Evaluation of human hemopoietic stem cell assays for transplantation and gene therapy

Hemopoietic stem cell transplantation has become an important treatment modality for various hematological and non-hematological diseases, e.g. leukemia, lymphoma, congenital immunodeficiencies, autoimmune disease as well as solid tumors. In addition, the use of hemopoietic stem cell transplantation to induce donor-specific tolerance for organ transplantation is explored. Due to increased use of graft manipulation prior to transplantation, including tumor cell purging, stem cell expansion or gene therapy, there is a strong need for in vitro assays able to assess the number and the quality of human in vivo repopulating stem cells. The stromasupported cobblestone area fOrming cell (CAFC) assay allows for determination of the frequency of progenitor cell subsets in various hemopoietic materials. Additionally, the stromasupported flask long-term culture colony-forming cell (LTC-CFC) assay provides means to assess the quality of the graft by determining the ability of the progenitor cells in the graft to produce progeny. Both assays have been extensively studied in the murine model and good correlations have been established with in vivo assays for transient and permanent engrafting stem cell subsets (1-5). The work described in this thesis aims to clarify whether the CAFC and LTC-CFC assays provide a reliable measure for the human in vivo repopulating stem cells as well. In order to accomplish this, we have determined CAFC and LTC-CFC subsets in human mobilized peripheral blood (MPB) and bone marrow (BM) grafts, and correlated them with clinical parameters reflecting reconstitution of transplanted patients. In addition, data from in vitro assays were compared with those generated in a humanized immunodeficient mouse model

Practice based evidence based practice: navigating complexity in feedback-informed systemic therapy

In this thesis I present a research-based account of designing and practising manualised systemic family therapy and doing practice-based, collaborative work. Some time ago my colleague Bruno Hillewaere and I were asked to start providing standardised, evidence-based systemic therapy. In reviewing the range of standardised approaches that were available at the time, we decided we could not commit to a single model or treatment manual. Our experience suggested to us that in times when therapy derives its legitimacy from control, standardised protocols and benchmarking, little attention is paid to the therapist’s improvisations and those small, unpredictable and non-replicable differences that can make the difference for family members. Accordingly, we decided to develop, describe and research our own family therapy practice that was full of improvisations in response to the exchanges that take place, from one moment to the next, in the context of family therapy. In this thesis I present this work. I refer to it as Practice Based Evidence Based Practice (PBEBP). This thesis traces the ways in which I co-developed, applied and used a fluid manual of Feedback-informed Integrative Therapy within Systems (FITS) as a Practice Based Evidence Based Practice (PBEBP) within the bio-cultural matrix that embeds. I present a theoretical framework, inspired by Neo-Materialism, that integrates cybernetics and social-constructionism in contemporary systemic thinking. The question I ask is how to navigate complexity and offer accountability about the process of systemic learning, without getting drawn into the paradoxical spiral of control. I suggest ways in which therapists may become systemic nomads and describe how to produce ‘validity from within’, remaining open to the unpredictable process of becoming in multi-actor networks of human and non-human generators. I show how the fluid manual of FITS corresponds to the locality and complexity of social and cultural life. FITS as PBEBP is substantiated by collaborative practice-based and generative research. The therapist is both practitioner and researcher and involves clients as co-researchers. Therapist and clients examine the effects of their collaboration. The output of research is input for therapy in the ‘collaborative learning community’ constituted together. I have analysed eight cases of completed FITS therapies with families. I promote collaborative learning through coordinated improvisation, organised feedback and mixed-methods research. Accountability and transparency are provided by the quantitative measurement of developments and collaboration in therapy and the qualitative inquiry of therapist’s navigating practice and collaborative learning. I use quantitative measurements as a prelude to evaluative conversation. I analyse critical moments in the transcripts of those conversations. I discover how therapy practice and research effectively intertwine. I hope to inspire systemic practitioners to manualise and research their own practices as a Practice Based Evidence Based Practice. FITS as PBEBP provides ‘validity from within’ in local and singular cases. This approach is an affirmative and transparent alternative to standardisation of protocols and methods in the field of mental healthcare generally and family therapy specifically

European Conditional Marketing Authorization in a Rapidly Evolving Treatment Landscape: A Comprehensive Study of Anticancer Medicinal Products in 2006-2020

