L mh node, imented macro-hates
`
`Bone marrow,l m-hoid _erminal center
`
`dd dose-dependent
`nd not determined
`
`Reversibility of findings at 100 mkd HD afier 2 wks (3‘mo study), or 4 wks (1-year study):
`
`Reversible were: body weight changes, RBC/Hb/Hct changes (partial in l-yr study), serum Ca, serum P (partial),
`ALT, AST, cholesterol, triglyceride, CK changes, urine changes in f (1-year study), thymus involution, liver
`necrosis
`
`Not reversible were: RBC/Hb/Hct changes in 3-mo study
`
`APPEARS THIS WAY
`0N ORIGINAL
`
`APPEARS nus WAY
`ONORIGINAL
`
`‘
`
`90
`
`

`

`
`AUG parem
`
`
`
`(ngxh/mL)
`
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`
`EXPOSURE MULTIPLES ARENT DRUG IN RAT AND MONKEY TOXICITY STUDIES
`
`
`
`.
`
`AUC
`metabolite M7
`‘ (ngxh/mL)
`
`AUC multiple
`RAT:HUMAN*
`(parent)
`M/F
`
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`metabolite M7
`(ngxh/mL)
`(ng/mL)
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`ngxh/ml.
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`studies
`MONKEY oral toxicit
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`Study Nr.
`Doses
`(mg/kg/d)
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`
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`
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`
`(mg/ks/day)
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`Cmax
`(ng/mL)
`
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`parent
`n 1 Xh/mL
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`AUC multiple
`DOG:HUMAN*
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`m/ f
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`da dosm lwk
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`
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`
`_
`
`APPEARS THIS WAY
`.ONORIGINAL
`
`APPEARS THIS WAY
`- 0N ORIGINAL
`
`92
`
`

`

`HUMAN PK data
`
`PK of parent drug was evaluated in human subjects with chronic renal failure in an ascending,
`multiple-dose, double-blind, randomized, placebo-controlled study (#20000187). Each subject
`received a dose for days (once daily), starting with 25 mg or placebo, and if no dose-limiting
`toxicity occurred afier >= 7 doses, the dose was increased by 25 mg. Maximum dose was 300
`mg. Doses were given sequentially; Blood samples were taken on study days 4, 6, 7 of each
`period, and at 0.5, 1, 2, 3, 4, 6, 8, 12, 24h after dosing. N=22 (4f, 18m). Total dosing time was
`up to 12 weeks. N=17 received AMG073, and N=5 received placebo. N=8 completed all dose
`levels.
`'
`
`Results: T max was 2-3h. Exposure (Cmax, AUC) was linear with. dose up to \— . This
`suggests doses >200 mg may not provide additional clinical benefit. Steady state
`concentrations (trough) were achieved by Day 4 of each period.
`
`Pharmacoklnetic Results:
`Large intervlndivldual variations were observed In subjects' pharmacoklnetic
`parameters, with some apparent outlying values. For this reason, median
`pharmacokinetlc values were examined and are presented in the following table:
`
`;
`(ng/mL)
`l
`EMedian
`
`’
`
`Auqe24)
`(ng-hr/mL)
`N Median
`Range
`
`Range
`
`'
`Values are presented as 3 significant figures.
`NOTE Pharmaooklnetlc parameters were not calculated for Subjects 14. 18. and 110 at the
`175-. 150-. and 250-mg doses. respectivety. because no day 7 profile was obtained.
`Parameters for Subfect 18 were also not calculated at the 125mg dose because sample tubes
`were broken. No parameters at doses > 175 mg were determined lor Subject 4 because
`AMG 073 concentrations were very low or undetectable, The 200mg dose parameters for
`Subbct 9 were not used In the determlnation o! summary statistics because the day 6 dose
`was missed.
`Source: Appendix 13
`
`APPEARS nus w .
`0N ORIGINAL Av
`
`93
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`

