Prior Lines Of Therapy Research Articles

Glofitamab monotherapy in patients with heavily pretreated relapsed/refractory (R/R) mantle cell lymphoma (MCL): Updated analysis from a phase I/II study.

7008 Background: Glofitamab, a bispecific antibody with a novel 2:1 (CD20:CD3) format, engages and redirects T cells to eliminate malignant B cells. In a Phase I/II study (NCT03075696), fixed-duration glofitamab monotherapy showed high, durable complete responses (CR) and manageable safety in patients (pts) with heavily pretreated R/R MCL (Phillips et al. ASH 2022). We report updated efficacy and safety data for pts with R/R MCL. Methods: Pts received obinutuzumab pretreatment (Gpt; 1000mg or 2000mg) 7 days before their first glofitamab dose. Glofitamab step-up dosing was given on Cycle (C) 1 Day (D) 8 (2.5mg) and D15 (10mg), and target dose (16mg or 30mg) from C2D1 to C12 as a fixed-duration therapy. Efficacy endpoints were CR, overall response rate (ORR), duration of CR (DOCR), duration of response (DOR) and progression-free survival (PFS). Post-hoc PFS and overall survival (OS) landmark analyses were performed in pts with a CR at end of treatment (EOT). Results: As of Sept 4, 2023, 61 pts were enrolled; 60 received study treatment (1000mg Gpt, n=16; 2000mg Gpt, n=44). Median number of prior lines of therapy was 2 (range: 1–5); 73.3% were refractory to the last line of prior therapy. Median duration of glofitamab therapy was 7.4 months; median number of cycles was 12. Of the 31 pts (51.7%) who received prior Bruton’s tyrosine kinase inhibitor (BTKi) therapy, 29 (93.5%) were BTKi refractory; median number of prior lines of therapy was 3 (range: 1–5); 90.0% were refractory to the last line of prior therapy. At a median PFS follow-up of 17.2 months, ORR and CR rate were 85.0% and 78.3%, respectively. Median DOCR was 15.4 months; the majority of CRs (28/47; 59.6%) were ongoing at data cut-off. Of 19 pts with a CR, 9 had disease progression and 10 died (fatal adverse event [AE], n=8; COVID, n=7; septic shock, n=1). Estimated 12-month DOCR and DOR rates were 71.0% and 66.6%, respectively. Median PFS was 16.8 months. Landmark analyses indicated that most pts with a CR at EOT were alive and progression free 15 months post-EOT (OS rate, 72.7%; PFS rate, 59.2%). Observed efficacy data were consistent across both Gpt cohorts. In post-BTKi pts after a median PFS follow-up of 26.1 months, ORR and CR rate were 74.2% and 71.0%, respectively. Median DOCR was 12.6 months; median PFS was 8.6 months. No new safety signals were observed. Cytokine release syndrome (CRS) remained the most common AE (42/60, 70.0%; Grade 1/2, 58.3%) and was lower in the 2000mg (63.6%) vs the 1000mg (87.5%) Gpt cohort. Glofitamab monotherapy (2000mg Gpt) is currently under investigation in the Phase III GLOBRYTE study (NCT06084936). Conclusions: Fixed-duration glofitamab continues to demonstrate compelling response rates that are maintained beyond EOT, with long-term durability observed in heavily pretreated pts with R/R MCL, including pts with prior BTKi therapy. The safety profile was manageable and CRS mainly low grade. Clinical trial information: NCT03075696 .

Sequential use of PI3K/AKT/mTOR pathway inhibitors alpelisib and everolimus in patients with hormone receptor-positive (HR+) metastatic breast cancer.

1057 Background: Alpelisib (A), a PI3K inhibitor, is FDA-approved with fulvestrant for patients with PIK3CA-mutated HR+/HER2- MBC. Everolimus (E), an mTOR inhibitor, is FDA-approved with endocrine therapy (ET) regardless of PI3K/AKT/mTOR pathway mutation status. The efficacy and safety of sequential treatment with these pathway inhibitors is not well described. Methods: This single-center retrospective cohort study identified patients with HR+/HER2- MBC treated with both A and E sequentially, each in combination with ET, in either order from 2012-2023. We collected information on patient demographics, clinical and pathologic characteristics, treatment history, treatment adverse effects, and dates of disease progression (defined as radiographic or clinical progression leading to treatment change) from medical records. Patients treated first with E then A were categorized as Group 1 and those first with A then E as Group 2. Rates of prior CDK4/6i use were compared between groups with the chi-square test; differences in prior lines of therapy were assessed with the Wilcoxon rank sum test. Median PFS1 (PFS on 1st pathway inhibitor) and PFS2 (PFS on 2nd pathway inhibitor) were computed using the Kaplan-Meier method and the impact of prior treatment on PFS2 between groups was compared using Cox proportional hazards analysis. Results: 115 patients with HR+/HER2- MBC were included in this study. There were 62 (54%) patients in Group 1 and 53 (46%) patients in Group 2. Median prior lines of therapy in the metastatic setting for Group 1 was 4 (range 1-13) and for Group 2 was 3 (range 1-8; p=0.08). Median number of intervening therapies between E and A in Group 1 was 2 (range 0-8) and between A and E in Group 2 was 0 (range 0-4; p<0.001). 34/62 (55%) patients in Group 1 and 45/53 (85%) in Group 2 received prior CDK4/6i ( p<0.001). In Group 1, 49/62 (79%) of patients discontinued E for progression and 13 (21%) discontinued for toxicity. Median PFS1 was 9.2 months (95%CI 5.5-13.0) and PFS2 was 5.0 months (95%CI 4.6-7.9). In Group 2, 34/53 (64%) of patients discontinued A for progression and 19 (36%) discontinued for toxicity. Median PFS1 was 9.3 months (95%CI 7.0-14.0) and PFS2 was 3.5 months (95%CI 3.0-4.1). After adjusting for prior CDK4/6i use and prior lines of therapy (total and intervening), PFS2 was not significantly different between the groups. Genomic information will be included at the time of presentation. Conclusions: This is the largest retrospective study to-date of patients treated sequentially with PI3K/AKT/mTOR pathway inhibitors. PFS was longer with the 1st pathway inhibitor than with the 2nd regardless of sequence. This has implications for optimal integration of capivasertib, an AKT inhibitor, into HR+ MBC treatment. Prospective studies testing optimal sequencing are needed.

ATHENA: A phase 1/2 study of AZD5851, a chimeric antigen receptor (CAR) T-cell therapy directed against GPC3 in adult patients with advanced/recurrent hepatocellular carcinoma (HCC).

