tumor agents. Methods: NX-1607-101 is a first-in-human, multicenter, open-label, Phase 1 dose escalation and expansion trial evaluating NX-1607 in a variety of indications including platinum-resistant epithelial ovarian cancer (EOC), gastric cancer, squamous cell carcinoma of the head and neck (HNSCC), metastatic melanoma, non-small cell lung cancer (NSCLC), metastatic castration-resistant prostate cancer (mCRPC), malignant pleural mesothelioma (MPM), triple-negative breast cancer (TNBC), locally advanced or metastatic urothelial cancer, cervical cancer, microsatellite stable colorectal cancer (MSS CRC), and diffuse large B-cell lymphoma with Richter transformation (DLBCL-RT). The main objective is to establish the safety and tolerability of NX-1607, characterize PK/PD, and determine the recommended Phase 1b dose. NX-1607 will be given orally once daily at doses ranging from 5 to 100 mg in up to 6 dose levels. Dose escalation will proceed using an accelerated modified Fibonacci dose escalation design that transitions to a standard 3 + 3 design based on protocol-specific criteria. Up to 8 expansion cohorts in Phase 1b will be composed of patients with subsets of advanced cancers. Key eligibility criteria include patients with metastatic or unresectable disease that have progressed after prior therapy and for whom standard therapy with proven clinical benefit does not exist, is no longer effective, or is not appropriate. Prior treatment with immune checkpoint inhibitors or CAR-T cells with washout is allowed, but a history of active autoimmune disease is not. Up to 336 patients (60 in Phase 1a, 276 in Phase 1b using a Simon 2-stage design) will be enrolled at approximately 20 sites in the UK and US and treated until disease progression or unacceptable toxicity. Dose escalation is ongoing. Clinical trial information: NCT05107674.

A first-in-human phase 1 study of oral LOXO-338, a selective BCL2 inhibitor, in patients with advanced hematologic malignancies (trial in progress).

TPS7582 Background: B-cell lymphoma 2 (BCL2) is a key regulator of apoptosis and provides protection from cell death in many hematologic malignancies. LOXO-338 is an orally bioavailable small molecule inhibitor of BCL2, developed to achieve selectivity over BCL-xL and thus avoid dose-limiting thrombocytopenia associated with BCL-xL inhibition. In preclinical studies, LOXO-338 showed a favorable pharmacological profile, selectively inhibited BCL2, and was well-tolerated in vivo. LOXO-338 also demonstrated dose-dependent tumor growth inhibition in various murine xenograft models and showed improved efficacy in combination with pirtobrutinib, a highly selective, non-covalent (reversible) BTK inhibitor (Brandhuber et al. Cancer Res 2021 81 (13 Suppl) 1258). Methods: LOXO-BCL-20001 is a global open-label, first-in-human phase 1 study of oral LOXO-338 in patients (pts) with advanced hematologic malignancies who have received prior therapy. The study will be conducted in 2 parts. Part 1 will evaluate LOXO-338 as monotherapy and will explore different dosing strategies. Part 2 will evaluate LOXO-338 in combination with pirtobrutinib. Part 1 dose escalation will follow an i3+3 design. Each cycle will be 28 days. Eligible pts include those with CLL/SLL, mantle cell lymphoma, and Waldenström macroglobulinemia (WM) who received standard therapy. Pts with other B-cell non-Hodgkin lymphomas (NHL) who received standard therapy, are not candidates for available therapy, or have no options with proven benefit are also eligible. Pts with active or suspected Richter transformation, transformed low grade lymphoma, Burkitt or Burkitt-like lymphoma, and multiple myeloma are also eligible. Pts with AL amyloidosis are eligible in monotherapy dose expansion; all other pts are eligible in both monotherapy and combination dose expansion. Pts must not have progressed while receiving prior BCL2 inhibitor; those with WM or AL amyloidosis must not have received a prior BCL2 inhibitor. Key exclusion criteria include history of CNS involvement, stem cell transplant or CAR-T therapy &lt;60 days, concurrent anticancer therapy, and clinically significant cardiovascular disease. Primary objective is to determine the recommended phase 2 dose of oral LOXO-338 in pts who were previously treated for CLL/SLL and other B-cell NHL, administered alone or in combination with pirtobrutinib. Determining anti-tumor activity in pts with WM and AL amyloidosis is an additional primary objective of part 1 monotherapy. Secondary objectives include determining the safety profile, PK, and preliminary efficacy of LOXO-338 administered alone and in combination with pirtobrutinib. Antitumor activity will be evaluated based on overall response rate (ORR), progression-free survival (PFS), time to progression (TTP) and duration of response (DOR) according to disease-specific response criteria. Clinical trial information: NCT05024045.

