J. Med. Chem. - University of Toledo

Report
“How the Evolution of Medicinal Chemistry and an
Academic-based Drug Discovery Center led to
SEARMs: Novel ‘Selective Estrogen and Androgen
Receptor Modulators’ from Soybean”
Distinguished University Professor Lecture
Presented on January 29, 2015 by Paul Erhardt, PhD
UT DUP and Director of the Center for Drug Design and
Development (CD3)
[email protected]
1
Outline
• Center for Drug Design (CDD)
• Center for Drug Design and Development (CD3)
• CD3 Project-associated Small Molecule Drug Leads
• ‘SEARMs’ from Soybeans
• Today’s Pharmaceutical Enterprise
2
UT’s Center for Drug Design (CDD)
• Late 1980s: Drs. Richard Hudson and Wayne Hoss with
administrative support from College of Pharmacy Dean Norm
Billups; UT Board-approved; First Director Dr. Graham Durant
(Cimetidine [1]).
• A new venture launched during turbulent times for medicinal
chemistry (Med Chem) and WAY AHEAD OF ITS TIME.
• Med Chem history [2,3]: ‘Born’ from the fertile mix of ancient folk
medicine and early natural product chemistry more than 100
years ago, it incubated as part of the mix with ‘pharmaceutical
chemistry’ for many years before becoming formally recognized as
a distinct academic discipline just a little more than 75 years ago
within U.S. colleges of pharmacy
3
Med Chem History cont.
→ Understanding the relationships between chemical structure and
biological activity (SAR) at the fundamental level of physical organic
properties and molecular conformation soon became the hallmark of
basic Med Chem research
- Distinguishing it from natural products which had instead
moved its focus toward understanding phytochemistry etc.
- And (because this basic knowledge could be applied to
drug design) resulted in Med Chem’s quick adoption by the
pharmaceutical industry for its continued maturation
→ Med Chem’s ‘adolescent heyday’ began about 50 years ago (early60’s) when a growing knowledge about pharmacological mechanisms
led to the view that rational drug design (RDD) guided by biological
information would result in numerous new therapeutics; However,
4
Med Chem’s History cont.
→ By the mid-80’s it had become clear that RDD had fallen way short
of the hype; If anything the trend in producing new chemical entities
(NCE’s [4]) was beginning to slope downward.
Adding insult to this injury: after it had only a small number
of clinical success stories to relay “Med Chem’s preconceived notions
about what a new drug ought to look like” took on negative rather
than positive connotations.
→ By the late-80’s the pressure to find new drugs was leading to
high-throughput testing of compound libraries preferably having high
molecular diversity and undertaken in a random manner; And, alas,
amid this newest craze/hype Med Chem itself had survived its
adolescence only to have fallen into an ‘identity crisis;’ The only good
news was that the fuse had also been lit for the biotechnology
explosion.
5
Meanwhile
• After a seemingly successful start that had identified an
interesting compound from Dr. Bill Messer’s lab to
potentially treat Alzheimer’s disease (CDD-0102A, [5]), Dr.
Durant soon returned to industry and, despite continued
efforts internally, within just a few years (early 90’s) the
CDD’s initial momentum was essentially gone; A new
Director having industry savvy with a successful track record
of drug discovery was again deemed to be necessary.
→ In 1994 PWE accepted the ‘two-hat’ position of a tenured
faculty and new Director for the stagnating drug discovery
center within UT
6
Center for Drug Design and Development (CD3)
• First few years were rough: Although not yet ‘generationally diverse,’
PWE was ‘well-seasoned’ and no longer qualified for ‘young
investigator’ awards even though a total rookie within academe and the
demanding rigors of grant-writing; But
• Turning-point occurred during the third year: Invited membership on an
NIH Study Section Special Panel for Drug Development; Susan G Komen
National Research Award followed by the first of a series of DOD Grants.
