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Background Prospective data on the risk of recurrence among women with hormone receptor-positive early breast cancer who temporarily discontinue endocrine therapy to attempt pregnancy are lacking. Methods We conducted a single-group trial in which we evaluated the temporary interruption of adjuvant endocrine therapy to attempt pregnancy in young women with previous breast cancer. Eligible women were 42 years of age or younger; had had stage I, II, or III disease; had received adjuvant endocrine therapy for 18 to 30 months; and desired pregnancy. The primary end point was the number of breast cancer events (defined as local, regional, or distant recurrence of invasive breast cancer or new contralateral invasive breast cancer) during follow-up. The primary analysis was planned to be performed after 1600 patient-years of follow-up. The prespecified safety threshold was the occurrence of 46 breast cancer events during this period. Breast cancer outcomes in this treatment-interruption group were compared with those in an external control cohort consisting of women who would have met the entry criteria for the current trial. Results Among 516 women, the median age was 37 years, the median time from breast cancer diagnosis to enrollment was 29 months, and 93.4% had stage I or II disease. Among 497 women who were followed for pregnancy status, 368 (74.0%) had at least one pregnancy and 317 (63.8%) had at least one live birth. In total, 365 babies were born. At 1638 patient-years of follow-up (median follow-up, 41 months), 44 patients had a breast cancer event, a result that did not exceed the safety threshold. The 3-year incidence of breast cancer events was 8.9% (95% confidence interval [CI], 6.3 to 11.6) in the treatment-interruption group and 9.2% (95% CI, 7.6 to 10.8) in the control cohort. Conclusions Among select women with previous hormone receptor-positive early breast cancer, temporary interruption of endocrine therapy to attempt pregnancy did not confer a greater short-term risk of breast cancer events, including distant recurrence, than that in the external control cohort. Further follow-up is critical to inform longer-term safety. (Funded by ETOP IBCSG Partners Foundation and others; POSITIVE ClinicalTrials.gov number, NCT02308085.).

Background The risk of ipsilateral breast tumor recurrence (IBTR) and the prognostic outcome of breast-conserving surgery (BCS) for germline BRCA1/2 pathogenic variant (BRCA1/2+) carriers remain controversial. We examined differences in IBTR and prognosis between BRCA1/2+ carriers and non-carriers following BCS for breast cancer. Methods Clinical and pathological data were collected by retrospectively reviewing charts of consecutive patients with stage 0-III breast cancer who underwent genetic testing for germline BRCA1/2 and BCS between 1996 and 2020. Patients with variants of breast cancer-associated genes other than BRCA1/2 were excluded. We compared the incidence of IBTR and prognosis, including overall survival (OS), breast cancer-specific survival (BCSS), and distant recurrence-free survival (DRFS), between BRCA1/2+ carriers and non-carriers. Results We analyzed 551 patients (587 breasts with cancer), including 30 BRCA1+ carriers (32 breasts) and 31 BRCA2+ carriers (32 breasts). The median follow-up was 5.8 years (7.2 and 5.3 years for carriers and non-carriers, respectively). The median age at breast cancer diagnosis was 43 and 46 years for carriers and non-carriers, respectively, indicating younger onset of cancer in carriers (age ≤ 40 years; 46.9% for carriers vs. 27.5% for non-carriers, p = 0.001). In carriers, breast cancer more frequently expressed estrogen receptor-negative (56.2% for BRCA1+ carriers and 15.6% for BRCA2+ carriers vs. 22.0% for non-carriers, p = 0.013), progesterone receptor-negative (62.5% for BRCA1+ carriers and 31.3% for BRCA2+ carriers vs. 29.5%, p = 0.005), nuclear grade III (45.3% for carriers vs. 29.5% for non-carriers, p = 0.010), or a higher Ki-67 index (Ki-67 index > 20) (89.5% vs. 61.8%, p = 0.001) than non-carriers. Moreover, carriers underwent chemotherapy more frequently than non-carriers (62.5% vs. 42.4%, p = 0.002). Cancer stage, tumor size, HER2 status, presence of lymphovascular invasion, and the rate of positive or close surgical margins did not statistically differ between the examined groups. No statistical differences were detected in the number of patients who underwent whole-breast radiotherapy following BCS: 59 breasts in carriers and 503 in non-carriers (92.2% vs. 96.4%). During follow-up, we noted that 9 breasts of BRCA1/2+ carriers (5 [15.6%] for BRCA1+ and 4 [12.5%] for BRCA2+) and 35 breasts (6.7%) of non-carriers developed IBTR (p = 0.035). In an analysis excluding patients who did not undergo radiotherapy, the rate of IBTR remained significantly higher in BRCA1/2+ carriers (p = 0.034) than that in non-carriers. The median time to IBTR was 10.2 years in carriers (10.2 years for BRCA1+ and 8.5 years for BRCA2+) and 3.5 years in non-carriers. Carriers were more likely than non-carriers to exhibit distinct subtypes of recurrent tumors in the ipsilateral breast (66.7% for carriers vs. 19.4% for non-carriers, p = 0.006), occurring in a different quadrant from the primary tumor (50.0% vs. 27.3%, p = 0.215). No significant differences in OS (p = 0.068), BCSS (p = 0.109), or DRFS (p = 0.359) were noted between carriers and non-carriers. Conclusion BRCA1/2+ carriers exhibited a higher risk of IBTR after BCS and a longer time to IBTR than non-carriers. One limitation of the present study is a longer follow-up period for carriers than for non-carriers, as carriers typically underwent long-term observation at our institution; hence, further data accumulation is warranted for validating these findings. Subtypes and quadrants of IBTR were frequently distinct in carriers, indicating the increased incidence of new primary breast cancer. Although the prognosis did not differ between carriers and non-carriers, our results suggest the necessity for long-term intensive breast surveillance of BRCA1/2+ carriers after BCS. Citation Format: Sakiko Kondo, Kumiko Kida, Misato Suzuki, Chika Fukano, Atsushi Yoshida, Naoki Hayashi, Junko Takei, Michiko Yamanaka, Hideko Yamauchi. Impact of BRCA1/2 pathogenic variants on ipsilateral breast tumor recurrence and prognosis following breast-conserving surgery [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P1-09-03.

