Preliminary Efficacy Results Research Articles

Experience of seven Spanish centres with echoendoscopically implanted 32P microparticles associated with chemotherapy in locally advanced pancreatic adenocarcinoma.

e16358 Background: 32P brachytherapy delivered by echoendoscopy (EUS) represents an innovative therapy in locally advanced pancreatic cancer (LAPC). The device to implant it is approved in unresectable LAPC in combination with gemcitabine-based chemotherapy. Our aim is to present the preliminary efficacy and safety results of a series that brings together the experience of seven centres in Spain. Methods: After being assessed by a multidisciplinary committee and meeting eligibility criteria (Table 1), patients signed consent to receive intratumoural 32P by EUS within the international observational registry OSPREY (March 2022-February 2024). Complications associated with intratumoural 32P injection via EUS, associated adverse events (AEs) and preliminary efficacy results (progression-free survival [PFS], distant and locoregional, and overall survival [OS]) were analysed. Results: Thirteen patients (7 females; age 65 years [range 48, 79]; 10 ECOG 1) with unresectable LAPC (7 in head, 3 in uncinate and 3 in body; tumour size 36.8 mm [range 25, 60]) were included. The median time from tumour diagnosis to procedure was 5 months [1.4, 28.9]. Only 4 patients (30 %) had received a previous line of treatment. Eleven patients (85%) received gemcitabine-based chemotherapy concomitant with intratumoural 32P (8 gemcitabine plus nabpaclitaxel; 3 gemcitabine monotherapy). There were no complications or AEs related to 32P injection or EUS. A total of 7 patients (54%) had chemotherapy-related AEs, with 2 cases of G3 neutropenia; 6 had G1-2 toxicities: neutropenia (1), thrombopenia (2), anaemia (1), nausea (1), asthenia (1), diarrhoea (1) and constipation (1). Two patients underwent surgery after intratumoural treatment. With a median follow-up of 17.3 months after injection, 8 patients (61.5 %) have progressed, all of them distantly, and three also locoregionally. The median PFS since 32P injection is 8.4 months (95% CI 2.7, NR). Six patients are alive at the end of follow-up (46.2 %) with a median OS since 32P injection of 13.8 months 95% CI [10, NR]. At data cut-off, five patients remain on-treatment. Conclusions: Our initial experience suggests that intratumoural 32P associated with gemcitabine-based chemotherapy is safe. Patients after 32P injection achieve long overall survival. Our ongoing prospective registry will allow evaluation of the oncological outcomes of this therapy at longer follow-up times. [Table: see text]

NETOS: A personalized approach of neoadjuvant therapy, including INCB099280 monotherapy and bladder preservation, for muscle-invasive urothelial bladder carcinoma (MIBC) with ctDNA monitoring.

TPS4624 Background: MIBC is a systemic disease as >40% of patients (pts) ultimately develop recurrence after radical cystectomy (RC). For pts who cannot receive or refuse cisplatin-based chemotherapy there is no standard-of-care neoadjuvant therapy. Single-agent pembrolizumab, given neoadjuvantly in patients with T2-4N0M0 MIBC, was effective in PURE-01 trial. A proportion of these pts refused RC and were cured with pembro and redo transurethral resection of the bladder tumor (reTURBT; Bandini et al. PMID: 32979511). There are increasing concerns by the pts related to the need to undergo RC whenever they achieve a clinical complete response (cCR) with TURBT and systemic therapy. INCB099280 is a potent, orally bioavailable, selective, small molecule that targets PD-L1 that is being developed for the treatment of advanced malignant diseases. A phase 1, dose-escalation and expansion study is ongoing in pts with select advanced solid tumors (NCT04242199); safety and preliminary efficacy results have been reported (Prenen et al. ESMO-IO 2023). Our hypothesis is that INCB099280 can be offered in biomarker-selected pts as a maintenance therapy instead of any additional treatment, provided that a cCR after the induction phase is obtained. Methods: Pts should have a predominant urothelial carcinoma (UC) histology, have a clinical stage T2-T4N0M0 MIBC, be ineligible for or refuse to receive cisplatin-based chemotherapy. The study will also select pts with a circulating tumor DNA (ctDNA)-positive test (Signatera ctDNA assay) and will be staged with pelvic MRI. Pts will receive 12 weeks of INCB099280 at the dose of 400 mg twice daily (BID), continuously. Restaging will be planned with ctDNA, imaging and reTURBT. Pts who will achieve a cCR (i.e., no evidence of residual disease at the histological examination, clearance of ctDNA and the evidence of no residual detectable disease at cross-sectional imaging, evaluated locally) will receive additional INCB099280 400 mg BID for a maintenance period of 12 months. Pts with evidence of high grade or infiltrating residual disease will be discontinued from the study. Those with a Ta/T1-low grade disease will be managed according to physician’s preference: they may be eligible to continue within the study protocol and receive maintenance INCB099280 400 mg BID for a total period of 12 months. The primary endpoint is the proportion of cCR and the study is planned according to A'Hern one-stage binomial design, with H0 ≤5% and H1 ≥20%, 5% one-sided Alpha, 80% power and 10% drop-out rate. The overall sample size Will be of 30 pts. Secondary endpoints will include safety (CTCAE v.5.0), event-free survival, bladder-intact overall survival (OS) and OS (EUCT number: 2024-511029-73-00). Clinical trial information: 2024-511029-73-00.

First-in-human study of HMPL-295, an ERK1/2 inhibitor, in patients with advanced solid tumors: Dose-escalation results of monotherapy.

e15112 Background: HMPL-295 (’295) is an extracellular signal-regulated kinase 1 and 2 (ERK1/2) inhibitor with potent activity in non-clinical studies. This is a first-in-human, dose escalation study of ’295 in patients (pts) with advanced solid tumors. Here, we report the results of the mono dose escalation stage. Methods: Pts with advanced solid tumors who have failed standard therapy were enrolled to receive ’295 once daily (QD) in 28-day cycles or ’295 QD 2 weeks on/1 week off (2w on/1w off) in 21-day cycles. The mTPI-2 design was used for dose escalation, having explored from 5 to 75 mg QD in 6 cohorts, as well as 75 mg and 100 mg QD 2w on/1w off. The study aims to determine the maximum tolerated dose (MTD)/recommended phase 2 dose (RP2D), safety, tolerability, pharmacokinetics/pharmacodynamics (PK/PD), and preliminary efficacy (best of response, BOR). Results: As of Dec 11, 2023, 47 pts with advanced solid tumors were enrolled (n=1, 1, 3, 6, 12, 5, 13, 6 in 5, 10, 20, 40, 50, 75 mg QD cohorts, 75, 100 mg QD 2w on/1w off cohorts, respectively), with a median age of 58 years, 23 (48.9%) male pts. During the dose escalation from 5 to 75 mg QD cohort, 1 pt given 40 mg QD experienced a dose-limiting toxicity (DLT) of grade 3 dermatitis acneiform and 2 pts given 75 mg QD experienced DLTs of grade 3 rash and acute kidney injury (AKI). As for intermittent-administration cohorts, 2 pts given 100 mg QD 2w on/1w off experienced DLTs of grade 3 AKI and rash maculo-papular. After multiple-dose oral administration, ’295 plasma concentrations reach peak at 1.0-2.0 hours post dose and the exposure (Cmax and AUC) displayed dose dependent increase. The accumulation ratio (AUC) was 2.1–3.4 after repeat dosing, reaching steady-state around day 15. ’295 inhibited ribosomal S6 kinase (RSK) phosphorylation which is a downstream signaling molecule regulated by ERK1/2 and stimulated by phorbol 12-myristate 13-acetate (PMA). The BOR was partial response each in 1 pt with duodenal adenocarcinoma in 40 mg QD cohort,1 pt with endometrial cancer in 50 mg QD cohort and 1 pt with non-small cell lung cancer (NSCLC) in 75 mg QD 2w on/1w off cohort. Stable disease with tumor shrinkage was also observed in 2 pts with NSCLC on 50 mg QD and 75 mg QD 2w on/1w off cohort respectively, and 1 pt with pancreatic ductal adenocarcinoma in 100 mg QD 2w on/1w off cohort. 25 (53.2%) pts reported grade ≥3 TEAEs. The most common (≥10.0%) ≥ grade 3 TEAEs were rash (10.6%) and anemia (10.6%). Conclusions: Considering safety, tolerability, PK/PD and preliminary efficacy results, RP2D was determined to be 50 mg QD. Clinical trial information: NCT04908046 .

