Positive Tumors Research Articles

Phase 1 study of ZV0203, a first in class pertuzumab ADC, in patients with HER2 positive advanced solid tumors.

e15004 Background: ZV0203, a first in class (FIC) pertuzumab antibody-drug conjugate (ADC), targets HER2 positive tumor cells with tubulin inhibitor DUO5 as its payload via a stable and protease-cleavable valine-citrulline linker. In preclinical studies, ZV0203 demonstrated superior antitumor activity compared to Kadcyla in multiple tumor cell line xenograft models with no noticeable toxicity. GLP toxicity studies indicated that ZV0203 was well tolerated with an estimated therapeutic index of 35. Methods: This was an open-label, multicenter, phase 1, dose-escalation study in patients (pts) with HER2+ advanced solid tumors. Primary objectives were safety, tolerability and RP2D. Secondary objectives included PK, immunogenicity and preliminary clinical efficacy. ZV0203 was administered intravenously Q3W on a 21-day cycle. An accelerated titration design was used for the 0.3 and 0.6 mg/kg doses, followed by a 3+3 design for 1.2, 1.8, 2.7 and 3.6 mg/kg dose levels. Results: As of January 18, 2024, 15 pts with solid tumors (breast [11], colorectal [2], gastric [1], lung [1]) were enrolled across doses of 0.3-3.6 mg/kg with a median age of 52 years old (range 35-65), of which 9 pts received prior HER2-targeted therapy (trastuzumab ± pertuzumab) and 14 pts completed 21-day DLT assessment (0.3 mg/kg and 0.6 mg/kg [1 each], 1.2 mg/kg, 1.8 mg/kg, 2.7 mg/kg and 3.6mg/kg [3 each]) with no DLT incidence. Treatment-related adverse events (TRAE) occurred in 14 (93.3%) pts. The most frequent TRAEs were corneal epitheliopathy [9], elevated liver enzymes [6], dry eyes [6], neutropenia [4], anemia [4], leukopenia [3], and proteinuria [3], and most were grade 1-2 in severity. 5 pts experienced grade 3 TRAEs: lymphocytopenia (1.8mg/kg [1]) , corneal epitheliopathy (3.6 mg/kg [1]) and blurred vision (2.7 mg/kg [2], 3.6 mg/kg [1]), which were manageable during treatment. No unexpected safety signals were reported. TRAEs led to 13.3% (2/15) treatment discontinuation. Among 14 pts evaluated, 5 pts achieved a best tumor response of PR; 4 pts had SD; 1 pt had Non-CR/Non-PD per RECIST v1.1. Thus, disease control rate was 71.4% (10/14). PK results demonstrated that the PK profile of total antibody was similar to that of ZV0203 ADC, whose systematic exposure increased in a dose-dependent manner and remained stable after repeated administration. Concentration of DUO5 remained scarce, suggesting good stability of ZV0203. Conclusions: ZV0203 was well tolerated and showed clinically encouraging anti-tumor activity in heavily pretreated pts with HER2 positive cancer. Clinical trial information: NCT05423977 .

A phase II randomized control trial of triapine plus lutetium 177 DOTATATE versus lutetium 177 DOTATATE alone for well-differentiated somatostatin receptor-positive neuroendocrine tumors.

TPS4202 Background: Radiolabeled somatostatin analogues provide a means of delivering targeted radiation with a high therapeutic index to NETs that express somatostatin receptors (SSTRs). Radiolabeled somatostatin analogue Lutetium 177 DOTATATE (Lutathera) is a beta-emitting radionuclide, FDA approved for use in SSTR positive gastroenteropancreatic neuroendocrine tumors (GEPNETS) in the US based on the NETTER-1 Phase III trial. Despite favorable PFS and safety profile, the drug has limited cytoreductive capability with a 14% ORR. Peptide receptor radionuclide therapy (PRRT) also doesn’t seem to be very effective in treating peritoneal disease. We hypothesize that addition of an effective radiation sensitizer could help improve antitumor activity of Lutathera. Radiation is a potent inducer of DNA double-strand breaks, and ribonucleotide reductase (RNR) is the rate-limiting enzyme in the synthesis and repair of DNA, making RNR-targeted therapy a rationale therapeutic strategy for radiosensitization. ETCTN 10388 (NCT04234568) evaluated safety and efficacy of the combination of lutetium 177 DOTATATE, a beta-emitting radionuclide in combination with triapine, a ribonucleotide reductase (RNR) inhibitor. The combination of triapine and Lu-177 DOTATATE was safe with preliminary efficacy signals. Methods: This study is an investigator initiated, NCI sponsored, multicenter randomized phase 2 trial of triapine and lutetium Lu 177 DOTATATE in well-differentiated somatostatin receptor-positive neuroendocrine tumor. A total of 94 patients will be equally randomized to either Lu-177 dotatate or Triapine + Lu-177 dotatate arm. The study will be open through the NCI ETCTN (National Cancer Institute Experimental Therapeutics Clinical Trials Network) program. Triapine will be administered orally from D1-14 with each dose of PRRT [200 mCi]. Primary endpoint is to evaluate overall response rate (ORR). Secondary endpoint is to evaluate median PFS. We are also evaluating triapine PK, plasma deoxyribonucleosides, circulating DNA and plasma hPG80, a novel blood based diagnostic biomarker. Clinical trial information: 05724108.

Preliminary results of phase I/II study to evaluate safety and efficacy of combination pucotenlimab with epidermal growth factor receptor-ADC (EGFR-ADC) MRG003 in patients with EGFR positive solid tumors.