Since 2006, the European conditional marketing authorization (CMA) aims to facilitate timely patient access to medicinal products for which there is an unmet medical need by accepting less comprehensive data than normally required. The granting of CMA requires a positive benefit-risk balance, unmet medical needs to be fulfilled, likely submission of comprehensive data postauthorization, and the benefit of immediate availability to outweigh the risks of data noncomprehensiveness. Since its first use, more than half of all CMAs represent (hemato-)oncology indications. Therefore, we aimed to investigate the conditions in which CMA has been applied for anticancer medicinal products and whether they have changed over time. We retrospectively assessed the European public assessment reports of the 30 anticancer medicinal products granted CMA in 2006-2020 (51% of all 59 CMAs). Comparison of 2006-2013 to 2014-2020 highlighted increased proportions of proactively requested CMAs (+40%), medicinal products that addressed unmet medical needs by providing a major therapeutic advantage over authorized treatments (+38%), and orphan designated indications (+32%). In contrast, it showed decreased proportions of medicinal products for which a scientific advisory group was consulted (-55%) and phase III randomized controlled trial data were available (-38%). This suggests that applicants and the European Medicines Agency have learned how to use the CMA as a regulatory tool, among others, through better planning and proactive interaction. However, the increasing number of granted CMAs complicates the establishment of unmet medical need and the benefit-risk balance, especially in crowded indications and when only phase II uncontrolled trials are available

A Comparison of Post-marketing Measures Imposed by Regulatory Agencies to Confirm the Tissue-Agnostic Approach

There are currently four anti-cancer medicinal products approved for a tissue-agnostic indication. This is an indication based on a common biological characteristic rather than the tissue of origin. To date, the regulatory experience with tissue-agnostic approvals is limited. Therefore, we compared decision-making aspects of the first tissue-agnostic approvals between the Food and Drug Administration (FDA), European Medicines Agency (EMA) and Pharmaceuticals and Medical Devices Agency (PMDA). Post-marketing measures (PMMs) related to the tissue-agnostic indication were of specific interest. The main data source was the publicly available review documents. The following data were collected: submission date, approval date, clinical trials and datasets, and PMMs. At the time of data collection, the FDA and PMDA approved pembrolizumab, larotrectinib, and entrectinib for a tissue-agnostic indication, while the EMA approved larotrectinib and entrectinib for a tissue-agnostic indication. There were differences in analysis sets (integrated vs. non-integrated), submission dates and requests for data updates between agencies. All agencies had outstanding issues that needed to be addressed in the post-market setting. For pembrolizumab, larotrectinib and entrectinib, the number of imposed PMMs varied between one and eight, with the FDA requesting the most PMMs compared to the other two agencies. All agencies requested at least one PMM per approval to address the remaining uncertainties related to the tissue-agnostic indication. The FDA and EMA requested data from ongoing and proposed trials, while the PMDA requested data from use-result surveys. Confirmation of benefit in the post-marketing setting is an important aspect of tissue-agnostic approvals, regardless of agency. Nonetheless, each approach to confirm benefit has its inherent limitations. Post-marketing data will be essential for the regulatory and clinical decisions-making of medicinal products with a tissue-agnostic indication

A Rac1 inhibitory peptide suppresses antibody production and paw swelling in the murine collagen-induced arthritis model of rheumatoid arthritis

Introduction: The Rho family GTPase Rac1 regulates cytoskeletal rearrangements crucial for the recruitment, extravasation and activation of leukocytes at sites of inflammation. Rac1 signaling also promotes the activation and survival of lymphocytes and osteoclasts. Therefore, we assessed the ability of a cell-permeable Rac1 carboxy-terminal inhibitory peptide to modulate disease in mice with collagen-induced arthritis (CIA). Methods: CIA was induced in DBA/1 mice, and in either early or chronic disease, mice were treated three times per week by intraperitoneal injection with control peptide or Rac1 inhibitory peptide. Effects on disease progression were assessed by measurement of paw swelling. Inflammation and joint destruction were examined by histology and radiology. Serum levels of anti-collagen type II antibodies were measured by enzyme-linked immunosorbent assay. T-cell phenotypes and activation were assessed by fluorescence-activated cell sorting analysis. Results were analyzed using Mann-Whitney U and unpaired Student t tests. Results: Treatment of mice with Rac1 inhibitory peptide resulted in a decrease in paw swelling in early disease and to a lesser extent in more chronic arthritis. Of interest, while joint destruction was unaffected by Rac1 inhibitory peptide, anti-collagen type II antibody production was significantly diminished in treated mice, in both early and chronic arthritis. Ex vivo, Rac1 inhibitory peptide suppressed T-cell receptor/CD28-dependent production of tumor necrosis factor a, interferon. and interleukin-17 by T cells from collagen-primed mice, and reduced induction of ICOS and CD154, T-cell costimulatory proteins important for B-cell help. Conclusions: The data suggest that targeting of Rac1 with the Rac1 carboxy-terminal inhibitory peptide may suppress T-cell activation and autoantibody production in autoimmune disease. Whether this could translate into clinically meaningful improvement remains to be show

