Negative impact of immunoparesis in response to anti-SARS-CoV-2 mRNA vaccination of patients with multiple myeloma.

Multiple myeloma reduces cellular and humoral immunity. Optimal prediction of antibody response to anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine in patients with MM and related disorders is essential to prevent coronavirus disease 2019 (COVID-19) during the SARS-CoV-2 pandemic. This study analyzed the humoral response to the anti-SARS-CoV-2 messenger ribonucleic acid (mRNA) vaccine and its associated factor in 83 patients from June to November 2021 at seven member institutions of the Kyoto Clinical Hematology Study Group. SARS-CoV-2 neutralizing antibody (nAb) was measured from 12 to 210 days. The result revealed that 40 (48.2%) patients with MM and 59 (100%) healthy controls became seropositive after vaccination. Receiver operating characteristic curve analysis identified serum immunoglobulin (Ig) M of > 18 mg/dL at vaccination as the optimal threshold level associated with seropositivity in the whole cohort. Moreover, the multivariate analysis identified serum IgM of > 18 mg/dL as the independent predictor for a favorable response. Serum IgA level was positively associated with vaccine response in a sub-cohort. Our findings indicate a significant association between immunoparesis and impaired humoral response against mRNA vaccination, including that against SARS-CoV-2, and that serum non-M-protein Ig levels can serve as surrogate biomarkers of nAb production ability.

Impact of cytogenetic abnormalities in symptomatic multiple myeloma; a Japanese real-world analysis from Kansai Myeloma Forum.

To evaluate the specific prognostic value of CAs, we conducted an analysis of 923 symptomatic multiple myeloma patients. Among this cohort, 480 patients had complete data set of high-risk CAs by interphase fluorescent in situ hybridization at diagnosis. In the high-risk group analysis, the median OS of patients without CAs (n = 338, 72 %) was 6.5 years, patients with del(17p) (n = 42, 9 %) was 4.4 years, patients with t(4;14) or t(14;16) (n = 72, 15 %) was 4.4 years, and patients with double-positive CAs(del(17p) and t(4;14) or t(14;16)) (n = 18, 4 %) was 2.1 years (p = 0.032). Patients with double-positive CAs had a significantly worse prognosis.

Efficacy of elotuzumab for multiple myeloma in reference to lymphocyte counts and kappa/lambda ratio or B2 microglobulin.

Novel therapeutic drugs have dramatically improved the overall survival of patients with multiple myeloma. We sought to identify the characteristics of patients likely to exhibit a durable response to one such drug, elotuzumab, by analyzing a real-world database in Japan. We analyzed 179 patients who underwent 201 elotuzumab treatments. The median time to next treatment (TTNT) with the 95% confidence interval was 6.29 months (5.18-9.20) in this cohort. Univariate analysis showed that patients with any of the following had longer TTNT: no high risk cytogenic abnormalities, more white blood cells, more lymphocytes, non-deviated κ/λ ratio, lower ß2 microglobulin levels (B2MG), fewer prior drug regimens, no prior daratumumab use and better response after elotuzumab treatment. A multivariate analysis showed that TTNT was longer in patients with more lymphocytes (≥ 1400/µL), non-deviated κ/λ ratio (0.1-10), lower B2MG (< 5.5 mg/L) and no prior daratumumab use. We proposed a simple scoring system to predict the durability of the elotuzumab treatment effect by classifying the patients into three categories based on their lymphocyte counts (0 points for ≥ 1400/µL and 1 point for < 1400/µL) and κ/λ ratio (0 points for 0.1-10 and 1 point for < 0.1 or ≥ 10) or B2MG (0 points for < 5.5 mg/L and 1 point for ≥ 5.5 mg/L). The patients with a score of 0 showed significantly longer TTNT (p < 0.001) and better survival (p < 0.001) compared to those with a score of 1 or 2. Prospective cohort studies of elotuzumab treatment may be needed to validate the usefulness of our new scoring system.

Impact of Treatment with Anti-CD20 Monoclonal Antibody on the Production of Neutralizing Antibody Against Anti-SARS-CoV-2 Vaccination in Mature B-Cell Neoplasms.

