Background Autologous 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.

Methods Sub-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.

Results As 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.

Conclusions Afami-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 Registration NCT03132922

References

1. Van Tine BA, et al. CTOS 2020.

2. Hong DS, et al. ASCO 2020.

3. Hong DS, et al. SITC 2020.

4. De Selm C, et al. Mol Ther 2018;26(11):2542–2552.