Outcomes of Hodgkin variant Richter transformation in chronic lymphocytic leukaemia and small lymphocytic lymphoma in British Columbia.

Hodgkin variant Richter transformation (HvRT) is a rare and challenging complication of chronic lymphocytic leukaemia (CLL) for which information on prognostic factors and treatment approaches remain limited. We analysed characteristics and survival outcomes of a population-based cohort of 32 patients with HvRT identified in British Columbia over a 40-year period. Median interval from CLL diagnosis to HvRT was 5.6 years (range, 0-33.6), with five cases diagnosed concurrently. Most patients (80%) had treatment for CLL prior to HvRT. Median age at HvRT was 71 years (range, 51-86) and the majority of patients had high-risk disease, including stage 3-4 in 87% and International Prognostic Score (IPS) ≥ 4 in 65%. Two-year progression-free (PFS) and overall survival (OS) from HvRT were 47% (95% CI: 29%-64%) and 57% (95% CI: 38%-72%), respectively. OS from HvRT was significantly worse in those with anaemia (p= 0.02), elevated lactate dehydrogenase (p= 0.04), high IPS (p= 0.04), and worse performance status (p= 0.001). For those treated with curative-intent ABVD/ABVD-like therapy, 2-year PFS and OS were 70% (95% CI: 45%-85%) and 74% (95% CI: 49%-89%), respectively. In this real-world population-based cohort, HvRT was associated with poor clinical outcomes overall; however, those able to tolerate curative-intent therapy had similar survival to older patients with de novo HL.

Chronic Lymphocytic Leukemia Progression Diagnosis with Intrinsic Cellular Patterns via Unsupervised Clustering.

Simple SummaryDistinguishing between chronic lymphocytic leukemia (CLL), accelerated CLL (aCLL), and full-blown transformation to diffuse large B-cell lymphoma (Richter transformation; RT) has significant clinical implications. Identifying cellular phenotypes via unsupervised clustering provides the most robust analytic performance in analyzing digitized pathology slides. This study serves as a proof of concept that using an unsupervised machine learning scheme can enhance diagnostic accuracy. Identifying the progression of chronic lymphocytic leukemia (CLL) to accelerated CLL (aCLL) or transformation to diffuse large B-cell lymphoma (Richter transformation; RT) has significant clinical implications as it prompts a major change in patient management. However, the differentiation between these disease phases may be challenging in routine practice. Unsupervised learning has gained increased attention because of its substantial potential in data intrinsic pattern discovery. Here, we demonstrate that cellular feature engineering, identifying cellular phenotypes via unsupervised clustering, provides the most robust analytic performance in analyzing digitized pathology slides (accuracy = 0.925, AUC = 0.978) when compared to alternative approaches, such as mixed features, supervised features, unsupervised/mixed/supervised feature fusion and selection, as well as patch-based convolutional neural network (CNN) feature extraction. We further validate the reproducibility and robustness of unsupervised feature extraction via stability and repeated splitting analysis, supporting its utility as a diagnostic aid in identifying CLL patients with histologic evidence of disease progression. The outcome of this study serves as proof of principle using an unsupervised machine learning scheme to enhance the diagnostic accuracy of the heterogeneous histology patterns that pathologists might not easily see.

Richter's Transformation.

Richter's transformation (RT) occurs when chronic (CLL) transforms into an aggressive lymphoma. Despite improvements in the treatment of CLL, prognosis for RT remains poor. Here, we review current literature of RT, with a focus on novel treatment options. Efforts are underway to improve outcomes for patients with RT. While small molecule inhibitors have limited efficacy as monotherapy, recent developments combining them with chemo-immunotherapy show promise. Studies exploring the use of cellular therapies including chimeric antigen receptor T-cells and bispecific antibodies are ongoing. The current treatment paradigm for RT is to enroll these patients on a clinical trial when available, together with consultation for a consolidative allogeneic stem cell transplant. Trials investigating novel combinations and cellular therapy are ongoing. Determining predictive variables of transformation is imperative to design studies that allow for early identification and intervention for patients with RT.

The use of 18F-Choline-PET/CT in chronic lymphocytic leukaemia

The use of 18F-2-Fluoro-2-Desoxy-D-Glucose Positron Emission Tomography/Computed Tomography (FDG-PET/CT) has become an integral part of patient management in many lymphoid malignancies. However, the diagnostic accuracy of FDG-PET/CT in some indolent lymphoid malignancies with commonly low FDG-avidity, including Chronic Lymphocytic Leukaemia (CLL) can still be challenging in clinical routine [1-3,6,9]. CLL is defined as a low-grade proliferative B-cell proliferative disease often indolent, which can in about 5% of the cases turn into a more aggressive malignancy, most commonly into Diffuse Large B-Cell Lymphoma (DLBCL). This transformation is called Richter transformation, often detected too late and associated with a poor prognosis. Therefore, accurate imaging of CLL at an early stage could be useful for the management of the disease and improve patient’ssurvival [4,5,7,8,10].

