G-200 Partnering Opportunity March 2012 Contact: Jonae R. Barnes jonae G-200 Partnering Opportunity March 2012 Contact: Jonae R. Barnes jonae.barnes@agenusbio.com www.agenusbio.com The patient is waiting.™ 1 1

Progress Update: Prophage Series G-200 NCI (CTEP) issued expedited approval for large, randomized Phase 2 trial of G-200 in recurrent GBM Decision by CTEP validates scientific basis and promising early results of G-200 in Phase 1/2 trial in recurrent GBM Planned Phase 2 study design is robust and could be sufficient for registration if results are positive Report on current, single-arm Phase 2 trial with G-200 to be presented at plenary session of AANS on 17 April 2012 Agenus seeks co-development partner to contribute $15MM to support Phase 2 trial in return for WW license rights

“Alliance Trial” G-200+Bevacizumab Multi-center, three arm, randomized trial PATH CONF I RMED GBM MANUFA CTURE ≥ 6 v I a l s G-200 + bevacizumab R A N D O M I Z E 18 Months Follow up S U R V I V A L G-200 alone followed by bevacizumab at progression RECURRENT GBM >90% RESECTION; KPS>70 Bevacizumab alone 1º Endpoint: Overall survival 2º Endpoints: Safety, Progression Free Survival Sample Size: HR: 1.5 (estimates 13.5 months median survival in combination arms vs. 9 months in bevacizumab)  (1-sided) = 0.05; Power = 80% Randomized 1:1:1; N = 255 (85 per arm) Dosing: G-200 given id 1x per wk for 4 wks; every other wk thereafter up to 12 total injections (up to 5 months of treatment). Bevacizumab given as standard dose (10 mg/kg) every 2 wks Potential Exploratory/Correlative Studies: -Immune response -B7H1 expression -PI3 Kinase activation -Molecular profiling (initial tumor tissue and on biopsy at presumed progression)

Rationale for Combination with Bevacizumab Bevacizumab currently represents best available therapy Potential for synergy: Bevacizumab as background therapy provides time for vaccine to work, theoretically pushing back emergence of resistance Synergy of VEGF-targeting agents + vaccines in preclinical models Increase in rate of tumor regression, improved survival, improved immune function1-5 Early human experience supports Avastin + active immune therapy Phase 1, Avastin + Ipilimumab in melanoma6 Phase 1, Avastin + Provenge7 Provocative mechanism of action Avastin reduces VEGF which is potent suppressor of APCs8 Avastin transiently normalizes blood vessels, allowing increased trafficking of T cells to tumor9 1. Li et al Clin Cancer Res 2006;12(22):6808-16. 2. Manning et al. Clin Cancer Res 2007;13(13):3951-9. 3. Imagawa et al. Auris Nasus Larynx 2004;31(3):239-45. 4. Gabrilovich et al. Clin Cancer Res 1999;5(10):2963-70. 5. Shrimali et al. Cancer Res ;70(15):6171-80. 6. Hodi et al. J Clin Oncol 29: 2011 (suppl; abstr 8511) 7. Rini et al. Cancer 2006;107(1):67-74.3. 8. Osada et al. Cancer Immunol Immunother 2008;57(8):1115-24. 9. Jain et al. Science 2005;307(5706):58-62.

Prophage Series Treatment Flow Standard of care surgery is performed to remove tumor tissue Tumor is shipped frozen to Agenus in Lexington, MA, USA Prophage series vaccine product is produced during the period while the patient recovers from surgery (~3 to 4 weeks) Product is shipped frozen to the hospital pharmacy or clinician Prophage series vaccine is given as a simple intradermal injection Agenus Manufacturing Facility

Market Opportunity Est. >$300M in revenue for GBM indications in US Multi-billion revenue opportunity for Prophage Series platform Most clinically advanced vaccine in recurrent GBM; limited competition on horizon Small, targeted sales effort Significant margins realizable even at moderate pricing Priced at $50K per patient gross margins are ~80%+ Positive commercial differentiators from Provenge® in considering an autologous product

Partnering Opportunity Agenus is looking for a co-development partner to advance Prophage Series G-200 in recurrent GBM Clinical trial costs mostly defrayed by Alliance-CTEP Additional funding required to ensure G-200 supply for duration of clinical trial at a cost of $15MM Terms for discussion: In consideration of funding, Agenus will provide world-wide licensing rights to G-200 with typical milestones and royalties