6013 Background: Pucotenlimab (HX008) is a recombinant humanized PD-1 inhibitor approved for marketing in China, and MRG003 is an EGFR-ADC which has shown promising anti-tumor activity in squamous cell carcinoma of the head and neck (SCCHN) and nasopharyngeal carcinoma (NPC) in multiple clinical studies. In the preclinical studies, the combination of them has demonstrated a synergistic antitumor effect. This study was aimed to assess the safety and efficacy of the combination therapy in patients (pts) with locally advanced or metastatic solid tumors known to express EGFR. Methods: In this Phase I/II dose escalation and expansion study, eligible pts were treated with 3.0 mg/kg HX008 combined with MRG003 every 3 weeks, with an escalated dosing ranging from 1.5 mg/kg to 2.3 mg/kg. The primary endpoints were maximum tolerated dose (MTD), recommended Phase II dose (RP2D) of combination and objective response rate (ORR). Secondary endpoints included duration of response (DOR), disease control rate (DCR), and progression-free survival (PFS). Results: As of 30 January 2024 (cut-off date), 33 pts (9 NPC, 1 SCCHN and 3 other solid tumors pts in Phase I, 14 NPC and 6 SCCHN pts in Phase II) were enrolled in this study with a median age of 52 (31,65), and 25 pts (76%) were male. 11 (33%) pts were ECOG PS 0. The most commonly reported treatment-related adverse events (TRAEs) included pruritus (46%), rash (33%), AST increased (30%), anemia (30%). Grade 3-4 TRAEs occurred in 4 pts (12%), and mainly was white blood cell count decreased (9%) and hypokalemia (6%). The only DLT event occurred in the 2.3mg/kg dose group, and the RP2D of MRG003 determined was 2.0mg/kg by SMC. Out of the 27 evaluable pts, 17 pts achieved PR and 7 pts achieved SD, thus the ORR and DCR were 63.0% (95%CI: 42.4, 80.6) and 88.9% (95%CI: 70.8, 97.7), respectively. In the Phase II, among 9 evaluable EGFR-positive NPC pts progression after first-line treatment of PD-1 plus platinum-based chemotherapy, 2 CR, 5 PR and 2 SD were observed, ORR and DCR were 77.8% (95%CI:40.0, 97.2) and 100% (95%CI:66.4, 100), respectively. Five evaluable systemic treatment naïve SCCHN pts with EGFR-positive, 3 PR and 1 SD were observed, ORR and DCR were 60% (95%CI:14.7, 94.7) and 80% (95%CI:28.4, 99.5), respectively. The DOR and PFS in the study were immature. The longest patient treated has had a DOR for more than 17 months and still ongoing. Conclusions: The Phase I/II study pts treated with HX008 in combination with MRG003 demonstrated good tolerability and encouraging antitumor activity in NPC and SCCHN, especially in PD-1 treatment failed NPC pts. The Phase II study is currently ongoing. Research Sponsor: Shanghai Miracogen Inc. Clinical trial information: NCT05688605.

Quality of life (QoL) benefits following 177Lu-DOTATATE therapy in patients (pts) with 68Ga-DOTATATE PET positive primary site agnostic neuroendocrine tumors (NET).

e16291 Background: The QoL experience during the 1st year of follow up for 68Ga-DOTATATE PET positive primary site agnostic pts with progressive metastatic NET enrolled in a prospective single arm clinical trial of 177Lu-DOTATATE therapy (OZM 067) is described here. Methods: Pts with progressive NET, Ki67 Index < 30%, adequate organ function & ECOG £2 were eligible. Only pts demonstrating positive disease (Krenning score 3-4) on 68Ga-DOTATATE PET were eligible to proceed to 177Lu-DOTATATE therapy (4 cycles at 8- to 12- week intervals. Primary outcome was progression free survival (PFS) at 12 mths. QoL (EORTC QLQ 30 and GINET21) at baseline, 6, 12, 18, 24, 30 months were recorded. Summary scores at time point of interest, and their change from baseline were estimated using a mixed model repeated measure, with baseline assessment included in the model as covariate. Data were normalized with a range of 0-100. A positive change score for Global Summary Status, Functioning Domains, and a negative change score for Symptom Scales and Items represent improvement. A ≥5 point change score is used as a threshold for Minimal Clinically Important Difference (MCID). Results: 195 pts were enrolled. 13 pts were 68Ga-DOTATATE PET negative while 5 pts withdrew consent. 177 pts received at least one dose of 177Lu-DOTATATE. All pts enrolled were eligible for a minimum of 12 mths follow up at time of data lock. The primary site was GEPNET in 143 (81%) and non GEPNET in 34 (19%). At 12 mths, the median follow-up was 33 (range 3-71) mths. PFS and OS were 81 (95% CI: 75-86)% and 92 (87-95)% respectively. QoL data at the following timepoints baseline, 6 & 12 (±2) mths were available in 174,128 & 111 pts respectively. The top three symptoms captured in EORTC QLQ 30 was Fatigue (32.5 SD 23.8) , Insomnia (26.7 SD 28.1) and Diarrhea (22.1 SD 29.4). At 12 mths, an improvement in mean score of ≥MCID in Global Health status (GHS) (+5.4), Role Fc Scale (+7,1), Social Fc Scale (+8.7) and multiple symptoms (Fatigue, Pain, Appetite, Constipation, Diarrhea, Financial Difficulties), Sexual fc, Social, Body image (Table 1) were captured. Conclusions: Patients with primary site agnostic 68Ga-DOTATATE PET positive NET experienced improvement in multiple quality of life domains including multiple symptoms post 177Lu-DOTATATE at 12 mths. Sexual fc and body image had the largest improvement. Clinical trial information: NCT02743741 . [Table: see text]

Open-label, dose-escalation phase 1a study of SPH5030, a tyrosine kinase inhibitor (TKI) targeting HER2, in patients with HER2 positive advanced solid tumors.

Open-label, dose-escalation phase 1a study of SPH5030, a tyrosine kinase inhibitor (TKI) targeting HER2, in patients with HER2 positive advanced solid tumors.

Binary oncolytic adenovirus in combination with HER2-specific autologous CAR VST for treatment of advanced HER2-positive solid tumors (VISTA).

