Characterization of parotid gland tumors using diffusion-relaxation correlation spectrum imaging: a preliminary study

AIM

To assess the performance of diffusion-relaxation correlation spectrum imaging (DR-CSI) in the characterization of parotid gland tumors.

MATERIALS AND METHODS

Twenty-five pleomorphic adenomas (PA) patients, 9 Warthin's tumors (WT) patients and 7 malignant tumors (MT) patients were prospectively recruited. DR-CSI (7 b-values combined with 5 TEs, totally 35 diffusion-weighted images) was scanned for pre-treatment assessment. Diffusion (D)-T2 signal spectrum summating all voxels were built for each patient, characterized by D-axis with range 0∼5 × 10-3 mm2/s, and T2-axis with range 0∼300ms. With boundaries of 0.5 and 2.5 × 10-3 mm2/s for D, all spectra were divided into three compartments labeled A (low D), B (mediate D) and C (high D). Volume fractions acquired from each compartment (VA, VB, VC) were compared among PA, WT and MT. Diagnostic performance was assessed using receiver operating characteristic analysis and area under the curve (AUC).

RESULTS

Each subtype of parotid tumors had their specific D-T2 spectrum. PA showed significantly lower VA (8.85 ± 4.77% vs 20.68 ± 10.85%), higher VB (63.40 ± 8.18% vs 43.05 ± 7.16%), and lower VC (27.75 ± 8.51% vs 36.27 ± 11.09) than WT (all p<0.05). VB showed optimal diagnostic performance (AUC 0.969, sensitivity 92.00%, specificity 100.00%). MT showed significantly higher VA (21.23 ± 12.36%), lower VB (37.09 ± 6.43%), and higher VC (41.68 ± 13.72%) than PA (all p<0.05). Similarly, VB showed optimal diagnostic performance (AUC 0.994, sensitivity 96.00%, specificity 100.00%). No significant difference of VA, VB and VC was found between WT and MT.

CONCLUSIONS

DR-CSI might be a promising and non-invasive way for characterizing parotid gland tumors.

A phase 1, open-label, dose escalation and expansion, multicenter study of claudin 18.2-targeted chimeric antigen receptor T-cells in patients with unresectable, locally advanced, or metastatic gastric, gastroesophageal junction, esophageal, or pancreatic adenocarcinoma

TPS480

Background: Locally advanced and metastatic gastric, esophageal, gastroesophageal junction, and pancreatic adenocarcinomas (GC, EC, GEJC, and PC) have poor overall survival, and more effective therapies are needed. Claudin 18.2 (CLDN18.2), a tight junction protein, is commonly expressed in these cancers. Monoclonal antibody and CAR-T cell therapies targeting CLDN18.2 have shown promising antitumor activity (Türeci O et al, 2019; Qi C et al, 2022). This study aims to assess the safety and preliminary efficacy of a CLDN18.2 targeted CAR-T, LB1908, in subjects with GC, EC, GEJC, and PC. Methods: This is a phase 1, open-label, multicenter, dose-escalation and expansion study of LB1908 that aims to identify the recommended phase 2 dose (NCT05539430; open to enrollment early 2023). During prescreening, that may occur as early as at initial diagnosis, we will screen subjects for tumor expression of CLDN18.2 by IHC of ≥ 1+ in ≥ 50% of tumor cells. Inclusion criteria include: must be ≥18 and ≤75 years old; histologically/cytologically confirmed unresectable, locally advanced, or metastatic adenocarcinoma of the GC, EC, GEJC, and PC; progressed on at least standard 1st line therapy; ECOG PS 0 or 1; life expectancy > 4 months per investigator judgment; and adequate organ function per protocol. The study has 2 parts. In Part A (dose escalation), 12 to 21 subjects with GC, EC, or GEJC will be enrolled in up to 3 planned dose level cohorts (0.5X106, 1.5X106, and 3.0X106 CAR+ viable T cells/kg), to determine the recommended dose for expansion (RDE). In Part B (dose expansion) the RDE will be administered to up to 35 subjects with GC, EC, and GEJC in one expansion cohort and PC in another cohort (n=11-17 for GC/EC/GEJ, to total 23 subjects when pooling with RDE-treated subjects from part A; n=18 for PC). LB1908 will be manufactured from autologous T cells collected via PMBC apheresis. Subjects may receive optional bridging therapy followed by lymphodepleting chemotherapy with fludarabine 30 mg/m2/day and cyclophosphamide 300 mg/m2/day for 3 days. One infusion of LB1908 will then be administered, and subjects will be followed post-infusion for safety, laboratory, and disease assessments. Primary endpoints are incidence, duration, and severity of AEs and laboratory abnormalities (Parts A and B); and frequency of DLTs at each dose level (Part A). Secondary and exploratory endpoints include: objective response rate, disease control rate, duration of response, progression-free survival, characterization of PK by CAR-positive T cell counts, CAR transgene level in blood, effusions, and target tissues, and evaluation of immunogenicity by presence of anti-LB1908 antibodies. Acknowledgments: This study is funded by Legend Biotech USA Inc. Clinical trial information: NCT05539430 .

Biological correlative analyses and updated clinical data of ciltacabtagene autoleucel (cilta-cel), a BCMA-directed CAR-T cell therapy, in patients with multiple myeloma (MM) and early relapse after initial therapy: CARTITUDE-2, cohort B

8029

Background: In cohort B of the multicohort phase 2 CARTITUDE-2 (NCT04133636) study, the efficacy and safety of cilta-cel are being evaluated in patients (pts) with MM who had early relapse after initial therapy. These pts have functionally high-risk disease, with early relapse post autologous stem cell transplantation (ASCT) being a poor prognostic factor and representing an unmet medical need. We present updated results. Methods: Eligible pts had MM, received 1 prior LOT (PI and IMiD required), had disease progression per IMWG (either ≤12 mo after ASCT or ≤12 mo after start of anti-myeloma therapy for pts who did not undergo ASCT), and were tx-naive to CAR-T/anti-BCMA therapies. A single cilta-cel infusion (target dose 0.75×106 CAR+ viable T cells/kg) was given post lymphodepletion. Safety and efficacy were assessed, and the primary endpoint was MRD negativity at 10-5. Management strategies were implemented to minimize risk of movement/neurocognitive AEs (MNTs). Pharmacokinetic (PK) analyses (Cmax and Tmax of CAR+ T-cell transgene levels in blood) are being conducted, as well as analyses of levels of CRS-related cytokines (eg, IL-6) over time, peak levels of cytokines by response and CRS, association of cytokine levels with ICANS, and CAR+ T cell CD4/CD8 ratio by response, CRS, and ICANS. Results: As of January 2022, 19 pts (median age 58.0 y [range 44–67]; 74% male; median follow-up 13.4 mo [range 5.2–21.7]) received cilta-cel. 79% of pts received prior ASCT. ORR was 100.0%, 90% achieved CR or better, and 95% achieved ≥VGPR. Median time to first response and best response were 0.95 mo (range 0.9–9.7) and 5.1 mo (range 0.9–11.8), respectively. Of pts who were MRD-evaluable (n = 15), 14 (93%) achieved MRD 10-5 negativity during this study. Median DOR was not reached and 12-mo event-free rate was 88.9%. The 12-mo PFS rate was 90%. Median time to onset of CRS was 8 d (range 5–11) and occurred in 16 (84.2%) pts (1 gr 4). CRS resolved in all pts. ICANS (gr 1) occurred in 1 pt; MNT (gr 3) occurred in 1 pt, previously reported. 1 pt died post cilta-cel due to PD at d 158. Preliminary PK analyses indicate that peak expansion of CAR-T cells occurred on d 13.1 (range 8.96–209.9) and median persistence was 76.9 d (range 40.99–221.8). Conclusions: A single cilta-cel infusion led to deep and durable responses in a functionally high-risk pt population who experienced early clinical relapse/tx failure to initial therapy, with a manageable safety profile. In this pt population with ineffective or insufficient response to ASCT, cilta-cel led to responses. Responses continue to deepen, and follow-up is ongoing. Updated and in-depth PK, cytokine, and CAR-T subset analyses and clinical correlation will be presented and provide novel insights into biological correlates of efficacy and safety in this pt population. Clinical trial information: NCT04133636.

Expression of miR-4739 in Gastric cancer and its Relationship with Clinical Pathological Features of Patients

Objective

To investigate the expression level of miR-4739 in gastric cancer (GC), analyze its diagnostic value in GC and the relationship with clinical pathological characteristics, and analyze its impact on the prognosis of patients.

Methods

A total of 96 patients with GC who underwent radical gastrectomy in our hospital from March 2017 to June 2021 were selected. GC tissues from all patients were collected, and normal tissues adjacent to cancer were collected as controls. The expression level of miR-4739 in tissues was detected, the relationship between miR-4739 and different pathological features was analyzed, and the diagnostic value of miR-4739 in GC was analyzed. All patients were followed up after the operation, and the survival time of the patients was set as from the day of the first operation to 1 d when the patients died or the follow-up ended.

Results

The relative expression level of miR-4739 in the GC tissue was (0.39 ± 0.06), lower than that in the paracancerous tissue (1.18 ± 0.19) (P < 0.05). The AUC of miR-4739 in the diagnosis of GC was 0.705. When the Youden index was 0.320 and the optimal cutoff value was 0.37, the sensitivity was 95.30% and the specificity was 36.70%. The expression level of miR-4739 in our patient was related to the differentiation degree, lymph node metastasis, tumor diameter, and TNM stage (P < 0.05). During the follow-up period, 26 of 96 patients died, and the survival rate was 72.92% (26/96). The median survival time was 29 months in the miR-4739 LE group, which was shorter than 39 months in the miR-4739 HE group (P < 0.05). Univariate analysis showed that age, degree of differentiation, lymph node metastasis, tumor diameter, TNM staging, and miR-4739 expression were all related to the prognosis of the patient (P < 0.05). Multivariate analysis showed that differentiation degree, lymph node metastasis, tumor diameter, TNM staging, and miR-4739 expression were all independent factors affecting the prognosis of the patients (P < 0.05).

