Dose Cohorts Research Articles

CD19/BCMA dual-targeting FasTCAR-T GC012F for patients with relapsed/refractory B-cell non-Hodgkin lymphoma: An update.

e19045 Background: CD19-directed CAR-T cell therapy has been demonstrated to be a valuable treatment option for relapsed/refractory B-cell non-Hodgkin’s lymphoma (r/r B-NHL). It has been shown that between 39% and 97% of clinical samples of B-NHL also express BCMA. To further improve safety and efficacy, we have developed GC012F, a CD19 and BCMA dual-targeting CAR-T, manufactured using the novel next-day FasT CAR-T process, for the treatment of r/r B-NHL. The data from an investigator-initiated trial of GC012F for r/r B-NHL were reported at ASCO 2023 (# 7562). Here, we present updated results of the trial, including more pts and a longer follow-up period. Methods: This is a single-arm, open label trial (ChiCTR2100047061). The patients (pts) were enrolled and treated with a single infusion of GC012F in escalating dosing cohorts after a standard lymphodepletion regimen. The primary objectives of this study were safety and tolerability; the secondary were pharmacokinetics and efficacy. Cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS) were graded by ASBMT 2019, adverse effects were evaluated according to CTCAE 5.0. Efficacy assessment of GC012F was referred to the Lugano criteria. Results: As of data cut-off on January 30th, 2024, with a median of 410.5 days (range: 28 - 839) of follow-up, all pts received single GC012F infusions at dose levels ranging from 3.7×104 to 3×105 CAR-T/kg. The median age was 49.5 years (range: 18 - 67). Ten pts were Ann Arbor stage III/IV disease. All pts lymphoma samples expressed CD19, and 9 out of 11 expressed BCMA. Ptsreceived a median of 2 prior lines (range: 2 - 3) of therapy including rituximab and anthracyclines. Two ptsreceived the auto-HSCT previously. 91.7% (11/12) of the pts achieved ORR at month 3 post GC012F infusion; 66.7% (8/12) CR at month 6 and 60% (6/10) CR at month 12, respectively. To date, the longest duration of remission is 27.0 months. No dose-limiting toxicities were observed. One pt had grade 3 CRS and recovered within 2 days. No ICANS were observed. Grade ≥ 3 hematologic toxicities included lymphocytopenia (11/12), neutropenia (11/12) and leukopenia (10/12). All TEAEs were resolved after treatment with standard of care and supportive care. The median peak copy number of CAR-T cells in the peripheral blood was 70,083 copies/μg DNA (range: 6,876 - 185,039), and the median peak time was 14 days (range: 9 - 21). CAR-T cells were also detected in tumor biopsies from all six pts tested. In five pts at progressive disease, the primary or new lesions were CD19 positive, and no CAR-T cells were detected. Conclusions: This first-in-human trial of GC012F for the treatment of r/r DLBCL showed a manageable safety profile and promising clinical responses and a long-lasting duration of a remission. Overall, CD19-BCMA dual targeting CAR-T product GC012F is a promising therapy for r/r DLBCL pts and longer follow-up is ongoing. Clinical trial information: ChiCTR2100047061 .

Phase 1 study of BDTX-1535, an oral 4th generation covalent EGFR inhibitor, in patients with recurrent glioblastoma: Preliminary dose escalation results.

2068 Background: Epidermal growth factor receptor ( EGFR) gene is the most frequently altered oncogenic driver in glioblastoma (GBM). In-frame deletion alterations (e.g., EGFRvIII) and missense mutations co-occur in the setting of EGFR gene amplification and are characterized as a hallmark of disease pathogenesis in GBM. BDTX-1535 is an oral, highly potent, brain penetrant, selective, irreversible 4th generation tyrosine kinase inhibitor that targets EGFR alterations in GBM and NSCLC. Preliminary results of the Phase 1 dose escalation study (NCT05256290) of patients with recurrent GBM (rGBM) are presented here. Methods: BDTX-1535-101 is a first-in-human study that enrolled patients with either rGBM harboring EGFR alterations following standard of care or patients with locally advanced or metastatic EGFR mutated NSCLC that progressed on prior EGFR TKIs. Using an adaptive Bayesian optimal interval design in the Phase 1 part, patients were enrolled at increasing dose cohorts and were treated daily for 21-day cycles until treatment discontinuation. The primary objective was to determine the BDTX-1535 recommended Phase 2 dose based on the overall safety, PK, pharmacodynamics, and preliminary antitumor activity. Results: Twenty-seven patients with rGBM were enrolled in the Phase 1 cohort that consisted of 54 patients in total including 27 patients with NSCLC. Patients were treated across seven dose levels (15mg – 400mg QD). The mean age of patients with rGBM was 58.7 years (range 41-85) with 96% of patients with previous temozolomide (TMZ) treatment and a median of 2 lines of prior therapy (range 1-4). The most common all-grade treatment-related AEs across all cohorts were rash (78%), diarrhea (41%), fatigue (15%), stomatitis (11%), decreased appetite (11%), nausea (11%) and paronychia (11%). Gr 3 TRAEs ≥ 10% included rash (19%) reported at 300 or 400 mg QD doses. Plasma exposure of BDTX-1535 increased dose proportionally and had a half-life of ~15h, supporting once daily dosing. The maximum tolerated dose (MTD) is 300 mg QD. Among 19 evaluable patients for response based on RANO criteria, 1 confirmed partial response was observed and 8 patients achieved stable disease. Five patients remained on BDTX-1535 with stable disease for an extended period (>5 months) who previously performed poorly on TMZ with short treatment duration, and 1 patient continues on BDTX-1535 after 16 months of treatment. Conclusions: BDTX-1535 was well-tolerated up to 300mg daily, which is the MTD, and promising preliminary clinical activity was observed in patients with rGBM after relapse on standard of care treatment. Given the inability to reconfirm EGFR status at the time of treatment with BDTX-1535 in this Phase 1 trial, further exploration of BDTX-1535 in a “window of opportunity” study is ongoing (NCT06072586). Clinical trial information: NCT05256290 .

#1342 Updated results from the RUBY-3 study of povetacicept, an enhanced dual BAFF/APRIL antagonist, in autoantibody-associated glomerulonephritis

Abstract Background and Aims Inhibition of BAFF and/or APRIL has shown promise in IgA nephropathy (IgAN), systemic lupus erythematosus (SLE), lupus nephritis (LN), and primary membranous nephropathy (pMN), and has the potential to exert a disease-modifying effect. Povetacicept (ALPN-303) is an Fc fusion protein of a variant TACI domain engineered for more potent dual BAFF/APRIL inhibition than wild-type TACI or anti-BAFF or anti-APRIL antibodies. In a previous report, povetacicept 80 mg every 4 weeks was initially well tolerated and demonstrated promising, clinically meaningful reductions in urine protein to creatinine ratio (UPCR) and Gd-IgA1 in participants with IgAN (Tumlin J, et al. Poster TH-PO1125 presented at ASN 2023). Updated data are reported here. Method RUBY-3 is an open-label, multiple ascending dose, phase 1b/2a study of povetacicept 80 or 240 mg administered subcutaneously once every 4 weeks. Eligible participants are aged ≥18 years with biopsy-confirmed IgAN, LN, or pMN and on maximally tolerated ACE inhibitor/ARB therapy, with well-controlled blood pressure, and disease-specific immunosuppressive therapy where applicable. The primary objective is safety; secondary objectives include pharmacokinetics, pharmacodynamics, immunogenicity, biomarkers, and efficacy. Results As of 1 Dec 2023, 12 participants with IgAN have enrolled and received povetacicept 80 mg, with 7 (58%) having received ≥24 weeks of treatment. Povetacicept continues to be well tolerated, with the majority of treatment-emergent adverse events being of low grade. There have been no incidences of severe hypogammaglobulinemia (IgG <3 g/L) or severe infections. Povetacicept 80 mg was associated with a UPCR reduction of 52.6% at 24 weeks (n = 7). Reductions in Gd-IgA1, stable renal function, and pharmacodynamically expected decreases in immunoglobulin levels were also observed. Additional results from the 80 mg cohort with longer duration of follow-up, as well as initial results from the 240 mg dosing cohort, are planned to be presented. Conclusion Povetacicept remains well tolerated with multiple dosing and continues to demonstrate very promising activity in IgAN, strongly supporting further study in IgAN as well as other glomerulonephritis and autoantibody-associated diseases.

