赤塚 美樹

Some patients undergoing immune checkpoint blockade treatment develop immune-related adverse events (irAEs) affecting multiple organs, but whether pituitary and thyroid dysfunction are prone to co-occur is unclear. A total of 1,014 patients treated at Nagoya University Hospital were prospectively assessed for pituitary and thyroid function, and HLAs were analyzed in patients with pituitary and/or thyroid irAEs. Pituitary irAE and thyroid irAE developed in 68 and 128 patients, respectively. The incidence of thyroid irAE was significantly higher in patients who developed pituitary irAE compared to those who did not [21/68 (30.9%) vs. 107/946 (11.3%), p <0.001], and the difference remained significant with tumor type and therapeutic agents used as stratified factors (Cochran-Mantel-Haenszel test, p = 0.001). The frequencies of HLA-DRB1*15:01 (12.5% vs. 7.6%, p = 0.049) and DRB1*15:02 (16.9% vs 10.6%, p = 0.025) were significantly higher in patients with pituitary irAE compared to those in a database containing Japanese subjects. The frequency of the DRB1*15:01-associated haplotype (DRB1*15:01-DQB1*06:02-DPB1*02:01) was significantly higher in patients who developed both pituitary and thyroid irAEs compared to the control (14.3% vs. 3.1%, p = 0.002), and the DRB1*15:02-associated haplotype (DRB1*15:02-DQB1*06:01-DPB1*09:01) frequency was significantly higher in patients who developed pituitary irAE but not thyroid irAE compared to the control (18.1% vs. 8.9%, p = 0.006); both findings were confirmed in the validation cohort comprising 92 patients with pituitary irAE from seven hospitals. In conclusion, pituitary and thyroid irAEs are prone to co-occur and HLA-DR15-associated haplotypes are related to this co-occurrence.

OBJECTIVE: To report a case of bilateral reversible optic neuropathy as the first sign of Waldenström macroglobulinemia (WM). METHODS: Observational case report. RESULTS: A 52-year-old man had a sudden loss of vision in the left eye. Examinations revealed the presence of a serum monoclonal immunoglobulin (IgM kappa) in the serum. Even after a session of steroid pulse therapy, optic neuropathy became bilateral and then resolved almost completely after 4 months. The condition progressed to WM with multiorgan lesions years later. There was no evidence of optic neuropathy recurrence. The literature revealed two cases of monoclonal gammopathy (MG): a 64-year-old man with multiple myeloma (MM) with IgA lambda and a 51-year-old man with MM with IgG kappa. These cases have similar conditions: 1) visual reduction as an initial symptom of MG, 2) bilateral involvement, 3) no sign of central nervous system (CNS) infiltration shown by normal brain magnetic resonance images, and 4) recovery to a visual acuity of ≥1.0 bilaterally with no reoccurrence. The excessive Igs or B-cell hyperactivity may activate an autoimmune mechanism that reversibly interferes with the bilateral optic nerves. CONCLUSION: Bilateral optic neuropathy was the initial symptom of WM. There was no evidence of CNS infiltration; it recovered and then did not reoccur. The pathogenesis remained unknown, but two cases of MG were reported in the literature with remarkably similar conditions.

Negative immunofixation electrophoresis (IFE) of serum and/or urine is a diagnostic marker for determining a complete response (CR) after immunotherapy for multiple myeloma (MM). However, residual therapeutic antibodies such as elotuzumab (IgG-κ), can compromise IFE evaluation when the affected immunoglobulins belong to the same IgG-κ subclass. We thus sought to develop a simple and rapid method to treat patient serum before IFE to distinguish the residual elotuzumab. Serum samples from patients receiving elotuzumab were treated with a predetermined amount of soluble signaling lymphocyte activation molecule F7 (SLAMF7) protein and then subjected to conventional IFE testing. We tested our method in samples from 12 patients. The IgG-κ band in IFE disappeared or shifted after elotuzumab treatment in four patients with no bone marrow minimal residual disease and normalized free light chain, whereas seven patients with any sign of residual MM showed a remaining IgG-κ band after treatment. One-hour incubation of samples with 6-9 molar excess soluble SLAMF7 before IFE was sufficient to distinguish residual elotuzumab in 11 of 12 samples. This simple method does not require special reagents, can be performed in most clinical laboratories, and enables differentiation between patients with a CR and those requiring further treatment.

