Dose reduction of biologics in patients with plaque psoriasis: a review.

Dose reduction (DR) of first-generation biologics for plaque psoriasis (TNF-alpha inhibitors (i) and interleukin (IL)-12/23i) has been described in a previous scoping review. The literature on the DR of the newest generation of biologics (IL-17/23i) was scarce. The current review provides a literature update on the previous scoping review on the DR of all biologics, including the newest generation, with a focus on the uptake and implementation of DR in practice. The current literature search on DR revealed 14 new articles in addition to those in the previous review. Four of the newly found articles tested DR strategies, mostly focusing on first-generation biologics; only guselkumab (IL-23i) was included in one study. The other 10 studies showed data on regaining response after failure of DR, safety, cost-effectiveness, and uptake and implementation, as well as information about IL-17/23i. The eligibility criteria to start DR included both absolute and relative Psoriasis Area and Severity Index (PASI) scores (PASI ≤3/≤5/PASI 75-100) and/or Dermatology Life Quality Index (DLQI) ≤3/≤5, or BSA ≤1/≤2, or Physician Global Assessment (PGA) ≤1/0-2 during a period ranging from 12 weeks to ≥1 year. Most studies used PASI ≤5 and/or DLQI ≤5 or PGA ≤1 for ≥6 months. DR strategies were mostly performed by stepwise interval prolongation in two steps (to 67% of the standard dose, followed by 50%). Some studies of IL-17/23i reduced the dose to ±25%. The tested DR strategies on stepwise or fixed DR on TNF-αi and IL-12/23i (three studies), as well as one "on-demand" dosing study on IL-23i guselkumab, were successful. In the case of relapse of DR on TNF-αi and IL-12/23i, clinical effectiveness was regained by retreatment with the standard dose. All studies showed substantial cost savings with the biologic DR of TNF-αi and IL-12/23i. The identified barriers against the implementation of DR were mainly a lack of guidelines and scientific evidence on effectiveness and safety, and a lack of time and (technical) support. The identified facilitators were mainly clear guidelines, feasible protocols, adequate education of patients and physicians, and cost reduction. In conclusion, DR seems promising, but a research gap still exists in randomized, prospective studies testing DR strategies, especially of IL-17/23i, hampering the completion of guidelines on DR. Taking into account the identified barriers and facilitators most likely results in a more successful implementation of biologic DR in practice.

Attitudes and behaviour regarding dose reduction of biologics for psoriasis: a survey among dermatologists worldwide.

Dose reduction (DR) of biologics, where possible, seems promising for more efficient use of expensive biologics. For implementation of DR strategies, it is essential to get insight in factors that influence implementation. The objective of this study was to evaluate the attitudes and behaviour regarding dose reduction of biologic therapies for psoriasis among psoriasis expert dermatologists worldwide. A 27-question e-survey was sent through the International Psoriasis Council (IPC) to its 114 dermatologist councilors worldwide. The survey assessed demographics, general and DR prescription behaviour, and motivations for and barriers against application of DR. Of 57 respondents, 53 respondents who prescribed biologics were included for analysis. Thirty-seven (69.8%) applied DR (i.e., 'DR dermatologists'), and 16 (30.2%) did not (i.e., 'Non-DR dermatologists'). DR strategies varied among respondents. Regarding criteria for starting DR, differences were reported in required treatment duration, and interpretation and duration of stable low disease activity. In addition, the prolongation of intervals between injections varied between respondents. For most 'DR dermatologists' (n = 32/37, 86.5%), cost savings were one of the main reasons to apply DR. Fifteen out of 16 'Non-DR dermatologists' (94%) did not apply DR due to lack of scientific evidence. In conclusion, DR of biologics for psoriasis is part of clinical practice in psoriasis experts globally. Barriers for applying DR included lack of evidence or guidelines, and uncertainty on DR effects and risks. Although growing evidence shows DR feasibility, future studies are needed to accumulate and broaden evidence, along with development of (inter)national guidelines on DR strategies.

