Leukemia escape in immune desert: intraocular relapse of pediatric pro-B-ALL during systemic control by CD19-CAR T cells

Incidence of CD19-negative relapse after CD19-targeted immunotherapy in R/R BCP acute lymphoblastic leukemia: a review

There are inconsistencies in the reporting of CD19 antigen status following treatment with CD19-targeted therapies. A majority of evidence comes from studies reporting small sample sizes. In this review, we systematically summarize published studies that have reported rates of CD19-negative relapse after treatment with either blinatumomab or CD19-directed CAR T-cell therapy and report the rates of CD19-negative relapse when evaluated in a standardized way across trials. CD19-negative relapse appears to occur more commonly in relapses following CAR T-cell therapy compared with blinatumomab, whether proportions are calculated among all treated patients (8.7% vs 4.5%) or among patients who relapse (30% vs 22.5%). The median (range) duration of follow-up was 29.3 (17.4-50.8) and 20.4 (6.9-49.0) months for publications on blinatumomab (n = 10) and CAR T-cell therapies (n = 23), respectively. There is a need for standardized reporting of CD19 antigen status in the setting of relapse following novel immunotherapies to inform clinical practice.

PRESUMPTIVE RECURRENCE OF INTRAOCULAR LYMPHOMA DESPITE CHIMERIC ANTIGEN RECEPTOR T-CELL THERAPY

PURPOSE

To present the first reported case of presumptive intraocular recurrence of lymphoma following Chimeric Antigen Receptor (CAR) T-cell therapy despite systemic control by CD19-CAR T cells.

METHODS

Observational case report.

RESULTS

A 59-year-old man with diffuse, large, B-cell lymphoma subsequently developed secondary central nervous system disease despite chemotherapy. He underwent stem cell transplantation but relapsed again and was scheduled to receive CAR T-cell therapy. He developed vitritis several weeks before treatment, with vitreous biopsy showing non-Hodgkin B-cell lymphoma. He received CAR T-cell therapy following the vitrectomy. He presented 3 months following CAR T-cell therapy with nonspecific right eye floaters and discomfort, with the optical coherence tomography revealing subretinal saw-tooth deposits in the right eye, highly suggestive of lymphoma. This is despite having good systemic control with no other disease elsewhere in the body. He received intravitreal methotrexate to good effect.

CONCLUSION

To our knowledge, this is the first case of a vitreoretinal lymphoma nonresponsive to CAR T-cell therapy, despite good central nervous system and systemic control. This is suggestive of anti-CD19 CAR T cells not trafficking into the eye in sufficient numbers to eliminate CD19-expressing neoplastic B cells. We suggest regular ophthalmic follow-up after CAR-T-cell therapy for patients where there is evidence of ocular involvement.

Hit and Run: Bilateral Massive Intraocular Lymphomatous Infiltration after CAR-T Therapy

PURPOSE

We report a case of bilateral intraocular infiltration of DLBCL after CAR-T therapy.

METHODS

Retrospective case report.

RESULTS

A 62-year-old Caucasian male with medical history of high-grade DLBCL presented with papillitis and vitritis upon completion of CAR-T therapy. Thorough infectious and diagnostic work-ups were performed. Diagnostic vitreous tap revealed intraocular lymphoma. The patient received external beam radiotherapy to both orbits with dramatic improvement in disc edema and vitritis. However, subsequent MRI showed development of intracranial metastatic disease, and the patient died within the same month.

CONCLUSION

Atypical intraocular metastasis of DLBCL may occur following CAR-T therapy and may indicate secondary changes in immunosurveillance within immune-privileged sites such as the eye.

A novel CD19/CD22/CD3 trispecific antibody enhances therapeutic efficacy and overcomes immune escape against B-ALL

The bispecific T-cell engager (BiTE) blinatumomab against CD19 and CD3 has emerged as the most successful bispecific antibody (bsAb) to date; however, a significant proportion of patients do not respond to the treatments or eventually experience relapse after an initial response, and the recurrence rate increases significantly due to escape or downregulation of the CD19 antigen. To enhance antitumor efficacy and overcome potential immune escape, we developed a novel approach to design a CD19/CD22/CD3 trispecific antibody (tsAb) by site-specifically fusing anti-CD19 scFv (FMC63) and anti-CD22 nanobody (Nb25) to the defined sites of the CD3 antigen-binding fragment (Fab, SP34). This strategy allows for the optimal formation of immune synapses mediated by CD19/CD22/CD3 between target cells and T cells. Optimized tsAb can be superior for inducing T-cell-specific cytotoxicity and cytokine production against CD19+ and/or CD22+ tumor cells compared to other tsAb formats, and demonstrated significantly enhanced antitumor efficacy and the ability to overcome immune escape compared with the corresponding bsAbs alone or in combination, as well as with blinatumomab. In addition, tsAb treatment can lead to the long-term elimination of primary B-ALL patient samples in the PDX model and significantly prolong survival. This novel approach provides unique insight into the structural optimization of T-cell-redirected multispecific antibodies using site-specific recombination, and may be broadly applicable to heterogeneous and resistant tumor populations as well as solid tumors.

Chimeric antigen receptors containing the OX40 signalling domain enhance the persistence of T cells even under repeated stimulation with multiple myeloma target cells

Persistence of CAR-T cell function is associated with relapse rate after CAR-T therapy, while co-stimulatory agents are highly concerned with the persistence of CAR-T cells. In this study, we designed and constructed a series of BCMA-targeting second-generation CAR constructs containing CD28, 41BB, and OX40 molecules, respectively, to identify the costimulatory domains most favorable for persistence. The results of routine in vitro studies showed that OX40-CAR-T and 41BB-CAR-T had similar antitumor effects and were superior to CD28-CAR-T in terms of proliferation and cytotoxicity. Although difficult to distinguish by conventional functional assays, OX40-CAR-T cells exhibited greater proliferation and enhanced immune memory than 41BB-CAR-T cells with the repeated stimulation assay by BCMA-expressing target cells. In vivo studies further demonstrated that OX40-CAR-T cells had stronger proliferative activity than 41BB-CAR-T cells, which was highly consistent with the in vitro antitumor activity and proliferation results. Our study provides for the first time a scientific basis for designing OX40-CAR-T cell therapy to improve relapse in patients with MM after CAR-T treatment.

Hematopathologic Correlates of CAR T-Cell Therapy

CD19-targeting chimeric antigen rector (CAR) T-cell products are used for the treatment of relapsed/refractory B-acute lymphoblastic leukemia, diffuse large B-cell lymphoma, and mantle cell lymphoma. The success of CD19-CAR-T cells has led to the investigation of CAR T-cell products targeting different antigens in other hematological malignancies and solid tumors. Clinical laboratories play an important role in the manufacture, distribution, and monitoring of CAR T-cell therapy. Hence, it is important for laboratory professionals to be cognizant of clinicopathologic aspects of CAR T-cell therapy.