Conclusion

The expression of miR-4739 in GC tissue was down-regulated, and its level was related to the degree of differentiation, lymph node metastasis, tumor diameter, and TNM stage. The expression level of miR-4739 has certain diagnostic value for patients with GC, and the prognosis of patients in LE group was worse than that in HE group.

Anti-drug Antibody Validation Testing and Reporting Harmonization

Evolving immunogenicity assay performance expectations and a lack of harmonized anti-drug antibody validation testing and reporting tools have resulted in significant time spent by health authorities and sponsors on resolving filing queries. Following debate at the American Association of Pharmaceutical Sciences National Biotechnology Conference, a group was formed to address these gaps. Over the last 3 years, 44 members from 29 organizations (including 5 members from Europe and 10 members from FDA) discussed gaps in understanding immunogenicity assay requirements and have developed harmonization tools for use by industry scientists to facilitate filings to health authorities. Herein, this team provides testing and reporting strategies and tools for the following assessments: (1) pre-study validation cut point; (2) in-study cut points, including procedures for applying cut points to mixed populations; (3) system suitability control criteria for in-study plate acceptance; (4) assay sensitivity, including the selection of an appropriate low positive control; (5) specificity, including drug and target tolerance; (6) sample stability that reflects sample storage and handling conditions; (7) assay selectivity to matrix components, including hemolytic, lipemic, and disease state matrices; (8) domain specificity for multi-domain therapeutics; (9) and minimum required dilution and extraction-based sample processing for titer reporting.

Ciltacabtagene autoleucel, a B-cell maturation antigen-directed chimeric antigen receptor T-cell therapy in patients with relapsed or refractory multiple myeloma (CARTITUDE-1): a phase 1b/2 open-label study

BACKGROUND

CARTITUDE-1 aimed to assess the safety and clinical activity of ciltacabtagene autoleucel (cilta-cel), a chimeric antigen receptor T-cell therapy with two B-cell maturation antigen-targeting single-domain antibodies, in patients with relapsed or refractory multiple myeloma with poor prognosis.

METHODS

This single-arm, open-label, phase 1b/2 study done at 16 centres in the USA enrolled patients aged 18 years or older with a diagnosis of multiple myeloma and an Eastern Cooperative Oncology Group performance status score of 0 or 1, who received 3 or more previous lines of therapy or were double-refractory to a proteasome inhibitor and an immunomodulatory drug, and had received a proteasome inhibitor, immunomodulatory drug, and anti-CD38 antibody. A single cilta-cel infusion (target dose 0·75 × 10⁶ CAR-positive viable T cells per kg) was administered 5-7 days after start of lymphodepletion. The primary endpoints were safety and confirmation of the recommended phase 2 dose (phase 1b), and overall response rate (phase 2) in all patients who received treatment. Key secondary endpoints were duration of response and progression-free survival. This trial is registered with ClinicalTrials.gov, NCT03548207.

FINDINGS

Between July 16, 2018, and Oct 7, 2019, 113 patients were enrolled. 97 patients (29 in phase 1b and 68 in phase 2) received a cilta-cel infusion at the recommended phase 2 dose of 0·75 × 10⁶ CAR-positive viable T cells per kg. As of the Sept 1, 2020 clinical cutoff, median follow-up was 12·4 months (IQR 10·6-15·2). 97 patients with a median of six previous therapies received cilta-cel. Overall response rate was 97% (95% CI 91·2-99·4; 94 of 97 patients); 65 (67%) achieved stringent complete response; time to first response was 1 month (IQR 0·9-1·0). Responses deepened over time. Median duration of response was not reached (95% CI 15·9-not estimable), neither was progression-free survival (16·8-not estimable). The 12-month progression-free rate was 77% (95% CI 66·0-84·3) and overall survival rate was 89% (80·2-93·5). Haematological adverse events were common; grade 3-4 haematological adverse events were neutropenia (92 [95%] of 97 patients), anaemia (66 [68%]), leukopenia (59 [61%]), thrombocytopenia (58 [60%]), and lymphopenia (48 [50%]). Cytokine release syndrome occurred in 92 (95%) of 97 patients (4% were grade 3 or 4); with median time to onset of 7·0 days (IQR 5-8) and median duration of 4·0 days (IQR 3-6). Cytokine release syndrome resolved in all except one with grade 5 cytokine release syndrome and haemophagocytic lymphohistiocytosis. CAR T-cell neurotoxicity occurred in 20 (21%) patients (9% were grade 3 or 4). 14 deaths occurred in the study; six due to treatment-related adverse events, five due to progressive disease, and three due to treatment-unrelated adverse events.

INTERPRETATION

A single cilta-cel infusion at the target dose of 0·75 × 10⁶ CAR-positive viable T cells per kg led to early, deep, and durable responses in heavily pretreated patients with multiple myeloma with a manageable safety profile. The data from this study formed the basis for recent regulatory submissions.

FUNDING

Janssen Research & Development and Legend Biotech.

Incidence, mitigation, and management of neurologic adverse events in patients with multiple myeloma (MM) treated with ciltacabtagene autoleucel (cilta-cel) in CARTITUDE-2

8028

Background: Cilta-cel (JNJ-68284528) is a chimeric antigen receptor T (CAR-T)-cell therapy with 2 BCMA-targeting, single-domain antibodies designed to confer high avidity binding. CARTITUDE-2 (NCT04133636) is a phase 2, multicohort, open-label study assessing the efficacy and safety of cilta-cel in patients (pts) with MM in various clinical settings. Here, we describe the mitigation and management strategies implemented to identify and reduce the risk for neurologic adverse events (AEs) in Cohort A pts (progressive MM after 1−3 prior lines of therapy). Methods: Eligible pts (≥18 years of age) had MM per IMWG criteria, measurable disease, ECOG ≤1, progressive disease after 1−3 prior lines of therapy (including a PI and IMiD) and were lenalidomide refractory (no prior BCMA-targeting agent). Cilta-cel (0.75×106 [range 0.5–1.0×106] CAR+ viable T cells/kg) was given as a single infusion 5–7 days after start of lymphodepletion (cyclophosphamide 300 mg/m2 + fludarabine 30 mg/m2 daily for 3 days). Monitoring and mitigation strategies for neurologic AEs include providing more effective bridging therapy to reduce tumor burden prior to lymphodepletion, frequent assessment of CAR-T-related ICANS using the ICE tool, regular handwriting assessments to detect micrographia, and neuroimaging (brain MRI) and EEG for pts with prior neurologic disease. Management strategies include evaluating infectious and paraneoplastic etiologies upon observation of ICANS ≥Grade (gr) 1, administration of tocilizumab (if concurrent CRS, all gr of ICANS) and/or dexamethasone (gr 2/3) or methylprednisolone (gr 4). ICANS and CRS were graded by ASTCT criteria; neurotoxicities not classified as ICANS were graded per CTCAE Version 5.0. Results: As of 15 Jan 2021 (median follow-up: 5.8 months [range: 2.5–9.8 months]), 20 pts in Cohort A received cilta-cel. Median age was 60 years (range: 38–75); 65% were male. Neurotoxicities occurred in 4 pts (20%). Three pts had ICANS (gr 1/2); median time to onset of symptoms was 8 days (range: 7–11) and median duration was 2 days (range: 1–2). Two of the 3 pts received supportive measures to treat ICANS, including levetiracetam and steroids; all 3 had concurrent CRS and all recovered. One pt developed isolated facial paralysis (gr 2) on Day 29 after cilta-cel infusion, and recovered 51 days after the onset of event following treatment with dexamethasone for 28 days. No movement or neurocognitive disorders were reported. Conclusions: Neurologic AEs were generally manageable in pts with MM following treatment with cilta-cel. With a median of 5.8 months of follow-up, there were no movement or neurocognitive disorders in pts from Cohort A. These results suggest that early detection and management of neurologic AEs can lead to better treatment outcomes. Clinical trial information: NCT04133636.