TPS2675 Background: Checkpoint inhibitor therapy is the standard first-line treatment for advanced/recurrent HCC, but there is a significant unmet therapeutic need for patients (pts) who progress after first-line treatment. Adoptive cellular immunotherapy may provide a novel treatment option. Glypican-3 (GPC3), a heparan sulfate proteoglycan, is overexpressed by tumor cells in HCC and virtually absent in healthy tissues, making it an ideal target for CAR-T therapy. AZD5851 is an autologous CAR-T product that expresses a CAR specific for GPC3 and a dominant negative (dn)TGFβRII as an armoring strategy. Expression of dnTGFβRII can block TGFβ signaling, protecting CAR T-cells from the immunosuppressive effects of this cytokine. Early clinical data with C-CAR031, a CAR-T product with the same GPC3-specific CAR and dnTGFβRII-armoring transgene as AZD5851, showed promising tolerability and antitumor activity in pts with HCC [1]. ATHENA (NCT06084884) is a first-in-human, single-arm, open-label, multicenter phase 1/2 study to evaluate the safety, tolerability, and antitumor activity of AZD5851 in pts with GPC3+ advanced/recurrent HCC, for whom ≥1 prior line of standard therapy failed or was not tolerable. Methods: Eligible pts are aged ≥18 years with histologically confirmed advanced/recurrent or metastatic and/or unresectable HCC, GPC3+ tumor sample as determined by immunohistochemistry, ≥1 prior line of standard systemic therapy, ≥1 measurable lesion per RECIST 1.1, Child-Pugh A, ECOG PS 0/1, and adequate organ and bone marrow function. Approximately 24 pts will be enrolled in Part A (Phase I, dose escalation) and 50 in Part B (Phase II dose expansion). Pts will undergo apheresis to collect peripheral blood mononuclear cells for AZD5851 production, after which they may receive approved bridging therapy for disease control. Upon successful generation of AZD5851 product, pts will undergo lymphodepletion before receiving a single dose of IV AZD5851. Subsequent follow-up is divided into 3 stages: Stage 1, active follow-up of all pts through 6 months post AZD5851 infusion; Stage 2, further evaluation of pts who have not progressed or started a new anticancer regimen during Stage 1; Stage 3, long-term follow-up for all pts who have received AZD5851. The primary endpoints are to assess the safety/tolerability of AZD5851 (both study parts), and to determine the recommended dose(s) of AZD5851 for expansion and phase 2 trials (Part A). Secondary endpoints include efficacy (objective response rate, best overall response, duration of response, disease control rate, durable response rate, time to response, progression-free survival, and overall survival) and pharmacokinetics. Exploratory endpoints include pharmacodynamic biomarkers and immunogenicity. Enrollment began Nov 2023. 1. Zhang et al. AACR 2023. Abstract CT097. Clinical trial information: NCT06084884 .

Telisotuzumab vedotin monotherapy in patients with previously treated c-Met–overexpressing non-squamous EGFR wildtype advanced NSCLC: Primary analysis of the LUMINOSITY trial.

103 Background: Approximately 25% of patients (pts) with non-squamous (NSQ) EGFR wildtype (WT) NSCLC have c-Met protein overexpression (Ansell et al. 2022 CRUK), which is associated with a poor prognosis (Liang, Wang. Onco Targets Ther. 2020). Telisotuzumab vedotin (Teliso-V) is a c-Met–directed antibody-drug conjugate comprising the mAb telisotuzumab and the microtubule polymerization inhibitor monomethyl auristatin E. The phase 2 LUMINOSITY trial (NCT03539536) aimed to identify the c-Met–overexpressing (OE) NSCLC population best suited to Teliso-V and expand selected group(s) for further evaluation of efficacy. We report on the primary analysis for pts with c-Met OE NSQ EGFRWT NSCLC. Methods: This phase 2, non-randomized, multicenter study enrolled pts with locally advanced/metastatic c-Met OE NSCLC, ≤2 prior lines of therapy (chemotherapy [CTx] + immunotherapy [IO] or sequential CTx + IO), and ≤1 line of chemotherapy. c-Met OE (Ventana MET [SP44] clinical trial assay [CTA]) was defined as ≥25% tumor cells with 3+ staining (high: ≥50% 3+; intermediate [int]: 25 to <50% 3+). Teliso-V was dosed at 1.9 mg/kg IV Q2W. Primary endpoint was overall response rate (ORR) by independent central review per RECIST v1.1. Results: 172 pts with NSQ EGFR WT NSCLC received ≥1 dose of Teliso-V and comprised the safety population; 161 (c-Met high, 78; c-Met int, 83) were included in baseline and efficacy analyses. Median age was 64 yrs (range 33–83), 69% were male, and 70% had ECOG PS 1. 97.5% had prior platinum and 82.0% had prior immune checkpoint inhibitor. Efficacy data are presented in Table below. ORR was 34.6% (c-Met high), 22.9% (c-Met int), 28.6% (overall). Median DOR was 9.0 mo (c-Met high), 7.2 mo (c-Met int), 8.3 mo (overall). Most common any-grade treatment-related AEs (TRAEs) were peripheral sensory neuropathy (30%), peripheral edema (16%), and fatigue (14%). Grade 5 TRAEs occurred in 2 pts (interstitial lung disease, respiratory failure). Conclusions: Teliso-V has shown compelling and durable responses in pts with c-Met OE NSQ EGFR WT NSCLC, especially in pts with c-Met high. Teliso-V had an acceptable safety profile that was clinically manageable, which is consistent with previous data. Clinical trial information: NCT03539536 . [Table: see text]

Longer-term follow-up of patients (pts) receiving prophylactic tocilizumab (toci) for the reduction of cytokine release syndrome (CRS) in the phase 1/2 MajesTEC-1 study of teclistamab in relapsed/refractory multiple myeloma (RRMM).

7517 Background: Emerging data suggest that administering toci prior to bispecific antibodies reduces the incidence of CRS, which may support outpatient therapy initiation. We previously showed that the incidence of CRS with teclistamab, the first approved BCMA×CD3 bispecific antibody with weight-based dosing for the treatment of pts with triple-class exposed RRMM, was reduced from 72% in the overall MajesTEC-1 study population to 26% in a cohort receiving a single dose of toci before the first teclistamab step-up dose. Here, we present an updated analysis with longer-term follow-up. Methods: Pts with triple-class exposed RRMM received subcutaneous teclistamab 1.5 mg/kg weekly in a prospective exploratory cohort or at a comparable fixed dose, following 2 step-up doses. Toci 8 mg/kg was given intravenously ≤4 hours before the first teclistamab step-up dose. CRS was graded per Lee et al ( Blood 2014;124:188-95) and managed per the study protocol. Results: This analysis included 24 pts with median follow-up 8.1 months (range, 0.9–13.2). Median age was 72 years (range, 50–82); 100% had ECOG PS score ≤1; 96% had International Staging System stage I/II; 74% had standard-risk cytogenetics; 21% had extramedullary plasmacytomas; 33% had ≥30% bone marrow plasma cells (biopsy or aspirate). Pts had a median of 4 prior lines of therapy (range, 2–9); 58% were triple-class refractory. CRS occurred in 6 pts (25%; 2 grade 1, 4 grade 2, no grade ≥3); 3 pts each had 1 recurrent CRS event. Median time to CRS onset was 2 days (range, 1–3); median duration was 2 days (range, 2–4). CRS was managed with additional toci in 5/6 pts and steroids in 1/6; all CRS events resolved and none led to teclistamab discontinuation. Most common adverse events (AEs; any grade/grade 3/4) were infections (79%/25%), neutropenia (63%/63%), and anemia (58%/25%); 5 pts had a neurotoxicity AE (grade 1 dizziness; grade 1 headache; grade 1 insomnia; grade 2 headache; grade 2 immune effector cell-associated neurotoxicity syndrome). Overall response rate (n=22) was 73% (59% very good partial response or better). Timing of interleukin (IL)-6 induction in the prophylactic toci cohort was consistent with the phase 1 MajesTEC-1 population, with higher IL-6 levels as observed in other studies of IL-6 receptor-blocking antibodies. Conclusions: Prophylactic toci reduced the incidence of CRS with teclistamab, with a 65% relative reduction vs the overall MajesTEC-1 population (grade 1, 8% vs 50%; grade 2, 17% vs 21%). No new safety signals or impact on response to teclistamab was observed with longer follow-up. Prophylactic toci may be a useful measure to consider when selecting pts for outpatient administration of teclistamab in the future. This approach is being evaluated in the phase 2, multicenter, prospective OPTec study (NCT05972135). Clinical trial information: NCT03145181 / NCT04557098 .

A phase 1 study of fianlimab (anti–LAG-3) in combination with cemiplimab (anti–PD-1) in patients with advanced HNSCC.