Dose Tapering of Biologics in Patients with Psoriasis: A Scoping Review.

INTRODUCTION: Biologics serve as a cornerstone in psoriasis treatment, with low disease activity or sometimes even clinical remission as a realistic treatment outcome. So far, it is unclear whether biologics should be tapered when this target is achieved. Dose tapering could offer potential benefits by decreasing side effects, the burden of repetitive injections and costs of biological therapy. However, clinical guidelines on dose tapering of biologicals in psoriasis patients are lacking. This scoping review was conducted to provide an overview of the current literature on dose tapering and offer guidance for clinicians in daily clinical practice. METHODS: Dose tapering is defined as the administration of a lower dose per administration, or the prolongation of the regular dose interval, after initial treatment according to the standard dosing. Four electronic databases (PubMed, EMBASE, Cochrane, and Web of Science) were systematically searched for literature on tapering of biologics in adult patients with psoriasis from 1 January 2000. RESULTS: We included 19 original articles on biologic tapering in psoriasis patients: four randomized controlled trials and 15 observational studies. Tapering eligibility criteria, tapering strategies, tapering outcomes, and recapture of response after relapse were assessed. Furthermore, the available evidence on possible predictors for successful tapering, and the effect of tapering on safety, quality of life and costs is summarized. The definition of low disease activity as a measure for tapering eligibility varied widely. Beside tapering criteria, tapering strategies were also heterogeneous. Of note, quality-of-life measurements were barely integrated in the evaluation of tapering outcomes. Literature on regaining response after relapse due to tapering was limited, but restored remission has been described. The included studies did not proclaim a significant effect of tapering on the occurrence of (severe) adverse events. Even though cost savings have been reported, no proper cost-effectiveness analysis has been conducted yet. CONCLUSION: Biologic tapering seems to be effective and safe in psoriasis patients with stable low disease activity or clinical remission. Available data on biologic dose tapering in patients with psoriasis are promising, but more research is warranted to fill the current gaps in knowledge.

Biologics are effective in treating psoriasis amongst other diseases, such as rheumatoid arthritis and Crohn's disease. However, biologics are costly, and can cause side effects, such as an increased risk of infection. In patients with rheumatoid arthritis, it is not uncommon to lower the dose of these biologics (also called "dose tapering"), once stable low disease activity, or even remission, is reached. However, in psoriasis patients, dose tapering of biologics is not common practice. In this "scoping review," we provide an overview of the available literature on dose tapering of biologics in adult patients with plaque psoriasis in order to address the current gaps in literature. We found 19 studies that addressed dose tapering. These studies used different criteria to determine which patients were eligible for tapering, which led to various interpretations of tapering success. This made it difficult for us to draw general conclusions on which tapering criteria and strategies should be further investigated. Dose tapering seems to be effective and safe in patients with a stable low disease activity, although more (high-quality) research is needed. Future studies should focus on generating more data on long-term safety, finding predictors for successful tapering, calculating the cost-effectiveness of dose tapering, and evaluating dose tapering in the newest generation of biologics.

Human IgM monoclonal antibody 16.88: pharmacokinetics and immunogenicity in colorectal cancer patients.

Twenty colorectal cancer patients were given an intravenous injection of human IgM monoclonal antibody (MAb) 16.88 (8 mg) conjugated to 131I for tumor localization. After a 2-week interval, a second injection with 200, 500, or 1000 mg of unlabeled antibody added was given to groups of five patients each. at the end of the 2-hour infusion, 66% of the radioactivity remained in the circulation. Blood clearance of the 131I-labeled MAb 16.88 was biphasic with a mean half-life (T1/2 alpha) of 12 hours and T1/2 beta of 45 hours. Clearance rate was 0.09 L/hour. More than 90% of the 131I in serum was protein bound, with an immunoreactive fraction of 80% in the first 48 hours. Size exclusion chromatography indicated no degradation products other than 131I in serum and urine. The urinary excretion rate of 131I increased to 1.5% of the dose per hour at 24 hours, with 50% of the dose excreted in 34 hours. The pharmacokinetic profile of 131I-labeled MAb 16.88 was neither influenced by the total protein dose of antibody administered nor affected by specific uptake in tumor tissue in individual patients, as determined on early immunoscintigrams. The larger antibody doses showed a slightly slower excretion of 131I. The assays applied to determine immunogenicity were enzyme-linked immunosorbent assay, radioimmunoassay, and the dot-blot assay. They had sensitivities ranging from 5 ng/mL to 0.5 micrograms/mL for goat or rabbit antihuman IgM. The assays did not reveal antihuman antibody responses.

