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Abstract Introduction Limited data currently exist on the role and efficacy of additional series of collagenase clostridium histolyticum (CCH) injections among Peyronie’s disease (PD) men who have previously failed a first series of injections. We sought to evaluate outcomes of a novel protocol for CCH injections among men who had previously failed 6-8 CCH injections using a traditional approach. Objective To evaluate whether additional rounds of CCH using a novel protocol in men previously unresponsive results in greater curve improvements. Methods A randomized, controlled trial (NCT05108558) is ongoing. All participants previously failed to achieve ≥20% curvature improvement with 6-8 prior CCH injections. Men were randomized 3:1 to receive either CCH + traction (RestoreX) + sildenafil (treatment) up front or initial observation followed by treatment (controls). Outcomes were compared between treatment and control groups. Key measures included objective curve improvements and standardized/non-standardized questionnaires, with assessments obtained at baseline, 6-weeks after completion of CCH (treatment arm), after the no treatment period (controls), and at 1 year. Results A total of 38/40 men have been randomized to date, with 22 having fully completed treatment. Mean age was 57 years, with a median PD duration of 22 months. Median composite baseline curvature was 65 degrees, with 40% having hourglass or indentation deformities, 8% calcification, median baseline IIEF-EFD 20, and 58% able to have penetrative intercourse. Median estimated improvement with the prior CCH series was 0% (IQR 0, 18.8), and the median number of prior injections was 8. The majority of men were dissatisfied with their prior series of CCH (58% vs 35% satisfied, 8% neutral). Of the 22 men who had completed the study protocol, 50% required 1 series, 14% 2 series, 29% 3 series, and 7% 4 series. Compared to the no treatment arm, treated men experienced significantly greater improvements (median 60 degrees vs 0, p = 0.01). IIEF-EFD was non-statistically higher in treated men (0 vs -5, p = 0.17). 92% of men reported a subjective major improvement in curvature, with the median subjectively estimated improvement 90%. 42% reported improved sensitivity (58% no change), while 63% reported improved or no change in erectile function, with 9% unsure, and 27% worse. Post-treatment, 92% of men were very satisfied with CCH as a treatment and 8% neutral. Conclusions Repeating CCH using a novel protocol after an initially unsuccessful course of CCH achieves significant improvements in curvature and patient satisfaction. Additional data, including external validation, are warranted. Disclosure Yes, this is sponsored by industry/sponsor: Endo Pharmaceuticals. Clarification: Industry funding only - investigator initiated and executed study. Any of the authors act as a consultant, employee or shareholder of an industry for: PathRight Medical.

Introduction Patients (pts) with progressive disease after ≥2 prior lines of systemic therapy are unlikely to derive additional benefit from current salvage immunochemotherapies, and survival declines significantly with each subsequent treatment. Pts with refractory disease following second-line therapy have worse outcomes, with reported overall response rates (ORRs) of 1% to 14% and overall survival (OS) of 5 months (Blood. 2017;130[16]:1800-1808). While chimeric antigen receptor (CAR) T-cell therapy has become a preferred strategy in the second- and third-line settings, pts with R/R disease following CAR-T experience dismal survival, with progression-free survival (PFS) and OS as low as 3 and 5 months, respectively, and no agreed standard of care post CAR-T (Blood. 2022;140[24]:2527-2529). The randomized, global, phase 3 ECHELON-3 study (NCT04404283) was conducted in pts with R/R DLBCL after ≥2 prior therapies who were ineligible for hematopoietic stem cell transplant and/or CAR-T. Here, we present subgroup analyses in pts with 2 prior lines of therapy, refractory disease, or prior CAR-T. Methods In these subgroup analyses of ECHELON-3, eligible pts had 2 prior lines of systemic therapy, disease refractory to the last prior therapy, or prior exposure to CAR-T. Pts could qualify for ≥1 subgroup and were analyzed separately. Refractory disease was defined as stable or progressive disease as best overall response to last line of treatment or relapse ≤6 months from the end of treatment. Pts were randomized 1:1 to receive brentuximab vedotin (BV; 1.2 mg/kg) or placebo every 3 weeks (q3w), in combination with rituximab (R; 375 mg/m2) q3w and lenalidomide (Len; 20 mg) once daily. Efficacy was assessed by investigators per Lugano 2014 classification. The primary endpoint was OS, with key secondary endpoints of PFS and ORR. P values are descriptive. Results