6038 Background: Concurrent blockade of LAG-3 may enhance efficacy of anti–PD-1 therapies. We present safety and clinical activity data from a Phase 1 study in patients (pts) with head and neck squamous cell carcinomas (HNSCC) treated with anti–LAG-3 (fianlimab) + anti–PD-1 (cemiplimab). Methods: Two expansion cohorts of adult pts with recurrent and/or metastatic HNSCC with no curative options who were anti–PD-1/PD-L1-naïve (cohort 11) or anti–PD-1/L1-experienced with most recent dose within 3 months (mos) prior to screening (cohort 12) were enrolled. All pts received fianlimab 1600 mg + cemiplimab 350 mg intravenously every 3 weeks (wks) for up to 24 mos. Tumor measurements were performed every 6 wks for 24 wks, then every 9 wks. Results: 15 pts each in cohort 11 and 12 (total N=30; median age: 69 years) were enrolled and treated with fianlimab + cemiplimab as of 04 Oct 2023 data cutoff.For cohorts 11 and 12 respectively, 80% and 87% of pts were male, and 53% and 80% were White. All pts had prior cancer-related systemic therapy. 33% (5/15) and 87% (13/15) of pts in cohorts 11 and 12 had ≥2 lines of prior therapies, respectively. For cohorts 11 and 12, median treatment duration was 12 wks (mean: 41 wks) and 13 wks (mean: 24 wks), and median follow-up was 12 mos and 10 mos, respectively. Grade ≥3 treatment-emergent adverse events (TEAEs) occurred in 47% of pts each in cohorts 11 and 12. Serious TEAEs occurred in 13% and 20% of pts in cohorts 11 and 12, respectively. Treatment-related TEAEs (TRAEs) were reported in 67% of pts in cohorts 11 and 53% of pts in cohort 12. The most common TRAEs (any grade) were hypothyroidism (33%) in cohort 11; and fatigue (20%) and pneumonitis (20%) in cohort 12. Grade ≥3 TRAEs occurred in 7% of pts in cohorts 11 and 13% of pts in cohorts 12. Treatment-related immune-related AEs were reported in 47% and 40% of pts in cohorts 11 and 12, respectively. Treatment was discontinued due to any TEAE in 2 pts in cohort 12. In cohort 12, there was one death due to grade 5 respiratory failure attributable to aspiration pneumonia. RECIST 1.1-based investigator-assessed objective response rate (ORR) was 33% (5 partial responses [PRs]) in cohort 11 and 7% (1 PR) in cohort 12. The disease control rate (DCR) was 47% and 67% in cohorts 11 and 12, respectively. Kaplan–Meier estimation of median progression-free survival was 2 mos (95% CI, 1–14) in cohort 11 and 4 mos (95% CI, 1–7) in cohort 12 pts. Duration of responses were 17, 10, 20, 22, and 20 mos in 5 responders in cohort 11; and 32 mos in 1 responder in cohort 12. Estimated event-free probability at 12 month was 33% (95% CI, 12–56) in cohort 11 and 16% (95% CI, 3–40) in cohort 12 pts. Conclusions: Fianlimab + cemiplimab in pts with HNSCC showed signs of clinical activity with durable responses among pts with anti–PD-1/PD-L1-naïve (cohort 11) and anti–PD-1/L1-experienced (cohort 12), with an acceptable safety profile which warrants further investigation. Clinical trial information: NCT03005782 .

Results of a phase 2 study of evorpacept (E, ALX148), cetuximab (C), and pembrolizumab (P) in patients with refractory microsatellite stable metastatic colorectal cancer (MSS CRC).

3530 Background: Single-agent anti-PD-1/PD-L1 drugs are ineffective in MSS CRC. E is an engineered protein (high-affinity CD47-blocker fused to an inactive IgG Fc region), which blocks the CD47/SIRPα innate immune inhibitory phagocytosis checkpoint expressed on CRC and phagocytes, respectively. Preclinical evidence suggests ECP may be effective in MSS CRC. Methods: This phase 2, single-arm, two-stage, multicenter, investigator-initiated trial of E (15 or 10 mg/kg weekly at dose level [DL] 1 and -1, respectively), C (400 mg/m2 then 250 mg/m2 weekly), and P (200 mg every 3 weeks) in 21-day cycles enrolled patients with MSS CRC, regardless of tumor sidedness and RAS/BRAF status, refractory to ≥ 2 prior lines of therapy, including EGFR inhibitor if indicated (NCT05167409). All patients in both Stage 1 (safety run-in) and Stage 2 (expansion) received ECP until progression or unacceptable toxicity. The co-primary objectives were to determine the recommended dose (RD) of E with CP and objective response rate (ORR) by RECIST v1.1 (by one-sided exact test with α=0.05, H0 p ≤ 3% [historical controls], HA p ≥ 15%; power is 87% with N=48). Results: The safety-evaluable population included 16 patients, of whom 69% were male and median age 53 years. The primary tumor was in the right, left, and transverse colorectum in 31%, 31%, and 6% of patients, and was unknown in 31%. Mutations in KRAS, NRAS, and BRAF genes were present in 38%, 6%, and 0% of patients. The median number of prior lines of therapy was 3, including prior EGFR inhibitor in 44%. In Stage 1, 9 and 3 patients were enrolled at E DL1 and DL-1, respectively. E DL1 was established as the RD for Stage 2, in which 4 patients were enrolled. The most common any-grade treatment-emergent adverse events were headache (32%), fatigue (26%), anemia (21%), diarrhea (21%), dyspnea (16%), abdominal pain (16%), nausea/vomiting (16% each), and acneiform rash (16%). There were two on-study deaths assessed as related to all three study drugs (hemophagocytic lymphohistiocytosis and cytokine release syndrome; 1 each). While both are known associations with checkpoint inhibitors, other significant factors contributing to these event outcomes included cancer progression with high tumor burden in the former and patient decision to transition to comfort care in the latter. In the safety-evaluable population, ORR was 6.3% (1 ongoing partial response, 95% confidence interval [CI] 0.2-30.2%), disease control rate was 12.5% (95% CI 1.6-38.4%), median progression-free survival was 2.6 months (mo; 95% CI 2.1-2.9 mo), and median overall survival was 10.9 mo (95% CI 3.3 mo-infinity). Formal hypothesis testing was not performed. Conclusions: Further dose optimization of ECP is needed to establish a RD in the refractory MSS CRC population. While initial activity was seen, at the DLs evaluated, criteria for study termination were met. Clinical trial information: NCT05167409 .

Efficacy, safety, and determination of RP2D of ABBV-383, a BCMA bispecific antibody, in patients with relapsed/refractory multiple myeloma (RRMM).

