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UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

 

FORM 8-K

 

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934

 

Date of Report (Date of earliest event reported): January 10, 2020

 

MERSANA THERAPEUTICS, INC.

(Exact name of registrant as specified in its charter)

 

Delaware   001-38129   04-3562403
(State or other jurisdiction of
incorporation) 		  (Commission File Number)   (IRS Employer
Identification No.)

 

840 Memorial Drive 
Cambridge, MA 02139		    
Cambridge, MA   02139
(Address of principal executive offices)   (Zip Code)

 

(Registrant’s telephone number, including area code): (617) 498-0020

 

Not Applicable

(Former name or former address, if changed since last report)

 

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

 

¨  Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

 

¨  Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

 

¨  Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

 

¨  Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

 

Securities registered pursuant to Section 12(b) of the Act:

 

Title of each class Trading Symbol(s) Name of each exchange on which
registered
Common Stock, $0.0001 par value MRSN The Nasdaq Global Select Market

 

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

 

Emerging growth company  x

 

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.  x

 

 

 

 

 

Item 7.01Regulation FD Disclosure

 

Mersana Therapeutics, Inc. (the “Company”) from time to time presents and/or distributes to the investment community at various industry and other conferences slide presentations to provide updates and summaries of its business. A copy of its current corporate slide presentation (the “Presentation”) is furnished as Exhibit 99.1 to this Current Report on Form 8-K. The Company undertakes no obligation to update, supplement or amend the materials attached hereto as Exhibit 99.1.

 

The information contained in this Item 7.01, including Exhibit 99.1 attached hereto, is being furnished and shall not be deemed “filed” for the purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), and shall not be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as expressly set forth by specific reference in such filing.

 

Item 8.01Other Events.

 

On January 10, 2020, the Company issued a press release providing an update on the Company’s business and announcing the Company’s strategic priorities and goals for 2020 and beyond. The Company’s press release is attached as Exhibit 99.2 to this Current Report on Form 8-K and is incorporated herein by reference.

 

Item 9.01 Financial Statements and Exhibits.

 

(d) Exhibits

 

Exhibit No.   Description
     
99.1   Corporate slide presentation of Mersana Therapeutics, Inc., dated January 10, 2020
99.2   Press Release by Mersana Therapeutics, Inc., on January 10, 2020

 

 

 

 

EXHIBIT INDEX

 

No.   Description
     
99.1   Corporate slide presentation of Mersana Therapeutics, Inc., dated January 10, 2020
99.2   Press Release by Mersana Therapeutics, Inc., on January 10, 2020

 

 

 

 

SIGNATURES

 

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

 

    MERSANA THERAPEUTICS, INC. 
   
    By: /s/ Brian DeSchuytner
    Brian DeSchuytner
Senior Vice President, Finance & Product Strategy 

 

Date: January 10, 2020

 

 

 

 

Exhibit 99.1

 

Accelerating ADC Innovation …because patients are waiting January 2020

 

 

Legal Disclaimer This presentation contains “forward - looking” statements within the meaning of federal securities laws . These forward - looking statements are not statements of historical facts and are based on management’s beliefs and assumptions and on information currently available to management . Forward - looking statements include information concerning the Company’s business strategy and the design, progression and timing of its clinical trials . Forward - looking statements generally can be identified by terms such as “expects,” “anticipates,” “believes,” “could,” “seeks,” “estimates,” “intends,” “may,” “plans,” “potential,” “predicts,” “projects,” “should,” “will,” “would” or similar expressions and the negatives of those terms . The Company’s operations involve risks and uncertainties, many of which are outside its control, and any one of which, or combination of which, could materially affect its results of operations and whether the forward - looking statements ultimately prove to be correct . Factors that may materially affect the Company’s results of operations and whether these forward - looking statements prove to be correct include, among other things, that preclinical testing may not be predictive of the results or success of ongoing or later preclinical or clinical trials, that the development of the Company’s product candidates and new platforms will take longer and/or cost more than planned and that the identification of new product candidates will take longer than planned, as well as those listed in our Annual Report on Form 10 - K filed on March 8 , 2019 , with the Securities and Exchange Commission (“SEC”) and subsequent SEC filings . Except as required by law, the Company assumes no obligation to update these forward - looking statements publicly, or to update the reasons actual results could differ materially from those anticipated in the forward - looking statements, even if new information becomes available in the future . Copies of the Company’s Annual Report on Form 10 - K and our other SEC filings are available by visiting EDGAR on the SEC website at http : //www . sec . gov . 2