• By mid-2000 the CD3 was operating at a level of ca. $ 1 M (plus) / year
from extramural funding using a mixed financial portfolio: Federal USDA
and continued DOD stream, and the State’s OSC all being representative
of government $; Collaboration with the CCF’s GCIC representing
significant public / foundation $; and, SRAs with Parke-Davis / Pfizer, as
well as numerous small biotech company SRA & SBIRs representing the
private sector where both $ and key equipment was garnered (e.g. LCMS/MS, metabolism cages).
7
CD3 cont.
• Today’s CD3 is a core translational research center operating out
of the CPPS; but now also in close ties with the CMLS.
Structure/budget-wise it operates like a Dept while receiving no $
from UT. Instead, it continues to rely solely on extramural funding
to pursue its long-standing two-fold mission, one pertaining to
research and the other pertaining to education. Respectively,
these are:
(1) Assist in the design and development of potential small molecule
diagnostics/biomarkers, therapeutics or disease preventative
agents with the goal of facilitating their translation into clinical
applications
- Although focusing upon UT technologies, collaborations
and contracts encompass the global health care research
enterprise.
8
CD3 Mission cont.
(2) Provide unique opportunities for students to enhance their
educational experience by conducting both basic and
applied research while participating as members of highly
interdisciplinary teams
- Opportunities range from a “Shadow Program” for
high school and early undergraduate students, more
formal / credit lab courses and associated
Department degree tracks for undergrads and
graduate students, postdoctoral experiences, and
visiting scientist and sabbatical collaborations.
9
“PEOPLE, Money and Things Getting Done”
• Extramural dollars are used to support a cadre of investigators and
graduate students, at its peak including more than 25 active participants,
who operate as a ‘cohesive team’ to tackle cutting-edge research
projects.
• The CD3’s team includes a critical mass of interdisciplinary investigators
that provides a high degree of expertise in 7 core areas relevant to drug
design and development: (1) Computational chem & molecular
modeling/docking studies; (2) Synthetic Med Chem “hit follow-up” and
“early ADMET” optimization studies; (3) Frontline screening and biol.
testing using biochem. and cell culture assays in 96-well, semiautomated format; (4) Anal. and bioanal. chem using ‘validated GLPcompliant’ assay methods on HPLC and LC-MS/MS instrumentation; (5)
Non-GMP scale-up and process chem optimization; (6) Secondary
pharmacological and advanced ADMET-PK studies in vitro and in vivo;
and, (7) IP and patent protection strategies and implementation.
10
CD3 People cont.
• Some investigators have been with the CD3 for 10 or more years and
have progressed from entry-level postdocs to full Research Professors
- Drs. Peter Nagy and Jeff Sarver (JGS)
- Dr. Jill Trendel (JAT).
∙
While technical expertise has been emphasized, the CD3’s administrative
components/activities have been minimized; The CD3’s ‘Administrative
Team’ consists of PWE, JGS & JAT.
∙ STUDENTS represent an unending flow of bright and eager new
participants who can be a source of creative ideas while exhibiting unending
energy coupled to unbridled enthusiasm; The camaraderie that flourishes
among interdisciplinary scientists having different levels of professional
maturity and rich international backgrounds has often become synergistic
during ‘work’ and ‘play.’
11
CD3 Team 2007 at ‘Work’
12
CD3’s Award Winning SGK Race Team 2012 [16]
13
CD3 Team 2013 at ‘Play’
14
Interesting CD3 Projects (Drug Leads)
15
Pgp: A Glimpse of the Enemy; But There’s
Another Even Bigger Foe
16
Molecular Probes “Going for the Gold”
17
Directing Drug Distribution
18
CD3 and Collaborator Derived Projects
19
CD3 Collaborative Projects
20
CD3 Collaborative Projects cont.
21
Methuosis Makes the Cover of “Rolling Stone”
- well at least the equivalent for medicinal chemists: ACS Med.