7531 Background: MM eventually becomes refractory to current treatments, and new therapeutic options with convenient dosing and improved safety are needed to enhance patient (pt) adherence, access, and outcomes. ABBV-383 is a distinctive next-generation BCMA x CD3 bispecific antibody composed of 2 high-affinity BCMA-binding domains, a low-affinity CD3-binding domain designed to reduce cytokine release syndrome (CRS) risk, and a silenced Fc tail for an extended half-life allowing convenient dosing. ABBV-383 monotherapy has shown promising activity in the ongoing first-in-human phase 1 trial in RRMM (Vij et al. Blood 2023;142[suppl 1]:3378). Here, safety and efficacy results are reported that support the RP2D of 60mg Q4W as the optimal therapeutic ABBV-383 monotherapy dose. Methods: This phase 1 open-label, dose-escalation/expansion trial (NCT03933735) enrolled pts with RRMM who received ≥3 prior lines of therapy with exposure to PI, IMiD, and anti-CD38 mAb. ABBV-383 regimens explored in the expansion phase included 60mg Q4W and 40 or 60mg Q3W. A modified dexamethasone premedication schedule and shortened CRS monitoring period were implemented in the 60mg Q4W cohort for cycle 1. IV ABBV-383 was administered as a flat dose with no step-up schedule. Treatment was continued until disease progression/unacceptable toxicity. Primary objectives were to assess safety, tolerability, PK, PD, and determine the RP2D. Efficacy evaluation was a secondary objective. TEAEs were assessed per CTCAE v5.0 and tumor response per IMWG 2016 criteria. Results: As of May 2023, 220 pts received ABBV-383 (median age: 68 yr [35–92]; median prior therapy lines: 5 [3‒23]). Median FU was 4.1 mo (0.8–5.2) at 60mg Q4W (n=21), 12.2 mo (1.3–34.4) at 40mg Q3W (n=55), and 24.2 mo (0.6–33.4) at 60mg Q3W (n=61). At 60mg Q4W, with the modified premedication regimen, CRS was reported in 43% of pts (38% G1, 5% G2), and ICANS in 5% of pts (G2). In Q3W cohorts, CRS was reported in 71% (40mg; 45% G1, 25% G2) and 70% (60mg; 51% G1, 18% G2, 2% G3) of pts. The incidence of G3/4 neutropenia, anemia, and thrombocytopenia was 14/24/10% at 60mg Q4W, 31/31/16% at 40mg Q3W, and 34/13/13% at 60mg Q3W. G3/4 infections occurred in 10/24/34% of pts at 60mg Q4W, 40mg and 60mg Q3W, respectively. ORR and ≥VGPR were 65/50% at 60mg Q4W, 64/53% at 40mg Q3W, and 60/52% at 60mg Q3W. Corresponding exposure-response (ER) analyses and correlative analyses further supported RP2D determination (separate abstract submissions). Conclusions: The optimal therapeutic dose of 60mg Q4W ABBV-383 monotherapy was selected on the basis of safety, efficacy, and ER analyses. The extended interval of Q4W, with a shortened CRS monitoring period in cycle 1 and no step-up dosing, will improve convenience and reduce the treatment burden for pts. ABBV-383 at 60mg Q4W will be investigated in the registrational phase 3 trial (NCT06158841) in RRMM. Clinical trial information: NCT03933735 .

Belzutifan plus lenvatinib (len) for Chinese patients (pts) with previously treated advanced clear cell renal cell carcinoma (ccRCC): Preliminary results of cohort 1 of the phase 1 LITESPARK-010 study.

4537 Background: Belzutifan, a first-in-class HIF-2α inhibitor, alone or in combination with a VEGFR-TKI, has shown durable antitumor activity in first- and subsequent-line settings of advanced ccRCC. LITESPARK-010 (NCT05030506) is a phase 1, 2-cohort, open-label study of belzutifan + len, with or without pembrolizumab, in Chinese pts with advanced ccRCC. We present preliminary results cohort 1. Methods: Chinese adults with histologically confirmed ccRCC who had 1-3 prior treatment regimens received belzutifan 120 mg PO QD for 3 wk followed by belzutifan 120 mg + len 20 mg PO QD until intolerable toxicity, disease progression, or pt withdrawal. The study included a dose-limiting toxicity (DLT) phase of 21 days after the start of combination treatment. Dual primary end points were safety and PK. Secondary end points included ORR, DOR, and PFS per RECIST v1.1 by investigator assessment and OS. Results: As of August 29, 2023, 24 pts were enrolled in cohort 1 and 23 received combination treatment; 1 pt discontinued in the monotherapy period because of treatment with non-study anti-cancer therapy. Median age was 61 years, 17 pts (71%) were male, and 14 (58%) had intermediate/poor IMDC risk. 14 pts (58%) received 1 prior line of therapy and 10 (42%) received ≥2 prior lines. Five pts (21%) received prior therapy with a PD-(L)1 inhibitor. As of the data cutoff date, 11 pts (46%) remained on treatment. Median follow up was 14.4 mo (range, 1.6-22.1). Ten pts were evaluated in the DLT phase, and 1 experienced a DLT (grade 2 treatment-related transient ischemic attack). All 24 pts (100%) experienced a treatment-related AE (TRAE) of any grade, most commonly anemia (100%) and proteinuria (88%). Grade 3 or 4 TRAEs occurred in 17 pts (71%), most commonly anemia (29%) and hypertension (29%). One pt (4%) experienced grade 3 hypoxia. No pts died (grade 5) due to a TRAE. After a single dose of belzutifan monotherapy, median Tmax was 1.8 h (range, 0.6-8.0), geometric mean AUC0-24 was 22,400 h·ng/mL (90% CI, 19,600-25,500), and geometric mean Cmax was 1640 ng/mL (90% CI, 1490-1820). Steady-state concentration was reached after 14 days of belzutifan monotherapy treatment; the accumulation ratio of AUC0-24 was 1.7 (90% CI, 1.5-1.9). Belzutifan + len treatment had similar PK to belzutifan monotherapy. In all 24 pts, confirmed ORR was 50% (95% CI, 29-71; all PRs). Median DOR was not reached (NR; range, 3.5-20.4+ months); 50% of responders remained in response for ≥12 mo per Kaplan-Meir estimate. Median PFS was 13.7 mo (95% CI, 8-NR) and median OS was NR (95% CI, NR-NR). The 12-mo PFS and OS rates were 57% and 75%, respectively. Conclusions: Preliminary data from the belzutifan + len showed promising antitumor activity in Chinese pts with previously treated ccRCC. The safety of belzutifan 120 mg + len 20 mg was consistent with the safety profiles of the individual drugs. Clinical trial information: NCT05030506 .

Real world (RW) study of patients (pts) with relapsed or refractory (RR) blastic plasmacytoid dendritic cell neoplasm (BPDCN) treated with tagraxofusp (TAG).

e18533 Background: BPDCN is characterized by clonal expansion of plasmacytoid dendritic malignant cells that express CD123 and other markers. TAG, a CD123-directed therapy, is the only drug approved to treat BPDCN (US/EU). In August 2019, a European Named Patient Program (NPP) started to ensure pt access to TAG. To assess RW safety and efficacy of TAG treatment in RR BPDCN, a pt population with a very poor prognosis, we retrospectively analyzed data from pts enrolled in the NPP. Methods: Pts with RR BPDCN received TAG 12 mcg/kg qd on days 1-5 (or by day 10) of each 21-day cycle. The first TAG cycle was given inpatient with outpatient treatment allowed thereafter. Clinicians received training on capillary leak syndrome (CLS) monitoring and management guidelines. Primary endpoints were complete response (CR) after 2-3 cycles and CLS incidence and grade (G). Secondary endpoints included number of pts bridged to stem cell transplantation (SCT), progression-free survival (PFS), overall survival (OS), best overall response rate (ORR), duration of response (DOR), and safety. Results: Of 18 pts with RR BPDCN (median age 66 y [29–83]; 89% male), 67% had received 1 prior line of therapy and 28% 2 prior lines. At initial diagnosis, pts had disease involvement in bone marrow (89%), skin (67%), and lymph nodes (61%). Median time from initial diagnosis to TAG was 7.4 mo (1–27). At a median follow-up of 8 mo, pts received a median of 2 (1–5) TAG cycles. In 15 pts with ≥1 tumor assessment, the ORR was 67% (40% CR and 27% partial response [PR]) with a median DOR of 5 mo (95% CI, 3.0–not estimable [NE]). All 18 pts had a median PFS of 4.3 mo (95% CI, 1.4–12.9) and median OS of 8.6 mo (95% CI, 3.6–NE). In 15 pts with ≥1 tumor assessment, 6 (40%) pts were bridged to SCT and had durable posttransplant responses (CR 83%; PR 17%) with median DOR, PFS, and OS not reached. CLS was mostly mild to moderate in severity; 61% of pts had CLS in cycle 1 and only 1 pt had an event in cycle 2. The median time to CLS resolution was 4 days. Other than CLS, TAG-related nonhematologic G3-4 adverse events (AEs) and serious AEs (SAEs) occurred in 44% of pts, all during cycle 1, with hepatic cytolysis, pneumonia and tumor lysis syndrome reported in 2 (11%) pts each. Grade 3-4 thrombocytopenia and pancytopenia were reported in 2 (11%) pts each. Median time to resolution was 5 days for the nonhematologic G3-4 AEs/SAEs and 18 days for thrombocytopenia. Two (11%) pts had G3-4/SAE infections. There were no treatment-related deaths. Conclusions: TAG induced fast and durable responses, and a high response rate, in RR BPDCN pts, with prolonged survival in a poor prognosis population, where historic treatments show limited efficacy. There were no new safety signals. With proper selection, monitoring, and directed intervention, CLS is manageable, usually mild, limited to the first cycle, and does not recur. These RW results support the use of TAG in pts with RR BPDCN.