A new application for liposomes in cancer therapy. Immunoliposomes bearing enzymes (immuno-enzymosomes) for site-specific activation of prodrugs.

We have tested a new type of immunoliposomes which may effectively mediate the targeting of enzymes to be used for site-specific prodrug activation (immuno-enzymosomes). The enzyme beta-glucuronidase, capable of activating the prodrug epirubicin-glucuronide (epi-glu), was coupled to the external surface of immunoliposomes directed towards ovarian cancer cells. A significant increase in cytotoxicity of the prodrug epi-glu was shown when the in vitro cultured cancer cells were pretreated with these immuno-enzymosomes.

A monoclonal antibody against human beta-glucuronidase for application in antibody-directed enzyme prodrug therapy.

The selectivity of anticancer agents may be improved by antibody-directed enzyme prodrug therapy (ADEPT). The immunogenicity of antibody-enzyme conjugates and the low tumor to normal tissue ratio calls for the use of a human enzyme and the development of a monoclonal antibody (MAb) against that enzyme for rapid clearance of the conjugate from the circulation. We isolated beta-glucuronidase from human liver. BALB/c mice were immunized with the roughly purified human liver beta-glucuronidase and we obtained an MAb designated 105. Immunoblotting showed reactivity with native tetrameric human beta-glucuronidase. MAb 105 neither bound to enzyme from bovine liver, rat liver, or mouse liver nor reacted with other human lysosomal enzymes. The antibody appeared to be useful to further purify human beta-glucuronidase from human liver or human placenta to homogeneity by affinity chromatography. MAb 105 did not inhibit the activity of human beta-glucuronidase. When human beta-glucuronidase was injected i.v. into BALB/c mice, the newly generated MAb 105 could indeed accelerate the clearance of the enzyme with a 50% drop in its activity within 5 min.

Comparison of two anthracycline-based prodrugs for activation by a monoclonal antibody-beta-glucuronidase conjugate in the specific treatment of cancer.

Antibody-directed enzyme prodrug therapy (ADEPT) may improve the therapeutic index of cytostatic agents. We compared two prodrugs, epirubicin-glucuronide (Epi-glu) and doxorubicin-spacer-glucuronide (Dox-sp-glu), for their cytotoxicity on activation by a monoclonal antibody-enzyme conjugate bound to tumor cells. The results showed that the prodrugs were 10 (Dox-sp-glu) and 100 (Epi-glu) times less toxic than the parent drugs against OVCAR-3 cells. This difference was a result of the hydrophilic property of the prodrugs resulting in a reduced cellular uptake. The enzyme-catalyzed hydrolysis of Dox-sp-glu by E. coli-derived beta-glucuronidase (GUS) (Km 500 microM, Vmax 21,000 mumol/min/g) was much more efficient than that of Epi-glu (Km 10 microM, Vmax 40 mumol/min/g). Incubation of OVCAR-3 cells with an enzyme-immunoconjugate prepared from monoclonal antibody 323/A3 and E. coli-derived GUS before treatment with prodrugs completely restored the cytotoxicity of the prodrugs to the level of the parent drugs.

Analysis of a conjugate between anti-carcinoembryonic antigen monoclonal antibody and alkaline phosphatase for specific activation of the prodrug etoposide phosphate.