In total, 230 pts were enrolled in ECHELON-3 from April 2021 to November 2023, with a median follow-up of 16.4 months (range, 0.1-31.5 months). Overall, 94 pts with 2 prior lines of systemic therapy were enrolled and randomized to BV+Len+R (n=48) or placebo+Len+R (n=46). Median OS was 16.3 months (95% CI, 12.6 months-not estimable) with BV+Len+R vs 8.5 months (95% CI, 4.1-15.8 months) with placebo+Len+R (hazard ratio [HR], 0.557; 95% CI, 0.317-0.977; P=.0388). Median PFS was 7.1 months (95% CI, 3.6-12.6 months) with BV+Len+R vs 2.7 months (95% CI, 1.4-4.0 months) with placebo+Len+R (HR, 0.462; 95% CI, 0.279-0.764; P=.0020). ORR was 68.8% (95% CI, 53.7%-81.3%) with BV+Len+R vs 43.5% with placebo+Len+R (95% CI, 28.9%-58.9%; P=.0216); complete response (CR) rate was 52.1% vs 13.0%, respectively. Additional data for pts by lines of therapy received will be presented. In total, 194 pts with disease refractory to the most recent systemic therapy were enrolled and randomized to BV+Len+R (n=98) and placebo+Len+R (n=96). Median OS was 11.7 months (95% CI, 8.8-16.3 months) with BV+Len+R vs 5.5 months (95% CI, 3.7-8.5 months) with placebo+Len+R (HR, 0.566; 95% CI, 0.396-0.808; P=.0015). Median PFS was 4.1 months (95% CI, 2.8-5.4 months) with BV+Len+R vs 1.5 months (95% CI, 1.4-2.6 months) with placebo+Len+R (HR, 0.508; 95% CI, 0.363-0.712; P<.0001). ORR was 59.2% (95% CI, 48.8%-69.0%) with BV+Len+R vs 29.2% (95% CI, 20.3%-39.3%) with placebo+Len+R (P<.0001); CR rate was 34.7% vs 11.5%, respectively. Overall, 67 pts who received prior CAR-T were enrolled and randomized to BV+Len+R (n=32) and placebo+Len+R (n=35). Median OS was 15.6 months with BV+Len+R vs 4.4 months with placebo+Len+R (HR, 0.38; 95% CI, 0.2-0.75). Median PFS was 3.0 months with BV+Len+R vs 1.4 months with placebo+Len+R (HR, 0.41; 95% CI, 0.22-0.76). ORR was 65.6% (95% CI, 46.8%-81.4%) with BV+Len+R vs 25.7% (95% CI, 12.5%-43.3%) with placebo+Len+R (P=.0014); CR rate was 37.5% vs 11.4%, respectively. Conclusions BV+Len+R demonstrated a clinically meaningful improvement in all key efficacy outcomes, including CR and OS, in pts with 2 prior lines of therapy, disease refractory to prior treatment, or prior CAR-T. This treatment benefit was generally consistent with that observed in the overall ECHELON-3 study population. Therefore, BV+Len+R has the potential to address an unmet need for effective and tolerable therapy in heavily pretreated pts, as described above.

BACKGROUND ELRA is a humanized, BCMA/CD3 bispecific antibody. In the phase 2 registrational MagnetisMM-3 (MM-3) trial, SC ELRA given as 2 step-up priming doses (12 mg on day 1 and 32 mg on day 4 of cycle 1) followed by 76 mg QW in patients (pts) with RRMM naive to BCMA-directed therapy resulted in an ORR of 61.0%. With a median follow-up of 28.4 mos, the median DOR, PFS, and OS were not reached (NR; 2-year rate, 66.9%), 17.2, and 24.6 mos, respectively. Overall, 56.3% of pts had CRS (grade 2, 14.3%; no grade ≥3). Most events occurred after doses 1 (44.5%), 2 (20.2%), and 3 (5.9%); 0.8% (1 pt) had CRS with doses ≥4. Recurrent CRS occurred in 15.1% of pts. The phase 1/2 MagnetisMM-9 (MM-9; NCT05014412) study is examining an alternative priming regimen and longer dosing intervals of ELRA. Here, we present updated MM-9 results. METHODS In MM-9, pts with RRMM and disease refractory to ≥1 IMiD drug, ≥1 PI, and ≥1 anti-CD38 antibody were given SC ELRA as step-up priming doses of 4 and 20 mg on Day 1 and Day 4 of Cycle 1, respectively. After the priming doses, ELRA 76 mg was given QW for the next 6 cycles (Part 1) or for 1 cycle followed by 116 (dose level 1 [DL1]) or 152 (dose level 2 [DL2]) mg Q2W for the next 5 cycles (Part 2A). After 6 cycles, the dosing frequency was decreased from QW to Q2W (Part 1) or from Q2W to Q4W (Part 2) in pts who achieved ≥PR lasting ≥2 months. The recommended phase 2 dose from Part 2A (152 mg, DL2) was evaluated in Part 2B (dose expansion). The primary endpoint for both parts is grade ≥2 CRS rate per ASTCT criteria during Cycle 1. Secondary endpoints include evaluation of efficacy and adverse events. Data cutoff: February 13, 2024. RESULTS Overall, 85 pts (median age, 64.0 y) were treated with ELRA. The majority (72.9%) of pts had R-ISS stage I/II disease (23.5% with R-ISS stage III); 31.8% had high-risk cytogenetics. Median number of prior lines of therapy was 5.0 (range, 1-12). The median treatment duration was 8.6, 2.9, 1.4, and 3.3 mos, in Part 1, Part 2A DL1, Part 2A DL2, and Part 2B, respectively. Median follow-up for pts overall (n=85), in Part 1 (n=33), Part 2A DL1 (n=12), Part 2A DL2 (n=11), and Part 2B (n=29) was 10.4, 23.3, 16.5, 15.2, and 9.3 mos, respectively. Overall, the ORR was 58.8%. For pts in Part 1, Part 2A DL1, Part 2A DL2, or Part 2B, ORR was 66.7%, 58.3%, 36.4%, and 58.6%, respectively; median DOR was NR (9-mo rate: 86.4%), 