Preliminary efficacy and safety results from RC48-C017: A phase II study of neoadjuvant treatment with disitamab vedotin plus toripalimab in patients with muscle invasive bladder cancer (MIBC) with HER2 expression.

4568 Background: Disitamab vedotin (DV) is a novel humanized anti-HER2 antibody-drug conjugate. DV plus toripalimab (a recombinant humanized anti-PD-1 monoclonal antibody) showed promising antitumor activity in metastatic urothelial carcinoma (ASCO 2023). This study aimed to evaluate the safety and efficacy of DV plus toripalimab as neoadjuvant therapy in MIBC patients with HER2 expression. Methods: This is a prospective multicenter phase 2 trial which planned to enroll 40 pts. Primary endpoint is pathological CR (pCR) rate; secondary endpoints include pathologic response rate, safety and tolerability. Study enrolled pts who are previously untreated MIBC (cT2-T4aN0-1M0), medically fit for and agree to undergo curative intent RC+PLND. HER2 expression was required to be immunochemistry (IHC) ≥ 1+ tested locally. Pts received DV 2 mg/kg plus toripalimab 3 mg/kg every two weeks for 6 cycles, followed by RC+ PLND within 4 weeks. Here we present preliminary efficacy and safety results. Results: 44 pts were enrolled and clinical stage at diagnosis was: cT2N0 (38.6%), cT3N0 (29.5%), cT4aN0 (13.6%), cT2-4aN1 (18.2%). HER2 expression of IHC 1+, 2+ or 3+ was 11.4%, 56.8%, and 31.8%, respectively. By the data cut-off date (Feb-2024), 29 pts (65.9%) completed RC + PLND. The pCR rate was 62.1% (18/29). The pathologic response rate was 75.9% (22/29). Common treatment-related adverse events (TRAEs) were mostly Grade 1 or 2, including alopecia (36.4%), alanine aminotransferase increased (31.8%), aspartate aminotransferase increased (25.0%), rash (22.7%), gamma-glutamyl transferase increased (22.7%), peripheral sensory neuropathy (22.7%), and asthenia (20.5%). Grade 3-4 TRAEs were reported in 15.9% of pts. No deaths occurred. No surgery was cancelled due to TRAEs. Survival data are not yet mature. Conclusions: Neoadjuvant treatment with DV plus toripalimab showed promising efficacy results and was well tolerated in operable MIBC pts with HER2 expression. These results will support further investigation for DV plus toripalimab in this population. Clinical trial information: NCT05297552 .

The preliminary efficacy and safety results of neoadjuvant phase 2 study of penpulimab combined with taxanes and carboplatin in triple-negative breast cancer (neoTAPPL).

e12617 Background: The KEYNOTE-522 trial demonstrated the addition of pembrolizumab to anthracycline-taxane-platinum chemotherapy improves pathologic complete response (pCR) and event free survival (EFS) in triple-negative breast cancer (TNBC). Penpulimab is a newly developed PD-1 monoclonal antibody with complete elimination of FcgR binding and ADCC/ADCP. This study aims to assess the efficacy of the anthracycline free neoadjuvant regimen of penpulimab plus carboplatin and taxanes in TNBC. Methods: In this open-label, phase 2 study, patients with untreated, histologically confirmed TNBC in stage II-III were enrolled. Patients received 6 cycles of neoadjuvant therapy with penpulimab (200 mg, d1, q3w) plus taxanes (docetaxel 75 mg/m2 or nab-paclitaxel 260 mg/m2, d1, q3w) and carboplatin (AUC=6, d1, q3w). Patients who either completed or discontinued the neoadjuvant treatment would undergo breast surgery. Adjuvant chemotherapy and immunotherapy were at the discretion of the treating physician, and radiation therapy was per standard of care. The primary endpoint was the rate of pCR based on the definition of ypT0/Tis ypN0. Secondary endpoints included residual cancer burden (RCB), EFS, overall survival (OS), adverse events (AE), and immune response biomarkers. Based on the Simon’s Two-Stage design, if >7 of 16 patients achieved pCR, the enrollment would proceed to full accrual of 46 patients as planned. If >23 of 46 patients achieved pCR, we would deem the study to have met the primary endpoint. Results: Nine out of 16 pts achieved pCR in the first stage, reaching the threshold for the second stage. From Nov 2022 to Jan 2024, 22 patients were enrolled, among which 17 patients received neoadjuvant treatment and underwent breast surgery. The median age was 51 years (range, 32-69). 13 (76.5%) patients had stage II breast cancer at diagnosis. 10 of the 17 patients achieved pCR (58.8%; 95% CI, 32.9-81.6), and 12 patients achieved RCB 0-I (70.6%; 95% CI, 44.0%-89.7%). Subgroup analysis showed the pCR rate of patients who were diagnosed initially to be lymph node negative was 75.0% (6/8), higher than that of patients who were lymph node positive (44.4%; 4/9). The ORR and DCR were 82.4% (95% CI, 56.6%-96.2%) and 88.2% (95% CI, 63.6%-98.5%), respectively. Treatment-emergent adverse events (TEAEs) of any grade occurred in all 17 pts, in which 10 (58.8%) were grade ≥3. The most common grade ≥3 TEAEs were neutropenia (47.1%), leukopenia (41.2%), anemia (23.5%), and thrombocytopenia (17.6%). 6 patients (35.3%) experienced immune related adverse events (irAEs), all of which were grade 1 hypothyroidism. Conclusions: The preliminary results demonstrated that penpulimab plus carboplatin and taxanes as neoadjuvant therapy for early-stage TNBC showed promising antitumor efficacy and manageable safety profile. The study is still ongoing. Clinical trial information: ChiCTR2300071925.

Safety and efficacy of IBI343 (anti-claudin18.2 antibody-drug conjugate) in patients with advanced pancreatic ductal adenocarcinoma or biliary tract cancer: Preliminary results from a phase 1 study.