`

`MAIN TOXICITIES: SUMMARY
`Tabulation of main toxici
`findin and LOAELs in chronic > l-mo studies
`“m“
`
`LOAEL
`m_
`; da
`5
`2
`
`Clinical signs: abnormal breathing,
`deli diation, salivation
`Clinical signs: abnormal feces, poor appetite,
`emesxs
`'
`
`-
`
`—
`
`LOAEL
`m_
`1 da
`
`5-l00
`
`Phairnacologic drug effect (hypocalcemia)
`
`o
`-
`Pharmacolo chru effect
`
`
`
`
`
`H c
`
`_
`
`A c
`
`_
`
`Liver toxici
`Liver toxici
`Liver toxicit
`Renal toxici
`Muscle/cardiac toxici
`
`Liver toxici
`
`/e
`
`e induction
`
`——— C
`
`ardiotom
`Renal loxici
`
`
`
`
`
`
`
`MKI!Ut‘JILIil/iMGkl!LittletliLIILIILIill‘OOOOOOO90OO
`
`» _
`
`
`
`
`
`
`
`_R
`
`BC, Hb, Hct decrease
`
`— U
`
`rine Na K decrease
`Urine s ! '
`ific ; vi
`
`decrease
`
`— A
`
`lbumin and/or nrotein decrease
`Creatinine increase
`Creatine kinase increase
`
`Testosterone decrease
`VitD decrease, T3 decrease T4 increase
`
`He atic P450 content increase
`
`Kidne wei_ht increase
`Testis wei_ tdecrease
`
`Heart necrosis
`Kidne mineralization
`
`
`
`
`
`
`
`
`
`
`
`I-m—pocalcemia nartl
`.rc .rolonation
`_ _
`;
`Btu/minced
`FC reduced
`
`NNNUINMNMNMUIUiUiUiLIIUtLIIthltLIILIILIIM
`
`100
`IOO
`
`
`
`
`
`
`in + f averaec
`AUC multi les in 6-mo rat and l2-mo monke stud
`Dose
`AUC parent
`AUC multiple
`m_ _da
`n ; xh/mL
`
`
`
`
`
`E e toxici
`
`1- ocalcemia
`
`Testicular toxici
`
`I___
`1055 Ill-—
`_
`m—
`——
`_
`m3-
`_—
`IE.—
`—_
`13x
`II!—
`IE_
`- IE—
`
`
`
`
`
`
`
`
`
`kwxlWNWAu0
`
`94
`
`— _
`—I
`
`_
`-2
`_ 5
`IE-
`—
`—
`Monke
`-—
`
`_—
`
`55
`
`

`

`SUMMARY AND EVALUATION OF TOXICITY FINDINGS
`
`In animal toxicity studies, single or repeat doses of cinacalcet caused a reduction1n serum
`calcium, and this hypocalcemia1s a confounding factorin all toxicity studies. Not only did the
`hypocalcemia cause phannacologic/physiologic effects per se, but the presence of
`hypocalcemia may also have masked CaR-mediated effects of the test compound. It should be
`noted that patients with secondary HPT on dialysis are monitored for hypocalcemia and this _
`event can be controlled. The drug treatment is intended to reduce increased serum PTH levels
`but not to levels leading to hypocalcemia. Thus, the hypocalcemia-mediated events in the test ‘
`animals are not directly relevant. In addition, potential CaR-mediated effects in the treatment
`population that might resemble effects of increases in serum calcium may have gone
`undetected in the preclinical studies.
`
`Exposure multiples for parent drug attained in chronic rat and monkey studies were moderate '
`(rat) to low (monkey). Dose administration in animals was limited by the calcium-lowering
`effect of the drug (rat), or G1 toxicity (emesis, monkey): Also, in the monkey, exposure to
`parent drug did not clearly increase above the high dose of 100 mg/kg/day. The latter may
`have been due to limited dissolution and absorption, first pass metabolism, and perhaps auto-
`induction. Exposure multiples for the major human metabolite (M5) were lower than for
`'
`parent in both rat and monkey. However, multiples for the closely related compound, M7,
`were very large. Multiples for MZ-Glu were adequate in the monkey. The M5, M7 and M2-
`Glu metabolites are considered inactive at the CaR.
`
`Sponsor attributed several animal toxicity findings to hypocalcemia: clinical signs (salivation,
`twitching, convulsions) in rats, mice and dogs, GI finding of hyperplasia/inflammation in the
`rat, decreased hematologic measures (RBC, Hb, Hot) in the monkey, and cataract formation in
`the rat. Toxicity findings of emesis (dog, monkey), increased liver weight and decreased
`testosterone (monkey) were ascribedto an action of cinacalcet independent of hypocalcemia.
`Other findings in toxicity studies were not specifically discussed.
`
`' Clinical signs and hypocalcemia
`In the single dose studies in rodents, there was reduced activity, abnormal gait and posture,
`- quivering, respiratory signs, tremors. In the'14—da‘y and 28—day rat toxicity studies, numerous
`clinical signs were observed, especially at the 500 mg/kg/day high dose, and most of them
`appeared to be signs of CNS- or GI toxicity. Breathing problems, dehydration and salivation
`persisted at relatively low doses in the 6-month rat study. Hypoactivity and tremors were also
`seen in single and multiple dose studies in dogs. GI toxicity was seen mainly in dogs and
`monkeys.
`
`'
`
`HypocalCemia leads to nerve excitability (membrane destabilization) and neuromuscular
`irritability. Thus, respiratory effects, tremors, motor disturbances, convulsions, and GI
`motility effects in rodents and dogs were probably related to low calcium levels. Excessive
`salivation in rats, dogs and monkeys may also have been related to hypocalcemia.
`
`In a single dose mouse study, a dose of 200 mg/kg (ca. 6x human dose of 180 mg/day, based
`on mg/mZ) had no proconvulsant effect (defined as potentiation of the effect of electroshock
`
`95
`
`