Minor histocompatibility antigens (mHAgs) in allogeneic hematopoietic stem cell transplantation are highly immunogenic as they are foreign antigens and cause polymorphism between donors and recipients. Adoptive cell therapy with mHAg-specific T cells may be an effective option for therapy against recurring hematological malignancies following transplantation. Genetically modified T cells with T cell receptors (TCRs) specific to mHAgs have been developed, but formation of mispaired chimeric TCRs between endogenous and exogenous TCR chains may compromise their function. An alternative approach is the development of chimeric antigen receptor (CAR)-T cells with TCR-like specificity whose CAR transmembrane and intracellular domains do not compete with endogenous TCR for CD3 complexes and transmit their own activation signals. However, it has been shown that the recognition of low-density antigens by high-affinity CAR-T cells has poor sensitivity and specificity. This mini review focuses on the potential for and limitations of TCR-like CAR-T cells in targeting human leukocyte antigen-bound peptide antigens, based on their recognition mechanisms and their application in targeting mHAgs.

<title>Key Points</title> T cells expressing a CAR consisting of scFv #213 targeting WT1 peptide/HLA-A*2402 complex killed HLA-A*2402+ WT1+ tumor cell lines. The therapeutic efficacy of #213 scFv CAR-T cells was shown to be enhanced by DC vaccine in a murine xenograft model.

Selective graft-versus-tumor (GVT) reactivity with minimal risk of graft-versus-host disease (GVHD) following allogeneic stem cell transplantation is thought to be induced by targeting minor histocompatibility (H) antigens (Ags) expressed only on patients’ hematopoietic cells. Among HLA-A* 02:01 positive patients, minor H Ags such as HA-1 and HA-2 have been shown to be associated with anti-tumor responses with minimal GVHD and explored for application to adoptive immunotherapy. Because preparation of Ag-specific cytotoxic T cell clones (CTLs) or lines for adoptive immunotherapy is labor-intensive and time consuming, the genetic transfer of T-cell receptors (TCRs) directed toward target Ags into T lymphocytes has been used to efficiently generate anti-tumor T cells without the need for in vitro induction and expansion. Alternatively, T cells could be gene-modified with a chimeric antigen receptor (CAR) harnessing a single chain antibody moiety (scFv). The conventional CAR strategy has the limitation of only targeting cell surface Ags on target cells. One possible way to attain intracellular Ag targeting with a CAR is to generate a TCR-like monoclonal antibody (mAb) as a source of scFv. In this study, we sought to generate highly specific mAbs specific for HA-1H minor H Ag by immunizing mice with tetramerized recombinant HLA-A2 incorporating HA-1H minor H Ag peptides and β2-microglobulin (HA-1H/HLA-A2). We hypothesized that the use of HLA-A2 transgenic mice, which should be tolerant to human HLA-A2, would facilitate efficient induction of mAbs specific for peptides presented on HLA-A2. Phage libraries were generated from splenic B cells and screened by panning for clones reactive to plate-bound HA-1H/HLA-A2 in the presence of free MAGEA4/HLA-A2 for competition. Candidate scFv encoded by obtained phage clones were transformed to scFv tetrameric Ab form or introduced into T cells as CAR coupled to CD28 transmembrane and CD3ζ domains (CD28-ζ). A total of 144 clones were randomly selected from 8.1×108 clones that had been recovered after the third panning. Among 144 clones, 18 (12.5%) showed preferential binding to HA-1/HLA-A2, 137 showed similar binding to both pMHC complexes, and 7 showed reactivity to neither of them. One of 18 scFv Abs, clone #131, demonstrated high affinity (KD = 8.34nM) for the HA-1H/HLA-A2 complex. Primary human CD8 T cells transduced with #131 scFv-CD28-ζ were stained with HA-1H/HLA-A2 tetramers as strongly as a CTL clone, EH6, specific for endogenously HLA-A2- and HA-1H-positive cells. Unexpectedly, however, #131 scFv-CD28-ζ CAR-T cells required ∼100-fold higher Ag density when pulsed exogenously to exert cytotoxicity than did the cognate EH6-CTL. In addition, mAb blocking experiments demonstrated that #131 scFv-CD28-ζCAR-T cells were less sensitive to CD8 blockade when they were completely blocked with HA-1H/HLA-A2 tetramer. These data suggest that T cells with higher affinity antigen receptors than TCRs (average KD ranging between 1μM∼100μM) are less able to recognize low density peptide/MHC antigens as reported in the case of affinity-matured TCR or CAR, and that CD8+ CAR-T cells may not be necessarily CD8-dependent possibly due to failure to form complexes with CD3. <sec> <title>Disclosures:</title> No relevant conflicts of interest to declare. </sec>