Chem. Letters and IUPAC Chem. International [24-26]
Drug design and development is the focus of Paul Erhardt’s
article on page 8, Director of the Center for Drug Design and
Development (CD3) within the University of Toledo. The
cover of this issue [Chemistry International, 36, No. 6] depicts
a non-apoptotic form of cell death called “methuosis”
recently identified and coined by Dr. William Maltese.
Maltese’s novel cell biology discovery has led to a strong
collaborative effort with the CD3 providing synthetic (Dr.
Chris Trabbic) and bioanalytical (Dr. Jeff Sarver) chemistry
expertise directed toward identifying small molecule agents
capable of selectively inducing this phenomena within
cancer cells [M. Robinson, et al. J. Med. Chem., 55, 2012, pp.
1940-1956 and C. Trabbic, et al. Med. Chem. Lett., 5, 2014, pp.
73-77.] A variation of this illustration was highlighted
previously on the cover of ACS Med Chem Lett Vol. 5 No. 1,
2014 as an accompaniment for the Trabbic et al. technical
article cited above. In both instances the graphic was
prepared by Roy Schneider, Medical and Biological
Illustrator at the University of Toledo.
22
SEARMs from Soybeans
x
x
● Late 1994: PWE sets-up shop;
CDD → CD3 needs bioanal. equip.;
$ is tough to come by but was able
to raise an HPLC from the dead
● Early 1996: Rick Vierling, PhD
(Purdue Agronomy /ICIA) needs
HPLC fingerprints of hybrid soy
cultivars [30]
● PWE learns two things: Phytochemistry is as fascinating as human
chemistry, particularly the phytoalexins [30]; and, There’s a whole
heck of a lot more $ in potato chips
than drugs
23
Meanwhile: A Marriage Made on Earth (if Not
in Heaven) Would Soon Occur
• HTS within the pharmaceutical industry to identify “hits” if not “lead
compounds” had created a huge appetite for compound libraries,
molecular diversity being touted as an attribute → HTS + ‘Combinatorial
Chemistry’ were quickly wed
• Liking the notion of compound libraries and wanting to go with the flow,
but instead as individually pure and specific probes for biology and SAR
PWE asked two questions:
- How did we historically pursue diverse molecular leads obtained
from natural sources; and
- How might that be done within the context of today’s rapidly
evolving technologies?
→ Historically by making about 100 plus derivatives/analogs of the
initial NP; but perhaps now by . . .
24
The Birth of a Proposal and Some Big Time
Funding for the CD3
•
•
•
Stressed soybeans → Novel phytoalexins via aggressive phytochemical
pathways; so let’s turn that on and then also provide novel feedstock for the
plant’s ‘reved-up’ biochem. → Might this become a “directed library”
derived from the promising initial phytoalexin-type NP or perhaps a library
having even more unique molecular diversity to test (“Combinatorial
Phytochemistry”)?
Thanks to an alert from UT’s Frank Calzonetti, my proposal was submitted to
the USDA in response to an RFA to enhance the components within U.S.
legume crops in order to continue to be competitive across the world’s
agricultural market, soybeans alone constituting a multi-billion $ product
that makes blockbuster drug sales ‘pale in comparison’
USDA SRRS (Steve Boue & Ed Cleveland, PhDs) collaborating with Tulane
(Matt Burow & John McLachlan, PhDs) and Xavier (Tom Wiese, PhD)
Universities all located in New Orleans already had identified an interesting
phytoalexin from stressed soybean seeds and were receiving $ to follow-up
but lacked a ‘chemistry partner’ → Could and would we work together?
25
Where We Were and Where We Wanted to Go:
I. Soy’s Normal Phytochemistry
26
II. Soy’s Stressed Phytoalexins
27
Soy’s Stressed Phytoalexins cont.