Efficacy and safety of sigvotatug vedotin, an investigational ADC, in NSCLC: Updated phase 1 results (SGNB6A-001).

8521 Background: Integrin beta-6 (IB6), a tumor-associated membrane protein, plays an important role in pathogenesis and invasiveness and its expression correlates with poor outcomes. Sigvotatug vedotin (SV), formerly called SGN-B6A, is an IB6-directed ADC with encouraging activity in NSCLC in the Ph 1 study SGNB6A-001 (NCT04389632) (Hollebecque 2023). Here, we report updated efficacy and safety of SV in NSCLC. Methods: SGNB6A-001 is an open-label, multicenter, Ph 1 study evaluating the safety, pharmacokinetics (PK), and antitumor activity (cORR, DOR, and PFS per RECIST v1.1, and OS) of SV in patients (pts) with advanced solid tumors. Multiple dose regimens were explored during dose escalation (Part A). Dose expansion (Part B) is ongoing with selected regimens in various tumors including NSCLC. Parts C and D will evaluate SV in combination with pembrolizumab in NSCLC and HNSCC. Eligible pts had no therapeutic options (Part A) or had received platinum-based and anti-PD-(L)1 therapy unless contraindicated (Part B) and were dosed with the SV expansion regimens on D1 and D8 in a 21-day cycle (2Q3W; 1.2/1.25 mg/kg total body weight [TBW]) or D1 and D15 in a 28-day cycle (2Q4W; 1.5 mg/kg TBW, 1.8 mg/kg adjusted ideal body weight [AiBW]). Results: As of 01-Dec-2023, 306 pts had received SV; 113 pts with NSCLC received expansion regimens in Parts A and B. Prior lines of therapy and efficacy data for all pts with NSCLC and select subgroups are summarized in the table; cORR was 19.5% (95% CI, 12.6-28.0) in all pts with NSCLC and 32.5% (95% CI, 18.6-49.1) in pts with non-squamous (non-Sq)/taxane-naive NSCLC. Additional time-to-event data will be presented. Rates of TEAEs, ≥G3 TEAEs, SAEs, and TEAEs leading to discontinuation were 98.2%, 46.0%, 33.6%, and 13.3% in pts with NSCLC, and were consistent in all treated pts. The most common ≥G3 TEAEs in pts with NSCLC were dyspnea (9.7%), fatigue (7.1%), and neutropenia (5.3%). One pt with NSCLC had a treatment-related death (pneumonitis). PK variability across weight groups was lowest with 1.8 mg/kg AiBW 2Q4W. Conclusions: SV continues to demonstrate encouraging antitumor activity and a manageable safety profile in pts with NSCLC. Data at 1.8 mg/kg AiBW 2Q4W support initiation of the Ph 3 SGNB6A-002 study in 2/3L NSCLC (NCT06012435) and combination with pembrolizumab in earlier settings. Clinical trial information: NCT04389632 . [Table: see text]

Pooled analysis by best confirmed response to trastuzumab deruxtecan (T-DXd) in patients (pts) with HER2+ metastatic breast cancer (mBC) from DESTINY-Breast-01, -02, and -03.

1023 Background: DESTINY-Breast (DB)-01, -02, and -03 evaluated T-DXd in pts with HER2+ mBC who received ≥1 prior line of therapy. These studies showed confirmed objective response rates by independent central review (ICR; blinded for DB-02 and -03) of 62%, 70%, and 79% and complete response (CR) rates of 7%, 14%, and 21%, respectively, with T-DXd. We report a pooled analysis according to pts’ best confirmed response in DB-01, -02, or -03. Methods: Endpoints included best confirmed response per (blinded) ICR ([B]ICR) based on RECIST v1.1, duration of response (DoR), progression-free survival (PFS) by (B)ICR, overall survival (OS), and safety. Results: The median (range) duration of T-DXd treatment for pts with a CR, partial response (PR), or stable disease (SD)/progressive disease (PD) was 27.4 (4.5-45.1) mo, 14.0 (2.1-39.3) mo, or 6.2 (0.7-40.1) mo, respectively. Of 834 evaluable pts assigned to T-DXd in DB-01, -02, or -03, 125 (15.0%) had a CR, 477 (57.2%) had a PR, and 232 (27.8%) had SD/PD. Pts with CR had a median of 2 prior regimens (range, 1-11) in the metastatic setting, whereas pts with PR or SD/PD had a median of 3 prior regimens. As shown in the Table, pts with CR had more favorable PFS and OS outcomes vs pts with PR or SD/PD. The proportion of pts with drug-related, serious treatment-emergent adverse events (TEAEs) was numerically lower in pts with CR (8.0%) than those with PR (12.4%) or SD/PD (15.5%). Pts with CR also had numerically lower rates of drug-related TEAEs associated with T-DXd discontinuation (14.4% vs 17.8% or 16.8%) and adjudicated drug-related interstitial lung disease (ILD)/pneumonitis (8.8% [0 fatal] vs 15.1% [2 fatal] or 11.6% [5 fatal]) and longer median time to first ILD onset (461 days vs 211 or 125 days) vs pts with PR or SD/PD. Conclusions: Pts treated with T-DXd benefited from durable responses resulting in prolonged PFS and OS, especially those with a CR. Despite longer treatment duration in responders, safety remained generally manageable and did not result in a higher percentage of pts with TEAEs over time. These results further support the use of T-DXd across broad pt groups with HER2+ mBC. Clinical trial information: NCT03248492 , NCT03523585 , NCT03529110 . [Table: see text]

A phase I study of irinotecan combined with BAY1895344 (ATR inhibitor) in advanced solid tumors: Results of ETCTN 10402 dose escalation.

