ctDNA improves prognostic prediction for patients with relapsed/refractory MM receiving ixazomib, lenalidomide, and dexamethasone.

ABSTRACT: It remains elusive how driver mutations, including those detected in circulating tumor DNA (ctDNA), affect prognosis in relapsed/refractory multiple myeloma (RRMM). Here, we performed targeted-capture sequencing using bone marrow plasma cells (BMPCs) and ctDNA of 261 RRMM cases uniformly treated with ixazomib, lenalidomide, and dexamethasone in a multicenter, prospective, observational study. We detected 24 and 47 recurrently mutated genes in BMPC and ctDNA, respectively. In addition to clonal hematopoiesis-associated mutations, varying proportion of driver mutations, particularly TP53 mutations (59.2% of mutated cases), were present in only ctDNA, suggesting their subclonal origin. In univariable analyses, ctDNA mutations of KRAS, TP53, DIS3, BRAF, NRAS, and ATM were associated with worse progression-free survival (PFS). BMPC mutations of TP53 and KRAS were associated with inferior PFS, whereas KRAS mutations were prognostically relevant only when detected in both BMPC and ctDNA. A total number of ctDNA mutations in the 6 relevant genes was a strong prognostic predictor (2-year PFS rates: 57.3%, 22.7%, and 0% for 0, 1, and ≥2 mutations, respectively) and independent of clinical factors and plasma DNA concentration. Using the number of ctDNA mutations, plasma DNA concentration, and clinical factors, we developed a prognostic index, classifying patients into 3 categories with 2-year PFS rates of 57.9%, 28.6%, and 0%. Serial analysis of ctDNA mutations in 94 cases revealed that TP53 and KRAS mutations frequently emerge after therapy. Thus, we clarify the genetic characteristics and clonal architecture of ctDNA mutations and demonstrate their superiority over BMPC mutations for prognostic prediction in RRMM. This study is a part of the C16042 study, which is registered at www.clinicaltrials.gov as #NCT03433001.

Integrator complex subunit 15 controls mRNA splicing and is critical for eye development.

The eye and brain are composed of elaborately organized tissues, development of which is supported by spatiotemporally precise expression of a number of transcription factors and developmental regulators. Here we report the molecular and genetic characterization of Integrator complex subunit 15 (INTS15). INTS15 was identified in search for the causative gene(s) for an autosomal-dominant eye disease with variable individual manifestation found in a large pedigree. While homozygous Ints15 knockout mice are embryonic lethal, mutant mice lacking a small C-terminal region of Ints15 show ocular malformations similar to the human patients. INTS15 is highly expressed in the eye and brain during embryogenesis and stably interacts with the Integrator complex to support small nuclear RNA 3' end processing. Its knockdown resulted in missplicing of a large number of genes, probably as a secondary consequence, and substantially affected genes associated with eye and brain development. Moreover, studies using human iPS cells-derived neural progenitor cells showed that INTS15 is critical for axonal outgrowth in retinal ganglion cells. This study suggests a new link between general transcription machinery and a highly specific hereditary disease.

Autologous HSCT with novel agent-based induction and consolidation followed by lenalidomide maintenance for untreated multiple myeloma.

Triplet regimen comprising proteasome inhibitors, immunomodulatory drugs, and dexamethasone (DEX) is a recommended induction/consolidation therapy for multiple myeloma (MM) patients eligible for transplant. In this Japanese phase II study conducted from 2017 to 2019, newly diagnosed MM patients aged 20-65 received four induction cycles with bortezomib (Bor), lenalidomide (Len), and DEX (VRD), followed by Bor and high-dose melphalan with autologous stem cell rescue. Subsequently, they underwent four consolidation cycles with carfilzomib, Len, and DEX (KRD), followed by Len maintenance until disease progression. A total of 141 patients were analyzed. In an intent-to-treat population, the complete or better response post induction was 19.9%, rising to 39.7%, 58.9%, and 62.4% after transplant, consolidation, and 1-year maintenance, respectively. With a median follow-up of 38 months, the 3-year progression-free survival (PFS) rate was 83.5% and the 3-year overall survival rate was 92.5%. Severe adverse events (≥grade 3) occurred in ~30% of patients; however, there was no treatment-related mortality. These findings clearly showed the tolerability and effectiveness of this protocol. Nevertheless, patients with high-risk cytogenetics showed a trend toward lower 3-year PFS than those without (77.8% vs. 89.4%, p = 0.051), and ultra-high-risk cytogenetics (≥2 high-risk cytogenetics) had an even worse prognosis, with 61.2% 3-year PFS. To overcome this situation, a more potent treatment strategy incorporating novel agents such as the CD38-antibody should be assessed in future studies.