#1003 Safety, tolerability, pharmacokinetics, and pharmacodynamics of multiple ascending doses of AZD2373, an antisense oligonucleotide targeting APOL1

Abstract Background and Aims APOL1 mediated kidney disease (AMKD) is associated with toxic gain of function variants in people of African ancestry carrying the high-risk APOL1 genotypes (G1 and G2). APOL1 protein is part of the innate immune system but not considered essential. AZD2373, an antisense oligonucleotide that targets APOL1 mRNA to reduce its protein synthesis, is in development for AMKD. In genomic APOL1-transgenic mice, AZD2373 reduced APOL1 expression in kidney and liver, reduced plasma APOL1 protein concentration, and prevented development of IFN-γ induced proteinuria in high-risk genotype mice. In a single ascending dose study (NCT04269031), AZD2373 was well tolerated. We assessed the safety and tolerability of AZD2373 in a multiple ascending dose study including pharmacokinetics, and pharmacodynamic effect on APOL1 plasma protein levels. Method In this phase 1, randomized, single-blind, placebo-controlled study (NCT05351047) in healthy male volunteers of West African ancestry, participants were enrolled after a pre-screening study where they were genotyped for APOL1 prospectively; 18 participants had either 1 copy or 2 copies of the G1/G2 APOL1 high-risk allele. Low, medium and high dose cohorts each with 8 participants each receiving six weekly subcutaneous injections of either AZD2373 (n = 6) or placebo (n = 2) and were subsequently followed up for 9-weeks post-last dose. The primary objective was safety and tolerability; secondary objectives included assessment of pharmacokinetics and pharmacodynamics of AZD2373. Results In total, 24 participants were randomized and completed the study. No major safety and tolerability concerns were reported up to the highest dose of AZD2373 administered. The most common adverse event was injection site reactions which were dose-dependent, mild to moderate in severity and did not lead to treatment discontinuation. After dosing, AZD2373 had a rapid distribution phase (hours) and prolonged elimination phase (days to weeks). Clearance was similar across dose levels after single and repeated dosing, and the renal contribution to overall clearance was minimal. Exposure generally increased in a dose proportional manner. Plasma APOL1 was knocked down in a dose dependent manner (Figure). Conclusion Repeated doses of AZD2373 were safe and well tolerated, reducing plasma APOL1 concentrations in a dose- and time-dependent manner in healthy males of West African ancestry.

Long-Term Follow-Up of Phase I Trial of Oncolytic Adenovirus-Mediated Cytotoxic and Interleukin-12 Gene Therapy for Treatment of Metastatic Pancreatic Cancer.

The long-term follow-up findings of the phase I trial evaluating the efficacy of oncolytic adenovirus-mediated cytotoxic and interleukin-12 gene therapy in metastatic pancreatic cancer (mPC) seem very promising. The study employed a replication-competent Adenovector in combination with chemotherapy in a dose-escalation format. The trial demonstrated a clinically meaningful median overall survival (OS) benefit, with patients in the highest dose cohort exhibiting an impressive median OS of 18.4 months. This contrasts starkly with patients receiving lower doses who experienced a median OS of 4.8 and 3.5 months, respectively. Remarkably, subject number 10, who received the highest dose, demonstrated an extraordinary survival of 59.1 months, presenting a compelling case for further exploration. Additionally, this patient displayed complete responses in lung and liver metastases, a rare occurrence in mPC treatment. Statistical analyses supported the observed survival benefit. The unprecedented OS results emphasize the potential of this treatment strategy and pave the way for future investigations into this promising gene therapy approach.

Abstract PO4-18-07: A dose escalation and cohort expansion study of the CDK9 inhibitor KB-0742 in triple negative breast cancer and transcriptionally addicted relapsed or refractory solid tumors

Abstract Background: MYC deregulation is a hallmark of triple negative breast cancer (TNBC) and is associated with aggressive tumors and poor clinical outcomes. Although MYC remains undrugged, targeting of its cofactors has emerged as an attractive strategy to inhibit MYC oncogenic activity. Cyclin-dependent kinase 9 (CDK9) is a critical regulator of oncogenic MYC expression and an important MYC cofactor. KB-0742 is an oral CDK9 inhibitor that demonstrates promising preclinical activity against TNBC. In a real-world cohort, TNBCs have higher MYC expression and higher rates of MYC genomic amplification than other breast cancer subtypes. In primary patient-derived cell lines, KB-0742 treatment results in stronger cytotoxic effects in TNBC as compared to other subtypes. In patient-derived organoids and patient-derived xenografts, CDK9 inhibition by KB-0742 drives antiproliferative and anti-tumor growth effects, including in models that are resistant to standard of care. KB-0742 strongly downregulates MYC protein levels at doses that only partially inhibit CDK9 activity, suggesting a therapeutic window for tumor-specific activity (Saffran, D.C. et al, 2021). KB-0742 is currently being evaluated in a phase 1/2 dose escalation and cohort expansion study in patients with TNBC and other transcriptionally addicted tumors (NCT04718675). Trial design: This phase 1/2 study includes two parts: dose escalation (part 1) and cohort expansion (part 2). Part 2 includes cohort A (solid tumors with high prevalence of MYC overexpression including TNBC, non-small cell lung cancer and ovarian) and cohort B (other transcriptionally addicted tumor types including sarcomas, adenoid cystic carcinoma, nut midline carcinoma and small cell lung cancer). KB-0742 is dosed orally once daily for 3 consecutive days, followed by 4 days, off on a weekly basis in 28-day cycles until unacceptable toxicity or disease progression. Eligibility criteria: Part 1 dose escalation is open to patients with relapsed or refractory solid tumors. Part 2 is defined by tumor indications in cohorts A and B. Eligibly criteria include age > 18 years (≥ 12 years old and with a body weight ≥ 40 kg part 2 for cohort B), acceptable organ function, and ECOG PS < 2. Specific aims: Primary objectives include evaluation of pharmacokinetics (PK), pharmacodynamics (PD), safety, tolerability, preliminary anti-tumor activity, and identifying a maximum tolerated dose (MTD) and recommended phase 2 dose (RP2D). PK measurements include Cmax, tmax, AUC0-last, accumulation ratio (Racc) and t1/2. Safety data will be evaluated per the National Cancer Institute Common Terminology Criteria for Adverse Events (NCI-CTCAE) v5.0. The Modified Continuous Reassessment Method (mCRM) (Goodman et al., Stat Med 1995) will guide dose escalation and MTD. RP2D nomination is informed by PD in peripheral blood mononuclear cells using assays to evaluate phosphorylation of the CDK9 substrate serine 2 on the RNA Polymerase II C-terminal domain (pSER2) and CDK9-responsive gene expression. Radiographic tumor response to KB-0742 in patients is assessed every other cycle starting from cycle two after treatment using RECIST 1.1 criteria. Target accrual: Targeted total enrollment is 170 patients. For additional information, contact clinicaltrials@kronosbio.com Citation Format: Monica Mita, Alain Mita, Miguel Villalona-Calero, Noah Federman, Drew Rasco, David Spigel, Jia Luo, Gregory Cote, Richard Cutler, Pavan Kumar, Crystal MacKenzie, Charles Lin, Jorge DiMartino, Elizabeth Olek, Brian Van Tine. A dose escalation and cohort expansion study of the CDK9 inhibitor KB-0742 in triple negative breast cancer and transcriptionally addicted relapsed or refractory solid tumors [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 PO4-18-07.