Background and Purpose: Anti-CD20 monoclonal antibodies (MoAbs), rituximab (RIT), and obinutuzumab (OBZ) are the central components of immunochemotherapy for B-cell lymphoma (BCL). However, these agents potentially cause B-cell depletion, resulting in the impairment of antibody (Ab) production. During the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic, the optimal prediction of Ab response against anti-SARS-CoV-2 vaccination is critically important in patients with BCL treated by B-cell depletion therapeutics to prevent coronavirus disease 2019 (COVID-19). Patients and Methods:  We investigated the effect of using RIT and/or OBZ on the Ab response in 131 patients with various types of BCL who received the second SARS-CoV-2 mRNA vaccine either after, during, or before immunochemotherapy containing B-cell-depleting moiety between June and November 2021 at seven institutes belonging to the Kyoto Clinical Hematology Study Group. The SARS-Cov-2 neutralizing Ab (nAb) was measured from 14 to 207 days after the second vaccination dose using the iFlash3000 automatic analyzer and the iFlash-2019-nCoV Nab kit. Results: Among 86 patients who received the vaccine within 12 months after B-cell depletion therapy, 8 (9.3%) were seropositive. In 30 patients who received the vaccine after 12 months from B-cell depletion therapy, 22 (73%) were seropositive. In 15 patients who were subjected to B-cell depletion therapy after vaccination, 2 (13%) were seropositive. The multivariate analysis indicated that an interval of 12 months between B-cell depletion therapy and the subsequent vaccination was significantly associated with effective Ab production. Receiver operating characteristic curve analysis identified the optimal threshold period after anti-CD20 MoAb treatment, which determines the seropositivity against SARS-CoV-2, to be 342 days. Conclusion: The use of anti-CD20 MoAb within 12 months before vaccination is a critical risk for poor Ab response against anti-SARS-CoV-2 vaccination in patients with BCL.

Watchful waiting is an acceptable treatment option for asymptomatic primary ocular adnexal mucosa-associated lymphoid tissue lymphoma: A retrospective study.

BACKGROUND: Primary ocular adnexal mucosa-associated lymphoid tissue (MALT) lymphoma (POAML) is the most common subtype of indolent ocular adnexal lymphomas. Although radiotherapy (RT) is the standard of care for localized POAML, it can occasionally lead to permanent side effects. Other treatment strategies, such as rituximab (R) monotherapy and immunochemotherapy, have been used for POAML treatment, but their long-term benefits and relative merits remain unclear. While watchful waiting (WW) is a potential option for some indolent lymphomas, the benefits of WW for POAML patients are also unclear. METHODS: We here retrospectively analyzed 75 patients who were diagnosed with POAML between 2008 and 2019 in the institutions of the Kyoto Clinical Hematology Study Group. RESULTS: Commonly involved sites were conjunctiva (42.7%), orbit (36.0%), and lacrimal gland (12.0%), and most patients (92.0%) presented with Ann Arbor stage IE disease. The treatment strategy was selected at the physicians' discretion. More patients without subjective symptoms by tumor mass were subjected to WW (29 patients), while more patients with tumor-derived subjective symptoms were treated by tumor-directed therapy (24 received focal RT, and 19 received R monotherapy). Complete response rates were 79.2% and 42.1% in the RT and R groups, respectively. At 60 months of follow-up, the estimated proportions of POAML patients not requiring new treatment were 69.4%, 85.2%, and 53.8% in the WW, RT, and R groups, respectively. There were no significant differences in the time to start a new treatment between WW and RT groups (median: both not reached [NR], p = 0.187) and between WW and R groups (median: NR vs. 69.0 months, p = 0.554). No specific predictive factor for the future need of treatment was identified in the WW group. CONCLUSION: Our results demonstrate WW may be an acceptable treatment option for POAML, especially for asymptomatic patients.

Monocyte or white blood cell counts and ß2 microglobulin predict the durable efficacy of daratumumab with lenalidomide.