Outcomes of transplant-eligible patients with myelodysplastic syndrome with excess blasts registered in an observational study: The JALSG-CS11-MDS-SCT.

Allogeneic hematopoietic stem cell transplantation (allo-SCT) is the sole curative therapy for myelodysplastic syndrome (MDS). However, whether bridging therapy (BRT) including azacitidine (AZA) and combination chemotherapy (CCT) prior to allo-SCT should be performed is unclear. We analyzed BRT and the outcomes of patients with myelodysplastic syndrome with excess blasts (MDS-EB) who were ≤ 70 years old at the time of registration for a prospective observational study to clarify the optimal allo-SCT strategy for high-risk MDS. A total of 371 patients were included in this study. Among 188 patients (50.7%) who were considered for allo-SCT, 141 underwent allo-SCT. Among the patients who underwent allo-SCT, 64 received AZA, 29 received CCT, and 26 underwent allo-SCT without BRT as the initial treatment. Multivariate analysis identified BRT as an independent factor influencing overall survival (AZA vs. without BRT, hazard ratio [HR] 3.33, P = 0.005; CCT vs. without BRT, HR 3.82, P = 0.003). In multivariate analysis, BRT was independently associated with progression-free survival (AZA vs. without BRT: HR, 2.23; P = 0.041; CCT vs. without BRT: HR, 2.94; P = 0.010). Transplant-eligible patients with MDS-EB should undergo allo-SCT when clinically acceptable, and upfront allo-SCT without BRT may be superior to AZA or CCT.

A prospective, multicenter, observational study of ixazomib plus lenalidomide-dexamethasone in patients with relapsed/refractory multiple myeloma in Japan.

Real-world studies permit inclusion of a more diverse patient population and provide more information on the effectiveness of treatments used in routine clinical practice. This prospective, multicenter, observational study investigated the effectiveness and safety of ixazomib plus lenalidomide and dexamethasone (IRd) in 295 patients with relapsed/refractory multiple myeloma (RRMM) in routine clinical practice in Japan. Patients had a median age of 74 years, 80.0% were aged ≥ 65 years, 42.0% had received ≥ 3 lines of prior treatment, and 28.5% were "frail" according to the International Myeloma Working Group frailty score. After a median follow-up of 25.0 months, median progression-free survival (PFS) was 15.3 (95% CI 12.4-19.5) months, while median overall survival was not reached. The overall response rate was 53.9%, and 31.5% of patients had a very good partial response or better. In the subgroup analysis, median PFS was better in patients with 1 versus 2 or ≥ 3 lines of prior treatment (29.0 vs 19.2 or 6.9 months) and paraprotein versus clinical relapse (16.0 vs 7.9 months), but median PFS was not notably affected by frailty score or age group. Dose adjustment was more frequent among patients aged > 75 years, especially early after IRd treatment initiation. Treatment-emergent adverse events (TEAEs) of any grade occurred in 84.4% of patients and 24.7% of patients discontinued treatment due to TEAEs; no new safety concerns were found. These findings suggest that oral IRd triplet regimen is an effective and tolerable treatment option for RRMM patients in real-world settings outside of clinical trials.ClinicalTrials.gov identifier: NCT03433001; Date of registration: 14 February 2018.

Elranatamab in Japanese patients with relapsed/refractory multiple myeloma: results from MagnetisMM-2 and MagnetisMM-3.