10.8 mos (9-mo rate: 80.0%), NR (9-mo rate: 100.0%), and NR (9-mo rate: 84.8%); median PFS was 17.1 (9-mo rate: 62.8%), 11.6 (9-mo rate: 50.9%), 1.6 mos (9-mo rate: 40.0%), and NR (9-mo rate: 57.1%); median OS was NR (9-mo rate: 75.8%), 17.4 mos (9-mo rate: 66.7%), NR (9-mo rate: 60.0%), and NR (9-mo rate: 72.4%), respectively. For pts in Part 1, Part 2A DL1, Part 2A DL2, and Part 2B, grade ≥2 CRS rates during Cycle 1 were 15.2%, 16.7%, 27.3%, and 6.9%, respectively. For pts in Part 1, Part 2A DL1, Part 2A DL2, and Part 2B, CRS rates were 30.3%, 33.3%, 36.4%, and 24.1% after dose 1, 27.3%, 25.0%, 36.4%, and 24.1% after dose 2, 15.2%, 33.3%, 27.3%, and 20.7% after dose 3, 6.1%, 8.3%, 0%, and 3.4% after dose 4, and 6.1%, 16.7%, 9.1%, and 0% after doses ≥5. Recurrent CRS occurred in 18.2%, 33.3%, 18.2%, and 17.2% of pts in Part 1, Part 2A DL1, Part 2A DL2, and Part 2B. The most common (>60%) TEAEs (any grade/grade ≥3) were hematologic TEAEs (Part 1, 75.8%/75.8%; Part 2A DL1, 83.3%/83.3%; Part 2A DL2, 81.8%/81.8%; Part 2B, 79.3%/69.0%), infections (Part 1, 78.8%/48.5%; Part 2A DL1, 83.3%/66.7%; Part 2A DL2, 72.7%/63.6%; Part 2B, 62.1%/37.9%), and CRS (Part 1, 60.6%/0%; Part 2A DL1, 83.3%/0%; Part 2A DL2, 90.9%/9.1%; Part 2B, 48.3%/0%). Grade 5 TEAEs not including PD were infection (n=4), fall (n=1), subdural hematoma (n=1), and food poisoning (n=1). CONCLUSIONS The 4/20 mg step-up priming regimen and alternative dosing schedules in MM-9 resulted in similar efficacy vs the step-up regimen used in the registrational MM-3 study (12/32 mg). Responses were durable with encouraging PFS and OS with the alternative step up and longer dosing schedule. While the overall safety signals with the alternative step up regimen are similar to those seen with MM-3, the CRS profile differed with more CRS events after each subsequent dose and a higher prevalence of recurrent CRS. Thus, the optimal ELRA step-up regimen remains 12/32 mg from the original regimen in the MM-3 study. In addition, these early results suggest that reducing the dose frequency of ELRA may not compromise efficacy.

Introduction: Mantle cell lymphoma (MCL) is an uncommon B-cell non-Hodgkin lymphoma (NHL) Prognosis is highly variable due to underlying biological and molecular heterogeneity. The first-line (1L) treatment paradigm for MCL continues to evolve with increasing use of bruton tyrosine kinase inhibitors (BTKi) and decreasing use of autologous stem cell transplant (ASCT). TP53 alterations are associated with inferior outcomes in MCL. The aim of this retrospective study is to determine treatment strategies and clinical outcomes in MCL patients based on TP53 gene mutation status. Methods: Retrospective data were collected from 19 institutions in the United States from 1/1993 to 1/2024. We examined treatment patterns and outcomes among MCL patients >18 years of age with known TP53 mutation status by sequencing. Patients who did not receive treatment were excluded. The analysis was stratified based on presence of TP53 mutations. Systemic therapies were categorized as chemo-immunotherapy (CIT), non-chemotherapy (including monoclonal antibodies, lenalidomide, venetoclax, and novel agents on clinical trial), and regimens containing BTKi. The primary outcome was overall survival (OS) and secondary outcomes were progression free survival (PFS) and time to next treatment (TTNT). OS and PFS were estimated with the Kaplan-Meier method and log-rank tests were used to compare groups. Results: 645 patients were included in the study, with 468 men (72.6%) and median age was 64 years (range 30-89). 230/645 patients (35.7%) had a TP53 mutation, of which 182 (79%) were identified prior to 1L. While the male/female distribution was the same between the mutated and unmutated groups, median age at diagnosis and MIPI risk score was higher in the TP53 mutated group (age 65.9 vs 63.1 yrs, p= 0.015; MIPI 6.4 vs 6.1, p<0.001). TP53 unmutated patients had a median of 1 line of therapy vs. 2 for the mutated group (p<0.001, range 1-8). Blastoid histology and higher ki67 were also associated with the TP53 mutated group (p=0.045, 0.01 respectively) The median OS was 14.2 years for TP53 unmutated and 8.3 years for TP53 mutated patients (p<0.0001). PFS in 1L was 0.95 years in TP53 mutated compared to 2.02 years in TP53 unmutated group (p<0.0001). Selection of 1L therapeutic strategy was not associated with presence of TP53 mutation (Χ2 p= 0.21) although more patients in the TP53 unmutated group underwent ASCT (119/415 vs 38/230; Χ2 p=0.0006) TP53 mutation was associated with inferior survival compared to TP53 unmutated patients for CIT in 1L but the difference did not reach statistical significance when non-chemotherapy regimens and regimens containing BTKi were used. For CIT in 1L, 5 year OS was 78% [71-84%] for unmutated compared to 58% [48-67%] for the mutated