Preclinical analysis of an autologous CD4-targeted chimeric antigen receptor T-cell (CAR-T) immunotherapy for relapsed or refractory peripheral T-cell lymphoma (PTCL) or cutaneous T-cell lymphoma (CTCL)

e14510

Background: CD4 is highly and uniformly expressed T-cell lymphomas (TCL) including PTCL and CTCL, suggesting its potential as a surface target for CAR-T therapy. However, there is a significant risk of potential antigen masking by CAR introduced into tumor cells, which thereby leads to escape of tumor cells from recognition by CAR-T cells. For example, Ruella M et al ( Nat Med, 2018) reported that contaminating malignant B cells transduced with anti-CD19 CAR (called CAR-B cells) in the manufacturing process led to the CD19 antigen masking by CAR molecules. Hence, CAR-B tumor cells could not be recognized by CAR-T cells, which resulted in relapse of CAR expressing B lymphoma cells. A similar antigen masking effect might occur for the anti-CD4 CAR-T product. Methods: To identify single-chain variable fragment (scFv) without antigen-masking effect, large panels of fully human monoclonal antibodies were converted to format of CAR modality with the scFv-4-1BB-CD3z structure and introduced into CD4+ and CD8+ T cells. After lentiviral transduction, residual CD4+ T cells were quantified and the CARs with complete elimination of CD4+ T cells were selected for further validation. The selected CAR constructs were then introduced into CD4+ TCL cells HH (CAR-HH cells) to mimic the potential risk of introducing CAR into contaminating malignant T cells in the manufacturing process. Thereafter, CAR-HH cells were subject to in vitro killing assay by LB1901. Last, identified CAR constructs were further tested for in vitro and in vivo anti-tumor efficacy and off-target binding and killing. Results: Introduction of LB1901 CAR into CD4+ and CD8+ T cells led to complete elimination of CD4+ T cells, suggesting no masking effect of CAR on CD4 antigen. Furthermore, the introduction of CAR into CD4+ HH cells did not protect HH cells from being recognized and eliminated by LB1901, further confirming that the CAR modality of LB1901 does not mask CD4 antigen. An in vivo anti-tumor efficacy study showed that LB1901 exhibited dose-dependent anti-tumor activity without significant adverse effect. As low as 0.3 million CAR+ cells completely suppressed tumor growth, suggesting the potent anti-tumor activity by LB1901. Immunohistochemical analysis of normal tissues with LB1901 scFV binder showed no off-target binding. Furthermore, no killing toward CD4- cell lines and primary cells derived from vital organs or antigen-independent cytokine release was observed in vitro. Conclusions: Altogether, the in vitro and in vivo studies showed that LB1901 did not “mask” the CD4 antigen but exhibited potent anti-tumor activity without off-target effects. A phase 1 study of LB1901 CAR-T in patients with relapsed or refractory PTCL or CTCL is ongoing in the US to assess the safety and tolerability of LB1901 CAR-T (NCT04712864).

Volumetric absorptive microsampling (VAMS®) in therapeutic protein quantification by LC-MS/MS: Investigation of anticoagulant impact on assay performance and recommendations for best practices in method development

Microsampling techniques have been employed as an alternative to traditional serum/plasma sampling because of their inherently proven and desirable advantages across the pharmaceutical industry. These include reduced animal usage in pre-clinical studies, as well as, permitting the collection of samples that would otherwise be inaccessible in clinical studies. The application of volumetric absorptive microsampling (VAMS®) technology, a second-generation dried microsampling method, coupled with LC-MS, has been extensively explored for small molecule drugs at various drug development stages. However, the potential of using VAMS technology and LC-MS analysis for biological therapeutic development has yet to be well-established. In this work, we describe the method development, validation, and a proof-of-concept non-human primate study of a LC-MS/MS method for VAMS utilized to obtain pharmacokinetic (PK) data for a therapeutic monoclonal antibody. A good correlation between VAMS data and data from conventional serum samples was established in rhesus monkeys and indicated the possibility of using of this novel sampling technology in clinical studies. However, during the initial clinical study, a significant difference in internal standard (IS) response between the patient fingerstick samples and the standard/QC samples was observed, which posed a question on the accuracy of the clinical results. A comprehensive investigation confirmed that the EDTA anticoagulant used in the standard/QC samples was the root cause of the observed anomalous IS responses. Special considerations and corresponding best practices during method development and validation are proposed to ensure early detection of potential issues and appropriate implementation of VAMS technology in clinical studies in the future.

Correlations between microbiota and metabolites after faecal microbiota transfer in irritable bowel syndrome

Faecal microbiota transfer (FMT) consists of the infusion of donor faecal material into the intestine of a patient with the aim to restore a disturbed gut microbiota. In this study, it was investigated whether FMT has an effect on faecal microbial composition, its functional capacity, faecal metabolite profiles and their interactions in 16 irritable bowel syndrome (IBS) patients. Faecal samples from eight different time points before and until six months after allogenic FMT (faecal material from a healthy donor) as well as autologous FMT (own faecal material) were analysed by 16S RNA gene amplicon sequencing and gas chromatography coupled to mass spectrometry (GS-MS). The results showed that the allogenic FMT resulted in alterations in the microbial composition that were detectable up to six months, whereas after autologous FMT this was not the case. Similar results were found for the functional profiles, which were predicted from the phylogenetic sequencing data. While both allogenic FMT as well as autologous FMT did not have an effect on the faecal metabolites measured in this study, correlations between the microbial composition and the metabolites showed that the microbe-metabolite interactions seemed to be disrupted after allogenic FMT compared to autologous FMT. This shows that FMT can lead to altered interactions between the gut microbiota and its metabolites in IBS patients. Further research should investigate if and how this affects efficacy of FMT treatments.

Update of CARTITUDE-1: A phase Ib/II study of JNJ-4528, a B-cell maturation antigen (BCMA)-directed CAR-T-cell therapy, in relapsed/refractory multiple myeloma

8505

Background: JNJ-68284528 (JNJ-4528) is a chimeric antigen receptor T (CAR-T) cell therapy containing 2 BCMA-targeting single-domain antibodies. Here we present updated CARTITUDE-1 (NCT03548207) phase 1b results with longer follow-up. Methods: Pts had MM per IMWG criteria, measurable disease, received ≥3 prior regimens or were double refractory to a PI and IMiD, and received anti-CD38 antibody. Cyclophosphamide 300 mg/m2+ fludarabine 30 mg/m2 over 3 days were used for lymphodepletion. JNJ-4528 (median, 0.73x106 CAR+ viable T cells/kg) was given as a single infusion. Cytokine release syndrome (CRS) was graded by Lee et al2014 and neurotoxicity by CTCAE, v5.0 and ASTCT grading. Response was assessed per IMWG criteria. Results: As of 17 Jan 2020, median follow-up is 9 mo (3–17). Phase 1b enrollment is complete (N = 29 treated; median 5 (3–18) prior lines, 76% penta-exposed, 86% triple-refractory, 31% penta-refractory, 97% refractory to last line of therapy). Most frequent adverse events (AEs) were neutropenia (100%), CRS (93%), and thrombocytopenia (93%). Grade (Gr) ≥3 hematologic AEs were neutropenia (100%), thrombocytopenia (69%), and leukopenia (59%). 27 (93%) pts had CRS; 25 Gr 1–2, 1 Gr 3, and 1 Gr 5 (day 99 subsequent to dose-limiting toxicity of prolonged Gr 4 CRS). Median time to onset of CRS was 7 days (2–12). 4 pts had treatment-related neurotoxicity: 3 Gr 1–2 and 1 Gr 3. ORR was 100%, with 22 (76%) stringent complete responses (sCRs), 6 (21%) very good partial responses (VGPRs), and 1 (3%) PR. Median time to ≥CR was 2 mo (1–9). 26/29 pts are progression-free, with 6-mo progression-free survival rate of 93% and longest response ongoing at 15 mo. 1 death due to CRS and 1 to acute myeloid leukemia (not treatment-related) occurred during the study. All 16 pts (14 sCR, 2 VGPR) evaluable at 6 mo were minimal residual disease negative at 10−5 or 10−6. JNJ-4528 CAR+ T cell expansion peaked between day 10–14. At 6-mo individual follow-up, 22/28 pts had JNJ-4528 CAR+ T cells below the level of quantification (2 cells/µL) in peripheral blood, suggesting CAR-T persistence in peripheral blood did not seem to correlate with deepening of response. At peak expansion, preferential expansion of CD8+ CAR-T cells with a central memory phenotype was observed in peripheral blood. Conclusions: JNJ-4528 treatment led to responses in all pts. These responses were early, deep, and durable at a low dose of CAR-T cells with 26/29 (90%) pts progression free at median 9-mo follow-up. CRS was manageable in most pts, supporting outpatient dosing. Clinical trial information: NCT03548207 .

The study on pathological mechanism and solution method for spinal cord ischemia reperfusion injury

OBJECTIVE

We aimed at investigating the pathological mechanism changing of injury during reperfusion injury, reperfusion time correlation and compliance, finding the blood supply and improving the secondary damage.

MATERIALS AND METHODS

A total of 180 patients who underwent a surgical procedure and that received normal saline intraperitoneally immediately after the patients' aortic occlusions were investigated. Patients were divided in three groups. Experimental conditions and programs were designed for various approaches.

RESULTS

Thirty min after the onset of ischemia, we found a decrease in the local blood flow in the lumbar spinal cord, almost -77.48% of the baseline, which was reversed partially by initial reperfusion, even exceeding the baseline level. However, 1 hour after reperfusion, the blood flow was again decreased to the level below the baseline, followed by a decline to 207.13% ± 38.25 PU for 3 h without any recovery. Attenuating this secondary damage with neuroprotective strategies requires an understanding of these pathophysiologic processes.

CONCLUSIONS

This study showed the pathological mechanism changes during reperfusion injury and reperfusion time correlation and compliance, and analyzed some of the important pathophysiologic processes involved in secondary damage after spinal cord injury. Moreover, our research discusses a number of pharmacologic therapies that have either been studied or have future potential for this devastating injury.

Effects of zoledronic acid on bone mineral density around prostheses and bone metabolism markers after primary total hip arthroplasty in females with postmenopausal osteoporosis

INTRODUCTION

To investigate the effect of zoledronic acid on periprosthetic bone mineral density (BMD) and bone metabolism markers after primary total hip arthroplasty in females with postmenopausal osteoporosis.

METHODS

From November 2015 to April 2016, 40 female patients who met the inclusion criteria were randomized into two groups: a control group (calcium + calcitriol) and a zoledronic acid group (calcium + calcitriol + zoledronic acid). At 1 week and 3, 6, and 12 months after operation, BMD was obtained through dual-energy X-ray absorptiometry (DEXA). At pre-operation and at 3, 6, and 12 months after the operation, levels of bone metabolism markers were obtained by serum examination.