`

`on the tonic extension of hind limbs). In acute toxicity studies in rats and mice, at oral doses ’
`up to 500 mg/kg in mice (6x human mg/mZ dose), and 1500 mg/kg in rat (80x human mg/m2
`dose), no convulsions were observed. Serum calcium was transiently decreased, based on data
`from single dose pharmacology studies in rats. In a 14-day repeat dose rat study (50, 250, 500
`mg/kg/day), on Day 6, convulsions were seen in 3/10 animals at the 500 mg/kg/dose (23x
`human AUC of 648 mgxh/mL @ 180 mg/day). In this study, serum calcium was decreased at
`all doses from Day 1. In the 6—month rat study with 5, 25, 100 mg/kg/day (up to 7.5 x human
`AUC), no convulsions were observed. Thus, convulsions were seen in rats at high doses at
`which there was also serum Ca reduction and may be due to hypocalcemia. The convulsions
`may also have been the result of an interaction with central neurotransmitter receptors or ion
`channels (e.g. adrenergic, dopaminergic, GABA-B).
`
`
`
`In an acute oral rat toxicity study with 100, 250, 500mg/kg, .
`
`clinical signs of hyper- or hypoactivity, tremors,
`'convulsions, excessive salivation were observed at all doses 2100 mg/kg (equivalent to $200
`mg/kg parent compound, based on molecular weight comparison). It is unclear whether these
`effects were due to interaction of this degradant/metabolite with the parathytroid CaR and
`hypocalcemia-induced CNS effects since serum calcium was not measured, or whether they
`represent metabolite-specific (CaR-independent) CNS toxicity. The NOAEL for these effects
`
`and the multiple of human exposure to the
`metabolite are also unclear.
`
`p
`GI effects
`GI toxicity included soft feces and/or GI distension in acute and 14-day mouse and rat studies
`at high doses, 80?: feces and poor appetite in monkey (at 20.1x human AUC), and vomiting in
`monkey and dog. In a safety pharmacology study in mice, a dose of 200 mg/kg (6x human
`mg/m2 dose) increased GI motility. Stomach erosion was seen in rat at 7.5x human AUC. The
`emesis in dog and monkey occurred at a 0.03x-2x multiple of human exposure (human AUC
`= 648 ngxh/mL, @180 mg/day) in dog and monkey. Tolerance to emesis developed-in the 1—
`month dog study. The emesis was drug-related and, as suggested by Sponsor, it may have .
`been due to transient hypocalcemia or a CNS effect of cinacalcet. However, a direct role of
`the CaR in the GI events can not be excluded. The CaR is present along the GI tract and has
`' been implicated in the modulation of gastrointestinal secretion and motility, mineral ion
`homeostasis, and epithelial cell growth and differentiation (Brown et al, 1998).
`
`In the 6-month rat study, an increased incidence of cecurn mucosa] hyperplasia/inflammation
`was observed at al doses including the lowest dose of 5 mg/kg/day (0.1 x human AUC). It was
`. not seen in the 2-year dietary carcinogenicity studies at doses between 5-50 mg/kg/day (0.2-
`2.5x human AUC). This effect may have been due to interaction with the CaR in the intestine
`at Cmax/Tmax, or it may have been related to fluctuating drug levels. Gastrointestinal
`epithelial cells can respond to extracellular Ca and CaR activation with
`differentiation/proliferation (Brown et al, 1998). The intestinal effect was not seen in dog or
`monkey and its clinical significancein unclear.
`
`Body weight
`Body weight effects in rats (mainly) and monkeys were at least partly related to reduced food
`consumption. The effects were small in the monkey, and were likely the result of GI toxicity.
`
`‘96
`
`