Background: Pregnancy after breast cancer (BC) is of substantial importance for many young women at diagnosis and during follow-up. BC treatment including standard endocrine therapy (ET) (5-10 years) may reduce ovarian reserve and the chances of subsequent successful pregnancy, given conception is contraindicated during ET. A temporary interruption of ET to attempt and carry a pregnancy in this population has never been prospectively studied. Methods: POSITIVE is a single-arm, prospective, investigator-initiated, international trial evaluating the safety and pregnancy outcomes of interrupting ET for young women with early-stage hormone-receptor-positive (HR+) BC who desire pregnancy. The primary objective is to assess the risk of BC relapse associated with ET interruption for ~2 years to achieve pregnancy. Women ≤42 years with stage I-III HR+ BC who received adjuvant ET (SERM alone, GnRH analogue plus SERM or AI) for 18 to 30 months and wished to interrupt ET to attempt pregnancy were eligible. The primary endpoint is breast cancer free interval (BCFI) defined as the time from enrollment to the first BC event (local, regional, distant recurrence or a new invasive contralateral BC). Planned sample size was 500 patients. Three interim analyses of BCFI were reviewed by the Data Safety Monitoring Committee (DSMC) to assure a 95% chance of stopping the trial early if the annual BCFI event rate exceeded 4%; with primary analysis triggered after 1600 patient years of follow-up (pyfu) and no more than 46 BCFI events defined as the safety threshold. The DSMC recommended continuing the study following each interim analysis. We now report the primary results. Results: From 12/2014 to 12/2019, 518 women were enrolled. At enrollment, the median age of participants was 37 years (27-43 years); 75.0% were nulliparous, 93.4% had stage I/II disease, 66.3% node-negative. Median time from BC diagnosis to enrollment was 29 months (IQR: 25-32). Tamoxifen alone was the most prescribed ET (41.7%), followed by tamoxifen+ovarian function suppression (35.7%). 62.0% of participants had received neo/adjuvant chemotherapy. At a median follow-up of 41 months (1638 pyfu), 44 participants had experienced a BCFI event, not exceeding the pre-specified safety threshold of 46 events. The 3-year BCFI failure percent was 8.9% (95% CI: 6.3 to 11.6%), similar to the 9.2% (95% CI: 7.6 to 10.8%) calculated in the comparative external control cohort from the SOFT/TEXT trials (Sun et al, Breast 2020). Of 497 women followed for pregnancy status, 368 (74.0%) had at least one pregnancy, 317 (63.8%) had at least one live birth, with a total of 365 babies born. Based on competing risk analysis, 76.3% of patients resumed ET (half within 26 months), 8.3% had BCFI event/death before ET resumption, and 15.4% had not resumed ET yet. Conclusions: The POSITIVE trial demonstrates that for young women with early HR+ BC desiring pregnancy, temporary interruption of ET to attempt pregnancy does not confer a greater short-term risk of recurrence than that observed in a modern historical control group that did not interrupt ET. Most participants have had a live birth. Further follow-up is planned to confirm long-term safety. These results should be considered in counselling BC patients desiring future pregnancy. Citation Format: Ann Partridge, Olivia Pagani, Samuel M. Niman, Monica Ruggeri, Fedro Alessandro A. Peccatori, Hatem A. Azim, Marco Colleoni, Cristina Saura, Chikako Shimizu, Anna Saetersdal, Judith Kroep, Audrey Mailliez, Ellen Warner, Virginia F. Borges, Frédéric Amant, Andrea Gombos, Akemi Kataoka, Christine Rousset-Jablonski, Simona Borstnar, Junko Takei, Jeong Eon Lee, Janice Walshe, Manuel Ruiz Borrego, Halle Moore, Christobel Saunders, Vesna Bjelic-Radisic, Snezana Susnjar, Fatima Cardoso, Karen L. Smith, Teresa Ferreiro Vilarino, Karin Ribi, Kathryn Ruddy, Sarra El-Abed, Martine Piccart, Larissa A. Korde, Aron Goldhirsch, Richard D. Gelber. Pregnancy Outcome and Safety of Interrupting Therapy for women with endocrine responsIVE breast cancer: Primary Results from the POSITIVE Trial (IBCSG 48-14/BIG 8-13) [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr GS4-09.

