LNG-451 (BLU-451), a potent inhibitor of EGFR exon 20 ...

LNG-451 (BLU-451), a potent inhibitor of EGFR exon 20 insertion mutations with high CNS exposure

Paul G. Pearson,1 Anjali Pandey,1 Bruce Roth,1 Tracy Saxton,1 Daniel J. Estes,1 Ravi Trivedi,2 Himanshu Agrawal,2 Gurulingappa Hallur,2 Ishtiyaque Ahmad,2 Helen Jenkins,1 Brion W. Murray1

1Lengo Therapeutics, Cambridge, MA, USAa; 2Jubilant Biosys Limited, Bengaluru, Karnataka, India. aA wholly owned subsidiary of Blueprint Medicines Corporation, Cambridge, MA, USA.

Poster Number 3261

50 mg/kg QD 10 mg/kg QD

2 mg/kg QD 50 mg/kg QD 25 mg/kg QD 10 mg/kg QD

5 mg/kg QD 25 mg/kg BID

5 mg/kg BID 1 mg/kg BID 50 mg/kg QD 10 mg/kg QD Mobocertinib 30 mg/kg QD Mobocertinib 30 mg/kg QD 50 mg/kg QD 10 mg/kg QD 50 mg/kg QD 10 mg/kg QD

phosApchtiov-iptEhyGooFsfApRcht(iov%-i)tEyGoFfR (%)

IC50, nM BLU-451B(LngU/-4m5L1) (ng/mL)

Background

? Epithelial growth factor receptor (EGFR) exon 20 insertions (ex20ins) are oncogenic driver mutations that constitutively upregulate EGFR kinase activity, are the third most common type of activating EGFR mutation, and are not potently targeted by many inhibitors of common activation mutations such as L858R and exon 19 mutations1

? EGFR ex20ins are in-frame insertions of 1 to 7 amino acids in the C helix or following the C helix2 with the three most prevalent insertions V769_D770insASV, D770_N771insSVD, and H773_V774insNPH accounting for half of the cases1

? Since brain metastases are common in non-small cell lung cancer (NSCLC) with 30% of patients developing them during the course of their disease, brain penetrant EGFR-directed therapies are necessary for better treatment outcomes3

? While there are approved therapies such as mobocertinib and amivantamab and others in clinical development, none have demonstrated meaningful central nervous system (CNS) activity, and can be associated with treatment-limiting adverse events, including wild-type (WT) EGFR-mediated toxicities4,5

? BLU-451 (formerly known as LNG-451) was designed as a covalent inhibitor to potently inhibit EGFR ex20ins mutations, spare WT EGFR, and be CNS penetrant

Methods

? BLU-451 activity was tested in tumor cell lines and Ba/F3 engineered cell lines expressing EGFR mutations as well as cell lines dependent on WT EGFR

? BLU-451 in vitro and in vivo characterization was performed in a range of pharmacokinetic (PK) studies to assess brain penetration and to measure efflux ratios in cell lines over-expressing MDR1 and BCRP

? The in vivo antitumor and CNS activities of BLU-451 were assessed in a PC9-luc intracranial tumor model

Results

Figure 1: BLU-451 inhibited EGFR ex20ins in cell proliferation models (A) and led to regression in xenograft tumor models (B)

A. Potency in cell cytotoxicity assays

1000

100

10

1

BLU-451

Mobocertinib

WT EGFR

SVD

SVD-Ph

ASV

NPH

B. Dose dependent tumor growth inhibition, % relative to vehicle

Ba/F3 xenograft model harboring EGFR ex20ins (V769_D770insASV)

FQEA

Osimertinib

NPG-Ph

Ex20ins PDX (LU-0387, LXFE 2478)

191%

190%

122% 96% 88%

100%

86% 73% 62%

106%

79% 64%

105% 76%

119% 108%

66%

'

59%

BLU-451

BID, twice daily; IC50, half-maximal inhibitory concentration; PDX, patient-derived xenograft; QD, once daily.

