Treatment of Patients With Metastatic Cancer Using a Major Histocompatibility Complex Class II-Restricted T-Cell Receptor Targeting the Cancer Germline Antigen MAGE-A3

Abstract

Purpose Adoptive transfer of genetically modified T cells is being explored as a treatment for patients with metastatic cancer. Most current strategies use genes that encode major histocompatibility complex (MHC) class I-restricted T-cell receptors (TCRs) or chimeric antigen receptors to genetically modify CD8⁺ T cells or bulk T cells for treatment. Here, we evaluated the safety and efficacy of an adoptive CD4⁺ T-cell therapy using an MHC class II-restricted, HLA-DPB1*0401-restricted TCR that recognized the cancer germline antigen, MAGE-A3 (melanoma-associated antigen-A3). Patients and Methods Patients received a lymphodepleting preparative regimen, followed by adoptive transfer of purified CD4⁺ T cells, retrovirally transduced with MAGE-A3 TCR plus systemic high-dose IL-2. A cell dose escalation was conducted, starting at 10⁷ total cells and escalating at half-log increments to approximately 10¹¹ cells. Nine patients were treated at the highest dose level (0.78 to 1.23 × 10¹¹ cells). Results Seventeen patients were treated. During the cell dose-escalation phase, an objective complete response was observed in a patient with metastatic cervical cancer who received 2.7 × 10⁹ cells (ongoing at ≥ 29 months). Among nine patients who were treated at the highest dose level, objective partial responses were observed in a patient with esophageal cancer (duration, 4 months), a patient with urothelial cancer (ongoing at ≥ 19 months), and a patient with osteosarcoma (duration, 4 months). Most patients experienced transient fevers and the expected hematologic toxicities from lymphodepletion pretreatment. Two patients experienced transient grade 3 and 4 transaminase elevations. There were no treatment-related deaths. Conclusion These results demonstrate the safety and efficacy of administering autologous CD4⁺ T cells that are genetically engineered to express an MHC class II-restricted antitumor TCR that targets MAGE-A3. This clinical trial extends the reach of TCR gene therapy for patients with metastatic cancer.

Fig 1.

Clinical responses of patients 6, 11, and 16. (A) Computed tomography (CT) scans of the neck of patient 6 with metastatic cervical cancer before (left) and 29 months after (right) T-cell therapy. (B) Magnetic resonance imaging scans of patient 11 with metastatic urothelial cancer before (left) and 18 months after (right) T-cell therapy. (C) CT scans of the chest of patient 16 with metastatic osteosarcoma before (left) and approximately 4 months after (right) T-cell therapy. Arrows indicate the locations of metastatic lesions before and after therapy.

Fig 2.

Elevated serum cytokine levels after adoptive transfer of MAGE-A3 (melanoma-associated antigen-A3) T-cell receptor–transduced CD4⁺ T cells. Serum samples were collected daily during hospitalization. Maximum serum cytokine levels and the corresponding time point after cell infusion are shown. Day 0 is the cell infusion day. Patients with objective responses are labeled in yellow. Low dose: 0.001 to 3 × 10¹⁰ total cells. High dose: Approximately 10¹¹ total cells. n.d., not detectable. **Patients 5 and 8 had elevated interferon gamma (IFN-γ) levels before cell infusion (approximately 500 pg/mL and 4,000 pg/mL, respectively), and IFN-γ levels remained at similar levels after cell infusion.

Fig 3.

After cell infusion, T-cell receptor (TCR)–transduced T cells persisted better in the high-dose group compared with the low-dose group. (A) Peripheral blood lymphocyte (PBL) samples before (top) and approximately 1 month after (bottom) T-cell therapy were stained with anti-mouse TCRβ constant region antibody (mTCRβ) to detect MAGE-A3 (melanoma-associated antigen-A3) TCR-transduced T cells. A representative result is shown. (B) Percentage of CD4⁺mTCRβ⁺ cells in lymphocyte populations at approximately 1 month in the low-dose and high-dose patients. (C) Cell numbers of CD4⁺mTCRβ⁺ cells in patients’ peripheral blood. The post-treatment PBL sample from patient 4 was not available. Statistical significance was determined by Mann-Whitney U test. Patients who experienced objective responses are labeled with gray circles. CR, complete response; PR, partial response.

Fig A1.

Computed tomography scans of patient 9 with metastatic esophageal cancer before and 4 months after T-cell therapy.

Fig A2.

Serum cytokine levels before and after cell infusion. Patients 5 and 8 had elevated interferon gamma (IFN-γ) levels before cell infusion (approximately 500 pg/mL and 4,000 pg/mL, respectively), and the IFN-γ levels remained at similar levels after cell infusion (data not shown). CR, complete response; PR, partial response.

Fig A3.

MAGE-A3 (melanoma-associated antigen-A3) T-cell receptor (TCR)–transduced CD4⁺ T cells did not convert to regulatory T cells after cell infusion. (A) Intracellular staining for FOXP3 antibody was performed for peripheral blood lymphocyte samples before (top) and approximately 1 month after (bottom) T-cell therapy. (B) Percentage of CD4⁺mTCRβ⁺FOXP3⁺ cells in lymphocyte populations before (top) and 1 month after (bottom) cell infusion. (C) Percentage of CD4⁺mTCRβ⁻FOXP3⁺ cells in lymphocyte populations before (top) and 1 month after (bottom) cell infusion. Statistical significance was determined by Mann-Whitney U test.