Induction of specific immunosuppression of cardiac allograft rejection withmonoclonal antibodies to CD44, LFA-1 and ICAM-1

Objective:To evaluate the immunosuppressive effect of monoclonal antibodies (McAb) against cell surface adhesion molecules on transplant rejection. Methods: C57BL/6 (H-2b) mouse cardiac grafts were transplanted into BALB/c(H- 2d) mice. This model was used to investigate the possibility of immunosuppressive induction with CD44 McAb, leukocyte function associated antigen (LFA-1) and intercellular adhesion molecule (ICAM-1). Results: Treatment of the allograft recipients with CD44 McAb alone, or both LFA-1 and ICAM-1 or combination of these 3 McAb significantly prolonged the cardiac allografts survival as compared with PBS controls (P<0.01). The combination of anti-CD44 and ICAM-1 and LFA-1 McAb was shown to produce more significant prolongation of grafts survival than anti-CD44 McAb alone or both anti-ICAM- 1 and LFA-1 McAb (P < 0.01). Histological examination of the grafts treated with the McAb displayed greatly reduced mononuclear cell infiltration. The proliferation of spleen cells from recipient BALB/c with McAb treatment was significantly inhibited in response to the stimulators of C57BL/6 spleen cells, but increased upon the stimulation of C3H/He (H-2k) spleen cells, as demonstrated by mixed lymphocyte reaction. Similarly, the cytotoxic activity against donor H-2-compatible (H-2b) target cells, EL-4 cells, was significantly suppressed. The spleen cells from allografted recipient BALB/c mice with McAb treatment induced specific tolerance for C57BL/6 cardiac grafts in allografted recipients, whereas those from allografted BALB/c mice without McAb treatment induced acute rejection. Conclusion: These results indicate that antiadhesion therapy using a combination of McAb to adhesion molecules can induce specific immunosuppression of transplant rejection.

Expression of Anti-CD4 Human/Murine Chimeric Antibody and Their Killer Tumor Activity

From the mouse hybridoma cell line secreting an anti-CD4 monoclonal antibody (McAb), total RNA was prepared. The VH and VL genes were amplified by RT-PCR with family specific primer pairs. The PCR products were cloned into pGEM-T vectors, then tranfected into JM109. The VH and VL genes were snalyzed by automatic DNA sequencer. According to Kabat classification, the VH and VL genes belong to the mouse ig heavy subgroup Ⅱ(A) and x chain subgroupⅢ, respectively. The VH and VL genes were subcloned into pr1-Expr and Pk Expr respectively, then transfected into XL2-Blue. The VH- Pr1 and VL- pk were trans feeted by electroporation into mouse myeloma cell X63Ag8. 653. The transfectoma cells were selected by G418 screening, and then supernatant of cultured transfectoma were analyzed by ELISA and immunofluorescence techniques.We have acquired transfectoma cells secreting anti-CD4 chimeric antibodies.These chimeric antibodies are able to kill tumor cells specifically in vitro.

重组人14-3-3zeta亚型单克隆抗体的制备、鉴定及初步应用

目的制备重组人14-3-3zeta亚型单克隆抗体(McAb),并检测14-3-3蛋白在人体组织器官的分布。方法将筛选出分泌抗人14-3-3zeta的杂交瘤细胞注射入BALB/c小鼠腹腔,制备腹水McAb,用辛酸-饱和硫酸铵沉淀法纯化,并鉴定其效价、纯度、浓度、特异性以及与天然抗原的亲和力,再用此单抗检测14-3-3蛋白在人体组织器官的分布。结果腹水及纯化后的单克隆抗体的效价分别为1∶107和1∶106。纯化后的纯度达97%,浓度为5mg/ml,能识别天然的人14-3-3蛋白,并能有效地识别兔和鼠脑组织的14-3-3蛋白。在人脑、肾、肺、肝、胃、卵巢、乳腺、结肠、胰腺等组织器官中,均检出14-3-3蛋白。结论已成功制备出重组人14-3-3zeta亚型单克隆抗体,并应用于实际检测,为研究14-3-3蛋白在机体生理和病理情况下的作用机制奠定了基础。