Background: Daratumumab is one of the most widely used treatments for relapsed/refractory multiple myeloma (MM) patients. However, not all patients achieve a lasting therapeutic response with daratumumab. Objectives: We hypothesized that a durable response to daratumumab could be predicted by the balance between the MM tumor burden and host immune status. Design: We conducted a retrospective study using the real-world data in the Kansai Myeloma Forum (KMF) database. Methods: We retrospectively analyzed 324 relapsed/refractory MM patients who were treated with daratumumab in the KMF database. Results: In this study, 196 patients were treated with daratumumab, lenalidomide, and dexamethasone (DLd) regimen and 128 patients were treated with daratumumab, bortezomib, and dexamethasone (DBd) regimen. The median age at treatment, number of prior treatment regimens and time-to-next-treatment (TTNT) were 68, 4 and 8.02 months, respectively. A multivariate analysis showed that the TTNT under the DLd regimen was longer with either higher monocyte counts (analysis 1), higher white blood cell (WBC) counts (analysis 2), lower ß2 microglobulin (B2MG < 5.5 mg/L) or fewer prior regimens (<4). No parameters were correlated with TTNT under the DBd regimen. Conclusion: We propose a simple scoring model to predict a durable effect of the DLd regimen by classifying patients into three categories based on either monocyte counts (0 points for ⩾200/µl; 1 point for <200/µl) or WBC counts (0 points for ⩾3500/µl; 1 point for <3500/µl) plus B2MG (0 points for <5.5 mg/L; 1 point for ⩾5.5 mg/L). Patients with a score of 0 showed significantly longer TTNT and significantly better survival compared to those with a score of 1 or 2 (both p < 0.001). To confirm this concept, our results will need to be validated in other cohorts.

Pretreatment serum level of interleukin-6 predicts carfilzomib-induced hypertension in relapsed/refractory multiple myeloma.

Carfilzomib (CFZ) constitutes powerful combinatory therapy for relapsed/refractory multiple myeloma (RRMM); however, cardiovascular adverse events (CVAEs) have been shown as major treatment obstacles with the use of CFZ. Along with our multi-institutional prospective observational study by the Kyoto Clinical Hematology Study Group on the efficacy and safety of CFZ-based treatments (UMIN000025108), we here performed an ad hoc analysis of CFZ-related CVAEs in 50 patients with RRMM. We analyzed the association between CFZ-related CVAEs and pre-planned examinations, including patients' background, electrocardiographic findings, echocardiographic findings, and serum/plasma levels of 18 potential candidate biomarkers. The common CVAEs were hypertension (42%), arrhythmia (14%), and prolongation of QT corrected interval (10%), whereas no serious CVAEs occurred. The pretreatment serum level of interleukin-6 was identified as a significant risk factor for CFZ-related hypertension. This study revealed hypertension as the most frequent CFZ-related CVAE and suggested that baseline serum interleukin-6 is a useful predictor for CFZ-induced hypertension.

Clinical impacts of frailty, poor performance status, and advanced age in carfilzomib-containing treatment for relapsed/refractory multiple myeloma: post hoc investigation of the KOTOSG multicenter pilot prospective observational study.

We conducted a post hoc analysis of our previous pilot observational study on the efficacy and safety of carfilzomib (CFZ)-containing therapy in 50 patients with relapsed/refractory multiple myeloma in routine practice to clarify the relationships between three major criteria for vulnerability (frailty, poor performance status [PS], and advanced age [≥ 75 years]) and their clinical impact on efficacy and adverse events (AEs). Sixteen patients fulfilled at least one and five patients fulfilled all three criteria. The overall response rate was not significantly affected by frailty, poor PS, and/or advanced age; however, frailty and advanced age were significantly associated with shorter progression-free survival (PFS). In contrast, no significant difference in PFS was observed between patients with PS0-1 or PS2-4. The three criteria for vulnerability were associated with more frequent hematologic AEs: frailty, poor PS, and/or advanced age significantly increased the risk of grade 3-4 anemia and lymphopenia. However, these criteria were not associated with increased risk of other non-hematologic AEs except infection. Collectively, these results demonstrate the need to carefully manage severe hematologic AEs in vulnerable patients and perform disease-specific assessment of frailty to predict prognosis.

Prognostic impact of resistance to bortezomib and/or lenalidomide in carfilzomib-based therapies for relapsed/refractory multiple myeloma: The Kyoto Clinical Hematology Study Group, multicenter, pilot, prospective, observational study in Asian patients.