group (p=0.0001 ). For non-chemotherapy regimens, 5 year OS for unmutated patients was 73% [52- 86%] compared to 52% [25-73%] for the mutated group (p=0.09). For regimens containing BTKi, 5 year OS for unmutated was 93% [81-97%] compared to 57% [28-78%] for mutated (p=0.07). Within the TP53 mutated group, there were no differences in any clinical outcomes between those receiving CIT, non-chemotherapy, or BTKi in 1L. While median OS appeared numerically longer in the BTKi group (14.4 yrs vs 8.8 yrs for CIT and 6.8 yrs for non-chemotherapy), the difference did not reach statistical significance (p=0.58). In contrast,TP53 unmutated patients who received CIT in 1L had better TTNT (p=0.0039) compared to those in non-chemotherapy and BTKi groups. There was no improvement in PFS (p=0.79) or OS (p=0.47). Conclusions To our knowledge this is the largest retrospective real world dataset of MCL treatment outcomes stratified by TP53 mutation. As in prior studies, TP53 mutation portends a worse prognosis in MCL compared to TP53 unmutated patients, but outcomes are better than historically reported. CIT in 1L was not associated with improved OS in either group. Irrespective of TP53 mutation status, incorporation of BTKi in first line was not associated with improved clinical outcomes. The gap in OS between TP53 mutated and unmutated MCL may be narrowing as treatment paradigms shift away from intensive induction chemotherapy and ASCT, and due to an increasing number of effective therapies for relapsed patients. Clinical trials of novel agents are needed to further improve the OS of TP53 mutated MCL patients.

Background Follicular lymphoma (FL) is a generally indolent disease where a watch and wait strategy is standard in asymptomatic patients (pts) with a low tumor-burden. Harnessing antitumor immunity through an anti-tumor immunization strategy at this stage may delay or avoid the subsequent need for more toxic and complex therapies. EO2463 is a therapeutic vaccine designed from non-self protein sequences, derived from gut bacteria, including 4 HLA-A2 synthetically produced 9-mer CD8 cytotoxic T cell epitopes, exhibiting molecular mimicry with specific epitopes on the B cell markers CD20, CD22, CD37, and CD268 (BAFF-receptor). Additionally, EO2463 contains a CD4 helper epitope UCP2 derived from hTERT. The compound expands pre-existing memory CD8 T cells recognizing the non-self protein sequences from gut bacteria which can then cross-react with the selected B cell antigens on tumor cells. EO2463 is being used to drive anti-tumor immunity against B cell malignancies, and has demonstrated long-lasting, specific CD8-memory T cell responses and clinical activity in relapsed/refractory FL and marginal zone lymphoma (MZL) [J Clinical Oncol 2024, 42 (S16), 7058]. Furthermore, CD8 T cells expanded from samples of patients treated with EO2463 can kill HLA-A2 expressing lymphoblastoid cell lines presenting the B cell targets [Hematological Oncol 2023, 41 (S2), 581-582]. Methods The current report describes Cohort 2 of trial EONHL1-20/SIDNEY (NCT04669171) and includes pts with newly diagnosed, previously untreated FL, grade 1-3A, HLA-A2, and not in need of treatment. Pts receive EO2463 (300μg/peptide) SC with adjuvant Montanide ISA 51 VG, q2 weeks (w) x 4, then q4w, for a total of 12 doses (39w; PET-CTs at w6, w19, and w42). Planned accrual for this cohort is 25 pts. Immune responses were assayed on thawed pt peripheral blood mononuclear cells by flow cytometry and EO2463 peptide specific tetramers or by IFN-γ ELISPOT (assaying responses against 9-mer peptides from CD20, CD22, CD37, and CD268; and from peptides of EO2463) without any proceeding in vitro stimulation (ex vivo). Results As of June 2024, 15 pts had started study treatment. Median age was 62 (range 55-66) year, 7 male and 6 female, 2 pts Ann Arbor stage I/II, 5 stage III, and 8 stage IV. Ten of 15 pts were still on treatment; median treatment duration was 18.4 weeks (range 5-39 w) for all pts. Among 13 evaluable pts, best responses by PET-CT using Lugano criteria were 1 pt CR, 5 pts PR (46% objective responses (OR)), 3 pts SD, and 4 pts PD. Of those with PD per Lugano, 2 had isolated increases in FDG-uptake without increase in lesion size/number at w6 and both remain on treatment (per protocol based on LYRIC criteria). OR was first noted w6 in 3 pts and w19 in 3 pts; duration of response is not evaluable at this time due to short follow-up. The pt with CR had isolated increases in FDG-uptake at w6, PR at w19, and CR at w35. Anti-EO2463 immune responses were observed in 4 of 5 tested pts at the 1st testing timepoint (w5) and onwards (currently longest tested up until w31). In an exploratory analysis, the percentage of EO2463 peptide specific CD8 T cells measured by tetramers seemed linked to clinical response (OR 3 pts vs non-OR 2 pts; 2-sided