抗角蛋白14单克隆抗体对无血清培养角质形成细胞增殖的影响

目的:建立一种无血清传代培养人角质形成细胞(KC)的方法,并观察角蛋白14单克隆抗体(anti-K14 mAb)对无血清培养人角质形成细胞体外增殖的影响。方法:应用角质形成细胞无血清培养基(KC-SFM)添加重组表皮生长因子(EGF)和牛垂体浸出液(BPE)传代培养角质形成细胞,培养均至第3代时于培养基中加人不同浓度的anti-K14 mAb,用MTT法观察对角质形成细胞增殖的影响。结果:应用无血清培养基成功地传代培养了角质形成细胞,MTT法结果显示各浓度组对培养的角质形成细胞的增殖有显著抑制作用并有浓度依赖性。结论:建立了一种无血清培养人角质形成细胞的方法a,nti-K14mAb对人角质形成细胞体外的增殖有显著抑制作用。

Evaluation of teplizumab's efficacy and safety in treatment of type 1 diabetes mellitus:A systematic review and meta-analysis

BACKGROUND Islets of Langerhans beta cells diminish in autoimmune type 1 diabetes mellitus(T1DM).Teplizumab,a humanized anti-CD3 monoclonal antibody,may help T1DM.Its long-term implications on clinical T1DM development,safety,and efficacy are unknown.AIM To assess the effectiveness and safety of teplizumab as a therapeutic intervention for individuals with T1DM.METHODS A systematic search was conducted using four electronic databases(PubMed,Embase,Scopus,and Cochrane Library)to select publications published in peerreviewed journals written in English.The odds ratio(OR)and risk ratio(RR)were calculated,along with their 95%CI.We assessed heterogeneity using Cochrane Q and I2 statistics and the appropriate P value.RESULTS There were 8 randomized controlled trials(RCTs)in the current meta-analysis with a total of 1908 T1DM patients from diverse age cohorts,with 1361 patients receiving Teplizumab and 547 patients receiving a placebo.Teplizumab was found to have a substantial link with a decrease in insulin consumption,with an OR of 4.13(95%CI:1.72 to 9.90).Teplizumab is associated with an improved Cpeptide response(OR 2.49;95%CI:1.62 to 3.81)and a significant change in Glycated haemoglobin A1c(HbA1c)levels in people with type 1 diabetes[OR 1.75(95%CI:1.03 to 2.98)],and it has a RR of 0.71(95%CI:0.53 to 0.95).CONCLUSION In type 1 diabetics,teplizumab decreased insulin consumption,improved C-peptide response,and significantly changed HbA1c levels with negligible side effects.Teplizumab appears to improve glycaemic control and diabetes management with good safety and efficacy.

14-3-3ζ蛋白单克隆抗体的制备、鉴定及初步应用

为了探讨14-3-3ζ蛋白在中枢神经系统内的分布,本文采用纯化的基因重组型14-3-3ζ蛋白免疫Balb/c小鼠,用杂交瘤技术制备抗14-3-3ζ蛋白单克隆抗体;Western blot及免疫组织化学法鉴定抗体。结果显示:制备的单克隆抗体能特异性识别基因重组14-3-3ζ蛋白和大鼠脑匀浆32kD蛋白。免疫组化染色结果显示,14-3-3ζ蛋白在大鼠中枢神经系统广泛分布,在皮层、海马、杏仁核和基底前脑的免疫阳性染色较强,免疫阳性产物位于神经元胞浆内。本研究结果提示,14-3-3ζ蛋白可能具有多样化的生理功能。

重组小鼠脑14-3-3γ蛋白单克隆抗体的制备及鉴定

目的制备重组小鼠脑14-3-3γ蛋白单克隆抗体(McAb),为神经系统退行性疾病的诊断提供标志物。方法采用重组小鼠脑14-3-3γ蛋白免疫小鼠,制备抗小鼠脑14-3-3γ蛋白的多克隆抗体,并应用多克隆血清检测14-3-3蛋白在大鼠脑中的分布。进一步应用杂交瘤技术制备其单克隆抗体,并鉴定其特异性以及与天然抗原的亲合力。结果制备的多克隆血清能有效识别大鼠脑组织的14-3-3蛋白,免疫组化显示在黑质,蓝斑,室周核,背外侧核染色阳性。制备的单克隆抗体可特异性识别重组14-3-3γ蛋白、大鼠脑及人脑中14-3-3蛋白。结论重组小鼠脑14-3-3γ蛋白多克隆血清和单克隆抗体成功制备;此可用于神经系统退行性疾病的诊断。

Treatment strategies for nodal and gastrointestinal follicular lymphoma:Current status and future development