BACKGROUND: Combinatory strategies with carfilzomib (CFZ), a second-generation proteasome inhibitor, plus dexamethasone (DEX) with or without lenalidomide (LEN) have shown promising efficacy for patients with relapsed/refractory multiple myeloma (RRMM) in pivotal clinical trials. However, their effects on patients who were resistance to bortezomib (BTZ) and/or LEN have not been fully evaluated in a daily practice setting. AIMS: To evaluate the real-world efficacy and safety of CFZ-based treatments; that is, CFZ with LEN plus DEX (KRD therapy) and CFZ with DEX (KD therapy), in Asian patients, we conducted a multicenter pilot prospective observational study in the Kyoto Clinical Hematology Study Group. METHODS AND RESULTS: All 50 patients with RRMM enrolled in this study were treated with CFZ-based treatments between 2017 and 2019. KRD and KD were administered to 31 and 19 patients, respectively. The overall response rates (ORRs) were 80.6% with KRD and 73.7% with KD. Two-year progression-free survival (PFS) and overall survival (OS) were 58.5% and 79.7% with KRD, and 23.1% and 52.6% with KD. By multivariate analysis, refractoriness to BTZ and to LEN were identified as independent unfavorable factors for both PFS and OS. The common non-hematologic AEs included hypertension (42.0%), fever (24.0%), fatigue (24.0%), and infection (16.0%). No serious heart failure was observed. This study is registered as UMIN000025108. CONCLUSION: This study suggests the need of the development of novel CFZ-containing strategy which can overcome the refractoriness to BTZ and/or LEN, while both KRD and KD were shown to be mostly feasible in Asian patients in a daily practice setting.

Retrospective analysis of plasmacytoma in Kansai Myeloma Forum Registry.

We retrospectively analyzed 51 patients with solitary plasmacytoma diagnosed from October 2002 to September 2018 from a cohort of 3575 patients with plasma cell dyscrasias registered in the Kansai Myeloma Forum. Twenty-seven patients had solitary bone plasmacytoma (SBP) and 24 had extramedullary plasmacytoma (EMP), with prevalence of 0.8% and 0.7%, respectively. The most frequent M protein was IgG (40%) in SBP, whereas non-secretory proteins were most frequent (50%) in EMP. Five-year overall survival was 78.2% in SBP and 80.8% in EMP (P = 0.894). Among patients with SBP, 44% progressed to MM with a median time of 10.5 months (2.4-93.3 months), whereas 8% of EMP patients progressed to MM with a median time of 18.6 months (13.0-24.2 months). The most frequent treatment was radiotherapy (41%) or observation (41%) in SBP, and chemotherapy (54%) in EMP. No statistically significant difference was observed upon univariate analysis of prognostic factors including age, sex, performance status, and IgG M protein. Our results suggest that there are biological differences between SBP and EMP in real-world settings.

Current status of periodontal disease in adults in Takahagi, Japan: a cross-sectional study.

BACKGROUND: To date, a few studies have documented the detailed periodontal conditions of a Japanese population. It is important to know if the awareness of Japanese nationals and dentists regarding oral hygiene and prevention of periodontal disease have improved when compared with the past in Japan for the development of future scenarios regarding prevention. The aim of this study was to investigate the severity, prevalence, and extent of periodontal disease in the adult population of the city of Takahagi, Japan. Results were also compared with those of an epidemiological study performed in Japan in the 1980s. METHODS: A total of 582 (aged 20 to 89 years) randomly sampled Takahagi residents answered a comprehensive questionnaire and participated in clinical examinations. RESULTS: The mean percentages of tooth surfaces harboring plaque and exhibiting BOP were 59.5 ± 20.9% and 31.1 ± 21.1%, respectively. The mean PPD and CAL were 2.5 ± 0.5 mm and 2.9 ± 1.0 mm, respectively. Compared with results of the 1980s survey, the mean percentages of plaque and bleeding on probing were lower in the current population. The mean CAL and prevalence of attachment loss of ≥5 mm in some age groups were higher in the present study than in the 1980s study. There were no statistically significant differences with respect to mean probing depth between the 1980s and current age groups. CONCLUSIONS: Periodontal disease was still prevalent in the current Japanese population, even though some improvement occurred. Proper public health programs therefore need to be established.

Sequential therapy of four cycles of bortezomib, melphalan, and prednisolone followed by continuous lenalidomide and dexamethasone for transplant-ineligible newly diagnosed multiple myeloma.

The combinations of melphalan, bortezomib, and prednisolone (VMP) and of lenalidomide and dexamethasone (Rd) are standard treatment strategies for transplant-ineligible newly diagnosed multiple myeloma (NDMM). To make the most of these two strategies, we investigated the efficacy and feasibility of first-line treatment with 4 cycles of VMP followed by continuous Rd therapy in a multi-institutional phase 2 study in Japanese patients with transplant-ineligible NDMM. Thirty-six patients of median age 74 years old with NDMM initially received 35-day cycles of VMP: oral melphalan (6 mg/m2) and prednisolone (60 mg/m2) on days 1 to 4 and bortezomib (1.3 mg/m2) on days 1, 8, 15, and 22. After 4 cycles of VMP, treatment was switched to 28-day cycles of Rd, which was continued until disease progression or emergence of an unacceptable adverse event (AE) in 33 patients, while one patient who achieved CR after VMP continued VMP at the physician's discretion. The overall response rates after VMP and after Rd were 66.7% and 86.1%, including CR rates of 5.6% and 36.1%, respectively. In a median follow-up period of 34.3 months, the progression-free survival and overall survival rates at 3 years were 43.2% and 81.3%, respectively. Grade 3-4 hematological AEs included neutropenia (39% with VMP and 24% with Rd) and thrombocytopenia (11% with VMP and 3% with Rd). There was no death due to an AE. In conclusion, sequential therapy with VMP followed by Rd is effective and mostly feasible for transplant-ineligible NDMM. The study is registered as UMIN000034815.

