Investor Presentation October 2019 Forward-Looking Statements This - PowerPoint PPT Presentation

Science-Based Innovation-Focused ADC Company Investor Presentation October 2019

Forward-Looking Statements This presentation, in addition to historical information, contains certain forward- looking statements made pursuant to the Private Securities Litigation Reform Act of 1995. Such statements may involve significant risks and uncertainties, and actual results could differ materially from those expressed or implied herein. Factors that could cause such differences include, but are not limited to, new product development (including clinical trials outcome and regulatory requirements /actions); competitive risks to marketed products; forecasts of future operating results; availability of required financing and other sources of funds on acceptable terms, if at all; as well as those discussed in the Company's filings with the Securities and Exchange Commission. 2

T H E I M M U N O M E D I C S S T O R Y Company Transformed in Less Than Three Years Unique ADC platform May 2017 Validated target Multiple Phase 3 studies Large opportunities Global partnerships • Commercial • Clinical • Manufacturing Unencumbered asset Long IP protection From: A science focused company To: A fully integrated biopharmaceutical company 3

A Powerful Differentiated ADC Platform: Three Key Advantages 1. Payload – Validated & Well 2. Novel Linker Tolerated • Hydrolyzable linker for payload • ADC platform uses SN-38 as release payload of choice • Allows for intra- and extra-cellular • SN-38 kills cancer cells by (bystander effect) killing of tumor damaging DNA cells 3. Antibody – Highly Tumor Specific • hRS7 in sacituzumab govitecan targets Trop-2 in multiple solid tumor indications • Other pipeline assets: labetuzumab govitecan targets CEACAM5, IMMU-140 targets HLA-DR 4

Multiple Sacituzumab Govitecan Programs to Address Unmet Needs in Trop-2-Expressing Cancers Indication Designation Phase 1 Phase 2 Phase 3 Approval Partner mTNBC (3L+) BLA Submission mTNBC (3L) ASCENT Enrollment Completed HR+/HER2‒ mBC TROPiCS-02 mTNBC (1L) (+ Tecentriq) MORPHEUS New Study mTNBC / mUC / Ovarian (+ Rubraca) SEASTAR mTNBC / mUC / mNSCLC (+ Imfinzi) HER2 ‒ BC (Post-neoadjuvant) SASCIA New Study Urothelial (3L) TROPHY-U-01 Urothelial (3L) (Pending FDA Discussion) mNSCLC / H&N / Endometrial (Trop-2-enriched) TROPiCS-03 5

S A C I T U Z U M A B G O V I T E C A N F O R m T N B C – O V E R V I E W Highly Differentiated Therapy for mTNBC Treatment Line • mTNBC patients with at least 2 prior treatments in the metastatic setting The Unmet Need • Low response rates, short response duration and significant side effects with currently available therapies • Patients with pre-existing peripheral neuropathy or cardiac impairment may only have supportive care options Market Size • U.S. ~8k patients • EU5, Japan ~14k patients Status • Re-submit BLA in Q4 2019 6

Low Response Rates in Pre-treated mTNBC* Drug Phase N Population ORR (%) PFS (mos) 1st line treatment 1 st line Carboplatin 1 3 188 31 3.1 1 st line Docetaxol 1 3 188 36 4.5 1 st line (80.2%) Cis/Carboplatin 2 2 86 25.6 2.9 >1st line treatment Ixabepilone 3 2 60 Resistant to A, C & T or T only 6 - 17 1.6 - 2.7 Capecitabine 3 3 208 Prior or resistant to A & T 15 1.7 Eribulin 4 3 199 > 1 prior chemo 11 2.8 ESMO 2019 3 rd line mBC (~30% TNBC) Eisai 5 2 443 ~2.5 - 3.1 (erib, cap, gem) 2 nd line (60%), 3 rd line (40%) KEYNOTE-119 6 3 622 9.6 (K), 10.6 (chemo) 2.1 (K), 3.3 (chemo) * Includes breast cancer drugs with data from Phase 2/3’s with minimum mTNBC sample size > 60; ORR and PFS data Source of data: 1) Tutt A, SABCS 2014; 2) Isakoff SJ, J Clin Oncol 2015; 3) Perez EA, Breast Can Res Treat 2010; 4) Pivot X, Ann Oncol 2016 5) Kazmi S, ESMO 2019 Abstract 366P, 6) Cortes J, KEYNOTE-119, ESMO 2019 7

E V I D E N C E O F E F F E C T I V E N E S S Sacituzumab Govitecan Achieved Impressive ORR and PFS Compared to SoC in Late-Line mTNBC * ORR PFS (%) (months) 33 5.5 (N=108) (N=108) 18 2.8 2.7 15 11 1.7 Capecitabine Eribulin in Capecitabine Sacituzumab Eribulin in Taxane, Cap, Taxane, Cap, Sacituzumab in 2 nd line 2 2 nd line 1 in 2 nd line 2 2 nd line 1 Gem or Vin in Govitecan in Gem or Vin in Govitecan in 2 nd line 3 ≥3 rd line 4 2 nd line 3 ≥3 rd line 4 * Information is based on comparative results from independent studies 8 Source of data: 1) Pivot X, Ann Oncol 2016; 2) Perez EA, Breast Can Res Treat 2010; 3) Brufsky A, Breast Can Res Treat. 2012; 4) Bardia A, NEJM 2019