BACKGROUND: BRCA1/2-associated invasive breast cancer has been extensively studied. However, there are few reports of ductal carcinoma in situ (DCIS). OBJECTIVE: This study aimed to investigate the clinicopathological and imaging findings of DCIS in patients with BRCA1/2 mutations. METHODS: This was a single-institution, retrospective study. We identified patients diagnosed with DCIS with BRCA mutations between September 2003 and December 2020. Clinicopathological data and mammography (MG), magnetic resonance imaging (MRI), and ultrasound (US) findings were reviewed. RESULTS: We identified 30 cancers in 28 patients; 7 (25.0%) patients had BRCA1 mutations, and 21 (75.0%) had BRCA2 mutations. The median patient age was 42 years. Screening was the most common reason for the detection of DCIS (50.0%), followed by occult cancer diagnosed by pathological examination after risk-reducing mastectomy (26.7%). The nuclear grade was most often 1 (46.7%), and 93.3% were estrogen and/or progesterone receptor positive. The detection rates of MG, MRI, and US were 64.3%, 72.0%, and 64.0%, respectively. The most common imaging findings were calcification (100%) on MG, non-mass enhancement (88.9%) on MRI, and hypoechoic area (75.0%) on US. CONCLUSION: BRCA-associated DCIS was more strongly associated with BRCA2, and imaging features were similar to those of sporadic DCIS. Our results are helpful in informing surveillance strategies based on genotypes in women with BRCA mutations.

Among younger patients, one of the important concerns is whether they can give birth safely. Although previous studies have investigated this topic, many aspects remain unclear owing to potential biases. We aimed to evaluate the prognostic effect of subsequent childbirth after the diagnosis using propensity score matching.A single-center retrospective cohort study was conducted. This study included patients aged ≤ 45 years, diagnosed with breast cancer between 2005 and 2014. Patients with and without subsequent childbirth were assigned to the childbirth and non-childbirth cohorts, respectively. Relapse-free survival (RFS) and overall survival (OS) of the childbirth cohort were compared with those of the non-childbirth cohort. The covariates in the propensity score model included age, tumor size, node status, number of preceding childbirths before the diagnosis, estrogen receptor, and human epidermal growth factor receptor 2 status.104 patients with childbirth and 2250 without childbirth were assigned to the respective cohorts. At a median follow-up of 82 months, the childbirth cohort showed a significantly longer RFS than the non-childbirth cohort (HR = 0.469 [0.221-0.992]; p = 0.047). There was no significant difference in the OS (HR = 0.208 [0.029-1.494]; p = 0.119). After matching, subsequent childbirth was not significantly associated with RFS (HR = 0.436 [0.163-1.164], p = 0.098) and OS (HR = 0.372 [0.033-4.134], p = 0.402).Subsequent childbirth was not associated with an increased risk of relapse and mortality. It is important to make younger patients aware of these novel findings and aid them in their decision-making.

The epidermal growth factor receptor (EGFR) contributes to tumor malignancy through gene amplification and/or protein overexpression. In our previous study, we developed an anti-human EGFR (hEGFR) monoclonal antibody (mAb), clone EMab-134 (mouse IgG

The epidermal growth factor receptor (EGFR) is involved in tumor malignancy through gene amplification and/or protein overexpression. An anti-human EGFR (hEGFR) monoclonal antibody (clone EMab-134), which explicitly detects hEGFR and dog EGFR (dEGFR), was previously developed. The defucosylated mouse IgG

