Robust immune responses to SARS-CoV-2 in a pediatric patient with B-Cell ALL receiving tisagenlecleucel

Recipients of anti-CD19 targeted therapies such as chimeric antigen receptor (CAR)-T cell are considered at high risk for complicated Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV-2) infection due to prolonged B cell aplasia and immunosuppression. These patients represent a unique cohort and so far, immune responses to SARS-CoV-2 have not been well characterized in this setting. We report a pediatric patient with B-cell acute lymphoblastic leukemia (B-ALL) who had asymptomatic SARS-CoV-2 infection while receiving blinatumomab, followed by lymphodepletion (LD) and tisagenlecleucel, a CD19 targeting CAR-T therapy. The patient had a complete response to tisagenlecleucel, did not develop cytokine release syndrome, or worsening of SARS-CoV-2 during therapy. The patient had evidence of ongoing persistence of IgG antibody responses to spike and nucleocapsid after LD followed by tisagenlecleucel despite the B-cell aplasia. Further we were able to detect SARS-CoV-2 specific T-cells recognizing multiple viral structural proteins for several months following CAR-T. The T-cell response was polyfunctional and predominantly CD4 restricted. This data has important implications for the understanding of SARS-CoV-2 immunity in patients with impaired immune systems and the potential application of SARS-CoV-2-specific T-cell therapeutics to treat patients with blood cancers who receive B cell depleting therapy.

Tumor-associated antigen-specific T cells with nivolumab are safe and persist in vivo in relapsed/refractory Hodgkin lymphoma

Hodgkin lymphoma (HL) Reed Sternberg cells express tumor-associated antigens (TAA) that are potential targets for cellular therapies. We recently demonstrated that TAA-specific T cells (TAA-Ts) targeting WT1, PRAME, and Survivin were safe and associated with prolonged time to progression in solid tumors. Hence, we evaluated whether TAA-Ts when given alone or with nivolumab were safe and could elicit antitumor effects in vivo in patients with relapsed/refractory (r/r) HL. Ten patients were infused with TAA-Ts (8 autologous and 2 allogeneic) for active HL (n = 8) or as adjuvant therapy after hematopoietic stem cell transplant (n = 2). Six patients received nivolumab priming before TAA-Ts and continued until disease progression or unacceptable toxicity. All 10 products recognized 1 or more TAAs and were polyfunctional. Patients were monitored for safety for 6 weeks after the TAA-Ts and for response until disease progression. The infusions were safe with no clear dose-limiting toxicities. Patients receiving TAA-Ts as adjuvant therapy remain in continued remission at 3+ years. Of the 8 patients with active disease, 1 patient had a complete response and 7 had stable disease at 3 months, 3 of whom remain with stable disease at 1 year. Antigen spreading and long-term persistence of TAA-Ts in vivo were observed in responding patients. Nivolumab priming impacted TAA-T recognition and persistence. In conclusion, treatment of patients with r/r HL with TAA-Ts alone or in combination with nivolumab was safe and produced promising results. This trial was registered at www.clinicaltrials.gov as #NCT022039303 and #NCT03843294.

SARS-CoV-2-specific T cells are rapidly expanded for therapeutic use and target conserved regions of the membrane protein

T-cell responses to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have been described in recovered patients, and may be important for immunity following infection and vaccination as well as for the development of an adoptive immunotherapy for the treatment of immunocompromised individuals. In this report, we demonstrate that SARS-CoV-2-specific T cells can be expanded from convalescent donors and recognize immunodominant viral epitopes in conserved regions of membrane, spike, and nucleocapsid. Following in vitro expansion using a good manufacturing practice-compliant methodology (designed to allow the rapid translation of this novel SARS-CoV-2 T-cell therapy to the clinic), membrane, spike, and nucleocapsid peptides elicited interferon-γ production, in 27 (59%), 12 (26%), and 10 (22%) convalescent donors (respectively), as well as in 2 of 15 unexposed controls. We identified multiple polyfunctional CD4-restricted T-cell epitopes within a highly conserved region of membrane protein, which induced polyfunctional T-cell responses, which may be critical for the development of effective vaccine and T-cell therapies. Hence, our study shows that SARS-CoV-2 directed T-cell immunotherapy targeting structural proteins, most importantly membrane protein, should be feasible for the prevention or early treatment of SARS-CoV-2 infection in immunocompromised patients with blood disorders or after bone marrow transplantation to achieve antiviral control while mitigating uncontrolled inflammation.