28
III. Glyceollins Isolation and Activity
• Fungal-stressed soy seeds → Methanolic extraction / Chromatographic
separation into GLYs I, II and III but further separation extremely tedious
→ ca. 0.005% of dry seeds’ mass with GLY I being the major constituent;
Analytical standard of natural GLY I in-hand
• Cell culture assay of GLY mix suggests promising anticancer activity in hBC
panel; Anti-estrogenic activity confirmed via extensive analysis of
pathway and genetic markers; GLY I also appears to be the most
predominantly active member
• Immediate needs: Confirmation of activity in an in vivo model ← CD3 to
provide synthetic access to all three GLYs, particularly multigram scale-up
of GLY I
29
Synthetic Approaches to the GLYs
30
Summary of Synthetic Efforts
•
•
•
•
•
•
•
•
Total Synthesis of Xanthohumol. R. Khupse and P. Erhardt. J. Nat. Products, 70, 1507-1509
(2007).
Practical Synthesis of Lespedezol A1. R. Khupse and P. Erhardt. J. Nat. Products, 71, 275-277
(2008).
Total Syntheses of Racemic, Natural (-) and Unnatural (+) Glyceollin I. R. Khupse and P.
Erhardt. Org. Lett., 10, 5007-5010 (2008).
Total Syntheses of Racemic and Natural Glycinol. A. Luniwal, R. Khupse, M. Reese, L. Fang
and P. Erhardt. J. Nat. Products, 72, 2072-2075 (2009).
Total Syntheses of (±) Vestitol and Bolusanthin III Using a Wittig Strategy. A. Luniwal and P.
Erhardt. SYNLETT, 11, 1605-1607 (2011).
Biomimetic Synthesis and Antiproliferative Properties of Racemic, Natural (-) and Unnatural
(+) Glyceollin I. R. Khupse, J. Sarver, J. Trendel, N. Ellis, M. Reese, T. Wiese, S. Boue, M.
Burrow, T. Cleveland, D. Bhatnagar and P. Erhardt. J. Med. Chem., 54, 3506-3523 (2011).
Multigram Synthesis of Glyceollin I. A. Luniwal, R. Khupse, M. Reese, J. Liu, M. El-Dakdouki,
N. Malik, L. Fang and P. Erhardt. Org. Process Res. Dev., 15, 1149-1162 (2011).
Synthesis of 6a-Hydroxypterocarpans via Intramolecular Benzoin Condensation. N. Malik and
P. Erhardt . Tet. Lett., 54, 4121-4124 (2013).
31
Scaled-up Synthesis of GLY I via the Wittig Strategy
32
Stereochemistry: ‘cis’ (S,S)
20
10
-10
Δε
O
O
AU
-20
OH
0.040
0.040
0.035
0.035
0.030
0.030
0.025
0.025
AU
32
9
29
9
26
9
23
9
0
0.020
0.020
0.015
0.015
0.010
0.010
0.005
0.005
-30
O
OH
-40
0.000
0.000
(-) Glyceollin I
0.00
5.00
10.00
5.00
10.00
15.00
20.00
25.00
30.00
35.00
Minutes
40.00
45.00
50.00
55.00
60.00
65.00
0.00
70.00
5.00
10.00
15.00
20.00
25.00
30.00
35.00
Minutes
40.00
45.00
50.00
55.00
60.00
65.00
70.00
5.00
10.00
15.00
20.00
25.00
30.00
35.00
Minutes
40.00
45.00
50.00
55.00
60.00
65.00
70.00
-50
0.12
-60
Wavelength (nm )
0.10
AU
0.08
0.06
60
0.04
0.02
50
0.00
0.00
O
O
15.00
20.00
25.00
30.00
35.00
Minutes
40.00
45.00
50.00
55.00
60.00
65.00
70.00
40
OH
O
0.050
0.050
0.040
0.040
0.030
0.030
30
10
AU
Δε
20
AU
(+) Glyceollin I
OH
0.020
0.020
0.010
0.010
0.000
0.00
0.000
5.00
10.00
15.00
20.00
25.00
30.00
35.00
Minutes
40.00
45.00
50.00
55.00
60.00
65.00
70.00
0.00
32
9
29
9
26
9
23
9
0
-10
Wavelength(nm)
-20
33
Synthesis of Glyceollin I: Disadvantages
34
35
Entry
Catalyst
Base
Solvent
Time
1
C1
DBU
THF
5h
2
C1
KOtBu
THF
3h
3
C1
NEt3
THF
12 h
4
C2
NEt3
Toluene
12 h
