Gritstone Oncology : COVID-19 Technical Program Presentation

Gritstone COVID-19 Vaccine Technical Information

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Safe Harbor and Forward-Looking Statements

This presentation contains forward-looking statements including, but not limited to, statements related to our preclinical and clinical product candidates, GRANITE, SLATE, CORAL and bispecific antibody programs. All statements other than statements of historical facts contained in this presentation, including statements regarding the timing of immunogenicity and clinical data for GRANITE SLATE, and CORAL, identification of development candidate for our bispecific antibody program, collaborations surrounding our infectious disease program, future results of operations and financial position, business strategy, prospective products, availability of funding, clinical trial results, product approvals and regulatory pathways, timing and likelihood of success, plans and objectives of management for future operations, future results of current and anticipated products, and our ability to create value are forward- looking statements. Because forward-looking statements are inherently subject to risks, uncertainties and other important factors that may cause our actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied by the forward-looking statements. The events and circumstances reflected in our forward- looking statements may not be achieved or occur and actual results could differ materially from those projected in the forward- looking statements.

Except as required by applicable law, we do not plan to publicly update or revise any forward-looking statements contained herein, whether as a result of any new information, future events, changed circumstances or otherwise. For a further description of the risks and uncertainties that could cause actual results to differ from those expressed in these forward-looking statements, as well as risks relating to the business of the company in general, see Gritstone's periodic filings with the Securities and Exchange Commission (the "SEC"), including its Quarterly Report filed on November 5, 2020 and any current and periodic reports filed thereafter.

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Summary

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First-generationCOVID-19 vaccines elicit strong, consistent antibody and CD4+ T cell responses against a single SARS-CoV-2 antigen (Spike). CD8+ T cell responses are more variable and limited.

Although compelling short-term protection has been demonstrated, durability of protection is currently unknown and may be impacted by emergent mutations in Spike

More complete and durable clinical protection will likely come from broader immune responses (including strong CD8+ responses) against a broader set of viral antigens, informed by studies of convalescent subjects

Gritstone has established strong relevant capabilities in key dimensions:

• T cell epitope identification & prediction - license agreement for validated SARS-CoV-2 epitopes with La Jolla Institute of Immunology and Gritstone's proprietary EDGETM HLA peptide prediction platform
• Vaccine vectors that elicit potent humoral and cellular immunity (including challenging CD8+ responses) in humans

• • In-houseGMP Biomanufacturing Facility (producing multiple clinical products for >2 years)
  • Clinical experience with the vectors, demonstrating relevant safety and immunogenicity
• Gritstone has designed and manufactured novel Spike and Spike + T cell epitope vaccines using both adenoviral and self-amplifying RNA vectors - Gritstone's CORAL program for COVID-19
• • Bill and Melinda Gates Foundation has supported the optimization of Gritstone's antigenic cassette

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A Phase 1 program led by NIH/NIAID/DMID has been designed to assess these new concepts in humans in 1H21

A Phase 2/3 program is expected to be run in 2H21 to address unmet need in subjects with sub-optimal (narrow, low titer or transient) responses to 1st generation vaccines

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Background