A phase I/II study of recombinant interferon alpha 2a and hydroxyurea for chronic myelocytic leukemia

Nine previously untreated patients with Philadelphia chromosome-positive chronic myelocytic leukemia (CML) were treated with recombinant interferon alpha 2a (rIFN-alpha 2a) and hydroxyurea. Patients received 6 X 10(6) U rIFN-alpha 2a daily for the first week and 3 X 10(6) U rIFN-alpha 2a daily for the second week. As maintenance treatment starting on day 15, patients received 3 X 10(6) U rIFN-alpha 2a 3 times a week. Simultaneously, hydroxyurea was given, starting at a dose of 40 mg/kg on day one. The maintenance dosage was adjusted to the white blood cell count. Two patients responded with complete hematological remissions but without cytogenetic and molecular-genetic improvements. Seven patients responded with partial hematological remissions. Response to therapy was rapid; normal white blood cell counts were reached after a median of 12 days. The doses of rIFN-alpha 2a and hydroxyurea needed to keep the leucocyte count in the normal range were low (3 X 10(6) U rIFN-alpha 2a 3 times per week, 0.5-1.5 g hydroxyurea/day). Acute toxicity of the combination therapy consisted of fever (9 of 9 patients), flulike symptoms (7 of 9 patients), pruritus and/or rash (3 of 9 patients) and evidence of a tumor cell lysis syndrome (1 of 9 patients). The side effects were not dose-limiting. Combination therapy with rIFN-alpha 2a and hydroxyurea for CML is well tolerated and allows quick and effective hematological control of the disease.     

Hydroxycarbamide: Clinical aspects

Due to its oral route of administration and mild toxicity profile, as well as its potent laboratory and clinical effects, hydroxyurea (or hydroxycarbamide) has been the primary focus of fetal hemoglobin (HbF) induction strategies for the treatment of children with sickle cell anemia (SCA). When administered orally once a day, hydroxyurea treatment is very well tolerated with little short-term toxicity. Hydroxyurea has documented laboratory efficacy with increases in Hb and HbF; treatment also significantly reduces the number of painful episodes, acute chest syndrome, transfusions, and hospitalizations. Most young patients reach a maximum tolerated dose of hydroxyurea at 25–30 mg/kg/d, where they will achieve key laboratory thresholds (Hb ≥ 9 g/dL and HbF ≥ 20%) without excessive myelosuppression. Potential long-term toxicities continue to be of great concern and should be monitored in all patients with SCA who receive hydroxyurea therapy. To date, however, no increases in stroke, myelodysplasia, or carcinogenicity have been detected in SCA patient cohorts, with drug exposure now reaching 15 years for some treated children. Taken together, available evidence suggests that hydroxyurea represents an inexpensive and effective treatment option that should be offered to most, if not all, patients with SCA. As countries in Africa develop newborn screening programs to identify SCA, the widespread use of hydroxyurea may prove to be a useful treatment to help ameliorate the disease in resource-limited settings. Hydroxyurea is the only currently available disease-modifying therapy for SCA, and is emerging as a safe and effective treatment for all patients with SCA, in both developed and developing countries.     

Inhibition of clinical human immunodeficiency virus (HIV) type 1 isolates in primary CD4+ T lymphocytes by retroviral vectors expressing anti-HIV genes.

Gene therapy may be of benefit in human immunodeficiency virus type 1 (HIV-1)-infected individuals by virtue of its ability to inhibit virus replication and prevent viral gene expression. It is not known whether anti-HIV-1 gene therapy strategies based on antisense or transdominant HIV-1 mutant proteins can inhibit the replication and expression of clinical HIV-1 isolates in primary CD4+ T lymphocytes. We therefore transduced CD4+ T lymphocytes from uninfected individuals with retroviral vectors expressing either HIV-1-specific antisense-TAR or antisense-Tat/Rev RNA, transdominant HIV-1 Rev protein, and a combination of antisense-TAR and transdominant Rev. The engineered CD4+ T lymphocytes were then infected with four different clinical HIV-1 isolates. We found that replication of all HIV-1 isolates was inhibited by all the anti-HIV vectors tested. Greater inhibition of HIV-1 was observed with transdominant Rev than with antisense RNA. We hereby demonstrated effective protection by antisense RNA or transdominant mutant proteins against HIV-1 infection in primary CD4+ T lymphocytes using clinical HIV-1 isolates, and this represents an essential step toward clinical anti-HIV-1 gene therapy.     