Products
18, 18a ,18b
91%
85%
<5%
78%
<5%
83%
42
37
Malik, N.; Erhardt, P. Tetrahedron Lett. 2013, 54, 4121
Highlights• 10 step total synthesis
• 20% overall yield of (±)-Glycinol
• Two column purifications
• Eliminated use of OsO4
• Intramolecular Benzoin Cyclization
• Epoxide mediated final ring closure
38
Promising In Vivo Data [31,32]
Treatment = MCF-7 tumor implant;
Agents given i.p. every 2 days
Treatment = Glucose po to pre-diabetic rats (T = 0)
GLY po 1 hr in advance
(GLY caused uptake by adipocytes comparable to insulin)
39
Two Directions to Pursue
• But the Congressional dollars were gone: New
Orleans joins forces with NuMe, Ltd. to pursue
fortified foods for potential treatment of diabetes;
UT’s CD3 remains more interested in potential
anticancer activity and GLY I’s unusual biological
profile in that regard
• Two drivers contributed to the CD3’s interest: PWE’s
proposal to the Ohio Soybean Council was still
providing some $; and, The CD3’s ‘a bit different’ cell
culture data remained highly intriguing
40
“One Man’s Garbage, Another Man’s Gold”
(CD3 Soy Harvest Project Team 2008)
41
Intriguing Data Indeed
Our previous human cell culture studies had employed: ER+ MCF7 BC, ERMCF12A immortalized normal breast epithelial, ER- NCI/ADR-RES OC, AR+
LNCaP PC, AR- PC3 PC and AR- DU145 PC cells; To study GLY I as each of its
enantiomers and as the racemate; While using fulvestrant, 4-OH-tamoxifen
and genistein as pure anti-estrogenic, SERM, and mixed agonist/antagonist
standards, respectively. Dose response curves were recorded under low,
medium and high estradiol (E2) levels for the female cell lines and under
routine E2 and dihydrotestosterone levels for the prostate cell lines
●
GLY I showed highest GI activity in the MCF7 culture but also remained
active in all of the other female cell lines wherein the standards did not. It
was also unaffected by changes in E2 levels. While all standards had some
activity in all of the prostate cell lines, GLY I demonstrated a significantly
higher effect with a notable preference for the LNCap.
●
42
Might We Be Looking at a Dual ER and AR Ligand?
• Dogma suggests otherwise; Closest examples exhibit uM vs. nM potency.
CoAc/
CoRe
HSP
L + ER
(L-ER)2
Cell Effects
ERE et al
DNA
ER Express.
ER Degrad.
• Theoretically feasible? Computational studies seemed warranted first.
Then ER and AR functional receptor bioassays could be utilized to lesson
the inherent complexity of the cell-based assessments.
43
Considering GLY I Itself
•
●
•
•
Ab Initio Study of Hydrogen-bond Formation Between Cyclic Ethers and Selected Amino Acid Side Chains.
P.I. Nagy and P. Erhardt. J. Phys. Chem. A, 110, 13923-13932 (2006).
Ab Initio Study of Hydrogen-Bond Formation Between Aliphatic and Phenolic Hydroxy Groups and Selected
Amino Acid Side Chains. P. Nagy and P. Erhardt. J. Physical Chem. A, 112, 4342-4350 (2008).
Theoretical Studies of Salt-bridge Formation by Amino Acid Side-chains in Low and Medium Polarity
Environments. P. Nagy and P. Erhardt. J. Physical Chem. B, 114, 16436-16442 (2010).
Ab initio = MP2/6-31+G* and MP2/aug-cc-pvtz
44
GLY I Computational Studies cont.
