Long-lasting Responses Research Articles

Mucosal administration of anti-bacterial antibodies provide long-term cross-protection against Pseudomonas aeruginosa respiratory infection

Bacterial respiratory infections, either acute or chronic, are major threats to human health. Direct mucosal administration, through the airways, of therapeutic antibodies (Abs) offers a tremendous opportunity to benefit patients with respiratory infections. The mode of action of anti-infective Abs relies on pathogen neutralization and crystallizable fragment (Fc)-mediated recruitment of immune effectors to facilitate their elimination. Using a mouse model of acute pneumonia induced by Pseudomonas aeruginosa, we depicted the immunomodulatory mode of action of a neutralizing anti-bacterial Abs. Beyond the rapid and efficient containment of the primary infection, the Abs delivered through the airways harnessed genuine innate and adaptive immune responses to provide long-term protection, preventing secondary bacterial infection. In vitro antigen-presenting cells stimulation assay, as well as in vivo bacterial challenges and serum transfer experiments indicate an essential contribution of immune complexes with the Abs and pathogen in the induction of the sustained and protective anti-bacterial humoral response. Interestingly, the long-lasting response protected partially against secondary infections with heterologous P. aeruginosa strains. Overall, our findings suggest that Abs delivered mucosally promotes bacteria neutralization and provides protection against secondary infection. This opens novel perspectives for the development of anti-infective Abs delivered to the lung mucosa, to treat respiratory infections.

Sustained antigens delivery using composite microneedles for effective epicutaneous immunotherapy.

Allergen-specific immunotherapy (SIT) is a desirable way of therapy for various allergic diseases such as food allergy (FA). However, frequent visits for more than 3 years and potential adverse effects often hinder patient compliance. Recently, many researchers started focusing on microneedles (MNs) as a new method for SIT. In this study, we proposed an implantable MNs system produced by a two-step casting process, consisting of OVA (antigen)-loaded silk microneedles and a dissolvable, flexible polyvinyl alcohol (PVA) pedestal. Different from PVA, silk fibroin hydrogel has preferable vaccine release ability in vivo and in vitro. Once MNs are inserted into the skin, the PVA pedestal can dissolve in the interstitial fluid of the excised skin within 5 min and implant the OVA-loaded silk microneedle tips in dermal layer as a sustained antigen depot, thus inducing long-lasting immune response for at least 2 weeks. After receiving 3 doses of MN-based immunotherapy, the immune response in OVA-sensitized mice was successfully suppressed, with no apparent side effects. Compared to conventional subcutaneous immunotherapy (total dose of 150 [Formula: see text]g), MN immunotherapy ameliorated systemic anaphylaxis more effectively even at a lower dose (total dose of 30 [Formula: see text]g), demonstrating the antigen dose-sparing potential of the proposed MNs. Moreover, due to the prolonged release effect of silk-PVA composite MNs, the frequency of immunotherapy can be significantly reduced. To sum up, through prolonged skin exposure to antigen, this implantable designed MN may offer a new therapeutic strategy for FA treatment with significant improvements in efficacy and convenience. Schematic illustration of silk-PVA composite microneedles, consisting of OVA (antigen)-loaded silk microneedles and a dissolvable, flexible PVA pedestal. Once inserted into the skin, the PVA pedestal can dissolve in the interstitial fluid of the excised skin within 5 min. Subsequently, the OVA-loaded silk microneedle tips were implanted in the dermal layer as a sustained antigen depot and induced long-lasting immune response. This MNs-based immunotherapy can significantly modulate the Th1/Th2 imbalance of sensitized mice.

A protective measles virus-derived vaccine inducing long-lasting immune responses against influenza A virus H7N9

A novel Influenza A virus (subtype H7N9) emerged in spring 2013 and caused considerable mortality in zoonotically infected patients. To be prepared for potential pandemics, broadly effective and safe vaccines are crucial. Recombinant measles virus (MeV) encoding antigens of foreign pathogens constitutes a promising vector platform to generate novel vaccines. To characterize the efficacy of H7N9 antigens in a prototypic vaccine platform technology, we generated MeVs encoding either neuraminidase (N9) or hemagglutinin (H7). Moraten vaccine strain-derived vaccine candidates were rescued; they replicated with efficiency comparable to that of the measles vaccine, robustly expressed H7 and N9, and were genetically stable over 10 passages. Immunization of MeV-susceptible mice triggered the production of antibodies against H7 and N9, including hemagglutination-inhibiting and neutralizing antibodies induced by MVvac2-H7(P) and neuraminidase-inhibiting antibodies by MVvac2-N9(P). Vaccinated mice also developed long-lasting H7- and N9-specific T cells. Both MVvac2-H7(P) and MVvac2-N9(P)-vaccinated mice were protected from lethal H7N9 challenge.

