Vaccinex : Learnings from SIGNAL Phase 2 Study

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Learnings from SIGNAL Phase 2 Study	1

Forward Looking Statement

To the extent that statements contained in this presentation are not descriptions of historical facts
regarding Vaccinex, Inc. ("Vaccinex," "we," "us," or "our"), they are forward-looking statements
reflecting management's current beliefs and expectations. Such statements include, but are not
limited to, statements about our plans, expectations and objectives with respect to the results and
timing of our Phase 2 SIGNAL trial of pepinemab (VX15/2503) in Huntington's disease and other
clinical trials, the use and potential benefits of pepinemab in Huntington's disease and other
indications, and other statements identified by words such as "may," "will," "appears," "expect,"
"anticipate," "estimate," "intend," "hypothesis," "potential," "advance," and similar expressions or
their negatives (as well as other words and expressions referencing future events, conditions, or
circumstances). Forward-looking statements involve substantial risks and uncertainties that could
cause the outcome of our research and pre-clinical development programs, clinical development
programs, future results, performance, or achievements to differ significantly from those expressed or
implied by the forward-looking statements. Such risks and uncertainties include, among others,
uncertainties inherent in the execution, cost and completion of preclinical and clinical trials,
uncertainties related to regulatory approval, risks related to our dependence on our lead product
candidate pepinemab, the impact of the COVID-19 pandemic, and other matters that could affect our
development plans or the commercial potential of our product candidates. Except as required by law,
we assume no obligation to update these forward-looking statements. For a further discussion of
these and other factors that could cause future results to differ materially from any forward-looking
statement, see the section titled "Risk Factors" in our periodic reports filed with the Securities and
Exchange Commission ("SEC") and the other risks and uncertainties described in our Form 10-K dated	2
March 9, 2020 and subsequent filings with the SEC.

SEMA4D is progressively upregulated in NeuN+ neurons of HD mice

	Q175 transgenic mouse model of HD	HD-9.3M	WT-3M	WT-6M	WT-9.3M
	HD-3M	HD-6M
Sema4D
NeuN
Merge

• SEMA4D expression is upregulated in HD mice as disease progresses, compared to low expression in WT control.

• 1. SEMA4D is upregulated early in disease, prior to onset of symptoms, which occurs ~ 5 months of age in Q175 HD transgenic mice.
• SEMA4D co-localizes with NeuN+ neurons.

NeuN/Sema staining of retrosplenial cortex region of Q175 knock-in mouse model of HD and age-matched wild type (WT) littermate controls. Representative images are shown from analysis of 3 mice/time-point. M = months of age.

September, 2020 I 3

SEMA4D triggers collapse of actin cytoskeleton in astrocytes

A		B
Normal Control		rSEMA4D

Mean phalloidin area/cell

F-actin

Untreated rSEMA4D

PlexinB1 DAPI		PHALLOIDIN DAPI		PHALLOIDIN DAPI

September, 2020 I 4