Affinity-optimized T cell receptors can enhance the potency of adoptive T cell therapy. Afamitresgene autoleucel (afami-cel) is a human leukocyte antigen-restricted autologous T cell therapy targeting melanoma-associated antigen A4 (MAGE-A4), a cancer/testis antigen expressed at varying levels in multiple solid tumors. We conducted a multicenter, dose-escalation, phase 1 trial in patients with relapsed/refractory metastatic solid tumors expressing MAGE-A4, including synovial sarcoma (SS), ovarian cancer and head and neck cancer (NCT03132922). The primary endpoint was safety, and the secondary efficacy endpoints included overall response rate (ORR) and duration of response. All patients (N = 38, nine tumor types) experienced Grade ≥3 hematologic toxicities; 55% of patients (90% Grade ≤2) experienced cytokine release syndrome. ORR (all partial response) was 24% (9/38), 7/16 (44%) for SS and 2/22 (9%) for all other cancers. Median duration of response was 25.6 weeks (95% confidence interval (CI): 12.286, not reached) and 28.1 weeks (95% CI: 12.286, not reached) overall and for SS, respectively. Exploratory analyses showed that afami-cel infiltrates tumors, has an interferon-γ-driven mechanism of action and triggers adaptive immune responses. In addition, afami-cel has an acceptable benefit–risk profile, with early and durable responses, especially in patients with metastatic SS. Although the small trial size limits conclusions that can be drawn, the results warrant further testing in larger studies.

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BackgroundADP-A2M10 specific peptide enhanced affinity receptor (SPEAR) T cells (ADP-A2M10) are genetically engineered autologous T cells that express a high-affinity melanoma-associated antigen A10 (MAGE-A10)-specific T-cell receptor (TCR) targeting MAGE-A10+ tumors in the context of human leukocyte antigen (HLA)-A*02. ADP-0022-003 was a phase I dose-escalation trial that aimed to evaluate the safety and antitumor activity of ADP-A2M10 in non-small cell lung cancer (NSCLC) (NCT02592577).MethodsEligible patients were HLA-A*02 positive with advanced NSCLC expressing MAGE-A10. Patients underwent apheresis; T cells were isolated, transduced with a lentiviral vector containing the TCR targeting MAGE-A10, and expanded. Patients underwent lymphodepletion with varying doses/schedules of fludarabine and cyclophosphamide prior to receiving ADP-A2M10. ADP-A2M10 were administered at 0.08–0.12×109 (dose group 1), 0.5–1.2×109 (dose group 2), and 1.2–15×109 (dose group 3/expansion) transduced cells.ResultsEleven patients (male, n=6; female, n=5) with NSCLC (adenocarcinoma, n=8; squamous cell carcinoma, n=3) were treated. Five, three, and three patients received cells in dose group 1, dose group 2, and dose group 3/expansion, respectively. The most frequently reported grade ≥3 adverse events were lymphopenia (n=11), leukopenia (n=10), neutropenia (n=8), anemia (n=6), thrombocytopenia (n=5), and hyponatremia (n=5). Three patients presented with cytokine release syndrome (grades 1, 2, and 4, respectively). One patient received the highest dose of lymphodepletion (fludarabine 30 mg/m2 on days –5 to –2 and cyclophosphamide 1800 mg/m2 on days −5 to −4) prior to a second infusion of ADP-A2M10 and had a partial response, subsequently complicated by aplastic anemia and death. Responses included: partial response (after second infusion; one patient), stable disease (four patients), clinical or radiographic progressive disease (five patients), and not evaluable (one patient). ADP-A2M10 were detectable in peripheral blood and in tumor tissue. Peak persistence was higher in patients who received higher doses of ADP-A2M10.ConclusionsADP-A2M10 demonstrated an acceptable safety profile and no evidence of toxicity related to off-target binding or alloreactivity. There was persistence of ADP-A2M10 in peripheral blood as well as ADP-A2M10 trafficking into the tumor. Given the discovery that MAGE-A10 and MAGE-A4 expression frequently overlap, this clinical program closed as trials with SPEAR T cells targeting MAGE-A4 are ongoing.