Background: Radiation-induced angiosarcoma (RIAS) of the breast is a very rare disease. Previous studies from other countries have been reported that patients having RIAS has a poor prognosis, and the efficacy of chemotherapy is still controversial. However, the prognosis of RIAS and the prognostic impact of pre- or postoperative chemotherapy for RIAS in Japanese population are not well known. Our study aimed to assess them in Japanese population using publication data with the cases from our institute. Methods: We obtained 36 Japanese patients data from thirty-four original articles from 2007 to 2020 and 3 patients from our database. Clinicopathological data including age at diagnosis of RIAS, surgery for RIAS, pre- or postoperative chemotherapy for RIAS, regimen of chemotherapy, tumor size, stage for primary breast cancer, and systematic treatment for breast cancer were collected. We assessed disease-free survival (DFS), distant disease-free survival (DDFS), and overall survival (OS) using Kaplan-Meier survival curves and log rank test. Hazard ratios were estimated from Cox models. Results: The median age at diagnosis of RIAS was 73.0 years (range, 32-89 years). A median follow-up period was 22 months (range, 6-84 months). RIAS developed on the breast in 36 patients (92.3%) and on chest wall in 3 patients (7.7%). Thirty-six patients (92.3%) underwent surgery. Chemotherapy was administered to 13 cases (33.2%); preoperatively in 3 patients and postoperatively in 10 patients. All patients had received taxane-based chemotherapy. The median size of tumor in pathological examination was 43.5 mm (range, 9-100 mm). There was no difference of patient’s characteristics between patients with or without chemotherapy. The median DFS period was 14 months (range 1-75 months), and the median OS period was 22 months (range, 6-84 months). Chemotherapy in addition to surgery significantly improved DFS period (19 vs 12 months, p=0.027), and DDFS tended to be prolonged by adding chemotherapy (p=0.06). However, chemotherapy did not improved OS (p=0.878). In multivariate analysis, age ≥ 70 years and no chemotherapy for RIAS were the independent poor prognostic factors for DFS. Conclusions: Our study showed that chemotherapy might reduce recurrence rate of RIAS in Japanese patients but did not improve OS. Further studies are warranted to confirm the prognostic impact and proper regimen of chemotherapy for RIAS. Citation Format: Yuri Takehara, Naoko Matsuda, Daiki Kobayashi, Atsushi Yoshida, Junko Takei, Hiroko Tsunoda, Naoki Kanomata, Hideko Yamauchi, Naoki Hayashi. Radiation induced angiosarcoma of the breast: Chemotherapy for radiation induced angiosarcoma of the breast - An individual participant data meta-analysis of Japanese population [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P3-23-07.

Monoclonal antibodies (mAbs) that specifically target podoplanin (PDPN), a marker for type I alveolar cells, are required for immunohistochemical analyses. Anti-PDPN mAbs are available for many species, including human, mouse, rat, rabbit, dog, cat, bovine, pig, Tasmanian devil, alpaca, tiger, whale, goat, horse, bear, sheep, and California sea lion PDPNs. However, no anti-Steller sea lion PDPN (stePDPN) antibody has been developed. Immunohistochemical analysis showed that an anti-California sea lion PDPN mAb (PMab-269) reacted with type I alveolar cells from the Steller sea lion lung, renal glomeruli and Bowman's capsules from kidney, and lymphatic endothelial cells from the colon, indicating that PMab-269 is useful for detecting stePDPN.

CD10 is a glycosylated transmembrane protein and is known as a membrane endopeptidase. CD10 is expressed on predifferentiated lymphocyte progenitor, epithelial, stromal, and tumor cells. Antibodies against CD10 are used for the diagnosis of follicular lymphoma. Anti-human CD10 monoclonal antibody (clone MME/1870) can be used for Western blotting and immunohistochemical analyses. This study examined the critical epitope of MME/1870 using enzyme-linked immunosorbent assay (ELISA) with synthesized peptides. First, we performed ELISA with deletion mutants, and MME/1870 reacted to the 501-520 amino acid sequence of CD10. Next, we analyzed the reaction to 20 point mutants, and MME/1870 did not recognize the alanine-substituted peptides of Y507A, I511A, I512A, and L515A. These results indicate that the binding epitope of MME/1870 includes Tyr507, Ile511, Ile512, and Leu515 of CD10.

The epidermal growth factor receptor (EGFR) is a type I transmembrane protein, which is a member of the human epidermal growth factor receptor (HER) family of receptor tyrosine kinases. EGFR is a c...

Overexpression of human epidermal growth factor receptor 2 (HER2) has been reported in a variety of cancer types, including breast, lung, gastric, pancreatic, and colorectal cancers. Trastuzumab, a...

Human epidermal growth factor receptor 2 (HER2) is a type I transmembrane 185 kDa protein. HER2 is expressed in a variety of normal tissue types and cancer cells. HER2 is associated with cell proli...