RESULTS

Loss of BMD was significantly more pronounced in the control group than in the ZOL group in zones 1, 4, 6, and 7 at 6 months and in zones 1, 2, 4, 6, and 7 at 12 months after the operation. The levels of bone-resorption marker (β-CTX) were significantly lower in the ZOL group than in the control group at 3, 6, and 12 months after operation. The levels of bone-formation marker (TP1NP) performed statistically differences only at 12 months after the operation in these two groups.

CONCLUSIONS

Receiving an intravenous infusion of 5 mg zoledronic acid after THA can effectively reduce periprosthetic BMD loss and improve bone remodeling in females with postmenopausal osteoporosis. Zoledronic acid significantly inhibited bone mass loss in zones 1, 2, 4, 6, and 7 after THA and inhibited bone-resorption marker (β-CTX) to improve bone remodeling. Zoledronic acid treatment is potentially important for patients with osteoporosis after THA.

Association of serum galectin-3 with risks of death and vascular events in acute ischaemic stroke patients: the role of hyperglycemia

BACKGROUND AND PURPOSE

Whether the association between galectin-3 and stroke outcome is modified by fasting plasma glucose (FPG) is unknown. The aim was to evaluate the prognostic effect of galectin-3 amongst ischaemic stroke patients stratified by FPG.

METHODS

In all, 3082 ischaemic stroke patients were included in this study and serum galectin-3 was tested at baseline. The primary outcome was a composite outcome of death and vascular events, and secondary outcomes were death, stroke recurrence and vascular events within 1 year after stroke.

RESULTS

Increased galectin-3 was significantly associated with the primary outcome, stroke recurrence and vascular events in the patients with hyperglycemia but not in those with normoglycemia (P for interaction < 0.05 for all). The multivariate-adjusted hazard ratios (95% confidence intervals) were 1.72 (1.05-2.84), 2.64 (1.14-6.12) and 2.68 (1.33-5.38) for the primary outcome, stroke recurrence and vascular events, respectively. A linear association between galectin-3 and the primary outcome was observed in hyperglycemic patients (P for linearity = 0.007).

CONCLUSION

Increased galectin-3 was associated with the primary outcome, stroke recurrence and vascular events within 1 year after stroke in the patients with hyperglycemia, suggesting that galectin-3 may be an important prognostic factor for ischaemic stroke patients with hyperglycemia.

1971. A Randomized, Double-Blind, Placebo-Controlled Trial to Assess the Safety and Tolerability of a Respiratory Syncytial Virus (RSV) Neutralizing Monoclonal Antibody (MK-1654) in Healthy Subjects

Background

Respiratory syncytial virus (RSV) is the most common cause of lower respiratory tract infection and hospitalization in infants. Prophylaxis for RSV infection is only recommended for the highest risk infants, leaving the majority of infants unprotected. MK-1654 is a fully human monoclonal antibody targeting the RSV fusion (F) protein with Fc domain mutations to extend half-life that is being developed to provide passive immunity against RSV in infants. The safety profile, development of anti-drug antibodies (ADAs), serum neutralizing antibody (SNA) titers, and pharmacokinetics (PK) in healthy adult volunteers receiving single-ascending doses of MK-1654 was evaluated.

Methods

In this double-blinded ongoing Phase 1 study, healthy adults of non-childbearing potential (19 to 59 years) were randomized in a 3:1 ratio to receive a single dose of MK-1654 or placebo (0.9% sodium chloride injection, USP) as a bolus intramuscular injection (IM) or in an intravenous infusion (IV) for at least 2.5 hours. Dose levels included 100 and 300 mg IM, and 300, 1,000, and 3,000 mg IV. Standard methods were used to assess safety and tolerability. Serum was tested for ADAs and RSV A SNA titers at time points up to day 120 and up to day 90, respectively. MK-1654 adult PK and estimated PK for infants will be reported separately.

Results

A total of 152 subjects (male = 117, female = 35) have been enrolled (mean age = 41 years). No deaths, serious adverse events, discontinuations due to AEs, clinically significant laboratory AEs, or dose-dependent pattern of drug-related AEs were reported. Sixty-six subjects reported 181 clinical AEs (97.8% mild and 2.2% moderate in intensity). The most common AEs (≥5%) were headache, nasal congestion, vessel puncture site hemorrhage, oropharyngeal pain, rhinorrhea and nausea. No treatment emergent ADAs have been identified through time points tested. Administration of MK-1654 resulted in a dose-dependent increase in RSV A SNA titers through Day 90 (figure). Updated safety, SNA titers and ADAs will be provided.

Conclusion

MK-1654 was generally well tolerated at doses up to 300 mg IM and up to 3,000 mg IV and resulted in a dose-dependent increase in SNA titers, reflecting biologically active MK-1654 in the serum. No treatment emergent ADAs have been observed.

Disclosures

A. Aliprantis, Merck: Employee and Shareholder, Salary and stock options. D. Wolford, Merck: Employee and Shareholder, Salary and stock options. L. Caro, Merck: Employee and Shareholder, Salary and stock options. B. Maas, Merck: Employee and Shareholder, Salary and stock options. H. Ma, Merck: Employee and Shareholder, Salary and stock options. K. Vora, Merck: Employee, Salary. D. Geng, Merck: Employee and Shareholder, Salary and stock options. R. Railkar, Merck: Employee and Shareholder, Salary and stock options. A. Lee, Merck: Employee and Shareholder, Salary and stock options. L. Sterling, Merck: Investigator, Research grant. E. Lai, Merck: Employee and Shareholder, Salary and stock options.

1384. RSV Monoclonal Antibody (MK-1654) Phase 1 Pharmacokinetics (PK) in Healthy Adults and Population PK Modeling to Support Pediatric Development

Background

Respiratory syncytial virus (RSV) is the most common cause of lower respiratory tract infection and hospitalization in infants. MK-1654 is a monoclonal antibody (mAb) being developed to prevent RSV infection in infants and is undergoing evaluation in a Phase 1 study. Incorporation of YTE mutations extend its half-life to allow for dosing once every RSV season. Preliminary Phase 1 PK results and the development of a population PK model that characterizes adult PK to predict pediatric exposures are presented here.

Methods

In this double-blinded Phase 1 study, 152 healthy males and females of nonchildbearing potential aged 19–59 years were randomized in a 3:1 ratio to receive a single dose of MK-1654 or placebo as a bolus intramuscular injection (IM) or in an intravenous infusion (IV) over 2.5 hours. Dose levels included 100 mg IM, 300 mg IM, 300 mg IV, 1,000 mg IV and 3,000 mg IV. Serial serum samples were collected to measure MK-1654 PK via a validated LC/MS assay. A noncompartmental PK analysis was conducted using preliminary data from 60 subjects up to Day 150 (900 observations). A population PK model was developed to simultaneously characterize the IM and IV adult PK data and to predict pediatric PK through allometric scaling. Pediatric MK-1654 PK was predicted for several IM doses for a typical sized infant (35 weeks gestational age at birth; 4 months chronological age at dosing; 50th percentile weight).

Results

In adults, the median time to maximum concentration observed was ~6–10 days following IM injection. The apparent half-life of MK-1654 ranged from ~70–85 days after either IM or IV doses. The estimated IM bioavailability was ~71%. C_max and AUC_{0-90 days} increased dose proportionally following IV administration. MK-1654 adult PK was best characterized using a two-compartment model with first-order elimination. IM absorption was described using a first-order rate constant with lag time. Inter-individual variability was included for clearance (CL and Q), central volume (V2), and absorption rate (Ka). The pediatric model suggested apparent terminal half-life in a typical infant is shorter than adults, likely being driven by infant growth during treatment.

Conclusion

Predicted infant PK profiles support further development of MK-1654 in children.

Disclosures

B. Maas, Merck: Employee and Shareholder, Salary and stock options. A. Aliprantis, Merck: Employee and Shareholder, Salary and stock options. D. Wolford, Merck: Employee and Shareholder, Salary and stock options. G. Fayad, Merck: Employee and Shareholder, Salary and stock options. K. Vora, Merck: Employee, Salary. D. Geng, Merck: Employee and Shareholder, Salary and stock options. H. Ma, Merck: Employee and Shareholder, Salary and stock options. L. Caro, Merck: Employee and Shareholder, Salary and stock options.

Associations Between Selenium Content in Hair and Kashin-Beck Disease/Keshan Disease in Children in Northwestern China: a Prospective Cohort Study

The objective of this study was to investigate the relationship between selenium content in hair and the incidence of Kashin-Beck disease (KBD) and Keshan disease (KD) in China. A prospective cohort study was conducted among children aged 5-12 years with different levels of low-selenium (group 1, Se ≤ 110 ng/g; group 2, 110 < Se ≤ 150 ng/g; and group 3, 150 < Se ≤ 200 ng/g) or selenium-supplemented (group 4, Se > 200 ng/g) exposure. A person-years approach was used to calculate the incidence and rate of positive clinical signs. Relative risk (RR), attributable risk, and etiologic fraction were used to determine the strength of association between selenium and disease incidence. Seven new KBD cases were diagnosed during 3-year follow-up. Positive clinical signs of KBD were found in 17.78 (95% confidence interval [CI] 14.27-21.29) cases per 100 person-years in group 1, 13.28 (9.82-16.74) in group 2, 12.95 (9.34-16.56) in group 3, and 8.18 (5.50-10.85) in group 4. Compared with group 4, the RR (95% CI) of groups 1, 2, and 3 were 2.17 (1.48-3.19), 1.62 (1.07-2.47), and 1.58 (1.03-2.43), respectively. Positive clinical signs of KD were 25.90 (18.62-33.18) cases per 100 person-years in group 1, 5.66 (1.26-10.06) in group 2, 4.60 (0.20-9.00) in group 3, and 14.62 (8.54-20.69) in group 4. Compared with group 4, the RR (95% CI) were 1.77 (1.07-2.93), 0.39 (0.16-0.93), and 0.31 (0.11-0.89), respectively. In children, the onset of KBD was negatively correlated with selenium content within a certain range. However, there may be a U-shaped association between selenium content and KD in children.

