Rodman & Renshaw Annual Global Investment Conference September 2011

1. Rodman & Renshaw Annual Global Investment Conference September 2011

2. Forward-Looking Statements This presentation contains forward-looking statements that involve substantial risks and uncertainties. These statements are often, but not always, made through the use of words or phrases such as "anticipates," "expects," "plans," "believes," "intends," and similar words or phrases. All statements, other than statements of historical facts, included in this presentation regarding our strategy, future operations, outlook, milestones, the success of Arno’s product development, potential advantages of Arno’s product candidates, future financial position, future financial results, plans and objectives of management are forward-looking statements. We may not actually achieve these plans, intentions or expectations and Arno cautions investors not to place undue reliance on our forward-looking statements. Actual results or events could differ materially from the plans, intentions and expectations disclosed in the forward-looking statements we make. Various important factors that could cause actual results or events to differ materially from the forward-looking statements that we make. Such factors include, among others, risks that the results of clinical trials will not support our claims or beliefs concerning the effectiveness of our product candidates, our ability to finance the development of our product candidates, regulatory risks, and our reliance on third party researchers and other collaborators. Arno is providing this information as of the date of this presentation and does not undertake any obligation to update any forward-looking statements as a result of new information, future events or otherwise.

3. What Differentiates Arno Therapeutics Three oncology drug candidates with unique MOAs Highly differentiated products for unmet medical needs with substantial market potential Leadership team with records of success in oncology drug development and commercial outcomes Strong patent position on all assets 2

4. Global Product Success Glenn R. Mattes, President & CEO 25+ years of R&D, commercialization and managerial experience ; Taxotere®, Lovenox®, Remicade®, Prezista®, Doxil®, Procrit®/Eprex® J. Chris Houchins, Chief Operating Officer 20+ years of global drug development experience; Celebrex®, Aromasin®, Ellence®, Emcyt®, Temodar®, Intron®/Peg-Intron®, Caelyx® Stefan Proniuk, PhD, MBA, Senior Director Product Development 15+ years of global CMC drug development experience, multiple NCEs and approved products; Triaminic®, Niravam ® Alex Zukiwski, MD, Chief Medical Officer 16+ years of global pharmaceutical industry experience; Taxotere®, Xeloda®, Procrit®/Eprex®, Velcade®, Doxil®, Yondelis®, FluMist®/Fluenz® Arie Belldegrun, MD, Executive Chairman of the Board Professor and Chair of Urologic Oncology, UCLA Founder of Agensys and Cougar Biotechnology (Zytiga™)

5. Potential Labeling Drives Development HIGHLIGHTS OF PRESCRIBING INFORMATION These highlights do not include all the information needed to use AR-42 safely and effectively. See full prescribing information for AR-42. AR-42 tablets for oral administration ----------------------------RECENT MAJOR CHANGES-------------------------- Indications and Usage, XXXXXXXXXX XXXXXXX XXXXX XXXXX (1) Warnings and Precautions, Rash (5.2) Warnings and Precautions, Fatigue (5.2) --------------------------INDICATIONS AND USAGE---------------------------- AR-42 is a pan-histone deacetylase (HDAC) inhibitor indicated for the treatment of patients with: XXXXXXXXX XXXXXXXXX XXXXXX XXXXXXX XXXXXXXXXXXXXX who require therapeutic intervention but are not candidates for curative surgical resection(1). XXXXXXX who require therapeutic intervention but are not candidates for curative surgical intervention or radiation therapy(1). AR-42 in combination with XXXXXXXX is indicated for the treatment of patients with XXXXXXXXXX XXXXXXX XXXXX XXXXX after progression of at least one prior platinum containing chemotherapy regimen (1).