In recent years,therapies for follicular lymphoma (FL) have steadily improved.A series of phase Ⅲ trials comparing the effect of rituximab with chemotherapy vs chemotherapy alone in treating FL have indicated significant improvements in progression-free survival (PFS) and overall survival.Recent studies have found that prolonged response durations and PFS were obtained with maintenance therapy using rituximab or interferon after completion of first line therapy.For patients with relapsed or refractory FL,phase Ⅱ studies have assessed the effectiveness of combination therapies using a Toll-like receptor-9 agonist (1018ISS),oblimersen sodium (a Bcl-2 antisense oligonucleotide),bendamustine,and rituximab,as well as veltuzumab,a new humanized anti-CD20 antibody,and epratuzumab.In addition,the effectiveness of yttrium-90 ibritumomab tiuxetan and iodine-131 tositumomab as radioimmunotherapies has been reported.Furthermore,three phase Ⅲ studies on an idiotype vaccine are near completion.Unfortunately,these vaccines,which appeared highly effective in phase Ⅰ and Ⅱ trials,do not appear to result in prolonged PFS.This report will summarize the current knowledge on therapies for treatment of FL,and will conclude with a brief discussion of feasiblefuture options for effective treatments.Lastly,we added descriptions of the management of gastrointestinal FL,which is considered to be controversial because it is rare.

A multi-center,open-label,randomized,parallel-controlled phase II study comparing pharmacokinetic,pharmacodynamics and safety of ripertamab(SCT400)to rituximab(Mab Thera?)in patients with CD20-positive B-cell non-Hodgkin lymphoma

Objective:This multi-center,open-label,randomized,parallel-controlled phaseⅡstudy aimed to compare the pharmacokinetics(PK),pharmacodynamics(PD)and safety profile of ripertamab(SCT400),a recombinant antiCD20 monoclonal antibody,to rituximab(MabThera^(■))in patients with CD20-positive B-cell non-Hodgkin lymphoma(NHL).Methods:Patients with CD20-positive B-cell NHL who achieved complete remission or unconfirmed complete remission after standard treatment were randomly assigned at a 1:1 ratio to receive a single dose of ripertamab(375mg/m^(2))or rituximab(MabThera^(■),375 mg/m^(2)).PK was evaluated using area under the concentration-time curve(AUC)from time 0 to d 85(AUC_(0-85d)),AUC from time 0 to week 1(AUC0-1 w),AUC from time 0 to week 2(AUC_(0-2 w)),AUC from time 0 to week 3(AUC_(0-3 w)),AUC from time 0 to week 8(AUC_(0-8 w)),maximum serum concentration(C_(max)),terminal half-life(T_(1/2)),time to maximum serum concentration(T_(max))and clearance(CL).Bioequivalence was confirmed if the 90%confidence interval(90%CI)of the geometric mean ratio of ripertamab/rituximab was within the pre-defined bioequivalence range of 80.0%-125.0%.PD,immunogenicity,and safety were also evaluated.Results:From December 30,2014 to November 24,2015,a total of 84 patients were randomized(ripertamab,n=42;rituximab,n=42)and the PK analysis was performed on 76 patients(ripertamab,n=38;rituximab,n=38).The geometric mean ratios of ripertamab/rituximab for AUC_(0-85d),ATC_(0-inf),and Cmaxwere 96.1%(90%CI:87.6%-105.5%),95.9%(90%CI:86.5%-106.4%)and 97.4%(90%CI:91.6%-103.6%),respectively.All PK parameters met the pre-defined bioequivalence range of 80.0%-125.0%.For PD and safety evaluation,there was no statistical difference in peripheral CD 19-positive B-cell counts and CD20-positive B-cell counts at each visit,and no difference in the incidence of anti-drug antibodies was observed between the two groups.The incidences of treatment-emergent adverse events and treatment-related adverse events were also comparable between the two groups.Conclusions:In this study,the PK,PD,immunogenicity,and safety profile of ripertamab(SCT400)were similar to rituximab(MabThera^(■))in Chinese patients with CD20-positive B-cell NHL.

