1. Summary of Initial SAR Analysis
Initial SAR study focused on four areas of the molecule:
 Hydroxyl group: Replacement with H or F abolished antimalarial activity.
 tert-Butylamine: A variety of amines tolerated, but none better then tert-butyl.
 tert-Butyl group: Substituted phenyl tolerated, but increased lipophilicity.
Reduced activity observed for small lipophilic or polar groups.
 Chlorophenyl group: Heteroaromatic replacements improved activity.
SAR of Heteroaryl Analogs
Pyridine analogs chosen for further optimization studies.
Identification of 2-aminomethylphenol antimalarials with potent in vitro and in vivo activity against Plasmodium blood stages
Gavin D. Heffernan,1 David P. Jacobus,1 John W. Anderson,1 Peter Krasucki,1 Kurt W. Saionz,1 Guy Schiehser,1 Hong-Ming Shieh,1 Wenyi Zhao,1 Arba Ager,2
Marina Chavchich,3 Geoffrey Birrell,3 Dennis Shanks,3 Michael Edstein.3
1Jacobus Pharmaceutical, P.O. Box 5290, Princeton, NJ 08540, USA, 2University of Miami, Miller School of Medicine, Miami, FL 33136, USA
3Australian Army Malaria Institute, Weary Dunlop Drive, Gallipoli Barracks, Enoggera, QLD 4051, Australia.
.
Summary
 Replacing the chlorophenyl group of WR 194,965 with pyridines or pyrimidines
improved antimalarial activity.
 Optimization of the pyridine series afforded JPC-3210 which displayed potent in
vitro activity against chloroquine-sensitive and chloroquine-resistant parasites.
 Exceptional in vivo antimalarial activity observed for JPC-3210.
 JPC-3210 overcame the hERG liability present in the lead and exhibited a
favorable pharmacokinetic profile.
References
1. World Health Organization World Malaria Report 2014.
2. Peters, W. et al. Annals of Tropical Medicine and Parasitology 1984, 78, 567-579.
3. Desjardins, R. E. et al. Antimicrob. Agents Chemother. 1979, 16, 710–718.
4. Ager, A. L. Experimental models: rodent malaria models (in vivo). In Handbook of experimental pharmacology: antimalarial
drugs; Peters, W., Richards, W. H. G., Ed.; Springer Verlag, New York, NY, 1984; vol 68, pp 225-254.
5. ChanTest Corporation, Cleveland, OH 44128
Synthesis of Heteroaryl Analogs
Reagents and conditions: (a) Br2, CH2Cl2, 0oC to rt, 99% yield; (b) MEMCl, iPr2NEt, CH2Cl2, 0oC to rt,
99% yield; (c) nBuLi, B(OiPr)3, THF, -78 to -10oC, 99% yield; (d) HetArX, Pd(PPh3)4, K2CO3, H2O, DME,
80oC; (e) 1M aq. HCl, MeOH, 60oC; (f) (CH2O)n, tBuNH2, iPrOH, reflux; (g) 1M aq. HCl, EtOH, rt.
Introduction
 Worldwide, more than 3 billion people are at risk of being infected with malaria and
in 2013 an estimated 584,000 deaths were attributed to the disease.1
 New antimalarial drugs are urgently needed due to the development of resistance to
current treatments.
 WR 194,9652 was selected as the starting point of a medicinal chemistry program.
 Exhibited potent in vitro activity against two P. falciparum lines, the chloroquine-
sensitive D6 line, and the chloroquine-resistant W2 line.
 Substantial hERG inhibition a major drawback of WR 194,965.
JACOBUS
PHARMACEUTICAL
WR 194,965
Pyridine Analogs Focused SAR Study
 Trifluoromethylated analogs (1, 2 & 12) displayed excellent in vivo activity
 Corresponding 2-pyridyl (13) and 2-pyrimidyl (14) isomers notably less active
Methods:
In vitro Antimalarial Testing:
Parasite susceptibility to test compounds was determined by measuring the inhibition of
[3H]Hypoxanthine uptake in a whole blood isotopic assay (1% starting parasitemia).3
In vivo Antimalarial Testing (Modified Thompson Test):
Survival and parasite clearance in male CD1 mice infected with P. berghei (1% parasitemia)
were measured for 31 days. Test compounds were administered twice daily by oral gavage on
days 3–5. Mice that survived for 31 days and were blood-film negative were considered cured.4
hERG Testing:
Drug interactions with the hERG potassium channel, responsible for the cardiac 'rapid' delayed
rectifier current (IKr), were determined using a manual patch clamp assay.5
Activity of Optimized Compounds
Mouse PK Data for JPC-3210a
 High oral Cmax achieved (1,180 ng/mL, 2.96 mM), very long half-life (7 days).
 Excellent bioavailability (86%).
 Plasma levels of JPC-3210 exceed the P.f. D6 IC50 for >28 days after a single
16 mg/kg dose (data not shown).
aIn male CD1 mice. Results are the mean of n = 3
bIn 5% Tween in phosphate buffered saline. cIn.0.1% Tween80/0.5% hydroxyethylcellulose in water.
 In vitro activity improved 3-fold over the lead WR 194,965.
 JPC-3210 8-fold more active in vivo than WR 194,965.
 No hERG liability observed for JPC-3186 and JPC-3210.
Compound 2 Compound 12
WR 194,965 JPC-3186 JPC-3210
P.f. D6 IC50 (nM) 31 10 9
P.f. W2 IC50 (nM) 28 9 8
Curative dose
(Thompson test)
32 mg/kg/day 8 mg/kg/day 4 mg/kg/day
hERG IC50 (mM) 1.1 >10 >10
Route of
Administration
/ Dose
Tmax (h)
Cmax
(ng/mL)
t1/2 (h)
AUC0-last
(h*ng/mL)
Clearance
(mL/h/kg)
Vol. of
Distribution
(mL/kg)
F (%)
IV
b
/ 2 mg/kg 0.083 847 139 16,100 116 23,200 NA
Oralc
/ 16 mg/kg 2 1,180 169 111,000 119 29,000 86
Compd. HetAr
P.f. D6
IC50 (nM)
Thompson test
survival at day 31
@ Dose/day
Compd. HetAr
P.f. D6
IC50 (nM)
Thompson test
survival at day 31
@ Dose/day
1 13
7/7 @
8 mg/kg
8 25
7/7 @
64 mg/kg
2 10
7/7 @
8 mg/kg
9 350
0/7 @
32 mg/kg
3 25
4/7 @
8 mg/kg
10 23
0/7 @
64 mg/kg
4 19
3/7 @
16 mg/kg
11 24
1/7 @
64 mg/kg
5 67
0/7 @
64 mg/kg
12 9
7/7 @
4 mg/kg
6 64
4/7 @
64 mg/kg
13 231
0/7 @
64 mg/kg
7 23
5/7 @
64 mg/kg
14 6,300 Not tested