 

 

Mersana is Poised for a Transformational 2020 3 1 Excluding Brazil 2 Cash, Cash Equivalents, and Marketable Securities as of September 30, 2019 XMT - 1536 • First - in - class asset • Clinically - Validated • Wholly - Owned 1 • Fast - to - market strategy On Track for Near - Term Proof of Concept First - In - Class Pipeline • Addressing unmet patient needs • Fast - to - market strategies 1 IND and 2 Development Candidates in 2020 Innovative Platforms • Multiple partnering opportunities • Efficient product engines DolaLock (Dolaflexin, Dolasynthen) and Immunosynthen Strong Foundation • Experienced team • Runway to mid - 2021 $112M in Cash 2 +$15M Credit Facility

 

 

2020 Will Be a Data Rich Year 4 o Establish proof of concept o Rapid dose escalation o Select first development candidate o Progress into IND - enabling studies 2019 ACCOMPLISHMENTS 2020 PRIORITIES x Established proof of activity & tolerability x Established preclinical proof of concept x Advanced through discovery x Advanced through discovery XMT - 1536 IND Candidate (XMT - 1592) Immunosynthen Development Candidate DolaLock Development Candidate

 

 

We are Leveraging our Novel ADC Platforms to Generate Differentiated Product Candidates 5 ADC Program Target Indication Platform Discovery Preclinical P1 Dose Escalation P1 Proof of Concept P2/Pivotal Study XMT - 1536 NaPi2b Ovarian Cancer NSCLC Adenocarcinoma Dolaflexin XMT - 1592 NaPi2b NSCLC Adenocarcinoma Ovarian Cancer Dolasynthen To Be Named B7 - H4 Multiple Solid Tumors Dolaflexin or Dolasynthen To Be Named Multiple Multiple Solid Tumors Immunosynthen To Be Named Multiple Undisclosed Dolasynthen To Be Named Multiple Undisclosed Dolaflexin Platform Collaborators Multiple Multiple Undisclosed Dolaflexin ASN004 5T4 Undisclosed Dolaflexin

 

 

Efficacy without severe neutropenia, neuropathy, or ocular toxicity DolaLock Dolaflexin Improved therapeutic index vs. other platforms Dolasynthen Homogenous & Customizable Platform Immunosynthen Systemic administration with targeted immuno - stimulatory effect Innovative and Highly Differentiated ADC Technologies and Platforms 6 • Controlled bystander effect • Selectively toxic to rapidly dividing cells • Not a PgP substrate • Induces immunogenic cell death • DolaLock payload • Polymer scaffold • DAR ~10 - 12 • Excellent drug like properties • DolaLock payload • Synthetic scaffold • Site - specific • Precise DAR (2 - 24) • Novel STING agonist • Complete regression with one dose in multiple models • Limited effect on systemic cytokines DAR = Drug - to - antibody ratio STING = Stimulator of Interferon Genes

 

 

XMT - 1536: First - in - Class Dolaflexin ADC Targeting NaPi2b

 

 