`

`Effects were more pronounced in the rat at doses where higher exposures were attained, e.g.
`body weight gain was minimally affected at 1.5x human AUC (25 mg/kg) in the 6-month rat
`study, but was decreased by 40% at 7x human AUC (100 mg/kg).
`
`'
`
`’
`Hematology _
`In monkeys (3- to 12-month studies) rats (14-day study) and dogs (l-month study), red blood
`cell parameters (RBC, Hb, Hct) were slightly ,to' moderately decreased at doses ~1.-2x human
`exposure @180 mg/day, an effect that was transient or slowly reversible upon dose
`discontinuation. The cause of this effect is unclear. Sponsor attributed it to reduced food
`consumption and body Weight gain, Or an action on the CaR which has been found in murine
`bone-marrow derived stem cells. Clinical monitoring has not revealed an effect on Hb or Hot
`(Study # 20000188). Reduced WBC was also observed in monkeys and rats at higher doses
`(2-10x human exposure).
`
`~
`’
`Coagulation
`Prothrombin time (PT) and APTT were slightly increased in repeat dose rat and monkey
`studies at the mid or high doses equivalent to 21,5x human exposure. The effect was no longer
`observed after 6 months in monkeys. The effect was slight (10%) but statistically significant.
`The cause of this finding is unclear, but it may be related to inhibition of calcium-dependent
`clotting factors or impaired hepatic clotting factor production. There was some indication of
`'liver pathology (increased weight in rat and monkey, and necrosis and vacuolation in
`monkey).
`
`Ophthalmoscopy
`Cataract formation was observed in rats in all repeat dose studies at 22x human exposure
`@180 mg/day. As suggested by Sponsor, cataracts may have been caused by hypocalcemia,
`and evidence for such an effect of ocular hypocalcemia in animals and humans is present in
`the published literature (Delamere et a1, 1981). Cataracts have been observed in individuals
`' with hypoparathyroidism. Hypocalcemia can cause derangement of lens electrolyte
`composition. Cataracts were not seen in dog or monkey studies, even though hypocalcemia
`occurred to a similar degree in monkeys dosed with 100 mg/kg/day(40% reduction). Cataract
`formation may have been mediated by the CaR which is present in lens epithelial cells (Brown
`and Macleod, 2001).
`
`'.
`‘
`'
`'
`‘
`Electrocardiography
`. In a 171110ch study in beagle dogs (0, 5, 50, 100 mg/kg/day) there were no effects on EKG
`parameters, including QT and QTc intervals. QTc intervals were between 0.23 and 0.25 sec @
`pre—treatment and @4 wks, in all groups. Serum ionized calcium was decreased maximally
`8%, 19%, 20% in LD, MD, HD.
`Cmax (Day 28) ranged from Q ——‘— . (up to 1.7x human Cmax), and AUC from 21 to
`500 ngxh/mL (up to 0.8x human AUC) in LD-HD.
`
`Effect on serum ionized Ca H 7.4 normalized and serum arent dru_ l-month do- stud ,
`
`
`Cmax (ng/mL)
`‘
`Tmax=l-2h
`
`
`
`
`
`[_
`—
`
`
`
`Ca predose
`m_/dL mmol/L
`5.8 1.45mM
`5.9 1.48mM
`
`Ca post dose (4h)
`m /dL mmoI/L
`5.8 1.45 mM
`5.6 1.40mM
`
`
`
`-
`"'7
`
`
`
`
`
`97
`
`