BackgroundADP-A2M10 specific peptide enhanced affinity receptor (SPEAR) T-cells are genetically engineered autologous T-cells that express a high-affinity melanoma-associated antigen (MAGE)-A10-specific T-cell receptor (TCR) targeting MAGE-A10-positive tumors in the context of human leukocyte antigen (HLA)-A*02. ADP-0022-004 is a phase 1, dose-escalation trial to evaluate the safety and anti-tumor activity of ADP-A2M10 in three malignancies (https://clinicaltrials.gov: NCT02989064).MethodsEligible patients were HLA-A*02 positive with advanced head and neck squamous cell carcinoma (HNSCC), melanoma, or urothelial carcinoma (UC) expressing MAGE-A10. Patients underwent apheresis; T-cells were isolated, transduced with a lentiviral vector containing the MAGE-A10 TCR, and expanded. Patients underwent lymphodepletion with fludarabine and cyclophosphamide prior to receiving ADP-A2M10. ADP-A2M10 was administered in two dose groups receiving 0.1×109 and >1.2 to 6×109 transduced cells, respectively, and an expansion group receiving 1.2 to 15×109 transduced cells.ResultsTen patients (eight male and two female) with HNSCC (four), melanoma (three), and UC (three) were treated. Three patients were treated in each of the two dose groups, and four patients were treated in the expansion group. The most frequently reported adverse events grade ≥3 were leukopenia (10), lymphopenia (10), neutropenia (10), anemia (nine), and thrombocytopenia (five). Two patients reported cytokine release syndrome (one each with grade 1 and grade 3), with resolution. Best response included stable disease in four patients, progressive disease in five patients, and not evaluable in one patient. ADP-A2M10 cells were detectable in peripheral blood from patients in each dose group and the expansion group and in tumor tissues from patients in the higher dose group and the expansion group. Peak persistence was greater in patients from the higher dose group and the expansion group compared with the lower dose group.ConclusionsADP-A2M10 has shown an acceptable safety profile with no evidence of toxicity related to off-target binding or alloreactivity in these malignancies. Persistence of ADP-A2M10 in the peripheral blood and trafficking of ADP-A2M10 into the tumor was demonstrated. Because MAGE-A10 expression frequently overlaps with MAGE-A4 expression in tumors and responses were observed in the MAGE-A4 trial (NCT03132922), this clinical program closed, and trials with SPEAR T-cells targeting the MAGE-A4 antigen are ongoing.

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BackgroundAutologous cell therapies with an engineered T-cell receptor targeting MAGE-A4 have shown responses in patients with synovial sarcoma1 with additional responses in myxoid/round cell liposarcoma (MRCLS), head and neck, lung, esophagogastric junction, and melanoma cancers.2 3 Low-dose radiation may control tumor growth locally and modulate stroma of solid tumors,4 potentially facilitating T-cell infiltration into tumors and antitumor activity.MethodsSub-study designed to assess safety, tolerability, and efficacy in up to 10 patients with low-dose radiation in combination with lymphodepleting chemotherapy, followed by afami-cel (an autologous TCR cell T-cell therapy targeting MAGE-A4). Eligible patients are HLA-A*02^+ with MAGE-A4 expressing tumors including urothelial, melanoma, head and neck, ovarian, non-small cell lung, esophageal, gastric, synovial sarcoma, and MRCLS cancers. Patients receive afami-cel by infusion following low-dose radiation and lymphodepleting chemotherapy. Radiation was 4.2–7 Gy per lesion or isocenter (maximum of 5). Lymphodepleting regimen was IV fludarabine 30 mg/m^2/day for 4 days (−7 to −4) and cyclophosphamide 600 mg/m^2/day for 3 days (−7 to −5). Afami-cel doses ranged from 1.2 x 10^9 to 10 x 10^9 transduced cells. Pts receive afami-cel infusion on Day 1.ResultsAs of Dec 27, 2020, a total of 8 patients, including 4 patients (1 male) with melanoma (2), HNSCC (1), or ovarian (1) cancers received low-dose radiation and afami-cel. Most frequently reported AEs (4/4 pts) were leukopenia/decreased white blood cell count, lymphopenia/decreased lymphocyte count, and neutropenia/decreased neutrophil count; all of which were related to the lymphodepletion regimen. The most commonly (>1 patient) reported AEs considered related to T-cell infusion were cytokine release syndrome (2/4 pts) and fatigue (2/4 pts). Two patients had a total of 5 SAEs: adrenal insufficiency, hyperglycemia, neurotoxicity, pneumonia aspiration, and pneumothorax. The only SAE considered to be related to treatment was Grade 3 neurotoxicity. Best overall responses per RECIST 1.1: 1 partial response (melanoma, −42% in target lesions), 2 stable diseases (ovarian cancer, −23%; HNSCC, no change), and 1 patient did not have post-baseline scans yet. Translational analyses showed peripheral persistence and serum cytokine response profiles consistent with that of afami-cel monotherapy, whilst a relatively greater T cell infiltration in tumor biopsies was evident.ConclusionsAfami-cel with low-dose radiation has had an acceptable safety profile. Most AEs were consistent with those typically experienced by cancer patients undergoing lymphodepletion cytotoxic chemotherapy and cellular therapy. Infused T-cells were observed in tumor biopsies at high frequency, and one patient exhibited a clinical partial response.Trial RegistrationNCT03132922ReferencesVan Tine BA, et al. CTOS 2020.Hong DS, et al. ASCO 2020.Hong DS, et al. SITC 2020.De Selm C, et al. Mol Ther 2018;26(11):2542–2552.