TPS2679 Background: Urgent therapies are needed for patients with refractory Human Epidermal Growth Factor Receptor 2 (HER2) positive solid malignancies. Our group has previously shown potent antitumor effect of a binary oncolytic/helper-dependent adenovirus (CAdVEC) with dual expression of IL-12 and PD-L1 blocker. Initial preclinical and clinical studies with direct tumor injection of CAdVEC has shown it to be safe and result in increased infiltration of CD8 T cells into the tumor microenvironment, with antitumor effect on locoregional and distant metastatic sites.1 Based on these results, we describe an ongoing study with addition of HER2-specific autologous chimeric antigen receptor (CAR)-T cell therapy to CAdVEC. Methods: This is a single arm, dose escalation phase I clinical trial guided by Bayesian Optimal Interval Design (BOIN) for patients with advanced HER2 positive solid tumors. Patients who are deemed unsuitable for curative treatments and progressed after at least one standard first line therapy are eligible. HER2 positivity is determined by IHC and defined as ≥2+. Patients are required to have at least one tumor site appropriate for intratumor injection and radiographically measurable disease per RECIST v1.1. Patients with autoimmune disease requiring systemic corticosteroids greater than 10mg/day and those with active/untreated CNS metastasis are excluded. Patients will receive increasing doses of CAdVEC intratumor injection alone (first two dose levels) or in combination with HER2 specific autologous CAR-T cells (dose levels 3-7). A total of 45 patients are planned. The primary endpoint of the study is to evaluate safety and maximum tolerated dose as assessed by incidence of dose limiting toxicities (DLT) of CAdVEC intratumor injection in combination with HER2-specific autologous CAR T cells. Secondary endpoints include anti-tumor activity of the combination measured by overall response rate (ORR), disease control rate (DCR), median progression free survival (PFS) and median overall survival (OS). Exploratory endpoints include assessing the immunogenicity of combination therapy by determining the impact of treatment on cellular and humoral immunity, as well as assessing long-term persistence and functional status of HER2 CAR T-cells. Correlative analysis of levels of adenovirus antibodies with clinical outcomes and immunological findings are also planned. This study is currently enrolling. 1. Wang D, Porter CE, Lim B, et al: Science Advances 9, 2023. Clinical trial information: NCT03740256 .

The design, preclinical study and phase I dose escalation plan of a HER2 targeted immunoliposome (HF-K1) for HER2 low solid tumor treatment.

3035 Background: Doxorubicin liposome formulations are being used extensively in the clinic in anthracycline chemotherapy with reduced cardiotoxicity. However, they did not improve clinical outcome because the cancer cell uptake of PEG-coated liposomes is poor. So, the concept of coating antibodies on the liposome surface was initiated and they were named immunoliposomes. There have been numerous studies conducted world-wide for the development of immunoliposomes but none have progressed to late-stage development. Our work draws on the experiences of these prior studies with a new perspective. Since the mechanism of immunoliposomes is similar to those of ADCs, we sought to compare immunoliposomes with ADCs containing the same cancer cell binding domain, for target cell binding capability, binding affinity as well as in vivo distribution, tumor tissue accumulation, and anti-tumor activities. The lessons learned from the success of many ADC products may be applicable to the development of immunoliposomes. Methods: The antibody to liposome ratio (ALR) and the drug to lipid ratio (DLR) of the immunoliposomes were selected by in vitro and in vivo anti-cancer activity screening. Cell lines with different HER2 expression levels were used to study immunoliposome binding, cell uptake, drug delivery and cytotoxicity. PK, drug distribution, efficacy and toxicities studies were conducted in respective CDX and PDX mice and non-rodent models. Based on these studies, a phase I dose escalation study plan was designed and the study is now ongoing. Results: HF-K1 was designed to have an average of 10 anti-HER2 Fab on each liposome surface and approximately 2300 doxorubicin molecules inside. The equivalent drug to antibody ratio (DAR) is 230. HF-K1 can bind to cancer cells with different levels of HER2 expression with similar kinetics and induces cells death at IC50s of 0.35-6.46 μg/ml Fab concentration. It has a long circulation behavior and enhanced permeability and retention (EPR) in tumor tissues. The clearance T1/2 of HF-K1 in mice and monkey is 12.78 h and 47.12 h, respectively. Evaluation of HF-K1 activity in vivo showed significant tumor growth inhibition >95% at the equivalent antibody dose of 3.6 mg/kg in various mouse tumor models including HER2 low and HER2 very low (HER2-). Similar activities were shown by ADCs including T-DM1 and DS-8201a at about 10 mg/kg. Conclusions: The encouraging preclinical data supported a clinical trial starting with dose escalation at equivalent antibody doses of 0.72 mg/m2, 2.16 mg/m2, 5.4 mg/m2, 10.8 mg/m2, 16.2 mg/m2, and 21.6 mg/m2. The study is ongoing to determine the safety, tolerability, PK, and preliminary antitumor efficacy in participants with HER2 positive or HER2 low expression advanced solid tumors (NCT05861895). Clinical trial information: NCT05861895 .

9MW2821, a nectin-4 antibody-drug conjugate (ADC), in patients with advanced solid tumor: Results from a phase 1/2a study.

3013 Background: 9MW2821 is a monoclonal ADC that delivers monomethyl auristatin E to cells expressing Nectin-4. Nectin-4 is an adhesion molecule that highly expressed in variety of solid tumors, especially urothelial cancer (UC), cervical cancer (CC), esophageal cancer (EC) and breast cancer. Here we report the updated safety and efficacy data of 9MW2821. Methods: 9MW2821 was administered by intravenous infusion at doses of 0.33-1.5mg/kg on days 1, 8 and 15 of each 28-day cycle. The study included dose escalation, dose expansion and cohort expansion period which included UC, CC, EC, triple negative breast cancer (TNBC) and other Nectin-4 positive solid tumors that progressed after ≥1 systemic treatments (Tx). Primary objectives were assessment of safety and preliminary efficacy. Results: As of Jan 15, 2024, 260 patients (pts) were enrolled with doses ranging from 0.33 to 1.5mg/kg. Only 1 out of 6 pts in 1.5mg/kg group had dose limiting toxicity (grade 4 neutropenia lasted more than 5 days). The maximum tolerated dose was not reached up to 1.5mg/kg and the RP2D was selected as 1.25mg/kg for tolerance. 240 pts were enrolled at dose of 1.25mg/kg. The most common TRAEs of 1.25mg/kg dose group (≥20%, all grade/≥5%, ≥G3) were white blood cell (WBC) count decreased (50.8%, 23.3%), neutrophil count decreased (46.3%, 27.9%), anemia (43.8%, 8.3%), aspartate aminotransferase increased (42.1%, 2.9%), alanine aminotransferase increased (35.4%, 2.1%), asthenia (32.1%, 2.9%), rash (30.0%, 5.0%), decreased appetite (28.8%, 1.3%), nausea (26.7%, 0%), hyperglycemia (25.4%, 2.1%), platelet count decreased (24.2%, 4.6%), alopecia (24.2%, 0%), hypoaesthesia (22.5%, 1.7%), constipation (21.3%, 0%), vomiting (20.9%, 1.3%), hypertriglyceridemia (20.4%, 2.1%), gamma-glutamyltransferase increased (15.8%, 5.4%). Among 190 pts treated with 9MW2821 at 1.25mg/kg or above and reached tumor assessment, objective response rate (ORR) and disease control rate (DCR) was 35.3% and 78.4%, respectively. 37 UC pts, 45 CC pts, 27 EC pts and 16 TNBC pts were enrolled at 1.25mg/kg and evaluable for tumor assessment. Median prior lines of Tx were 2 (range, 1-4). All UC, 51% CC and 93% EC pts progressed after platinum-based chemotherapy and immune checkpoint inhibitors, respectively. Objective responses were also observed in pts with other solid tumor types. Conclusions: The data indicated encouraging efficacy of 9MW2821 in advanced UC, CC, EC and TNBC. 9MW2821 is the first Nectin-4 targeting ADC showed antitumor activity in patients with CC, EC and TNBC. The safety profile showed adequate tolerability. Clinical trial information: NCT05216965 . [Table: see text]