T-test, p=0.02; range of percentages in pts with OR 0.85%-1.39% of all CD8 T cells in peripheral blood, range in pts with non-OR 0.17%-0.27%). Functionality and cross-reactivity of responses were shown by IFN-γ ELISPOT using 9-mer peptides corresponding to the B cell targets in 4 tested pts. Expanded antigen-specific CD8 T cells displayed a memory phenotype; effector/memory (TEM), and terminally differentiated effector memory CD8 T cells (TEMRA). The most common related AEs were grade 1 (7 pts) and grade 2 (5 pts) local administration site reactions (mainly erythema, pruritus, and induration). Other related AEs in > 1 pt were grade 1 headache (2 pts) and grade 1-3 fatigue/asthenia (3 pts). Asthenia lasting 2 days was the only related grade 3 adverse event (AE). Conclusions EO2463 monotherapy is associated with a very manageable safety profile and appears to demonstrate meaningful single-agent efficacy in FL. Consistent with the preclinical hypothesis, expansion of specific CD8 memory T cells may be associated with response. Results will be expanded at the meeting. Study EONHL1-20/SIDNEY also includes cohorts, not covered in this abstract, exploring EO2463 plus rituximab for 1st line FL/MZL, and EO2463 plus lenalidomide/rituximab in relapsed FL/MZL.

Background Follicular and marginal zone B cell lymphoma (FL; MZL) demonstrate an indolent course with heterogeneous outcomes and a potential for spontaneous remissions indicating immune system intervention. T cell-based therapeutic approaches are therefore an attractive proposition in FL and MZL. EO2463 peptide immunotherapy expands pre-existing memory CD8 T cells recognizing non-self-protein sequences from gut bacteria which cross-react with B cell antigens. The compound includes 4 HLA-A2 synthetically produced epitopes which exhibit molecular mimicry with the B cell markers CD20, CD22, CD37, and CD268 (BAFF-receptor), as well as a the CD4 helper-epitope UCP2 derived from hTERT. EO2463 is being used to drive anti-tumor immunity against B cell malignancies, and has demonstrated long-lasting, specific CD8-memory T cell responses and clinical activity in relapsed/refractory FL and MZL [J Clinical Oncol 2024, 42 (S16), 7058]. Furthermore, CD8 T cells expanded from samples of patients (pts) treated with EO2463 can kill HLA-A2 expressing lymphoblastoid cell lines presenting the B cell targets [Hematological Oncol 2023, 41 (S2), 581-582]. Methods The current report describes testing of a possible biomarker in the phase 1 portion of the ongoing EONHL1-20/SIDNEY trial (NCT04669171).This part of the trial (“Cohort 1”) included pts (n=9) with relapsed (at least 1, no limit, prior treatments) FL and MZL, stage 1-3A, confirmed to be positive for HLA-A2. Pts received EO2463 (150 [n=3] or 300μg/peptide [n=6]) SC with adjuvant Montanide ISA 51 VG q2 weeks (w) x 4, then q4w, for a max of 12 months; at w7 lenalidomide (20 mg/day for 21/28 days up to 12 cycles) was added (EL), and if no complete remission (CR) at w19, rituximab (375 mg/m IV, q1w x 4, then q4w x 4) was also added (ER2). Immune responses and clinical outcomes of Cohort 1 were previously reported [J Clinical Oncol 2024, 42 (S16), 7058]. To assess a possible biomarker, tetramers were used to specifically detect CD8 T cells recognizing the 4 epitopes in the EO2463 compound (derived from gut bacterial proteins exhibiting molecular mimicry with the B cell markers CD20, CD22, CD37, and CD268). The tetramers were all marked with phycoerythrin. Thawed samples of peripheral blood mononuclear cells taken at start of w5 (after 2 administrations of EO2463 monotherapy, each followed by 2w observation) were stained ex vivo (without any in vitro stimulation) with the tetramers and assayed by flow cytometry. Results are presented as percentage of EO2463 specific CD8 T cells among all CD8 T cells in the peripheral blood of the pt. Results Among the 9 treated pts, PET-CT at w6 (after 3 administrations of EO2463 monotherapy) suggested possible clinical activity in 4/9 pts (1 PR, 1 pt size reduction 15%, 1 pt 20% reduced tracer uptake, 1 pt 5/6 target lesions reduced metabolic activity). By PET-CT at w42 (after 12 administrations of EO2463 monotherapy, 11 cycles of lenalidomide, and rituximab treatment) the Lugano response assessment was complete response in 6/9 pts. A positive biomarker response was assessed in 5/9 pts (percentage of specific CD8 T cells ranged from 0.2-2.1%). EO2463 monotherapy PET-CT activity at w6 (n=4/9 pts): 4 of 4 pts with clinical activity were biomarker positive and 1/5 of the other pts was also positive; this pt had an isolated increase in FDG-uptake at w6, followed by a CR at w19. Four further other pts were biomarker negative. In this limited sample, the biomarker had sensitivity 100% and specificity 80%. EO2463 in combination with lenalidomide/rituximab PET-CT CR at w42 (n=6/9): 5 of 6 pts