517 Background: ADP-A2M4CD8 is a specific peptide enhanced affinity receptor mixed CD4+ and CD8+ T-cell therapy targeting the cancer testis antigen MAGE-A4 and modified with addition of a CD8α co-receptor designed to provide additional functionality to CD4+ T-cells. ADP-A2M4CD8 has demonstrated an acceptable benefit to risk profile in the Phase 1 SURPASS trial (NCT04044859) in HLA A*02–eligible patients with unresectable or metastatic tumors positive for MAGE-A4.1 Here we report updated clinical outcomes in patients with urothelial cancer (UC). Methods: SURPASS is a first-in-human trial consisting of a modified 3+3 dose-escalation design and an expansion cohort. Autologous T-cells are obtained by leukapheresis, transduced with a self-inactivating lentiviral vector expressing the MAGE-A4-specific T-cell receptor and the CD8α co-receptor, and infused back to the patients as ADP-A2M4CD8 following lymphodepleting chemotherapy. Primary and secondary objectives are safety and anti-tumor activity, respectively. Results: At ESMO 2022, we reported promising results from SURPASS in several tumour types.2 In the 43 evaluable patients, the overall response rate was 28%, including 1 complete response and 11 partial responses (PR), and an additional 2 unconfirmed PRs awaiting confirmatory scans (as of August 1, 2022). Data from the 7 evaluable patients in the UC subset (updated September 6, 2022) showed that 3 (43%) had a best overall response of PR, and 1 (14%) had an unconfirmed PR. Disease control rate was 100% (3 PR + 1 unconfirmed PR + 3 stable disease). Adverse events have been consistent with those typically observed with lymphodepletion chemotherapy or cellular therapy. This trial is ongoing; data from additional patients with UC treated by January 2023 and updated translational data will be presented. Conclusions: ADP-A2M4CD8 continues to show an acceptable benefit to risk profile in multiple MAGE-A4+ unresectable or metastatic tumors, and preliminary encouraging evidence of efficacy in UC. An additional treatment cohort has been included in the updated trial protocol to evaluate ADP-A2M4CD8 combined with nivolumab. 1. Hong DS, et al. E-poster 540P: ESMO 2021; Virtual. 2. Hong DS, et al. Ann Oncol 33(suppl_7); S331-S355, Abstract 735MO. ESMO 2022. Clinical trial information: NCT04044859 .

Afami-cel is a mixed CD4+ CD8+ autologous T-cell therapy engineered to target the cancer testis antigen melanoma-associated antigen A4 in HLA-A*02-positive patients with advanced/metastatic synovial sarcoma or myxoid/round cell liposarcoma (MRCLS). Pooled data from the Phase 1 (NCT03132922) and Phase 2 (SPEARHEAD-1, NCT04044768) trials of afami-cel showed an acceptable benefit to risk profile with an overall response rate of 36.2% and a median duration of response of 52.0 weeks.1 To support the continued investigation of potential mechanisms of durable anti-tumor activity, we previously showed that afami-cel induces broad and enduring peripheral cytokine responses2 and that afami-cel tumoral infiltration is associated with increased presence of activated and proliferative cytotoxic T-cells in the tumor microenvironment.3 Here, we report the results of translational analyses exploring the cooperation between afami-cel-induced innate and adaptive immune responses pooled from the Phase 1 and 2 trials. Methods included measurement of 92 biomarkers related to apoptosis, chemotaxis, metabolism, tumor immunity promotion/suppression, and vascular/tissue remodeling in pre- and post-infusion serum samples from 38 patients. We also conducted multiplex immunofluorescence and gene set variation analysis of Reactome immune system pathway categories and microenvironment cell populations in RNA sequencing data from pre- and post-infusion biopsies from ≥15 patients. Serum analyses showed that patients with a clinical benefit as defined by RECIST v1.1 had significantly greater post-infusion levels of chemotactic markers (Kruskal-Wallis; p<0.05 for partial response [PR] compared to progressive disease, p<0.01 for PR compared to stable disease), indicating higher signaling related to immune-cell recruitment towards lesions. Tumor analyses showed increased expression of genes associated with innate and adaptive immunity, and cytokine signaling, in post-infusion biopsies, including T-cell receptor signaling-related expression, which was consistent with relatively greater spatial protein detection of pro-immune infiltrate. This profile was associated with longer progression-free survival. In conclusion, our data suggest that afami-cel induces peripheral and tumoral innate and adaptive immune responses, a hallmark of durable anti-tumor activity. Updated patient sample data will be presented. 1. D'Angelo SP, et al. J Clin Oncol. 2022;40:16_suppl:11562. 2. D’Angelo SP, et al. Poster 146 presented at: CTOS 2021; Virtual. 3. Van Tine, BA et al. Paper 61 presented at: CTOS 2022; Vancouver, BC, Canada. Citation Format: Cheryl McAlpine, Martin Isabelle, Robyn Broad, Revashnee Naidoo, Ashley Liddle, Elizabeth Duperret, Paul Noto, Ruoxi Wang, Dzmitry Batrakou, Sumit Middha, Chris Evans. Afamitresgene autoleucel (afami-cel; formerly ADP-A2M4) demonstrates durable clinical responses by inducing broad immune engagement with anti-tumor activity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 892.