`

`
`
`Cmax human (180 mg/d):
`
`,In a 3-month toxicity study in monkeys, QTc was increased dose-dependently at all doses of
`5, 50, 100 mg/kg (0.1-2x human AUC @ 180. mg/day): The maximum increase in QTc was
`from 0.26 sec in controls to 0.32 sec in HD group. Serum ionized calcium was reduced from
`1.35 mmol/L in controls, to 0.9 mmol/L ( i.e. -35%) in the 100 mg/kg HD group. Sponsor
`stated that the QTc effects in monkeys were attributed to hypocalcemia, and a linear
`correlation between serum Ca and QTc was established (rr = -0.7). However, Sponsor also
`stated that the QTc prolongation was not biologically significant in the monkeys.
`
`I Tc data from 3-month monke stud (avera _e, m+
`
`
`Dose (mg/kg)
`Serum romzed Ca (Wk QTc
`(Wk 13) (sec)
`'
`12) (0 24h avg)
`mmol/L
`
`'
`
`Cmax
`(ng/mL)
`
`AUC
`(ngxh/mL)
`
`
`
`
`
`_—_ _— _
`
`I_-/
`
`
`
`
`_—.
`
`
`
`
`
`v
`
`
`
`
`In a 12-month monkey toxicity study, there were also QT and QTc prolong'ations, most
`pronounced at 3 and 6 months, but less at 10 and 12 months, at 5, 50, 100 mg/kg/day (0.15-2x
`human AUC @ 180 mg/day). QRS interval appeared unchanged. QT prolongation was due to
`' a lengthening of the ST segment. The maximal QT(c) effect was 60 'msec (0.26sec in controls
`to 0.32 sec @100 mg/kg/day)'when serum ionized calcium was reduced from 1.35 to 0.8 mM.
`It is unclear why the QT effect in monkeys is attenuated after 6 months despite continuing
`hypocalcemia. Sponsor ascribed the QT effect in the monkey to hypocalc'emia, and the ‘
`diminution of the effect upon long term (>6 month) treatment to loss of responsiveness of the
`heart to low calcium.
`‘
`
`0 Tc data from 12-month monke stud males
`
`
`Wk 52 ,
`Cmax
`AUC
`
`(ng/mL)
`(ngxh/mL)
`Wk26+52
`
`
`
`
`
`Dose
`(mg/kg)
`
`Wk 26
`
`Serum Ca
`(0-24h avg)
`mmol/L
`
`QTc
`(sec)
`
`Serum Ca
`(0—24h avg)
`- mmol/L)
`
`. QTc
`(sec)
`
`—_
`
`.
`
`
`
`The cause of the discrepancy between dog and monkey QT data is unclear.
`
`98
`
`

`

`An association of the QT increase with hypocalcemia is likely. The relationship between
`calcium and QT(c) in monkeys was similar as has been described for patients with
`‘ hypoparathyroidism and hypocalcemia (Bronsky et al, 1961), and for volunteers given citrate
`to lower serum calcium (Davis et al, 1995). In these cases, a decrease in serum ionized
`calcium of 0.5 mmol/L was associated. with an increase in QT(c) of 60 msec, and a decrease
`of 0.2 mM with an increase in Qta(c) of 34 msec, respectively. This compares to an increase
`of 60 msec in the monkey. However, it can not be excluded that the QT increase due to
`cinacalcet may partially be due to an other drug-related event. In an in vitro safety
`pharmacology study, KATP channel and two voltage dependent K channels (Kv4.3, Kv1.5) .
`which may play a role in cardiac conduction were inhibited by 96%, 45%, 20%, respectively, ‘
`by 500 ng/mL. Blockage of these channels might lead to calcium-independent effects on
`cardiac conduction. HERG channels were minimally inhibited by 12% at 500 ng/mL
`(1.27uM) prompting moderate clinical concern. Other in vitro studies have not been
`conducted.
`
`Serum chemistry findings (calcium, phosphorus) .
`The main finding was a dose-dependent reduction in serum calcium in all animal species at all
`dose levels tested in toxicity studies (down to 0.03x human exposure). Increases in serum P
`were observed at the same doses or a level higher. The Ca and P changes were at least partly
`related to the intended pharmacologic effect of the drug, i.e., suppression of parathyroid PTH
`release. PTH stimulates renal reabsorption of calcium across the distal convoluted tubule and
`inhibits reabsorption of phosphate in the proximal tubule, hence reduction in PTH lowers
`serum Ca and increase serum P. Decreases in serum PTH were observed at the same dose
`
`levels as the decrease in calcium, but a clear dose-dependence was not established in either
`rat, dog or monkey. In the rat effects on calcium may also have been mediated by increase in
`serum calcitonin and suppression of bone resorption. The effects on Ca and P may also have
`been mediated by other CaR than those in the parathyroid gland eg. in the kidney It has been
`suggested that calcium can inhibit its own reabsorptionin the distal tubule (Blankenship et al,
`2001), and a calcimimetic may exert this same action.
`
`In the repeat dose rat studies the changes in calcium and phosphate lead to increases in CaxP
`product, while in the monkey this was not observed. The increased CaxP product was also .
`observed in rat and mouse 24—month carcinogenicity studies, where vascular or cellular
`mineralization occurred in several soft tissues. Kidney mineralization (pelvis diverticulum)
`was seen in the 6-month rat study at 25— 100 mg/kg/day doses (>1.5x human AUC), possibly
`resulting from increased serum CaxP product, or from distal tubule precipitate formation due
`to increases in urine calcium concentrations.
`
`‘
`
`Liver
`
`A number of observations suggest a potential fer liver effects and/or toxicity. There were
`slight increases in serum ALT and AST at the high dose (100 mg/kg/day) in 3-month and 12—
`month monkey studies (2x human AUC, respectively). ALT was also increased in repeat—dose
`rat studies at doses as low as 50 mg/kg/day (2.2x human AUC). Serum protein and/or albumin
`were decreased in l—month and 6-month rat studies rats (100 mg/kg/day, 7.5x human AUC)
`and albumin was decreased in the 150/ 100 mg/kg group in the 3-month monkey study (2x
`human AUC). Liver weight increase was seen in >l-month studies in rats and monkeys at 25
`
`99
`
`