3077 Background: ATR protein kinase is activated by replication stress and recruited to stalled forks or single strand DNA defects in various cancers. The topoisomerase-I (Top1) inhibitor irinotecan induces DNA damage. The ATR inhibitor BAY1895344 (elimusertib) has demonstrated cytotoxic potential in SCLC and GI cancer xenografts when combined with Top1 inhibitors . Methods: This phase Ia trial assessed elimusertib in combination with irinotecan in adult patients with refractory advanced solid tumors for whom irinotecan can be considered standard care. Patients with previous irinotecan exposure were excluded. Two dosing schedules were used: 1) Biweekly - irinotecan IV (starting at 150 mg/m2) D1 + elimusertib (starting dose 20 mg PO BID) D1,D2 (cycle=14 days); 2) Weekly - irinotecan (starting at 50 mg/m2) IV on D1,8,15 with elimusertib (starting at 20 mg PO daily) on D2,D3,D9,D10 and D16,D17 (cycle=21 days). Dose escalation utilized a 3+3 design. Primary objectives were to assess safety and tolerability and estimate the maximum tolerated dose (MTD) and recommended phase 2 dose (RP2D). Secondary objectives included estimating pharmacokinetic (PK) profiles and assessing anti-tumor activity. Results: A total of 21 patients were enrolled in dose escalation (N=9 [Biweekly] and N=12 [Weekly], median age 58 and 2 lines of prior therapy. For the Biweekly cohort: 3/3 patients enrolled at dose level (DL) 1 experienced hematologic dose-limiting toxicity (DLT); 6 patients received DL-1 without any DLTs. The weekly regimen escalation comprised of 12 patients: 6 enrolled in DL1 with 2/6 having hematologic DLT and 5/6 unable to complete ≥75% of cycle 1 dosing; 6 enrolled in DL-1 with no DLTs observed. Notable grade 3+ treatment-related adverse events and summary best response are summarized (Table 1). The majority of evaluable patients in both schedules had initial disease control (56% [biweekly] and 67% [weekly]). One confirmed partial response was seen in the biweekly RP2D. Median progression-free survival was 2.1 mo [biweekly] and 2.5 mo [weekly]. PK results will be presented at time of meeting. Conclusions: Both RP2D and MTD of elimusertib in combination with irinotecan were reached for both dosing schedules: irinotecan 150 mg/m2 IV D1 + elimusertib 10 mg BID PO D1,D2 (biweekly) and irinotecan 25 mg/m2 IV on D1 + elimusertib (20 mg PO daily) on D2,D3 (weekly). Dose escalation was notably limited by myelotoxicity. Due to sponsor decision, the study was halted prior to planned expansion but the concept of ATR + topo I combination remains scientifically relevant. Clinical trial information: NCT04514497 . [Table: see text]

A phase I/Ib study of the aurora kinase A inhibitor alisertib in combination with osimertinib in advanced osimertinib-resistant EGFR-mutated lung cancer.

8572 Background: The third-generation Epidermal Growth Factor Receptor (EGFR) tyrosine kinase inhibitor (TKI) osimertinib is effective for the treatment of advanced EGFR-mutated lung adenocarcinoma (LUAD), however treatment resistance invariably occurs. We previously identified Aurora Kinase A (AURKA) activation as a mechanism of resistance to osimertinib. Alisertib is an oral, selective, small-molecule inhibitor of AURKA. We evaluated the combination of alisertib with osimertinib in a phase I/Ib study of patients with advanced EGFR-mutated LUAD who experienced disease progression on prior treatment with osimertinib monotherapy. Methods: 21 total patients were treated in an open-label, single-center phase I trial (NCT04085315). 10 patients were treated in a 3+3 dose escalation phase with alisertib using an intermittent dosing strategy of 30 mg (n = 6) or 40 mg (n = 4) twice daily (BID) on days (d) 1-3, 8-11, and 15-17 of a 28-day cycle in combination with osimertinib 80 mg daily. 11 additional patients were treated at the 30 mg alisertib intermittent dosing schedule in combination with osimertinib 80 mg daily in a Phase Ib dose expansion. Primary endpoints were safety, maximum tolerated dose (MTD), and recommended phase II dose (RP2D) of the alisertib and osimertinib combination. Secondary endpoints were investigator-assessed objective response rate (ORR) by RECIST 1.1 criteria, depth of response (DoR), disease control rate (DCR) for at least 12 weeks, progression-free survival (PFS) and overall survival (OS). Results: 21 patients with stage IV EGFR-mutated LUAD (76.1% exon 19 deletion; 14.3% L858R; 9.5 % L861Q) who had progressed on osimertinib were enrolled. 10 (47.6%) patients had received only first-line osimertinib, while 11 (52.3%) had received ≥ 2 lines of prior therapy. Common treatment-related adverse events were neutropenia (42.9%), anemia (42.9%), and diarrhea (38.1%). 2 patients had dose limiting toxicities from grade 4 neutropenia at the alisertib 40mg BID dose level. 2 patients had serious adverse events related to the study drugs, including grade 3 constipation and grade 4 anemia. There were no treatment-related deaths. Intermittent alisertib 30 mg BID with osimertinib 80 mg daily was the MTD and R2PD. ORR for all enrolled patients was 9.5% (95% CI: 1.2% to 30.4%), DCR was 81% (95% CI: 58.1% to 94.6%), and median DoR was -4 % (95% CI: -15% to 10%). The median PFS was 5.5 months (95% CI: 3.7 – 13.2 months) and median OS was 23.5 months (95% CI: 11.9 months – NR). Conclusions: Intermittent dosing of alisertib 30 mg BID in combination with osimertinib 80 mg daily demonstrated no dose limiting toxicities and was identified as the RP2D. While ORR was < 10%, DCR was > 80% and the median PFS was 5.5 months. These results are comparable to other emerging therapies for patients with advanced osimertinib resistant EGFR-mutated LUAD and warrants further exploration. Clinical trial information: NCT04085315 .

Exploring the safety and efficacy of GT201 as a first-in-class autologous tumor-infiltrating lymphocyte monotherapy in advanced solid tumors.

2547 Background: GT201, featuring a membrane bound IL-15 stably expressed on tumor-infiltrating lymphocytes (TIL), aims to augment TIL persistence and function as well as ameliorate immune suppression within the tumor microenvironment, offering potential for durable responses in advanced solid tumor patients. We present data from 7 patients enrolled in an open-label, single-arm, multicenter clinical study (NCT05729399), investigating the safety profile and efficiency trend of GT201 therapy. Methods: The GT201 phase 1 trial is designed with the primary endpoint of DLT evaluation and the secondary endpoint of measuring preliminary efficacy parameters including overall response rate (ORR), disease control rate (DCR), progression-free survival (PFS), duration of response (DOR, and overall survival (OS) following the RECIST v1.1. Results: As of January 22, 2024, a cohort of 7 pts has been enrolled in the study, with a median age of 48 and a median of 3 prior lines of therapy. Among these patients, 1 pt has a history of bone metastases, 2 pts have a history of liver metastases, and 1 pt has a history of brain metastases. Following the standard FC lymphodepletion, pts underwent infusion with GT201 at doses ≥ 5x109 total viable cells. Five pts subsequently received IL-2 as part of the treatment protocol. Treatment-related AEs were observed in ≥ 50% of pts with no grade≥3 AEs. Grade ≥ 3 AEs related to FC lymphodepleting chemotherapy and IL-2 included decreased lymphocyte count, decreased neutrophil count, and decreased white blood cell count, pyrexia and increased heart rate. Notably, all grade ≥3 AEs were either recovered or downgraded to grade ≤ 2 within 14 days. Among the 7 response-evaluable patients across various indications, including Non-Small-Cell-Lung Cancer (NSCLC), melanoma malignant, cervical cancer, and ovarian cancer, 3 patients (42.9%) achieved a confirmed partial response (PR), and 2 patients (28.6%) demonstrated stable disease (SD) as their best response. Notably, among the NSCLC subgroup, disease control (SD ≥ 24 weeks or any PR) was observed in all 3 pts (3/3, 100 %). GT201 cells can be detected in all patients receiving treatment, indicated by both staining IL15RA protein on peripheral T cells and measuring the transgene copy number in peripheral white blood cells. GT201 cells expanded robustly in patients and persist in peripheral blood beyond at least 6 months post cell infusion. Conclusions: In patients with heavily pretreated advanced or metastatic solid tumor, GT201, when infused after FC lymphodepletion and followed by high dose IL-2, exhibits a manageable safety profile. Notably, GT201 has demonstrated a favorable clinical profile in NSCLC, with an encouraging objective response rate, response durability, and no GT201-treatment related grade≥3 AEs. Clinical trial information: NCT05729399 .