Computer-Aided Discovery of Potent Broad-Spectrum Vaccine Adjuvants.

Adjuvants stimulate the immune system to vigorously respond to a vaccine. While current adjuvants such as aluminum salts and oil-in-water emulsions have been used for decades, they do not generate broad and long-lasting responses in many vaccines. Consequently, more potent adjuvants are needed. Here, using computer-aided molecule design and machine learning, we discovered 2 new, broad-spectrum adjuvants that can boost vaccine responses. Our library containing 46 toll-like receptor (TLR)-targeting agonist ligands were assembled on Au nanoparticles. Comprehensive in vitro, ex vivo and in vivo studies showed both leads promoted dendritic cell activation via multiple TLRs and enhanced antigen presentation to T cells. When used together with tumor-specific antigens to immunize mice against B16-OVA melanoma and 4T1-PD1 breast cancer, both adjuvants unleashed strong immune responses that suppressed tumor growth and lung metastases. Our results show computer-aided design and screening can rapidly uncover potent adjuvants for tackling waning immunity in current vaccines.

Discontinuation of anti-PD1 in advanced melanoma: an observational retrospective study from the Italian Melanoma Intergroup

BackgroundImmunotherapy has improved the survival of patients with stage IV melanoma. In responders, clinical benefits may be long-lasting and persist even after treatment discontinuation. The optimal duration of anti-PD1 (anti-Programmed cell death-1) therapy in metastatic melanoma patients remains to be elucidated. Moreover, limited data are available on clinical outcomes of patients that discontinued anti-PD1 immunotherapy in a real-life setting. The aim of this study was to evaluate the progression-free survival (PFS) in patients with metastatic melanoma who interrupted anti-PD-1 treatment in the in the absence of disease progression. MethodsWe retrospectively reviewed patients with advanced/metastatic melanoma treated with anti-PD1 immunotherapy at 23 Italian Melanoma Intergroup (IMI) centres. The study investigated the risk of relapse in patients who stopped anti-PD1 therapy due to CR (Complete response), treatment-related toxicity, or by their own choice after a long period of treatment. Clinical and biological factors associated with or without recurrence were evaluated. ResultsThe study population included 237 patients. The median age of patients was 68.9 years (standard deviation: 13; range 33–95). The median time on treatment was 33 months (standard deviation: 18, 7; range 1–98). Among the 237 patients, 128 (54%) interrupted the anti-PD1 for CR, 74 patients (31.2%) for adverse events (37 patients in CR, 27 patients in partial response (PR), ten patients in stable disease (SD), and 35 patients (14.8%) by their own choice (12 patients in CR, 17 patients in PR, and 6 patients in SD). After a mean follow-up of 21 months (range 1–81), PFS after anti-PD1 discontinuation was 85.7%. Thirty-four patients (14.3%) developed disease progression after a median of 12 months (range 1–35): ten patients (29.4%) after discontinuation in CR, 17 patients (50%) after discontinuation for treatment-related toxicity (seven in CR, five in PR, five in SD), and seven (20.6%) after discontinuation due to the patient’s decision (two in CR, four in PR, one in SD). Only 7.8% of patients who interrupted in CR (10/128), along with 23% of patients who interrupted for limiting toxicity (17/74) and 20% of patients who interrupted by their own choice (7/35), developed recurrence. Regarding patients who discontinued therapy because of CR, we observed a negative association between recurrence and site of primary melanoma, especially mucosal sites (p = <0.05, HR (Hazard ratio) 15.57 IC (confidence interval) 95% 2.64–91.73). Moreover, M1b patients who achieved a CR showed a lower number of relapses (p = <0.05, HR 3.84 IC 95% 1.40–8.48). ConclusionsThis study shows in a real-life setting that, with anti-PD-1 therapy, long-lasting responses, can be maintained after anti-PD1 interruption. In 70.6% of cases, recurrences were observed among patients who did not obtain a CR at treatment discontinuation.