`

`and 50 mg/kg/day (1.5-2x human AUC). Liver necrosis and liver cell changes that were
`possibly drug-related occurred in the 12-month high dose monkeys (2x human AUC).
`
`In the 1-year monkey study, hepatic cytochrome P450 content was increased in the high dose
`group (100_ mg/kyday) after 6 and 12 months (1.8-1.4x control value). Also, CL/F (l/h/kg)
`. was increased at 6 and 12 months as compared to Day 1, in the 100 mg/kg group as compared
`to control. Sponsor concluded that this suggests modest induction of hepaticP450 enzymes.
`.
`However, in the 3-month monkey study no dose-related increases in CL/F was observed after
`1 or 3 months as compared to Day 1. In the rat, in the 6-month study, no evidence of
`significant induction based on parent drug clearance or liver weight was observed.
`
`The P450 increase, liver weight changes and increased clearance in the monkey suggest a
`potential for induction or auto-induction of cinacalcet-metabolizingenzymes. In humans,
`there was no indication of induction or auto-induction of hepatic P450 enzymes based on the
`linear dose response of plasma exposure (Cmax, AUC) up to doses of 180 mg/day. However,
`the observed saturation of exposure to parent drug at higher doses may be partially explained,
`by auto—induction of metabolism at higher dose levels. Induction and/or auto-induction could
`affect the clearance of drugs metabolized by the various CYP450 enzyme isoforms including
`those involved in the metabolism of cinacalcet (3A4, 1A2, 2C9).
`
`Kidney
`Renal effects were observedin the rat, dog and monkey. In the rat, serum BUN was increased
`(1.4x human AUC) and creatinine was increased (7. 5x human AUC) accompanied by kidney
`mineralization (1.4x human AUC). In the monkey, kidney weight was increased in the
`monkey (2x human AUC), and there were slight tubualr changes. The cause of the weight
`increase was unclear. Urine volume was increased in dogs and monkeys and urinary calcium
`excretion was increased in rats and dogs. The volume and ion excretion effects were probably
`due to pharmacologic effects on the kidney CaR, which18 thought to play a rolein calcium
`reabsorption and urine concentrating ability.
`Renal toxicity is particularly relevant for patients with primary hyperparathyroidism.
`
`Other findings
`In rats, in 2-week, l-month and 6-month toxicity studies, histopathologic findings of
`myocardial necrosis/degeneration were observed at doses of 1.4x human AUC and higher.
`The cause of this effect is unclear. It may be secondary to myocardial effects of hypocalcemia,
`or to a block of protective KATP potassium currents resulting in Ca overload and myocardial
`damage. Creatine-kinase increase and muscle degeneration occurred at 100 mg/kg (2x human
`AUC) in 3- to 12-month monkey toxicity studies. The data suggest a potential for myocardial,
`cardiovascular or muscle toxicity.
`
`'
`
`Endocrine changes were observed in the 12-month monkey study. Serum testosterone levels
`were markedly decreased at all doses of 5-100 mg/kg/day (0.1-2x human AUC @ 180 -
`mg/day) in the 1-year monkey study. This was accompanied by testicular weight decrease at
`100 mg/kg/day. Testicular tubular atrophy or degeneration was also observed in the l-and 6-
`month rat studies at 50—100 mg/kg/day (3-7.5x human AUC @ 180 mg/day), and the l-month
`dog study at 100 mg/kg/day (0.8x human AUC @ 180 mg/day). In monkeys, Vitamin D was
`
`100
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`