Biology and Treatment of Richter Transformation.

Richter transformation (RT), defined as the development of an aggressive lymphoma on a background of chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL), represents a clinical unmet need because of its dismal prognosis. An increasing body of knowledge in the field of RT is arising from the recent development of preclinical models depicting the biology underlying this aggressive disease. Consistently, new therapeutic strategies based on a genetic rationale are exploring actionable pathogenic pathways to improve the outcome of patients in this setting. In this review, we summarize the current understandings on RT biology and the available treatment options.

Guideline for the treatment of chronic lymphocytic leukaemia

Guideline for the treatment of chronic lymphocytic leukaemia

Unusual Illustration of Richter Transformation in Chronic Lymphocytic Leukemia on FDG PET/CT.

A man with history of chronic lymphocytic leukemia (CLL) in remission had multiple rapidly growing lumps in recent 2 months. FDG PET/CT demonstrated disseminated FDG-avid nodal and extranodal lesions including those in unusual locations such as the nasopharynx, salivary glands, lungs, gastric wall, peritoneum, bones, and muscles. Subsequent biopsy of the right axillary mass showed absolute lymphocytosis with focus of large B-cell lymphoma. Flow cytometric immunophenotyping demonstrated κ-restricted CLL and B-cell lymphoma, consistent with Richter transformation of CLL. FDG PET/CT images of this case illustrated the most severe and most disseminated nodal and extranodal involvements of Richter transformation in CLL.

A Systematic Review on the Prevention and Control of Opportunistic Infections in Patients With Chronic Lymphocytic Leukemia Complicated by Richter's Transformation.

Chronic lymphocytic leukemia (CLL) is one of the most commonly occurring types of leukemia among the elderly population, contributing to an increased vulnerability to infections that are especially prolific in the immunosuppressed and the risk of rapid progression of the disease into a more aggressive manifestation of large cell lymphoma, a process called Richter’s Transformation (RT). CLL alone predisposes patients to develop infections; however, the additional complication of RT decreases survival and makes the prevention and control of infection for the CLL patient even more challenging. However, research that exists on preventing and controlling infection in CLL patients with RT is relatively limited. In most cases, studies have focused on the prevention of infection in CLL patients in general and with no reference to the progression of RT.Considering the dearth of research on infection prevention and control for patients with CLL complicated by RT specifically, the following review examines existing research in addressing the prevention and control of infection in CLL patients with RT and patients in general. The authors explored multiple databases such as PubMed, Google Scholar, and Science Direct. The ultimate focus of this study was to lay a fundamental understanding in preventing and controlling infection in CLL patients. After analyzing several studies, it can be concluded that identifying infections, even if rare, is a crucial aspect of managing CLL patients. A broad range of differential diagnoses should be sought in cases presenting with refractory CLL as well and management of infections before, during, or after CLL treatment should be considered.

La leucémie lymphoïde chronique

Chronic lymphocytic leukemia (CLL) is a low-grade B cell lymphoma with circulating cells, often revealed by hyperlymphocytosis. Its diagnosis and therapeutic indications (not systematic) have been defined in 2018. In fact, CLL can be separated in two entities differentiating themselves by their IGHV mutational status, but the search of other prognostic parameters like TP53 disruption is mandatory before treatment. Numerous genetic alterations and mutations exist in CLL. CLL cells are highly dependent from their b-cell receptor stimulation and from their microenvironment, which takes a central place in disease progression. Infections, dysimmune manifestations, cancers and Richter transformation are classic complications, and patients have poor vaccine response even without a treatment. Chemoimmunotherapy is being challenged by the new highly active drugs such as Bruton tyrosine-kinase inhibitors (ibrutinib, acalabrutinib) and by the association of venetoclax and anti-CD20. Future treatment strategies might integrate both new drugs and classical chemoimmunotherapy.

Results of ARI-0001 CART19 Cells in Patients With Chronic Lymphocytic Leukemia and Richter's Transformation.

CART19 cells are emerging as an alternative therapy for patients with chronic lymphocytic leukemia (CLL). Here we report the outcome of nine consecutive patients with CLL treated with ARI-0001 CART19 cells, six of them with Richter’s transformation (RT). One patient with RT never received therapy. The cytokine release syndrome rate was 87.5% (12.5% grade ≥3). Neurotoxicity was not observed in any patient. All patients experienced absolute B-cell aplasia, and seven (87.5%) responded to therapy. With a median follow-up of 5.6 months, two patients with RT experienced a CD19-negative relapse. In conclusion, ARI-0001 cell therapy was feasible, safe, and effective in patients with high-risk CLL or RT.