Prevalence, Severity, and Clinical Management of Brain Incidental Findings in Healthy Young Adults: MRi-Share Cross-Sectional Study.

Background and Objectives: Young adults represent an increasingly large proportion of healthy volunteers in brain imaging research, but descriptions of incidental findings (IFs) in this age group are scarce. We aimed to assess the prevalence and severity of IFs on brain MRIs of healthy young research participants aged 18-35 years, and to describe the protocol implemented to handle them. Methods: The study population comprised 1,867 participants aged 22.1 ± 2.3 years (72% women) from MRi-Share, the cross-sectional brain MRI substudy of the i-Share student cohort. IFs were flagged during the MRI quality control. We estimated the proportion of participants with IFs [any, requiring medical referral, potentially serious (PSIFs) as defined in the UK biobank]: overall, by type and severity of the final diagnosis, as well as the number of IFs. Results: 78/1,867 participants had at least one IF [4.2%, 95% Confidence Interval (CI) 3.4-5.2%]. IFs requiring medical referral (n = 38) were observed in 36/1,867 participants (1.9%, 1.4-2.7%), and represented 47.5% of the 80 IFs initially flagged. Referred IFs were retrospectively classified as PSIFs in 25/1,867 participants (1.3%, 0.9-2.0%), accounting for 68.4% of anomalies referred (26/38). The most common final diagnosis was cysts or ventricular abnormalities in all participants (9/1,867; 0.5%, 0.2-0.9%) and in those with referred IFs (9/36; 25.0%, 13.6-41.3%), while it was multiple sclerosis or radiologically isolated syndrome in participants with PSIFs (5/19; 26.3%, 11.5-49.1%) who represented 0.1% (0.0-0.4%) and 0.2% (0.03-0.5%) of all participants, respectively. Final diagnoses were considered serious in 11/1,867 participants (0.6%, 0.3-1.1%). Among participants with referred IFs, 13.9% (5/36) required active intervention, while 50.0% (18/36) were put on clinical surveillance. Conclusions: In a large brain imaging study of young healthy adults participating in research we observed a non-negligible frequency of IFs. The etiological pattern differed from what has been described in older adults.

Radioimmunotherapy for Treatment of Acute Leukemia.

Acute leukemias are characterized by accumulation of immature cells (blasts) and reduced production of healthy hematopoietic elements. According to the lineage origin, two major leukemias can be distinguished: acute myeloid leukemia (AML) and acute lymphoid leukemia (ALL). Although the survival rate for pediatric ALL is close to 90%, half of the young adults with AML or ALL and approximately 90% of older patients with AML or ALL still die of their disease, raising the need for innovative therapeutic approaches. As almost all leukemic blasts express specific surface antigens, targeted immunotherapy appears to be particularly promising. However, published results of immunotherapy alone are generally modest. Radioimmunotherapy (RIT) brings additional therapeutic mechanisms using radiolabeled monoclonal antibodies (mAbs) directed to tumor antigens, thus adding radiobiological cytotoxicity to immunologic cytotoxicity. Because of the high radiosensitivity of tumor cells and the diffuse widespread nature of the disease, making it rapidly accessible to circulating radiolabeled mAbs, acute leukemias represent relevant indications for RIT. With the development of recombinant and humanized mAbs, innovative radionuclides, and more efficient radiolabeling and pretargeting techniques, RIT has significantly improved over the last 10 years. Different approaches of α and ß RIT targeting CD22, CD33, CD45, or CD66 antigens have already been evaluated or are currently being developed in the treatment of acute leukemia. This review summarizes the preclinical and clinical studies demonstrating the potential of RIT in treatment of AML and ALL.

Cancer radioimmunotherapy with alpha-emitting nuclides.

In lymphoid malignancies and in certain solid cancers such as medullary thyroid carcinoma, somewhat mixed success has been achieved when applying radioimmunotherapy (RIT) with beta-emitters for the treatment of refractory cases. The development of novel RIT with alpha-emitters has created new opportunities and theoretical advantages due to the high linear energy transfer (LET) and the short path length in biological tissue of alpha-particles. These physical properties offer the prospect of achieving selective tumoural cell killing. Thus, RIT with alpha-emitters appears particularly suited for the elimination of circulating single cells or cell clusters or for the treatment of micrometastases at an early stage. However, to avoid non-specific irradiation of healthy tissues, it is necessary to identify accessible tumoural targets easily and rapidly. For this purpose, a small number of alpha-emitters have been investigated, among which only a few have been used for in vivo preclinical studies. Another problem is the availability and cost of these radionuclides; for instance, the low cost and the development of a reliable actinium-225/bismuth-213 generator were probably determining elements in the choice of bismuth-213 in the only human trial of RIT with an alpha-emitter. This article reviews the literature concerning monoclonal antibodies radiolabelled with alpha-emitters that have been developed for possible RIT in cancer patients. The principal radio-immunoconjugates are considered, starting with physical and chemical properties of alpha-emitters, their mode of production, the possibilities and difficulties of labelling, in vitro studies and finally, when available, in vivo preclinical and clinical studies.

Selective blockade of CD28 and not CTLA-4 with a single-chain Fv-alpha1-antitrypsin fusion antibody.

B7-1 and B7-2 are costimulatory molecules expressed on antigen-presenting cells. The CD28/B7 costimulation pathway is critical for T-cell activation, proliferation, and Th polarization. Blocking both cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) and CD28 interactions with a CTLA-4/Ig fusion protein inhibits various immune-mediated processes in vivo, such as allograft rejection and autoimmunity. However, selective blockade of CD28 may represent a better strategy for immunosuppression than B7 blockade, because CTLA-4/B7 interactions have been shown to participate in the extinction of the T-cell receptor-mediated activation signal and to be required for the induction of immunologic tolerance. In addition, selective CD28 inhibition specifically decreases the activation of alloreactive and autoreactive T cells, but not the activation of T cells stimulated by exogenous antigens presented in the context of self major histocompatibility complex (MHC) molecules. CD28 blockade cannot be obtained with anti-CD28 dimeric antibodies, which cluster their target and promote T-cell costimulation, whereas monovalent Fab fragments can block CD28 and reduce alloreactivity. In this study, we report the construction of a monovalent single-chain Fv antibody fragment from a high-affinity antihuman CD28 antibody (CD28.3) that blocked adhesion of T cells to cells expressing the CD28 receptor CD80. Genetic fusion with the long-lived serum protein alpha1-antitrypsin led to an extended half-life without altering its binding characteristics. The anti-CD28 fusion molecule showed biologic activity as an immuno-suppressant by inhibiting T-cell activation and proliferation in a mixed lymphocyte reaction.