Prevalence and dynamics of circulating tumor DNA (ctDNA) among patients (pts) with HER2+ breast cancer (BC) receiving neoadjuvant paclitaxel/trastuzumab/pertuzumab (THP) in the DAPHNe trial.

588 Background: Neoadjuvant THP may become a new standard for pts with early stage HER2+ BC pending results of large ongoing trials. Although ctDNA persistence in the (neo)adjuvant setting is associated with elevated risk of distant recurrence, the prevalence and dynamics of ctDNA in HER2+ BC are unknown. Methods: On the single-arm phase II DAPHNe trial, pts with stage II-III HER2+ BC received 12 weeks of neoadjuvant THP, followed by surgery and adjuvant systemic therapy (tx) per physicians’ discretion (with no further chemotherapy in case of pCR). Plasma samples were prospectively collected at 4 timepoints: baseline (BL), pre-operatively (pre-op), immediate post-operatively (post-op), and during the final 3 mos of adjuvant HER2-directed tx. ctDNA was measured using NeXT Personal, a tumor-informed assay based on whole-genome sequencing of tumor/normal samples to detect and quantify minimal residual disease (MRD). We assessed the association of MRD with residual cancer burden (RCB) and long-term outcomes. Results: Of 98 pts enrolled in DAPHNe, 50 had at least one plasma sample sequenced with NeXT Personal. Of these 50 pts, the median age was 50 yrs, 92% had clinical stage II and 64% had hormone-receptor positive (HR+) tumors. RCB scores were: RCB 0 (33/50 pts, 66%), RCB I (2/50 pts, 4%), RCB II (14/50 pts, 28%), RCB III (1/50 pts, 2%). With 50 mos median follow-up, there have been no breast cancer recurrences. ctDNA was detected (ctDNA+) at BL in 42/49 pts (92%) (median detected level 210 parts per million (PPM), broad detection range of 36,978 down to 3 PPM, and 34% of detected pts had ctDNA level <100 PPM). All pts with T3/T4 tumors or positive nodes had BL ctDNA+, whereas 91% and 85% of pts with T1/T2 or node-negative tumors, respectively, had BL ctDNA+. Most pts cleared MRD after THP. Rates of ctDNA detection at post-BL timepoints were: 2/49 pts (4%) at pre-op; 2/48 pts (4%) at post-op; and 1/34 pts (3%) at late adjuvant times. Statistical comparison of pts who cleared vs did not clear ctDNA during neoadjuvant THP was not possible given the high rate of ctDNA positivity at BL and the high rate of negativity pre-op. Clinical vignettes of the 5 pts with detectable MRD at any post-BL timepoint are shown (Table). MRD data from additional pts will be presented. Conclusions: In this population of moderate risk (mostly stage II) HER2+ BC pts, 92% were ctDNA+ at BL. Neoadjuvant THP was very effective at clearing MRD, regardless of whether there was residual disease in the breast/nodes or not, consistent with the absence of any BC recurrence in the cohort to date. Clinical trial information: NCT03716180 . [Table: see text]

Trends in the management of small HER2-positive breast cancers.

e12523 Background: Small HER2 positive breast cancers have not been well studied in randomized trials. The treatment landscape for this population aims to optimize efficacy while minimizing potential over-treatment and associated toxicities. Due to the potential for post-neoadjuvant therapy optimization, use of neoadjuvant systemic therapy (NAT) increased in recent years. However, this approach can often lead to overtreatment of patients with small tumors. This study aims to evaluate recent trends in treatment patterns of patients with T1 HER2 positive tumors. Methods: Patients diagnosed with HER2 positive, T1, any N, breast cancer treated at a single institution from January 2018 to December 2022 were included. Clinicopathological data, treatment data, and survival data were collected and analyzed. Results: 326 patients were included. Mean age was 62 (±12.2) years. T category included 3 (0.9%) cT0, 17 (5.2%) cTmi, 28 (8.6%) cT1a, 94 (28.8%) cT1b, 178 (54.6%) cT1c tumors, and 6 patients (1.8%) had clinical T1 stage without further specification. 41 patients (12.6%) had cN+ disease and 243 (74.5%) were hormone receptor positive. Systemic therapy data was available for 288 patients; 7 (2.4%) received Herceptin monotherapy, 105 (36.5%) Taxol + Herceptin, 41 (14.2%) Taxol + Carboplatin + Herceptin, and 74 (25.7%) Taxol + Carboplatin + Herceptin + Pertuzumab (TCHP), 12 (4.2%) other. 49 patients (17%) did not receive any systemic therapy. 58 patients (17.8%) were treated with NAT and a pathologic complete response rate was noted in 39 patients (67.2%) undergoing NAT. Overall, in patients who received systemic therapy, NAT increased from 2018 (17.6%) to 2021 (37.5%) and decreased in 2022 (23.5%). Similar patterns were observed in patients with T1a/b (2021: 17.4%; 2022: 0%), as well as T1c (2021: 51.4%; 2022: 36.4%). TCHP was the most commonly administered NAT regimen (86.2%). Discontinuation or dose reduction occurred in a total of 57 patients (18.8%). Conclusions: The primary treatment for T1 HER2 positive breast cancers is surgery with adjuvant HER2 targeted therapy in combination with chemotherapy. Although NAT witnessed an upward trend from 2018 to its peak in 2021, its utilization declined again in 2022. A balance between the most effective treatment and minimizing toxicities should be ensured.