CD44 functions as a major hyaluronan receptor on most cell types, with roles in cell adhesion, migration, proliferation, differentiation, and survival. The CD44 gene comprises 20 exons, with alternative splicing producing many different isoforms. CD44 variant isoforms exhibit tissue-specific expression patterns and have been studied as therapeutic targets for several cancers; therefore, anti-CD44 monoclonal antibodies (mAbs) are useful for investigating CD44 expression in various cancers. Previously, we established an anti-CD44 mAb, C44Mab-46 (IgG1, κ), by immunizing mice with the CD44v3-10 ectodomain. Although C44Mab-46 recognized all CD44 isoforms, the binding epitope of C44Mab-46 has not been determined. In this study, we first checked the reactivity of C44Mab-46 to several CD44v3-10 deletion mutants such as dN79, dN124, dN147, and dN224. We found the N-terminus of the C44Mab-46-binding epitope between residues 147 and 224 of CD44v3-10. We next investigated this epitope using a novel mapping system: RIEDL insertion for epitope mapping (REMAP) method. We constructed 31 CD44 standard (CD44s) mutants where the RIEDL tag was inserted into the expected epitope region in CD44s. We observed that the C44Mab-46 epitope constituted five amino acids: 174-TDDDV-178 of CD44s. Thus, the REMAP method could be used to determine mAb binding epitopes for membrane proteins.

The development of protein-specific antibodies is essential for understanding a wide variety of biological phenomena. Parasitic and viral infections and cancers are known to occur within California sea lion (Zalophus californianus) populations. However, sensitive and specific monoclonal antibodies (mAbs) for the pathophysiological analysis of California sea lion tissues have not yet been developed. A type I transmembrane glycoprotein, podoplanin (PDPN), is a known diagnostic marker of lymphatic endothelial cells. We have previously developed several anti-PDPN mAbs in various mammalian species, with applications in flow cytometry, Western blotting, and immunohistochemistry. In this study, we established a novel mAb against California sea lion PDPN (seaPDPN), clone PMab-269 (mouse IgG1, kappa), using a Cell-Based Immunization and Screening method. PMab-269 is specifically detected in seaPDPN-overexpressed Chinese hamster ovary (CHO)-K1 cells using flow cytometry and Western blotting. Moreover, PMab-269 clearly identified pulmonary type I alveolar cells, renal podocytes, and colon lymphatic endothelial cells in California sea lion tissues using immunohistochemistry. These findings demonstrate the usefulness of PMab-269 for the pathophysiological analysis of lung, kidney, and lymphatic tissues of the California sea lion.

CC chemokine receptor 8 (CCR8) belongs to the class A of G protein-coupled receptor. It is highly expressed on Treg and T helper 2 (T

Background Although a docetaxel and cyclophosphomide (TC) regimen without anthracycline as adjuvant therapy became one of the standard regimens especially for ER-positive (ER+)/human epidermal growth factor receptor 2-negative (HER2−) primary breast cancer, the efficacy of TC as neoadjuvant chemotherapy (NAC) is not known. We conducted the prospective trial to assess the efficacy of a TC regimen in the neoadjuvant setting for stage II to III ER+/HER2− primary breast cancer. Patients and Methods A TC regimen that included 75 mg/m2 of docetaxel and 600 mg/m2 of cyclophosphamide for 4 cycles every 3 weeks was administered as NAC. Primary endpoints are the rate of clinical response (clinical partial response and clinical complete response) and pathologic complete response; secondary endpoints are the disease-free survival and overall survival rates. Results Thirty (71.4%) of 42 tumors had clinical response. No patient achieved pathologic complete response. At the median follow-up period of 105.2 months (range, 12.1-119.7 months), the disease-free survival rate was 81.6%, and the distant disease-free survival rate was 86.8%. In terms of survival, only 1 patient died during the study period. The overall survival rate was 97.4% during the study period. Patients who developed distant recurrence had a trend to have progesterone receptor-negative or weakly positive compared with those who did not develop any recurrence (85.7% vs. 45.2%; P = .05). Conclusions Our prospective study showed that a TC regimen as NAC achieved a high clinical response rate in stage II to III ER+/HER2− breast cancer. A TC regimen without anthracycline as NAC might be one of the options for patients with ER+/HER2− breast cancer without high-risk factors including progesterone receptor negativity.

Golden (Syrian) hamster (

The CC chemokine receptor type-4 (CCR4) belongs to the G-protein-coupled receptor superfamily, expressed on the cell surface of T cells and its malignancy. Two CCR4 ligands (CCL17 and CCL22) bind to CCR4 that mediate physiological and pathological functions of T cell immune responses. Anti-CCR4 monoclonal antibody (mAb) mogamulizumab is approved for adult T cell leukemia/lymphoma and cutaneous T cell lymphomas. In addition, mogamulizumab can deplete regulatory T cells, implying the application to solid tumors as an immunomodulator. Therefore, the development of sensitive mAbs for CCR4 has been desired for basic research, diagnosis, and therapy. In this study, a specific, and sensitive anti-mouse CCR4 (mCCR4) mAb, C