3037 Background: Prognosis for advanced pancreatic ductal adenocarcinoma (PDAC) and biliary tract cancer (BTC) remains poor, with limited treatment options available. Expression of claudin18.2 (CLDN18.2) has emerged as a potential target for anti-cancer treatment. Herein, we report preliminary safety and efficacy results of IBI343, an antibody-drug conjugate (ADC) consisting of anti-CLDN18.2 monoclonal antibody conjugated to exatecan (topoisomerase I inhibitor), in patients (pts) with advanced PDAC or BTC in a phase 1 study. Methods: Eligible pts who failed or were intolerant to standard treatment were enrolled. IBI343 were intravenously administered at 6 mg/kg or 8 mg/kg Q3W. In dose escalation, pts were enrolled regardless of CLDN18.2 expression. In dose expansion, pts were required to have CLDN18.2 expression ≥40% (1+/2+/3+ staining intensity by immunohistochemistry). Primary endpoint was safety. Secondary endpoints included objective response rate (ORR), disease control rate (DCR), duration of response (DoR) and progression free survival (PFS) assessed by investigator per RECIST v1.1. Results: As of December 19, 2023, 35 pts (1 pt in dose escalation and 34 pts in dose expansion) were enrolled from China and Australia (males: 57.1%, median age: 58.0 years, ECOG PS 1: 71.4%, stage IV: 91.4%, median lines of prior treatment: 2) including 28 PDAC pts and 7 BTC pts. Pts received IBI343 at 6 mg/kg (n=17) or 8 mg/kg (n=18). Median duration of treatment was 7.0 weeks (range: 3.0-23.6) with 23 (65.7%) pts still on treatment. In all pts, treatment-related adverse events (TRAEs) occurred in 28 (80.0%) pts including grade ≥3 TRAEs in 9 (25.7%) pts. Common TRAEs (≥20%) were anemia (42.9%), neutrophil count decreased (28.6%), nausea (25.7%), vomiting (25.7%) and white blood cell count decreased (22.9%). Serious TRAEs occurred in 4 (11.4%) pts. TRAEs leading to dose interruption and treatment discontinuation occurred in 7 (20.0%) pts and 1 (2.9%) pt respectively. No TRAE led to death. Safety profiles of IBI343 in PDAC and BTC were comparable with the whole study cohort and no new safety signal was observed. As of January 15, 2024, 25 pts at 6 mg/kg and 8 mg/kg were efficacy evaluable. Partial response (PR) was observed in 7 pts (5 PDAC and 2 BTC). The ORR was 28.0% (95%CI: 12.1-49.4) and DCR was 80.0% (95%CI: 59.3-93.2). In evaluable pts at 6 mg/kg with CLDN18.2 expression ≥60% (1+/2+/3+, n=13), 5 pts had PR with ORR of 38.5% (95%CI: 13.9-68.4) and DCR of 84.6% (95%CI: 54.6-98.1). Among 10 PDAC pts in this subgroup, ORR was 40% (95%CI: 12.2-73.8). DoR and PFS data were immature. More updated data on safety and efficacy will be presented at the meeting. Conclusions: IBI343 was well tolerated with favorable safety profiles and encouraging efficacy in CLDN18.2-positive PDAC and BTC. Clinical trial information: NCT05458219 .

Safety and preliminary efficacy results of IBI389, an anti-CLDN18.2/CD3 bispecific antibody, in patients with solid tumors and gastric or gastro-esophageal tumors: A phase 1 dose escalation and expansion study.

2519 Background: CLDN18.2 expression has been observed in various solid tumors especially in gastric cancer, indicating its potential as a novel target for anti-tumor therapy. IBI389 is an anti-CLDN18.2/CD3 bispecific antibody that induces immune synapse formations by linking CD3 molecules in T-cell receptor complexes and CLDN18.2 antigens on the membrane of tumor cells. Herein, we report preliminary results from a phase I study to evaluate safety and efficacy of IBI389 in patients (pts) with advanced solid tumors. Methods: Eligible pts with advanced solid tumors who failed or were intolerant to standard treatments were enrolled. The dose escalation of IBI389 monotherapy used intra-patient dose escalation with accelerated titration and the classic 3+3 design (0.003 µg/kg to 600 µg/kg). Selected dose levels were expanded in pts with advanced gastric/gastroesophageal junction cancer (G/GEJ C) and pancreatic ductal adenocarcinoma (PDAC). The primary objective was safety. Secondary objective was efficacy assessed by investigator per RECIST v1.1 including objective response rate (ORR) and disease control rate (DCR). Results: As of January 9, 2024, a total of 114 pts were enrolled (males: 67.5%, median age: 60.0 years, G/GEJ C: 32.5%, PDAC: 57.9%, stage IV: 81.6%). No dose-limiting toxicity (DLT) was observed during dose escalation. The MTD was not reached. In all pts, treatment-emergent adverse events (TEAEs) occurred in 112 (98.2%) pts including 76 (66.7%) pts with grade ≥3 TEAEs. Treatment-related adverse events (TRAEs) occurred in 111 (97.4%) pts including 63 (55.3%) pts with grade ≥3 TRAEs. The most common grade ≥3 TRAEs (≥ 4%) were gamma-glutamyl transferase increased (21.9%), lymphocyte count decreased (13.2%) and nausea (4.4%). Cytokine release syndrome (CRS) related adverse events occurred in 65 (57.0%) pts including 1 (0.9%) pts with grade 3 CRS and no grade 4 or 5 CRS. TEAEs leading to dose interruption and treatment discontinuation occurred in 44 (38.6%) and 8 (7.0%) pts. Preliminary efficacy of IBI389 was observed in pts with CLDN18.2 expression ≥10% (immunohistochemistry 2+/3+). In G/GEJ C pts with previous treatments ≥2 lines receiving IBI389 at various dose levels ranging from 10µg/kg to 600 µg/kg (n=26), 8 pts had partial response (PR) and 11 pts had stable disease (SD). The ORR was 30.8% (95%CI: 14.3-51.8) and DCR was 73.1% (95%CI: 52.2-88.4). Conclusions: IBI389 showed manageable safety profiles in pts with advanced solid tumors and preliminary efficacy in CLDN18.2-positive pts with G/GEJ C. Clinical trial information: NCT05164458 .

Abstract PO1-29-02: Two and a half years follow-up data of HER2-targeted bispecific antibody KN026 combined with docetaxel as first-line treatment for HER2-positive recurrent/metastatic breast cancer

Abstract Background: KN026 is a novel bispecific HER2-targeted antibody. Fully humanized, IgG1-like antibody binds to two distinct HER2 epitopes, the same domains as trastuzumab and pertuzumab. Preliminary safety and efficacy results (data as of Aug 18, 2022) were presented at SABCs 2022(PD18-08), showed promising efficacy and tolerability. Herein, we update the 2.5-year follow-up results. Methods: Eligible subjects with recurrent/metastatic breast cancer, HER-2 positive and treatment-naive were enrolled. Subjects received KN026 30 mg/kg combined with docetaxel 75 mg/m2 Q3W until disease progression, unacceptable toxicity, or other reasons. The primary endpoints were ORR and DoR. The secondary endpoints included safety, PFS and OS. Results: As of data cut-off date (Sep 15, 2023), 57 subjects were enrolled, the median age was 52 years (min:30, max:67), 100% were female, and 91.2 % (52/57) were stage IV. There were 34 and 23 subjects with and without visceral metastasis, respectively. 48 subjects with high HER2 expression (IHC 3+), and the other 9 subjects with HER2 expression 2+ or 1+. The confirmed ORR within 55 evaluable subjects was 76.4% (42/55). The DoR was not reached yet with a median follow-up of 27.0 mons (95% CI: 26.28, 28.98). The median study follow-up was 30.6 mons (95% CI: 29.11, 31.77). The mPFS was 27.7 mons (95% CI:17.97, NE) and the mOS was not reached. The OS rates at 12m, 24m and 30m were 93.0% (95% CI: 82.37, 97.31), 84.2% (95% CI: 71.85, 91.45) and 78.5% (95% CI: 65.25, 87.21). The mPFS of subjects with or without visceral metastasis were 23.6 mons and not reached. The mPFS of subjects with or without brain metastasis were 13.7 mons and 28.1 mons, respectively. The mPFS of 48 subjects with high HER2 expression (3+) was 28.1 months. The incidence of KN026-related Grade≥3 TRAE was 43.9% (25/57), including neutrophil count decreased 24.6% (14/57), white blood cell count decreased 12.3% (7/57), hypokalaemia 7.0% (4/57), diarrhoea 3.5% (2/57) and others less than 2%. The incidence of serious adverse events related to KN026 was 12.3% (7/57). There was no KN026 -related death. Conclusions: KN026 in combination with docetaxel is well tolerated and has shown promising clinical benefit as 1L treatment for HER2-positive BC. After 2.5 years follow-up, mPFS was 27.7 mons and the 24-months OS rate was 84.2%, which is very promising. No new safety signals were observed. Robustness of efficacy and safety results will be further confirmed in an ongoing randomized phase 3 clinical trial with PTH as control. Citation Format: Qingyuan Zhang, Jingxuan Wang, Quchang Ouyang, Xiaojia Wang, Jingfen Wang, Lu Gan, Daren Lin, Zhong Ouyang, Ting Xu, Yilan Liu, Yuan Lv. Two and a half years follow-up data of HER2-targeted bispecific antibody KN026 combined with docetaxel as first-line treatment for HER2-positive recurrent/metastatic breast cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO1-29-02.