`

`decreased and thyroid T3 was decreased and T4 increased at 50'mg/kg/day (1.5x human
`AUC). The cause of these endocrine organ effects18 unclear. Sponsor reported no testicular
`changesin clinicla trials (Study20000188).
`
`In the 6-month rat toxicity study, there were effects on bone size (reduced length, increased
`diameter), but BMD of trabecular or cortical bone was not clearly affected. The increase in
`bone diameter may have been due to periosteal expansion possibly as a,result of fluctuating
`PTH levels.
`
`In juvenile 3-week old rats, cortical bone area was increased at the expense of trabecular bone,
`possibly due to decreased cortical bone resorption in the fast growing skeleton.
`In juvenile 10-week old dogs, afier 1 month of recovery from 1 month of treatment, there was
`slightly increased incidence of left ventricular arterial hypertrophy, and myocardial fibrosis, at
`a dose leading to 1/10 of human exposure. The etiology of this finding is unclear, but might be '
`related to irreversible KATP channel blockage.
`
`Findings of unclear origin were thymus weight and histology changes, bone marrow changes,
`low incidences of histological changes in monkeys of unclear significance.
`
`PK and AUC multiples
`PK studies showed qualitatively similar metabolite profiles in all species, with parent drug
`comprising a minor part (<1%) of total drug related material. However, there were large
`quantitative differences in metabOlite levels between species, and the multiples for the main
`metabolite observed in humans (M5) were abouthalf those for parent in rats and monkeys. A
`larger multiple (13x) for the minor metabolite (MZ—Glu) in humans was achieved in the
`chronic monkey studies. Metabolite multiples for the dog are unknown.
`The calculated multiples of human AUC are based on median human exposure and are subject
`, to large variation.
`
`The M5 and M7 metabolites were >300-fold less active on the CaR in an in vitro system. The
`M2 metabolite did not interact with the CaR. However, both parent and metabolites may
`contribute to other (toxic) effects unrelated to CaR activation. The toxicity of M6 (circulating
`in humans) is likely to be similar to that of M5 and M7. The differences in toxicities between
`rats and monkeys may have been partly due to species differences in exposure to parent and
`metabolites and species difference'sin biological response to these compounds.
`
`In all species, upon dealkylation of the parent, naphthalene-group containing metabolites are
`formed at unknown levels Upon acute oral and subchronic inhalation, naphthalene (active
`ingredientin moth balls) can cause toxicity in humans including neurotoxicity (convulsions),
`GI effects, hepatic effects, renal effects and ocular effects including cataracts. In rats, at oral
`doses of 400 mg/kg for 3 months, clinical signs, kidney and thymus lesions, and anemia have
`been observed. Interestingly, there'appears to be some similarity between these effects and the
`
`preclinical toxicities observed with cinacalcet. The acute rat toxicity study with
`suggested potential CNS toxicity of this metabolite/cleavage product with unknown effect on
`serum calcium.
`
`lOl
`
`