Reproductive interference by alien hornet Vespa velutina threatens the native populations of Vespa simillima in Japan.

The yellow-legged hornet Vespa velutina has become one of the major alien species in European and East Asian countries. As in its homeland, the invading V. velutina is reported as the major predator of honeybees and is becoming a threat to beekeeping in Europe. However, it remains unknown how V. velutina might affect native hornets when it invades Asia, where a large number of Vespa species are distributed. Thus, by analyzing the mitochondrial cytochrome c oxidase subunit I gene, we investigated whether interspecific mating occurs between V. velutina and Japanese native Vespa spp. Our results showed that the alien V. velutina causes reproductive interference in Japanese native hornet Vespa simillima. Forty-three percent of native V. simillima queens had the sperm of V. velutina males, and among the all V. simillima queens analyzed, 28% only had V. velutina sperm. We did not find evidence of V. velutina queens having the sperm of V. simillima males. These findings suggest that reproductive interference by V. velutina males poses a threat to the native V. simillima populations. A decline of V. simillima may also negatively affect other insects that interact with V. simillima.

Immunosuppressive therapy with rabbit antithymocyte globulin therapy for acquired aplastic anemia: a multi-institutional retrospective study in Japanese adult patients.

We retrospectively analyzed efficacy and safety of therapy with rabbit antithymocyte globulin (rATG) in combination with cyclosporine A (CsA) in 30 Japanese adult patients with acquired aplastic anemia (AA) in the Kyoto Clinical Hematology Study Group. The median observation period was 31 months and the median age of the patients was 54 years. The objective response rates (ORRs) to rATG plus CsA increased over time until 18 months after the start of treatment; the rate of achievement of better than partial response at 18 months was 66.7%. The 2-year overall survival (OS) rate was 79% in all patients. In eight patients aged ≥ 75 years old, the ORR was 62.5% and the 2-year OS rate of 50% was not significantly inferior to that in patients aged ≤ 74 years old. The overall mortality rate was 16.7% in our cohort, while the mortality rate in patients aged ≥ 75 years old was 37.5%, which was higher than that in patients aged ≤ 74 years old (9.1%), although the difference was not statistically significant. Collectively, rATG combined with CsA is an effective and feasible treatment for AA, while patients should be appropriately selected.

Complete mitochondrial DNA sequence of the alien hornet Vespa velutina (Insecta: Hymenoptera) invading Kyushu Island, Japan.

We analyzed the complete mitochondrial genome of the invasive Asian hornet Vespa velutina from Kyushu Island, Japan. The mitochondrial genome of V. velutina was identified as a circular molecule of 16,388 bp. We predicted that the genome contains 13 protein-coding genes (PCGs), 22 tRNA genes, and 2 rRNA genes, along with one A + T-rich control region. The average AT content is 81.68%. Molecular phylogenetic analysis using the 13 mitochondrial PCGs from 11 closely related taxa of Vespidae indicated that the V. velutina invading the Japanese Islands of Kyushu and Tsushima have a common origin.

Functional electrical stimulation to the abdominal wall muscles synchronized with the expiratory flow does not induce muscle fatigue.