Glofitamab combined with poseltinib and lenalidomide for relapsed/refractory diffuse large B cell lymphoma: Interim analysis of GPL study.

7066 Background: Despite advanced treatments, including chimeric antigen receptor therapy (CAR-T), a significant proportion of patients succumb to relapsed and refractory diffuse large B cell lymphoma (R/R DLBCL). In vitro experiments suggest synergism between BTK inhibitor (BTKi) and T-cell engager, we initiated a multicenter trial of poseltinib and glofitamab in combination with lenalidomide in R/R DLBCL. Methods: This is a phase II, open label, single arm study aiming to enroll 76 participants with adult R/R DLBCL patients (NCT05335018). Patients refractory to frontline therapy or those who failed more than two lines of therapies were enrolled. Previous anti-CD19 CAR-T was allowed, while previous CD20 T-cell engager was not permitted. Participants received glofitamab (In cycle 1, dose is increased weekly from 2.5mg to 10mg, and after cycle 2, 30mg is administered on Day 1), lenalidomide (20mg daily from Day 1-14), and poseltinib (40mg twice daily from Day 1-21) (GPL) every 3 weeks for a total of 12 cycles(induction). Maintenance with poseltinib and lenalidomide for 17 cycles were given to patients after induction period. The primary endpoint is overall response rate (ORR), with secondary endpoints including duration of response (DoR), complete response rate (CRR), progression free survival (PFS), overall survival (OS), and incidence of treatment related adverse events. Results: No safety signals were observed in the safety cohort (n=6, 3+3 design). As of November 2023, 37 patients (median age 71) have been treated with GPL, with a median follow up duration of 3.6 months. In prior lines of therapy, 13 patients (35.1%) received treatment more than 2, and 26 patients (70.3%) were with Ann Arbor stage III/IV and 7 patients (18.9%) were refractory to frontline treatment. Previously, 3 patients (8.1%) received CAR-T. Out of 28 evaluable patients, ORR was 89.3%, with CRR of 42.9%. Six-month OS and PFS rate were 81% and 55%. DoR at 6 months was 66%. Neutropenia (45.9%) was the most common grade(gr) 3-4. Three patients (8.1%) died of gr5. There was 1 case (2.7%) of gr3 atrial fibrillation and gr1 bleeding. No incidence of gr3 or above liver/renal toxicity were observed. Overall, 3 patients (8.1%) discontinued GPL treatment due to toxicity, and cytokine release syndrome was observed in 7 patients (18.9%) and only 2 patients (5.4%) were gr3-4. Conclusions: Interim analysis indicates that the GPL regimen is an effective and safe regimen for R/R DLBCL patients. High response rates observed support further investigation of GPL for potential synergism between T-cell engagers and BTKi. This multicenter study is actively recruiting patients and is set to complete enrollment within this year. Clinical trial information: NCT05335018 . [Table: see text]

Outcomes in patients (pts) with relapsed/refractory (R/R) diffuse large B cell lymphoma (DLBCL) treated with systemic therapy from real world experience (ORCHID) study.

e19067 Background: Odronextamab, an off-the-shelf CD20×CD3 bispecific antibody, has shown compelling efficacy (objective response rate [ORR] 52%, complete response [CR] rate 31.5%) and a generally manageable safety profile in pts with heavily pretreated R/R DLBCL in the single-arm ELM-2 trial (NCT03888105; Ayyappan et al. ASH 2023). We evaluated outcomes in pts with R/R DLBCL treated with currently available third-line or later (3L+) therapies in a real-world setting (ORCHID; NCT05338892) to better evaluate results from ELM-2 in the absence of a randomized control arm. Methods: ORCHID is a multicenter, retrospective, observational study, using electronic medical record or research databases, of pts with R/R DLBCL who have received ≥2 prior lines of therapy (LoTs; including an anti-CD20 and an alkylator) and initiated 3L+ systemic therapy for DLBCL between January 1, 2015 and June 30, 2021. After applying similar eligibility criteria to those in the ELM-2 trial, inverse-probability of treatment weighting (IPTW) was used to balance key prognostic variables between the trial and real-world cohorts. Pts were followed from the start of qualifying LoT until death, end of study period (December 31, 2021), or loss to follow up, whichever occurred first. The primary endpoint was ORR per Lugano criteria assessed by independent central review (ICR). Secondary endpoints included ICR-assessed CR rate, disease control rate (DCR), progression-free survival (PFS), duration of response (DOR), and overall survival (OS) (see Thieblemont et al. ASH 2022). Results: Pts in ORCHID (N=148) generally had less severe disease than trial pts prior to IPTW. The most commonly used regimens were anti-CD20 based therapies, CAR T, and chemotherapy alone. The IPTW cohort had a median age 65 y, 79% Ann Arbor stage III/IV, 66% primary refractory, 88% refractory to last LoT, and median (range) prior LoT: 2 (2–6). In the IPTW cohort, ORR was 44%, CR 18%, and DCR 50%. Median (m) PFS (mPFS), DOR (mDOR), and OS (mOS) were 7.2, 9.0, and 10.8 mo, respectively. Given the lack of regular scans in routine practice (47% of pts had only one ICR response assessment over the study period), sensitivity analysis that considered subsequent treatment as progression resulted in shorter mPFS (4.6 mo) and mDOR (6.1 mo). In the majority of LoTs initiating non-CAR T therapy (n=111), ORR was 33%, CR 15%, DCR 43%. The mOS in non-CAR T group was 7.5 mo and was not reached in those intended for CAR T. Conclusions: Pts in the ORCHID study, especially those who did not receive CAR Ts, had markedly lower response rates than those in the R/R DLBCL cohort of ELM-2. Despite prior failure, most pts still received an anti-CD20 based regimen in 3L+ setting in routine practice, highlighting the need for treatment options with different mechanisms of action that provide deep and durable responses and improve outcomes in this pt population. Clinical trial information: NCT05338892 .

Phase 1b study of tarlatamab in de novo or treatment-emergent neuroendocrine prostate cancer (NEPC).

5012 Background: NEPC is an aggressive form of prostate cancer with poor prognosis and no standard treatment approach. NEPC can be characterized by late, treatment-emergent transformation from adenocarcinoma to high-grade neuroendocrine carcinoma (NEC), in 10–15% of mCRPC patients (pts). DLL3 is overexpressed in high-grade NECs, including NEPC, and minimally expressed on normal tissue. Tarlatamab, a bispecific T-cell engager immunotherapy with clinical activity in small cell lung cancer (SCLC), binds DLL3 and CD3 resulting in T-cell mediated tumor lysis. Here, we report primary analysis data of tarlatamab in NEPC (NCT04702737). Methods: This is an open-label phase 1b study evaluating tarlatamab monotherapy in adult (≥18 years [y]) pts with metastatic de novo or treatment-emergent NEPC by histologic, genomic, or immunohistochemistry (IHC) criteria. The starting dose was the highest safe and tolerable dose in the phase 1 SCLC trial (NCT03319940). Safety was the primary objective; anti-tumor activity and pharmacokinetics were secondary objectives. Exploratory analysis of DLL3 expression was assessed by IHC using the Ventana SP347 assay. Results: As of 28 March 2023, 40 pts received ≥1 tarlatamab dose (1 mg step dose, 100 mg target dose). Median (range) age was 64.5 (43–83) y, prior lines of therapy was 3 (1–9), prostate specific antigen at baseline was 0.2 (0.0–5000.0) μg/L. Treatment-related adverse events (TRAE) occurred in all patients, with no fatal TRAE. Most common TRAEs were cytokine-release syndrome (CRS; 65.0%), pyrexia (52.5%) and dysgeusia (42.5%). CRS occurred primarily in treatment cycle 1; events were mostly grade 1–2 (one grade 3 event). Treatment discontinuation due to TRAE was low (7.5%). Tarlatamab serum exposures were consistent with tarlatamab SCLC studies. Objective response rate (ORR) per Response Evaluation Criteria in Solid Tumors version 1.1 (RECIST v1.1) was 10.5% (95% CI, 2.9, 24.8); median progression free survival (mPFS) was 1.9 months (m) (95% CI, 1.7, 3.5). Retrospective DLL3 IHC analysis showed that 18 of 32 (56.3%) biopsy evaluable pts had ≥1% DLL3 tumor positivity (DLL3+). As of 24 January 2024, ORR in DLL3+ pts was 22.2% (95% CI, 6.4, 47.6); durations of response in the 4 pts with response were 25.8 m, 9.2 m, 5.5 m, 3.7 m; mPFS in DLL3+ pts was 3.75 m (95% CI, 1.87, 11.01). Efficacy is shown in Table. Conclusions: Findings from this phase 1 study of tarlatamab in pts with NEPC demonstrated manageable safety with encouraging anti-tumor activity in DLL3 expressing NEPC. Further investigation is ongoing. Clinical trial information: NCT04702737 . [Table: see text]