Serum 25-hydroxyvitamin D deficiency predicts poor outcome amongst acute ischaemic stroke patients with low high density lipoprotein cholesterol

BACKGROUND AND PURPOSE

Current observational studies indicate that a lower vitamin D level is associated with a higher risk of poor ischaemic stroke prognosis. Whether this association is affected by lipid levels is unclear. Our aim was to examine the effect of serum vitamin D especially its deficiency on the global outcome of ischaemic stroke stratified by individual lipid component level.

METHODS

A total of 3181 ischaemic patients from China Antihypertensive Trial in Acute Ischaemic Stroke were included in this study and their baseline serum 25-hydroxyvitamin D levels were tested. They were prospectively followed up for death, major disability and vascular events for 3 months after acute ischaemic stroke. A multivariable logistic model was used to evaluate the association between serum 25-hydroxyvitamin D levels and clinical outcomes of ischaemic stroke in the 3-month period of follow-up in all patients and in different lipid-level subgroups.

RESULTS

Vitamin D deficiency was associated with poor clinical outcomes only in ischaemic stroke patients with high density lipoprotein cholesterol (HDLC) <1.04 mmol/l rather than all patients. The multivariable adjusted odds ratios (95% confidence intervals) of major disability and composite adverse events were 1.98 (1.08-3.63) and 2.24 (1.22-4.12), respectively. There was a significant interaction effect between vitamin D and HDLC levels on major disability and the composite outcome (P for interaction < 0.05 for both). A significant linear trend existed between 25-hydroxyvitamin D and risk of poor prognosis (P = 0.03).

CONCLUSIONS

Vitamin D deficiency may be merely an independent risk factor of poor prognosis in ischaemic stroke patients with low HDLC level.

Effect of single nucleotide polymorphisms in the ATP-binding cassette B1 gene on the clinical outcome of traumatic brain injury

The critical role of ATP-binding cassette B1 (ABCB1) in the function of the blood-brain barrier led us to conducted this prospective study in order to investigate the clinical outcome of patients suffering from severe traumatic brain injury. A total of 182 patients with traumatic brain injury were included in our study. Genotyping of ABCB1 C3435T and G2677T/A was conducted using polymerase chain reaction-restriction fragment length polymorphism. Using multivariate-logistic regression analysis, we found that patients carrying the CT+CC genotype of ABCB1 C3435T were more likely to have a better neurological outcome when compared with the TT genotype (odds ratio = 2.71, 95% confidence interval = 1.12-6.86). However, no significant association was found between the G2677T/A polymorphism and outcome of traumatic brain injury patients. Our study provides important information regarding the prognostic value of ABCB1 C3435T, and the ABCB1 C3435T polymorphism may be used as a predictive marker for the outcome of traumatic brain injury patients.

Clinical significance of fibroblast growth factor receptor-3 mutations in bladder cancer: a systematic review and meta-analysis

Mutations in the fibroblast growth factor receptor-3 (FGFR3) gene are frequently found in bladder cancer, but their prognostic value remains controversial. To globally summarize the association between FGFR3 mutations and the grade and stage of bladder cancer, and to analyze the predictive role of FGFR3 mutations with respect to survival, eligible studies were identified and assessed for quality through multiple search strategies. Risk ratio (RR) data were collected from studies comparing the number of FGFR3 mutants among low-grade and early-stage bladder cancer patients to the number among high-grade and late-stage patients. Hazard ratio (HR) data were collected from studies comparing survival in patients with mutant FGFR3 genes to those with wild-type genes. Studies were pooled, and the RRs of grade and stage and the HRs of survival were calculated. Thirty studies were included in the present meta-analysis. FGFR3 mutations were found to be closely associated with low-grade and early-stage bladder cancer, showing pooled RRs = 2.948 [95% confidence interval (CI) = 2.357-3.688] and 2.845 (95%CI = 2.145- 3.773), respectively. Notably, patients with FGFR3 mutations tended to show better disease-, progress-, and recurrence-free survival (HR = 0.561, 95%CI = 0.405-0.779), and better disease-specific survival (HR = 0.363, 95%CI = 0.266-0.496). This study demonstrated that FGFR3 mutations are closely related to low grade, early stage, and better survival among bladder cancer patients.

Effects of a Cannabinoid Receptor 2 Selective Antagonist on the Inflammatory Reaction to Titanium Particles In Vivo and In Vitro

Wear particle-induced inflammation is a major factor contributing to aseptic loosening in peri-prosthetic tissue. The effects of cannabinoid receptor 2 (CB2) on wear particle-induced inflammation remain unclear. Reverse transcription–polymerase chain reaction and enzyme-linked immunosorbent assay were used to assess the effects of a CB2-selective antagonist, AM630, on regulation of the inflammatory reaction and production of pro-inflammatory cytokines in response to in vitro and in vivo stimulation with titanium particles. In vitro studies, in a model for pre-osteoclast-like cells, demonstrated that AM630 inactivation of CB2 profoundly inhibited interleukin (IL)-1β and tumour necrosis factor (TNF)-α production by RAW264.7 cells stimulated with titanium particles. In vivo findings in a murine air-pouch model of titanium-induced inflammatory osteolysis indicated that AM630 reduced titanium-induced tissue inflammation, seen as a reduction in pouch membrane thickness, inflammatory infiltration and levels of the pro-inflammatory cytokines IL-1β and TNF-α. Thus, inactivation of CB2 by AM630 inhibited the titanium particle-induced inflammatory reaction by reducing pro-inflammatory cytokines in vitro and in vivo.

Hypothalamus syndrome in opticospinal multiple sclerosis

This study describes a case of a patient with OSMS who presented with somnolence, periodic fever, memory impairment, and amenorrhea. Serum prolactin levels were found to be higher than normal. MR imaging showed a bilateral involvement of the hypothalamus. The clinical presentation, laboratory examination, and MR imaging findings suggested a diagnosis of hypothalamus syndrome in this patient.

Effect of combined treatment with methylprednisolone and Nogo-A monoclonal antibody after rat spinal cord injury

The purpose of this study was to investigate the effects of combination therapy with methylprednisolone (MP) and Nogo-66 antagonistic peptide (NEP1-40) on morphological and functional recovery in adult rats subjected to thoracic compression spinal cord injury (SCI). Animals were randomized into four groups: a trauma control group, an MP group, an NEP1-40 group, and a combined treatment group. The inflammatory reaction, neuronal and oligodendrocyte survival, and ultrastructure were assessed at the injury site. Functional analysis was also performed using Basso, Beattie and Bresnahan (BBB) scoring. Rat behaviour was evaluated regularly up to week 4. NEP1-40 did not alter the beneficial effect of MP on haematogenous inflammatory cell infiltration, while combined treatment resulted in greater neuronal and oligodendrocyte survival compared with monotherapy or control. Combination therapy resulted in better locomotor scores. These results in a clinically-relevant SCI model showed that significant neuroprotection can be obtained by combining an initial acute IV injection of MP with continuously infused NEP1-40.

[Effect of a traditional Chinese medicine compound on chronic heart failure in guinea-pigs]

OBJECTIVE

To investigate the effect of a traditional Chinese medicine compound (CTMC) on chronic heart failure (CHF) in guinea-pigs.

METHODS

The CHF of guinea-pigs were induced by repeated injection of hyodemic isoproterenol. The hemodynamics, organ (heart, lung, liver and kidney)/body weight ratio, pathological changes, and serum cTn-I and CK-MB were measured to determine the effectiveness of the traditional Chinese medicine treatement.

RESULTS

The LVDP and LVEDP were decreased and the absolute value of + dp/dt(max) and - dp/ dt(max) were increased by the administration of 10 mg/kg, 20 mg/kg and 30 mg/kg of the compound tablets. The effect increased with doses. The traditional Chinese medicine also decreased the area of myocardial necrosis and the degree of injury to myocardiacyte. The intervention group had lower serum cTn-I and CK-MB levels than the controls.

CONCLUSION

The compound tablets can improve the left ventricular diastolic function of CHF and reduce the myocardial damage in a dose-dependent manner.

[Genetic polymorphism of 15 STR on chromosome 2 and 11 in Shaanxi Han people in China]

OBJECTIVE

To investigate the genetic polymorphism of 15 short tandem repeat(STR)loci on chromosome 2 and chromosome 11 in Shaanxi Han people in China.

METHODS

Fluorescence-based gene scan technique was used to examine the genetic polymorphism of 15 STR loci in 175 unrelated individuals from Chinese Han population in Shannxi province.

RESULTS

The number of alleles D2S335, D2S396, D2S338, D2S2382, D2S305, D2S151, D2S2368, D2S391,D11S912, D11S4090, D11S4147, D11S4190, D11S4149, D11S4126, and D11S4094 was 11,11,11,10,8,8,9,12 ,7,11,8,10,5,5, and 6. The distribution of allele frequencies of the 15 STR was consistent with Hard-Weinberg equilibrium (P > 0.05). Heterozygosity (H) value was 0.4216 to approximately 0.8517, the average power of discrimination (DP) was 0.6568 to approximately 0.9598, polymorphism information content (PIC) was 0.4078 to approximately 0.8366, and probability of paternity exclusion (EPP) was 0.3135 to approximately 0.8537.