[Purpose] Continuous electrical stimulation of abdominal wall muscles is known to induce mild muscle fatigue. However, it is not clear whether this is also true for functional electrical stimulation delivered only during the expiratory phase of breathing. This study aimed to examine whether or not intermittent electrical stimulation delivered to abdominal wall muscles induces muscle fatigue. [Subjects and Methods] The subjects were nine healthy adults. Abdominal electrical stimulation was applied for 1.5 seconds from the start of expiration and then turned off during inspiration. The electrodes were attached to both sides of the abdomen at the lower margin of the 12th rib. Abdominal electrical stimulation was delivered for 15 minutes with the subject in a seated position. Expiratory flow was measured during stimulus. Trunk flexor torque and electromyography activity were measured to evaluate abdominal muscle fatigue. [Results] The mean stimulation on/off ratio was 1:2.3. The declining rate of abdominal muscle torque was 61.1 ± 19.1% before stimulus and 56.5 ± 20.9% after stimulus, not significantly different. The declining rate of mean power frequency was 47.8 ± 11.7% before stimulus and 47.9 ± 10.2% after stimulus, not significantly different. [Conclusion] It was found that intermittent electrical stimulation to abdominal muscles synchronized with the expiratory would not induce muscle fatigue.

Complete mitochondrial DNA sequence of the invasive hornet Vespa velutina (Insecta, Hymenoptera) found in Japan.

In this study, we analyzed the complete mitochondrial genome of the invasive Asian hornet Vespa velutina from Japan. The mitochondrial genome of V. velutina was identified as a circular molecule of 16,765 bp, similar to that in other hornet species. It was predicted to contain 13 protein-coding, 20 tRNA, and two rRNA genes, along with one A + T-rich control region. The initiation codons ATC was found in one, ATG in four, ATT in five, and ATA in three genes, while TAA was the termination codon in all these genes. The average AT content of 13 protein-coding was 82%.

High-speed atomic force microscopy reveals structural dynamics of amyloid ß1-42 aggregates.

Aggregation of amyloidogenic proteins into insoluble amyloid fibrils is implicated in various neurodegenerative diseases. This process involves protein assembly into oligomeric intermediates and fibrils with highly polymorphic molecular structures. These structural differences may be responsible for different disease presentations. For this reason, elucidation of the structural features and assembly kinetics of amyloidogenic proteins has been an area of intense study. We report here the results of high-speed atomic force microscopy (HS-AFM) studies of fibril formation and elongation by the 42-residue form of the amyloid ß-protein (Aß1-42), a key pathogenetic agent of Alzheimer's disease. Our data demonstrate two different growth modes of Aß1-42, one producing straight fibrils and the other producing spiral fibrils. Each mode depends on initial fibril nucleus structure, but switching from one growth mode to another was occasionally observed, suggesting that fibril end structure fluctuated between the two growth modes. This switching phenomenon was affected by buffer salt composition. Our findings indicate that polymorphism in fibril structure can occur after fibril nucleation and is affected by relatively modest changes in environmental conditions.

Phenolic compounds prevent the oligomerization of α-synuclein and reduce synaptic toxicity.

Lewy bodies, mainly composed of α-synuclein (αS), are pathological hallmarks of Parkinson's disease and dementia with Lewy bodies. Epidemiological studies showed that green tea consumption or habitual intake of phenolic compounds reduced Parkinson's disease risk. We previously reported that phenolic compounds inhibited αS fibrillation and destabilized preformed αS fibrils. Cumulative evidence suggests that low-order αS oligomers are neurotoxic and critical species in the pathogenesis of α-synucleinopathies. To develop disease modifying therapies for α-synucleinopathies, we examined effects of phenolic compounds (myricetin (Myr), curcumin, rosmarinic acid (RA), nordihydroguaiaretic acid, and ferulic acid) on αS oligomerization. Using methods such as photo-induced cross-linking of unmodified proteins, circular dichroism spectroscopy, the electron microscope, and the atomic force microscope, we showed that Myr and RA inhibited αS oligomerization and secondary structure conversion. The nuclear magnetic resonance analysis revealed that Myr directly bound to the N-terminal region of αS, whereas direct binding of RA to monomeric αS was not detected. Electrophysiological assays for long-term potentiation in mouse hippocampal slices revealed that Myr and RA ameliorated αS synaptic toxicity by inhibition of αS oligomerization. These results suggest that Myr and RA prevent the αS aggregation process, reducing the neurotoxicity of αS oligomers. To develop disease modifying therapies for α-synucleinopathies, we examined effects of phenolic compounds on α-synuclein (αS) oligomerization. Phenolic compounds, especially Myricetin (Myr) and Rosmarinic acid (RA), inhibited αS oligomerization and secondary structure conversion. Myr and RA ameliorated αS synaptic toxicity on the experiment of long-term potentiation. Our results suggest that Myr and RA prevent αS aggregation process and reduce the neurotoxicity of αS oligomers. Phenolic compounds are good candidates of disease modifying drugs for α-synucleinopathies.