with CR were biomarker positive and 1 pt with CR was negative; the pt with a negative test had no objective tumor response until after rituximab. In this limited sample, the biomarker showed sensitivity 83% and specificity 100%. Conclusions The current preliminary assessment indicates that direct ex vivo tetramer staining for specific CD8 T cells after short term (5 w) treatment with EO2463 monotherapy could be a possible biomarker for clinical response, both for EO2463 monotherapy response, and for response to EO2463 in combination with lenalidomide/rituximab. We plan to validate these findings in the ongoing study cohorts of the trial; expansion phase 2 cohorts, exploring EO2463 monotherapy in the “watch & wait” setting, EO2463 plus rituximab for 1st line FL/MZL, and EO2463/lenalidomide +/- rituximab in relapsed FL/MZL.

Introduction: High-risk smoldering multiple myeloma (SMM) is an asymptomatic precursor disorder to active multiple myeloma (MM) without approved treatment options. However, recent evidence suggests patients at high risk of progression to MM may benefit from early treatment. Daratumumab (DARA) is a human IgGκ monoclonal antibody targeting CD38 with direct on-tumor and immunomodulatory mechanisms of action. DARA is approved as monotherapy for relapsed/refractory MM (RRMM) and in combination with standard-of-care regimens for RRMM and newly diagnosed MM. Based on the encouraging activity and tolerability observed with DARA monotherapy in patients with intermediate- or high-risk SMM in the phase 2 CENTAURUS study, the phase 3 AQUILA study sought to determine if DARA could delay progression to MM versus active monitoring. Here we report the primary analysis from the AQUILA study. Methods: Eligible patients had a confirmed diagnosis of high-risk SMM for ≤5 years, defined as clonal bone marrow plasma cells (BMPCs) ≥10% and ≥1 risk factor (serum M protein ≥30 g/L, IgA SMM, immunoparesis with reduction of 2 uninvolved Ig isotypes, serum involved:uninvolved free light chain ratio ≥8 and <100, and/or clonal BMPCs >50% to <60%). Focal and lytic lesion assessment was performed in screening by CT and MRI and centrally reviewed prior to study enrollment. Patients were randomized 1:1 to receive DARA SC versus active monitoring. DARA (QW in Cycles 1 and 2, Q2W in Cycles 3-6, and Q4W thereafter) was given in 28-day cycles until cycle 39, 36 months, or disease progression, whichever came first. The primary endpoint was progression-free survival (PFS), defined as progression to active MM as assessed by an independent review committee and according to IMWG diagnostic criteria for MM (SLiM-CRAB) or death. Major secondary endpoints included overall response rate (ORR), PFS on first-line MM treatment (PFS2), and overall survival (OS). Results: A total of 390 patients (DARA, n = 194; active monitoring, n = 196) were randomized. Median (range) age (64 [31-86] years) and time from initial SMM diagnosis to randomization (0.72 [0-5.0] years) were balanced between treatment groups. Median treatment duration in the DARA group was 38 cycles (35.0 months). At a median (range) follow-up of 65.2 (0-76.6) months, PFS was significantly improved with DARA versus active monitoring (HR, 0.49; 95% CI, 0.36-0.67; P <0.0001). Median PFS was not reached in the DARA group versus 41.5 months for active monitoring; estimated 60-month PFS rates were 63.1% versus 40.8%, respectively. Prespecified analyses showed generally consistent PFS improvement with DARA versus active monitoring across subgroups. ORR was 63.4% with DARA versus 2.0% with active monitoring (P <0.0001). As of the clinical cutoff, 64 (33.0%) patients in the DARA group and 102 (52.0%) patients in the active monitoring group had started first-line MM treatment. Median time from randomization to the date of first-line MM treatment was not reached with DARA versus 50.2 months with active monitoring (HR, 0.46; 95% CI, 0.33-0.62; nominal P <0.0001). There was a positive trend in favor of DARA for PFS2 (HR, 0.58; 95% CI, 0.35-0.96) and OS (60-month OS rates: DARA, 93.0%; active monitoring, 86.9%; HR, 0.52; 95% CI, 0.27-0.98). A total of 41 deaths were observed, 15 for the DARA group and 26 for the active monitoring group. Grade 3/4 treatment-emergent adverse events (TEAEs) occurred in 40.4% and 30.1% of patients in the DARA and active monitoring groups, respectively. The most common (≥5% in either group) grade 3/4 TEAE was hypertension (DARA, 5.7%; active monitoring, 4.6%). The frequency of TEAEs leading to DARA discontinuation was low (5.7%), as was the incidence of fatal TEAEs in both groups (DARA, 1.0%; active monitoring, 2.0%). Conclusions: DARA monotherapy was well tolerated and demonstrated a clinically meaningful and significant benefit in preventing or delaying progression to active MM compared with active monitoring in patients with high-risk SMM. ORR was significantly higher and time to first-line MM treatment was prolonged with DARA compared with active monitoring. This was accompanied by positive trends for PFS2 and OS in favor of DARA. These results strongly support the benefit of early intervention with DARA monotherapy versus active monitoring, the current standard of care, in patients with high-risk SMM.