A novel coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has caused a global pandemic of coronavirus disease 19. Coronaviruses, including SARS-CoV-2, use RNA-dependent RNA polymerase (RdRP) for viral replication and transcription. Since RdRP is a promising therapeutic target for infection of SARS-CoV-2, it would be beneficial to develop new experimental tools for analysis of the RdRP reaction of SARS-CoV-2. Here, we succeeded to develop novel mouse monoclonal antibodies (mAbs) that recognize SARS-CoV-2 nsp12, catalytic subunit of the RdRP. These anti-nsp12 mAbs, RdMab-2, -13, and -20, specifically recognize SARS-CoV-2 nsp12 by western blotting analysis, while they exhibit less or no cross-reactivity to SARS-CoV nsp12. In addition, SARS-CoV-2 nsp12 was successfully immunoprecipitated using RdMab-2 from lysates of cells overexpressing SARS-CoV-2 nsp12. RdMab-2 was able to detect SARS-CoV-2 nsp12 transiently expressed in established culture cells such as HEK293T cells by indirect immunofluorescence technique. These novel mAbs against SARS-CoV-2 nsp12 are useful to elucidate the RdRP reaction of SARS-CoV-2 and biological cell response against it.

The epidermal growth factor receptor (EGFR) is a transmembrane glycoprotein. Although EGFR is physiologically essential in normal cells, it contributes to tumor malignancy through gene amplification and/or protein overexpression, which augment signaling cascades in tumor cells. We previously developed an anti-human EGFR (hEGFR) monoclonal antibody (mAb), EMab-134 (mouse IgG

The epithelial cell adhesion molecule (EpCAM) is a calcium‑independent, homophilic, intercellular adhesion factor classified as a transmembrane glycoprotein. In addition to cell adhesion, EpCAM also contributes to cell signaling, differentiation, proliferation, and migration. EpCAM is an essential factor in the carcinogenesis of numerous human cancers. In the present study, we developed and validated an anti‑EpCAM monoclonal antibody (mAb), EpMab‑16 (IgG2a, kappa), by immunizing mice with EpCAM‑overexpressing CHO‑K1 cells. EpMab‑16 specifically reacted with endogenous EpCAM in oral squamous cell carcinoma (OSCC) cell lines in flow cytometry and Western blot analyses. It exhibited a plasma membrane‑like stain pattern in OSCC tissues upon immunohistochemical analysis. The KD for EpMab‑16 in SAS and HSC‑2 OSCC cells were assessed via flow cytometry at 1.1x10‑8 and 1.9x10‑8 M, respectively, suggesting moderate binding affinity of EpMab‑16 for EpCAM. We then assessed whether the EpMab‑16 induced antibody‑dependent cellular cytotoxicity (ADCC) and complement‑dependent cytotoxicity (CDC) against OSCC cell lines, and antitumor capacity in a murine xenograft model. In vitro experiments revealed strong ADCC and CDC inducement against OSCC cells treated with EpMab‑16. In vivo experiments on OSCC xenografts revealed that EpMab‑16 treatment significantly reduced tumor growth compared with the control mouse IgG. These data indicated that EpMab‑16 could be a promising treatment option for EpCAM‑expressing OSCCs.

Podoplanin (PDPN), a 36-kDa type I transmembrane O-glycoprotein, is expressed in normal cells, including renal epithelial cells (podocytes), lymphatic endothelial cells, and pulmonary type I alveol...

Overexpression of human epidermal growth factor receptor 2 (HER2) has been reported in glioblastoma as well as breast, gastric, lung, colorectal, and pancreatic cancers. Its expression is associate...

Trastuzumab is a humanized antibody against human epidermal growth factor receptor 2 (HER2) that offers significant survival benefits to patients with HER2-overexpressing breast or gastric cancer. HER2 is also known to be overexpressed in colon cancers. In this study, a novel anti-HER2 monoclonal antibody (mAb), H2Mab-19 (IgG2b, κ) was characterized for its anticancer activity in colon cancers. H2Mab-19 showed both antibody-dependent cellular cytotoxicity and complement-dependent cytotoxicity activities against Caco-2, a colon cancer cell line. Furthermore, H2Mab-19 significantly reduced tumor development in a Caco-2 xenograft model. These results suggest that treatment with H2Mab-19 may be a useful therapy for patients with HER2-expressing colon cancers.