Straight (Arced)
Bent
Bent favored by -0.5 Kcal (P. Nagy unpublished studies)
45
X-Ray Structures of hERs and AR Selected
from the pdb for Docking Studies
•
More than 50 structures available/chose prototypical standards. Surflex docking program run
on MacOS workstation with SYBYL software/visual inspections using PyMOL. Total of 540
examinations performed on the accumulated modeling data (THANKS! R. Jetson and N.
Malik). Docking scores shown above are for just the highest ‘total score’.
46
ERα Agonist /Antagonist Models
Left: GLY I (Green) and E2 (Light Blue) binding with agonist model 1GWR.
Middle: GLY I and raloxifene (RLX) binding with antagonist model 1ERR.
Right: Structure of RLX.
47
ERβ Antagonist Model
GLY I (Green) and (R,R)-cis-diethyltetrahydro-2,8-chyrsenediol (DTC; Pink;
structure on right) binding with antagonist model 1L2J.
48
AR Agonist / Antagonist Models
Left: GLY I (Green) and DHT (Light Blue) binding with agonist model 2am9.
Middle: GLY I and bicalutamide (BCL) binding with antagonist model 1Z95.
Right: Structure of BCL. Arrow suggests 90° rotation of phenyl-ring.
49
Summary of Molecular Modeling Studies
•
GLY I can adopt favorable H-bonds at either end of the ER and AR LBDs.
•
However, they may be less important than GLY I’s ability to ‘flip, bend and spin’ so as to simulate
the size and shape of the various hormones and antagonists known to be active at either ER or
AR systems. It follows that these types of ‘good steric fits’ and favorable Van der Waals
interactions within the LBDs may be largely driven by GLY I’s distinct 6a-hydroxypterocarpan
scaffold accompanied by the display of its remaining structural elements; The 6a-hydroxy group
itself, however, seems to contribute only modestly toward binding.
•
Similar interactions with both ER agonist and antagonist models suggests that GLY could be a
partial agonist depending upon E2 concentration → perhaps explaining some of the ambiguity
expressed by different labs with regard to cell culture data.
•
The remarkable observation of GLY I’s bend so as to so closely follow the binding mode adopted
by bicalutamide seems like more than coincidence and suggests that it could act like an AR
antagonist.
•
Importantly, molecular modeling studies do not rule out the possibility that GLY I may be able to
interact with the LGBs of both ER and AR systems and, instead, suggest that it may do so in
binding paradigms that resemble those that are well established for prototypical standard agents.
50
Biochemical Assessment
•
LanthaScreen TR-FRET Coactivator kits for functional biochemical assays of ERα,
ERβ and AR were purchased from Invitrogen. Black, low-volume 384-well plates
were read by a Molecular Devices SpectralMax MF microplate reader with
excitation at 332 nm and emissions of 488 and 520 nm; TR-FRET ratio calculated as
the 520/488 readings.
•
Natural (-) G1 and unnatural (+) G1 were tested along with agonist standards E2
and DHT, and antagonist standards RLX, 4-hydroxytamoxifen (4HT; SERM) and BCL,
as well as DMSO vehicle controls, on all plates. N = 4 for each of the 10
concentrations tested for every agent. N = 12 for negative controls (vehicle only)
and positive controls used for calculating normalized activity: ER using 1 μM E2 in
agonist mode and 1 μM 4HT in antagonist mode; AR using 1 μM DHT in agonist
tests and 40 μM BCL for antagonist tests.
•
Data was normalized by comparing the TR-FRET ratio to the average pos. control
ratio (100% normalized activity) and average neg. control ratio (0% normalized
activity). Results are presented as the av. ± sem. Stat. differences (p < 0.05) were
determined by ANOVA with Tukey post-hoc analysis using SYSTAT 12 software.
