Добавил:
Sekretar
kiopkiopkiop18@yandex.ru
t.me/Prokururor I Вовсе не секретарь, но почту проверяю
Опубликованный материал нарушает ваши авторские права? Сообщите нам.
Вуз:
Предмет:
Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_5443_Библиотеки_им_академика_М_И_Перельмана
.pdf
ing has produced chimerized, humanized, and totally human Abs [43]. The majority of
Abs used in humans today are either humanized or developed from humans. With the
exception of the complementarity-determining regions (CDRs), which are derived from
mice, humanized Abs are primarily derived from human sources [44]. Mouse CDRs are
resurfaced or grafted to the human Fv surface and constant areas in humanized Abs (Fig-
ure 17.2). One example of a CDR resurfacing humanized ADC is Kadcyla
®
. Immunoglobu-
lin (Ig)-G1 is the most common human Ig-G isotype seen in most ADCs used in clinical
trials. ADCC and complement-dependent cytotoxicity (CDC) are occasionally induced by
the unmodified Fc sections of Abs binding to Fc-gamma receptors (FcγR) of immune cells,
such as macrophages and natural killer cells. This leads to the development of anticancer
immune responses. Compared to IgG4 and IgG2 mAbs, the effects of ADCC and CDC are
more pronounced in human IgG1 isotype mAbs. For instance, trastuzumab, the medica-
tion included in Kadcyla
®
, has been shown to start ADCC and CDC-associated tumor cell
death. Bispecific Abs have also been produced to improve therapeutic functionality in ad-
dition to monospecific Abs. These are employed to target two tumor cell and tumor-
associated immune cell antigens [45]. The FDA approved blinatumomab, a bispecific T-
cell engager (BiTE), in 2014 to treat acute lymphoblastic leukemia (ALL) with Philadelphia
chromosome loss. There are not many studies on bispecific ADC, and the majority are still
in preclinical research [46]. One such bispecific ADC is called bsHER2xCD63his-ADC, and it
targets the antigens HER2 and CD63, which are found on cancerous cells and are responsi-
ble for communication between intracellular compartments and the cell membrane.
17.9 Linker chemistry
An ADC’s designed linker system, which connects the payload and antibody, is a cru-
cial structural element. Once internalization and trafficking in particular subcellular
compartments have taken place, the linker should be stable in the circulation to en-
able the cytotoxic moiety stay linked to the antibody as it is transported into tumor
tissues, but also to permit effective release [47]. Low-stability linkers are more likely
to undergo nonspecific cleavage, which raises systemic drug levels and broadens the
toxicity profile. The two main categories of linkers are cleavable and noncleavable.
Between the payload and the antibody attachment point, cleavable linkers have a site
that can be the site of cleavage by a variety of processes, such as reductive cleavage of
disulfide bonds, enzymatic cleavage of amide or ester bonds, or hydrolysis of acid-
labile bonds. These reactions could take place in the cytosol or within the endosome
and/or lysosome compartments [48] . The thioether bond-containing noncleavable
linkers necessitate the full lysosomal proteolytic breakdown of the antibody to liber-
ate the ultimate active metabolite. More advanced medicinal chemistry techniques
are being used to develop linker technologies for the creation of ADCs that are more
effective and well-tolerated.