Anti-bear podoplanin (bPDPN) monoclonal antibodies (mAbs), including PMab-247 and PMab-241, have been previously established. Although PMab-247 has shown positive immunostaining for lymphatic endothelial cells (LECs), type I alveolar cells of the lung, and podocytes of the kidney, PMab-241 stains LECs but does not react with lung type I alveolar cells. PDPN possesses three platelet aggregation-stimulating (PLAG) domains (PLAG1, PLAG2, and PLAG3) and the PLAG-like domain (PLD). The binding epitope of PMab-247 was previously determined to include bPDPN residues Asp76, Arg78, Glu80, and Arg82. Among these, Glu80 and Arg82 are included in PLD of bPDPN. The purpose of this study is to determine the binding epitope of PMab-241 and to clarify the difference between these two anti-bPDPN mAbs. Analysis of bPDPN deletion mutants revealed that the N-terminus of the PMab-241 epitope exists between amino acids (aa) 75 and 80 of bPDPN. In addition, analysis of bPDPN point mutants demonstrated that the critical epitope of PMab-241 includes Thr75, Asp76, and Arg78 of bPDPN. The binding epitopes of PMab-241 and PMab-247 seem to overlap, but this slight difference may be sufficient to provide the specificity of PMab-241 to discriminate LECs from type I alveolar cells of the lung.

Overexpression of human epidermal growth factor receptor 2 (HER2) has been reported in breast cancer, gastric, lung, colorectal, oral, and pancreatic cancers. HER2 expression is associated with poo...

Human epidermal growth factor receptor 2 (HER2) is reported to be overexpressed in breast cancers and is associated with poor clinical outcome. Trastuzumab is a humanized anti-HER2 antibody that offers significant survival benefits to patients with HER2-overexpressing breast cancer. In this study, a novel anti-HER2 monoclonal antibody (mAb), H2Mab-19 (IgG2b, kappa) was developed. Antibody-dependent cellular cytotoxicity (ADCC), complement-dependent cytotoxicity (CDC), and antitumor activity of H2Mab-19 were investigated using both breast cancer and oral cancer cell lines. H2Mab-19 demonstrated cytotoxicity in BT-474 (a human breast cancer cell line) and HSC-2 or SAS (human oral cancer cell lines). H2Mab-19 also possessed both ADCC and CDC activity against BT-474, HSC-2, and SAS cell lines. In comparison to control mouse IgG, H2Mab-19 significantly reduced tumor development in BT-474, HSC-2, and SAS xenografts. Collectively, these results suggest that treatment with H2Mab-19 may be a useful therapy for patients with HER2-expressing breast and oral cancers.

Antibody–drug conjugates (ADCs), which consist of a monoclonal antibody (mAb), a linker, and a payload, can deliver a drug to cancer tissues. We previously produced an anti-dog podoplanin (dPDPN) mAb, PMab-38, which reacts with dPDPN-expressing canine melanomas and squamous cell carcinomas (SCCs), but not with dPDPN-expressing canine type I alveolar cells or lymphatic endothelial cells, indicating that PMab-38 possesses cancer specificity. In this study, we developed an ADC, P38B-DM1, using the mouse–canine chimeric anti-dPDPN antibody, P38B as the antibody, a peptide linker, and emtansine as the payload using the chemical conjugation by affinity peptide (CCAP) method. We investigated its cytotoxicity against dPDPN-overexpressed Chinese hamster ovary (CHO/dPDPN) cells in vitro and its antitumor activity using a mouse xenograft model of CHO/dPDPN cells. P38B-DM1 showed cytotoxicity to CHO/dPDPN cells in a dose-dependent manner in vitro. Furthermore, P38B-DM1 exhibited higher antitumor activity than P38B in the mouse xenograft model. These results suggest that P38B-DM1, developed using the CCAP method, is useful for antibody therapy against dPDPN-expressing canine SCCs and melanomas.

CD19 is a type I transmembrane glycoprotein belonging to the immunoglobulin superfamily. It is expressed in normal and neoplastic B cells, and it modulates the threshold of B cell activation for amplifying B cell receptor signaling. Blinatumomab (a CD3-CD19-bispecific T cell-engaging antibody) and tisagenlecleucel (genetically modified T cells that express a CD19 chimeric antigen receptor [CART-19]) provide significant benefits for patients with CD19-positive relapsed or refractory B cell malignancies. In this study, we first employed the Cell-Based Immunization and Screening (CBIS) method to produce anti-CD19 monoclonal antibodies using CD19-overexpressing cells for both immunization and screening. One established clone-C19Mab-1-proved to be useful in flow cytometry assays against lymphoma cell lines, such as BALL-1, P30/OHK, and Raji. Second, the extracellular domain of CD19 was immunized into mice, and enzyme-linked immunosorbent assays were performed for the first screening. One established clone-C19Mab-3-was determined to be useful for Western blotting and immunohistochemical analysis. Due to their complementary utility, a combination of C19Mab-1 (established using CBIS) and C19Mab-3 (established using conventional method) could be useful for the pathological analysis of CD19.