Leader in Targeting NaPi2b, an Ideal and Validated ADC Target • Broadly expressed in ovarian cancer and NSCLC adenocarcinoma ⁃ No detectable expression in squamous NSCLC ⁃ Limited expression in healthy tissues • NaPi2b is a lineage marker (not an oncogene) that transports phosphate into the cell ⁃ The presence of EGFR and KRAS mutations in NSCLC adenocarcinoma correlates with more frequent expression of NaPi2b • Proprietary biomarker assay can distinguish across low, medium, and high expression ⁃ Correlation between biomarker expression and response in preclinical and clinical settings ⁃ Developing companion diagnostic for use in registration enabling study 8 In Ovarian PDX Models, only tumors with an H - score above cutoff had a tumor response >50% Change in Tumor Volume H - score 290 H - score 0 Increasing H - score Mosher et al, AACR - NCI - EORTC International Conference, October 2017 Mitchell et al, AACR - NCI - EORTC International Conference, October 2019 D’Archangelo, et al. Abstract 194P ESMO 2014

 

 

XMT - 1536: Advancing Through Proof - of - Concept Studies in Ovarian Cancer and NSCLC Adenocarcinoma 9 Encouraging Clinical Activity Well - Tolerated • Confirmed responses and prolonged stable disease in heavily pretreated and biomarker unselected patients reported at ASCO 2019 • Expansion cohorts ongoing in ovarian cancer and NSCLC adenocarcinoma • MTD not yet reached • Dose escalating to 52 mg/m 2 • No severe toxicities commonly seen with other ADCs: neutropenia, ocular toxicities, or peripheral neuropathy • Transient AST elevation without associated changes in bilirubin 1 Excluding Brazil ASCO 2019 Poster #3010; Phase 1 dose escalation study of XMT - 1536, a novel NaPi2b - targeting antibody - drug conjugate (ADC), in patients (pts) with solid tumors likely to express NaPi2b; June 2019, Data Cutoff May 10, 2019 • Clinically - validated target • Fast - to - market strategy • Wholly - owned 1 First - in - Class Multiple Data Read Outs Expected in 2020

 

 

XMT - 1536 was Well - Tolerated with Most AE’s Grade 1 - 2 10 ClinicalTrials.gov: NCT03319628 Dosing: Q3 weeks DL 4A 20 mg/m 2 (0.54 mg/kg) N=9 DL 5A 30 mg/m 2 (0.81 mg/kg) N=8 DL 6A 36 mg/m 2 (0.97 mg/kg) DL 1 3 mg/m 2 (0.081 mg/kg) N=1 DL 2 6 mg/m 2 (0.162 mg/kg) N=1 DL 3 12 mg/m 2 (0.324 mg/kg) N=7 DL 4 20 mg/m 2 (0.54 mg/kg) N=6 DL 5 30 mg/m 2 (0.81 mg/kg) N=4 DL 6 40 mg/m 2 (1.08 mg/kg) N=1 DL 7A 43 mg/m 2 (1.2 mg/kg) Presented at ASCO Dosing: Q4 weeks DL 8A 52 mg/m 2 (1.4 mg/kg) Ongoing No Severe Toxicities Associated with Other ADC Platforms such as Neutropenia, Ocular Toxicities, or Peripheral Neuropathy Data Presented at ASCO with a Data Cutoff of May 10, 2019 Treatment Related Adverse Events in ≥10% of Patients

 

 

XMT - 1536 Showed Activity in Heavily Pretreated Patients, Unselected for NaPi2b 11 Data Presented at ASCO with a Data Cutoff of May 10, 2019 Response evaluable All Completed Dose Levels (OC and NSCLC Patients), N=26 Clinically Meaningful Treatment Duration > 16 weeks Clinical Activity at Doses of 20mg/m 2 and Above* Response evaluable Based on objective responses and duration of treatment *As measured by RECIST, version 1.1 Treatment Duration (weeks)

 

 