17 Molecular simulation-based technology for antibody–drug conjugates 393
https://t.me/med1917
17.9.1 Linker selection
Due to its significant effects on the therapeutic index, effectiveness, and pharmacoki-
netics of the ADC, the linker plays a crucial role in the outcomes of ADCs [49]. It mini-
mizes off-target effects by preventing the cytotoxic drug from being released before it
reaches the target thanks to the stable linkers in ADCs, which help to maintain the
blood circulation’s concentrat ion of Ab. After the ADC is internalized by the tumor
cells, the linker should, nevertheless, be malleable enough to release the cytotoxic
medication quickly. The number of drug molecules that should be loaded onto the Ab,
or “DAR,” is another crucial factor to take into account. As a result, DAR tuning is re-
quired since attaching too few or too many drug molecules would change the pharma-
cokinetics and increase toxicity and instability, while attaching too few will result in
decreased efficacy [50]. An unfavorable heterogeneous combination of ADCs with
high DAR values was produced by nonspecific conjugation of Abs to lysine residues,
an approach that the FDA has permitted for ADCs with shown action. In order to cre-
ate homogenous ADCs with a large number of drug molecules stably coupled to the
Ab, research efforts are focused in this direction. The majority of ADCs seek to achieve
a DAR value that is nearly equal to four [51].
Antibody
Attachment
site
Linker
Payload
-Target tumor-
specific antigen that
are abundant in tumor
tissue but minimally
expressed in normal
tissue.
-Retain low
immunogenicity
-Conventional
approach through non
specific conjugation of
cysteine or lysine
residue on the antibody
-heterogeneous mixture
variable drug -
antibody ratio (DAR)
-site specific
conjugation
--homogeneous ADCS
-improve stability;
therapeutic window
and overall efficacy
-Cleavage or non
cleavage -stable in
circulation
-selection
intracellular drug
release
-cleaved in tamour
tissue by:
> reduction
> low pH
> protease
> antibody
degradation
-Specific
mechanism
(target either
tubulin or DNA)
- highly potent cell
toxicity
- requires
-Appropriate
conjugate site for
linker attachment
-Has high degree of
specificity, binding
affinity, and stability
-Is Susceptible to
cellular internalization
-Non immune
genic
Figure 17.2: The general components of ADC. Selection principles of antibody, comparison between
nonspecific and specific conjugations, and descriptions on how the drug is released and its mechanism of
action.
394 Abhishek Singh et al.
https://t.me/med1917
17.9.2 Cleavable linker
Peptide, disulfide, and hydrazone linkers are the three categories under which the first
class of cleavable linkers falls. Low-pH sensitive, glutathione sensitive, and protease
sensitive are characteristics, of a distinct intracellular state, peculiar to tumors [52]. Be-
cause the endosomes and lysosomes of cancer cells have a low pH (4–6), acid-sensitive
hydrazone linkers can take advantage of this and undergo acid hydrolysis, releasing
the cytotoxic payload. Disulfide linkers take advantage of greater glutathione concentra-
tions in cancer cells and are more persistent in the bloodstream. Because glutathione is
linked to both tumor growth and cell survival, as well as being enhanced under condi-
tions that stress cells, such hypoxia, it is found in higher concentrations in cancer cells
[53]. A (lysosomal protease-sensitive) peptide is an additional type of cleavable linker
that is more stable than the others mentioned above. Additionally, by using mAbs to
connect to the cytotoxic agent, it allows for better control over drug release. Peptide-
based linkers are designed to be broken down by specific intracellular enzymes (pro-
teases), releasing their hazardous payload. For instance, the tumor-specific protease ca-
thepsin B identifies and cleaves a particular dipeptide bond within the tumor cells [54].
The cathepsin B-sensitive dipeptide linkage (valine-citrulline) is found in FDA-approved
Adcetris
®
. Another protease-sensitive linker, β-glucuronide, is hydrolyzed and degraded
by β-glucuronidase, a lysosomal enzyme that sele ctively releases payloads and is
overexpressed in many malignancies. Burke et al. demonstrated that β-glucuronide-
conjugated monomethyl auristatin E (MMAE), a PEGylated self-immolative linker,
had a DAR value of 8 and im proved efficacy and pharmacokinetic stability in xeno-
graft models, when compared to nonPEGylated linkers. For glucuronic acid linker-
based ADCs to be clinically improved, more study is necessary [55].