Circulating monocytes are not a major reservoir of HIV-1 in elite suppressors

Circulating HIV-1-infected monocytes have been identified in patients on highly active antiretroviral therapy and may represent an important barrier to viral eradication. The nature of these cells in HIV-1-infected patients who maintain undetectable viral loads and preserved CD4(+) T cell counts without antiretroviral therapy (known as elite controllers or elite suppressors [ES]) is unknown. We describe here infrequent recovery of proviral HIV-1 DNA from circulating monocytes relative to CD4(+) T cells in ES, despite permissiveness of these cells to HIV-1 viral entry ex vivo. Thus, monocytes do not appear to be a major reservoir of HIV-1 in ES.     

Updates on CRISPR-based gene editing in HIV-1/AIDS therapy

Although tremendous efforts have been made to prevent and treat HIV-1 infection, HIV-1/AIDS remains a major threat to global human health. The combination antiretroviral therapy (cART), although able to suppress HIV-1 replication, cannot eliminate the proviral DNA integrated into the human genome and thus requires lifelong treatment that may lead to various side effects. In recent years, clustered regularly interspaced short palindromic repeat (CRISPR)-associated nuclease 9 (Cas9) related gene-editing systems have been developed and designed as effective ways to treat HIV-1 infection. However, new gene-targeting tools derived from or functioning like CRISPR/Cas9, including base editor, prime editing, SHERLOCK, DETECTR, PAC-MAN, ABACAS, pfAGO, have been developed and optimized for pathogens detection and diseases correction. Here, we summarize recent studies on HIV-1/AIDS gene therapy and provide more gene-editing targets based on studies relating to the molecular mechanism of HIV-1 infection. We also identify the strategies and potential applications of these new gene-editing technologies for HIV-1/AIDS treatment in the future. Moreover, we discuss the caveats and problems that should be addressed before the clinical use of these versatile CRISPR-based gene targeting tools. Finally, we offer alternative solutions to improve the practice of gene targeting in HIV-1/AIDS gene therapy.     

Inhibition of angiogenesis by type I interferons in models of Kaposi's sarcoma

Kaposi's Sarcoma (KS) is a pathology which occurs with increased frequency and in a particularly aggressive form in AIDS patients. The HIV-1 Tat protein appears to be an important co-factor in the induction of the extensive neo-vascularization associated with AIDS-KS. Tat acts as a chemoattractant for endothelial cells in vitro, inducing both chemotactic and invasive responses. Several clinical trials have been performed testing the effectiveness of diverse biological agents in therapy of KS, among these the type I interferons. Type I IFNs have diverse biological functions besides their anti-viral activity, including anti-angiogenic properties. We have shown that IFN alpha and IFN beta are potent inhibitors of both primary and immortalized endothelial cell migration and morphogenesis in vitro as well as neo-angiogenesis induced by HIV-1 Tat in vivo. The inhibitory effect of IFN class I on HIV-Tat associated angiogenesis further supports its use as a therapy for epidemic Kaposi's sarcoma. The use of recombinant IFNs at the levels required to obtain a therapeutic effect are associated with side effects and toxicity, therefore we are now developing a gene therapy approach for constant and local delivery type I IFNs.     