CONCLUSION

The 15 STR loci have relatively high genetic polymorphism in Shaanxi Han population, which provides the genetic structure of Chinese Han groups, and is also useful in anthropology and forensic science.

Detection of serum proteomic changes and discovery of serum biomarkers for Kashin-Beck disease using surface-enhanced laser desorption ionization mass spectrometry (SELDI-TOF MS)

The purpose of the current study was to investigate the changes of serum proteome and discover potential biomarkers for Kashin-Beck disease (KBD) using surface-enhanced laser desorption ionization mass spectrometry (SELDI-TOF MS). The serum protein profiles from 102 cases (36 KBD patients, 16 controls in KBD areas, 33 controls in non-KBD areas, and 17 osteoarthritis controls) were detected by SELDI-TOF MS and weak cation-exchange protein chip. Differently expressed peaks in KBD were identified by comparing the data among the four groups using the nonparametric Mann-Whitney test with Bonferroni correction at a significance level of 0.05. Then, those 102 cases were used to generate a classification tree as the training set, and an additional 34 cases were collected as the test set. A classification tree was generated by Biomarker Patterns Software (Ciphergen). Multiple protein changes were detected in the KBD group, including three potential biomarkers (15 886, 5336, 6113 m/z). A classification tree with three distinct proteins was generated. The classification tree was able to distinguish the KBD patients from the controls with 88.89% specificity and 86.36% sensitivity. The study demonstrates that marked serum proteomic changes exist in KBD. The proteins represented by the differently expressed peaks are candidate biomarkers for KBD.

Isolation of human anti-idiotypic antibodies by phage display for clinical immune response assays

The clinical development of therapeutic proteins requires assays that measure the pharmacokinetic (PK) profile of, and the potential immune response (IR) to, the protein agent. Each assay requires reagents that are highly specific for the therapeutic protein. For therapeutic monoclonal antibodies, anti-CDR-specific, or anti-idiotypic (anti-id), antibodies are an ideal class of reagents suitable for these assays because of their high specificity and affinity to the drug antibody. We generated anti-ids to two human antibodies by antibody phage display using the MorphoSys HuCAL GOLD Fab library. To selectively target the CDR regions, serum and a framework-matched mAb were included as competitors during the phage selection process. Panels of CDR-specific Fabs, with low to sub-nM affinities, were isolated against both targets. The CDR specificity of these Fabs was shown by their lack of binding to a framework-matched control mAb and by competition of this binding with the soluble antigens of the respective therapeutic mAb targets. The candidate anti-id Fabs were able to detect both immobilized and soluble target Ab without being affected by serum, a requirement for both PK assay and the IR bridging assay format. Combinations of the Fabs for PK detection assays were identified by pairwise binding studies, although the pair for one target mAb lacks the desired sensitivity for PK assays. To evaluate their potential as anti-drug antibodies (ADAs), the best Fabs for one of the targets were converted and produced as the required bivalent human mAbs. In comparison to rodent mAbs and primate polyclonal serum, the phage display derived human mAbs were equally effective as reference standards. Our results demonstrate that competition-based phage selection can be an effective method for the isolation of anti-idiotypic antibodies for PK and IR assay development, and in this latter case, overcome limitations of current methods using rodent derived anti-ids.

Effects of selenium and iodine deficiency on bone, cartilage growth plate and chondrocyte differentiation in two generations of rats

OBJECTIVE

The purpose of the current study was to investigate the roles of combined selenium and iodine deficiency in bone development as a possible experimental model of Kashin-Beck osteoarthropathy.

METHODS

Sprague-Dawley rats (n=48) were randomly divided into selenium deficiency (-Se+I), iodine deficiency (+Se-I), combined selenium and iodine deficiency (-Se-I), and selenium and iodine sufficient (+Se+I) groups. Growth of bone and cartilage, and the expression of type X collagen (ColX) and parathyroid hormone-related peptide (PTHrP) were measured in two generations of rats (F(0) and F(1)).

RESULTS

The tibial length in -Se-I rats was significantly shorter in F(1) generation. In +Se-I of F(1) rats, the thickness of the growth plate cartilage, and the proliferative zone was smaller, while in -Se-I rats the growth plate, and the proliferative and hypertrophic zones were also thinner in F(1) generation. In articular cartilage, ColX expression was increased in the deep zone in -Se-I rats of F(0) generation, and in -Se+I, +Se-I and -Se-I rats of F(1) generation. PTHrP expression was increased in the middle zone of -Se+I, +Se-I and -Se-I rats of both F(0) and F(1) generations. In the growth plate cartilage, ColX and PTHrP were expressed in the hypertrophic zone. ColX expression was significantly weaker in -Se+I and -Se-I rats in both F(0) and F(1) generations, while PTHrP expression was stronger in -Se+I, +Se-I and -Se-I rats in both F(0) and F(1) animals.

CONCLUSIONS

Combined selenium and iodine deficiency impaired the growth of bone and cartilage. The changes in the expression of ColX and PTHrP induced by combined selenium and iodine deficiency were compatible to measurements of ColX and PTHrP in Kashin-Beck osteoarthropathy.

[Organic gallium improves tretinoin-induced osteoporosis in rats]

OBJECTIVE

To investigate the effect of organic gallium and gallium chloride on bone metabolism and their therapeutic effect against tretinoin-induced osteoporosis in rats.

METHODS

Rat models of osteoporosis was established with intragastric administration of tretinoin at the daily dose of 85 mg/kg for 15 days and randomized into control, organic gallium and gallium chloride groups. After administration of the corresponding treatments (none for the control group) for 4 weeks, the changes of the indices for osteoporosis were evaluated through biochemical and pathological approaches.

RESULTS

Tretinoin induced obvious changes in bone structure and contents of bone calcium and other elements, causing also significantly increased tartrate-resistant acid phosphatase (TRAP) and alkaline phosphatase (AKP), which suggested the development of osteoporosis. Administration of organic gallium and gallium chloride treatments increased the bone density, bone cortex thickness and the percentage of bone trabecula, and Ga, Ca, P contents in the femur and teeth, but lowered the activity of TRAP and AKP, suggesting decreased bone conversion rate. Compared with gallium chloride, organic gallium required smaller dose with better safety to produce better therapeutic effect.

CONCLUSION

Organic gallium can be safe and effective for treatment of tretinoin-induced osteoporosis in rats.

[Serum hyaluronic acid, tumor necrosis factor -alpha, vascular endothelial growth factor, NO, and Se levels in adult patients with Kashin-Beck disease]

OBJECTIVE

To investigate the association of serum levels of hyaluronic acid (HA), tumor necrosis factor-alpha (TNF-alpha), vascular endothelial growth factor (VEGF), NO, and Se with the clinical manifestations in adult patients with Kashin-Beck disease (KBD).

METHODS

Total 216 adults were selected for KBD screening from the KBD-prevalent areas in Yongshou county and the non-KBD areas of Chang'an county, Xi'an city, ShaanXi Province. According to the National Diagnostic Criteria of Kashin-Beck Disease in China, the diagnoses of KBD was established in 25 adult patients (11 men and 14 women, average age of 47.88+/-11.16 years), and 20 healthy control subjects from the KBD areas (8 men and 12 women, average age of 47.85+/-12.05 years) and 20 from the non-KBD areas (8 men and 12 women, average age of 47.45+/-11.24 years) were also selected to serve as controls. There was no significant difference in the average age and gender distribution between the 3 groups. The serum levels of HA, TNF-alpha, VEGF, NO and Se were measured by enzyme-linked immunosorbent assay, nitrate reductase method and griphite furnace atomic absorption spectrometry.

RESULTS

Serum NO level was significantly higher in KBD group (41.7+/-21.89 micromol/L) than in the health controls from KBD areas (17.1+/-13.01 micromol/L) and non-KBD areas (17.58+/-11.48 micromol/l, F=13.11, df=2, P<0.001). Serum TNF-alpha level in KBD group (32.7+/-3.55 pg/ml) was significantly higher than that in the control subjects from the non-KBD areas (30.95+/-2.22 pg/ml, F=3.672, df=2, P=0.031), but similar with the control subjects from the KBD areas (32.7+/-3.55 pg/ml). Serum TNF-alpha and NO levels were identified as the indices that differed between adult KBD patients and the controls from both KBD and non-KBD areas by differential analysis (the function of differentiation was 0.062xNO+0.173xTNF -7.218).

CONCLUSION

Serum TNF-alpha and NO levels are significantly increased in adult KBD patients and are associated with the clinical manifestations of KBD.

[Comparison of apoptosis of articular chondrocytes in the pathogenesis of Kashin-beck disease and primary osteoarthritis]

OBJECTIVE

To investigate chondrocyte apoptosis and expression of Fas and inducible nitric oxide synthase (iNOS) in articular cartilage in the pathogenesis of Kashin-beck disease (KBD) and primary osteoarthritis (OA).

METHODS

The collected samples of articular cartilage were divided into three groups: normal control (15 cases), KBD adults (15 cases) and OA (15 cases). Chondrocyte apoptosis was detected by terminal deoxynucleotidyl transferase biotin-dUTP nick end labeling method, and Fas and iNOS in articular cartilage were stained by immunohistochemistry.

RESULTS

The positive percentages of chondrocyte apoptosis stained in articular cartilage of KBD and OA were significantly higher than that of the control (P < 0.01), and the positive percentage of chondrocytes apoptosis in the eroded areas of articular cartilage were significantly higher than in the non-eroded areas in articular cartilage of the same patient with KBD and OA (P < 0.05). There was no significant difference in positive percentage of chondrocytes apoptosis between KBD and OA. The positive percentages of Fas and iNOS in chondrocytes were significantly higher in KBD and OA than in control (P < 0.01). Significant differences in Fas and iNOS expression between the eroded areas and non-eroded areas were seen in articular cartilage of patients with KBD and OA (P < 0.05), but such difference did not exist between KBD and OA.