17.9.3 Noncleavable linkers
The second class of ADC linkers consists of maleimidocaproyl (mc) and noncleavable
thioether, both of which rely on the lysosomal enzymatic breakdown of ADC to release
the deadly payload, after internalizing to cancer cells [56]. For instance, a noncleavable
mc-linker was effectively used in the design of Kadcyla
®
to link maytansinoid toxin to
the HER2 Ab. Kadcyla
®
remains stable in serum for over three days due to the stable
linker. The development of novel linkers for hazardous payload conjugation at the
linker location rather than the Ab site has been facilitated by the advanced design. For
instance, Syntarga’s SpaceLink Technology is an extremely adaptable linker-based ADC.
This linker has the ability to attach to Ab and the hazardous payload in reverse. This
makes it possible to choose and optimize the payload and linker–payload combination
to produce ADCs with the highest possible therapeutic potency. Anti-HER2-duocarmycin
conjugates, which show in vivo anticancer activity with less off-target toxicity, are a
prime example of this exciting new technique. In order to provide ADC to patients
17 Molecular simulation-based technology for antibody–drug conjugates 395
https://t.me/med1917
safely and effectively for the treatment of chronic illnesses, researchers are currently
looking into a number of other cutting-edge linkers [57].
17.10 Cytotoxic payloads for ADCs
The cytotoxic payload, which is the effector component of an ADC, needs to fulfill a
number of essential criteria. To be effective, it must first possess cytotoxic efficacy in
the sub-nanomolar range. In fact, the amount of target antigens on the cell surface,
internalization and transport efficiency, and dispersion into tumor tissues all place
constraints on the ultimate payload concentrations that may be achieved within
tumor cells [58]. Secondly, in order for the payload molecule to successfully conjugate
to the antibody moiety, it must have a functional group. Lastly, under physiological
circumstances, the payload needs to be stable and soluble. ADCs that were not clini-
cally useful were those that used authorized anticancer medicines as a payload, such
as doxorubicin, but their lack of efficacy in human subjects was a contributing factor.
Considerable scientific effort was directed toward creating appropriate payloads for
ADCs as a result of the realization that ADC technology offered a chance to resurrect
extremely strong molec ules that were too poisonous to be clinically useful on their
own [59]. Another thing to keep in mind is that proteolytic enzymes can be used to
activate ADCs in tumor therapy because they are frequently overexpressed in tumor
cells and/or the stromal compartment.
The effectiveness of linker cleavage in ADCs and the subsequent release of active
payload into the cell can be impacted by changes in proteases. Auristatins and may
tannoids are two examples of strong microtubule inhibitors that are the payload of
most ADCs that are presently being used in clinical settings. Recently, the focus has
shifted to assessing DNA-interacting compounds as payloads for ADCs. But even with
ADCs bearing these compounds that have been clinically validated and show promise,
there is still a lot of interest in creating and using cytotoxic drugs with different
modes of action [60].
The uptake of ADCs and the subsequent release of active cytotoxic molecules into
the cytoplasm of tumor cells determine their efficacy. When targeting antigens are
not expressed in sufficient amounts in a tumor, the payload’s potency should be ade-
quate to eradicate the cancer cells, even at low dosages. Since ADCs are currently ad-
ministered intravenously, it is imperative that the cytotoxic payload has a prolonged
half-life in the bloodstream. In addition to these physical and chemical characteristics,
the cytotoxin’s chemical structure should permit conjugation to the linker while pre-
serving the antibody’s internalization characteristic, enhancing its anticancer effects
[61]. Due to the poor intracellular drug delivery – roughly 2% of the injected ADC dose
is expected to reach the tumor site – the drug payload in the ADC should exhibit a
high potency therapeutic index. A medication should be strong enough to destroy can-
396 Abhishek Singh et al.
https://t.me/med1917
cer cells that are dividing rapidly but not so strong as to kill healthy cells, in order to
be used in an ADC. Actually, only six to eight compounds can be employed in clinical
trials; these payloads are mostly derived from natural product sources and fall into
the following categories: (i) DNA synthesis inhibitors (calicheamicin, doxorubicin, du-
ocarmycin, and pyrrolobenzodiazepines (PBD)); (ii) topoisomerase inhibitors (SN-38
(quinoline alkaloids)). (iii) Microtubule inhibitors (DM1, DM4, MMAF, and MMAE) [62].