51
Agent Condition
20
100 µM G1(-)
40 µM BCL
+*
* *+ * *
100 µM G1(+)
Agent Condition
1 µM RLX
1 µM 4HT
* *
1 µM DHT
0
+
1000 nM E2
*
+
100 nM E2
+*
ER
10 nM E2
+*
1 nM E2
60
0.1 nM E2
80
Normalized Agonist Activity (%)
+
Vehicle
* +* * *
100 µM G1(+)
20
100 µM G1(-)
40 µM BCL
1 µM RLX
1 µM 4HT
* *
1 µM DHT
+
+
1000 nM E2
ER
100 nM E2
100
10 nM E2
40
1 nM E2
0.1 nM E2
0
Vehicle
Normalized Agonist Activity (%)
ER Agonist Assays
100
+
80
60
40
*+
*
52
Agent Condition
40
+*
100 µM G1(+)
0
*+
100 µM G1(-)
20
40 µM BCL
*
100
1 µM RLX
*+
ER
1 µM 4HT
60
1 µM DHT
80
Normalized Antagonist Activity (%)
+
Vehicle
*+
*+
100 µM G1(+)
40
100 µM G1(-)
20
40 µM BCL
100
+
1 µM RLX
ER
1 µM 4HT
*
1 µM DHT
0
Vehicle
Normalized Antagonist Activity (%)
ER Antagonist Assays
+
*+
80
60
*+
+*
*
Agent Condition
53
Agent Condition
*
0
*
*
+
100 µM G1(+)
20
40
+
100 µM G1(-)
+*
AR
40 µM BCL
60
1 µM RLX
+*
1 µM 4HT
+*
1 µM E2
100
Normalized Antagonist Activity (%)
+
Vehicle
*
100 µM G1(+)
*
100 µM G1(-)
+*
40 µM BCL
*
1 µM RLX
* *
1 µM 4HT
+*
1 µM E2
AR
1000 nM DHT
100 nM DHT
80
10 nM DHT
40
1 nM DHT
0.1 nM DHT
0
Vehicle
Normalized Agonist Activity (%)
AR Agonist and Antagonist Assays
100
+
80
60
*+
20
*
Agent Condition
54
Summary of Biochemical Studies
•
•
•
•
•
Underscoring the historical demarcation between ER and AR ligands, the AR
standards DHT and BCL had comparably little effect on the ERs while the ER
standards E2, 4HT and RLX had comparably little effect on the AR.
Both of the GLY I enantiomers demonstrated weak agonist effects at 100 μM on
both ERs, the natural form being about twice the potency of the unnatural form.
Their effects as antagonists was more pronounced although still modest; and here
the unnatural form was about twice the potency of the natural form.
These data suggest that GLY I is a weak partial agonist at the ERs and can quickly
serve as an antagonist depending upon how the receptors are being driven by
their agonist natural hormone ligand concentrations. “This complicated pattern of
activity may explain some of the ambiguous behavior seen across the different cell
culture studies by different investigators.”
Neither of the GLY I enantiomers showed agonist effects on AR but were very
pronounced inhibitors in the antagonist model with activities were similar to the
standard BCL (100 vs. 40 μM).
These data suggest that while GLY I may be slightly less potent than BCL, it is a
more specific inhibitor of AR.
55
Overall Summary
•
•
•
GLY I appears to interact significantly with both the ER and AR LBDs at the same
concentration. Importantly, this concentration is similar to that found to be
relevant for cell-based action reported by several different investigators. This
unique dual action within a single molecule contrasts long-standing dogma
pertaining to the behavior of ligands for these classical hormone pathways.
The composite of SAR already gathered within this field suggests that GLY I’s
distinct molecular structure can serve as a ‘privileged scaffold’ [33] for analogs
having either SERM [34,35], SARM [36,37]or a combination of these two profiles.
By analogy to the former two, we are calling this novel pharmacological class of
dual agents “SEARMs.”
The possible benefits of having various ratios of this dual action simultaneously
operative across different tissues for the potential treatment of hormone
responsive cancers such as breast and prostate remain to be assessed clinically.
Toward such an end, Med Chem can play a critical role by providing key probes for
preclinical examination within in vivo animal models.