CONCLUSION

Cell apoptosis seems to be associated with the pathogenesis of both KBD and OA. Fas and iNOS might mediate chondrocyte apoptosis.

[Analysis of allele frequencies of 6 short tandem repeat loci on chromosome 12 in patients with Kashing-Beck disease]

OBJECTIVE

To analyze the allele frequencies of 6 STR loci (D12S358, D12S1675, D12S1663, D12S1697, D12S16725 and D12S1613) on chromosome 12 among KBD patients and residents in the KBD and non-KBD areas.

METHODS

EDTA-blood samples were collected from 146 unrelated Chinese Han individuals in Shaanxi Province including 57 KBD patients, 48 control subjects living in the Kashing-Beck disease(KBD) area and 48 in the non-KBD area. The DNA samples were extracted and amplified by PCR, and the PCR products were analyzed by ABI 3100 Genetic Analyzer.

RESULTS

In KBD patients, the allele number for the 6 STR loci (D12S358, D12S1675, D12S1663, D12S1697, D12S16725 and D12S1613) was 7, 7, 7, 10, 12 and 8, and the genotype number were 13, 12, 9, 17, 19 and 10, respectively; in the residents in KBD area, the allele number was 7, 5, 7, 9, 13 and 9, and the genotype number 12, 10, 12, 19, 16 and 8; in residents in non-KBD area, the allele number was 7, 5, 5, 12, 8 and 9, and the genotype number 17, 16, 8, 22, 14 and 8. There were significant differences in the allele frequencies in the D12S1725 loci between KBD patients and residents living in KBD area (P=0.0119) and the non-KBD area (P=0.0050), but no significant difference in other 5 loci among the 3 groups.

CONCLUSION

KBD patients have significantly different allele distribution patterns in the D12S1725 loci from the control subjects.

Chondrocyte apoptosis and expression of Bcl-2, Bax, Fas, and iNOS in articular cartilage in patients with Kashin-Beck disease

OBJECTIVE

Kashin-Beck disease (KBD) is a chronic, endemic osteochondropathy principally occurring in children. We investigated apoptotic chondrocyte death and the expression of Bcl-2, Bax, Fas, and inducible nitric oxide synthase (iNOS) in articular cartilage from patients with KBD in order to determine the pathogenesis of chondronecrosis in KBD.

METHODS

Samples of articular cartilage were divided into 2 groups: control children (15 samples from 15 cases), and children with KBD (15 samples from 15 cases). KBD patients were diagnosed according to "Pathological Criteria to Diagnose KBD in China." Chondrocyte apoptosis was detected by TUNEL staining, and Bcl-2, Bax, Fas, and iNOS-positive articular chondrocytes were stained by immunohistochemistry. Articular cartilage was classified in 3 zones, and positive findings were counted by light microscopy for cytoplasmic staining by polyclonal antibodies of Bcl-2, Bax, Fas, and iNOS and apoptotic chondrocytes by TUNEL.

RESULTS

The percentage of positive apoptotic chondrocytes stained by TUNEL in the middle zone of articular cartilage from the KBD patient group (33.60% +/- 2.71%) was higher than that of controls (1.33% +/- 0.41%; p < 0.01). The percentages of chondrocytes staining for Bcl-2, Bax, Fas, and iNOS in KBD patients were significantly higher than in controls (p < 0.01); the remarkable difference in Bcl-2, Bax, Fas, and iNOS expression among the upper, middle, and deep cartilage zones was also seen in KBD articular cartilage (p < 0.01); and staining for Bcl-2, Bax, Fas, and iNOS in KBD patients was prominent in the upper zone (41.93% +/- 12.26%, 45.60% +/- 15.78%, 53.60% +/- 16.49%, 45.47% +/- 14.02%, respectively) and the middle zone (14.93% +/- 3.50%, 13.87% +/- 4.32%, 23.27% +/- 4.83%, 21.67% +/- 6.82%) of articular cartilage.

CONCLUSION

The apoptotic chondrocytes and Bcl-2, Bax, Fas, and iNOS-positive chondrocytes were significantly more numerous in patients with KBD than in controls.

Abnormal expression of Col X, PTHrP, TGF-beta, bFGF, and VEGF in cartilage with Kashin-Beck disease

The purpose of the current study was to investigate the abnormal expression of Col X, PTHrP, TGF-beta, bFGF, and VEGF in cartilage from patients with Kashin-Beck disease (KBD) to understand the pathogenesis of chondronecrosis in KBD. Articular cartilage and growth plate cartilage collected were divided into four groups: control children (8 samples, 5 cases), KBD children (19 samples, 9 cases), control adults (8 samples, 6 cases), and KBD adults (16 samples, 15 cases). The presence of PTHrP, TGF-beta1, bFGF, VEGF, and collagen X in articular cartilage and in growth plate cartilage was analyzed by immunohistochemistry. Articular cartilage and growth plate were each divided in three zones, and the rate of positive cells was counted by light microscope for cytoplasmic and pericellular staining. Results showed that (1) in KBD children, Col X expression was lower in the deep zone of growth plate cartilage than in normal children; in articular cartilage of KBD adults, however, collagen X expression was higher in the middle zone compared to the controls; (2) staining for bFGF, PTHrP, TGF-beta1, and VEGF in KBD adult patients was prominent in the chondrocyte clusters and the eroded surface of articular cartilage, and the percentage of chondrocyte staining was significantly higher than in control samples (t = 3.64-10.34, df = 12 for children and 19 for adults, P = 0.002-0.0001); and (3) the enhanced PTHrP, TGF-beta1, and VEGF staining in the deep and middle zone of KBD articular cartilage correlated with the high incidence of chondronecrosis in the middle zone (48.5% +/- 10.2%) and deep zone (70.6% +/- 27.0%) of adult KBD cartilage. In conclusion, Col X expression was reduced in areas of chondrocyte necrosis in the deep zone of KBD articular cartilage, indicating changes in terminal chondrocyte differentiation. PTHrP, TGF-beta1, and VEGF expression was significantly altered and indicated degenerative changes in KBD cartilage, which initially resemble those occurring in osteoarthritis, but lead eventually to chondronecrosis, an event not observed in osteoarthritis.

[Analysis of genetic polymorphism of 7 STR loci on chromosome 12 in Shaanxi Han populations]

To analyze the genetic polymorphism of 7 STR loci (D12S1718,D12S1675, D12S358, D12S367, D12S1638, D12S1646 and D12S1682) on chromosome 12 in Shaanxi Hans. EDTA-blood specimens were collected from 80 unrelated individuals from Chinese Han population in Shaanxi province. The DNA samples were extracted and relevant fragments were amplified by polymerase chain reaction (PCR). The PCR products were analyzed by ABI 3100 Genetic Analyzer. The number of alleles and genotypes observed at loci D12S1718, D12S1675, D12S358, D12S367, D12S1638, D12S1646 and D12S1682 were 7, 10, 8, 8, 6, 9, 11 for alleles and 10, 17, 18, 18, 14, 18, and 26 for genotypes, respectively. The heterozygosities for the 7 STR loci were 44.28%, 66.10%, 78.89%, 77.89%, 73.69%, 74.55% and 82.39%, respectively. The distribution of allele frequencies of 7 STR loci on chromosome 12 was consistent with Hardy-Weinberg equilibrium and relatively high genetic polymorphism was observed in Shaanxi Han population.

Induction of Th1-type immunity and tumor protection with a prostate-specific antigen DNA vaccine

Prostate specific antigen (PSA) is a serum marker that is widely used in the detection and monitoring of prostate cancer. Though PSA is a self-antigen, T cell responses to PSA epitopes have been detected in healthy men and prostate cancer patients, suggesting it may be used as a target for active immunotherapy of prostate cancer. A PSA DNA vaccine (pPSA) was evaluated in mice and monkeys for its ability to induce antigen-specific immune responses. Mice immunized intradermally with pPSA demonstrated strong PSA-specific humoral and cellular immunity. The anti-PSA immune responses were skewed toward Th1, as shown by high IFNgamma and IL-2 production. The immune response was sufficient to protect mice from challenge with PSA-expressing tumor cells. Tumor protection was durable in the absence of additional vaccination, as demonstrated by protection of vaccinated mice from tumor rechallenge. Furthermore, pPSA vaccination induced PSA-specific antibody titers in male cynomolgus monkeys, which express a closely related PSA gene. These results demonstrate that vaccination with pPSA may be able to break tolerance and can induce an immune response that mediates tumor protection.

[Analysis on allele frequencies of 7 short tandem repeat loci of Kashing-Beck disease patients on]

OBJECTIVE

To analyze the allele frequencies of 7 short tandem repeat (STR) loci (D12S1718, D12S1675, D12S358, D12S367, D12S1638, D12S1646 and D12S1682) on chromosome 12 among Kashing-Beck disease (KBD) patients and the control population living in the KBD areas and non-KBD area.

METHODS

EDTA-blood specimens were collected from 102 unrelated individuals of Chinese Han population in Shaanxi province including 29 KBD patients,30 controls living in the KBD area and 43 living in the non-KBD area. DNA samples were extracted using the Wizard Genomic DNA purification kit (http://www. Promega. com) and were amplified by polymerase chain reaction (PCR) technique. The PCR products were analyzed by ABI 3100 Genetic Analyzer.

