Episode 51: ImmunoGen

In this episode of Petri Dish Perspectives: Biotech Unleashed, we dive into the 40+ year journey of ImmunoGen, a company that refused to give up on one of the most complex and misunderstood technologies in oncology: antibody-drug conjugates (ADCs).

From its early days as a Dana-Farber spinout to decades of scientific setbacks, market skepticism, and near-collapse moments, ImmunoGen’s story is anything but linear. We explore how the company survived the “ADC dark ages,” built foundational technology through partnerships with giants like Genentech and Roche, and ultimately made the bold pivot from platform provider to full-fledged drug developer.

If you want to understand how long it really takes to build a platform technology, why being early can be both a curse and a competitive advantage, and how persistence shapes success in biotech, this episode is for you.

🎧 Listen now, stay curious, and don’t forget to subscribe for new episodes every Thursday!

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Transcript

Hello and welcome to Petri Dish Perspectives, the podcast where we geek out about science and the companies shaping the future of healthcare. I’m your host, Manead, and I’m a PhD scientist by training, biotech storyteller by choice. With every new episode released on Thursday, my goal is to deliver digestible pieces of information on healthcare companies under 30 mins. 

Forty-three years. That’s how long it took. From a university spinout in 1981 to a $10 billion acquisition by AbbVie in 2024, this is the story of ImmunoGen—a company that endured decades of failed trials, skeptical investors, and a technology the industry repeatedly abandoned. ImmunoGen bet everything on antibody-drug conjugates, or ADCs, long before they became one of the hottest areas in oncology. They went public in 1989, saw their stock soar to over $40, then collapse to pennies. They survived catastrophic clinical failures that wiped out half their value overnight. And somehow, they came back. This is one of biotech’s most remarkable persistence stories.

Quick disclaimer, I give full credit to the original articles cited in the references in the transcript!

Grab a coffee or tea, settle in, and let’s jump in!

The Original Vision: Turning Antibodies into Guided Missiles

To understand this story, you have to go back to 1981 in Boston, at the Dana-Farber Cancer Institute. At the time, monoclonal antibodies were seen as “magic bullets”—precision tools that could target cancer cells. But there was a fundamental problem: antibodies alone didn’t kill cancer effectively. They could find tumors, but they couldn’t destroy them. 

ImmunoGen wasn't just another biotech spin-off; it was the brainchild of Dr. Mitchel Sayare, a PhD biochemist who saw a fundamental flaw in how we treated cancer. While he was an assistant professor at UConn, Sayare watched the industry rely on what he called 'shotgun' chemotherapy—drugs that killed the tumor but devastated the patient. His 'Aha!' moment? The realization that monoclonal antibodies shouldn't just be diagnostics—they should be delivery vehicles. He co-founded ImmunoGen in 1981 to build the first 'guided missiles' for oncology. He spent the next three decades as CEO.

Mitchel saw an opportunity in that gap. What if antibodies could be turned into delivery vehicles? What if you could attach a highly potent cytotoxic drug to an antibody and send it directly to cancer cells? That was the founding vision: targeted cancer therapy using what would later be called antibody-drug conjugates.

Why Early ADCs Failed — And Almost Took ImmunoGen With Them

Being first meant making every mistake. In the 1980s and 1990s, ImmunoGen struggled to make ADCs work. Early attempts using standard chemotherapy drugs like doxorubicin failed because they weren’t potent enough. The company pivoted to more toxic compounds, including modified versions of ricin, but those approaches also failed due to delivery challenges. Eventually, they focused on maytansinoids—extremely potent microtubule inhibitors—but even then, the chemistry was incredibly complex. The antibody had to bind precisely, the linker had to remain stable in the bloodstream, and the payload had to activate only inside cancer cells. Solving all three simultaneously took decades, and during that time, the broader industry began to lose confidence in ADCs as a viable therapeutic strategy.

Going Public in the Wilderness Years

In 1989, ImmunoGen went public, raising about $14 million. At the time, they had no approved products—just a platform and a vision. Their stock climbed during the biotech boom, reaching over $40 in 2000, but the subsequent crash and broader skepticism around ADCs sent it tumbling. The field itself nearly collapsed when early ADCs failed commercially and clinically, reinforcing doubts about the entire approach. Through all of this, ImmunoGen persisted, continuing to refine its science even as investor confidence eroded.

Cracking the Code: Payloads, Linkers, and Precision Targeting

What ultimately differentiated ImmunoGen was its deep focus on the core mechanics of ADCs. An effective ADC requires three components to work in harmony: the antibody for targeting, the linker for stability and controlled release, and the payload for cell killing. ImmunoGen developed expertise particularly in linker chemistry and payload design, including highly potent maytansinoids like DM1 and DM4. These compounds were far more potent than traditional chemotherapy, enabling effective tumor killing with minimal dosing. The company’s innovations in both cleavable and non-cleavable linkers helped ensure that drugs would remain stable in circulation and only release their payload once inside cancer cells, a key breakthrough that made modern ADCs viable.

Surviving Through Big Pharma: The Roche and Genentech Years

ImmunoGen survived its most difficult years through strategic partnerships. Collaborations with companies like Genentech, part of Roche, allowed it to license its technology while others funded expensive clinical trials. These deals provided steady revenue and validation of the platform but came with a trade-off: ImmunoGen did not control development or commercialization. It became a behind-the-scenes enabler of innovation rather than the face of it.

