Controlled
Delivery of Biotechnological Products. Pp. 313-323.
S. Conti, L. Polonelli, R. Frazzi, M.
Artusi, R. Bettini, D. Cocconi and P. Colombo
Mitochondriotropic Cationic Vesicles: A Strategy Towards Mitochondrial Gene Therapy. Pp. 325-346.
V. Weissig
and V. P. Torchilin
N-Glycosylation
of Recombinant Pharmaceutical Glycoproteins Produced in Transgenic Plants:
Towards an Humanisation of Plant N-Glycans. Pp.. 347-354.
P. Lerouge,
M. Bardor, S. Pagny, V. Gomord and L. Faye
Structure
Alteration of Polyketides by Recombinant DNA Technology in Producer Organisms -
Prospects for the Generation of Novel Pharmaceutical Drugs. Pp. 355-395.
Carmen
Méndez, Gabriele Weitnauer, Andreas Bechthold and José A. Salas
[Back to top] Antibody-Targeted Immunotherapy for Treatment of Non-Hodgkin’s Lymphoma.
The
scientific development of immunotherapies and radioimmunotherapies of cancer
began more than four decades ago. Over time, it has become apparent that the
choice of target antigen, immunogenicity of antibodies, length of antibody
half-life, ability of antibodies to recruit immune effector functions, decision
on conjugation of antibodies to toxins or radionuclides and antibody
manufacturing are critical components of successful development of an
immunotherapeutic regimen. Anti-idiotype antibodies were some of the first
successful monoclonal antibody treatments developed for non-Hodgkin’s lymphoma.
In 1997, the chimeric antibody, Rituximab, was approved by the United States
Food and Drug Administration for treatment of patients with relapsed or
refractory low-grade or follicular non-Hodgkin’s lymphoma. In an effort to
enhance the efficacy of immunotherapy, toxins and radionuclides have been
conjugated to monoclonal antibodies. Ibritumomab, the parent murine antibody of
Rituximab, is conjugated to the radioisotope 90Y to create 90Y
Ibritumomab tiuxetan, (90Y Zevalin, IDEC‑Y2B8). Promising
Phase I/II trials have been completed. Phase III experimental trials of 90Y
Ibritumomab tiuxetan as treatment for relapsed or refractory NHL are in
progress.
[Back to
top] Controlled Delivery of Biotechnological
Products.
Peptides,
proteins, and nucleotides or DNA fragments are the new generation of drugs.
They are becoming attractive owing to the fast development of biotechnology.
The admnistration of such molecules, however, may be a problem as sensitivity
to temperature, instability at some physiological pH values, short plasma
half-life, and high molecular dimension, which hinders the diffusive transport,
make, at the moment, parenteral route the only possible way of administration
of such molecules.
Controlled
drug delivery that comprises the development of new administration routes could
be the answer to the problems for administration of biotechnological molecules.
The
rational of drug delivery is to change the pharmacokinetic and pharmacodynamic
of drugs by controlling their absorption and distribution. Rate and time of
drug release at absorption site could be programmed using a so called delivery
system. Different technologies, such as chemical (pro-drugs), biological,
polymers, lipids (liposomes, LDL), have been proposed to obtain controlled drug
release. Also the use of new administration routes is part of controlled drug
delivery. In fact, it could increase the drug absorption and reduce the effects
of the active ingredient in those districts not interested in the therapy.
Drug
delivery systems allowing for an effective release in vivo of new biotechnological molecules, such as recombinant
antiidiotypic antibodies with antibiotic activity, devoted to the treatment of
pulmonary (tuberculosis and pneumocystosis) and mucosal (candidiasis) diseases
are discussed under that perspective.
[Back to
top] Mitochondriotropic
Cationic Vesicles: A Strategy Towards Mitochondrial Gene Therapy.