XMT - 1536: Significant Progress Since ASCO 2019 in Maximizing Patient Benefit and Charting Path to Registration 12 • Initiated expansion cohorts in earlier line, more homogeneous populations Earlier, More Homogeneous Patient Population Higher Dose Opportunity for Biomarker Selection • Correlating H - score and efficacy in anticipation of patient selection • Collecting archival and fresh tissue to confirm concordance • Cleared 36 and 43 mg/m 2 with primarily Grade 1 and Grade 2 AEs with no severe neuropathy, neutropenia or ocular toxicities • Increased expansion cohort dose to 43 mg/m 2 • Currently evaluating 52 mg/m 2 FAST - TO - MARKET REGISTRATION STRATEGY

 

 

XMT - 1536: Path to Pivotal Study in High Unmet Need Indications 13 Population Dose Current Standard of Care ORR: 4 - 12% mPFS: 3 - 4 mos mOS: 9 - 12 mos • Prior treatment with a platinum doublet and PD - 1/L1 inhibitor • Prior TKIs if targetable mutation • Up to 2 prior lines of cytotoxic therapy • Adenocarcinoma histology • 36 mg/m 2 dose initiated in Aug 2019 • 43 mg/m 2 dose initiated in Dec 2019 ORR: 14 - 23% mPFS: 3 - 4 mos mOS: 9 - 12 mos Dose Escalation Data in 1H 2020 • Late stage platinum - resistant ovarian cancer • Late stage recurrent NSCLC adenocarcinoma • Evaluating 52 mg/m 2 Ovarian Cancer Expansion Data in 1H & 2H 2020 • 1 - 3 prior lines in platinum resistant • 4 prior lines regardless of platinum status • High grade serous histology • 36 mg/m 2 dose initiated in Aug 2019 • 43 mg/m 2 dose initiated in Dec 2019 NSCLC Adeno Expansion Data in 1H and 2H 2020 Investigational Agent

 

 

XMT - 1592 is a Dolasynthen ADC Targeting NaPi2b

 

 

XMT - 1592 Shows Four - Fold Greater Efficacy in Lung Tumor Model 15 2X Tumor Exposure of Payload 0 7 14 21 28 35 42 49 56 63 70 0 500 1000 1500 2000 Days on study M e a n T u m o r V o l u m e S E M ( m m 3 ) Vehicle XMT-1536 @ 0.1 mg/kg [2.1 mg/kg mAb] XMT-1592 @ 0.1 mg/kg [3.0 mg/kg mAb] 0.1 mg/kg payload XMT-1592 @ 0.025 mg/kg [0.75 mg/kg mAb] XMT - 1536 XMT - 1592 After single, equal dose of 0.05 mg/kg by payload 4X Greater Activity in Lung PDX 0 7 14 21 28 0 50 100 150 Days Post Dosing n g / g T u m o r T i s s u e P l a s m a T u m o r L i v e r L u n g S p l e e n K i d n e y 0 10000 20000 30000 40000 A U C l a s t Our Success with NaPi2b Makes it an Ideal Target for Evaluation of the Clinical Differentiation of Dolasynthen

 

 

Leveraging NaPi2b Experience for Rapid Dose Escalation of XMT - 1592 16 2021 Solidify NaPi2b Leadership Leveraging insights from XMT - 1536 Biomarker Investigators Antibody Payload Patient Populations Target 2020 2020 2021 Inform Product Engine File IND Initiate Dose Escalation Achieve MTD Clinical Proof of Differentiation

 

 

First - in - Class B7 - H4 ADC Progressing into IND - Enabling Studies

 

 