Novel intranasal vaccine targeting SARS-CoV-2 receptor binding domain to mucosal microfold cells and adjuvanted with TLR3 agonist Riboxxim™ elicits strong antibody and T-cell responses in mice

SARS-CoV-2 continues to circulate in the human population necessitating regular booster immunization for its long-term control. Ideally, vaccines should ideally not only protect against symptomatic disease, but also prevent transmission via asymptomatic shedding and cover existing and future variants of the virus. This may ultimately only be possible through induction of potent and long-lasting immune responses in the nasopharyngeal tract, the initial entry site of SARS-CoV-2. To this end, we have designed a vaccine based on recombinantly expressed receptor binding domain (RBD) of SARS-CoV-2, fused to the C-terminus of C. perfringens enterotoxin, which is known to target Claudin-4, a matrix molecule highly expressed on mucosal microfold (M) cells of the nasal and bronchial-associated lymphoid tissues. To further enhance immune responses, the vaccine was adjuvanted with a novel toll-like receptor 3/RIG-I agonist (Riboxxim™), consisting of synthetic short double stranded RNA. Intranasal prime-boost immunization of mice induced robust mucosal and systemic anti-SARS-CoV-2 neutralizing antibody responses against SARS-CoV-2 strains Wuhan-Hu-1, and several variants (B.1.351/beta, B.1.1.7/alpha, B.1.617.2/delta), as well as systemic T-cell responses. A combination vaccine with M-cell targeted recombinant HA1 from an H1N1 G4 influenza strain also induced mucosal and systemic antibodies against influenza. Taken together, the data show that development of an intranasal SARS-CoV-2 vaccine based on recombinant RBD adjuvanted with a TLR3 agonist is feasible, also as a combination vaccine against influenza.

Long-Lasting Therapeutic Response following Treatment with Pembrolizumab in Patients with Non-Small Cell Lung Cancer: A Real-World Experience

Immune checkpoint inhibitors (ICIs), pembrolizumab in particular, have been shown to be vastly more efficacious than traditional cytotoxic or platinum-based chemotherapies in the treatment of non-small cell lung cancer (NSCLC). While there are plenty of data showing their efficacy and safety profiles, very little exists about the long-term effects of pembrolizumab. We compiled all patients with NSCLC who were treated with pembrolizumab at our institution and had progression-free survival (PFS) of at least 2 years during or after the treatment period. Within this group, we examined the long-term rates of PFS and overall survival (OS), side effect profiles, treatment, and overall disease course up to 60 months after starting treatment. This study included 36 patients with median (range) follow up times from treatment initiation in months as follows: 36 (28-65) overall; 39.5 (28-65) for adenocarcinoma; and 36 (30-58) for squamous cell carcinoma. The median (range) of OS and PFS (months) was comparable for adenocarcinoma, 36 (23-55); and squamous cell carcinoma, 35.5 (28-65). Overall, pembrolizumab shows remarkable long-term safety and efficacy in NSCLC patients. In patients who show an initially strong response and can make it to 24 months of PFS, disease progression after this period seems increasingly unlikely.

Canakinumab leads to rapid reduction of neutrophilic inflammation and long-lasting response in Schnitzler syndrome.

Interleukin-1 (IL-1)-blocking therapies are effective in reducing disease severity and inflammation in Schnitzler syndrome. Here, we present a patient with Schnitzler syndrome treated successfully using canakinumab for over 10 years. Complete clinical response was associated with a decrease in dermal neutrophil number and expression of the pro-inflammatory cytokines IL-1β, IL-8, and IL-17 as assessed by immunohistochemical studies.

Identification of a Novel Keto Sugar Component in Streptococcus pneumoniae Serotype 12F Capsular Polysaccharide and Impact on Vaccine Immunogenicity.