Therefore, in vitro sub-nanomolar IC50 (half maximal inhibitory concentration)
against tumor cell lines and a suitable functional group with sufficient solubility in
aqueous solutions for chemical conjugation with the Ab, improving the solubility of
the resulting ADC, are ideal characteristics for an ADC payload. The following list in-
cludes derivatives of auristatin, maytansinoid, calicheamicin, duocarmycin, PBD, and
amanitin that are currently being used as cytotoxic payloads.
17.10.1 Auristatin
Auristatin is an analog of auristatin, based on dolastatin 10. Due to Dolastatin 10’s
nonspecific toxicity, clinical trials were halted. MMAE and MMAF, two of its synthetic
counterparts, are presently employed in ADCs as cytotoxic payloads; however. MMAF
and MMAE are inhibitors of mitosis. Adcetris
®
is the only auristatin-based ADC that
has received FDA approval and is used to treat lymphoma and systemic anaplast ic
large cell lymphoma (sALCL). Nonetheless, overtenADCs,basedonauristatin,are
presently undergoing clinical studies (Table 17.1) [63].
Table 17.1: List of antibody–drug conjugates (ADCs) that are presently undergoing phase II or III
evaluation (ClinicalTrials.gov lists ongoing trials).
ADC Target Payload Indication(s) Sponsor References
Phase III
Depatuxizumab
mafodotin
EGFR MMAF Glioblastoma AbbVie []
Enfortumab
vedotin (ASG-
CE)
Nectin- MMAE Urothelial cancer Astellas Pharma
Global
Development
Mirvetuximab
soravtansine
Folate
receptor
alpha
DM Ovarian cancer, fallopian
tube cancer, primary
peritoneal cancer
ImmunoGen, Inc.
Polatuzumab
vedotin
CDb MMAE Diffuse large B-cell
lymphoma
Hoffman-La Roche []
17 Molecular simulation-based technology for antibody–drug conjugates 397
https://t.me/med1917
Table 17.1 (continued)
ADC Target Payload Indication(s) Sponsor References
Rovalpituzumab
tesirine
Delta-like
protein
PBD Small cell lung cancer AbbVie
Sacituzumab
govitecan
TROP-
receptor
SN- Triple-negative breast
cancer
Immunomedics,
Inc.
Trastuzumab
deruxtecan
HER DXd Metastatic breast cancer Daiichi Sankyo, Inc.
[vic]-
trastuzumab
duocarmazine
HER DUBA Metastatic breast cancer Synthon
Biopharmaceuticals
BV
Phase II
AGS-CF ENPP MMAF Renal cell carcinoma Astellas Pharma
Global
Development
[]
Anetumab
ravtansine
Mesothelin DM Ovarian cancer, Pancreatic
cancer, non-small cell lung
cancer
National Cancer
Institute
BMS- Mesothelin Not
disclosed
Mesothelioma, non-small
cell lung cancer, ovarian
cancer, pancreatic cancer,
gastric cancer
Bristol-Myers
Squibb
[]
Brentuximab
vedotin
(ADCETRIS
®
)
CD MMAE Anaplastic large cell
lymphoma, Hodgkin’s
lymphoma, non-Hodgkin’s
lymphoma, T-cell
lymphoma
Seattle Genetics
Depatuxizumab
mafodotin
EGFR MMAF Pediatric high-grade
gliomas
AbbVie
Enfortumab
vedotin (ASG-
CE)
Nectin- MMAE Urothelial bladder cancer Astellas Pharma
Global
Development
[]
GSK B-cell
maturation
antigen
MMAF Multiple myeloma GlaxoSmithKline
Lorvotuzumab
mertansine
CD DM Pediatric sarcomas Children’s Oncology
Group
Naratuximab
emtansine
CD DM Non-Hodgkin’s lymphoma Debiopharm
International SA
[]
