Personalized neoantigen cancer vaccine assembled on DC targeting antibody improves cancer immunity

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Y. Mishima1*, F. Isoda1, N. Matsumoto1, N. Watanabe1, K. Hiranuka1, T. Yamada1, N. Fujinami2, M. Shimomura2, T. Suzuki3, T. Nakatsura2, and N. Nakamura1
1 BrightPath Biotherapeutics Co., Ltd., Kawasaki, Japan, 2 Exploratory Oncology Research & Clinical Trial Center,*Email contact:

National Cancer Center, Kashiwa, Japan, 3 Department of Pharmacology, School of Medicine, Teikyo University, Tokyo, JapanResults

We developed a novel vaccine platform (BP1209vaccine) in which we employed peptides consistingof a neoantigen-epitope and an IgG binding motif.
The peptides form a divalent peptide complex per
antibody molecule by simply mixing with therapeutic
antibodies in physiological condition. Initially, we
selected ovalbumin (OVA) as a model antigen andevaluated the efficacy of this vaccine format in
combination with DC-targeting antibodies in vivo.
Next, we generated series of neoantigen peptides inboth human and murine origins using in-housebioinformatic algorithms and evaluated theadvantages of this vaccine platform.

DC-targeting
antibody

Dendritic cells

vaccinepeptide

1500

polyICLC

OVA-BP1209 peptide + αCD40vaccine

OVA-BP1209 peptide(non-IgG-binding)
OVA-BP1209 peptide + αCD40(non-IgG binding)

500

005X

XFX

F

Fc-binding
motif (17aa)

CD4+ T cells

Fc-binding motif (17mer in red) non-covalently binds to Fc-region ofDC-targeting antibodies, resulting efficient antigen delivery to DC.

200OVA-BP1209 peptide

vaccine1000

01015Days after Inoculation

Fig. 1 BP1209 OVA-peptide or BP1209 OVA-peptide with mutations thatimpairs IgG binding capacity were administrated EG.7 tumor baring micewith or without anti-CD40 Ab on day 3 and day10. The mice treated withBP1209 vaccine with anti-CD 40Ab exhibited tumor regression in all themice tested, while the vaccine lacking IgG binding property + anti-CD40 Ab
did not induce complete tumor regression, suggesting that enhanced
antitumor efficacy results from the assembly of peptide-antibody complex.

BP1209 neoantigen vaccine exerted robust
antitumor effect in therapeutic setting
1400
12004006006ELISPOT spot number / 2x10 splenocyte

Fig. 3 We developed neoantigen prediction pipeline .
►Related Abstract was presented on Poster #1911/15
We predicted 30 neoantigen epitopes from the genomic sequence ofMC-38 tumor cells. The neoantigen peptides in length of 27aa (SLPs)
and 27aa with an IgG-binding motif (BP1209 vaccine) weresynthesized. SLPs or anti-CD40 Ab-conjugated BP1209 peptides
were administrated C57BL/6 three times at weekly intervals. CTL
induction were analyzed by ELISPOT using spleens from these mice.

BP1209 vaccine accumulates in DCs in lymphonode via DC-targeting antibody
cDC120cDC215
105Group

123FAM-peptide-++α-CD40 Ab--+

polyICLC+++

12312800

3Fig. 4 A fluorescent labeled BP1209 vaccine peptide was inoculated
subcutaneously with or without anti-CD40 antibody. Six hours later,
proximal lymph nodes were resected and the peptides uptake into
cDC1 and cDC2 were quantified by flowcytometry.

polyICLC
Adpgk BP1209 peptide
Adpgk BP1209 peptide +mCD40Ab600
vaccine

400Adpgk BP1209 peptide +Atezolizumab

vaccineAtezolizumab (IP)200071421

Days after Inoculation

28Fig. 2 Mice were subcutaneously inoculated with MC-38 cells on day 0.
Anti-CD40 Ab or Atezolizumab were subcutaneously administrated
with or without BP1209 neoantigen vaccine peptide for Adpgk on day
4 and 11. The mice treated with BP1209 vaccine exhibited delayedtumor growth. Notably, Atezolizumab conjugated BP1209 vaccine
maintained complete tumor regression in all the mice until study end(n=9).

8642Group12345OVA peptide(BP1209 format)--+-+

OVA peptide(non-IgG-binding)-+-+-

αCD40 mAb-++--

Atezolizumab---++polyICLC+++++

GzmB+/TCF1+

40GzmB-/TCF1+(Stem-like TEX)
GzmB+/TCF1-

20

4000
2000
00
polyICLC

polyICLC
polyICLC+BP1209-Pep. +BP1209-Pep.
+CD40 Ab.

GzmB-/TCF1-

polyICLC

polyICLC+BP1209-Pep.

polyICLC+BP1209-Pep.
+CD40 Ab.

Fig. 6 BP1209 vaccine peptide against Adpgk were subcutaneously
administrated to MC-38 tumor baring mice with or without anti-CD40 Ab.
After two vaccinations at weekly intervals, tumors were harvested andused for TIL analysis. Mice treated with the BP1209 vaccine had amarked increase in Adpgk-specific TIL (Left). The BP1209 vaccine
increased TCF1+ / Granzyme B- Stem-like exhaust T cells (TEX) (Right).

Conclusion● We developed neoantigen prediction pipelineand validated the accuracy by the analysis
using patient derived neoantigen and HLAtransgenic mice. (in detail, Poster #1911/15)● BP1209 neoantigen vaccine promote stemlike TEX infiltration into tumor.
● BP1209 vaccine provides an ideal option
to improve neoantigen vaccine therapy.

Disclosure

Mishima Y.: Employee of BrightPath Biotherapeutics

0Group20000

60● Binding ability of peptides to IgG is essential
for the enhanced antitumor efficacy.

BP1209 vaccine enhances in vivo CTL responseby combining with DC-targeting antibodies

1000

40000

80

● BP1209 vaccine dramatically enhanced CTL
induction compared to conventional vaccine
and exhibited robust anti-tumor effect in vivo.

0Group10060000

Freaqency (%)

BP1209vaccine0CD8+ T cells

Dextramer+ TIL/(g) tumor

2000

Tumor volume ± SEM (mm3)

Schematics of BP1209 vaccine

BP1209 neoantigen vaccine strongly enhances
Stem-like TEX infiltration into tumor

27mer SLPvaccine*The study was approved by IRBs and GDS at both
National Cancer Center Japan and BrightPath Biotherapeutics.

BP1209 vaccines allow CTL immune-inductionof weakly immunogenic neoantigen epitopes

FAM+ cells in DC (%)

Methods

Peptide-antibody binding is critical for enhanced
therapeutic potential of BP1209 vaccine

Tetramer+/CD8+T cell(%)

Personalized neoantigen cancer vaccines havedemonstrated robust tumor-specific immunityand preliminary evidence to cure patients withmelanoma and other cancers. To improve theefficacy of personalized cancer vaccine, weherein, describe a novel vaccine platform using
neoantigen peptides that contain a high affinity
binding motif for dendritic cell (DC)-targeting
antibodies.

Tumor volume ± SEM (mm3)BackgroundX

mishima_y@brightpathbio.com

123

45Fig. 5 BP1209 OVA vaccine exhibited an enhanced CTL induction whenadministrated with anti-CD40 Ab or atezolizumab. Vaccine peptides without
antibody-binding property had limited response even administered with
antibodies, suggesting that vaccine-antibody binding is critical forenhanced immune-induction.

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