Implementation of conjugate vaccine technology revolutionized the ability to effectively elicit long-lasting immune responses to bacterial capsular polysaccharides. Although expansion of conjugate vaccine serotype coverage is designed to target residual disease burden to pneumococcal serotypes not contained in earlier vaccine versions, details of polysaccharide Ag structure, heterogeneity, and epitope structure components contributing to vaccine-mediated immunity are not always clear. Analysis of Streptococcus pneumoniae serotype 12F polysaccharide by two-dimensional nuclear magnetic resonance spectroscopy and mass spectrometry revealed a partial substitution of N-acetyl-galactosamine by the keto sugar 2-acetamido-2,6-dideoxy-xylo-hexos-4-ulose (Sug) in up to 25% of the repeat units. This substitution was not described in previous published structures for 12F. Screening a series of contemporary 12F strains isolated from humans (n = 17) identified Sug incorporation at varying levels in all strains examined. Thus, partial Sug substitution in S. pneumoniae serotype 12F may have always been present but is now detectable by state-of-the-art analytical techniques. During the steps of conjugation, the serotype 12F Sug epitope is modified by reduction, and both polysaccharide PPSV23 and conjugate PCV20 vaccines contain 12F Ags with little to no Sug epitope. Both PCV20 and PPSV23 vaccines were evaluated for protection against circulating 12F strains with varying amounts of Sug in their repeat unit based on an opsonophagocytic killing assay involving HL-60 cells and rabbit complement. Both vaccines elicited human-derived neutralizing Abs against serotype 12F, independent of Sug level between ∼2 and 25 mol%. These findings suggest that the newly identified serotype 12F Sug epitope is likely not an essential epitope for vaccine-elicited protection.

Inulin acetate as a novel recombinant subunit vaccine carrier for immunization of tilapia against tilapia lake virus

Tilapia lake virus (TiLV) is highly contagious and pathogenic to tilapia, causing enormous economic losses in tilapia industry. Up to now, there is no commercial vaccine is available for against TiLV infection. Therefore, a novel vaccine with high immune efficacy is urgently-needed. In this study, we examined the efficacy of subunit vaccine against TiLV through intramuscular injection using inulin acetate (InAc) nanoparticles encapsulation. The S2 protein (encoded by segment 2 gene of TiLV) was used as the antigen and the delivery system was named as InAc-S2. The toxicity analysis showed InAc-S2 had no significant influence on fishes growing and development. Meanwhile, we found InAc-S2 has a dual-release pattern (initial burst release and sustained release) in antigen release. Subsequently, tilapia was injected intramuscularly by different treatments (PBS, InAc, S2, and InAc-S2), and the immune protective effect induced by these treatments was analyzed. We found a powerful and long-lasting humoral or cellular immune response (serum antibody production, immune-related parameters and immune-related genes expression) can be induced in fishes by injected with InAc-S2 in comparison with those injected with S2 antigen alone. Moreover, a relative higher survival rate was observed in fish vaccinated with InAc-S2 at the dose of 4 μg protein/g of fish (with the relative percentage survival of 58.6%). Overall, this study for the first time demonstrated the potential of InAc as subunit vaccine carrier against TiLV infection and provide a reference to novel vaccine development in aquaculture.

Two Cases of TMEM151A-Associated Paroxysmal Dyskinesia in a Single-Center Series of PRRT2-Negative Patients.

Two Cases of TMEM151A-Associated Paroxysmal Dyskinesia in a Single-Center Series of PRRT2-Negative Patients.

Heterologous vaccination with subunit protein vaccine induces a superior neutralizing capacity against BA.4/5-included SARS-CoV-2 variants than homologous vaccination of mRNA vaccine.

BA.4 and BA.5 (BA.4/5), the subvariants of Omicron, are more transmissible than BA.1 with more robust immune evasion capability because of its unique spike protein mutations. In light of such situation, the vaccination against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is in desperate need of the third booster. It has been reported that heterologous boosters might produce more effective immunity against wild-type SARS-CoV-2 and the variants. Additionally, the third heterologous protein subunit booster should be considered potentially. In the present study, we prepared a Delta full-length spike protein sequence-based mRNA vaccine as the "priming" shot and developed a recombinant trimeric receptor-binding domain (RBD) protein vaccine referred to as RBD-HR/trimer as a third heterologous booster. Compared to the homologous mRNA group, the heterologous group (RBD-HR/trimer vaccine primed with two mRNA vaccines) induced higher neutralizing antibody titers against BA.4/5-included SARS-CoV-2 variants. In addition, heterologous vaccination exhibited stronger cellular immune response and long-lasting memory response than the homologous mRNA vaccine. In conclusion, a third heterologous boosting with RBD-HR/trimer following two-dose mRNA priming vaccination should be a superior strategy than a third homologous mRNA vaccine. The RBD-HR/trimer vaccine becomes an appropriate candidate for a booster immune injection.