Abstract CT038: Preliminary efficacy and safety results of anti-TROP2 ADC SKB264 (MK-2870) in patients (pts) with previously treated advanced gastric (G) or gastroesophageal junction (GEJ) cancer from a Phase 2 study

Abstract Background: Overexpression of TROP2 (trophoblast cell surface antigen 2) in advanced gastric cancer is known as a poor prognostic factor. SKB264 (MK-2870) is a TROP2 ADC developed with a novel linker to conjugate the payload, a belotecan-derivative topoisomerase I inhibitor. The linker is affected by both extracellular pH-sensitive cleavage and intracellular enzymatic cleavage within tumor cells, which leads to efficiently release payload inside tumor cells as well as within tumor microenvironment to exert its anti-tumor effects. Here, we report the preliminary results from a Phase 2 expansion cohort in pts with advanced G/GEJ cancer. Methods: Pts with previously treated inoperable advanced G/GEJ adenocarcinoma were enrolled to receive SKB264 monotherapy at 5 mg/kg Q2W until disease progression or unacceptable toxicity in Phase 2 expansion cohort of KL264-01 study (NCT04152499). Pts with heavily pre-treated G/GEJ cancer were enrolled first, and then the cohort was amended to enroll pts with only one prior therapy of chemotherapy and anti-PD-1/L1 therapy. Tumor assessment was performed every 8 weeks per RECIST v1.1 assessed by investigator. Results: At data cutoff date (Nov 22, 2023), a total of 48 pts were enrolled and followed up for at least 9 weeks. 24 pts (50.0%) had received one prior line of therapy (2L), while 24 pts (50.0%) had received ≥ 2 prior lines of therapy (3L+). 40 pts (83.3%) had received prior anti-PD-1/L1 inhibitors. Treatment-related adverse events (TRAEs) of ≥ Grade 3 were reported in 52.1% of pts. The most common ≥ Grade 3 TRAEs (occurred in ≥5% of pts) were anemia (20.8%), neutrophil count decreased (18.8%), WBC decreased (12.5%) and neutropenia (6.3%). TRAEs leading to dose reduction and dose delay occurred in 18.8% and 33.3% of pts, respectively. No TRAEs leading to treatment discontinuation or deaths occurred. No neuropathy or drug-related ILD/pneumonitis was reported. Of 41 response-evaluable pts (defined as ≥ 1 on-study scans), the ORR was 22.0% (9 PRs, 2 pending confirmation) and disease control rate (DCR) was 80.5%. The ORRs in the 2L and 3L+ setting were 27.3% (including 2 pending confirmation) and 15.8%, respectively. Median duration of response (DoR) was 7.5 months (mos). In the subset of 3L+ pts (n=24 including 54.2% of pts with ≥ 4 prior lines of therapy) with more mature follow-up (median follow up of 14.6 mos), median progression free survival (mPFS) was 3.7 mos (95% Cl: 2.6, 5.4); median overall survival (mOS) was 7.6 mos (95% Cl: 5.3, 15.5) with 12-mo OS rate of 32.6%. Conclusions: The preliminary data suggests that pts with heavily pre-treated advanced G/GEJ cancer could achieve durable response and potentially prolonged OS from SKB264 monotherapy, with a manageable safety profile. A Phase 3 global study of SKB264 monotherapy vs SOC in 3L+ G/GEJ adenocarcinoma is being planned. Citation Format: Jordi Rodon, Zev A. Wainberg, Mingjun Zhang, Tianshu Liu, Bo Liu, Guohua Yu, Yongmei Yin, Shuang Zhang, Yanjun Mi, Xingya Li, Xian Wang, Yunpeng Liu, Xiang Wang, Ying Cheng, Xiaoqing Zhang, Yalan Yang, Junyou Ge, Omobolaji O. Akala, Elliot Chartash, Jin Li. Preliminary efficacy and safety results of anti-TROP2 ADC SKB264 (MK-2870) in patients (pts) with previously treated advanced gastric (G) or gastroesophageal junction (GEJ) cancer from a Phase 2 study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT038.

Abstract CT227: Anti-LAG-3 antibody LBL-007 in combination with anti-PD-1 antibody toripalimab, in patients with advanced malignant tumors: A phase Ib/II, open-label, multicenter, dose escalation/expansion study

Abstract Background: Dual inhibition of PD-1 and LAG-3 may have the potential to increase the immune response against tumor growth synergistically. Here we report the preliminary safety and efficacy results of LBL-007 (an anti-LAG-3 antibody) in combination with toripalimab (an anti-PD-1 antibody) in patients with advanced malignant tumors. Methods: Patients with advanced malignant tumors, including but not limited to nasopharyngeal carcinoma (NPC), non-small cell lung cancer (NSCLC), esophageal squamous cell carcinoma (ESCC), and head and neck squamous carcinoma (HNSCC), with or without prior anti-PD-(L)1 therapy, were enrolled. This trial was divided into two parts: phase Ib (dose escalation study), patients received LBL-007 at 200 mg or 400 mg plus toripalimab at 240 mg (both administered i.v. Q3W), and phase II (dose expansion), patients received LBL-007 at 400 mg and toripalimab at 240 mg (both administered i.v. Q3W). The primary objective was to assess safety and tolerability; the secondary objectives were to assess pharmacokinetics, pharmacodynamics, and preliminary efficacy (per RECIST 1.1). Results: By December 1, 2023, 80 patients were enrolled in phase Ib (10 patients) and phase II (70 patients). Of these, 30 (37.5%) were NPC patients, and 50 (62.5%) had other tumors. The median follow-up was 18.1 months (95% CI: 11.1, NE). No DLTs were observed in phase Ib. Seventy-three patients out of 80 (91.3%) experienced TEAEs of all grades, with 19 (23.8%) having grade ≥3 TEAEs. The most common any grade TEAEs (≥15%) were anaemia (40.0%), hypoalbuminaemia (18.8%), weight decreased (18.8%), hyponatremia (17.5%), proteinuria (17.5%), asthenia (17.5%), lymphocyte count decreased (16.3%), aspartate aminotransferase increased (16.3%), hypertriglyceridaemia (15.0%), and rash (15.0%). Treatment interruption and permanent discontinuation due to TEAEs occurred in 6 (7.5%) patients each. Sixteen patients (20.0%) experienced SAEs. Four patients experienced TEAEs leading to death, all events are related to underlying disease or disease progression, none of which were related to LBL-007 or toripalimab. Out of 75 efficacy evaluable patients, ORR and DCR were 13.3% (10/75) and 48.0% (36/75), respectively. In 29 efficacy evaluable NPC patients, ORR and DCR were 20.7% (6/29), and 62.1% (18/29), respectively. Among the group of 12 anti-PD-(L)1 treatment-naïve NPC patients and 17 anti-PD-(L)1 treated NPC patients, the ORR were 33.3% (4/12) and 11.8% (2/17), DCR were 75.0% (9/12) and 52.9% (9/17), respectively; Of note, the mPFS was up to 11.9 months (95%CI: 1.3, not reached) in anti-PD-(L)1 treatment-naïve NPC patients. Conclusions: LBL-007 in combination with toripalimab is well tolerated in patients with advanced malignant tumors and has demonstrated encouraging preliminary efficacy in patients with advanced NPC with or without prior anti-PD-(L)1 therapy. Clinical trial information: NCT05102006. Citation Format: Yunpeng Yang, Yuanyuan Zhao, Wenfeng Fang, Yan Huang, Yaxiong Zhang, Yi Ba, Zhen Wang, Chao Deng, Desheng Hu, Wei Wang, Guiling Li, Suxia Luo, Zhichao Fu, Haisheng Zhu, Huili Wang, Shiwei Zhao, Tao Li, Charles Cai, Li Zhang. Anti-LAG-3 antibody LBL-007 in combination with anti-PD-1 antibody toripalimab, in patients with advanced malignant tumors: A phase Ib/II, open-label, multicenter, dose escalation/expansion study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT227.