鸭RIG-Ⅰ蛋白C端helicase结构域和RD结构域的原核表达及其单克隆抗体的制备

利用PCR技术将鸭维甲酸诱导基因Ⅰ(RIG-Ⅰ)helicase区和RD区部分编码序列分别进行扩增,并分别命名为c、d段;克隆到p ET30a原核表达载体,构建了重组原核表达质粒p ET30a-c和p ET30a-d,通过转化BL21(DE3)感受态菌、IPTG诱导、镍柱纯化表达蛋白,将纯化的c、d蛋白免疫小鼠制备单克隆抗体(m Ab),采用ELISA、Western blot和间接免疫荧光试验对单克隆抗体进行鉴定分析。获得鼠抗鸭RIG-Ⅰ单克隆抗体有14株与原核分段表达的c、d蛋白有良好的反应性,其中3株与真核表达的RIG-Ⅰ蛋白有良好的反应性。制备的鼠抗鸭RIG-Ⅰ单克隆抗体为RIG-Ⅰ在抗病毒天然免疫信号转导途径的研究奠定了基础。

Biodistribution and Anti-tumor Activities of the ^(131)I-labeled Rituximab in Nude Mice Bearing Human Burkitt's lymphoma

OBJECTIVE To explore the biodistribution and anti-tumoractivity of ^(131)I labeled rituximab injected intratumorally orintraperitoneally in vivo in nude mice bearing Raji human Burkitt's lymphoma xenografts.METHODS The rituximab and the mouse IgG were labeled withNa^(131)I using the IODO-GEN method.BALB/C nude mice werexenografted with ^(131)I-Rituximab or ^(131)I-IgG and killed on the 1st,3rd,7th,and 15th day after injection.The tumor/non-tumor ratio(T/NT)and the dose injected in each gram of the tissue(%ID/g)from12 organs or tissues of interest,e.g.tumor,blood,were calculated.The long and short axes of each tumor were measured by calipersat 2-3-day intervals after treatment,and the growth inhibition ofthe tumor was calculated using the MIRD formula.RESULTS When comparing intraperitoneal injection(IP)andintratumoral injection(IT)of ^(131)I-IgG,intratumoral injection of^(131)I-rituximab produced a significantly higher tumor/non-tumorratio in all tissues and organs of interest on the 1st,3rd,and 7thday,respectively(P<0.05).The %ID/g of tumor was 1.4-1.7-foldand 1.5-3.7-fold in the IP and IgG IT groups,respectively,but the%ID/g of non-tumors was significantly lower in the IP group andIgG IT group.Similarly,the tumor growth was greatly inhibitedby intratumoral injection of the ^(131)I-rituximab,whereas it wasless inhibited by other forms of the treatment(P<0.05).However^(131)I-rituximab injected intratumorally inhibited tumor growth ina dose-dependent manner.The inhibition rate was less with alow dose(75μCi)and greater with a high dose(150μCi),yet thedifference was not significant(P>0.05).CONCLUSION Tumors can absorb the highest amount of theradiolabelled antibodies,and the tumor/non-tumor ratios in thegroup with intratumoral injection of the ^(131)I-rituximab resulted inthe optimal anti-tumor activity.

MMP14单克隆抗体对口腔鳞状细胞癌增殖、凋亡的影响

[目的]探究MMP14单克隆抗体对口腔鳞状细胞癌细胞增殖、凋亡的影响。[方法]构建MMP14敲低(Kd-TCa8113)、过表达(Kd-TCa8113)细胞株,与野生型TCa8113(Wt-TCa8113)对比,考察MMP14对TCa8113细胞增殖、凋亡的影响。用不同浓度的MMP14单克隆抗体与TCa8113共培养,以探讨MMP14单克隆抗体对TCa8113细胞增殖、凋亡的影响。[结果]以Wt-TCa8113为对照组,Kd-TCa8113组、Kd-TCa8113组的细胞培养48 h的增殖率分别为74.55%、114.79%,P均<0.05。流式细胞术结果显示,Wt-TCa8113、Kd-TCa8113和Oe-TCa8113培养48 h后的细胞凋亡率分别为3.47%±0.36%、33.68%±7.33%和1.60%±0.22%,P均<0.05。用50μg/mL、100μg/mL和200μg/mL浓度的抗体处理TCa8113细胞24 h后,以PBS处理组为对照,细胞增殖率分别为93.52%、90.75%和87.61%,P均<0.05。流式细胞术结果显示,PBS组和上述抗体处理组的细胞凋亡率分别为3.47%±0.36%、11.72%±2.03%、15.52%±3.05%和21.59%±4.49%,抗体处理组的细胞凋亡率均较PBS组高,P均<0.05。[结论]MMP14表达能显著促进TCa8113细胞的增殖和抗凋亡能力。MMP14单克隆抗体能显著抑制TCa8113细胞的增殖和抗凋亡能力。