A Shigella flexneri 2a synthetic glycan-based vaccine induces a long-lasting immune response in adults

Shigella is a leading cause of moderate to severe diarrhea worldwide and of diarrhea-associated deaths in children under 5 years of age in low-and middle-income countries. A vaccine against shigellosis is in high demand. SF2a-TT15, a synthetic carbohydrate-based conjugate vaccine candidate against Shigella flexneri 2a (SF2a) was found safe and strongly immunogenic in adult volunteers. Here, SF2a-TT15 at 10 µg oligosaccharide (OS) vaccine dose is shown to induce a sustained immune response in magnitude and functionality in the majority of volunteers followed up 2 and 3 years post-vaccination. High levels of either one of the humoral parameters as well as the number of specific-IgG memory B-cells determined 3 months after vaccination were good predictors of the durability of the immune response. This study is the first to examine the long-term durability of antibody functionality and memory B-cell response induced by a Shigella vaccine candidate.

Neoantigen-targeted CD8+ T cell responses with PD-1 blockade therapy.

Neoantigens are peptides derived from non-synonymous mutations presented by human leukocyte antigens (HLAs), which are recognized by antitumour T cells1-14. The large HLA allele diversity and limiting clinical samples have restricted the study of the landscape of neoantigen-targeted T cell responses in patients over their treatment course. Here we applied recently developed technologies15-17 to capture neoantigen-specific T cells from blood and tumours from patients with metastatic melanoma with or without response to anti-programmed death receptor1 (PD-1) immunotherapy. We generated personalized libraries of neoantigen-HLA capture reagents to single-cell isolate the T cells and clone their T cell receptors (neoTCRs). Multiple T cells with different neoTCR sequences (T cell clonotypes) recognized a limited number of mutations in samples from seven patients with long-lasting clinical responses. These neoTCR clonotypes were recurrently detected over time in the blood and tumour. Samples from four patients with no response to anti-PD-1 also demonstrated neoantigen-specific T cell responses in the blood and tumour to a restricted number of mutations with lower TCR polyclonality and were not recurrently detected in sequential samples. Reconstitution of the neoTCRs in donor T cells using non-viral CRISPR-Cas9 gene editing demonstrated specific recognition and cytotoxicity to patient-matched melanoma cell lines. Thus, effective anti-PD-1 immunotherapy is associated with the presence of polyclonal CD8+ T cells in the tumour and blood specific for a limited number of immunodominant mutations, which are recurrently recognized over time.

VLPs containing stalk domain and ectodomain of matrix protein 2 of influenza induce protection in mice

BackgroundAs a result of antigenic drift, current influenza vaccines provide limited protection against circulating influenza viruses, and vaccines with broad cross protection are urgently needed. Hemagglutinin stalk domain and ectodomain of matrix protein 2 are highly conserved among influenza viruses and have great potential for use as a universal vaccine.MethodsIn this study, we co-expressed the stalk domain and M2e on the surface of cell membranes and generated chimeric and standard virus-like particles of influenza to improve antigen immunogenicity. We subsequently immunized BALB/c mice through intranasal and intramuscular routes.ResultsData obtained demonstrated that vaccination with VLPs elicited high levels of serum-specific IgG (approximately 30-fold higher than that obtained with soluble protein), induced increased ADCC activity to the influenza virus, and enhanced T cell as well as mucosal immune responses. Furthermore, mice immunized by VLP had elevated level of mucosal HA and 4M2e specific IgA titers and cytokine production as compared to mice immunized with soluble protein. Additionally, the VLP-immunized group exhibited long-lasting humoral antibody responses and effectively reduced lung viral titers after the challenge. Compared to the 4M2e-VLP and mHA-VLP groups, the chimeric VLP group experienced cross-protection against the lethal challenge with homologous and heterologous viruses. The stalk domain specific antibody conferred better protection than the 4M2e specific antibody.ConclusionOur findings demonstrated that the chimeric VLPs anchored with the stalk domain and M2e showed efficacy in reducing viral loads after the influenza virus challenge in the mice model. This antibody can be used in humans to broadly protect against a variety of influenza virus subtypes. The chimeric VLPs represent a novel approach to increase antigen immunogenicity and are promising candidates for a universal influenza vaccine.