Abstract CT021: Preliminary clinical results of a therapeutic cancer vaccine PDC*lung01 in combination with anti-PD-1 in patients (pts) with stage IV NSCLC

Abstract Background PDC*lung01 (IMP) is a therapeutic cancer vaccine based on an irradiated plasmacytoid dendritic cell line loaded with HLA-A*02:01-restricted peptides (NY-ESO-1, MAGE-A3, MAGE-A4, Multi-MAGE-A, MUC1, Survivin and Melan-A), able to prime and expand peptide-specific CD8+ T cells in vitro and in vivo, and is synergistic with anti-PD-1. Methods In this phase I/II study, HLA-A*02 positive NSCLC pts were enrolled in 4 cohorts: resected stage II/IIIA in adjuvant setting treated with low dose (A1) or high dose (A2) of IMP following SOC; or untreated stage IV NSCLC with measurable disease, PD-L1≥50% and no targetable driver mutation, treated with low dose (B1) or high dose (B2) of IMP in combination to pembrolizumab 200mg q3w, continuously. IMP was simultaneously administered by SC and IV route weekly for 6 consecutive doses. Objective response rate (ORR) and progression-free survival (PFS) were assessed in cohort B2. We report herein preliminary efficacy results of the first 21 pts analysed when the 19th evaluable patient reached the 9-months PFS and the safety of 38 pts. Results Out of 21, 19 pts receiving at least 5 doses of IMP and having 1 post-baseline radiological evaluation were evaluated. The median follow-up was 12.5 months. The best objective response (BOR) included 12 PR (63.2%) and 7 SD (36.8%) with ORR of 63.2% (80% CI 45.9% - 78.2%) and a disease control rate (DCR) of 94.7%. The 9mPFS according to the Kaplan-Meier estimate was 52.1% (80% CI 36.5% - 65.56%). The mPFS was 10.9 months. The median duration of response was 9.49 months. An antigen-specific CD8+ T-cell response was induced against the lung antigens of the IMP in 68.4% of pts. Immune responses with remarkable expanded anti-tumor CD8+ T-cells were observed both in PR and SD. More immune response results will be available in the final analysis of the 45 pts of cohort B2. Treatment-related AEs (TRAEs) were mostly Grade 1-2. Only 1 severe TRAE occurred, a Grade 4 allergic infusion-related reaction, leading to IMP discontinuation. Thirteen pts experienced a serious AE, of which 3 were considered causally related to the IMP. Conclusions The BOR, ORR, DCR, PFS, duration of response and safety of PDC*lung01 in combination with anti-PD-1 showed encouraging signals suggesting that this combination may provide a clinical meaningful tumour response in stage IV NSCLC population with a mild safety profile. Interestingly, the immune response observed confirms the mechanism of action of the IMP in relation to clinical activity. Citation Format: Willemijn Theelen, Maurice Perol, Kristof Cuppens, Ingel Demedts, Frank Borm, Bonne Biesma, Els Wauters, Benoit Colinet, Eva-Lotte Buchmeier, Friederike Althoff, Elvire Pons-Tostivint, Charlotte Van de Kerkhove, Denis Moro-Sibilot, Anne Sibille, Sofie Derijcke, Marcin Skrzypski, Joel Plumas, Beatrice De Vos, Channa Debruyne, Frederique Cantero, Stefanie Adriaenssens, Florence Renard, Johan Vansteenkiste. Preliminary clinical results of a therapeutic cancer vaccine PDC*lung01 in combination with anti-PD-1 in patients (pts) with stage IV NSCLC [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT021.

Retrospective Multicenter Cohort Study on Safety and Electroencephalographic Response to Lacosamide for Neonatal Seizures

BackgroundThere is growing evidence supporting the safety and effectiveness of lacosamide in older children. However, minimal data are available for neonates. We aimed to determine the incidence of adverse events associated with lacosamide use and explore the electroencephalographic seizure response to lacosamide in neonates. MethodsA retrospective cohort study was conducted using data from seven pediatric hospitals from January 2009 to February 2020. For safety outcomes, neonates were followed for ≤30 days from index date. Electroencephalographic response of lacosamide was evaluated based on electroencephalographic reports for ≤3 days. ResultsAmong 47 neonates, 98% received the first lacosamide dose in the intensive care units. During the median follow-up of 12 days, 19% of neonates died, and the crude incidence rate per 1000 patient-days (95% confidence interval) of the adverse events by diagnostic categories ranged from 2.8 (0.3, 10.2) for blood or lymphatic system disorders and nervous system disorders to 10.5 (4.2, 21.6) for cardiac disorders. Electroencephalographic seizures were observed in 31 of 34 patients with available electroencephalographic data on the index date. There was seizure improvement in 29% of neonates on day 1 and also in 29% of neonates on day 2. On day 3, there was no change in 50% of neonates and unknown change in 50% of neonates. ConclusionsThe results are reassuring regarding the safety of lacosamide in neonates. Although some neonates had fewer seizures after lacosamide administration, the lack of a comparator arm and reliance on qualitative statements in electroencephalographic reports limit the preliminary efficacy results.

DON in pediatric cerebral malaria, a phase I/IIA dose-escalation safety study: study protocol for a clinical trial

BackgroundDespite treatment with highly effective antimalarial drugs, malaria annually claims the lives of over half a million children under 5-years of age in sub-Saharan Africa. Cerebral malaria (CM), defined as Plasmodium falciparum infection with coma, is the severe malaria syndrome with the highest mortality. Studies in the CM mouse model suggest that a T cell-mediated response underlies CM pathology, opening a new target for therapy in humans. This trial aims to establish the preliminary safety of one such novel therapy, the glutamine antagonist 6-diazo-5-oxo-L-norleucine (DON).MethodsIn this phase I/IIa dose-escalation clinical trial, a single dose of intravenous (IV) DON is administered to three participants groups—healthy adults and adults with uncomplicated malaria, then pediatric participants with CM—to primarily assess safety. The secondary objective of this trial is to assess pharmacokinetics of DON over a range of doses. The open-label adult portion of the trial enrolls 40 healthy adults concurrently with 40 adults with uncomplicated malaria. Cohorts of 10 participants receive a single IV dose of DON with doses escalating between cohorts from 0.1 mg/kg, 1.0 mg/kg, 5.0 mg/kg, to 10 mg/kg. Following subsequent safety review, a randomized, double-blind, and placebo-controlled pediatric study enrolls 72 participants aged 6 months to 14 years with CM. The pediatric portion of the study minimally spans three malaria seasons including a planned interim analysis after 50% of pediatric enrollments. The first half of pediatric participants receive DON 0.1 mg/kg, 1.0 mg/kg, or placebo. Dosing for the second half of pediatric participants is informed by the safety and preliminary efficacy results of those previously enrolled. The pediatric portion of the study has an exploratory outcome evaluating the preliminary efficacy of DON. Efficacy is assessed by diagnostics predictive of CM outcome: electroencephalography (EEG), magnetic resonance imaging (MRI), and transcranial doppler (TCD), measured before and after DON administration. All participants with malaria receive standard of care antimalarials in accordance with local guidelines, regardless of study drug dose group.DiscussionThis preliminary safety and efficacy study evaluates DON, a candidate adjunctive therapy for pediatric CM. If results support DON preliminary safety and efficacy, follow-up phase II and III clinical trials will be indicated.Trial registrationThis trial was registered on ClinicalTrials.gov on 28 July 2022 (NCT05478720).