The selective targeting of tumors by enzymes conjugated to monoclonal antibodies (mAb) may be an ideal approach to convert relatively nontoxic prodrugs into active agents at the tumour site. We used the anti-carcinoembryonic antigen mAb BW431/26 conjugated to alkaline phosphatase (AP) and phosphorylated etoposide (etoposide-P) as a prodrug to study the feasibility of this concept. Etoposide was phosphorylated with POCl3. Quantitative hydrolysis of etoposide-P to etoposide occurred within 10 min in the presence of AP. BW431/26 and AP were conjugated using a thioether bond. The AP conjugate retained 93% of its calculated activity. 125I-labelled AP conjugate did not show a reduction of immunoreactivity as determined by a cell-binding assay. SW1398 colon cancer cells were used to analyse the cytotoxicity of etoposide and etoposide-P. Etoposide (IC50 22 microM) was 100 times more toxic than etoposide-P (20% growth inhibition at 200 microM). Pretreatment of the cells with BW431/26-AP prior to etoposide-P exposure resulted in a dramatic increase in cytotoxicity (IC50 70 microM). The pharmacokinetics and tumour-localizing properties of BW431/27 and the AP conjugate were assessed in nude mice bearing SW1398 tumours. BW431/26 showed excellent tumour localization (10% of the injected dose/g tissue retained from 8 h to 120 h), whereas the AP conjugate showed a reduced tumour uptake (3%-0.3% of the injected dose/g tissue at 8-120 h), a faster clearance from the circulation and a high liver uptake. Radiolabelled AP showed a similar pharmacokinetic profile to the AP conjugate. Gel filtration analysis of blood, liver, and tumour samples indicated good stability of the conjugate.

Human IgM monoclonal antibody 16.88: pharmacokinetics and distribution in mouse and man.

Human IgM monoclonal antibody (MAb) 16.88 recognizes an antigen strongly expressed by colon cancer tissue. We used 131I-labelled 16.88 for biodistribution and pharmacokinetic studies in nude mice bearing WiDr or NIH:OVCAR-3 xenografts. Serum half-life was 8 h. Maximum tumour uptake was between 1 and 8 h after administration and amounted to, respectively, 3% and 1% of the injected dose g-1 for WiDr and NIH:OVCAR-3 tumours. Half-lives in these tumours were approximately 24 h. Tumour to normal colon uptake ratios increased from 2.3 at 24 h to 17 at 5 days after injection. Simultaneously, pharmacokinetic studies were performed in patients with advanced colon cancer reactive with 16.88. They were injected with 5 mCi 131I-16.88 by intravenous infusion over 2 h. Serum half-life was 20 h with greater than 90% of the 131I bound to 16.88. Within 40 h 50% of the injected dose was excreted as free 131I in the urine. In one patient an accelerated clearance was found, possibly caused by pre-existing antibodies reacting with 16.88. None of the patients showed an immune response against 16.88 antibody. Immunoscintigraphy showed positive tumour localization in the majority of the patients, best visualized at later days. We conclude that 16.88 has tumour localization properties while its human origin accounts for the lack of immunogenicity.

A monoclonal antibody-beta-glucuronidase conjugate as activator of the prodrug epirubicin-glucuronide for specific treatment of cancer.