B7 - H4 Expression Ideally Suited for a DolaLock ADC • B7 - H4 is expressed on both tumor cells and immunosuppressive tumor - associated macrophages (TAMs) ⁃ Limited expression in normal tissues • A DolaLock ADC targeting B7 - H4 can exert its effect through multiple mechanisms of action: ⁃ Uptake by tumor cells and direct cytotoxicity ⁃ Uptake by TAMs to release payload in the tumor microenvironment ⁃ Free payload can activate dendritic cells and a secondary immune response • Expression in PD - L1 negative tumors, provides a potential fast to market opportunities (e.g., triple negative breast cancer) 18 TUMOR CELL CATABOLIZES ADC Immune Response T CELL CHECKPOINT BLOCKADE AF - HPA Diffusion Bystander Effect DENDRITIC CELL ACTIVATION BY AF - HPA BYSTANDER KILLING IMMUNOGENIC CELL DEATH (ICD) ICD B7 - H4 B7 - H4 B7 - H4 B7 - H4 TUMOR KILLING TUMOR KILLING TUMOR - ASSOCIATED MACROPHAGE CATABOLIZES ADC T CELL PRIMING IND - enabling studies in 2020

 

 

Immunosynthen Development Candidate in 2020

 

 

Immunosynthen: Strong Rationale for a STING Agonist ADC Approach ADCs are suited to overcome limitations of free agonist: ⁃ Targeted delivery reduces toxicity liabilities ⁃ Improved pharmacokinetics ⁃ Accessibility to metastatic sites ⁃ No restriction on tumor type, location or size 20 Nature Reviews Cancer 4, 11 – 22 (2004) Adaptive Immunity (slow response) Stepping on the gas pedal of the immune system (e.g. STING agonists) Releasing the brakes of the immune system (e.g. checkpoint inhibitors) Innate Immunity (rapid response)

 

 

0 7 14 21 28 0 50 100 150 200 250 Days on Re-challenge Study M e a n T u m o r V o l u m e + / - S E M ( m m 3 ) Immunosynthen ADCs Show In Vivo Activity Against Multiple Targets and Immune Memory 21 0 7 14 21 28 35 42 49 56 63 0 250 500 750 1000 Days on study M e a n T u m o r V o l u m e + / - S E M ( m m 3 ) 10/10 tumor free ADC Against Target 1 0.09 mg/kg 0.12 mg/kg 0 7 14 21 28 35 42 49 56 63 70 77 0 500 1000 1500 2000 Days on study M e a n T u m o r V o l u m e + / - S E M ( m m 3 ) 0.12 mg/kg 0.09 mg/kg ADC Against Target 2 5.0 mg/kg 5.0 mg/kg 0 7 14 21 28 35 0 200 400 600 800 Days on Study M e a n T u m o r V o l u m e + / - S E M ( m m 3 ) 0.035 mg/kg 0.035 mg/kg ADC Against Target 3 6/9 tumor free Tumor re - challenge of 6 tumor - free mice diABZI STING agonist (all doses as STING agonist payload mg/kg) Control ADC Vehicle Targeted ADC Control Mice Tumor Re - challenge Target 3 Re - Challenged Mice

 

 

Immunosynthen ADC Activates STING Pathway and Induces Marked Immune Cell Infiltration in Tumors 22 Cytokine expression (qPCR on FFPE samples) 0 5 10 15 20 25 12H 72H mCXCL10 0 0.4 0.8 1.2 1.6 12H 72H mIFN β 0 2 4 6 12H 72H mIL - 6 12 H 12 H 12 H 72 H 72 H mCXCL10 mIL - 6 mIFNβ Vehicle Targeted ADC Control ADC 72 H CD45 Immunohistochemistry Immune cell infiltration Vehicle 12 hrs. 72 hrs. Targeted ADC Control ADC CD45 Immunohistochemistry 12 hrs. 72 hrs. Data shown for Immunosynthen ADC for Target 1 After single dose of 0.09 mg/kg by STING agonist payload

 

 