The EMA Assessment of Asciminib for the Treatment of Adult Patients With Philadelphia Chromosome-Positive Chronic Myeloid Leukemia in Chronic Phase Who Were Previously Treated With at Least Two Tyrosine Kinase Inhibitors

Asciminib is an allosteric high-affinity tyrosine kinase inhibitor (TKI) of the BCR-ABL1 protein kinase. This kinase is translated from the Philadelphia chromosome in chronic myeloid leukemia (CML). Marketing authorization for asciminib was granted on August 25, 2022 by the European Commission. The approved indication was for patients with Philadelphia chromosome-positive CML in the chronic phase which have previously been treated with at least 2 TKIs. Clinical efficacy and safety of asciminib were evaluated in the open-label, randomized, phase III ASCEMBL study. The primary endpoint of this trial was major molecular response (MMR) rate at 24 weeks. A significant difference in MRR rate was shown between the asciminib treated population and the bosutinib control group (25.5% vs. 13.2%, respectively, P=.029). In the asciminib cohort, adverse reactions of at least grade 3 with an incidence≥5% were thrombocytopenia, neutropenia, increased pancreatic enzymes, hypertension, and anemia. The aim of this article is to summarize the scientific review of the application which led to the positive opinion by the European Medicines Agency's Committee for Medicinal Products for Human Use.</p

Single-arm trials supporting the approval of anticancer medicinal products in the European Union: contextualization of trial results and observed clinical benefit

Background: Single-arm trials (SATs) can sometimes be used to support marketing authorization of anticancer medicinal products in the European Union. The level and durability of antitumor activity of the product as well as context are important aspects to determine the relevance of trial results. The aim of this study is to provide details on the contextualization of trial results and to evaluate the magnitude of benefit of medicinal products approved based on SATs. Materials and methods: We focused on anticancer medicinal products for solid tumors approved on the basis of SAT results (2012-2021). Data were retrieved from European public assessment reports and/or published literature. The benefit of these medicinal products was evaluated via the European Society for Medical Oncology (ESMO)-Magnitude of Clinical Benefit Scale (MCBS). Results: Eighteen medicinal products were approved based on 21 SATs—few medicinal products were supported by >1 SAT. For the majority of clinical trials, a clinically relevant treatment effect was (pre)specified (71.4%) and most often an accompanying sample size calculation was provided. For 10 studies, each testing a different medicinal product, a justification for the threshold for a clinically relevant treatment effect could be identified. At least 12 out of 18 applications included information to facilitate the contextualization of trial results, including six supportive studies. Of the pivotal SATs analyzed (n = 21), three were assigned an ESMO-MCBS score of 4, which corresponds to ‘substantial’ benefit. Conclusions: The clinical relevance of the treatment effects shown by medicinal products for solid tumors tested in SATs is dependent on the effect size and context. To better facilitate regulatory decision making, prespecifying and motivating a clinically relevant effect and aligning the sample size to that effect is important. External controls may facilitate in the contextualization process, but the associated limitations must be addressed

14-3-3 Proteins Interact with a Hybrid Prenyl-Phosphorylation Motif to Inhibit G Proteins

Signaling through G proteins normally involves conformational switching between GTP- and GDP-bound states. Several Rho GTPases are also regulated by RhoGDI binding and sequestering in the cytosol. Rnd proteins are atypical constitutively GTP-bound Rho proteins, whose regulation remains elusive. Here, we report a high-affinity 14-3-3-binding site at the C terminus of Rnd3 consisting of both the Cys241-farnesyl moiety and a Rho-associated coiled coil containing protein kinase (ROCK)-dependent Ser240 phosphorylation site. 14-3-3 binding to Rnd3 also involves phosphorylation of Ser218 by ROCK and/or Ser210 by protein kinase C (PKC). The crystal structure of a phosphorylated, farnesylated Rnd3 peptide with 14-3-3 reveals a hydrophobic groove in 14-3-3 proteins accommodating the farnesyl moiety. Functionally, 14-3-3 inhibits Rnd3-induced cell rounding by translocating it from the plasma membrane to the cytosol. Rnd1, Rnd2, and geranylgeranylated Rap1A interact similarly with 14-3-3. In contrast to the canonical GTP/GDP switch that regulates most Ras superfamily members, our results reveal an unprecedented mechanism for G protein inhibition by 14-3-3 proteins