Background: Anti-BCMA CAR T cells are a new standard of care for the treatment of RRMM patients. Hence, it is paramount to identify determinants of response and resistance for individualized approaches. There is emerging data about the importance of depth of response in prolonged progression-free survival (PFS) and of genetic antigen escape in treatment resistance. By contrast, there is limited understanding of how patient' outcomes are shaped by immune fitness prior aphaeresis, and virtually no data about CAR T and endogenous profiles post infusion. Aim: Characterize immune dynamics and investigate its prognostic value in RRMM patients treated with CAR T cells. Methods: Immune profiling was performed using multidimensional and computational flow cytometry in 285 bone marrow aspirates from 120 RRMM patients enrolled in the KarMMa phase 2 trial. In total, 170 immune clusters were identified and systematically quantified in a pileup analysis of samples collected before and at months 1, 3, 6 and 12 after CAR T infusion. Immune scores were developed using cox regression with 10-fold cross-validation. Results: At baseline (n = 63), there were significant associations between the bone marrow immune composition and the number of prior lines of treatment, prior autologous transplant and staging. Namely, there were higher proportions of ICOS, PD1, TIGIT and TIM3 positive cells within the CD4+ and CD8+ T cell compartments from heavily pretreated patients and those with R-ISS 3. A baseline immune score defined by the percentages of GrzmB+HLADR+ cytotoxic NK cells, TIGIT+ Tregs, CD4+CD127+ICOS+ and CD4+CD25+CD127+TIGIT+, CD8+TIGIT+, CD8+GrzmB+HLADR+ and CD8+CD27+CD95+CD45RAloCD197lo T cells was associated with PFS. Patients with low vs high risk immune score at baseline had median PFS of 25 vs 6 months, respectively (p < .001). Interestingly, there were no significant associations between the baseline risk score and treatment or staging, suggesting potential complementarity of immune profiling with other prognostic factors. At month 1 after infusion (n = 55), the presence of >1% vs <1% CAR T cells was associated with longer PFS (medians of 20 vs 8 months, p = .002). In addition to the magnitude of CAR T persistence, it was interesting to observe increased percentages of CD8+ CAR T cells in patients with <5 prior lines of therapy, of CD4+HLADR+ and CD8+TEMRA CAR T cells in patients with R-ISS 1/2, as well as of PD1+TIM3+ CD4+ and CD8+ CAR T cells in patients with R-ISS 3. Moreover, the phenotype of CAR T cells was associated with PFS. Patients with low vs high risk immune score (ie, based on the percentages of CD4+CD57+, CD8+CD27-EM, CD8+PD1+TIM3+ and CD4+CD8+ CAR T cells) had median PFS not reached vs 11 months, respectively (p < .0001). Similarly to the above, there were no significant associations between the CAR T immune risk score and treatment or staging, suggesting potential complementarity of CAR T quantification and phenotyping post-infusion with other patient' characteristics. Next, we investigated endogenous T cell dynamics in 51 RRMM patients with paired samples prior and after CAR T infusion. There were significant differences in the frequencies of 30 immune clusters, including CD27+ naïve and EM CD4+ and CD8+ T cells, ICOS+ and TIGIT+ Tregs, CD4+ and CD8+ T cells, as well as of CD25+CD127+ CD4+ and CD8+ T cells. Furthermore, an immune risk score defined at the latest available time point (n = 95) was associated with PFS (p < .0001). Patients with lower levels of GrzmB+ cytotoxic NK cells and of immunoregulatory HLADR- NK cells, as well as of CD4+CD27+CD95+CM, CD4+HLADR+, CD8+PD1+ and CD8+CD27-CD95+EM T cells showed a high risk score and a median PFS of 6 vs 20 months in patients with low risk immune score. Conclusions: This is one of the largest dynamic studies of immune profiling in a clinical trial investigating anti-BCMA CAR T cells in RRMM. Our results uncovered that patient' immune status is shaped by prior treatment and staging, and that the distribution of different NK, Treg, CD4+ and CD8+ T cells prior aphaeresis is associated with PFS. Furthermore, the phenotype of CAR T cells at month 1 after infusion may be as prognostic as its percentage. We also showed how treatment with CAR T cells modulates the bone marrow immune composition and how it may contribute to immune escape vs surveillance. Altogether, this study supports immune profiling for improved understanding of response and resistance to CAR T cells in RRMM.