EPCT-15. THE REMIND TRIAL: MULTI-ANTIGEN TARGETED T CELLS FOR PEDIATRIC CNS TUMORS

BACKGROUND

Patients with relapsed CNS malignancies or DIPG face terrible prognoses. We hypothesized that T cells specific for 3 tumor-associated antigens (TAA), WT1, PRAME and survivin, would be safe and elicit anti-tumor immunity.

METHODS

Patients (n=9) have received autologous tumor antigen-associated T cells (TAAT) (up to 4x10⁷/m²) for newly diagnosed DIPG (Group A) or recurrent CNS malignancies (Group B) on a Phase I dose-escalation study (NCT03652545) and were monitored for safety and response. RESULTS/

DISCUSSION

9/9 patients who received TAAT completed the 45-day safety monitoring phase with no dose-limiting toxicities. Infused cells were predominantly CD3+ T cells (median 96%; range: 87–99%), with CD4+ and CD8+ comprising 16% (range: 5–87%) and 40% (range: 4–67%) of the CD3+ cells, respectively. TAAT with specificity for 1–3 TAAs, at varying frequencies, was demonstrated in 8/9 TAAT by anti-IFN-γ ELISPOT. Plasma cytokine profiles demonstrated infusion-related immune cytokine responses. In summary, TAAT are safe and may elicit anti-tumor responses in vivo. To confirm TAAT-driven effects, we are evaluating plasma proteomic profiles for immune-response signatures and assessing unique T cell receptor rearrangements of infused TAAT. Response assessment and dose escalation are ongoing.

CTIM-33. THE REMIND TRIAL: MULTI-ANTIGEN TARGETED T CELLS FOR PEDIATRIC CNS TUMORS

BACKGROUND

Patients with relapsed CNS malignancies or DIPG face terrible prognoses. We hypothesized that T cells specific for 3 tumor-associated antigens (TAA), WT1, PRAME and survivin, would be safe and elicit anti-tumor immunity.

METHODS

Patients (n=15) received autologous tumor antigen-associated T cells (TAAT) (up to 4x107/m2) for newly diagnosed DIPG (Group A) or recurrent CNS malignancies (Group B) on a Phase I dose-escalation study (NCT03652545) and were monitored for safety and response.

RESULTS/DISCUSSION

15/15 patients who received TAAT completed the 45-day safety monitoring phase with no dose-limiting toxicities. Adverse events were minimal despite multiple pretreatments in Group B. Infused cells were predominantly CD3+ T cells (median 96%; range: 87–99%), with CD4+ and CD8+ comprising 16% (range: 5–87%) and 40% (range: 4–67%) respectively. Specificity for 1–3 TAAs was demonstrated in 13/15 TAAT by a-IFN-γ ELISPOT. Plasma cytokine and proteomic analyses are ongoing but have demonstrated dynamic post-infusion immune cytokine and protein responses. Increases in the inflammatory and immune-stimulatory cytokines IL-1b, IL-6, IL-2 and IL-7 were observed post-infusion in most patients evaluated. Infusion-related increases in regulatory cytokines IL-10 and IL-13 were also observed in 4/7 patients. These results are consistent with an infusion-mediated immune response in vivo. Of 9 patients who have been tested thus far, 29/92 plasma proteins showed significant differences between dose levels 1 and 2, including increased IL-7 (p < 0.0004) and CD40L (p < 0.046) and reduced IL-4 (p < 0.0004). T cell receptor sequencing data on in vivo TAAT persistence is pending. In summary, TAAT have thus far been safe and elicit immune responses in vivo. Clinical and immunologic response assessments are ongoing.