E V I D E N C E O F E F F E C T I V E N E S S Duration of Treatment Underscores Sacituzumab Govitecan Clinical Activity Median Last Prior Therapy 2.5 months Sacituzumab Govitecan 5.1 months Source of data: Bardia A, et al. Sacituzumab Govitecan-hziy in Refractory Metastatic Triple-Negative Breast Cancer. N Engl J Med. 2019; 380:741-51 9

Confirmatory ASCENT Study of Sacituzumab Govitecan Completed Target Enrollment Indication Twin Arm Study Endpoint mTNBC Sacituzumab govitecan Continue treatment 10 mg/kg IV ≥2 prior treatments until progression day 1 & 8, every 21 days OR N = 488  1 therapy for advanced Primary Endpoint disease who also • PFS Traditional chemotherapy progressed within 12 treatment of Secondary Endpoint months of (neo)adjuvant physicians’ choice* • OS therapy * Eribulin, gemcitabine, capecitabine & vinorelbine ASCENT Phase 3 Readout: H2 2020 National Institutes of Health. https://clinicaltrials.gov/ct2/show/NCT02574455 10

Metastatic Urothelial Cancer – Targeting our 2 nd High Unmet S A C I T U Z U M A B G O V I T E C A N F O R U R O T H E L I A L C A N C E R - O V E R V I E W Need Indication The Unmet Need • Current therapies for metastatic disease post chemotherapy and immune checkpoint inhibitors offer low response rate, short response duration and high toxicity Market Size • 3 rd line mUC – U.S. ~8k patients • 3 rd line mUC – EU5, Japan ~10k patients Status • May obtain accelerated approval based on results of Ph 2 TROPHY-U-01 trial 11

E V I D E N C E O F E F F E C T I V E N E S S Sacituzumab Govitecan Achieved Strong ORR and PFS Compared to SoC in Phase 1/2 Single-Arm Basket Study ORR PFS (%) (months) 7.3 31 (N=45) (N=45) 3.0 2.8 14 2.8 8.9 8.6 Vinflunine Docetaxel Docetaxel Vinflunine Docetaxel Docetaxel Sacituzumab Sacituzumab in 2 nd line 1 in 2 nd line in 2 nd line in 2 nd line 1 in 2 nd line in 2 nd line Govitecan in Govitecan in ≥ 3 rd line 4 ≥ 3 rd line 4 Phase 2 2 Phase 3 3 Phase 2 2 Phase 3 3 * Information is based on comparative results from independent studies 12 Source of data: 1) Bellmunt J, JCO 2009; 2) Petrylak D, JCO 2016; 3) Petrylak D, Lancet 2017; 4) Tagawa S, ASCO-GU 2019

Pivotal TROPHY-U-01 Study of Sacituzumab Govitecan Designed to Support Accelerated Approval Indication Single-Arm Study Endpoint mUC Continue treatment Cohort 1: Post platinum- until progression and CPI-based therapies Sacituzumab govitecan (N= 100) 10 mg/kg IV Primary Endpoint OR day 1 & 8, every 21 days • ORR (BICR) Cohort 2: 2 nd line post CPI Secondary Endpoint for cisplatin-ineligible • DoR, PFS & OS patients (N = 40) • First patient dosed in August 2018 in U.S. • Interim results presented at ESMO 2019 • Cohort 1 enrollment expected to be completed before YE 2019 13 National Institutes of Health. https://clinicaltrials.gov/ct2/show/NCT03547973

E V I D E N C E O F E F F E C T I V E N E S S Interim Results Confirm Clinical Activity in mUC Response Outcomes ORR in Patient Subgroups Category Subgroup ORR, % (n/N) Endpoint Cohort 1 (N=35) Overall N/A 29 (10/35) Median follow-up, mon 4.1 <75 29 (8/28) Age Patients continuing treatment, n (%) 20 (57) ≥75 29 (2/7) 0 33 (5/15) ORR, n (%) [95% CI] 10 (29) [15, 46] ECOG PS 1 25 (5/20) CR, n (%) 2 (6) 2 18 (2/11) No. prior anticancer PR, n (%) 6 (17) regimens ≥3 33 (8/24) uPR pending confirmation, a n (%) 2 (6) Yes 23 (5/22) Visceral involvement Liver 25 (2/8) at study entry Median time to onset of response, 1.5 (1.2, 2.8) mon (range) No 39 (5/13) 0-1 35 (10/29) a Follow-up scan is pending. CI, confidence interval; CR, complete response; ECOG PS, Eastern Cooperative Oncology Group Bellmunt risk factors Performance Status; ORR, objective response rate; PR, partial response; uPR, unconfirmed partial 2-3 0 (0/6) response. 14

E V I D E N C E O F E F F E C T I V E N E S S 74% of Patients Had Tumor Reduction 60 74% 40 Best Percent Change From Baseline in Target Lesions 20 10 0 0 0 0 -20 -40 -60 -80 -100 15

E V I D E N C E O F E F F E C T I V E N E S S Quick Onset of Response Following Treatment CR, PR, and uPR SD PD Onset of response Ongoing responder or SD (no PD or death) 0 1 2 3 4 5 6 7 8 9 10 Months • 8 of 10 responders have ongoing response at data cutoff • 13 of 18 patients with SD remain on treatment CR, complete response; PD, progressive disease; PR, partial response; SD, stable disease; uPR, unconfirmed partial response. 16