BACKGROUND: Despite advances, most patients with multiple myeloma (MM) experience relapse and repeat multiple treatment lines, highlighting an unmet need for patients with relapsed or refractory MM (RRMM). Bispecific antibodies are a new option, but their efficacy and safety in Japanese patients are unknown. METHODS: This was an analysis of Japanese patients receiving elranatamab monotherapy in MagnetisMM-2 (NCT04798586) and MagnetisMM-3 (NCT04649359). Both studies evaluated a priming dose regimen of elranatamab followed by weekly subcutaneous doses, in patients with disease progression while receiving or who were intolerant to ≥3 prior therapies (≥1 proteasome inhibitor, ≥1 immunomodulatory drug and ≥1 anti-CD38 monoclonal antibody). The primary endpoints were dose limiting toxicities (DLTs) in MagnetisMM-2 and confirmed objective response rate (ORR) in MagnetisMM-3. In both, key secondary endpoints included safety, tolerability, duration of response, time to response, progression-free survival and overall survival. RESULTS: In MagnetisMM-2 (N = 4) and MagnetisMM-3 (n = 12), median ages were 68.5 and 66.5 years, respectively. No DLTs were observed in MagnetisMM-2. ORRs were 50.0% (95% CI, 6.8-93.2) and 58.3% (95% CI, 27.7-84.8) in MagnetisMM-2 and MagnetisMM-3, respectively. All patients experienced treatment-emergent adverse events in MagnetisMM-2 (grade 3/4: 75.0%) and MagnetisMM-3 (grade 3/4: 100%); cytokine release syndrome occurred in 100% (grade 3/4: 25.0%) and 58.3% (no grade 3/4) of patients, respectively. Neither study reported immune effector cell-associated neurotoxicity syndrome. CONCLUSIONS: No new safety signals were observed, and ORRs were similar to that of the overall MagnetisMM-3 trial population, supporting further studies of elranatamab in Japanese patients with RRMM. ClinicalTrials.gov identifier: NCT04798586 (MagnetisMM-2), NCT04649359 (MagnetisMM-3).

Glutamine Triggers Acetylation-Dependent Degradation of Glutamine Synthetase via the Thalidomide Receptor Cereblon.

Cereblon (CRBN), a substrate receptor for the cullin-RING ubiquitin ligase 4 (CRL4) complex, is a direct protein target for thalidomide teratogenicity and antitumor activity of immunomodulatory drugs (IMiDs). Here we report that glutamine synthetase (GS) is an endogenous substrate of CRL4(CRBN). Upon exposing cells to high glutamine concentration, GS is acetylated at lysines 11 and 14, yielding a degron that is necessary and sufficient for binding and ubiquitylation by CRL4(CRBN) and degradation by the proteasome. Binding of acetylated degron peptides to CRBN depends on an intact thalidomide-binding pocket but is not competitive with IMiDs. These findings reveal a feedback loop involving CRL4(CRBN) that adjusts GS protein levels in response to glutamine and uncover a new function for lysine acetylation.

Extracellular aaRSs drive autoimmune and inflammatory responses in rheumatoid arthritis via the release of cytokines and PAD4.

OBJECTIVES: Recent studies demonstrate that extracellular-released aminoacyl-tRNA synthetases (aaRSs) play unique roles in immune responses and diseases. This study aimed to understand the role of extracellular aaRSs in the pathogenesis of rheumatoid arthritis (RA). METHODS: Primary macrophages and fibroblast-like synoviocytes were cultured with aaRSs. aaRS-induced cytokine production including IL-6 and TNF-α was detected by ELISA. Transcriptomic features of aaRS-stimulated macrophages were examined using RNA-sequencing. Serum and synovial fluid (SF) aaRS levels in patients with RA were assessed using ELISA. Peptidyl arginine deiminase (PAD) 4 release from macrophages stimulated with aaRSs was detected by ELISA. Citrullination of aaRSs by themselves was examined by immunoprecipitation and western blotting. Furthermore, aaRS inhibitory peptides were used for inhibition of arthritis in two mouse RA models, collagen-induced arthritis and collagen antibody-induced arthritis. RESULTS: All 20 aaRSs functioned as alarmin; they induced pro-inflammatory cytokines through the CD14-MD2-TLR4 axis. Stimulation of macrophages with aaRSs displayed persistent innate inflammatory responses. Serum and SF levels of many aaRSs increased in patients with RA compared with control subjects. Furthermore, aaRSs released PAD4 from living macrophages, leading to their citrullination. We demonstrate that aaRS inhibitory peptides suppress cytokine production and PAD4 release by aaRSs and alleviate arthritic symptoms in a mouse RA model. CONCLUSIONS: Our findings uncovered the significant role of aaRSs as a novel alarmin in RA pathogenesis, indicating that their blocking agents are potent antirheumatic drugs.