Abstract PO4-04-01: Antitumor activity and safety of sacibertinib (Hemay022) in combination with endocrine therapy in patients with ER and HER2 both positive metastatic breast cancer: A phase Ib study

Abstract Abstract PURPOSE Sacibertinib (Hemay022) is a novel irreversible tyrosine kinase inhibitor (TKI) blocking epidermal growth factor receptor and human epidermal growth factor receptor 2 (HER2). This study aimed to explore the safety and efficacy of sacibertinib plus endocrine therapy in patients with estrogen receptor-positive ( PATIENTS AND METHODS Using a phase 1b 3+3 dose escalation and expansion study design, patients with ER+/HER2+ MBC were treated with sacibertinib (200mg-500mg daily) plus endocrine therapy including exemestane, letrozole, fulvestrant. The safety, pharmacokinetic and clinical efficacy, including objective response rate (ORR), clinical benefit rate (CBR), disease control rate (DCR) and progression-free survival (PFS) were assessed. RESULTS A total of 55 ER+/HER2+ MBC patients pretreated with chemotherapy and anti-HER2 therapy were enrolled in the study between March, 2018 and July, 2021. The incidence of ORR ranged from 17.6% to 42.9%, DCR ranged from 63.0% to 86.8%, CBR ranged from 42.3% to 69.7%, and the overall median PFS was 9.0 (95% CI, 5.5 ~ 11.00) months. In the 400 mg Sacibertinib plus exemestane cohort (N = 18), ORR was 38.9% (7/18), DCR was 72.2%(13/18), CBR was 66.7%(12/18), and median PFS was 8.9 months; In the 500 mg Sacibertinib plus exemestane cohort (N = 12), ORR was 25.0%(3/12), DCR was 100.0%(12/12), CBR was 50.0%(6/12), and median PFS was 9.0 months. The ORR, CBR, and DCR were better in the 400 mg and above dose cohorts than in the 200 mg and 300 mg cohorts. The DCR of the 500 mg combined with exemestane cohort was better than that of the other dose cohorts. Sacibertinib plus endocrine therapy was well-tolerated without dose-limiting toxicities. The most frequent grade 3 adverse events included diarrhoea (9.1%), leucopenia(5.5%), neutropenia (3.6%). One (1.8%) had grade 4 hydropericardium. CONCLUSION Sacibertinib plus endocrine therapy had a favorable safety profile and antitumor activity in patients with ER+/HER2+ MBC, 400-500mg daily showed more efficacy, supporting further assessment in randomized studies. This figure showed response of Sacibertinib plus endocrine therapy in ER+/HER2+ metastatic breast cancer. Citation Format: Hui-Ping Li, Qingyuan Zhang, Ruyan Zhang, Yaxin Liu, Xianjun Hu. Antitumor activity and safety of sacibertinib (Hemay022) in combination with endocrine therapy in patients with ER and HER2 both positive metastatic breast cancer: A phase Ib study [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 PO4-04-01.

Abstract PO2-27-11: Antitumor efficacy and safety of sacibertinib (Hemay022) in combination with endocrine therapy in patients with ER+ and HER2+ metastatic breast cancer: A phase Ib study

Abstract PURPOSE Sacibertinib (Hemay022) is a novel irreversible tyrosine kinase inhibitor (TKI) blocking epidermal growth factor receptor and human epidermal growth factor receptor 2 (HER2). This study aimed to explore the safety and efficacy of sacibertinib plus endocrine therapy in patients with estrogen receptor-positive (ER+) and HER2-positive (HER2+) >metastatic breast cancer (MBC). PATIENTS AND METHODS Using a phase 1b 3+3 dose escalation and expansion study design, patients with ER+/HER2+ MBC were treated with sacibertinib (200mg-500mg daily) plus endocrine therapy including exemestane, letrozole, fulvestrant . The safety, pharmacokinetic (PK) and clinical efficacy, including objective response rate (ORR), clinical benefit rate (CBR), disease control rate (DCR) and progression-free survival (PFS) were assessed. (Clinical Trials.gov identifier: NCT03308201). RESULTS A total of 55 ER+/HER2+ MBC patients pretreated with chemotherapy and anti-HER2 therapy were enrolled in the study between March, 2018 and July, 2021. Fifty-five patients were included in safety analysis and 51 patients were assessed for efficacy analysis. Sacibertinib plus endocrine therapy was well-tolerated without dose-limiting toxicities. The overall median PFS was 9.0 months [95% confidence interval (95% CI), 5.5 ~ 11.0]. The ORR, CBR, and DCR were better in the 400 mg and 500mg dose cohorts than in the 200 mg and 300 mg cohorts. The DCR of the 500 mg combined with the exemestane cohort was better than that of cohorts of other doses. In the 400 mg sacibertinib plus exemestane cohort (N = 18), ORR was 38.9% (7/18) , DCR was 72.2%(13/18), CBR was 66.7%(12/18), and median PFS was 8.9 months (95%CI, 2.7 ~ 16.4 ) ; In the 500 mg sacibertinib plus exemestane cohort (N = 12), ORR was 25.0% (3/12), DCR was 100%(12/12), CBR was 50.0%(6/12), and median PFS was 9.0 months (95%CI, 2.1~NA. Treatment-emergent AEs (TEAEs) were mostly within grades 1–2. The most frequent grade 3 TEAE was diarrhea (9.1%). One (1.8%) had grade 4 abnormal liver function. CONCLUSIONS Sacibertinib plus endocrine therapy had a favorable safety profile and antitumor activity in patients with ER+/HER2+ MBC, 400 -500mg sacibertinib daily showed more efficacy, supporting further assessment in randomized studies. Summary of efficacy data(EAS) NOTE. NA, not available (because cannot be calculated) Treatment-Emergent Adverse Events Occurring in ≥ 10% of Patients in the Safety Population Abbreviations: ALT, alanine aminotransferase; AST, aspartate aminotransferase; Waterfall plot of best change rate in target-lesion size from baseline Citation Format: Hui-Ping Li, Qingyuan Zhang, Ruyan Zhang, Yaxin Liu, Chang Liu, Xianjun Hu. Antitumor efficacy and safety of sacibertinib (Hemay022) in combination with endocrine therapy in patients with ER+ and HER2+ metastatic breast cancer: A phase Ib study [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 PO2-27-11.