A retrospective, single-center study comparing two neoadjuvant protocols for patients with HER2-positive breast cancer.

e12623 Background: Neoadjuvant treatment is common in Stage 2+3 HER2 positive tumors. Cytotoxic and anti-HER2 drug combinations are used. Pathological complete response (pCR) correlates with improved survival and decreased risk of relapse. Trastuzumab may cause temporarily congestive heart failure (CHF) while anthracyclines may cause irreversible CHF. Current guidelines advise non-anthracycline based regimens. Here, we compare the efficacy and toxicity of these two regimens. Methods: Retrospective data were collected on 179 patients with clinical stage II-III, who received neoadjuvant treatment with either 6 cycles of DCHP (Docetaxel, Carboplatin AUC6 [53.2% received AUC5], Trastuzumab, Pertuzumab) or ACTHP (doxorubicin, cyclophosphamide followed by weekly Paclitaxel combined with HP). According to pCR response post surgery, adjuvant HP or TDM-1 were given to go complete one year of treatment. Efficacy Indices of pCR were evaluated in both cohorts and according to HER2 IHC staining (3+ or 2+ FISH positive), hormone receptor (HR) and nodal status. Toxicity indices were reductions in left ventricular ejection fraction (LVEF), dose reductions, hospitalizations and febrile neutropenia. Results: Between 9.2017 and 6.2022, 106 patients received ACTHP and 73 received DCHP. Median age at diagnosis, HR status, HER2 IHC (2+FISHpos or 3+) and nodal status were balanced. PCR occurred in 63.1% of all patients, numerically higher in the ACTHP group at 67.0% vs. 57.5% in the DCPH group (p=0.129). Symptomatic LVEF decrease (>10% or LVEF≤50%) was observed in 6.6% of the ACTHP group vs. 0% in the DCHP group (p<0.001). Hospitalization rates were similar (14%). Dose reductions occurred more often in the DCHP regimen vs ACTHP (54.8% vs 24.5% respectively) (p<0.00001) mostly due to asthenia and diarrhea. Febrile neutropenia was slightly higher in the ACTHP group but not statistically significant. Conclusions: In this study, pCR rates were numerically better in the ACTHP regimen vs. DCHP, though not statistically significant. Dose reductions were more common in the DCHP but had less cardiotoxicity. pCR rates were relatively low in both regimens where Her-2 +2, FISH pos. This study shows that the DCHP is a safe and effective alternative to anthracycline based chemotherapy though total dosage may be an important factor in the level of pCR.[Table: see text]

Interaction between VEGF-A and immune checkpoint targets in triple-negative breast cancer and mechanisms of immune evasion and tumor progression.

1096 Background: Immune checkpoint inhibitors (ICIs) have revolutionized the treatment triple negative breast cancer (TNBC). However, not all patients with TNBC benefit from the addition of ICIs due to factors such as intrinsic and acquired resistance to ICIs, and complex interplay between tumor and immune cells in the tumor microenvironment (TME). Vascular endothelial growth factor (VEGF) promotes angiogenesis and potentially modulates tumor immune evasion. A phase I clinical trial has shown that a bispecific antibody to VEGF-A and PD-L1 produces encouraging tumor responses in advanced TNBC. In this study, we investigated the interaction between VEGF and various immune gene expression signatures including PD-L1 in a real-world breast cancer patient population. Methods: Comprehensive immune profiling, including the RNA-seq based gene expression assessment of 395 immune-associated genes, was performed on 120 formalin-fixed paraffin-embedded breast cancer samples. PD-L1 expression (Combined Positive Score, CPS ≥ 10%) was measured by immunohistochemistry (IHC; 22C3). Clinicopathologic variables were collected. Statistical associations between quantitative biomarkers, including 28 immune checkpoint genes, were calculated using Pearson correlations (r), and comparisons of quantitative biomarkers between groups were performed using the proportions test. For statistical significance, p<0.05 was required. Results: The study cohort included 29 patients (24.2%) with TNBC and 91 (75.2%) with non-TNBC (including ER+/HER2- and HER2+). Most patients had metastatic tumors (n=92, 76.7%) and invasive ductal carcinoma (n=83, 69.2%). Among the TNBC group, 21 patients had PD-L1 positive tumors (72.4%), defined by CPS ≥ 10.In non-TNBC, VEGF has significant, though weak (r<0.35) correlations with the expression of three checkpoint genes: AKT1 (r=0.35, p=0.00063), ICOS (r=0.34, p=0.00099), and TIM3 (r=0.29, p=0.0061). In TNBC, VEGF has significant, strong (r>0.47) correlations with the expression of three other checkpoint genes: PD-1 (r=0.47, p=0.0094), PD-L1 (r=0.57, p=0.0012), and PIK3CA (r=0.6, p=0.00051) However, in TNBC, VEGF gene expression does not have a statistical association with PD-L1 IHC (CPS ≥/< 10 (p=0.9)). Conclusions: Our findings suggest that there is an interplay between angiogenesis and an immunosuppressive tumor immune microenvironment in TNBC to a greater degree than in non-TNBCs. This supports the notion that angiogenesis mediators such as VEGF-A may enhance the expression of immunosuppressive checkpoint molecules, leading to immune evasion and tumor progression. Combination treatments of ICIs, especially anti-PD-1 therapy, with VEGF antibodies may be promising approaches to enhance the immune responses in TNBC, especially in tumors with CPS<10, where the current frontline treatment is cytotoxic chemotherapy.

Preclinical studies of an innovative 5T4-ADC ACR246 with the potential to better treat 5T4-positive solid tumors.