Kadcyla: Proof the Platform Actually Works

That changed in 2013 with the approval of Kadcyla, an ADC developed by Genentech using ImmunoGen’s technology. It was the first successful ADC for a solid tumor and demonstrated clear survival benefits in HER2-positive breast cancer. Kadcyla went on to become a blockbuster drug, validating decades of work in ADC development. However, ImmunoGen only received royalties, highlighting the limitations of its partnership-driven model.

From Platform Player to Drug Developer

In 2016, ImmunoGen made a strategic pivot under new leadership. The company decided to move beyond being a platform provider and instead develop its own drugs. This shift meant taking on greater risk but also offered the potential for significantly greater reward. The company focused on mirvetuximab soravtansine, an ADC targeting folate receptor alpha in ovarian cancer, marking its transition into a fully integrated biotech company.

The transition did not go smoothly. In 2019, the pivotal Phase 3 trial for mirvetuximab failed to meet its primary endpoint, causing ImmunoGen’s stock to drop by half in a single day. It was a defining crisis. Years of investment appeared to collapse overnight, and many questioned whether the company could recover.

Redesigning for Success

Instead of abandoning the program, ImmunoGen reanalyzed the data and identified a critical insight: the drug was most effective in patients with high expression of folate receptor alpha. The company redesigned its clinical strategy, narrowed its patient population, and developed a companion diagnostic to better identify responders. This precision approach led to new trials that demonstrated meaningful clinical benefit.

Elahere: The Moment ImmunoGen Became Real

In 2022, mirvetuximab—now called Elahere—received accelerated FDA approval, marking ImmunoGen’s first fully owned commercial product. Subsequent data confirmed its ability to improve survival, leading to full approval in 2024. After more than four decades, ImmunoGen had successfully brought its own drug to market, transforming itself from a platform company into a commercial-stage biotech.

The $10 Billion Exit: Why AbbVie Made Its Move

Shortly after Elahere’s success, in February 2024, AbbVie finalized its landmark $10.1 billion acquisition of ImmunoGen, a strategic play to command a leading share of the high-growth antibody-drug conjugate (ADC) market. The deal is anchored by the flagship oncology asset ELAHERE (mirvetuximab soravtansine-gynx), the first targeted therapy to demonstrate a transformative survival benefit in platinum-resistant ovarian cancer. By integrating ImmunoGen’s specialized technology, AbbVie not only secures a critical revenue stream to offset losses from legacy products like Imbruvica but also significantly expands its solid tumor pipeline with next-generation candidates such as IMGN-151 and pivekimab sunirine. This acquisition effectively transforms AbbVie into a global ADC powerhouse, bridging the gap between its hematological roots and a future defined by precision solid tumor therapeutics.

Too Early, Too Complex, Too Risky?

The company’s journey was not without criticism. ImmunoGen was arguably too early to the ADC space, bearing the cost of early failures. Its reliance on partnerships limited its financial upside, and certain clinical decisions—such as trial design—delayed progress. These challenges highlight the difficulties of pioneering complex technologies in biotechnology.

Lessons from ImmunoGen

Several lessons emerge from this story. Platform technologies often require decades to mature. Partnerships can sustain innovation but may limit long-term value capture. Failures, when analyzed correctly, can lead to better strategies. And above all, persistence is a critical competitive advantage in biotechnology.

What’s Next For ImmunoGen?

Today, ADCs are one of the fastest-growing areas in oncology. Pharmaceutical companies are investing heavily in next-generation payloads, linkers, and targets, building on the foundation that ImmunoGen helped establish. The field continues to expand, with potential applications extending beyond cancer into other areas of medicine.

Following the $10.1 billion acquisition, the immediate focus for ImmunoGen, now a core pillar of AbbVie’s oncology strategy, is the aggressive label expansion of ELAHERE from platinum-resistant to platinum-sensitive ovarian cancer (PSOC). This effort reached a major milestone at the SGO 2026 Annual Meeting in April, where late-breaking Phase 2 data (IMGN853-0420) demonstrated a robust 62.7% confirmed objective response rate for the Elahere-carboplatin combination, positioning the ADC to move into earlier lines of therapy. Beyond Elahere, the integration aims to leverage AbbVie’s global scale to commercialize the next-generation pipeline, including pivekimab sunirine, which saw a BLA submission in late 2025 for the rare blood cancer BPDCN, and the biparatopic ADC IMGN-151, currently in dose-escalation trials. By combining ImmunoGen's established Targeted Antibody Payload (TAP) platform with AbbVie’s deep portfolio of checkpoint inhibitors and PARP inhibitors, the merged entity is working to define a new "post-chemotherapy" standard in solid tumors through rational combination regimens.

Outro

ImmunoGen’s story is a reminder that breakthroughs in biotechnology are rarely immediate. They are the result of decades of iteration, failure, and persistence. From its founding in 1981 to its acquisition in 2024, the company’s journey reflects the long and uncertain path of innovation. In the end, ImmunoGen proved that belief in science—combined with endurance—can transform even the most uncertain ideas into reality.

This has been Petri Dish Perspectives. I’m Manead. Thanks for listening. See you next Thursday. Good bye.

References

1. www.wikipedia.org
2. https://www.abbvie.com/immunogen.html 
3. https://www.fiercebiotech.com/ 
4. https://finance.yahoo.com/ 
5. https://endpoints.news/