Mersana Inventory: I Keep A Small Watch Merchandise Place In MRSN


Naeblys / iStock via Getty Images

“It is possible to forget our past, but our past will not forget us.” Francesca Marciano, Casa Rossa

Today we visit Mersana Therapeutics (MRSN) for the first time since we published this article about the company last February. Like most small biotech stocks, 2021 was not a good year for the company or its shareholders. The company has several potential test milestones on the horizon and has also recently made some significant purchases from a beneficial owner. A full analysis follows below.

Company overview

Mersana Therapeutics is based in Cambridge, MA, outside of Boston. This clinical-stage biotech company focuses on the development of antibody-drug conjugates [ADCs] for cancer patients with unmet needs. The stock currently trades just over $ 6 per share and has an approximate market capitalization of $ 470 million.

Recent events / pipeline:

Overall, 2021 was not a good year for the company and its shareholders. The stock suffered a major slump in September after Mersana released preliminary data from an expansion cohort in an early-stage study for ovarian cancer patients for its lead compound, upifitamab rilsodotin (UpRi), that revealed a significant percentage of side effects for participants in the study. A company spokesman said at the time that the “larger dataset provides important observations to support the potential of UPLIFT as a registration strategy and to inform next steps in the UpRi development plan”.

However, as measured by the stock, which quickly fell a third on the news, investors weren’t as optimistic. Stocks also slumped to begin 2021 when disappointing early-stage results were released from the same program.

Mersana Therapeutics

Source: company website

The company has two main assets under development, UpRi and XMT-1592. Both were developed to improve the existing effectiveness of ADC. Current ADCs release their cytotoxic payload in target cells. However, the drug is often able to penetrate cell membranes, penetrate into neighboring cells and possibly kill them, regardless of whether these cells are carcinogenic or not. This effect is called “bystander-killing”. This is effective when bystander cells are carcinogenic, but toxic when the cytotoxic drug can penetrate neighboring healthy cells. Mersana’s candidates are designed to only hit target cells and control the bystander effect for safer, more effective cancer therapy.

The company’s primary asset is Upifitamab Rilsodotin, or UpRi. This candidate is a top-rated ADC targeting NaPi2b and developed on the company’s Dolaflexin platform. It is being investigated in UPLIFT, a single-arm registration study in patients with platinum-resistant ovarian cancer. In the summer of 2020, UpRi was granted fast-track status by the FDA for “platinum-resistant high-grade serous ovarian cancer who have received up to three previous systemic lines of therapy or patients who have received four previous systemic lines of therapy independent of platinum status”.

The company plans to enroll approximately 180 patients in this pivotal study and started it in the third quarter of this year. Another Phase 3 study of maintenance therapy with UpRi monotherapy in platinum-sensitive ovarian cancer is expected to begin in the second quarter of this year.

This candidate will also be evaluated in a phase 1/2 “UPGRADE” umbrella study in combination with other ovarian cancer therapies. Interim results from this study should be released sometime in the second half of this year.

The company’s secondary pipeline asset is XMT-1592. This is an ADC created using Mersana’s proprietary Dolasynthen platform. XMT-1592 incorporates the same proprietary NaPi2b antibody and powerful Auristatin DolaLock payload with controlled bystander effect as Upifitamab-Rilsodotin (UpRi). It also includes the additional functions of site-specific bioconjugation, precise DAR, and homogeneous DAR distribution. The company initiated a Phase 1 dose escalation study of XMT-1592 in spring 2020 in patients with tumors likely to express NaPi2b. The company has other potential candidates in earlier stages of development but they are not relevant to this analysis.

Analyst comment & balance sheet

Since November, the company has received five purchase ratings from analyst firms such as Wedbush and Robert W. Baird. The price targets on offer range from $ 17 to $ 26 per share. JPMorgan does not share its optimism as they reiterated their hold rating and target price of $ 11 on November 20th. A director representing Bain Capital bought just over $ 10 million in shares on December 29th and 30th to close 2021. The company now owns just over seven percent of the shares in Mersana. The company ended the first nine months of 2021 with just over $ 190 million in cash and marketable securities on its balance sheet, after posting a net loss of $ 45.5 million for the quarter. The company also recently opened a new $ 100 million line of credit with Oxford and Silicon Valley Bank. Of this, $ 60 million is available and up to an additional $ 40 million can be made available, depending on whether the company hits milestones.


Mersana has a potentially fascinating development approach and platform. The pipeline has some targets, analyst support is solid, and recent beneficial owner purchases are encouraging. However, the study results were not considered positive up to this point. In addition, Mersana’s previous lead candidate (XMT-1522 for HER2 breast cancer) was abandoned in early 2019 due to safety, efficacy and market issues. Given that I hold a small “watch item” position with MRSN, the stock and company are in “show me” territory at this point in their development journey.

“The only appeal of the past is that it is the past.” – Oscar Wilde, The Picture of Dorian Gray

Bret Jensen is the founder and author of articles for the Biotech Forum, Busted IPO Forum and Insiders Forum

You might also like

Leave A Reply

Your email address will not be published.