Limited Induction of Serum Cytokines In Vivo by Immunosynthen ADC Despite Extended Plasma Exposure 23 CXCL10 IL - 6 CXCL1 RANTES (CCL5) 0 20 40 60 80 0 1000 2000 3000 4000 Hours 0 20 40 60 80 0 5000 10000 15000 20000 25000 Hours 0 20 40 60 80 0 2000 4000 6000 Hours 0 20 40 60 80 0 1000 2000 3000 4000 5000 Hours 0 20 40 60 80 0 50 100 150 200 Hours TNF - α IFNγ pg/mL 0 5 10 15 10 100 1000 10000 100000 Plasma Concentration Time (Days) C o n c e n t r a t i o n [ n g / m l ] M e a n + / - S D Total Antibody Conjugated Drug Extended plasma exposure to Immunosynthen ADC does not result in extended exposure to systemic cytokines ~ 100 x ~ 15 x pg/mL 0 20 40 60 80 0 2000 4000 6000 Hours ~ 6 x ~ 21 x ~ 60 x ~ 74 x Circulating Plasma Levels ADC (All doses by STING agonist payload mg/kg) diABZI STING agonist 5.0 mg/kg Control ADC 0.12 mg/kg Targeted ADC 0.09 mg/kg Vehicle Analysis of Serum Cytokine Levels by Luminex Assay Data shown for Immunosynthen ADC for Target 1

 

 

On Track to Select First Immunosynthen ADC Development Candidate in 2020 24 Payload Molecule Drug Load Per Scaffold Charge Balance Aqueous Solubility Bioconjugation Antibody x Identified proprietary STING payload specifically designed for ADCs x Demonstrated efficacy across multiple targets in a variety of models x Confirmed tolerability in multidose exploratory NHP study o Finalize proprietary STING ADC scaffold (linker, DAR, method and site of bioconjugation) o Select first Immunosynthen ADC from current targets and leads Expect to disclose data package in 2H 2020

 

 

2020: A Transformational Year for Mersana with Multiple Data Readouts 25 2020 Goals & Anticipated Milestones XMT - 1536 • Report dose escalation in 1H 2020 • Report interim data from OC and NSCLC expansion cohorts in 1H 2020 • Report more mature data from expansion cohorts in 2H 2020 XMT - 1592 • File IND and initiate clinical study in 1H 2020. Achieve rapid dose escalation B7 - H4 • Advance IND - enabling studies • Disclose development candidate data package in 2H 2020 Immunosynthen • Select first development candidate • Disclose development candidate data package in 2H 2020 Product Engine • Continue to leverage proprietary platforms to expand pipeline Corporate • Proactively evaluate potential for strategic collaborations that maximize value

 

 

Positioned to Create Value for Patients and Shareholders 26 • First - in - class NaPi2b ADC • Completion of proof - of - concept studies in 2020 • Fast - to - market registration strategy XMT - 1536 • Extends NaPi2b leadership • Fast to clinical validation of preclinical differentiation XMT - 1592 • First - in - class B7 - H4 and Immunosynthen ADCs • Targeting high unmet medical needs Pipeline • Dolaflexin, Dolasynthen (DolaLock) • Immunosynthen (Novel STING Agonist) • Efficient product engines with multiple partnership opportunities Platforms • Strong team • Strong balance sheet Fundamentals

 

 

 

 

 

Exhibit 99.2

 

Mersana Therapeutics Announces Pipeline Updates and 2020 Strategic Priorities and
Milestones

 

XMT-1536 On Track to Demonstrate Proof of Concept in Both Ovarian and Non-Small Cell Lung
Cancer with Multiple Data Readouts Expected Throughout 2020

 

XMT-1536 Expansion Study Dose Increased; Dose Escalation Study Continues

 

Next Clinical Candidate, XMT-1592, a Dolasynthen ADC Targeting NaPi2b, to Initiate

First-in-Human Study in First Half of 2020

 

B7-H4, a First-In-Class ADC Target, Named as Next Pipeline Candidate with Initiation of

IND-Enabling Studies in 2020

 

Immunosynthen Platform Expected to Deliver First STING Agonist ADC Development Candidate in
Second Half of 2020

 

CAMBRIDGE, Mass., January 10, 2020 -- Mersana Therapeutics, Inc. (NASDAQ:MRSN), a clinical-stage biopharmaceutical company focused on discovering and developing a pipeline of antibody-drug conjugates (ADCs) targeting cancers in areas of high unmet medical need, today provided a pipeline update and announced its strategic priorities and anticipated milestones for 2020. Anna Protopapas, President and CEO of Mersana Therapeutics, will review these business updates in a presentation at the upcoming 38th Annual J.P. Morgan Healthcare Conference on Thursday, January 16, 2020.