398 Abhishek Singh et al.
https://t.me/med1917
17.10.2 Maytansionids
The function of maytansinoids (DMs), which are thiol derivatives of maytansines, is
comparable to that of vinca alkaloids. Mature microtubule formation is inhibited by
maytansines, which attach to the growing microtubule’s “plus” end and hinder tubu-
lin dimer polymerization. DM1 or DM4)-conjugated ADCs, on the other hand, have the
ability to deliver the payload to cancer cells selectively, which raises the therapeutic
index [71]. Clinical trials are presently being conducted on certain ADCs, based on
maytansinoid, for hematological and solid maligna ncies. Among these, the FDA ap-
proved trastuzumab-DM1 (Kadcyla
®
), a maytansinoid-linked HER-2-targeting ADC, for
treatment against metastatic breast cancer that is HER-2 positive.
17.10.3 Calicheamicin
ADCs employ the powerful DNA-targeting chemical calendricin as a poisonous pay-
load. DNA replication is inhibited by calicheamicin when it identifies the minor
groove of the TCCTAGGA sequence [43]. An acid-cleavable hydrazone linker is present
in Mylotarg
®
, a calicheamicin γ1-anti-CD33 conjugate. Ten years after Mylotrag
®
was
first approved, the medicine was taken off the market due to side effects that included
calicheamicin that released prematurely, low drug-to-absorbent conversion efficiency,
exchange of the Fab arm with serum Ab, and unintended binding of ADC to CD33-
Table 17.1 (continued)
ADC Target Payload Indication(s) Sponsor References
Rovalpituzumab
tesirine
Delta-like
protein
PBD Small cell lung cancer Stemcentrx
SAR CA DM Triple-negative breast
cancer
Sanofi
Telisotuzumab
vedotin
c-MET MMAE Squamous cell lung
carcinoma
Southwest
Oncology Group
Trastuzumab
deruxtecan
HER DXd Breast cancer, colorectal
cancer, gastric and GE
junction cancer, Non-small
cell lung cancer
Daiichi Sankyo, Inc. []
Trastuzumab
emtansine
HER DM Metastatic colorectal
cancer
Fondazione del
Piemonte per
l’Oncologia
(researcher)
17 Molecular simulation-based technology for antibody–drug conjugates 399
https://t.me/med1917
positive liver cells [72]. ADC CMC-544, which targets CD22 (IgG4) and is connected to
calicheamicin, has been investigated in several clinical studies for various hematolog-
ical cancers, including non-Hodgkin’s lymphoma (NHL) and all.
17.10.4 Duocarmycin
The IC50 range for the powerful antitumor antibiotic duocarmycin is 40–100 pM. It
alkylates adenine bases in the minor groove of DNA, which is its target. Duocarmycin
synthetic analogs, like CC1065, are expected to be a powerful payload for ADCs; BMS-
936561 (MDX-1203), for example, is presently undergoing a phase I clinical trial. When
applied to drug-resistant cell lines, such as DLD-1 and HCT-15, CC1065-conjugated ADCs
have demonstrated efficient anticancer effects in vivo at lower dosages [73].
17.10.5 Amatoxin
A cyclic peptide known as amatoxin binds to RNA polymerase II, inhibiting DNA tran-
scription and ultimately causing programmed cell death. α-amanitin ADC is associated
with ChiHEA125-Ama, an anti-EpCAM.
17.11 Other ADC payloads
ADC development can benefit greatly from the use of many other cytotoxic payloads,
such as PBD derivatives and centanamycin (indole carboxamide). By binding to DNA
double strands and either intercalating or alkylating the DNA, these chemicals pre-
vent DNA replication.