BLU-451

Figure 2: BLU-451 is not a substrate for P-glycoprotein (MDR1) or breast cancer resistance protein (BCRP) and therefore not subject to prominent efflux mechanisms in cells

Efflux ratios (B-A / A-B) ? in vitro assays

Caco-2

4.5

4.1

4

3.5

3

2.5

2 1.5

1.5

1

0.7

0.5

0 BLU-451OsimertiniMb obocertinib

MDCK-MDR1

25

20

19.1

15

10

5

1.1 1.2

0 BLU-451OsimertiniMb obocertinib

MDCK-BCRP

1.2

1.1

1

0.8

0.6 0.6

0.4 0.4

0.2

0 BLU-451OsimertiniMb obocertinib

? Figures 3A-B shows BLU-451 PK in Balb/C mice models at 2 mg/kg, 10 mg/kg (AUC ~4,590 ng-h/mL), and 50 mg/kg

? BLU-451 treatment resulted in suppression of EGFR phospho-Tyr1068 (activation marker) in a Ba/F3 EGFR ex20ins V769_D770insASV tumor model (Figure 3C)

? Extended BLU-451 pharmacodynamic half-life is expected as EGFR turnover was reported to be 27 hours6

Figure 3: BLU-451 was orally bioavailable in mice and its covalent mechanism of action resulted in prolonged suppression of EGFR ex20ins activation in tumors

A. BLU-451 PK (oral) in mouse

10000

A. BLU-451 PK (oral) in mouse

10000 1000

1000 100

50 mg/kg 10 mg/kg 2 mg/kg 50 mg/kg 10 mg/kg 2 mg/kg

IC50 ASV 77 nM

100 10

IC50 SVD 51 nM IC50 ASV 77 nM

10

1

0

6

12

1

B. BLU-451 P0K parameters in mo6use

Dose

Tmax

Cmax

(mg/kg)

(h)

(ng/mL)

Time (h)

12

TCim24eh (h) (ng/mL)

2

1.0

25

BLQ

C. In15h00ibition of pho10s..05pho-EGFR ac16,,t16iv69i34ty by BLU-4B55L.18Q

IC50 SVD 51 nM 18

18

AUC(0?24) (ng?h/mL)

71.6 4,289 24,340

AUC(0-) (ng?h/mL)

117 4,590 24,360

24

24

T1/2 (h) 2.68 3.06 2.34

C. Inhibit1io00n of phospho-EGFR activity by BLU-451

80

100 60

80 40

60 20

40 0

20 0

4

8

12

Time (h)

0

0

4

8

12

Time (h)

BLU-451 50 mg/kg BLU-451 10 mg/kg

BLU-451 50 mg/kg BLU-451 10 mg/kg

16

20

24

16

20

24

AUC(0?24), area under the curve for 0?24 hours; AUC(0?), area under the curve extrapolated to infinity; BLQ, below limit of quantitation; C24h, concentration at 24 hours; Cmax, maximum concentration; T1/2, half-life; Tmax, time to maximum concentration.

? Brain-to-plasma ratios were determined in mice and rats following oral doses of BLU-451. Absolute values (Figure 4A) are shown for brain (ng/g) and plasma (ng/mL)

? Rat brain-to-plasma ratios were determined after BLU-451 30 mg/kg oral dose (AUC0 ? 8h) (Figure 4B)

? BLU-451 was evaluated in rat CNS steady state intravenous infusion models to derive the following PK parameters

? High steady-state brain and plasma levels (874 ng/g, 431 ng/mL)

? Brain to plasma ratio = 0.62

? Cerebrospinal fluid (CSF) levels: 26 ng/mL (suggesting 2.96% free in brain given the lack of transporter activity7),

? Unbound brain (CSF) /unbound plasma concentration ratio = 0.66 (2.77% free in rat plasma) in a rat CNS steady state intravenous infusion model

Figure 4: BLU-451 demonstrated CNS exposure

A. Brain and plasma ratios (and concentrations) of BLU-451

Study

Mouse (Balb/C ? male) PO, @ 1 h Mouse xenograft PO, 10 days, 1 h Rat PO @ 1 h

PO, oral.

BLU-451 50 mg/kg

0.72 2450/3399

0.59 4326/7375

1.10 2835/2571

B. Brain and plasma AUC(0-8h) of BLU-451 30 mg/kg oral dose

Brain (ng-h/g) Plasma (ng-h/mL)

10,041 9,771

BLU-451

0

5000

10000

ng-h/g (brain)/ng-h/mL (plasma)

15000

? Anesthetized animals were incised along the skin over the midline to expose coronal and sagittal suture junctions and luciferase-expressing PC-9-luc tumor cells (2 ? 105) were injected into the right lateral ventricle

? PC9 cells carry EGFR exon 19 deletion mutations

? Half-maximal inhibitory concentration (IC50) for BLU-451 in PC9-luc in vitro cell growth inhibition model was 13 nM

? BLU-451 treatment resulted in tumor regression in a PC9-luc human lung cancer intracranial murine tumor model (Figure 5A)

? Whole animal luciferase bioluminescence imaging (BLI) demonstrated that BLU-451 treatment resulted in brain tumor regression and suppression of metastatic dissemination (Figure 5B)