A Thermal-Stable Protein Nanoparticle That Stimulates Long Lasting Humoral Immune Response.

A thermally stable vaccine platform is considered the missing piece of vaccine technology. In this article, we reported the creation of a novel protein nanoparticle and assessed its ability to withstand extended high temperature incubation while stimulating a long-lasting humoral immune response. This protein nanoparticle was assembled from a fusion protein composed of an amphipathic helical peptide derived from the M2 protein of the H5N1 influenza virus (AH3) and a superfolder green fluorescent protein (sfGFP). Its proposed structure was modeled according to transmission electronic microscope (TEM) images of protein nanoparticles. From this proposed protein model, we created a mutant with two gain-of-function mutations that work synergistically on particle stability. A protein nanoparticle assembled from this gain-of-function mutant is able to remove a hydrophobic patch from its surface. This gain-of-function mutant also contributes to the higher thermostability of protein nanoparticles and stimulates a long lasting humoral immune response after a single immunization. This assembled nanoparticle showed increasing particle stability at higher temperatures and salt concentrations. This novel protein nanoparticle may serve as a thermally-stable platform for vaccine development.

Pomalidomide combinations are a safe and effective option after daratumumab failure

PurposeOutcomes of multiple myeloma (MM) patients who are refractory to daratumumab are dismal and no standard of treatment exists for this patients’ population. Here, we investigate the role of pomalidomide combinations in daratumumab-refractory MM patients.MethodsWe performed a retrospective analysis of myeloma patients treated at four referral centers (three in Germany and one in Italy). Review chart identified 30 patients with relapsed and refractory myeloma, who progressed during treatment with daratumumab and were treated with pomalidomide-based combinations in the subsequent lines of therapy.ResultsResponses improved from 37% with daratumumab to 53% with pomalidomide. Of seven patients with extramedullary MM (EMM), four achieved a clinical stabilization with pomalidomide, including one patient with a long-lasting complete response. Median progression-free survival and overall survival were 6 and 12 months, respectively. Pomalidomide combinations were well tolerated, no patient discontinued treatment due to adverse events.ConclusionThese data show that pomalidomide-based combinations can be an effective and safe salvage regimen for daratumumab-refractory patients, including those with EMM.

Mechanisms of response and resistance to combined decitabine and ipilimumab for advanced myeloid disease

AbstractThe challenge of eradicating leukemia in patients with acute myelogenous leukemia (AML) after initial cytoreduction has motivated modern efforts to combine synergistic active modalities including immunotherapy. Recently, the ETCTN/CTEP 10026 study tested the combination of the DNA methyltransferase inhibitor decitabine together with the immune checkpoint inhibitor ipilimumab for AML/myelodysplastic syndrome (MDS) either after allogeneic hematopoietic stem cell transplantation (HSCT) or in the HSCT-naïve setting. Integrative transcriptome-based analysis of 304 961 individual marrow-infiltrating cells for 18 of 48 subjects treated on study revealed the strong association of response with a high baseline ratio of T to AML cells. Clinical responses were predominantly driven by decitabine-induced cytoreduction. Evidence of immune activation was only apparent after ipilimumab exposure, which altered CD4+ T-cell gene expression, in line with ongoing T-cell differentiation and increased frequency of marrow-infiltrating regulatory T cells. For post-HSCT samples, relapse could be attributed to insufficient clearing of malignant clones in progenitor cell populations. In contrast to AML/MDS bone marrow, the transcriptomes of leukemia cutis samples from patients with durable remission after ipilimumab monotherapy showed evidence of increased infiltration with antigen-experienced resident memory T cells and higher expression of CTLA-4 and FOXP3. Altogether, activity of combined decitabine and ipilimumab is impacted by cellular expression states within the microenvironmental niche of leukemic cells. The inadequate elimination of leukemic progenitors mandates urgent development of novel approaches for targeting these cell populations to generate long-lasting responses. This trial was registered at www.clinicaltrials.gov as #NCT02890329.

