Mersana’s innovative platforms are a highly efficient product engine that is building a robust discovery pipeline for us and our partners. Our ADCs in preclinical and clinical trials are first-in-class molecules that target multiple tumor types with high unmet medical need. We believe our platforms create an opportunity for our ADCs to demonstrate improved safety and efficacy relative to those developed using first-generation technology. Our lead asset, upifitamab rilsodotin (UpRi), is a first-in-class Dolaflexin ADC targeting NaPi2b that is being studied in UPLIFT, a single-arm registrational trial in patients with platinum-resistant ovarian cancer, and in UPGRADE, a Phase 1/2 umbrella trial evaluating UpRi in combination with other ovarian cancer therapies. Mersana’s early-stage programs include XMT-1660, a Dolasynthen ADC targeting B7-H4, and XMT-2056, a STING-agonist ADC developed using the Company’s Immunosynthen platform and targeting a novel epitope of human epidermal growth factor receptor 2 (HER2). In addition, multiple partners are using Mersana’s platforms to advance their ADC pipelines.

ADC Program	Target	Indication	Platform	Phase
upifitamab rilsodotin (UpRi)*	NaPi2b	Platinum-Resistant Ovarian Cancer	Dolaflexin	P2 Pivotal Study
upifitamab rilsodotin (UpRi)*	NaPi2b	Platinum-Resistant Ovarian Cancer	Dolaflexin	P1 Dose Escalation
upifitamab rilsodotin (UpRi)*	NaPi2b	Recurrent Platinum-Sensitive Ovarian Cancer Maintenance	Dolaflexin	P3
XMT-1592*	NaPi2b	Ovarian Cancer NSCLC Adenocarcinoma	Dolasynthen	P1 Dose Escalation
XMT-1660	B7-H4	Multiple Solid Tumors	Dolasynthen	Preclinical
XMT-2056	HER2	Undisclosed	Immunosynthen	Preclinical
XMT-2068	Tumor-Associated Antigen	Undisclosed	Immunosynthen	Discovery
XMT-2175	Tumor-Associated Antigen	Undisclosed	Immunosynthen	Discovery
Multiple Programs	Undisclosed	Undisclosed	Immunosynthen	Preclinical
Multiple Programs	Undisclosed	Undisclosed	Immunosynthen Dolasynthen Dolaflexin	Discovery
Multiple	Multiple	Undisclosed	Dolasynthen	Discovery
Multiple	Multiple**	Undisclosed	Dolaflexin	P1 Dose Escalation
ASN004	5T4	Undisclosed	Dolaflexin	P1 Dose Escalation

*NaPi2b antibody used in UpRi (formerly XMT-1536) is in-licensed from Recepta Biopharma. Recepta has rights to commercialize UpRi in Brazil.
**EMD Serono is an affiliate of Merck KGaA