? Ex vivo analysis showed that BLU-451 reduced luminescence in the brain and spinal cords consistent with activity in the CNS compartment (Figure 5C)

Figure 5: BLU-451 is a CNS penetrant, mutant EGFR inhibitor with activity demonstrated in a PC9-luc human lung cancer intracranial murine tumor model

A. BLU-451 resulted in tumor regression in PC9-luc human lung cancer intracranial murine tumor model

100000 10000 1000

Vehicle control BLU-451 2.5 mg/kg BLU-451 25 mg/kg

BLI (photons/s?105)

100

10

1

8

11

14

17

20

23

26

29

Days post tumor implantation

Figure 5: (continued)

BB..WWhhooleleaannimimaallluluccififeerraasseebbioiolulumminineesscceenncceeimimaagginingg

VVeehhicicleleccoonntrtorol l

BBLLUU-4-4551122.5.5mmgg/k/kgg

BBLLUU-4-455112255mmgg/k/kgg

141#4# 181#8# 212#1# 272#7# 333#3# 363#6# 434#3# 454#5# 505#0# 606#0# DD99

7#7# 151#5# 161#6# 242#4# 313#1# 353#5# 373#7# 414#1# 575#7# 595#9#

1#1#

101#0# 171#7# 262#6# 303#0# 444#4# 494#9# 535#3# 565#6# 585#8#

Luminescence

Lum5i.n0escence 5.0

3.0 x107

3.0 1.0

x107

Radianc1e.0 (p/Rseacd/icamnc3e/sr) Co(lpo/rseScc/aclme 3/sr) MMiaCMnxoin==lor=55S.. 500c.a000leee075e5

Max = 5. 00e7

DD1212

DD1616

DD1919

D23 D23

DD2626

DD2828

CC..EExxvvivivoobbrraaininaannddssppininaallccoorrddlulumminineesscceenncceeaannaalylyssisis

14# 14#

18# 18#

21# 21#

27# 27#

33# 33#

43# 43#

45# 45#

50# 50#

60# 60#

Vehicle Vehicle

7#7# 2.5 mg/kg B2L.5Um-4g5/1kg

BLU-451 1#1#

2B52BL5UmLUm-g4-/g54k/1g5k1g

151#5#

161#6#

242#4#

313#1#

353#5#

373#7#

414#1#

575#7#

595#9#

101#0#

171#7#

262#6#

303#0#

444#4#

494#9#

535#3#

565#6#

585#8#

Conclusions

? BLU-451 is a WT EGFR sparing, selective, CNS-penetrant investigational EGFR ex20ins covalent inhibitor ? BLU-451 was not a substrate for P-gp (MDR1) or BCRP in in vitro assays which is consistent with the potential for CNS activity ? BLU-451 was orally bioavailable in mouse and rat ? BLU-451 showed an extended pharmacodynamic half-life for inhibition of EGFR phosphorylation in tumors, as expected given its covalent mechanism of action

? In a murine intracranial tumor model, BLU-451 treatment resulted in measurable tumor regression

? These in vitro and in vivo PK and pharmacodynamic results strongly support a first-in-human phase 1/2 clinical trial of BLU-451 in patients with advanced or metastatic solid tumors harboring EGFR ex20ins mutations (NCT05241873)8

References

1. Riess JW et al. J Thorac Oncol. 2018;13:1560?8; 2. Vyse S et al. Signal Transduct Target Ther. 2019;4:5; 3. Remon J et al. Front Oncol. 2018;8:88; 4. Riely GJ et al. Cancer Discov. 2021;11:1688?1699; 5. Park K et al. J J Clin Oncol. 2021;39:3391?340; 6. Yates JWT et al. Mol Cancer Ther. 2016;15; 2378?2387; 7. Lin JH. Curr Drug Metab. 2008;9:46-59; 8. Study of BLU-451 in Advanced Cancers With EGFR Exon 20 Insertion Mutations. NCT05241873. . Accessed March 14, 2022.

Acknowledgements

Editorial support was provided by Deborah R. Cantu, PhD and Travis Taylor, BA, all of Paragon, Knutsford, UK, supported by Blueprint Medicines Corporation, Cambridge, MA, according to Good Publication Practice guidelines.

Disclosures

PGP, AP, BR, TS, DJE, HJ, and BWM were employees of Lengo Therapeutics, formerly of San Diego, California, when this study was conducted. RT, HA, GH, and IA are employees of Jubilant Biosys Limited, Bengaluru, India. Data in this poster were generated by Lengo Therapeutics and its collaborators.

Poster available for download at:

Presented at AACR Annual Meeting 2022, April 8?13, 2022. Please contact medinfo@ for permission to reprint and/or distribute

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