56
Acknowledgements for the Soy Studies
Ohio Soybean Council
College of Pharmacy and Pharmaceutical Sciences
Department of Medicinal and Biological Chemistry
Center for Drug Design
and Development
57
Today’s Pharmaceutical Enterprise [26]
•
•
The marriage of HTS and combinatorial chemistry has not delivered an increase in the
new drug progeny (NCEs) that had been hoped (hyped) for. To no one’s surprise this
venture has proven to be inefficient and costly; Actually both becoming much more so
than anticipated.
The accompanying flood of innovation created by the downpour of biotechnology has
become particularly entwined with the public sector’s scene and has been driving
things there for the last 20 years, some good and some not so good: NIH commits to
identifying the human genome (no impact on drug discovery - so much for that hype)
→ NIH funds directed toward proteomics and molecular biology to discern genome’s
associated function and possible relationships to pathophysiology (plethora of drug
targets/which ones are meritorious, i.e. “drugable”) → NIH establishes HTS centers
within several academic sites across the US to identify lead molecules to help address
the latter (any promising clinical testing successes to date?/now appears to be wounddown [‘consolidated’] by ca. 50%) → NIH follows-up with compound libraries for use
by request with emphasis on enhanced academic involvement on more of a lab-to-lab
basis rather than through a ‘centralizing/compartmentalizing’ process; Same for the
provision of core capabilities at academic sites to conduct drug development activities
(impact too early to assess - but look where this is heading!) → Most recently the NIH
has established the National Center for Advancing Translational Sciences (NCATS) to
foster interdisciplinary efforts toward drug discovery by “breaking the invisible barriers
of program boxes and to think as one cohesive team” [38].
58
Today’s Pharma cont.
•
•
•
•
Within the private sector the production rate of NCEs has not attained the longsought higher momentum.
Alternatively, the last 15 years has instead seen an enormous rise in costs for R&D
resulting largely from gradually increased demands by the US FDA for increased
safety testing. These financial challenges have additionally been coupled with an
increasingly disenchanted consumer and a political-economic system that affords
insurance companies greater latitude for what they will or will not pay.
PWE: (1) HTS/combinatorial chemistry has not been conducive to enhancing a
much needed knowledge base to accompany the evolving process and steps of
drug discovery - after following one-hype-after-another, attrition still runs at
nearly 90% during clinical testing for late stage ‘drug wannabes’ [3] actually
moving forward to achieve a ‘market launch’ (NCE); and, (2) ADMET issues tend to
be avoided by over-reliance upon ‘rules’ and use of less than definitive screening
protocols rather than individually studied and overcome via an academic approach
on a case by case basis.
Biotech companies have proliferated and moved an incredible amount of early
stage research forward; but VCs use a similar 1 out of 10 ratio for an expected
return on their investments.
59
In Response
•
•
•
•
Both the public and now the private sectors have continued to turn more and
more toward academe to help fix the broken pipeline of NCEs within the US.
In response, the last five years has seen a flurry of drug discovery initiatives started
within academic settings, the most recent tally of such now being ca. 80 [39] and
up from maybe just 5 or so about 20 years ago. With some NIH $ behind it, the
newly formed ‘Academic Drug Discovery Consortium’ intends to “bring together
the growing number of university-led drug discovery centers and programs” [40].
Thus, the CD3 with its academic base in UT’s College of Pharmacy and
Pharmaceutical Sciences has heretofore been WAY AHEAD OF ITS TIME! The
lessons we have learned by hard-knocks may only be partially applicable in general
- it will be interesting to see how many of the new ones will survive over time.
And for Med Chem: Our day in the ‘sun’ may have finally arrived because what’s
needed most amid the mix of all new technologies is ‘hit follow-up’ based upon
directed libraries, molecular probes to establish SAR, and intelligent (knowledgedriven) drug wannabe development programs cognizant of ADMET issues that may
need to be addressed rather than trigger total abandonment of an efficaciously
promising lead.
60
THANK YOU !
61
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