Dysregulated TDP-43 proteostasis perturbs excitability of spinal motor neurons during brainstem-mediated fictive locomotion in zebrafish.

Spinal motor neurons (SMNs) are the primary target of degeneration in amyotrophic lateral sclerosis (ALS). Degenerating motor neurons accumulate cytoplasmic TAR DNA-binding protein 43 (TDP-43) aggregates in most ALS cases. This SMN pathology can occur without mutation in the coding sequence of the TDP-43-encoding gene, TARDBP. Whether and how wild-type TDP-43 drives pathological changes in SMNs in vivo remains largely unexplored. In this study, we develop a two-photon calcium imaging setup in which tactile-evoked neural responses of motor neurons in the brainstem and spinal cord can be monitored using the calcium indicator GCaMP. We devise a piezo-assisted tactile stimulator that reproducibly evokes a brainstem descending neuron upon tactile stimulation of the head. A direct comparison between caudal primary motor neurons (CaPs) with or without TDP-43 overexpression in contiguous spinal segments demonstrates that CaPs overexpressing TDP-43 display attenuated Ca2+ transients during fictive escape locomotion evoked by the tactile stimulation. These results show that excessive amounts of TDP-43 protein reduce the neuronal excitability of SMNs and potentially contribute to asymptomatic pathological lesions of SMNs and movement disorders in patients with ALS.

Efficacy and Safety of Ixazomib Plus Lenalidomide and Dexamethasone Following Injectable PI-Based Therapy in Relapsed/Refractory Multiple Myeloma.

This nationwide, multicenter, open-label, single-arm study evaluated the efficacy and safety of the oral proteasome inhibitor (PI), ixazomib plus lenalidomide (LEN) and dexamethasone (DEX) (IRd) following injectable PI-based therapy for relapsed/refractory multiple myeloma (RRMM). Of 45 patients enrolled, 36 patients received IRd after achieving at least a minor response to 3 cycles of bortezomib or carfilzomib plus LEN + DEX (VRd, n=6; KRd, n=30). At median follow-up of 20.8 months, the 12-month event-free survival rate (primary endpoint) was 49% (90% CI: 35.9-62.0), counting 11 events of progressive disease/death, 8 dropouts and 4 missing response data. The 12-month progression-free survival (PFS) rate by Kaplan-Meier analysis (dropouts as censoring) was 74% (95% CI: 56-86). Median PFS and time to next treatment (95% CI) were 29.0 (21.3-NE) and 32.3 (14.9-35.4) months, respectively; median OS was not evaluable. The overall response rate was 73%, and 42% of patients had a very good partial response or better. Frequent (≥10% incidence) grade ≥3 treatment emergent adverse events were decreased neutrophil and platelet counts (n=7 [16%] each). Two deaths occurred (one during KRd treatment and one during IRd treatment), both due to pneumonia. IRd following injectable PI-based therapy was tolerable and efficacious in RRMM patients. TRIAL REGISTRATION NUMBER: NCT03416374; Date of registration: January 31, 2018.

Short-chain fatty acids bind to apoptosis-associated speck-like protein to activate inflammasome complex to prevent Salmonella infection.

Short-chain fatty acids (SCFAs) produced by gastrointestinal microbiota regulate immune responses, but host molecular mechanisms remain unknown. Unbiased screening using SCFA-conjugated affinity nanobeads identified apoptosis-associated speck-like protein (ASC), an adaptor protein of inflammasome complex, as a noncanonical SCFA receptor besides GPRs. SCFAs promoted inflammasome activation in macrophages by binding to its ASC PYRIN domain. Activated inflammasome suppressed survival of Salmonella enterica serovar Typhimurium (S. Typhimurium) in macrophages by pyroptosis and facilitated neutrophil recruitment to promote bacterial elimination and thus inhibit systemic dissemination in the host. Administration of SCFAs or dietary fibers, which are fermented to SCFAs by gut bacteria, significantly prolonged the survival of S. Typhimurium-infected mice through ASC-mediated inflammasome activation. SCFAs penetrated into the inflammatory region of the infected gut mucosa to protect against infection. This study provided evidence that SCFAs suppress Salmonella infection via inflammasome activation, shedding new light on the therapeutic activity of dietary fiber.