Biomarker response to high-specific-activity I-131 meta-iodobenzylguanidine in pheochromocytoma/paraganglioma.

The objective of this study is to present the complete biomarker response dataset from a pivotal trial evaluating the efficacy and safety of high-specific-activity I-131 meta-iodobenzylguanidine in patients with advanced pheochromocytoma or paraganglioma. Biomarker status was assessed and post-treatment responses were analyzed for catecholamines, metanephrines, and serum chromogranin A. Complete biomarker response (normalization) or partial response, defined as at least 50% reduction from baseline if above the normal range, was evaluated at specified time points over a 12-month period. These results were correlated with two other study objectives: blood pressure control and objective tumor response as per RECIST 1.0. In this open-label, single-arm study, 68 patients received at least one therapeutic dose (~18.5 GBq (~500 mCi)) of high-specific-activity I-131 meta-iodobenzylguanidine. Of the patients, 79% and 72% had tumors associated with elevated total plasma free metanephrines and serum chromogranin A levels, respectively. Best overall biomarker responses (complete or partial response) for total plasma free metanephrines and chromogranin A were observed in 69% (37/54) and 80% (39/49) of patients, respectively. The best response for individual biomarkers was observed 6-12 months following the first administration of high-specific-activity I-131 meta-iodobenzylguanidine. Biochemical tumor marker response was significantly associated with both reduction in antihypertensive medication use (correlation coefficient 0.35; P = 0.006) as well as objective tumor response (correlation coefficient 0.36; P = 0.007). Treatment with high-specific-activity I-131 meta-iodobenzylguanidine resulted in long-lasting biomarker responses in patients with advanced pheochromocytoma or paraganglioma that correlated with blood pressure control and objective response rate. ClinicalTrials.gov number: NCT00874614.

P474 Postoperative disease course after appendectomy as experimental treatment for patients with therapy refractory moderate to severe ulcerative colitis

Abstract Background Increasing evidence suggests appendectomy as a potential experimental therapy for ulcerative colitis (UC). A prospective cohort study of laparoscopic appendectomy for treatment of therapy refractory UC showed a clinical response in nearly half of the patients with a substantial proportion of patients in endoscopic remission, after a postoperative follow-up of 3.7 years1. The current study aimed to explore disease course during long-term follow-up in patients undergoing appendectomy for therapy-refractory UC. Methods In this monocenter cohort series, all patients with therapy refractory UC referred for (procto)colectomy between 2012-2015 were counselled to undergo laparoscopic appendectomy instead. The primary endpoint was long-term clinical (≥3 points decrease in partial mayo score) and endoscopic response (Endoscopic Mayo score ≤1) displayed in individual time lines. Secondary endpoints included duration and loss of clinical and endoscopic response, de-escalation of medication, and failure (medical treatment switch or colectomy). Results A total of 25 patients (12 men; median age 41.0 years) underwent appendectomy. The median postoperative follow-up time was 7.5 [IQR 6.4-8.6] years. Clinical response was observed in 60% (15/25) after a median follow-up of 4.0 [IQR 3.0-7.0] months, and was 32% (8/25) at the end of follow-up. Endoscopic response was observed in 48% (12/25) after a median follow-up of 17.5 [IQR 3.3-38.8] months and was 24% (6/25) at the end of follow-up. The median duration of clinical and endoscopic response was 80.0 [20.0-93.0] an 45.5 [21.8-56.8] months, respectively. Six (24%) patients de-escalated medication during follow-up, five of which without subsequent failure. Seventeen (68%) patients failed during postoperative follow-up after appendectomy, of which nine patients (36%) required colectomy a median of 5.0 [IQR 2.0-13.5] months after appendectomy. Figure 1. Disease course after appendectomy per patient. Conclusion During the postoperative course following appendectomy for refractory UC, approximately half of the patients demonstrated long-lasting endoscopic response, more than half demonstrated long-lasting clinical response, and one third underwent colectomy. 1Stellingwerf ME, Sahami S, Winter DC, Martin ST, D'Haens GR, Cullen G, Doherty GA, Mulcahy H, Bemelman WA, Buskens CJ. Prospective cohort study of appendicectomy for treatment of therapy-refractory ulcerative colitis. Br J Surg. 2019 Nov;106(12):1697-1704.