Preliminary activity and safety results of KRAS G12C inhibitor glecirasib (JAB-21822) in patients with pancreatic cancer and other solid tumors.

604 Background: KRAS G12C mutation is an oncogenic driver and a validated therapeutic target in solid tumors. Glecirasib, a highly selective, covalent oral KRAS G12C inhibitor, has demonstrated promising clinical activity in NSCLC and CRC; however, the efficacy and safety of glecirasib are unknown in PDAC and other solid tumors with KRAS G12C mutation. Methods: Two phase 1/2 trials (NCT05009329 in China; NCT05002270 in US, Europe and Israel) are evaluating the safety and efficacy of glecirasib in patients (pts) with solid tumor harboring KRAS G12C mutations. As both trials have similar inclusion and exclusion criteria, we have pooled the data from them to assess the effect of glecirasib monotherapy in various types of solid tumor with low incidence of KRAS G12C mutation. Here we report the preliminary efficacy and safety results of glecirasib in pts with PDAC and other solid tumors (excluding NSCLC and CRC) from the pooled population of both trials. Results: As of Sep 8, 2023, a total of 48 pts have received glecirasib monotherapy (41 from NCT05009329 and 7 from NCT05002270) and 47 were evaluable for efficacy. This includes 28 PDAC and 19 other solid tumors (7 biliary tract, 3 gastric, 3 small bowel, 1 appendiceal, 1 hepatocellular, 1 peritoneal, 1 posterior bronchial mediastinal, 1 ameloblastic carcinoma and 1 cervical). At baseline, pts had previously received a median of one line of systemic therapy (range: 0 to 4; with 23 pts have received one prior line); 85% Asian, 15% Caucasian; most (45 pts) at 800 mg QD. Among 28 pts with PDAC, 13 achieved confirmed partial response (PR) with the confirmed objective response rate (ORR) of 46.4% (13/28) and disease control rate (DCR) of 96.4%; the median duration of response (DOR) and progression-free survival (PFS) were 4.1 months and 5.5 months (95%CI 1.2, 13.1), respectively. Among 19 pts with other tumor types, the confirmed ORR of 52.6% (10/19) and DCR of 84.2% (16/19) were observed; the median DOR and PFS were 8.3 months and 7.0 months (95% CI 1.1 to 15.2), respectively. Treatment-related AE (TRAE) of any grade occurred in 89.6% (43/48) pts; the most common (≥10%) TRAE were anemia (52.1%), blood bilirubin increased (39.6%), white blood cell count decreased (18.8%), AST increased (18.8%), diarrhea (16.7%), ALT increased (14.6%), asthenia (14.6%), hypertriglyceridemia (10.4%), and nausea (10.4%); ≥Grade 3 TRAE occurred in 25% (12/48) pts; no TRAE were fatal or led to treatment discontinuation. Conclusions: Glecirasib monotherapy is well tolerated and has a manageable safety profile and exhibits promising anti-tumor activity in pts with KRAS G12C mutated PDAC and other solid tumors. Further clinical development of glecirasib in above mentioned population is ongoing (NCT06008288). Clinical trial information: NCT05009329 and NCT05002270 .

The Role of IL-23 Inhibitors in Crohn's Disease.

Promoting a Th17 pathogenic response, the interleukin (IL)-23 pathway is crucial in the pathophysiology of inflammatory bowel disease (IBD). With a favorable safety profile, ustekinumab, a monoclonal antibody targeting the shared p40 component of IL-12/23, is currently approved for the treatment of IBD in patients with disease refractory to corticosteroids and biologic drugs. Risankizumab, mirikizumab, and guselkumab are specific IL-23p19 antagonists tested for the treatment of Crohn's disease (CD). However, only risankizumab currently has been approved for its treatment. Trials with guselkumab and mirikizumab are currently ongoing, with promising preliminary efficacy and safety results. In this review, we provide a summary of the current knowledge about selective IL-23 inhibitors, focusing on their positioning in the therapeutic algorithm of patients with moderate to severe CD.

Abstract B041: A phase 1 study of DS-8201a in combination with olaparib in HER2-expressing malignancies (CTEP #10355): Results of module 1 dose escalation

Abstract Background: DS-8201a is a HER2-targeting antibody drug conjugate with a topoisomerase 1 (top1) inhibitor payload. Preclinical evidence suggests that inhibiting PARP can potentiate top1 inhibitor-induced DNA damage and cytotoxicity. However, the clinical activity of combined top1-inhibiting chemotherapy and PARP inhibition has been limited by toxicity. We hypothesized that targeted delivery of a top1 inhibitor via DS-8201a may reduce systemic toxicity while maintaining synergistic cytotoxic activity in combination with olaparib. This combination is being investigated in the ongoing phase 1 trial CTEP #10355 (NCT04585958) in patients (pts) with advanced solid tumors expressing HER2. We present the safety analysis of pts enrolled to Module 1 (Mod 1) of dose escalation (continuous olaparib). Preliminary efficacy results are explored. Methods: Accrual was limited to pts ≥18 years old with advanced or recurrent solid tumors expressing HER2, defined as HER2 IHC ≥1+ (local testing allowed) or amplification of ERBB2 by NGS or ISH. In Mod 1, pts received DS-8201a IV once every 3 weeks and olaparib twice daily (BID) continuously in a 3+3 dose escalation design. Dose Level 1 (DL1) of Mod 1 evaluated DS-8201a dosed at 4.4mg/kg with olaparib 100mg BID Days 1-21. Dose Level 2 (DL2) of Mod 1 evaluated DS-8201a dosed at 5.4mg/kg with olaparib 100mg BID Days 1-21. The primary objective was to evaluate the safety and tolerability of combined DS-8201a + olaparib as graded by CTCAE v5. Secondary objectives include assessment of clinical activity as measured by objective response rate (ORR), clinical benefit rate (CBR; partial response [PR] + complete response [CR] + stable disease [SD] ≥6 months [mo]), median progression-free survival (PFS), and duration of response (DOR). Results: As of 30-Nov-2022, 10 pts were treated in Mod 1, with median age of 62.5 years. 10% were Asian, 10% were African American, and 80% were white. 40% had endometrial cancer and 60% had ovarian cancer. 6 of 7 pts treated on DL1 were DLT-evaluable, of which 1 patient experienced a DLT of Grade (G) 4 neutropenia. All 3 pts in DL2 were DLT-evaluable, and each experienced a DLT (2 pts with G4 febrile neutropenia, 1 pt with G4 neutropenia). Most common TRAEs in Mod 1 included: ANC decrease (60% G4, 20% G3, 20% G1/2), platelet count decrease (20% G4, 20% G3, 40% G1/2), and anemia (70% G3, 20% G1/2). All Mod 1 pts required dose holds, dose reductions, and/or discontinuation of olaparib. Of the 10 pts in Mod 1, 40% achieved a RECIST response (1 CR, 3 PR). 40% had SD lasting ≥6 mo, for a CBR of 80%. Median PFS is estimated at 7.4 mo (95% CI 4.7mo-not reached), with 7 patients alive and progression-free at 6 mo. Conclusion: Continuous dosing of olaparib in combination with DS-8201a yielded an unacceptable safety profile and dose escalation in Mod 1 was not continued. An alternative dosing schedule was initiated in Module 2 (Mod 2) evaluating DS-8201a IV every 3 weeks and olaparib BID Days 8-14; accrual to Mod 2 is ongoing. There is preliminary evidence of clinical activity of this combination. Citation Format: Elizabeth K. Lee, Andrea E. Wahner Hendrickson, Gerardo Colon-Otero, Cheryl A. Pickett, Niya Xiong, Su-Chun Cheng, Madeline Polak, Hannah Sawyer, Martin Hayes, Ursula A. Matulonis, Geoffrey I. Shapiro, Panagiotis A. Konstantinopoulos. A phase 1 study of DS-8201a in combination with olaparib in HER2-expressing malignancies (CTEP #10355): Results of module 1 dose escalation [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr B041.