e15005 Background: 5T4 oncofetal antigen shows limited expression in normal adult tissues but highly expressed by many different cancers. It drives spread of cancer cells through epithelial mesenchymal transition (EMT), potentiation of CXCL12/CXCR4 chemotaxis and favoring non-canonical Wnt pathway, leading to poor prognosis of cancer patients. Besides, 5T4 has a highly efficient endocytosis ability which enables it to be an ideal target for the development of ADC drugs. A handful of 5T4-targeted ADCs have been evaluated in early phase clinical trials for several years showing only preliminary anti-tumor activity. However, uncertainty of their safety profiles has also raised concerns due to high toxic payloads, MMAF and duocarmycin, being used. Thus, additional approaches to this target with the potential of improved efficacy and reduced toxicity are needed urgently. ACR246, an innovative 5T4-targeted ADC consisting of specific humanized monoclonal antibody site-specifically conjugated with a cell penetrating and moderate toxic payload (DNA topoisomerase I inhibitor, D2102) that has a robust bystander effect through a stable and cleavable linker, with a drug-to-antibody ratio (DAR) of 8, was designed to improve the safety and efficacy in treating tumor patients. Methods: The pharmacologic profiles of ACR246 were assessed in vitro and in vivo including efficacy, pharmacokinetics-pharmacodynamics (PK-PD), safety, and tissue distribution, in 5T4-positive cell lines, cell-derived xenograft (CDX) models and cynomolgus monkeys. Results: ACR246 bound specifically to 5T4 and was internalized into tumor cells followed by D2102 release, which induced DNA damage, cell cycle arrest and apoptosis in 5T4 positive tumor cells in vitro. In vivo low systemic exposure and tumor-specific accumulation of D2102 rendered ACR246 superior efficacy and safety property. Accordingly, ACR246 exhibited robust in vivo anti-tumor activity across various types of 5T4 positive CDX models in a dose-dependent manner, with DNA damage induced by the accumulated D2102 in tumor tissue. GLP toxicity studies indicated that ACR246 was well tolerated in cynomolgus monkeys. The estimated therapeutic index was 24. Conclusions: The overall preclinical profile marks ACR246 has the potential to become the best in class (BIC) 5T4-ADC, showing more favorable benefit-risk ratio in clinic.

TROCEPT: An oncolytic virus platform engineered for αvß6 integrin targeted tumor-localised expression of an immune checkpoint inhibitor following intravenous delivery.

e14579 Background: TROCEPT is a novel tumor-selective replicating, oncolytic adenovirus type 5 (Ad5) rationally engineered to remove all natural tissue tropisms. This engineering addresses the main limitation of other viral therapies which infect normal tissues and are rapidly removed by the liver and are therefore limited to local delivery. TROCEPT has been further engineered to specifically bind to αvβ6 integrin which is expressed at high frequency in the majority of epithelial cancers, so that following intravenous delivery the virus targets tumor tissue where it replicates and amplifies. In addition, the TROCEPT platform encodes transgenes which enables in-tumor production of powerful therapeutic drugs. The lead programme, TROCEPT-01, encodes a fully human, full length immune checkpoint inhibitor (ICI) antibody. TROCEPT-01 is currently undergoing IND-enabling studies and is expected to enter First in Human studies in 2024 in multiple solid tumor indications. Methods: Proof of concept studies, both in vitro and in vivo, to demonstrate TROCEPT-01’s tumor selectivity and toxicity profile have been performed. Results: In vitro experiments demonstrate that viral replication, transgene expression and oncolytic cell death following infection with TROCEPT-01 is highly selective for αvβ6 integrin positive tumor cells compared to a panel of normal human primary cells. Intravenous delivery in in vivo SKOV3 ovarian human tumor xenograft mouse models demonstrate virus delivery, replication, and transgene expression in the tumor. In comparison to the parental Ad5 virus, the engineering of TROCEPT-01 leads to more viral delivery to the tumour, less delivery to normal tissue including liver, reduced markers of liver toxicity and reduced inflammatory cytokine release, all of which validate the tumour selectivity and safety profile of the virus. Conclusions: We have demonstrated that TROCEPT engineering enables highly selective tumor targeting and significant tumor exposure following intravenous delivery. TROCEPT-01’s in-tumor selective expression of ICIs enables high local drug concentration in the tumor, potentially reducing systemic toxicity and increasing efficacy. TROCEPT-01 is currently undergoing IND-enabling studies and is expected to enter First in Human studies in 2024 in multiple solid tumor indications.

Receptor expression testing of the synchronous axillary nodal metastasis in early-stage breast cancer: Comparison of primary tumor and its draining nodes.

e12542 Background: Early stage (Stage I-III) human epidermal receptor -2 (HER2) positive and triple negative breast cancers (TNBC) tend to behave more aggressively than hormone positive breast cancers with higher and earlier incidences of recurrences. Oftentimes, testing for receptor subtypes is done only on the primary tumor and not on the synchronous axillary metastasis, with the assumption that the axillary metastasis is congruous to the primary lesion. Current guidelines also do not specify a requisite to do this testing. Information about the receptor expression types is fundamental for the treatment of breast cancer. We aimed to determine if there is significant discordance between the primary and ipsilateral axillary metastasis in early-stage breast cancer. Methods: We conducted a retrospective analysis via electronic medical record review of a large institutional database from 2008 to 2020. Sample for this study included all patients with a diagnosis of early-stage breast cancer (Stage I - III) with triple negative or HER2 positive tumors. Data on demographics, comorbidities, receptor status, staging, and mortality were collected. Results: Electronic charts from 448 patients were reviewed. 140 patients had axillary node positive disease. 40 (29%) of the 140 patients underwent testing for receptors subtypes on both primary and axillary nodal metastasis. 8 (20%) of the 40 patients had discordance in their receptor subtype expressed in their respective axillary nodal metastasis. 32 (80%) of the 40 patients had axillary receptor expression congruous to the primary tumor. At the time of our review, there was no statistically significant mortality between discordant compared to concordant group (13% vs 20%; p=0.54). 2 patients were lost to follow up. Conclusions: Our data suggests that one in every five axillary metastatic breast cancers can have receptor subtypes discordant compared to the receptors expressed on the primary tumor. Knowledge about any such discordance between the primary and respective axillary metastasis has a consequential impact on the treatment approach for early-stage breast cancer. This is especially true if the patient’s nodal metastatic lesions indeed prove HER2 receptor positivity or do not express any receptors (TNBC). Consequently, patients may be being deprived of benefits from advances in treatment of these cancers, such as targeted therapies towards HER2 receptor, hormonal treatments when indicated, or the utilization of neoadjuvant chemotherapy. A strong case can be thus made to revise current standards to include receptor testing on all primary and synchronous axillary metastasis. Further testing is needed to validate our findings.