Waldenström Macroglobulinemia and Non-IgM-Type Lymphoplasmacytic Lymphoma Are Genetically Similar.

INTRODUCTION: Waldenström macroglobulinemia (WM) represents a subset of lymphoplasmacytic lymphoma (LPL) with the immunoglobulin (Ig)M paraprotein. MYD88 L265P and CXCR4 mutations are common mutations in WM patients, and mutations in ARID1A and KMT2D (MLL2) have also been reported. However, little information has been accumulated on genetic changes in LPL with other paraproteins like IgG. METHODS: We therefore aimed to evaluate genetic differences between WM and LPL with non-IgM paraprotein (non-IgM-type LPL) using targeted next-generation sequencing (NGS) in 20 Japanese patients (10 with WM, 10 with non-IgM-type LPL). RESULTS: Mutations were detected in ARID1A (10%), CXCR4 (20%), MYD88 (90%), and KMT2D (0%) for WM patients and in ARID1A (10%), CXCR4 (20%), MYD88 (70%), and KMT2D (10%) for non-IgM-type LPL patients. No significant differences were identified. No mutations were detected in NOTCH2, PRDM1, CD274 (PD-L1), PDCD1LG2 (PD-L2), RAG2, MYBBP1A, TP53, or CD79B. DISCUSSION: Mutant allele frequency in MYD88 L265P did not differ significantly between WM and non-IgM-type LPL. Most mutations detected by NGS were subclonal following MYD88 L265P, although one non-IgM-type LPL patient harbored only CXCR4 S338X mutation. Our NGS analyses reveal genetic characteristics in LPL patients and suggest genetic similarities between these two subsets of LPL, WM and non-IgM-type.

Pre-treatment bronchoscopic evaluation in a case of relapsing polychondrits.

BACKGROUND: Relapsing polychondritis (RP) is a chronic and recurrent inflammatory disease of the cartilage tissues in the body. The cause of RP is unknown, and since it is a rare disease with symptoms that affect multiple organs, diagnosis is often delayed. CASE PRESENTATION: A 62-year-old woman with no smoking history visited our institution complaining of fever, cough, and dyspnoea. Chest CT showed a stenosis from the left main bronchus to the left lower lobe branch. Bronchoscopy visualised intense erythema and oedema at the left main bronchus, with airway narrowing. Biopsy of the ear revealed degenerative vitreous cartilage and fibrous connective tissue with a mild inflammatory cell infiltrate. She was subsequently diagnosed with RP and administered systemic corticosteroid therapy. Her symptoms improved rapidly, and post-treatment bronchoscopy revealed that although mild erythema of the airway epithelium remained, oedema markedly improved, and the airway stenosis was resolved. CONCLUSIONS: We report a case where pre-treatment bronchoscopy was able to visually confirm RP at the acute stage. Since RP is difficult to diagnose, severe airway narrowing can occur prior to diagnosis. Therefore, to determine the stage of the disease, it is helpful to perform bronchoscopic observation before treatment. However, bronchoscopic observation before treatment should be performed by experienced bronchoscopists due to the risk of airway obstruction.

Hypnotic effect of thalidomide is independent of teratogenic ubiquitin/proteasome pathway.

Thalidomide exerts its teratogenic and immunomodulatory effects by binding to cereblon (CRBN) and thereby inhibiting/modifying the CRBN-mediated ubiquitination pathway consisting of the Cullin4-DDB1-ROC1 E3 ligase complex. The mechanism of thalidomide's classical hypnotic effect remains largely unexplored, however. Here we examined whether CRBN is involved in the hypnotic effect of thalidomide by generating mice harboring a thalidomide-resistant mutant allele of Crbn (Crbn YW/AA knock-in mice). Thalidomide increased non-REM sleep time in Crbn YW/AA knock-in homozygotes and heterozygotes to a similar degree as seen in wild-type littermates. Thalidomide similarly depressed excitatory synaptic transmission in the cortical slices obtained from wild-type and Crbn YW/AA homozygous knock-in mice without affecting GABAergic inhibition. Thalidomide induced Fos expression in vasopressin-containing neurons of the supraoptic nucleus and reduced Fos expression in the tuberomammillary nuclei. Thus, thalidomide's hypnotic effect seems to share some downstream mechanisms with general anesthetics and GABAA-activating sedatives but does not involve the teratogenic CRBN-mediated ubiquitin/proteasome pathway.