Selinexor Combined Bortezomib, Lenalidomide, and Dexamethasone for Newly Diagnosed Multiple Myeloma with Extramedullary Disease(EMD) or High-Risk Cytogenetics

BACKGROUND: High-risk(HR) cytogenetics are significantly enriched in MM with EMD , and studies consistently showed EMD and HR cytogenetics were associated with poor outcome. To date, there is no established approach for treatment of newly diagnosed multiple myeloma (NDMM) with EMD. Selinexor is a first-in-class Selective Inhibitor of Nuclear Export (SINE) compound that selectively binds and inactivates XPO1, which leads to accumulation of tumor suppressor proteins in the nucleus and re-activation of cell cycle regulators such as p53, FOXO, IkB. Meanwhile, by forcing the nuclear retention of the eIF4E protein, Selinexor reduces the cytoplasmic ribosomal translation of oncoproteins, including c-Myc, Bcl-2 and Bcl-6. In the STORM study(NCT02343042), 122 patients(pts) with penta-exposed, triple-class refractory multiple myeloma were enrolled to receive Selinexor combined with low-dose dexamethasone. 27 patients were diagnosed with EMD at baseline. The median age of patients was 64 years, the median prior therapies were 7, and 8 pts had high risk cytogenetics. Follow-up evaluation of plasma cell tumor was performed in 16 cases, and complete disappearance or shrinkage of extramedullary lesions was observed in 9 cases. It indicates that Selinexor has clinical activity in the treatment of plasma cell tumor or EMD. The treatment of MM with EMD or HR cytogenetics still faces great challenges, because there is no uniform guideline and consensus to recommend standard protocols, and prospective clinical studies are urgently needed to explore new treatment strategies. METHODS: Eligible pts were aged≥18 years of NDMM with EMD or HR cytogenetics, and an Eastern Cooperative Oncology Group(ECOG) performance status of 0-2. For induction/consolidation(21-day cycles), pts received 8 cycles of SVRd (Selinexor 60 mg PO weekly, Bortezomib 1.3 mg/m2 SC days1, 4, 8, 11, Lenalidomide 25 mg PO days 1-14, and Dexamethasone 40 mg PO weekly. In maintenance (28-day cycles), pts received SR (Selinexor+ Lenalidomide) at least 2 years until disease progression, death or withdrawal. The primary endpoint was overall response rates (ORR) by end of induction. The secondary endpoints are complete response (CR), duration of response (DOR), progression free survival (PFS), overall survival (OS) and toxicity. This trial is registered with Chinese Clinical Trial Registry, number ChiCTR2200062860. RESULTS: 8 pts with previously untreated NDMM were included from August 2022 to July 2023 in 3 hospitals. Median age was 62 (range 55-81). R-ISS stage 3 was present in 2 (25%) pts(Table 1). Based on inclusion criteria, 7 pts had EMD and 1 patient had HR cytogenetic, including 17p deletion (n=2, 25%), 1q21 gain(n=2, 25%). According to IMWG criteria, the ORR of 8 pts with NDMM was 100%, including 2 stringent complete response(sCR), 3 CR, 2 very good partial response (VGPR) and 1 partial response (PR). 1 patient evaluated with sCR at the end of the induction period was evaluated with MRD negativity after autologous stem cell transplantation (ASCT). Median time to first response in patients with a partial response or better was 1 months (1-2). This result established that SVRd regimen has a prospective response for MM with EMD or HR cytogenetic. The most common grade 3-4 treatment-emergent adverse events (occurring in ≥10% of pts) were thrombocytopenia. The most common treatment-related adverse events were grade 1 or 2, including nausea (25%), fatigue (25%), and anorexia (25%). Overall, the severe toxicities are manageable. CONCLUSIONS: SVRd as induction prior ASCT is safe and allows deep responses in NDMM patients with EMD or HR cytogenetic profile. It is worthy of further study based on the preliminary efficacy results. Longer-term results still require more pts have been enrolled and further follow-up.

Idarubicin Plus Azacitidine + Venetoclax As Induction Therapy Achieved High Remission in Elderly Fit- Acute Myeloid Leukemia Patients: Preliminary Results of a Phase II Study

Background The diagnosed age of de novo acute myeloid leukemia (AML) increased over the years, with a median current age of 68 years old. Elderly AML patients characterized by harboring high-risk mutations and significant comorbidities, usually display resistance to conventional chemotherapy, leading to poor outcomes. Although encouraging results from VIALE-A were reported in these years, over 30% participants had limited responses to the regimen of azacitidine + venetoclax after first-cycle induction. Thus, the selection of initial regimen for elderly AML is worth further exploration, especially for those with good fitness (the fitness was evaluated based on the physical ability, emotional status, cognitive function, and comorbidities). Here, we added idarubicin to azacitidine + venetoclax as the induction regimen (IAV regimen) for elderly fit-AML, and reported the preliminary results of efficacy and safety. Methods This single-center, single-arm, phase II trial (ChiCTR2300070190) was conducted at Ruijin Hospital Affiliated to Shanghai Jiao Tong University School of Medicine (Shanghai, China). Elderly patients (aged 60-75 years) of newly diagnosed acute myeloid leukemia (AML) were assessed via modified comprehensive geriatric assessment (mCGA) for the fitness. From April 2023, 22 patients have been enrolled for the treatment of IAV regimen (cycle 1: IDA 6 mg/m 2 d1-3, AZA 75 mg/m 2 d1-7, VEN 100 mg d1, 200 mg d2, 400 mg d3-14; cycle 2: IDA 6 mg/m 2 d1-2, AZA 75 mg/m 2 d1-5, VEN 400 mg d1-14). Among them, 19 patients and 13 patients who have completed cycle 1 and cycle 2 treatment, respectively, were available for analyzing the preliminary efficacy and safety in the trial. The primary objective of this study was to access the composite complete remission (cCR: CR + CRi) rate of IAV treatment. The secondary objective was to evaluate the MRD-negative rate, regimen-related toxicity, and safety. The duration of CR, overall survival rate and event-free survival rate would also be further accessed with sufficient follow-up time. Results The median age of currently enrolled patients was 64 (61-69) years old, and males accounted for 68.4%. Detailed baseline characters were summarized in Table 1. Composite complete remission rate after 1-cycle IAV treatment was achieved in 89.5% (17/19) participants, among which 52.9% (9/17) got MRD-negative status. One patient (1/19, 5.26%) got partial remission, with 7.5% blasts remained. After cycle 2 treatment, the CR rate increased to 92.9% (13/14), and 92.3% (12/13) CR participants were MRD-negative (Table 1). Till now, only 1 patient with chromothripsis-associated rearrangements showed no response and died on day 40 after treatment initiation. The median recovery time of neutrophils (ANC > 0.5×10 9/L) and platelet (PLT > 50×10 9/L) was 20.5 (16-30) days and 20.5 (15-43) days, respectively (Table 1). The most frequent grade 3/4 non-hematological adverse events (according to CTCAE version 5.0) were febrile neutropenia (grade 3, n = 14; grade 4, n = 5), pneumonia (grade 3, n = 5) and sepsis (grade 3, n = 2; grade 4, n = 1) (Table 2). Conclusion In this study, IAV regimen showed promising efficacy on elderly fit-AML patients, with high rates of MRD-negative remission. Non-hematological toxicities were tolerable under current observation. Based on the invigorating preliminary results, the efficacy and potential benefit of IAV regimen on elderly fit AML is worthy of follow-up in the future.