Abstract PS01-09: Early Results of a Phase I Pre-Operative Single Fraction Ablative Trial for Early Stage Breast Cancer

Abstract Objective(s): To explore the impact of pre-operative single fraction stereotactic ablative partial breast irradiation (SPBI) dose escalation (30, 34, or 38Gy) on toxicity and tumor response for early-stage hormone receptor (HR)+ breast cancer in an interim analysis of an expanded cohort phase I dose escalation study (NCT04040569). Methods: Eligible patients (pts) have < 3 cm, HR+, Her2 -, cN0 invasive breast carcinomas not requiring chemotherapy. Patients are treated on either MR LINAC, robotic radiosurgery, or cobalt stereotactic breast units. Endocrine therapy is started two weeks after SPBI. Surgery is completed 2-12 months after SPBI. The primary objective is to escalate single fraction SPBI to an ablative dose without exceeding maximum tolerable dose (MTD). Secondary endpoints include pathologic complete response (pCR), local control, toxicity, cosmesis, and distant disease-free survival. Near complete response (nCR) is defined as RCB 1 and Miller-Payne 4/5. Dose limiting toxicity (DLT) is defined as grade ≥3 toxicity or any grade 4/5 toxicity attributed to SPBI. Each dose cohort enrolls 7-15 pts. Dose escalation is permitted if 0/7, 2/9, ≤3/12, or ≤4/15 patients experienced a DLT within 90 days of SPBI. MTD is exceeded if more DLTs occur in any cohort. Results: From 12/2019 to 6/2023, 11 and 15 pts were treated with 30Gy and 34Gy, respectively. Rates of pCR/nCR are 37.5% for 30Gy versus 92.8% 34 Gy (p=0.01). At 30Gy, 8/11 pts (73%) underwent surgery with a median 4.3 (range 2.8-5.9) month interval from SPBI to surgery: 0/8 (0%) had a pCR and 3/8 (37.5%) had a nCR. At dose level 34Gy, 14/15 pts (93%) underwent surgery with a median 7.3 (range 5.9-12) month interval from SPBI to surgery: 6/14 (42.8%) had a pCR while 7/14 (50%) had a nCR. Of the 8 pts with a nCR, 50% had only 1-3mm of residual disease. The mean ki67 for the entire cohort was 12.0% +/- 6.9% at diagnosis and decreased to 1.4 +/-2.3% at surgery. 13/14 (92.8%) pts with residual disease had a ki67 < 3% after surgery and SPBI. There were 33 acute grade 1; 2 acute grade 2 (breast pain and dermatitis); and 10 late grade 1 [1 grade 2 (breast pain), and 1 grade 3 (slow healing wound) in an uncontrolled diabetic] toxicities. Conclusion: First study to show pre-operative SPBI up to 34Gy in a single fraction was safe and effective for early-stage HR+ breast cancer. Escalating the dose has achieved a dramatic improvement in pCR/nCR (92.8%) suggesting this is an exciting approach for potentially eliminating tumor with radiation/endocrine therapy alone in early stage breast cancer and potentially paving a path towards non-surgical management in highly selected patients. Citation Format: Asal Rahimi, A Marilyn Leitch, Baṣak Dogan, Prasanna Alluri, Deborah Farr, Mona Arbab, Stephen Seiler, Nathan Kim, Rachel Wooldridge, Nisha Unni, Chika Nwachukwu, Ina Patel, You Zhang, David Parsons, Anvy Nguyen, Howard E Morgan, Heather McArthur, Sunati Sahoo, Robert Timmerman. Early Results of a Phase I Pre-Operative Single Fraction Ablative Trial for Early Stage 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 PS01-09.

Abstract PO2-27-01: TFX06, a next-generation oral CERAN/SERD, shows favorable safety and PK profile, extracranial and intracranial efficacy in patients with ER+/HER2- breast cancer: Preliminary results from a phase 1/2 first-in-human trial

Abstract Aims: TFX06 is an investigational oral complete estrogen receptor (ER) antagonist (CERAN) and selective ER degrader (SERD) (Wu J, et al., 2023 AACR annual meeting). A Phase 1/2, multicenter, open-label dose-escalation and dose-expansion study (CTR20230789) was initiated in China to evaluate TFX06 in previously heavily treated patients with ER+/HER2- locally advanced and/or metastatic breast cancer. The primary objectives were to assess safety and tolerability, recommended Phase 2 dose (RP2D), and pharmacokinetics (PK). Methods: A 3+3 dose-escalation design was implemented. TFX06 tablets were orally administered at 60 mg/100 mg daily for 28 days of treatment cycle until disease progression or intolerant to TFX06. As of the cut-off date (Sept. 15, 2023), the Phase 1 study enrolled five patients with Stage IV diseases with distant metastases. Three were treated with TFX06 at 60 mg, the starting dose and two at the next dose level of 100 mg. Median age of patients were 50 years (39-65) with a ECOG score of 0-1. Two out of five patients carried estrogen receptor 1 (ESR1) mutations (ctDNA). Prior anticancer treatments included one or two lines of endocrine therapies, including fulvestrant, and/or one or two lines of chemotherapies. Clinical responses by investigator according to RECIST v1.1 were performed every two cycles to explore preliminary efficacy. Results: Three patients in 60 mg and one in 100 mg dose cohorts completed dose-limiting toxicity (DLT) observation period. No DLT observed. All treatment related adverse events (TRAEs) were grade 1-2 in severity, including nausea, drowsiness, decreases in WBC and neutrophils, and anemia. Analyses of plasma concentrations of TFX06 in all three patients receiving 60 mg revealed a similar PK profile with small variations in Cmax. The average steady-state Cmax and Cmin of TFX06 were 101 ng/mL and 65 ng/mL, respectively, and the Cmax of TFX06 was approximately 4-fold higher than that of fulvestrant administered intramuscularly at 500 mg in clinic (28 ng/mL). Two patients in the 60 mg cohort were evaluable for response assessment. One patient discontinued due to progressive disease (PD) after two cycles of treatment. This patient experienced a 17.1% decrease in target lesions in the lung; however, new metastases to bone observed. The other patient who carried ESR1 D538G mutation showed a decrease of 91% in ESR1 mutation burden 8 days after treatment, and a decrease of 34.2% in target lesions (partial response, PR), including a substantial shrinkage of 78.6% in the brain lesion (target lesion), as well as complete responses (CR) of non-target lesions in lung after 4 cycles of treatment. This patient remains on the study as of the cut-off date. Conclusions: Based on the preliminary results, oral administration of TFX06 at 60 or 100 mg once daily had favorable safety and PK profiles. TRAEs, such as gastrointestinal toxicities, bradycardia, and visual disturbances were not observed. Pleasingly, TFX06 demonstrated early extracranial and intracranial antitumor activity (PR) in a patient with a brain metastasis. Citation Format: Zhaojian Fu, Zhiye Zhang, Jia Song, Yang Chen, Douglas Fang, Wei Sha, Jian Zhang, Charles Ding. TFX06, a next-generation oral CERAN/SERD, shows favorable safety and PK profile, extracranial and intracranial efficacy in patients with ER+/HER2- breast cancer: Preliminary results from a phase 1/2 first-in-human trial [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 PO2-27-01.

Clinical outcomes of patients receiving three versus four doses of methotrexate with concomitant antithymocyte globulin in match unrelated donor allogeneic stem cell transplant: A single-center experience.

Methotrexate (MTX) doses on days +1, +3, +6, and +11 after match unrelated donor allogeneic stem cell transplant (MUD HSCT) is a common graft-versus-host disease (GVHD) prophylaxis regimen. However, the overlapping toxicity of MTX with conditioning chemotherapy sometimes warrants the omission of the fourth dose of MTX. Prior single-institution studies showed conflicting results comparing the outcomes of patients who received three versus four doses of MTX, but to our knowledge, the effect of concomitant antithymocyte globulin (ATG) has not been reported. Charts of patients who underwent MUD HSCT between 2009 and 2023 were reviewed. Patients received rabbit ATG (Thymoglobulin), given at 0.5mg/kg on day -3, 2mg/kg on day -2, and 2.5mg/kg on day -1. MTX is given at 15mg/m2 on day +1 and 10mg/m2 on days +3, +6, and +11. Severe mucositis was the most common indication for day +11 MTX omission (82%). We identified 292 patients (116 in 3 dose cohort and 176 in 4 dose cohort). Median follow-up was 23 months (range 1-151). Patients in the 4 doses cohort were more frequently male (68% vs. 50%, p<0.01), received a reduced intensity conditioning regimen (38.0% vs. 22%, p<0.01), were older (median 58 vs. 54 years, p=0.02), and received a transplant in the earlier era (median HSCT year 2014 vs. 2018, p<0.01). A statistically significant difference was not evidenced between the cohorts for the following outcomes: acute GVHD (aGVHD) (HR 1.1, 95% CI 0.9-1.5), chronic GVHD (cGVHD) (HR 1.3, 95% CI 0.8-1.6), relapse-free survival (RFS) (HR 1.0, 95% CI 0.6-1.5), non-relapse mortality (NRM) (HR 1.4, 95% CI 0.9-2.2), and overall survival (OS) (HR 1.2, 95% CI 0.9-1.7). Both cohorts had similar median time to neutrophil engraftment at 14 days. When ATG is incorporated, omission of day +11 MTX does not significantly impact the rate of engraftment or cumulative incidence of aGVHD, cGVHD, RFS, NRM, and OS.