Clinical outcomes from a phase I clinical trial of a novel oncolytic virus VG161 in patients with hepatocellular carcinoma (HCC) refractory after 2 prior lines of therapy including checkpoint inhibitors (CPI).

4105 Background: This study aims to investigate the safety and anti-tumor activity of VG161 expressing IL12, IL15/IL15 receptor α unit, and PD-L1 blocking peptide in patients with HCC refractory to standard therapies. Methods: The study was conducted as a multicenter phase I trial with fast titration and 3+3 dose escalation part (A) and expansion part (B), which enrolled patients with primary liver cancer refractory to standard therapies. Patients in part A were dosed in 5 cohorts on days 1, 2 and 3 by image-guided intratumoral injections with dosing ranges from 1.0×10^8 to 5×10^8 PFU per 28 days treatment cycles. Part B used a single arm Simon's two-stage design at the recommended phase 2 dose (RP2D). The study endpoints were safety, and efficacy assessed by objective response rate (ORR) and Disease Control Rate (DCR) by RECIST1.1 and mRECIST (HCC), PFS and OS. Pretreatment HCC tumor samples were collected and analyzed by RNAseq. Results: 44 patients including 40 HCC (Male/Female: 37/3; median age: 58years) were dosed and no DLTs were reported. The most common Treatment-Related Adverse Events (TRAEs) was fever, which was resolved with symptomatic treatment. RP2D was determined as 1ⅹ10^8 PFU daily on day 1, 2 and 3 of each cycle. Of 40 HCC patients, 35 failed after 2 prior lines of therapy and were eligible for tumor assessment. ORR was 17.14% (6/35), DCR was 60.00% (21/35). The median PFS and OS were 2.90 (95%CI: 1.85-3.95) and 9.40 (95%CI: 0.47-18.33) months respectively. Statistically significant OS prolongation was observed in a subgroup of 22 HCC patients who progressed after receiving at least 3 months of CPI (PreCPI>3 m) as compared to those who received CPI for ≤3 months (PreCPI ≤ 3 m). The median OS was 17.30 months (95%CI: 5.35-29.25) vs. 7.40 months (95%CI: 5.11-9.69), HR: 0.32 (95%CI: 0.10 to 0.98) (p<0.05). Patients who received targeted or CPI therapies after VG161 survived longer than those who did not receive any anticancer treatment although they all previously failed such therapies [20.10 months (95%CI: 13.19-27.01) vs. 8.80 months (95%CI: 6.34-11.26), HR: 0.30 (95%CI: 0.10-0.88), P<0.05]. PreCPI>3 m and anti-cancer treatment after VG161 were the 2 independent factors with significant impact on OS (P<0.05). A gene signature was identified based on RNAseq data which predicted the prolonged OS in the study patients (P<0.01) but not in patients retrieved from TCGA database. Conclusions: VG161 was well tolerated and demonstrated comparable ORR and DCR with other CPIs data in 2L HCC. VG161 also prolonged survival in a subgroup of patients identified by prior treatment or gene signature, supporting further studies with enrichment of patients who may benefit from the treatment. The implications of pre/post VG161 CPI treatment on OS underscore a combination strategy for improving outcomes. Clinical trial information: NCT04806464 .

Safety and efficacy of JSKN003 in patients with advanced/metastatic solid tumors: A first-in-human, dose-escalation, multicenter, open-label, phase I study.

3038 Background: JSKN003 is a biparatopic HER2-directed ADC conjugated to a topoisomerase I inhibitor with an average DAR 4. Preclinical studies showed that JSKN003 had a good serum stability and strong anti-tumor activity. Hence JSKN003 could be effective in HER2 expressing tumors with a potentially broader therapeutic window. Methods: JSKN003-101 is a first-in-human, dose-escalation and -expansion study in Australian pts with advanced solid tumors. Pts (ECOG 0-1) with histologically documented HER2-expressing (HER2-positive defined as IHC 2+ or 2+/ISH+, HER2 low defined as IHC 1+ pr 2+/ISH-) or HER2-mutation by local testing who failed prior systemic therapies were recruited and received JSKN003 monotherapy intravenously Q3W. The objectives were safety, tolerability, MTD or RP2D, PK, and preliminary antitumor activity. Here the results from dose-escalation part were reported. Results: As of 15 Dec 2023, 32 pts were enrolled and received JSKN003 across 7 dose levels (1.0-8.4 mg/kg, Q3W). Among the 32 pts, 9 were IHC 1+, 16 were IHC 2+, and 7 were IHC 3+. Most pts (22/32, 68.8%) received ≥ 3 prior lines of therapy. The median duration of treatment was 15.8 (range, 6-54) weeks, and 19 pts (59.4%) remain on treatment. TRAEs occurred in 27 pts (84.4%) and 2 pts (6.3%) in 4.2mg/kg and 7.3mg/kg experienced grade 3 TRAE (anemia and fatigue); the most common TRAEs were diarrhea (62.5%) and nausea (50.0%), which were all grade 1-2. Only 1 pt experienced ILD/pneumonia (7.3mg/kg, grade 2). To date, no DLT events were found yet, and no TRAE led to death or treatment discontinuation. MTD has not been reached in 8.4 mg/kg. Following a single dose, exposures (Cmax and AUC) of JSKN003 and released TOP1i increased proportionally over a dose range of 4.2 mg/kg to 8.4 mg/kg. T1/2 of JSKN003 is approximately 5-6 days for 6.3 mg/kg and higher doses and increases with dose escalation. Accumulation of JSKN003 was minimal within the range of 1.1-1.5. The exposure of released payload was significantly lower than JSKN003 ADC, demonstrating the stability of the JSKN003 in circulation. All pts had at least one post-baseline tumor assessment. 16 pts achieved PR per RECIST 1.1 by investigator. Thus, ORR and DCR was 50.0% (95%CI: 31.9%, 68.1%) and 90.6% (95%CI: 75.0%, 98.0%), respectively. The ORR in pts with IHC 1+, 2+ and 3+ was 55.6% (5/9), 37.5% (6/16), and 71.4% (5/7), respectively. As for the efficacy of the HER2-positive and HER2-low breast cancer, the ORR was 80% (4/5) and 40.0% (4/10), respectively. Conclusions: JSKN003 was well tolerated with encouraging preliminary antitumor activity in heavily pretreated pts with advanced/metastatic solid tumors, especially in pts with HER2 expressed tumors. As of the cut-off date, no DLT was observed, MTD has not been reached yet. Clinical trial information: NCT05494918 .