Human Pro-T-Cell Manufacturing in Vitro Is a Safe Procedure for Hematopoietic Stem Cell Transplantation with Delayed T-Cell Reconstitution: Interim Results from 2 Different Clinical Trials

Introduction: Alternative donor Hematopoietic stem cell transplantation (HSCT) strategies are followed by a prolonged period of immune deficiency due to delayed T-cell reconstitution. Either Umbilical Cord (CB) blood transplant or CD34+ selected haplo-transplant provided similar T-cell lymphocytes (CD3+ and CD4+) recoveries at any time point, and recipients had significantly fewer CD4+ T-cells during the first six months compared to HLA-matched donors. The GMP generation of Human T lymphoid Progenitors (HTLP) that are competent to rapidly become in vivo differentiated functional and thymic-educated T-cells may overcome the post-transplant delayed immune reconstitution. Method: HTLP safety and efficacy to accelerate immune reconstitution is currently evaluated in 2 multicentric and single-arm clinical trials: after umbilical cord blood in adult hematologic malignancy (Eudract 2019-004883-23) and after partially HLA compatible CD34+ immune-selected allogeneic hematopoietic stem cell transplantation in Severe Combined Immune Deficiency (SCID) patients (Eudract 2018-001029-14). Results: We enrolled and treated six patients, 4 SCID and 2 adults with malignancy, with an average follow-up of 8.00 (range, 1.60 to 37.7) months. HTLP cell product was infused between D7 to D14 post-HSCT for SCID patients after ensuring the decrease of the ATG level while meaning for the adult patient; the expanded pro-T cells were injected at D0. The Pro-T manufacturing process allows to robustly expand CD34+ cells to HTLP with a median of 79.7% (range 54.6; 98.9) of differentiation (CD7+ CD3-) and a median fold of proliferation of 14.7 (range 8.80; 18.5). No chromosome instability was induced during the expansion. Patients received increasing doses ranging from 0.1 to 0.5 10 6 HTLP/kg. The amount of CD3+/kg was less than 11.2 (range 0; 588)/ kg. No early or mid-term toxicity due to the administration of HTLP has been reported for evaluable patients (6/6). One SCID patient died on D53 because of severe VOD. Primary engraftment was confirmed in 4 out of 5 patients. Interestingly, despite the gradual increase of doses, there was no aGVHD over grade >2. Preliminary efficacy results suggest that circulating CD3+ CD4+ TCRαβ+ T cells > 50/μl before M4 depended on the increased infused dose of HTLP and an intrathymic paracrine effect. Notably, there was no viral infection disease or relapse during the outcome. Discussion conclusion: First infusions of HTLP in both clinical trials confirmed the safety and reproducible GMP manufacturing. HLTP offers an exciting perspective for improving immune reconstitution in alternative hematopoietic transplants.

Talquetamab + Pomalidomide in Patients with Relapsed/Refractory Multiple Myeloma: Safety and Preliminary Efficacy Results from the Phase 1b MonumenTAL-2 Study

Introduction: Talquetamab (tal) is a T-cell redirecting bispecific antibody (BsAb) targeting GPRC5D and CD3. GPRC5D is a novel antigen that is highly expressed on malignant plasma cells but has low expression on B cells and normal plasma cells. Tal has demonstrated deep and durable responses, including in high-risk populations, and a clinically manageable safety profile in patients (pts) with relapsed/refractory multiple myeloma (RRMM) in the MonumenTAL-1 study (NCT03399799/NCT04634552). Pomalidomide (pom) is an established immunomodulatory drug (IMiD) that has direct on-tumor apoptotic activity and enhances immune activity. Combining pom with T-cell redirection therapy may lead to synergistic antimyeloma effects. We report initial efficacy and safety results of tal + pom from the MonumenTAL-2 study. Methods: MonumenTAL-2 (NCT05050097) is a multi-arm, phase 1b study of tal in combination with antimyeloma agents in pts with MM. Pts received the recommended phase 2 doses of subcutaneous tal 0.4 mg/kg weekly (QW) or 0.8 mg/kg every other week (Q2W), with step-up dosing, + oral pom 2 mg daily (dose escalation to 4 mg daily permitted) starting in cycle 2. Pts received ≥2 prior lines of therapy (LOT) including a proteasome inhibitor and an IMiD; prior T-cell redirection therapies including BsAbs and chimeric antigen receptor (CAR)-T along with prior pom exposure were permitted. CRS and ICANS were graded by ASTCT criteria; all other adverse events (AEs) were graded by CTCAE v5.0. Response was assessed by IMWG criteria. Efficacy endpoints are presented as individual cohorts (QW and Q2W); safety is presented across both cohorts. Results: As of June 5, 2023, 35 patients were enrolled with a median follow-up of 11.4 months (range, 1.2-14.9) in the QW cohort (N=16) and 7.7 months (range, 1.6-10.8) in the Q2W cohort (N=19). Median ages were 69.5 years (range, 49-78) and 63.0 years (range, 43-76), respectively; 41.7% and 33.3% of pts had high-risk cytogenetics (del[17p], t[4;14], or t[14;16]) and 12.5% and 10.5% of pts had extramedullary disease, respectively. Median prior LOT were 3 in both cohorts; 25.0% and 21.1% were triple-class refractory, respectively, and 6.3% were penta-drug refractory (all in QW cohort). Prior treatments included CAR-T (18.8% and 0%), BsAb (6.3% and 0% [0% refractory]), and anti-CD38 Ab (75.0% and 73.7% [56.3% and 36.8% refractory]) in the QW and Q2W cohorts, respectively; 31.3% and 15.8% had prior pom exposure (18.8% and 5.3% refractory). All pts had ≥1 AE; most common were dysgeusia (77.1%), CRS (74.3%; most grade 1/2, 2.9% grade ≥3), and neutropenia (60.0%). Grade 3/4 AEs occurred in 88.6% of pts; most common were neutropenia (48.6%), anemia (25.7%), and thrombocytopenia (20.0%). Nail, skin, and rash toxicities occurred in 65.7%, 40.0%, and 20.0% of pts (majority grade 1/2 with no discontinuations), respectively. ICANS occurred in 2 pts (both grade 1). Infections occurred in 71.4% of pts (22.9% grade 3/4); most common were pneumonia (20.0%) and COVID-19 (14.3%). AEs led to dose reduction or schedule change of tal in 34.3% of pts and dose reduction of pom in 31.4% of pts. Two pts (5.7%) in the Q2W cohort had AEs, myocardial infarction and pulmonary embolism (PE), that led to treatment discontinuation (not drug related). One death due to PE occurred (same pt who discontinued treatment). ORR was 86.7% and 83.3% in the QW and Q2W cohorts, respectively, with ≥CR in 60.0% and 44.4% and ≥VGPR in 86.7% and 77.8%, respectively. ORRs were consistent across pt subgroups (>80% independent of prior pom or CAR-T exposure). Median time to first response was 1.0 month (range, 0.9-2.1) in the QW cohort and 1.3 months (range, 0-4.8) in the Q2W cohort. At 6 months, 100% of responders were still responding in both cohorts. Median DOR and PFS were not reached, with 6-month PFS rates of 93.3% (QW) and 88.9% (Q2W). Conclusions: In this first reported combination of a GPRC5D-targeted therapy and an IMiD, tal + pom showed rapid, deep responses in pts with RRMM and ≥2 prior LOT. The safety profile of the combination, including grade 3/4 hematologic toxicity, was consistent with the individual agents, with no evidence of additive hematologic toxicities; additionally, there were low rates of treatment discontinuation due to AEs. The promising efficacy and manageable safety profile of this combination further supports tal as a versatile combination partner and warrants further evaluation of this regimen.