Are we ready to use PSMA as a theranostic biomarker in clinical practice for patients with breast cancer?

e13114 Background: Subtype classification for breast cancer (BC) patients is important for risk-stratification. Unfortunately, this parameter is not able to discriminate perfectly between high- and low-risk disease and the identification of an accurate biomarker to determine aggressiveness is still a clinical need. Prostate-specific membrane antigen (PSMA) could be important given that it has been reported to be expressed in BC tumor cells and even more in endothelial cells of tumor vessels. Methods: We analyzed 101 BCs of whom 22 luminal A, 34 Luminal B, 22 HER2 positive and 23 triple negative (TN) BC to assess whether PSMA expression by immunohistochemistry was different in tumor subtypes and was related to ki67 expression and stromal (tumour-infiltrating lymphocytes) TILs. PSMA positivity was calculated as the number of positive vessels on 10 fields at 40X magnifications. Kruskal Wallis’s test was used to assess difference in PSMA positivity among BC subgroups and Dunn’s test was performed for post-hoc comparisons; Spearman’s rho coefficient was calculated to analyze the correlation among PSMA, KI67 and TILs. Results: The median age at diagnosis of BC patients was 66 (min-max: 25-87 years). Seventy (69.3%) patients had ER>0 and 64 (63.4%) had PgR>0. The ductal histotype was present in 92 patients (91%). The majority of the patients had grade 3 tumors (55.4%). Considering the number of positive vessels, our results showed that median PSMA was higher in TNBC compared to Luminal A, Luminal B and HER2 positive tumors (p<0.001, p=0.001 and p=0.041, respectively). Ki67 was higher in TNBC compared to Luminal A, Luminal B and HER2 positive tumors (p<0.001, p<0.001 and p=0.001, respectively). We saw a correlation between PSMA and ki67, especially in HER2 positive tumors (p<0.001), while a correlation between PSMA and TILs was observed in Luminal A (p=0.028). The analysis of PSMA expression on the lymph nodes showed the same trend observed for the primary tumors given that it was higher in TNBC compared to HER2 positive and luminal cancers. Conclusions: Our results suggest that PSMA could be used as a theranostic biomarker in BC considering that it is highly expressed in more aggressive tumors and the possibility to treat PSMA expressing patients for anti-angiogenesis and/or radionuclide treatment.

A phase III randomized trial of radiotherapy optimization for low-risk HER2-positive breast cancer (HERO): NRG-BR008.

TPS613 Background: Breast radiotherapy (RT) is the standard of care for patients with early-stage breast cancer (BC) who undergo breast-conserving surgery (BCS). However, the magnitude of benefit of RT is less clear in BCS patients with low-risk disease who receive effective systemic therapy. Among patients with early-stage HER2-positive (HER2+) BC, 10-year locoregional recurrence has been reported as low as 1.5% following BCS, adjuvant chemotherapy and HER2-targeted therapy, and RT. Given these exceedingly favorable outcomes, with the addition of HER2-directed therapy, we seek to evaluate the feasibility of omitting RT among patients with early-stage HER2+ BC following BCS and appropriate systemic therapy. Methods: This is a phase III randomized trial for patients ≥40 years with early-stage, node-negative, HER2+ (IHC/FISH) BC treated with BCS with negative margins and sentinel lymph node biopsy or axillary dissection. Patients undergoing primary surgery must have pathologic T1 (≤2 cm) N0 disease, while patients receiving neoadjuvant therapy must have clinical T1-2 (with radiographically T≤3.0 cm) N0 disease and exhibit a pathologic complete response (ypT0N0) at surgery. All patients must receive cytotoxic chemotherapy and HER2-targeted therapy, either in the adjuvant or neoadjuvant setting. Stratification is by age (<60; ≥60), tumor size (≤1 cm; >1 cm), estrogen-receptor status (positive; negative), and systemic therapy sequencing (adjuvant vneoadjuvant). Patients will be randomized to standard breast RT in addition to continuation of trastuzumab to complete one year of treatment (Arm 1), or trastuzumab alone (Arm 2). Endocrine therapy will be recommended for patients with hormone-receptor positive tumors. The primary endpoint is the recurrence-free interval (RFI). Secondary endpoints include time to ipsilateral breast recurrence, locoregional recurrence, disease-free survival, and overall survival, in addition to the 7-year ipsilateral breast recurrence rate among those not receiving RT. A health-related quality of life sub-study will assess differences in patient-reported breast pain and worry. We estimate a 7-year RFI of 97.5% with RT and allow for a clinically acceptable decrement of 3.63% without RT (7-year RFI of 93.87%; HR 2.5) to establish omission of RT as non-inferior. NRG-BR008 aims to enroll 1,300 patients over 4.5 years, yielding 80% power to detect the non-inferiority of RT omission with a one-sided α=0.05. We expect to observe the required 38 RFI events within 6 years of additional follow-up. The NRG-BR008/HERO trial opened to accrual in March 2023. Accrual is 13/1,300 as of 02-05-2024. Clinical trial information: NCT05705401 .

AFT-50 EndoMAP: A phase IB/II multicohort study of targeted agents and/or immunotherapy for patients with recurrent or persistent endometrial cancer (EC).

TPS5642 Background: The landscape in the management of recurrent or persistent endometrial cancer (EC) continues to evolve. Anti-PD-1/PD-L1 immune checkpoint inhibitors (ICI) as monotherapy or when combined with the VEGF-targeted tyrosine kinase inhibitor, lenvatinib, have demonstrated promising response rates in patients (pts) with microsatellite instability-high (MSI-H)/mismatch repair-deficient (dMMR) and MS-stable (MSS)/MMR-proficient (MMRp) EC, respectively. Recent studies have also shown a benefit with adding ICI to standard of care chemotherapy in the frontline setting. Pts with MSI-H/dMMR tumors seem to derive the greatest benefit. Approximately, 30% of recurrent EC pts fall into this category. Pairing ICI with targeted therapies carries the potential to elicit prolonged anti-tumor effects. Atezolizumab (Atezo) is a humanized monoclonal PD-L1 inhibitor that has demonstrated monotherapy antitumor activity in relapsed recurrent EC, and other solid tumors (e.g. NSCLC, HCC) as monotherapy and as part of combinatorial therapy. The AFT-50/EndoMAP study is a phase IB/II non-randomized, multicenter, 2-arm, multi-cohort platform trial designed to evaluate the efficacy and safety of biomarker-driven combination regimens, both with Atezo (AFT-50A) and without Atezo (AFT-50B) with biomarker-defined targeted agents in pts with recurrent or persistent EC. Methods: Eligible pts have recurrent or persistent EC with no more than 2 prior lines of therapy. FoundationOne CDx (F1CDx) NGS assay will be used for genomic tumor profiling. In AFT-50A, pts may be eligible for one of the following doublets: Atezo+talazoparib (tumors with genomic loss of heterozygosity (gLOH ≥16%), Atezo+Trastuzumab emtansine (ERBB2/HER2 mutated or amplified tumors), and Atezo+Tiragolumab (MSI-H and/or TMB-H). The Atezo+bevacizumab (biomarker unmatched) and Atezo+ipatasertib (PIK3CA/PTEN/AKT1-altered tumors) cohorts have completed accrual. Each cohort will enroll ~20 pts with potential adjustment to account for statistical and clinical considerations. AFT-50A pts will receive Atezo in addition to a targeted agent (per study-approved dosing schedule) until progression, unacceptable toxicity, pt withdrawal, death, or study termination. AFT-50B pts will be eligible for inavolisib (PIK3CAm/PTEN and AKT1wt-altered tumors) + letrozole or giredestrant + abemaciclib (RB1wt, estrogen receptor positive tumors). The primary endpoint for AFT-50A is confirmed overall response rate (ORR) for each arm, and for AFT-50B is 6-month progression free survival. Secondary endpoints include disease control rate, duration of response, OS, safety and tolerability. As a platform study, additional arms may be added, as supported by evolving understanding of EC and molecular targets. EndoMAP is actively enrolling at 20 sites in the US with a target of 25 sites nationwide. Clinical trial information: NCT04486352 .