 

“XMT-1536, a first-in-class NaPi2b-targeting Dolaflexin ADC, is nearing proof of concept and we expect to report important data from both the dose escalation and expansion portions of the study throughout 2020,” said Anna Protopapas. “XMT-1536 has shown confirmed responses and durable stable disease in biomarker unselected and heavily pretreated patients. XMT-1536 continues to be both active and well-tolerated at higher doses, and we have increased the dose in both the expansion and dose escalation portions of the study.”

 

“We have also made significant progress in leveraging our differentiated ADC platforms to build an exciting pipeline of candidates. XMT-1592, a NaPi2b-targeted ADC based on our new Dolasynthen platform, aims to extend our leadership in NaPi2b-directed therapies while also clinically validating the differentiated profile that our Dolasynthen platform has shown preclinically,” continued Anna Protopapas. “In addition, we are advancing a first-in-class ADC candidate targeting B7-H4, an antigen with a unique expression profile in the tumor and its microenvironment. Finally, we have developed a STING agonist ADC platform, Immunosynthen, with encouraging preclinical efficacy and tolerability data across multiple targets and anticipate selection of a development candidate later this year. 2020 has the potential to be a transformational year for Mersana as we progress in our efforts to develop novel therapeutics for patients with high unmet need.”

 

 

 

 

Corporate Updates and 2020 Goals

 

Progress in Phase 1 Study of XMT-1536

 

·Dose increased to 52 mg/m2 in escalation portion of the XMT-1536 Phase 1 study. XMT-1536 was well tolerated by patients at the 43 mg/m2 once-every-four-week dosing regimen. No patients experienced dose limiting toxicities, and the dose has been well-tolerated with primarily Grade 1 and Grade 2 treatment-related adverse events. The Company has initiated evaluation of a 52 mg/m2 once-every-four-week dose escalation cohort and expects to report dose escalation data in the first half of 2020.

 

·Dose increased to 43 mg/m2 in the expansion portion of the XMT-1536 Phase 1 study; enrollment of both ovarian cancer and non-small cell lung cancer (NSCLC) adenocarcinoma patients continues. Patients in the expansion study, currently on the 36 mg/m2 once-every-four-week dose regimen, will remain at that dose. Newly enrolled patients will receive a 43 mg/m2 once-every-four-week regimen. The Company expects to present interim data from the expansion study in the first half of 2020 and to be able to report more mature data in the second half of 2020.

  

Selection of Next Clinical Candidate XMT-1592

 

·XMT-1592, a NaPi2b-targeting Dolasynthen ADC, selected as next clinical candidate, further extending Mersana’s leadership position in NaPi2b and ADC innovation. Mersana’s Dolasynthen platform retains the proprietary auristatin DolaLock payload with controlled bystander effect plus the added benefits of site-specific conjugation, precise drug-to-antibody ratio, and even greater hydrophilicity for further enhanced drug-like properties and tumor exposure. In preclinical studies, Dolasynthen has shown four times greater efficacy in a lung tumor model in comparison to Dolaflexin, a platform that has already shown success when targeted to NaPi2b. The Company plans to evaluate the clinical differentiation of Dolasynthen by leveraging its experience in NaPi2b to rapidly and efficiently progress XMT-1592 through dose escalation, which it expects to initiate in the first half of 2020.