Phase I DAVIO Trial: EYP-1901 Bioerodible, Sustained-Delivery Vorolanib Insert in Patients With Wet Age-Related Macular Degeneration

PurposeTo evaluate safety and tolerability of EYP-1901, an intravitreal insert containing vorolanib, a pan–vascular endothelial growth factor (VEGF) receptor inhibitor packaged in a bioerodible delivery technology (Durasert E™) for sustained delivery, in patients with wet age-related macular degeneration (wAMD) previously treated with anti-VEGF therapy. DesignPhase 1, multicenter, prospective, open-label, dose-escalation trial. ParticipantsPatients with wAMD and evidence of prior anti-VEGF therapy response. MethodsPatients received a single intravitreal injection of EYP-1901. Main Outcome MeasuresThe primary objective was to evaluate safety and tolerability of EYP-1901. Secondary objectives assessed biologic activity of EYP-1901 including best-corrected visual acuity (BCVA) and central subfield thickness (CST). Exploratory analyses included reduction in anti-VEGF treatment burden and supplemental injection-free rates. ResultsSeventeen patients enrolled in the 440 μg (3 patients), 1030 μg (1 patient), 2060 μg (8 patients), and 3090 μg (5 patients) dose cohorts. No dose-limiting toxicity, ocular serious adverse events (AEs), or systemic AEs related to EYP-1901 were observed. There was no evidence of ocular or systemic toxicity related to vorolanib or the delivery technology. Moderate ocular treatment-emergent AEs (TEAEs) included reduced visual acuity (2/17) and retinal exudates (3/17). One patient with reduced BCVA had 3 separate reductions of 17, 18, and 16 letters, and another had a single drop of 25 letters. One severe TEAE, neovascular AMD (i.e., worsening/progressive disease activity), was reported in 1 of 17 study eyes but deemed unrelated to treatment. Mean change from baseline (CFB) in BCVA was –3.7 letters and –5.4 letters at 6 and 12 months. Mean CFB in CST was +1.7 μm and +2.3 μm at 6 and 12 months. Reduction in treatment burden was 76% and 72% at 6 and 12 months. Of 16 study eyes, 13, 9, and 6 were injection-free up to 3, 6, and 12 months. ConclusionIn the DAVIO trial (ClinicalTrials.gov identifier, NCT04747197), EYP-1901 had a favorable safety profile and was well tolerated in previously treated eyes with wAMD. Measures of biologic activity remained relatively stable following a single EYP-1901 injection. These preliminary data support ongoing Phase 2 and planned Phase 3 trials to assess efficacy and safety.

First-in-human study on pharmacokinetics, safety, and tolerability of single and multiple escalating doses of PA9159 nasal spray, a highly potent glucocorticoid in healthy Chinese volunteers

ObjectivePA9159 (previously named VSG159) is a structurally novel and highly potent glucocorticoid that plays a role in the late development of autoimmune and inflammatory diseases. The current first-in-human ascending-dose study of the PA9159 nasal spray was conducted in healthy Chinese volunteers to evaluate its pharmacokinetics, safety, and tolerability. In addition, the effects of PA9159 on serum cortisol secretion were investigated. MethodsThis was a double-blinded, randomized, placebo-controlled clinical study that included four single-dose groups in the single ascending dose cohort (SAD) and two multiple-dose groups in the multiple ascending dose cohort (MAD), with dose ranges of 10–80 μg and 20–40 μg, respectively. PA9159 was administered bilaterally via nasal spray once only or once daily for seven days. Pharmacokinetic, safety, and tolerability profiles were evaluated. ResultsA total of 60 participants completed the study. PA9159 doses of up to 80 μg in the SAD and up to 40 μg in the MAD were shown to be safe and tolerable. The most common treatment-related AEs were mild and transient local nasal AEs. Morning serum cortisol levels approximately remained unchanged in both the single-dose and multiple-dose groups. PA9159 was quantified in 41.8 % (368/880) of the samples in all treatment groups, including 25.2 % (105/416) of the SAD and 56.7 % (263/464) of the MAD. The majority (>80.0 %) of PA9159 plasma concentrations ranged from 0.5 to 2 pg/mL in determined samples. The mean AUC0-t of PA9159 in the SAD was 0.91, 1.39±0.68, 11.40±9.91, and 46.30±25.80 h*pg/mL in the 10 to 80 ug single group. The mean terminal half-life time (t1/2) was 8.43 h and 8.97±2.28 h in 40 ug and 80 ug single group, respectively. The mean AUCss of PA9159 in the MAD was 31.70±7.04, 44.20±20.60 h*pg /mL, and the t1/2 was 16.00±4.18 h, 21.20±10.20 h in the 20 ug and 40 ug multiple groups, respectively. The median Tmax was approximately 6 h in both the SAD and MAD cohorts. ConclusionsThe PA9159 nasal spray was generally safe and well tolerated, and the effects of PA9159 on serum cortisol levels were limited. The plasma concentration and systemic exposure to PA9159 were very low. These findings support the necessity for further clinical studies on PA9159 nasal spray in patients suffering from allergic rhinitis.

Abstract CT185: A phase I clinical trial to evaluate the safety, tolerability, pharmacokinetics, pharmacodynamics and preliminary anti-tumor activity of BC3402 in advanced solid malignancies