Phase I clinical studies are presently underway for the PBD-containing ADCs,
SGN-CD33A and SGN-CD70A (Table 17.1). PBDs are created spontaneous ly and enter
tumor cells by intercalating certain DNA sequences. By preventing cancer cells from
proliferating, tumor growth may be inhibited without causing structural changes to
the DNA helix, which helps prevent the emergence of drug resistance [74].
17.11.1 Doxorubicin
Doxorubicin prevents DNA synthesis by intercalating into DNA. For instance, phase I/
II clinical trials have been conducted on milatuz umab-conjug ated doxorubicin ADC
(IMMU-110) for the treatment of CD74-positive relapsed multiple myelomas.
400 Abhishek Singh et al.
https://t.me/med1917
The main difficulty in creating a novel cytotoxic medication is that it must have a
high therapeutic index value [75]. This means that a small dosage of the medication
would be sufficient to eradicate the tumor cells and minimize side effects.
17.12 Mechanism of action
ADCs utilize the specificity of antibodies to bind to antigens on cancer cells in a tar-
geted manner. After binding, the ADC internalizes and releases its cytotoxic payload,
which causes the cancer cell to die. The goal of this focused strategy is to lessen the
negative effects of traditional chemotherapy while protecting healthy cells [76].
17.12.1 Target-specific binding
The exact identification and binding of mAbs to certain antigens expressed on the sur-
face of cancer c ells is the first stage in the ADC process. ADC selectivity is based on
this tailored binding.
17.12.2 Monoclonal antibody recognition
The process of creating ADCs starts with the engineering or selection of mAbs that are
able to identify and attach to certain antigens that are overexpressed on the surface
of cancer cells. Because of its specialized recognition, the ADC is able to distinguish
cancerous cells from healthy tissue and focus on them specifically [77].
17.12.3 Antigen selection
The selection of antigens is well thought out. Cancer cells should have high concentra-
tions of these antigens, which makes them perfect targets for the A DC. Maintaining
this specificity is essential to reduce off-target impacts.
17.12.4 Selective binding
The cytotoxic payload is delivered to specific cancer cell antigens with the help of a
complex that is formed when the mAbs bind to those antigens selectively. The next
steps in ADC action are set in motion by this exact identification [78].
17 Molecular simulation-based technology for antibody–drug conjugates 401
https://t.me/med1917
17.12.5 Intracellular payload release
Following binding to a specific target, the ADC–antigen complex internalizes itself in-
side the cancer cell, releasing its payload intracellularly. This procedure guarantees
that the targeted recipient receives the cytotoxic payload only.
17.12.6 Endocytosis
Endocytosis is a biological process by which the cancer cell engulfs the ADC–antigen
complex by producing vesicles, facilitates internalization. The ADC is protected from
the outside world by this internalization, which also gets it ready for the next steps of
action [79].
17.12.7 Intracellular trafficking
The cancer cell engages in intracell ular trafficking of the internalized vesicles that
carry the ADC–antigen complex. This fluid motion is an essential preamble to the last
actions that result in payload discharge.
17.12.8 Lysosomal degradation
Eventually, the vesicles unite with the cellular organelles called lysosomes, which are
in charge of destruction. This fusion sets up the ADC payload’s release into the lyso-
somal compartment, which in turn releases it into the cytoplasm [80].
17.13 Payload release
The linker that connects the payload to the antibody is made easier to cleave by the
lysosomes’ acidic and enzymatic conditions. The cytotoxic payload is released during
this cleavage and enters the cancer cell’s cytoplasm to begin acting toxically.
17.13.1 Payload-mediated cytotoxicity
Now that the cytotoxic payload has entered the cytoplasm of the cancer cell, it must
execute its cytotoxic effects to cause cell death in the last stage [81].
402 Abhishek Singh et al.
https://t.me/med1917
Соседние файлы в папке Библиотека им академика М.И. Перельмана