抗日本血吸虫重组信号蛋白14-3-3单克隆抗体的制备和鉴定

目的制备抗日本血吸虫重组信号蛋白14-3-3单克隆抗体,并鉴定抗体性质。方法以重组表达纯化的日本血吸虫信号蛋白14-3-3为抗原免疫BALB/c小鼠,采用杂交瘤技术制备单克隆抗体,采用酶联免疫吸附试验及免疫印迹法对获得的单克隆抗体进行类和亚类、效价、浓度、纯度、亲和常数、特异性和检测灵敏度的测定与鉴定。结果共获得6株针对日本血吸虫信号蛋白14-3-3的单克隆抗体,分别为5G9、3F1、3F7、5C6、5D1和1G6,抗体类型分别为IgG1、IgG1、IgG2a、IgG2b、IgG1和IgG1。对其中的单克隆抗体5G9分析显示,制备的腹水抗体效价为1∶1.28×105,亲和层析纯化后的浓度为5.3 mg/ml,纯度>95%,亲和常数为5.1×107mol/L。免疫印迹试验结果表明,该单克隆抗体可与体外重组表达纯化的日本血吸虫14-3-3蛋白特异性结合,同时也能与日本血吸虫可溶性虫卵抗原、成虫排泄分泌抗原和成虫抗原特异性反应,而与大肠埃希菌、健康人血清和华支睾吸虫抗原均无明显交叉反应。HRP标记的单克隆抗体5G9检测14-3-3蛋白的灵敏度为31.25 ng/ml。结论本研究获得了6株能稳定分泌抗日本血吸虫14-3-3蛋白的单克隆抗体杂交瘤细胞株,为建立新的日本血吸虫活动性感染检测方法奠定了良好的基础。

抗日本血吸虫14-3-3蛋白单克隆抗体5C6抗原识别表位的鉴定

目的采用噬菌体展示肽技术鉴定抗日本血吸虫14-3-3蛋白单克隆抗体5C6的抗原识别表位。方法将纯化的抗日本血吸虫14-3-3蛋白单克隆抗体5C6作为固相配基筛选噬菌体随机展示12肽库,按照吸附-洗脱-扩增的淘洗过程进行3轮生物淘洗,富集特异性结合的噬菌体颗粒。随机挑取第3轮洗脱的独立噬菌体克隆,分别依次进行噬菌体扩增、基因组DNA抽提和DNA序列分析。选择外源性插入DNA序列完全相同或高度相似的同源性噬菌体,采用ELISA及免疫印迹分析对其免疫反应性作进一步鉴定,以确定单克隆抗体5C6的抗原识别表位。结果第3轮淘洗物中33个独立噬菌体克隆的DNA测序结果显示,其中25个噬菌体编码外源性插入肽的核酸序列均为5′-CCACCTAGTAGCAGACCGATTCT-CAGTCGAAGGAAA-3′,其对应的演绎氨基酸序列为PPSSRPILSRRK,该肽与日本血吸虫信号蛋白14-3-3及自然界其他已知蛋白的氨基酸序列均无同源性。免疫印迹试验证实此短肽可被自然感染的日本血吸虫病人血清所识别,而不与健康人血清反应。结论本研究成功鉴定了抗日本血吸虫14-3-3蛋白单克隆抗体5C6所识别的模拟抗原表位,并证明该表位为空间构像表位。

Advances in the treatment of IgA nephropathy with biological agents

Immunoglobulin A nephropathy(IgAN)is the most common primary glomerular disease,and the“four-hit”theory represents its currently accepted pathogenic mechanism.Mucosal immunity triggered by infections in the respiratory tract,intestines,or other areas leads to antigen presentation,T cell stimulation,B cell maturation,and the production of IgA-producing plasma cells.The proteins B-lymphocyte stimulator(BLyS)and a proliferation-inducing ligand(APRIL)are involved in this process,and alternative complement and lectin pathway activation are also part of the pathogenic mechanism.Kidney Disease Improving Global Outcomes guidelines indicate that a specific effective treatment for IgAN is lacking,with renin-angiotensin-aldosterone system inhibitors being the primary therapy.Recent research shows that biological agents can significantly reduce proteinuria,stabilize the estimated glomerular filtration rate,and reverse some pathological changes,such as endocapillary proliferation and crescent formation.There are four main categories of biological agents used to treat IgA nephropathy,specifically anti-CD20 monoclonal antibodies,anti-BLyS or APRIL monoclonal antibodies,monoclonal antibodies targeting both BLyS and APRIL(telitacicept and atacicept),and monoclonal antibodies inhibiting complement system activation(narsoplimab and eculizumab).However,further research on the dosages,treatment duration,long-term efficacy,and safety of these biological agents is required.