Recent evidence indicates that RNA-dependent RNA polymerase (RdRP) activity of human telomerase reverse transcriptase (hTERT) regulates expression of target genes and is directly involved in tumor formation in a telomere-independent manner. Non-canonical function of hTERT has been considered as a therapeutic target for cancer therapy. We have previously shown that hTERT phosphorylation at threonine 249 (p-hTERT), which promotes RdRP activity, is an indicator of an aggressive phenotype and poor prognosis in liver and pancreatic cancers, using two cohorts with small sample sizes with polyclonal p-hTERT antibody. To clarify the clinical relevance of p-hTERT, we developed a specific monoclonal antibody and determined the diagnostic and prognostic value of p-hTERT in cancer specimens using a large cohort. A monoclonal antibody for phosphorylated hTERT (p-hTERT) at threonine 249 was developed and validated. The antibody was used for the immunohistochemical staining of formalin-fixed, paraffin-embedded specimens from 1523 cases of lung, colon, stomach, pancreatic, liver, breast, and kidney cancers. We detected elevated p-hTERT expression levels in cases with a high mitotic activity, high pathological grade, and high nuclear pleomorphism. Elevated p-hTERT expression was an independent prognostic factor for lung, pancreatic, and liver cancers. Furthermore, p-hTERT expression was associated with immature and aggressive features, such as adenosquamous carcinoma (lung and pancreas), invasive type of cancer (lung), high serum alpha-fetoprotein level (liver), and triple-negative status (breast). In conclusion, RdRP activity indicated by p-hTERT expression predicts aggressive cancer phenotypes in various types of cancer. Thus, p-hTERT is a novel biomarker for the diagnosis of aggressive cancers with a poor prognosis. © 2022 The Authors. The Journal of Pathology published by John WileySons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

One of G protein-coupled receptors, CCR9, is mainly expressed in the thymocytes and the small bowel. The ligand of CCR9 is CCL25 (TECK), and the CCR9-CCL25 axis controls T cell maturation and intestinal immune response. CCR9 is related to graft-versus-host disease and autoimmune diseases. Recent studies have been reported that CCR9 is also associated with tumor proliferation, apoptosis, migration, and drug resistance. Therefore, CCR9-targeting therapy is receiving a lot of attention. Previously, we developed an anti-human CCR9 (hCCR9) monoclonal antibody, C

Human epidermal growth factor receptor 2 (HER2) is a type I transmembrane 185 kDa protein expressed in various types of normal or cancer cells. Overexpression of HER2 is found in many cancers and is related to cell proliferation, differentiation, and migration. We recently developed a novel anti-HER2 monoclonal antibody, H

CD20 is a glycosylated transmembrane protein and is expressed on normal B cells and B cell malignancies. Therapeutic antibodies against CD20 are developed and used in clinic. The understanding of antibody-antigen binding by revealing the epitope is essential for future application to antibody technology. Previously, we developed an anti-human CD20 monoclonal antibody, C

The epidermal growth factor receptor (EGFR) is a type I transmembrane protein, which is a member of the human epidermal growth factor receptor (HER) family of receptor tyrosine kinases. EGFR is a crucial mediator of cell growth and differentiation and forms homodimers or heterodimers with other HER family members to activate downstream signaling cascades. We previously established an anti-human EGFR (hEGFR) monoclonal antibody (mAb), clone EMab-134 (mouse IgG

Overexpression of human epidermal growth factor receptor 2 (HER2) has been reported in a variety of cancer types, including breast, lung, gastric, pancreatic, and colorectal cancers. Trastuzumab, a humanized anti-HER2 monoclonal antibody (mAb), has been shown to provide significant survival benefits in HER2-overexpressing breast cancer and gastric cancer patients. Previously, an anti-HER2 mAb, H

Human epidermal growth factor receptor 2 (HER2) is a type I transmembrane 185 kDa protein. HER2 is expressed in a variety of normal tissue types and cancer cells. HER2 is associated with cell proliferation, differentiation, and migration. The overexpression of HER2 has been observed in a number of cancers, including breast and gastric cancers. Gastric cancer is one of the most common cancers worldwide, with an annual case rate of ∼1 million people diagnosed with the disease. Trastuzumab is a humanized anti-HER2 monoclonal antibody (mAb) that has been utilized in gastric cancer therapy. In this study, we have developed a novel anti-HER2 mAb, H

Podoplanin (PDPN) plays a pivotal role in platelet aggregation, embryo development, and tumor progression. PDPN is universally expressed in many mammalian species, and is considered a typical lymphatic endothelial cell marker. We have previously developed the mouse anti-California sea lion (

CD44 is a type I transmembrane protein expressed in various kinds of normal cancer cells, including pancreatic, breast, and oral cancers. CD44 is associated with cancer progression, metastases, and treatment resistance. CD44 consists of 20 exons, and various isoforms exist due to alternative splicing of the central 10 exons. Some splicing variants show cancer-specific expression patterns and are related to prognosis of patients with cancer. Therefore, CD44 targeting therapy has been attracting attention. In a previous study, we established an anti-CD44 monoclonal antibody, C