Background:Patients (pts) with multiple myeloma (MM) often receive immunomodulatory drugs (IMiDs; eg, lenalidomide), proteasome inhibitors (eg, bortezomib), and anti-CD38 monoclonal antibodies (mAbs) as part of their initial treatment. However, most pts relapse following initial treatment, with increasing attrition rates observed at each subsequent line of therapy (LOT), creating an unmet need for treatment options for pts with relapsed/refractory MM (RRMM) who have prior exposure to these agents. Current regimens for pts who have prior exposure to lenalidomide and anti-CD38 mAbs include elotuzumab, pomalidomide, and dexamethasone (EPd; approved in Europe and the US) and pomalidomide, bortezomib, and dexamethasone (PVd; approved in Europe and Australia), but disease control, as well as depth and durability of response, could be improved. Talquetamab (tal) and teclistamab (tec), targeting CD3 and either G protein-coupled receptor family C group 5 member D (GPRC5D, tal) or B-cell maturation antigen (tec), are the first T-cell redirecting bispecific antibodies (BsAbs) approved as monotherapies in Europe and the US for the treatment of pts with triple-class exposed (TCE) RRMM. Use of these novel immunotherapies in earlier LOTs, either with a dual-antigen targeting approach or by enhancing the activity of the BsAb with an IMiD (pomalidomide), may provide deeper, more durable responses and improve pt quality of life. Preliminary data using these combination treatments have shown promising results: in the phase 1b MonumenTAL-2 study (NCT05050097), tal+pomalidomide (tal-P) demonstrated overall response rates (ORRs) of >84% in pts with RRMM with ≥2 prior LOTs and in the phase 1b/2 RedirecTT-1 study (NCT04586426), tal+tec (tal-tec) showed ORRs of >77% in pts with TCE RRMM. MonumenTAL-6 (NCT06208150) is a randomized, open-label, multicenter, phase 3 study comparing the efficacy of tal-P vs investigator's choice of EPd or PVd and tal-tec vs investigator's choice of EPd or PVd in pts with RRMM with 1-4 prior LOTs, including lenalidomide and an anti-CD38 mAb. Study Design and Methods: Eligibility includes pts aged ≥18 years with documented MM per International Myeloma Working Group (IMWG) criteria, with measurable disease at screening, an Eastern Cooperative Oncology Group performance status of 0-2, who have received 1-4 prior LOTs (including lenalidomide and an anti-CD38 mAb in any prior LOT), and have progressive disease on or after their last therapy. Pts with prior exposure to pomalidomide, tec, or GPRC5D-directed therapies are excluded. Approximately 795 pts are randomized 1:1:1 to receive tal-P, tal-tec, or investigator's choice of EPd or PVd. Tal is administered subcutaneously at 0.8 mg/kg every other week (Q2W), and tec is administered subcutaneously at 3.0 mg/kg every 4 weeks (Q4W) following step-up doses of each. Pts are permitted to switch from Q2W to Q4W tal dosing following a confirmed very good partial response or better (≥VGPR) at cycle 5. Pomalidomide, EPd, and PVd are administered per approved dosing schedules. Randomization is stratified by number of prior LOTs (1 vs ≥2), International Staging System stage at screening (I vs II/III), and investigator's choice of treatment (EPd vs PVd). Pts receive study treatment until disease progression, start of subsequent anti-MM treatment, death, intolerable toxicity, withdrawal of consent, or end of study, whichever occurs first. A finite dosing approach is employed for tal and tec. The primary endpoint is progression-free survival (PFS). Secondary endpoints include ORR assessed per IMWG 2016 criteria, ≥VGPR rate, complete response (CR) or better rate, rate of minimal residual disease-negative CR, overall survival, PFS on next LOT, time-to-next treatment, and pt-reported outcomes. This study is actively recruiting, with more than 160 locations in 26 countries. Results will provide insights into the efficacy of the combination of BsAbs in therapeutic strategies that exploit their different mechanisms of action to overcome treatment resistance and improve outcomes of pts with TCE RRMM in earlier LOTs.