Current views on <Emphasis>HIV-1</Emphasis> latency,persistence, and cure

HIV-1 infection cannot be cured as it persists in latently infected cells that are targeted neither by the immune system nor by available therapeutic approaches. Consequently, a lifelong therapy suppressing only the actively replicating virus is necessary. The latent reservoir has been defined and characterized in various experimental models and in human patients, allowing research and development of approaches targeting individual steps critical for HIV-1 latency establishment, maintenance, and reactivation. However, additional mechanisms and processes driving the remaining low-level HIV-1 replication in the presence of the suppressive therapy still remain to be identified and targeted. Current approaches toward HIV-1 cure involve namely attempts to reactivate and purge HIV latently infected cells (so-called “shock and kill” strategy), as well as approaches involving gene therapy and/or gene editing and stem cell transplantation aiming at generation of cells resistant to HIV-1. This review summarizes current views and concepts underlying different approaches aiming at functional or sterilizing cure of HIV-1 infection.     

Hydroxyurea Could Be a Good Clinically Relevant Iron Chelator

Our previous study showed a reduction in serum ferritin of β-thalassemia patients on hydroxyurea therapy. Here we aimed to evaluate the efficacy of hydroxyurea alone and in combination with most widely used iron chelators like deferiprone and deferasirox for reducing iron from experimentally iron overloaded mice. 70 BALB/c mice received intraperitonial injections of iron-sucrose. The mice were then divided into 8 groups and were orally given hydroxyurea, deferiprone or deferasirox alone and their combinations for 4 months. CBC, serum-ferritin, TBARS, sTfr and hepcidin were evaluated before and after iron overload and subsequently after 4 months of drug therapy. All animals were then killed. Iron staining of the heart and liver tissue was done using Perl’s Prussian Blue stain. Dry weight of iron in the heart and liver was determined by atomic absorption spectrometry. Increased serum-ferritin, TBARS, hepcidin and dry weight of iron in the liver and heart showed a significant reduction in groups treated with iron chelators with maximum reduction in the group treated with a combination of deferiprone, deferasirox and hydroxyurea. Thus hydroxyurea proves its role in reducing iron from iron overloaded mice. The iron chelating effect of these drugs can also be increased if given in combination.     

Adeno-associated virus gene delivery of broadly neutralizing antibodies as prevention and therapy against HIV-1

Vectored gene delivery of HIV-1 broadly neutralizing antibodies (bNAbs) using recombinant adeno-associated virus (rAAV) is a promising alternative to conventional vaccines for preventing new HIV-1 infections and for therapeutically suppressing established HIV-1 infections. Passive infusion of single bNAbs has already shown promise in initial clinical trials to temporarily decrease HIV-1 load in viremic patients, and to delay viral rebound from latent reservoirs in suppressed patients during analytical treatment interruptions of antiretroviral therapy. Long-term, continuous, systemic expression of such bNAbs could be achieved with a single injection of rAAV encoding antibody genes into muscle tissue, which would bypass the challenges of eliciting such bNAbs through traditional vaccination in naïve patients, and of life-long repeated passive transfers of such biologics for therapy. rAAV delivery of single bNAbs has already demonstrated protection from repeated HIV-1 vaginal challenge in humanized mouse models, and phase I clinical trials of this approach are underway. Selection of which individual, or combination of, bNAbs to deliver to counter pre-existing resistance and the rise of escape mutations in the virus remains a challenge, and such choices may differ depending on use of this technology for prevention versus therapy.     

Mechanisms of human immunodeficiency virus type 1 inhibition by hydroxyurea

Virus life cycles depend on cellular factors. Therefore, targeting cellular in combination with viral enzymes could be an effective control in virus replication. In contrast to viral proteins, cellular proteins are not prone to mutations; therefore, viral escape is not expected from drugs inhibiting cellular factors. Hydroxyurea inhibits the cellular enzyme ribonucleotide reductase, thus reducing DNA synthesis. Furthermore, this drug potentiates the activity of nucleoside analogues, inhibits the escape of A-analogue resistant mutants, and increases the phosphorylation of T-analogues. Besides its antiviral activity, hydroxyurea effects the immune system by decreasing immune activation, inhibiting the expansion of CD8 cells and the depletion of CD4 cells. Hydroxyurea has been used in medicine for 40 years, is well tolerated, and it is the least expensive available anti-HIV-1 drug. These characteristics make hydroxyurea a primary candidate for use in combination therapies for the treatment of HIV-1 infection.