Selpercatinib in non-MTC, RET-mutated tumors: Efficacy in MEN-associated and other tumors.

3150 Background: Selpercatinib, a first-in-class highly selective and potent RET kinase inhibitor with CNS activity, is approved in multiple countries for the treatment of RET-activated cancers. Current indications for RET mutant disease are limited to MTC. This analysis examined if selpercatinib was effective in non-MTC, RET mutation positive tumors and whether certain RET mutations demonstrated better activity (n=23; data cut-off: 13Jan2023). Methods: The phase 1/2 LIBRETTO-001 trial (NCT03157128) enrolled pts with locally advanced/metastatic RET-altered solid tumors, including pts with RET mutations in tumors other than MTC. Mutations must be known to be activating based on activity in MTC or other published evidence. Primary endpoint was objective response rate (ORR) by independent review committee (IRC). Secondary endpoints included ORR by investigator (INV), duration of response (DoR), progression-free survival (PFS), and safety. Results: Fourteen different tumor types were identified among the 23 pts with non-MTC RET-mutated tumors. This included 8 tumors from the Multiple Endocrine Neoplasia (MEN) syndrome spectrum; adrenal (pheochromocytoma; n=5), paraganglioma (n=2), neuroendocrine (n=1) (Table). Most of the mutations were located in extracellular cysteine-rich domain (CRD) and in the tyrosine kinase domain (TKD) of RET. In 23 efficacy-evaluable pts, confirmed ORR by IRC was 21.7% (5/23, 95% CI: 7.5, 43.7). ORR by IRC for pts with MEN-associated tumors (n=8) was 37.5% while five of these pts (62.5%) had stable disease lasting at least 16 weeks (SD16+). ORR by IRC for the sub-population with pheochromocytoma (n=5) was 40.0% and for pts with tumors manifesting RET extracellular cysteine mutations (n=5) was 60.0%. Of the 15 pts with non-MEN-associated tumors, 2 pts (8.7%; mutation in TKD) had a partial response (both with NSCLC adenocarcinoma, of which one had co-existent MTC). For the overall pts, the median DoR was 12.2 months (95% CI: 3.8, NE) and median PFS was 5.5 months (95% CI: 1.8, 19.4). No new safety signals were identified compared to previous reports. One grade 5 AE, general physical health deterioration, was observed and deemed by INV as not related to selpercatinib. Conclusions: This study suggests that RET-mutated, MEN-associated cancers (adrenal, paraganglioma, neuroendocrine) may benefit from selpercatinib treatment, which could be mediated through mutations in the extracellular CRD. The non-MTC RET-mutated tumor types appear not to derive benefit from selpercatinib. Clinical trial information: NCT03157128 . [Table: see text]

Fusobacterium nucleatum to promote esophageal squamous cell carcinoma progression via CCL20/CCR6-mediated migration of macrophages to the tumour micro environment.

e14668 Background: Esophageal squamous cell carcinoma (ESCC) is one of the most common digestive malignant tumor in China. Recent studies have shown that Fusobacterium nucleatum ( F. nucleatum) promotes ESCC progression through various mechanisms. One of them is about changing the tumor micro- environment through cytokine–cytokine receptor interaction. Methods: From January 2022 to June 2023, a total of 34 patients with ESCC from 4th Hospital of Hebei Medical University thoracic surgery were enrolled. All of the patients did not apply any neoadjuvant therapy before and received radical resection. Real-time reverse transcriptase - PCR (RT-PCR) were performed to examine the expressions of F. nucleatum in tumor tissues and para-tumor tissue. According to the CT values of the RT-PCR results, the level of the F. nucleatum infection could be separated in two groups - positive group and negative group. Immunohistochemistry (IHC) staining were used to examine the expressions of chemokine CCL20 in both groups. Immunofluorescence (IF) was characterised homing receptors CCR6 on CD206+ macrophages. In addition, transwell assay was carried on to quantify macrophages migration ability towards chemokines CCL20 in vitro. Results: F. nucleatum DNA positivity was significantly associated with higher expression of chemokine CCL20 and accumulation of CD68+CD206+ macrophages. F. nucleatum DNA positivity was also significantly correlated with worse histopathological grading. Otherwise, there were no significant correlation between F. nucleatum infection and gender, age, tobacco or alcohol use, T or N grade, TNM stage, tumor locations, blood vessel or nerve invasion and tumor size. IHC showed that the expression of CCL20 were higher in F. nucleatum DNA positive tumor tissue. After coculture with F. nucleatum and KYSE30 cell lines in vitro, the CCL20 production by KYSE30 cells were accelerated. In addition, immunofluorescence showed that CCL20 could recruit M2-like macrophages into the tumor environment by bonding CCR6 existed on the cell surface. Furthermore, the migration ability of macrophages was distinctly elevated by CCL20 result from F. nucleatum infection. Conclusions: F. nucleatum promotes esophageal squamous cell carcinoma progression via CCL20/CCR6-mediated migration of M2-like macrophages to the tumor micro- environment and deteriorates the suppression of the local immune micro- environment within the tumor. Such bacteria may be a biomarker to predict the efficacy of immunotherapy in ESCC. [Table: see text]