Abstract Background: BC3402, an IgG4 monoclonal antibody (mAb) that targets TIM-3, is being developed for solid and hematological malignancies. In preclinical studies in immunocompetent cancers, BC3402 demonstrated synergy when combined with mAbs to PD-1 and/or CTLA-4, supporting a rationale for combination strategies in the clinic. As a first step, the safety, tolerability, pharmacokinetics (PK), pharmacodynamics, and preliminary anti-tumor activity of BC3402 monotherapy was evaluated in patients (pts) with advanced solid malignancies. Methods: In this phase I, open-label study, multiple doses of BC3402 were explored in pts with advanced solid cancers who had been previously treated with standard therapies to evaluate its safety and tolerability and recommend doses for further development. An accelerated titration design was used to select doses in the first two dose levels (0.02 and 0.2mg/kg IV Q3W) followed by a standard “3+3” design in the remainder of the study (1, 5, 10, 20 and 30 mg/kg IV Q3W). Results: Nineteen pts (median [range] age: 59 [29-73]; 63.2% male; 94.7% ECOG 1) were treated with at least one 3-week cycle of BC3402. DLT was not observed, and adverse events (AEs) were not dose related. The most common TEAEs (incidence ≥20%) and TRAEs (incidence ≥10%) were grade 1-2. The most common (incidence ≥10%) TEAE ≥ grade 3 was dysphagia (2/19 pts, 10.5%), which occurred in the 5 mg/kg and 10 mg/kg dose cohorts. Two pts reported grade 3 or above TRAEs – grade 3 hypertension (5 mg/kg) and grade 3 gamma-glutamyl transferase increase (10 mg/kg), There were neither dose interruptions nor treatment discontinuation due to AEs. There were no objective responses. Seven of 18 pts who were evaluable for tumor assessment had stable disease as best response with one pt (20 mg/kg dose cohort) with NSCLC having sustained reductions (32 weeks) in target lesions. Median Tmax values ranged from 1.08 to 2.96 hours, and mean T1/2 values ranged from 119 to 182 hours at doses ranging from 5-30 mg/kg. Exposure was linear in the dose range of 1 -30 mg/kg, and there was no drug accumulation after the second cycle. Receptor occupancy saturation was observed within the tested dose range. Based on these data, the RP2D was determined as 20mg/kg every 2 weeks or 30mg/kg every 3 weeks. Conclusions: BC3402 exhibited favorable safety profile and PK characteristics when administered as single infusion at doses ranging from 0.02 mg/kg to 30 mg/kg Q3W in pts with advanced solid cancers, and its safety profile supports further disease-directed studies in combination with other immune checkpoint inhibitors and/or rational therapeutic modalities. Citation Format: Yi-Long Wu, Huajun Chen, Sheng Wang, Rui Zhang, En-Tzu Tang, Weiwei Zhang, Kaicun Gu, Yiwei Wang, Yongjiang Hei. A phase I clinical trial to evaluate the safety, tolerability, pharmacokinetics, pharmacodynamics and preliminary anti-tumor activity of BC3402 in advanced solid malignancies [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 CT185.

Abstract CT158: A dose escalation and cohort expansion study of the CDK9 inhibitor KB-0742 in relapsed, refractory and transcriptionally addicted solid tumors

Abstract Background MYC transcriptional deregulation is a hallmark of cancer and is associated with poor clinical outcomes. MYC deregulated solid tumors including non-small cell (NSCLC), small cell lung cancer (SCLC), triple negative breast cancer (TNBC), and ovarian cancer are known for their aggressiveness and frequent relapse. Analysis of a real-world solid tumor cohort including NSCLC (n= 20,470), SCLC (n=1,517), TNBC (n=2,576) and ovarian cancer (n=1,667) demonstrated MYC family overexpression and/or genomic amplification in 47% to 87% of patients. Although MYC remains difficult to drug, targeting of its cofactors has emerged as an attractive strategy to inhibit MYC oncogenic activity. Cyclin-dependent kinase 9 (CDK9), a MYC cofactor, is a critical regulator of oncogenic MYC expression and activity. KB-0742 is a potent, selective, and orally bioavailable inhibitor of CDK9 with a long plasma half-life. KB-0742 is being evaluated in an ongoing Phase 1/2 study in advanced solid tumors (NCT04718675). Methods The Phase 1/2 study is being conducted in two parts: dose escalation and dose expansion. Part 1 dose escalation comprises patients with relapsed or refractory solid tumors. Part 2 dose expansion comprises patients with solid tumors that have a high prevalence of MYC overexpression including ovarian cancer, NSCLC, TNBC and SCLC. KB-0742 is dosed orally once daily for 3 consecutive days followed by 4 days off on a weekly basis in 28-day cycles until unacceptable toxicity or disease progression. Eligibility criteria include age &amp;gt; 18 years acceptable organ function and ECOG PS &amp;lt; 2. Up to 170 patients are planned to be enrolled in the study. Primary objectives include evaluation of pharmacokinetics (PK), pharmacodynamics (PD), safety, tolerability, and preliminary anti-tumor activity with the goal of identifying a maximum tolerated dose (MTD). Plasma PK measurements include Cmax, tmax, AUC0-last, accumulation ratio (Racc) and t1/2. Safety data will be evaluated per the National Cancer Institute Common Terminology Criteria for Adverse Events (NCI-CTCAE) v5.0. RP2D is informed by PD in peripheral blood mononuclear cells using assays to evaluate phosphorylation of the CDK9 substrate serine 2 on the RNA Polymerase II C-terminal domain (pSER2) and CDK9-responsive gene expression. Radiographic tumor response is assessed using RECIST 1.1 criteria. Exploratory objectives include assessment of KB-0742 PD in tumor tissue and profiling of treatment-related genomic, transcriptomic, and proteomic changes. The study is continuing as planned; the next data analysis will occur in 2024. Citation Format: Miguel Villalona Calero, Mark Agulnik, Monica Mita, Alain Mita, Noah Federman, Drew Rasco, David Spigel, Jia Luo, Glenn Hanna, Gregory Cote, Mohamad A. Salkeni, Rashmi Chugh, Natraj R. Ammakkanavar, Satish A. Shah, Amol Rao, Kamalesh Kumar Sankhala, Richard E. Cutler, Tressa Hood, Luis Carvajal, Crystal MacKenzie, Charles Lin, Jorge DiMartino, Elizabeth A. Olek, Brian Van Tine. A dose escalation and cohort expansion study of the CDK9 inhibitor KB-0742 in relapsed, refractory and transcriptionally addicted solid tumors [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 CT158.

Abstract CT059: Phase 1b trial Mipasetamab Uzoptirine (ADCT-601-102) dose escalation in patients with advanced bone and soft tissue sarcomas

Abstract Background: AXL is a cell surface receptor tyrosine kinase widely expressed in solid tumors (ST), including sarcomas. ADCT-601 (Mipasetamab uzoptirine; Mipa) is an antibody-drug conjugate comprising a humanized anti-AXL antibody conjugated via a cleavable linker to SG3199 (pyrrolobenzodiazepine dimer cytotoxin). Mipa demonstrated antitumor activity in pre-clinical mice models of sarcoma, adrenocortical carcinoma and pancreatic cancer, and clinical activity in ST patients (pts) in its first-in-human trial. Here, we report initial clinical data in pts with advanced bone and soft tissue sarcomas treated in dose escalation with Mipa. Objective: To characterize the safety and tolerability of Mipa in pts with sarcoma indications who exhausted standard of care therapy. Method: This is a phase 1b, open-label, dose-escalation, dose expansion study of Mipa (NCT05389462; EudraCT: 2021-00566-18). Pts received Mipa every 3 weeks (Q3W) at escalating dose levels, in a 3+3 dose escalation design. Results: As of 04 December 2023, 18 sarcoma patients (15 [83%], soft tissue sarcoma [STS] and 3 [17%] bone sarcoma), unselected for AXL expression, with a median number of 3 prior lines of therapy (1-10), were enrolled in 4 different dose cohorts: 7.5mg, 11mg, 13mg and 15mg. Reasons for treatment discontinuation were disease progression (10 pts [55.6%]), adverse events (3 pts [16.7%]) and consent withdrawal (2 pts [11.1%]). Treatment emergent adverse events (TEAE) were seen in 17 pts (94.4%). Most common TEAE (all grades and relationship [≥20%]) were palmar-plantar erythrodysesthesia syndrome (7 pts [38.9%]); anemia (6 pts [33.3%]); rash maculopapular (5 pts [27.8%]); cheilitis and constipation (4 pts each [22.2%]). TEAE≥grade 3 were seen in 9 pts (50%). Most common TEAE≥grade 3 (≥10%) were GGT increase (2 pts [11.1%]). Two dose limiting toxicities were seen: cheilitis grade 2 and grade 3 at 15mg and 13mg respectively. Cutaneous reactions, all grades, are more prominent in higher doses. Maximum tolerated dose (MTD) has not been established. In 17 sarcoma pts evaluable per RECISTv1.1, best overall response was partial response (PR) (2 pts [11.8%]), including a confirmed PR; stable disease (SD) (8 pts [47.1%]); progressive disease (7 pts [41.2%]). Tumor reductions was observed at 7.5mg, 11mg and 13mg. By week 12, 6/17 pts (35.3%) did not demonstrate PD . Initial IHC staining showed AXL expression in all sarcoma baseline biopsies tested so far. Initial pharmacokinetic (PK) data indicate exposures with moderate to marked interpatient variability; rapid clearance with no accumulation by Cycle 2. Updated biomarkers and PK data will be presented. Conclusion: The MTD was not established. Due to the incidence of TEAE judged related to Mipa and the preliminary activity observed, 15mg was selected as the highest dose to be tested in a fixed dose Q3W regimen. The study continues to enroll to further optimize Mipa dosing regimen and in dose escalation with gemcitabine. Citation Format: Brian Andrew Van Tine, Christopher T. Chen, Victor Moreno, Elizabeth J. Davis, Maria J. de Miguel, Antoine Italiano, Esma Saada-Bouzid, Mohammed Milhem, Claudia Valverde, Sant P. Chawla, Abdul Rafeh Naqash, Louise Carter, Robin Jones, Ilaria Conti, Joe Boni, Karin Havenith, Yvan LeBruchec, Serafino Pantano, Jean-Yves Blay. Phase 1b trial Mipasetamab Uzoptirine (ADCT-601-102) dose escalation in patients with advanced bone and soft tissue sarcomas [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 CT059.