`

`,
`.
`_
`CONCLUSIONS
`Rat, dog and monkey studies with, cinacalcet were carried out by the oral route using daily
`dose administration. In studies of 23 month duration in rats and monkeys, exposure to parent
`drug was up to 7.5 and 1.8 times, respectively, the exposure attained in humans treated for
`secondary hyperparathyroidism with the maximal dose of 180 mg/day. Exposures in humans
`at the highest dose proposed for primary hyperparathyroidism (360 mg/day) was in a similar
`range as the exposure at 180 mg/day. Thus, multiples for this dose/indication‘are similar as
`those for the secondary HPT indication.
`
`Preclinical studies were suboptimal due to the dose-limiting effects of hypocalcemia and GI
`toxicity (MTD). GI toxicity was either hypocalcemia—related or the result of drug-related G1 or
`CNS toxicity. The main target organs of cinacalcet identified in studies with drug-induced
`hypocalcemia are CNS, heart (EKG), GI tract, eye, liver, kidney, intestine, endocrine/
`reproductive organs, bone marrow, thymus, spleen, lymph nodes.
`
`Apart from hypocalcemia, the data from animal toxicity studies suggest the following
`potential clinical safety concerns: GI toxicity, hematologic effects (anemia), hepatic toxicity,
`renal toxicity, liver enzyme induction, myocardial and skeletal muscle toxicity, endocrine
`effects (testosterone, thyroid hormones, Vitamin D). Moreover, it can not be excluded that the
`EKG abnormalities, CNS toxicity (seizures), and cataracts observed in animals may have a
`calcium-independent component.
`
`Other toxicities not predicted by animal data due to CaR activation and resembling
`hypercalcemia may also occur in humans. A theoretical concern is the potential effects on
`mGluR and GABABR in brain or pancreas, which might lead to interference with central
`nervous system electrical activity or insulin secretion.
`
`Because metabolism is an essential feature in cinacalcet PK, the potential for toxicity is
`enhanced in cases where systemic exposureto parent and/or metabolite is increased, e. g. in
`hepatic or renal impairment.
`'
`.
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`0N ORIGINAL
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`3.4.3. Genetic toxicology
`
`An Ames assay was performedwith Salmonella Typhimurium (TA98, TAlOO, TA1535, TA .
`1537), at concentrations up to 250 ug/plate in the absence of S-9,_and at concentrations up to
`750 ugplate in the presence of 8-9. Concentrations up to 750 ug/plate were tested in E. Coli
`(WPZ uvrA), with and without S-9. concentrations were selected based on results of toxicity
`assays performed at doses up to 5,000 ug/plate. Cinacalcet tested negative in all strains with
`and without metabolic activation.
`
`A HGPRT forward gene mutation test was performed using CHO cells. Cinacalcet was not
`mutagenic in this assay with and without metabolic activation.
`
`A chromosomal aberration assay was carried out in CHO cells, with and with out 8-9. Cells
`were harvested at 4 and 20 hours. Cinacalcet was negative for induction or structural and
`numerical chromosome aberrations.
`
`A mouse micronucleus study was conducted at doses up to 200 mg/kg orally. Cinacalcet did
`not induce micronucleus formation in this assay.
`
`.
`Summary
`Cinacalcet tested negative in vitro in the Ames test in S.typhin_1urium and E.Coli, the HGPRT
`mammalian cell gene mutation assay, and the CHO cell chromosome aberration assay, with
`and without metabolic activation, and in viva in'the mouse micronucleus assay.
`
`APPEARS THIS WAY
`0N ORIGINAL.
`
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`3.4.4. Carcinogenicity
`
`NOTE: For brief summary ofcarcinogenicity studies, see Executive CAC meeting
`minutes (APPENDIX)
`
`Adequacy of the carcinogenicig studies and appropriateness of the test model:
`Carcinogenicity studies in rats and mice were performed using the dietary route, because of
`the difficulty dosing animals for 2 years via gavage due to behavioral changes (agitation,
`sensitivity) resulting from the pharmacologic effect of hypocalcemia. Dietary dosing provides
`for fewer fluctuations in serum drug and calcium concentrations. Doses were adequate and
`were selected based on 3—month dietary studies (EXEC CAC Meeting Minutes September 22,
`1998). The high dose in the female rat study was adjusted after 1 year of study due to
`excessive body weight effects, in consultation with the EXEC CAC (Meeting Minutes January
`4 l l, 2000). The presence of Cinacalcet in initial plasma samples from control animals in rat and
`mouse studies was most likely the result of post sample collection contamination. This issue
`was reviewed by the Division and it was concluded that the integrity of the studies was
`maintained (EDP-2 Meeting Minutes November 9, 2001). Both studies were adequate and
`acceptable.
`
`3.4.4.1. Mouse Carcinogenicity Study
`
`Study title. 104 Week Carcinogenicity Study of AMG 099073-011n Mice with
`Administration by Diet.
`
`Key study findings:
`0 CD- 1 mice were dosed with 0,15,50, 100 mg/kg/day (males), orO, 30, 70, 20,0 mg/kg/day
`(females)1n the diet for 104 weeks.
`
`0 Doses resulted in parent AUC levels of 109,366, 941 (m) ngxh/mL and 198, 401, 1050 (f)
`ngxh/mL, equivalent to 0.2x, 0.6x, 1.5x (males) and 0.3x, 0.6x, 1.6x (females) the human
`AUC (648 ngxh/mL) at a daily dose of 180 mg/day.
`’
`0 There were no significant effects of Cinacalcet on survival. Convulsions and agitation
`related to hypOcalcemia were seen in MD (m) and HD(m,f). An increased incidence of
`cataracts and lens opacities was seen in MD (m) and HD (m,t).
`o Cinacalcet induced a dose-dependent reduction in body weight gain (gr) in MD and HD
`(m,f). Food consumption (gr/day) was minimally decreased in MDm and HD m, f.
`Efficiency of food utilization was decreased111 all treated The HD was the maximum
`tolerated dose (MTD) based on the body weight effects.‘
`I 0 There was a sustained, dose--dependent decre