14型肺炎球菌多糖单克隆抗体的制备与初步应用

目的制备14型肺炎球菌多糖单克隆抗体,并进行鉴定及初步应用。方法制备免疫原,免疫BALB/c小鼠,制备单克隆抗体,经3次亚克隆筛选单抗细胞株,并制备腹水。对筛选的单抗进行ELISA效价、特异性、亚型、中和效价、浊度法特异性等鉴定。采用制备的单抗腹水检测市售23价肺炎球菌多糖疫苗、7价肺炎球菌结合疫苗中14型肺炎球菌多糖含量,计算回收率;并与丹麦血清研究所（State Serum Institute,SSI）14型肺炎球菌多糖兔多抗血清检测结果进行比较,计算两者之间的变异系数（CV）。结果共获得7株14型肺炎球菌多糖单抗细胞株：PP-14-101~107,效价分别为105、104、104、104、105、105、105;7株单抗与23价肺炎疫苗中包含的除14型以外的其他所有血清型的多糖均不发生交叉反应;PP-14-101、104、105、106这4株单抗具有免疫浊度趋势,另3株单抗无浊度信号;PP-14-101和PP-14-104株单抗与6A、33F型肺炎球菌多糖具有一定的交叉反应,而PP-14-105和PP-14-106株单抗与23型多糖均无交叉反应;PP-14-101、PP-14-104株单抗为Ig M亚型,PP-14-105、PP-14-106株单抗为Ig G1亚型,PP-14-106比PP-14-105株单抗稀释倍数高,反应性更强,因此选择PP-14-106株单抗为目标单抗;PP-14-106株单抗腹水对14型肺炎球菌的中和效价远高于1∶17 496,中和效价较高;采用PP-14-106株单抗腹水检测市售23价肺炎球菌多糖疫苗和7价肺炎球菌结合疫苗,回收率为90.2%~120.0%,该单抗与SSI血清检测上述疫苗成品14型肺炎球菌多糖含量的CV值在2.5%~11.9%之间。结论成功获得1株效价高、具有杀菌活性、特异性好的单抗,该单抗具有免疫浊度趋势,能准确测定肺炎球菌疫苗中的多糖含量,可替代SSI血清用于多糖疫苗和结合疫苗中14型肺炎球菌多糖含量的定量检测。

Clinical significance of the loss of CD20 antigen on tumor cells in patients with relapsed or refractory follicular lymphoma

Aim:Anti-CD20 monoclonal antibody is a cornerstone therapy for follicular lymphoma.Following anti-CD20 therapy,a potential decrease in CD20 antigen,and therefore a loss of the tumor target might be expected.However,the incidence and clinical significance of CD20 loss on tumor cells in patients with relapsed or refractory follicular lymphoma are unknown.This study aims to investigate the incidence and outcome of patients with relapsed or refractory follicular lymphoma patients harboring the loss of the tumor target,CD20.Methods:All consecutive adult patients with relapsed or refractory follicular lymphoma referred to the Early Drug Department at Gustave Roussy were included.The main objectives were to assess the incidence and prognosis of the loss in expression of CD20 antigen on the surface of tumor cells on patient outcome.Results:Over the study period 2013-2018,131 patients were screened for clinical trials with B-cell malignancies in the early drug department of Gustave Roussy in France.Forty-four patients presented with relapsed or refractory follicular lymphoma and 32 had tumor biopsies at the time of relapse that were retained for analysis.The median(range)age was 67.5 years(55.3-75.3)and the median number of prior anti-cancer systemic therapies was 3(2-4).At the time of relapse,CD20 expression was positive in 84%of tumors(n=27)and negative in 16%of tumors(n=5).At a median follow-up of 18.3(0.6-83.3)months,CD20 negativity was associated with a poorer prognosis with a median overall survival of 8.9 months(95%CI:2.4-19.1)in comparison to CD20 positive patients(28.3 months,95%CI:25.1-75.3 months,P=0.019).Conclusion:The loss of the tumor target antigen,CD20,occurred in 16%of patients with relapse or refractory follicular lymphoma.Due to confounding factors in patients who received anti-CD20 immunotherapy,it was not possible to formally establish the prognostic significance of CD20 negativity.However,we suggest that a check for CD20 antigen positivity nevertheless be performed to adapt subsequent therapies for patients with relapsed or refractory follicular lymphoma.