Discovery of CRBN as a target of thalidomide: a breakthrough for progress in the development of protein degraders.

Progress in strategies aimed at breaking down therapeutic target proteins has led to a paradigm shift in drug discovery. Thalidomide and its derivatives are the only protein degraders currently used in clinical practice. Our understanding of the molecular mechanism of action of thalidomide and its derivatives has advanced dramatically since the identification of cereblon (CRBN) as their direct target. The binding of thalidomide derivatives to CRBN, a substrate recognition receptor for Cullin 4 RING E3 ubiquitin ligase (CRL4), induces the recruitment of non-native substrates to CRL4CRBN and their subsequent degradation. This discovery was a breakthrough in the current rapid development of protein-degrading agents because clarification of the mechanism of action of thalidomide derivatives has demonstrated the clinical value of these compounds. This review provides an overview of the mechanism of action of thalidomide and its derivatives and describes perspectives for protein degraders.

Myeloma Microenvironmental TIMP1 Induces the Invasive Phenotype in Fibroblasts to Modulate Disease Progression.

Tissue inhibitors of metalloproteinases (TIMPs) are endogenous matrix metalloproteinase inhibitors. TIMP1 is produced by cancer cells and has pleiotropic activities. However, its role and source in multiple myeloma (MM) are unclear. Here, we evaluated TIMP1 protein and mRNA levels in bone marrow (BM) plasma cells and assessed the effects of TIMP1 expression on fibroblast invasive capacity using three-dimensional spheroid cell invasion assays. TIMP1 mRNA and protein levels were elevated when patients progressed from monoclonal gammopathy of undetermined significance or smouldering myeloma to MM. Furthermore, TIMP1 levels decreased at complete response and TIMP1 protein levels increased with higher international staging. TIMP1 mRNA levels were markedly higher in extramedullary plasmacytoma and MM with t(4;14). Overall survival and post-progression survival were significantly lower in MM patients with high TIMP1 protein. Recombinant TIMP1 did not directly affect MM cells but enhanced the invasive capacity of fibroblasts; this effect was suppressed by treatment with anti-TIMP1 antibodies. Fibroblasts supported myeloma cell invasion and expansion in extracellular matrix. Overall, these results suggested that MM-derived TIMP1 induces the invasive phenotype in fibroblasts and is involved in disease progression. Further studies are required to elucidate the specific roles of TIMP1 in MM and facilitate the development of novel therapies targeting the TIMP1 pathway.

[Coagulative complete remission following early gastric cancer resection in a patient with steroid-resistant acquired hemophilia A and nephrotic syndrome].

During laparoscopic cholecystectomy, an 89-year-old man was discovered to have a prolonged APTT. He was transferred to our hospital for a thorough examination because wound bleeding necessitated a reoperation. Based on coagulation factor VIII activity (FVIII:C) of 3.6% and FVIII inhibitor levels of 48.5 BU/ml, he was diagnosed with acquired hemophilia A (AHA). Due to concerns about his advanced age and postoperative infection, immunosuppressive therapy with prednisolone 0.5 mg/kg/day was initiated. His clinical course was favorable, except hemorrhagic shock caused by intramuscular hemorrhage on the right back, although low FVIII inhibitor levels persisted for more than a month; additionally, lower leg edema and increased urinary protein were also observed. He was diagnosed as with AHA and secondary nephrotic syndrome, possibly because of early gastric cancer. As a result, radical endoscopic submucosal dissection (ESD) was performed while a recombinant coagulation factor VIIa preparation was administered. AHA improved rapidly following ESD, and coagulative remission was achieved. Simultaneously, the nephrotic syndrome improved. Because the control of malignant tumors may improve the status of AHA, the timing of malignant tumor intervention must be considered considering the risk of bleeding and infection associated with immunosuppression.

[Acquired hemophilia A that developed after BNT162b2 mRNA COVID-19 vaccination and worsened following re-vaccination].