Abstract CT188: A Phase I trial of AVA6000, a Fibroblast Activation Protein (FAP)-released and tumor microenvironment (TME)-targeted doxorubicin peptide drug conjugate in patients with FAP-positive solid tumors

Abstract Background: AVA6000 is a peptide drug conjugate, consisting of a peptide moiety that is specifically cleaved by FAP in the TME that is bound to doxorubicin. FAP is selectively overexpressed in many solid tumors. The peptide moiety linker (pre|CISIONTM) prevents cellular entry of doxorubicin unless cleaved by FAP, thus enabling targeted delivery of doxorubicin to tumors. Design: The safety, PK and preliminary efficacy of AVA6000 was studied in a first-in-man, multicenter dose escalation phase I trial. AVA6000 was administered intravenously q3w using a standard 3+3 design in patients with locally advanced or metastatic solid tumors reported to be FAP-positive. PK (AUC) based dosing was implemented to calculate maximum cycles of AVA6000 with the cumulative limit of 550 mg/m2. Results: Forty patients (median age 65 years, range 30-79), with median 3 prior lines of therapy (range, 0-7) received escalating AVA6000 doses from 80mg/m2 (51 mg/m2 doxorubicin; molar equivalent, 0.675) to 385 mg/m2 (260 mg/m2 doxorubicin equivalent). Tumor types included soft tissue sarcoma (30%), colorectal cancer (27.5%), pancreatic cancer (20%), cancers of the biliary tract (7.5%). The safety profile was favorable, the most frequent adverse events (any grade) being fatigue (50%), alopecia (42.5%), and nausea (32.5%), with rare grade 3-4 hematologic toxicities of neutropenia (7.5%), anemia, thrombocytopenia, and WBC decreased (5% each). Grade 3 non-hematologic toxicities included mucositis, fatigue and hematemesis (n=1 each). No grade 4 non-hematologic toxicities were reported. Two DLTs were observed of grade 2 cardiac failure (120 mg/m2; LVEF decrease 61 to 39%) and grade 4 neutropenia/thrombocytopenia (200 mg/m2). AVA6000 distributes rapidly with a t1/2 of 45 min. The Cmax of released doxorubicin was reduced as compared to standard dose doxorubicin (range 78-93% reduction) across dose cohorts. Tumor biopsy data demonstrate concentration of doxorubicin in the TME of mean 860 ng/gm (range 76-2310 ng/gm, n=9). In contrast, blood samples taken with the biopsy demonstrate a circulating free doxorubicin of 8.3 ng/ml (range 2.4-15.9), indicating concentration of doxorubicin in the tumor relative to plasma. Using RECISTv.1.1, one PR (-65%) with duration of 6 months was observed in a patient with undifferentiated pleomorphic sarcoma at 160 mg/m2, and a mixed response in a patient with angiosarcoma (SLD -22%) at 200 mg/m2. The disease control rate was 50%, at 12 wks. In each case, SD &amp;gt; 4 months or PR was associated with high FAP enzyme activity in the on-study tumor biopsy compared to observed disease progression as best response (n=6). Conclusions: AVA6000 delivers high concentration of doxorubicin to the TME relative to plasma which results in antitumor activity in tumors with high FAP activity. A q2w dose escalation arm is ongoing. Citation Format: Udai Banerji, Natalie Cook, Alan Anthoney, Ruth Plummer, William D. Tap, Jeffry T. Evans, Lee D. Cranmer, Christopher Plummer, Paul Loadman, Gezim Lahu, Huw S. Jones, Nelson Kinnersley, Fiona McLaughlin, Chris Twelves. A Phase I trial of AVA6000, a Fibroblast Activation Protein (FAP)-released and tumor microenvironment (TME)-targeted doxorubicin peptide drug conjugate in patients with FAP-positive solid tumors [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 CT188.

Abstract LB407: Propranolol may enhance long term survivorship in a subset of dogs with hemangiosarcoma when combined with doxorubicin chemotherapy

Abstract Angiosarcomas are rare (fewer than 300 cases each year), highly aggressive sarcomas of blood vessel-forming cells with an unfavorable prognosis. We and others have previously reported that propranolol, a beta adrenergic receptor antagonist commonly used to treat heart disease and anxiety, increased the overall survival of patients with advanced angiosarcoma when used alone or incorporated into chemotherapy regimens. Treatment of angiosarcoma has been hampered by the relative lack of suitable models to analyze molecular responses to treatment. To overcome this hurdle and understand the vulnerability of angiosarcoma to propranolol, we capitalized on the similar morphological and clinical characteristics between human angiosarcoma and canine hemangiosarcoma, which occurs in thousands of dogs each year. The objectives for the PRO-DOX clinical trial were to assess tolerability and clinical benefit of propranolol in dogs with hemangiosarcoma when given as an adjunct to chemotherapy. We conducted a phase I study using a continuous reassessment model with three dose cohorts (0.8, 1.0, and 1.3 mg/kg PO q 8 hrs) in dogs diagnosed with stage 1 or stage 2 splenic hemangiosarcoma. Following splenectomy, propranolol was onboarded using a dose escalation strategy over 12 days prior to the start of doxorubicin (30 mg/m2 intravenously every three weeks, five rounds). Twenty dogs were enrolled and distributed across the dose cohorts based on the study design. One dog in the highest cohort experienced acute hypotension after six months on propranolol, which resolved with dose reduction. Although a statistically significant survival benefit was not seen in this study when compared to historic controls, a subset of dogs (n=8 or 40%) exceeded the expected survival of 4-6 months. Notably, three dogs diagnosed at or below age five survived over two years. Gene expression analysis of tumors obtained from the short-, mid-, and long-term survivors revealed sets of genes associated with immune responses (e.g. lymphocyte activation, positive regulation of T cell activation), antigen processing, cell adhesion, and mitochondrial metabolism in the long-term survivor group. Our findings suggest that age (&amp;lt; 6 years) may predict a favorable outcome, and immune mediated responses differ between the short and long-term survivors. Ongoing experiments seek to define the specific molecular properties and immune responses contributing to these outcomes, with potential implications for human angiosarcoma. Citation Format: Erin B. Dickerson, Jeremy Chacón, Brian D. Husbands, Michael S. Henson, Jaime F. Modiano, Kathleen M. Stuebner, Amber Winter, Sara Pracht, Andrea Chehadeh, Kelly Bergsrud, Caitlin Feiock, Julia Medland, Heather Scavello, Pascale C. Salah, Jennifer Mahoney, Michael O. Childress, David R. Brown, Antonella Borgatti. Propranolol may enhance long term survivorship in a subset of dogs with hemangiosarcoma when combined with doxorubicin chemotherapy [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 LB407.

