June 22, 2020
ImmunoGen Presents Preclinical Data on IMGN151 at Virtual AACR Annual Meeting

Next Generation FRα-Targeting ADC Engineered to Maximize Potential Clinical Benefit for Patients with Lower FRα Expression

Potent Anti-Tumor Activity Exhibited in Ovarian Cancer and Other Tumor Types Regardless of FRα Expression Level

WALTHAM, Mass.--(BUSINESS WIRE)--Jun. 22, 2020-- ImmunoGen, Inc. (Nasdaq: IMGN), a leader in the expanding field of antibody-drug conjugates (ADCs) for the treatment of cancer, today announced preclinical data for its next generation anti-folate receptor alpha (FRα) ADC, IMGN151, which is being investigated in tumors with a broad range of FRα expression. The findings were shared via poster presentation at the virtual American Association for Cancer Research (AACR) Annual Meeting II.

“Engineered to include multiple antibody and linker-payload innovations, IMGN151 targets tumors with a broad range of FRα expression,” said Eric Westin, MD, Vice President of Clinical Development and Translational Sciences at ImmunoGen. “IMGN151 demonstrated enhanced anti-tumor activity in both in vitro and in vivo preclinical models, with complete regression of human tumor xenograft models induced in those with high, medium, and low levels of FRα expression. Based on these data, we look forward to exploring IMGN151 in the clinic in multiple FRα-positive epithelial malignancies, including ovarian, endometrial, triple negative breast, and non-small cell lung cancer.”

Poster Presentation, Abstract 2890

IMGN151 comprises an asymmetric, bivalent, biparatopic antibody targeting two independent epitopes of FRα, linked to a highly potent maytansinoid derivative, DM21, via a cleavable peptide linker with enhanced stability, longer half-life, and increased bystander activity. The average drug per antibody ratio is 3.5. IMGN151 activity was characterized against cell lines and xenograft models with a wide range of FRα expression and compared to mirvetuximab soravtansine (IMGN853). Cell lines and xenograft models originated from ovarian, endometrial, breast, and cervical cancer.

Key findings include:

  • The protease-cleavable linker deployed in IMGN151 improves stability and ADC exposure; as compared to IMGN853, pharmacokinetic studies in cynomolgus monkeys showed increased ADC half-life by 60 hours and conjugate exposure in vivo by 40%.
  • The IMGN151 biparatopic format boosted antibody binding events and DM21 payload delivery in tumor cell lines; the increased payload delivery and greater membrane permeability of DM21 enhanced bystander killing activity.
  • In vitro, IMGN151 was more active against FRα-positive cell lines, with the most pronounced effect in cells with low to medium levels of FRα.
  • In vivo, IMGN151 demonstrated better activity over IMGN853 against low and medium levels of FRα, and equivalent activity to IMGN853 against FRα high tumors with lower effective dose; all tested doses were well tolerated.

Additional information can be found at


IMGN151 is a next-generation ADC, designed to address the unmet needs of cancer patients with tumor types expressing lower levels of folate receptor alpha (FRα). IMGN151 comprises an asymmetric, bivalent, biparatopic antibody targeting two independent epitopes of FRα, linked to a highly potent maytansinoid derivative, DM21, via a cleavable peptide linker with enhanced stability, longer half-life, and increased bystander activity.


ImmunoGen is developing the next generation of antibody-drug conjugates (ADCs) to improve outcomes for cancer patients. By generating targeted therapies with enhanced anti-tumor activity and favorable tolerability profiles, we aim to disrupt the progression of cancer and offer our patients more good days. We call this our commitment to “target a better now.”

Learn more about who we are, what we do, and how we do it at


This press release includes forward-looking statements based on management's current expectations. These statements include, but are not limited to, ImmunoGen’s expectations related to: the occurrence, timing, and outcome of potential pre-clinical, clinical, and regulatory events related to ImmunoGen’s product candidates; and the presentation of pre-clinical and clinical data on ImmunoGen’s product candidates. For these statements, ImmunoGen claims the protection of the safe harbor for forward-looking statements provided by the Private Securities Litigation Reform Act of 1995. Various factors could cause ImmunoGen’s actual results to differ materially from those discussed or implied in the forward-looking statements, and you are cautioned not to place undue reliance on these forward-looking statements, which are current only as of the date of this release. Factors that could cause future results to differ materially from such expectations include, but are not limited to: the timing and outcome of ImmunoGen’s pre-clinical and clinical development processes; the difficulties inherent in the development of novel pharmaceuticals, including uncertainties as to the timing, expense, and results of pre-clinical studies, clinical trials, and regulatory processes; ImmunoGen’s ability to financially support its product programs; risks and uncertainties associated with the scale and duration of the COVID-19 pandemic and resulting impact on ImmunoGen’s industry and business; and other factors more fully described in ImmunoGen’s Annual Report on Form 10-K for the year ended December 31, 2019 and other reports filed with the Securities and Exchange Commission.

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Courtney O’Konek

FTI Consulting
Robert Stanislaro

Source: ImmunoGen, Inc.



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