  

Advances Across Discovery Pipeline

 

·Initiating IND-enabling studies of a first-in-class B7-H4 ADC candidate. B7-H4 is expressed on both tumor cells and tumor-associated macrophages (TAMs). A B7-H4 ADC delivering a DolaLock payload has been shown in preclinical studies to exert a direct cytotoxic effect via uptake by tumor cells, as well as deliver additional payload release in the tumor environment through binding and catabolism in B7-H4-expressing TAMs. It has been shown that the DolaLock payload can activate dendritic cells and induce immunogenic cell death, with the potential to provide a secondary, immune-based anti-tumor effect in addition to the primary cytotoxic effect. The Company expects to disclose its development candidate and supporting data in the second half of 2020.

 

·Immunosynthen platform on track to deliver a STING agonist ADC development candidate in 2020. The Company has developed a novel STING agonist ADC platform and has generated preclinical data across multiple targets and models showing complete regression of tumors in vivo with a single, well-tolerated dose, consistent with increased cytokine expression and immune cell infiltration within the tumor. The Company expects to finalize the platform design and target evaluation and select its first STING agonist ADC development candidate in the second half of 2020. The Company also expects to disclose additional preclinical data at scientific meetings throughout 2020.

 

 

 

 

Upcoming Events

 

·The Company will review these achievements and milestones during its upcoming presentation at the 38th Annual J.P. Morgan Healthcare Conference in San Francisco, CA on Thursday, January 16, 2020 at 9:00 am PT.

  

About Mersana Therapeutics

 

Mersana Therapeutics is a clinical-stage biopharmaceutical company using its differentiated and proprietary ADC platforms to rapidly develop novel ADCs with optimal efficacy, safety and tolerability to meaningfully improve the lives of people fighting cancer. Mersana’s lead product candidate, XMT-1536, is in a Phase 1 proof-of-concept clinical trial in patients with tumors expressing NaPi2b, including ovarian cancer and NSCLC adenocarcinoma. Mersana’s second product candidate targeting NaPi2b-expressing tumors, XMT-1592, is an ADC created using Mersana’s customizable and homogenous Dolasynthen platform. The Company’s early stage programs include a B7-H4 targeting ADC, as well as a STING agonist ADC developed using the Company’s Immunosynthen platform. In addition, multiple partners are using Mersana’s platforms to advance their ADC pipelines.

 

Forward-Looking Statements


This press release contains “forward-looking” statements within the meaning of federal securities laws. These forward-looking statements are not statements of historical facts and are based on management’s beliefs and assumptions and on information currently available to management. Forward-looking statements include information concerning the Company’s business strategy and the design, progression and timing of its clinical trials. Forward-looking statements generally can be identified by terms such as “aims,” “anticipates,” “believes,” “could,” “expects,” “seeks,” “estimates,” “intends,” “may,” “plans,” “potential,” “predicts,” “projects,” “should,” “will,” “would” or similar expressions and the negatives of those terms. Forward-looking statements represent management’s beliefs and assumptions only as of the date of this press release. The Company’s operations involve risks and uncertainties, many of which are outside its control, and any one of which, or combination of which, could materially affect its results of operations and whether the forward-looking statements ultimately prove to be correct. Factors that may materially affect the Company’s results of operations and whether these forward-looking statements prove to be correct include, among other things, that preclinical testing may not be predictive of the results or success of ongoing or later preclinical or clinical trials, that the development and testing of the Company’s product candidates and new platforms will take longer and/or cost more than planned and that the identification of new product candidates will take longer than planned, as well as those listed in the Company’s Annual Report on Form 10-K filed on March 8, 2019, with the Securities and Exchange Commission (“SEC”) and subsequent SEC filings. Except as required by law, the Company assumes no obligation to update these forward-looking statements publicly, or to update the reasons actual results could differ materially from those anticipated in the forward-looking statements, even if new information becomes available in the future.

 

 

 

 

Contact:

 

Investor & Media Contact
Sarah Carmody, 617-844-8577

scarmody@mersana.com