6. Product Candidates

7. AR-42 Profile Pan-DAC inhibitor; oral formulation In vitro and in vivo activity demonstrated in multiple tumor types Greater potency and efficacy vs. vorinostat in AML models Encouraging results in multiple cancers and leukemic stem cells Phase I/II study in hematological malignancies and solid tumors is currently ongoing

8. AR-42 Profile Phase II program anticipated to begin in 2Q2012 Potential Indications Non-small cell lung cancer Prostate cancer Cranial-spinal axis tumors Carcinoma of the urothelium Hepatocellular carcinoma Acute myelogenous leukemia

9. AR-42 Phase I/II Study Dose escalation phase to define MTD in study subjects with hematological malignancies N~20 patients A solid tumor dose escalation arm is being added Tumors of “interest”; N = ~21 MTD expansion phase N~30 patients, 10 subjects in each cohort (chronic lymphocytic leukemia, multiple myeloma and Hodgkin’s disease) Trial Design Standard 3+3 study dose escalation study, oral administration 3x/week on non-consecutive for 3 consecutive weeks of a 28 day treatment cycle Assessment in both phases for biomarkers of target inhibition, including histone and tubulin acetylation, as well as other potential markers for treatment changes or toxicity Study endpoints: Safety , PK, PD, preliminary efficacy 8 8 8

10. Minimal Regrowth of Ben-Men-1-LucB Xenografts After AR-42 Treatment 1 6 + AR-42 (months) 0 2 3 + Normal diet (months) 1

11. AR-12 Profile Potential first-in-class; targeted PDK-1 inhibitor; oral formulation Phase I/II study in solid tumors and lymphomas currently enrolling Potential Indications NSCLC Breast cancer

12. AR-12 MOA TargetsPI3K/Akt Pathway AR-12

13. AR-12 Combination Potential Preclinical data show increased activity and/or reversal of resistance when combined with: Tarceva® (non-small cell lung cancer, in vitro and in vivo) Iressa® (non-small cell lung cancer, in vitro and in vivo) Avastin ® (colon cancer, in vivo) Herceptin ® (breast cancer, in vitro) Tamoxifen (ER positive and negative breast cancer, in vitro and in vivo) Gleevec ® (chronic myelogenous leukemia, in vitro) Nexavar ® (nasopharyngeal cancer, in vitro) Tseng PH et al., Mol Pharmacol. 2006 Nov;70(5):1534-41 Cen L et al., British J Cancer (2007) 97, 785-791 Ping-Hui Tseng et al, Blood (2005) 105: 4021-4027

14. AR-12 Phase I/II Study • Dose-escalation to determine MTD and/or active biologic dose in subjects with solid tumors and lymphomas • Study is ongoing • Early evidence of biologic activity • Phase II expansion will allow for efficacy/safety assessments in tumors of interest

15. AR-67 Profile Third-generation camptothecin analogue Phase II glioblastoma multiforme study currently enrolling Phase II colorectal carcinoma study scheduled to start 4Q2011 Potential Indications Glioblastoma multiforme Colorectal cancer Non-small cell lung cancer Small cell lung cancer

16. AR-67 Summary Tert-butyl-silyl camptothecin derivative with substantially improved lactone stability, and increased lipophilicity ~ 85% remains in active “lactone” form potential increased central nervous system penetration potential for more predictable metabolism/toxicity Phase I study demonstrated anti-tumor activity; acceptable safety (no drug related diarrhea); linear pharmacokinetics Phase II GBM study proceeding after reaching interim assessment

17. Response Three Years after Initiation(Two Years after Last AR-67 Infusion) Pre-treatment / Baseline 3/3/08 Three years later 2/28/11 AR-67 Phase I, Subject 21

18. Market Potential CompoundIndicationUS Incidence AR-42 NSCLC 220,000 prostate 240,000 AML 12,900 bladder cancer 69,000 multiple myeloma 20,500 cranial/spinal tumors 13,000 AR-12 breast cancer 232,000 NSCLC 220,000 AR-67 GBM 10,000 colorectal cancer 140,000

19. Upcoming Milestones Expand AR-42 Phase I/II study into solid tumors of interest Complete AR-12 Phase I enrollment; identify indications for Phase II testing Complete AR-67 Phase II GBM study enrollment Initiate AR-67 Phase II colorectal cancer study

20. Reasons to Invest in Arno • Promising & differentiated oncology pipeline • Efficient, well-defined clinical/regulatory pathway with planned near term inflection points and potential expedited global registration programs • Senior management has record of success in oncology • New roadmap to value creation