The anti-pan carcinoma monoclonal antibody (MAb) 323/A3, linked to E. coli-derived beta-glucuronidase (GUS) was used to study the tumour-site-selective activation of the prodrug Epirubicin-glucuronide (Epi-glu). Epi-glu was isolated from the urine of patients treated with Epirubicin (Epi) by reversed phase chromatography on a silica-C18 column. Epi-glu was stable in human blood and was not converted into Epi by A2780, MCF-7, or OVCAR-3 cancer cells, despite the presence of intracellular GUS. The stability of the prodrug was confirmed in BALB/c mice. MAb 323/A3 and GUS were linked through a stable thioether bond. The conjugate (1:1) was purified by ion exchange and gel filtration chromatography. Binding to target cells revealed an immunoreactivity of at least 60% and good retention of enzyme activity. A protein dye (sulforhodamine B) assay was used to analyse cytotoxicity. Epi (IC50 of 0.003-0.2 microM) was 100-1,000 times more toxic than Epi-glu (IC50 of greater than 20 microM), when cancer cells were exposed for 4 or 24 h to the drugs. The low cytotoxicity of Epi-glu was most likely due to the reduced cellular uptake rate of the prodrug (2.7 pmol 10(-6) cells min-1) as compared to that of the parent compound (25 pmol 10(-6) cells min-1). Pretreatment of antigen-positive cells with the 323/A3-GUS conjugate prior to prodrug exposure completely restored cytotoxicity as a result from hydrolysis of Epi-glu into Epi. Our results demonstrate that the 323/A3-GUS conjugate can specifically activate the stable non-toxic prodrug Epi-glu at the tumour cell level.

Isolation of an immunodominant viral peptide that is endogenously bound to the stress protein GP96/GRP94.

Heat shock protein gp96 primes class I restricted cytotoxic T cells against antigens present in the cells from which it was isolated. Moreover, gp96 derived from certain tumors functions as an effective vaccine, causing complete tumor regressions in in vivo tumor challenge protocols. Because tumor-derived gp96 did not differ from gp96 isolated from normal tissues, a role for gp96 as a peptide carrier has been proposed. To test this hypothesis, we analyzed whether such an association of antigenic peptides with gp96 occurs in a well-defined viral model system. Here we present the full characterization of an antigenic peptide that endogenously associates with the stress protein gp96 in cells infected with vesicular stomatitis virus (VSV). This peptide is identical to the immunodominant peptide of VSV, which is also naturally presented by H-2Kb major histocompatibility complex class I molecules. This peptide associates with gp96 in VSV-infected cells regardless of the major histocompatibility com- plex haplotype of the cell. Our observations provide a biochemical basis for the vaccine function of gp96.

Early apoptosis largely accounts for functional impairment of CD34+ cells in frozen-thawed stem cell grafts.

Quality assessment of stem cell grafts is usually performed by flow cytometric CD34(+) enumeration or assessment of clonogenic output of fresh material. Previously, we identified the occurrence of early apoptosis, not detectable with the permeability marker 7-amino actinomycin D (7-AAD), in purified frozen-thawed CD34(+) cells, using the vital stain Syto16. Syto(high)/7-AAD(-) cells were defined as viable, Syto16(low)/7-AAD(-) cells as early apoptotic and Syto16(low)/7-AAD(+) as dead. This was confirmed in a subsequent study using frozen-thawed transplants of lymphoma patients. In the present study on grafts from multiple myeloma and lymphoma patients, we investigated the functional consequences of the early apoptotic process. The mean Syto16-defined viability was 41 and 42%, respectively, for both graft groups, compared to 78% and 72%, respectively, using 7-AAD only. The established early apoptosis marker annexin V missed roughly 50% of the early apoptosis detected with Syto16. In contrast, viability of CD34(+) cells in nonmanipulated whole blood transplants from a matched group of lymphoma patients, after 72 h of storage at 4 degrees C, was more than 90%, even with the Syto16 assay. CFU recovery (median 26-33%) after cryopreservation matched CD34(+) recovery after Syto16, but not 7-AAD correction. In contrast, colony-forming unit (CFU) recovery in the whole blood transplant was close to 100%. Furthermore, early apoptotic CD34(+) cells had lost migratory ability toward stromal cell derived factor-1alpha (SDF-1alpha). The establishment of a Syto16(high)/7-AAD(-) proportion of CD34(+) cells offers a new approach for a more correct determination of the number of viable nonapoptotic CD34(+) cells in stem cell grafts. Further development of this assay should allow its incorporation into the routine CD34(+) assessment of post-thawed samples in clinical flow cytometry laboratories.