The number of diseases found to be associated with defects of the mitochondrial
genome has grown significantly over the last decade. Despite major advances in understanding mtDNA defects at the genetic and
biochemical level, there is no satisfactory treatment for the vast majority of
patients available. This is largely due to the fact that almost all
mitochondrial DNA defects involve the final common pathway of oxidative
metabolism making it impossible to bypass the defect by giving alternative
metabolic carriers of energy. These seemingly objective limitations of conventional
biochemical treatment for patients with defects of mtDNA warrant the
exploration of gene therapeutic approaches. However, mitochondrial gene
therapy still appears only theoretical and speculative. Any possibility for
gene replacement is dependent on the use of a yet unavailable
mitochondria-specific transfection vector.
Based
upon an analysis of the self-assembly behavior of dequalinium, a cationic
single-chain bolaamphiphile which is known to selectively accumulate in
mitochondria, we have developed a whole new strategy for mitochondria-specific
DNA delivery. We have succeeded in preparing vesicles made of dequalinium,
which we termed DQAsomes (U.S. Patent 6,090,619). We have shown that DQAsomes
efficiently bind and protect DNA and we could demonstrate that DQAsome/DNA
complexes selectively release DNA at cardiolipin-rich liposomes mimicking both,
the inner and the outer mitochondrial membrane. Based on the intrinsic property
of dequalinium to preferentially accumulate in mitochondria in response to the
electrochemical gradient at the mitochondrial membrane and based on the
selective DNA release at mitochondria-like membranes we propose DQAsomes as the
first mitochondria-specific vector to deliver DNA to mitochondria in living
cells.
[Back to top] N-Glycosylation of Recombinant Pharmaceutical Glycoproteins Produced in Transgenic Plants: Towards an Humanisation of Plant N-Glycans.
The number of
therapeutic proteins successfully produced in plants is steadily increasing and
is expected to grow even more rapidly in the future. Most therapeutic proteins
are glycoproteins and N-glycosylation is often essential for their stability,
folding and biological activity. Recombinant glycoproteins of mammalian origin
expressed in transgenic plants largely retain their biological activity.
However, plants are not ideal for production of pharmaceutical proteins because
they produce molecules with glycans that are not compatible with therapeutic
applications in humans. As a consequence, strategies to humanise plant
N-glycans are now developed. Some of these strategies involve the retention of
the recombinant glycoprotein in the endoplasmic reticulum while others are
related to the inhibition of endogenous Golgi glycosyltransferases or addition
of “new” glycosyltransferases. Data on both the N-glycosylation of therapeutic
glycoproteins produced in transgenic plants and current strategies to humanise
their N-glycosylation will be discussed in this review.
[Back to
top] Structure Alteration of
Polyketides by Recombinant DNA Technology in Producer Organisms - Prospects for
the Generation of Novel Pharmaceutical Drugs.
Actinomycetes are
gram-positive bacteria and commercially important microorganisms. They are
producers of approximately two thirds of all bioactive compounds known and they
produce a great variety of compounds which have clinical application on the
basis of their activity against different kinds of organisms and cells as
antibacterial (macrolides, avermectins), antitumor (anthracyclines,
angucyclines, aureolic acid group) and also compounds showing immunosuppresant
activity (rapamycin, FK506). Most of these clinically useful pharmaceuticals
produced by actinomycetes belong to the polyketide family. Polyketides comprise
a wide family of chemically diverse compounds, many of which have shown
bioactivity. The development of recombinant DNA technology has opened a new and
exciting field of research for the generation of new bioactive compounds
through genetic manipulation of the biosynthetic pathways. Researchers in this
area are trying to take advantage of the enormous capability of actinomycetes
to produce pharmaceutically useful compounds in order to manipulate the
different biosynthetic pathways and subsequently generate novel drugs.
Combinatorial biosynthesis is now emerging as a powerful tool to generate novel
families of compounds by interchanging secondary metabolism genes between
bioactive producing actinomycetes. Novel compounds will be the consequence of
the concerted action of enzymes from different, but related, biosynthetic
pathways. Insertional inactivation of selected genes and tailoring modification
may also produce novel compounds that can be useful pharmaceuticals or lead
compounds for further chemical modification. This minireview will present the
state of the art in this field showing the different polyketides biosynthetic
pathways so far characterized and how the identified genes are being used to
generate structural biodiversity. Emphasis will be made on the polyketide
family including type I and type II polyketides.