An 86-year-old Japanese male patient visited a nearby hospital with painful swelling in his left upper and lower limbs 35 days after the second dose of the BNT162b2 mRNA coronavirus disease-2019 (COVID-19) vaccine. He was referred to our hematological department due to a prolonged activated partial thromboplastin time and was urgently admitted. He was diagnosed with acquired hemophilia A (AHA) based on factor VIII (FVIII) activity of 1.7%, FVIII inhibitor of 152.3 BU/ml, and FVIII-binding antibodies detected by enzyme-linked immunosorbent assay. Immunosuppressive therapy with prednisolone (PSL) at 0.5 mg/kg/day was started owing to the risk of infection due to old age and poor activities of daily living. Hemostasis treatment with bypass hemostatic preparations (rFVIIa preparation, FVIIa/FX) was administered for each bleeding event, such as intramuscular and knee joint bleeding, resulting in good hemostatic effects. Coagulative complete remission was achieved on day 69 with PSL treatment; however, FVIII activity decreased with PSL tapering. AHA relapse with rectus abdominis muscle hematoma was observed after the third vaccination. This is the first Japanese report of AHA after COVID-19 vaccination and the world's first case, in which the presence of anti-FVIII-binding antibodies were observed.

Two-year outcomes of tirabrutinib monotherapy in Waldenström's macroglobulinemia.

The phase II study of tirabrutinib monotherapy at a daily dose of 480 mg under fasting conditions for treatment-naïve and relapsed/refractory Waldenström's macroglobulinemia (ONO-4059-05 study) demonstrated a promising efficacy and tolerable safety profile. We conducted an unplanned analysis with a median follow-up of 24.8 months to update the efficacy and safety results and to report patient-reported quality of life. Of 27 enrolled patients, 22 patients continued receiving the study drug. The major response assessed by an independent review committee was observed in 25 patients (93%), including one and five patients who newly achieved complete response and very good partial response, respectively, after the primary analysis. The progression-free and overall survival rates at 24 months were 92.6% and 100%, respectively. Serum IgM levels in all patients except one declined and were maintained at low levels, although transient increases occurred after temporal interruption of the study drug. The disease-related symptoms including recurrent fever and hyperviscosity mostly disappeared. Health-related quality of life, assessed by cancer-specific questionnaires, was mostly maintained. Grade 3-4 neutropenia, lymphopenia, and leukopenia were newly recognized in three, two, and one patient, respectively. Grade 3 treatment-related hypertriglyceridemia was also recognized. Nine patients experienced grade 1-2 bleeding events (33%), one patient experienced grade 2 treatment-related atrial fibrillation, and one patient experienced grade 1 treatment-related hypertension. Treatment-related skin adverse events were observed in 14 patients (52%). Taken together, tirabrutinib has durable efficacy with an acceptable safety profile for treatment-naïve and refractory/relapsed Waldenström's macroglobulinemia.

Aromatase is a novel neosubstrate of cereblon responsible for immunomodulatory drug-induced thrombocytopenia.

Immunomodulatory drugs (IMiDs) are key agents for the treatment of multiple myeloma and myelodysplastic syndrome with chromosome 5q deletion. IMiDs exert their pleiotropic effects through the recruitment of neosubstrates to cereblon, a substrate receptor of the E3 ubiquitin ligase complex; therefore, identification of cell-specific neosubstrates is important to understand the effects of IMiDs. In clinical practice, IMiDs induce thrombocytopenia, which frequently results in the discontinuation of IMiD treatment. In the current study, we sought to identify the molecular mechanism underlying thrombocytopenia induced by IMiD treatment. We found that IMiDs strongly impaired proplatelet formation, a critical step in functional platelet production, through the inhibition of autocrine estradiol signaling in human megakaryocytes. Furthermore, we identified aromatase, an indispensable enzyme for estradiol biosynthesis, as a novel neosubstrate of cereblon. IMiDs promoted the recruitment of aromatase to cereblon, resulting in the degradation of aromatase in a proteasome-dependent manner. Finally, aromatase was significantly degraded in the bone marrow of patients with multiple myeloma who developed thrombocytopenia with IMiD treatment. These data suggest that aromatase is a neosubstrate of cereblon that is responsible for IMiD-induced thrombocytopenia.