RESULTS

(1) In KBD patients group, the allele number for 7 STR loci were 4,7,7,8,5,5 and 7, the genotype number were 5,12,13,11,10,9 and 13; (2) In the control population living in KBD area, the allele number for 7 STR loci were 4,9,7,6,6,6 and 8,t he genotype number were 5,10,12,14,12,9 and 13;(3) In the control population living in the non-KBD area, the allele number for 7 STR loci were 7,9,7,7,5,8 and 11, the genotype number were 9,16, 17,16,12,15 and 20;(4) Compared with the allele frequencies among three groups, there were significant differences between KBD patients and the controls living in the KBD area (D12S367: P = 0.034; D12S1638: P = 0.041) and the controls living in the non-KBD area (D12S367: P = 0. 029; D12S1638: P= 0 .028) in the D12S367 and D12S1638 loci; (5) There were significant differences among KBD patients (P = 0.036), controls living in the KBD area (P = 0.039) and controls living in the non-KBD area in the D12S1646.

CONCLUSION

There was significant difference between KBD patients and the controls in the D12S367 and D12S1638 loci.

Validation of immunoassays used to assess immunogenicity to therapeutic monoclonal antibodies

Immunogenicity has always been an important consideration in the evaluation of pharmaceutical protein biologics. In this article, method validation parameters relevant to enzyme immunoassays are described for assays applied to the analysis of anti-drug antibodies, with special considerations for immunogenicity to therapeutic monoclonal antibodies. Common strategies for experimental investigation of various validation parameters are proposed. In addition, a novel, yet simple, approach is proposed to categorize the validation effort into two mutually interdependent phases, based on the characterization of validation parameters as "system descriptive" or "system controlled". System descriptive parameters are those that must be characterized but need not have pre-specified acceptance criteria for assay validation. In contrast, system-controlled parameters should be understood early in assay development, and optimized and confirmed using a priori acceptance criteria in validation to assure sufficient control over them during routine bioanalysis. This approach not only streamlines the validation process but also eliminates unnecessary redundancies. This validation method can be achieved with proper scientific rigor and remain within the realm of GLP compliance. The authors hope that other research groups would engage in discussions on validation of anti-drug antibody assays in order to establish a consistent approach across the industry and academia.

[Chondrocyte apoptosis and the expression of Bcl-2, Bax, Fas and iNos in articular cartilage in Kashin-Beck disease]

OBJECTIVE

To investigate the characteristics of chondrocyte apoptosis and distribution of Bcl-2, Bax, Fas and iNos expressions in articular cartilage in Kashin-Beck disease (KBD).

METHODS

Samples of articular cartilage were collected from 15 healthy children and 15 children with KBD diagnosed according to the Pathological Criteria of KBD Diagnosis in China. Chondrocyte apoptosis was detected by TUNEL method, and the articular chondrocytes positive for Bcl-2, Bax, Fas and iNos were stained by B-SA immunohistochemistry.

RESULTS

The percentage of apoptotic chondrocytes positively stained by TUNEL in the middle layer of articular cartilage was significantly higher in KBD children than in the control group (33.60%+/-2.71% vs 1.33%+/-0.41%, t=11.59, P<0.01). Significant difference in Bcl-2, Bax, Fas and iNos expressions was observed between the upper, middle and deep layers of the articular cartilage of KBD children (F =73.49-114.42, P<0.01), and staining for Bcl-2, Bax, Fas and iNos in KBD children was prominent in the upper layer (41.93%+/-12.26%, 45.60%+/-15.78%, 53.60%+/-16.49%, and 45.47%+/-14.02%, respectively) and the middle layer (14.93%+/-3.50%, 13.87%+/-4.32%, 23.27%+/-4.83%, and 21.67%+/-6.82%, respectively) of the articular cartilage; the percentages of chondrocytes positively stained for Bcl-2, Bax, Fas and iNos were significantly higher than those of the control group (t=11.75-18.65, P<0.01).

CONCLUSION

The percentages of apoptotic chondrocytes and chondrocytes positive for Bcl-2, Bax, Fas and iNos in the articular cartilage of children with KBD are significantly higher than those in healthy children.

[Clinic significance of nm23, collage IV and PCNA expression in non-small cell lung cancer]

BACKGROUND

To study the significance of nm23, collagen IV and PCNA expressions in non-small cell lung cancer.

METHODS

Expressions of the nm23, collagen IV and PCNA in 84 cases of non-small cell lung cancer were examined with SP immunohistochemical technique. Of the 84 cases, there were squamous cell carcinoma 42, adenocarcinoma 42, stage I 27, stage II 24, stage III 24, and stage IV 9. Statistical analysis was performed with Chi-Square test.

RESULTS

Expressions of the nm23, collagen IV and PCNA in 84 cases of non-small cell lung cancer were 60. 7% ( 51/ 84) , 75. 0% ( 63/ 84) and 53. 6% ( 45/ 84) respectively. There was negative correlation between the lymph node metastasis and the expressions of nm23 and collagen IV in squamous cell carcinoma, and the expressions of collagen IV and PCNA were associated with tumor differentiation. No correlation was found between TNM stage and expressions of nm23, collagen IV and PCNA.

CONCLUSIONS

The results indicate that nm23, collagen IV and PCNA participate the modulation of metastasis of non-small cell lung cancer and that they may be used to evaluate the potential of metastasis.

Blockade of CD28-B7, but not CD40-CD154, prevents costimulation of allogeneic porcine and xenogeneic human anti-porcine T cell responses

Despite increasing use of swine in transplantation research, the ability to block costimulation of allogeneic T cell responses has not been demonstrated in swine, and the effects of costimulatory blockade on xenogeneic human anti-porcine T cell responses are also not clear. We have compared the in vitro effects of anti-human CD154 mAb and human CTLA4IgG4 on allogeneic pig T cell responses and xenogeneic human anti-pig T cell responses. Both anti-CD154 mAb and CTLA4IgG4 cross-reacted on pig cells. While anti-CD154 mAb and CTLA4IgG4 both inhibited the primary allogeneic pig MLRs, CTLA4IgG4 (7.88 microg/ml) was considerably more inhibitory than anti-CD154 mAb (100 microg/ml) at optimal doses. Anti-CD154 mAb inhibited the production of IFN-gamma by 75%, but did not inhibit IL-10 production, while CTLA4IgG4 completely inhibited the production of both IFN-gamma and IL-10. In secondary allogeneic pig MLRs, CTLA4IgG4, but not anti-CD154 mAb, induced Ag-specific T cell anergy. CTLAIgG4 completely blocked the indirect pathway of allorecognition, while anti-CD154 mAb blocked the indirect response by approximately 50%. The generation of porcine CTLs was inhibited by CTLA4IgG4, but not by anti-CD154 mAb. Human anti-porcine xenogeneic MLRs were blocked by CTLA4IgG4, but only minimally by anti-CD154 mAb. Finally, CTLA4IgG4 prevented secondary xenogeneic human anti-porcine T cell responses. These data indicate that blockade of the B7-CD28 pathway was more effective than blockade of the CD40-CD154 pathway in inhibiting allogeneic pig T cell responses and xenogeneic human anti-pig T cell responses in vitro. These findings have implications for inhibiting cell-mediated immune responses in pig-to-human xenotransplantation.

[The reconstruction of laryngeal function in subtotal laryngectomy with preservation of arytenoid cartilage]

OBJECTIVE

To evaluate subtotal laryngectomy with preservation of arytenoid cartilage to reconstruct laryngeal function in T3 glottic or supraglottic laryngeal cancer.

METHODS

Subtotal laryngectomy with preservation of arytenoid cartilage to reconstruct laryngeal function was reviewed in 20 patients with T3 laryngeal cancer(3 cases with glottic cancer and 17 cases with supraglottic cancer). Recurrent laryngeal nerve was preserved during surgery. The mucous membranes between cricoid cartilage and pharynx were sewed up accordingly.

RESULTS

All patients had restored phonation and swallowing functions. The 3- and 5-year survival rates were 94.1% and 91.8% respectively. Decannulation rate was 95.0%.

CONCLUSION

Subtotal laryngectomy with preservation of arytenoid cartilage is recommended for T3 laryngeal cancer.

A 20-kDa domain is required for phosphatidic acid-induced allosteric activation of phospholipase D from Streptomyces chromofuscus

Two phospholipase D (PLD) enzymes with both hydrolase and transferase activities were isolated from Streptomyces chromofuscus. There were substantial differences in the kinetic properties of the two PLD enzymes towards monomeric, micellar, and vesicle substrates. The most striking difference was that the higher molecular weight enzyme (PLD57 approximately 57 kDa) could be activated allosterically with a low mole fraction of phosphatidic acid (PA) incorporated into a PC bilayer (Geng et al., J. Biol. Chem. 273 (1998) 12195-12202). PLD42/20, a tightly associated complex of two peptides, one of 42 kDa and the other 20 kDa, had a 4-6-fold higher Vmax toward PC substrates than PLD57 and was not activated by PA. N-Terminal sequencing of both enzymes indicated that both components of PLD42/20 were cleavage products of PLD57. The larger component included the N-terminal segment of PLD57 and contained the active site. The N-terminus of the smaller peptide corresponded to the C-terminal region of PLD57; this peptide had no PLD activity by itself. Increasing the pH of PLD42/20 to 8.9, followed by chromatography of PLD42/20 on a HiTrap Q column at pH 8.5 separated the 42- and 20-kDa proteins. The 42-kDa complex had about the same specific activity with or without the 20-kDa fragment. The lack of PA activation for the 42-kDa protein and for PLD42/20 indicates that an intact C-terminal region of PLD57 is necessary for activation by PA. Furthermore, the mechanism for transmission of the allosteric signal requires an intact PLD57.