Abstract CT193: Phase 1 clinical trial evaluating the safety, tolerability, and immunogenicity of AST-021p, a novel cancer vaccine targeting HSP90-derived epitopes in advanced solid tumor patients (CornerStone-002)

Abstract Background: AST-021p is an "off-the-shelf" therapeutic cancer vaccine composed of two peptides, AST-021p4 and AST-021p5, derived from MHC class II-specific epitopes of Hunam HSP90 protein. Both peptides serve as antigenic determinants for HSP90 and act as a tumor-associated antigen (TAA) inducing activation of type 1 helper T cells (Th1). Th1 cell immunologically elicited by AST-021p secrete cytokines, including IFN-γ, and activate local antigen presenting cells (APC) enhancing cross priming at the tumor site. This immunological activity, through the mechanism of cross priming, sequentially leads to the activation of cytotoxic T cells and epitope spreading. In preclinical studies using the MMTV neu gene overexpressing mouse model, the administration of the HSP90 peptide vaccine, AST-021p, significantly inhibited tumor growth. Based on these scientific rationales, The first-in-human (FIH) study was conducted to evaluate the safety, tolerability, and immunogenicity of AST-021p in advanced solid tumor patients have no treatment option. Methods: Phase 1 study (CornerStone-002, NCT No.: 04864418) was conducted on patients with recurrent or metastatic solid tumors for whom applicable standard treatment options were unavailable (patient enrollment period: June 9, 2021, to June 14, 2023). Four-dose cohorts of AST-021p (Cohort 1: 1.2mg, Cohort 2: 2.4mg, Cohort 3: 3.6mg, Cohort 4: 4.8mg) received three vaccinations at 2-week intervals (Priming immunization) followed by boosting immunization with 4-week interval based on PI's discretion. Enrolling one patient initially in the lowest dose cohort, Cohort 1 (1.2mg), dose escalation occurred sequentially after confirming safety and tolerability. Subsequently, each dose cohort (Cohort 2: 2.4mg, Cohort 3: 3.6mg, Cohort 4: 4.8mg) enrolled six patients each for vaccination. Antigen-specific immune response was assessed by IFNγ ELISPOT using PBMCs from the subjects at baseline, 4 weeks, and 8 weeks. Results: During the study period, a total of 22 patients were enrolled (Cohort 1: 1, Cohort 2: 6, Cohort 3: 8, Cohort 4: 7). The median age of the patients was 66, with a gender distribution of 14 males and 8 females. Among the 22 patients, 20 completed the priming immunization with 3 vaccinations, and 7 of them proceeded with the boosting immunization. A total of 75 adverse events were reported in 21 patients (95.5%). Adverse drug reactions (ADRs) occurred in 15 patients (68.2%), accounting for 92 cases. The most common ADR was injection site reaction (ISR), observed in 15 patients (68.2%), with 35 cases and all reactions were graded as 1 or 2. Serious adverse events (SAEs), including gastrointestinal hemorrhage, vomiting, and aspiration, were observed in 3 patients (13.6%), totaling 3 cases. However, these events were unrelated to AST-021p. Conclusions: This study, as the first-in-human (FIH) administration of the AST-021p, demonstrated safety and tolerability across all four dose groups. Plus, optimal immunogenic dose (OID) and recommended phase 2 dose (RP2D) were confirmed based on AST-021p-specific immunogenicity and safety. Citation Format: Eun Joo Kang, Kyoungmin Lee, In Ho Kim, Ju Won Kim, Jwa Hoon Kim, Soohyeon Lee, Jiwon Lee, Kabsoo Shin, Sejun Park, Joori Kim, Hyun Won Shin, Kyong Hwa Park. Phase 1 clinical trial evaluating the safety, tolerability, and immunogenicity of AST-021p, a novel cancer vaccine targeting HSP90-derived epitopes in advanced solid tumor patients (CornerStone-002) [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 CT193.

Abstract LB236: Metabolically armed CD19 CAR-T cells for safe and effective treatment of relapsed or refractory CD19+ B cell hematological malignancies at extremely low doses

Abstract Background: The undeniable success of CD19 CAR-T cell therapy in managing relapsed or refractory (r/r) B-cell hematological malignancies, such as diffuse large B-cell lymphoma (DLBCL) and B-cell acute lymphoblastic leukemia (B-ALL), underscores its significance. Despite the favorable complete remission (CR) rates of around 50% for r/r DLBCL and up to 90% for r/r B-ALL, a notable challenge persists as more than half of patients experiencing CR after CD19 CAR-T cells treatment encounter relapse within a year, attributed to inadequate CAR-T persistence in both indications. Urgent attention is required to devise innovative strategies to overcome these challenges. Recently, we developed metabolically armed CD19 CAR-T cells expressing IL-10 can enhance OXPHOS metabolism, proliferation, and persistence of CAR-T cells in vivo. Significantly, these IL-10-expressing CAR-T cells trigger stem-like memory responses in various lymphoid organs, leading to robust tumor eradication and durable protection. Motivated by these promising findings, an open-label, single arm, investigator-initiated trial (IIT, ClinicalTrials.gov identifier: NCT05715606, NCT05747157) was conducted to assess the safety and efficacy of newly developed metabolically armed IL-10-expressing CD19 CAR-T (product name: Meta10-19 infusion) for treating patients with r/r DLBCL or r/r B-ALL. Method: From Feb 2023 to Dec 2023, this IIT clinical trial evaluated Meta10-19 infusion in adult patients with r/r DLBCL or r/r B-ALL. The patients were recruited and treated at the First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China. Patients in 3 dose cohorts (2.0 × 104, 5.0 × 104, or 1.0 × 105 CAR-T cells/kg, corresponding to 1%, 2.5%, or 5% doses of commercialized CAR-T infusion) underwent lymphodepleting chemotherapy with cyclophosphamide and fludarabine before Meta10-19 infusion. The primary endpoint was the incidence of dose-limiting toxicities. The secondary endpoint was the response and survival. Results: The treatment with Meta10-19 infusion has successfully induced CR in all 12 cases of r/r DLBCL (n=6) or r/r B-ALL (n=6), as evaluated by PET-CT scan, NMR spectroscopy or minimal residual disease assessment of bone marrow. No server cytokine storm syndrome or neurotoxicity was observed. All treated patients achieved CR at 3 months post treatment, with the first patient maintaining continuous remission up to 9 months until now. Notably, these metabolically armed CD19 CAR-T cells demonstrated efficacy even for patients with bulky mass (≥7.5 cm) of DLBCL at extremely low infusion dose (1~5% doses of commercialized CAR-T). Conclusion: Preliminary findings suggest that Meta10-19 infusion exhibits promising breakthrough efficacy and safety profile, and active enrollment is ongoing to validate the initial results. Citation Format: Yugang Guo, Qianwen Xu, Lei Xue, Erling Chen, Chonglin Liu, Min Gao, Youjia Li, Jingjing Ren, Jinping Li, Li Tang, Xingbing Wang. Metabolically armed CD19 CAR-T cells for safe and effective treatment of relapsed or refractory CD19+ B cell hematological malignancies at extremely low doses [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 LB236.