Follistatin-like 3 (FSTL3) is a prognostic marker and a potential therapeutic target in ovarian cancer

We are pleased to announce the publication of our latest study, by Chauvin et al., in the Journal of Experimental & Clinical Cancer Research entitled “FSTL3 is a biomarker of poor prognosis and associated with immunotherapy resistance in ovarian cancer”.

Why it matters:

• Analysis of patient samples revealed that elevated FSTL3 in ascites strongly correlates with shorter survival in high-grade serous ovarian cancer.

• In mouse models, serum FSTL3 levels reflected tumor growth, and overexpression of FSTL3 promoted a fibrotic, immune-excluded tumor microenvironment.

• Tumors overexpressing FSTL3 exhibited marked resistance to combined immunotherapy and CHK1 inhibitor treatment, revealing a potential mechanism of immunotherapy failure.

Take-home message:

• FSTL3 emerges as a secreted stromal biomarker for prognosis and treatment response in ovarian cancer, and may represent a therapeutic target to overcome immunotherapy resistance.

We finally made it!

After a string of (let’s just say forgettable) attempts, the Pépin Lab has finally done it—our artwork made it onto the X page of Plasmidsaurus! https://t.co/wOMsoIdbD0" / X

This triumph is powered by the unmatched devotion of Karine de Mattos, whose borderline pathological persistence turned determination into everlasting victory. When greatness called, she brought in the brilliant Josephine to transform this dream into an outstanding accomplishment destined to inspire future generations of Pépin Lab creators.

Marie Meinsohn is the Candlepin Bowling queen of 2024

Last December, the Pépin lab celebrated 2024 with their annual candlepin bowling + pizza party.

After two hours of bowling, well-earned pizza!

If the manager of Sacco's Bowl Haven reads this: Don’t worry, we put back the trophy on its shelf.

Cancer-associated mesothelial cells are regulated by the anti-Müllerian hormone axis

We’re excited to finally share our newest study by Maeva Chauvin et al. in CellReports on the role of the AMH-AMHR2 paracrine axis in ovarian cancer, overturning 40 years of research in the field and Identifying a potential new immunotherapy target for ovarian cancer: cancer-associated mesothelial cells.

One the reasons that treating this disease has been so challenging is that tumors often become resistant to chemotherapies, and generally respond poorly to immunotherapies. While much of the research on overcoming resistance and efforts to develop new therapies have focused on the cancer cells, it has often ignored the many other cell types of the tumor. Indeed, cancer cells have the ability to reprogram the cells around them to nurture the tumor and help evade the patient’s immune system. One of these cells is the mesothelial cell, which represents the point of first contact of ovarian cancer cells during peritoneal metastasis.  In this study, we show how cancer cell reprogram these mesothelial cells into cancer-associated-mesothelial cell, which then promote the growth of the tumor. Importantly we identify one of the signals, a hormone called Anti-Müllerian hormone, which is used by cancer cells reprogram and control mesothelial cells. We show that disrupting this signal slows the growth of the tumor and helps the immune system overcome some of the tumor’s defenses suggesting it may represent a new target in ovarian cancer.

We demonstrate how cancer cells reprogram normal mesothelial cells into cancer-associated mesothelial cells (CAMC) that have a pro-tumoral function. At the heart of this reprogramming is the reactivation of an important developmental hormone signal, in the form of the anti-Mullerian hormone (AMH), and its receptor AMHR2. While AMHR2 had long been assumed to be expressed by cancer cells, we found that instead cancer-associated mesothelial cells are the tumor cell types that carry this receptor, and that ovarian cancer cells produce its ligand, AMH. We reveal that cancer cells use AMH to control cancer-associated mesothelial cells, by modulating their production of growth factors that promote tumor growth and cytokines that help cloak the tumor from the immune system. This new understanding presents exciting possibilities for therapeutic strategies that aim to neutralize the AMH signal from cancer cells or target the AMHR2 on mesothelial cells to potentially inhibit tumor growth and restore immune response.

Congrats to Philippe Godin for SSR presentation award

As we recover from a successful SSR2023 meeting, we have a some great news to share, our own Postdoc Fellow Philippe Godin did a terrific job with his talk about AAV9-AMH based permanent contraceptive development for the cat, sharing some exciting new preliminary data of complete efficacy when given to kittens and winning the first prize for his poster!

A single dose of an AMH-based viral-vectored therapy provides safe and durable contraception in female domestic cats

Boston, MA (June 6, 2023)

Members of the Pépin lab and collaborators are proud to announce that their latest paper is now available in Nature Communications. In this study we explore a completely new way to achieve long-term contraception in the female domestic cat.

But why do we need to sterilize cats? Current estimates on the number of unowned, free roaming domestic cats worldwide are in the hundreds of millions. These free-roaming cats are more likely to contract infectious diseases and to be involved in traffic accidents, both factors contributing to an abbreviated, more traumatic life. Furthermore, cats are generalist predators that can prey on a variety of species of small birds, mammals, and reptiles. They are thought to be responsible for the death of approximately two billion birds per year in the US alone and have contributed to the extinction of over 63 species to date. This effect is especially damaging when domestic cats are introduced to areas where native species lack natural defenses against mammalian predators.

Why can’t we just spay and neuter? The current standard of care in feline population control is through surgical sterilization. In the female, this is performed through the surgical removal of the ovaries under general anesthesia. The procedure is expensive and requires veterinary expertise, specialized medical supplies, anesthetic and analgesic drugs, and postoperative care. Trap-Neuter-Return (TNR) programs are implemented with the intent of putting a stop to uncontrolled reproduction of unowned, free-roaming cats in overpopulated areas. However, this approach cannot scale to control the reproduction of the hundreds of millions of unowned felines worldwide because it not efficient enough and there are simply not enough veterinarians to perform all these surgeries.

A single dose, non-surgical sterilant is critically needed to overcome the shortcomings of surgical approaches and to address the significant ethical, economic, and environmental concerns associated with overpopulation of unowned free-roaming domestic cats.

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In this first of its kind study, Vansandt and collaborators demonstrated the safety and efficacy of a viral-vectored delivery of an anti-Mullerian hormone (AMH) transgene in female domestic cats.

The therapy is based on the natural inhibitory properties of AMH on the growth of ovarian follicles. Following a single intramuscular injection, treated females maintained AMH levels over 100 times the levels naturally found in this species for over two years, resulting in the complete prevention of ovulation.

Following introduction of a fertile male into the colony, all control females became pregnant and delivered kittens while none of the six females treated with the therapy conceived. More than 1,200 hours of video recordings were analyzed to monitor male-female interactions during this period. Four treated females did not even allow a single breeding by a male during the two four-month long mating trials included in this study.

Suppressing ovarian follicle development and ovulation did not significantly affect important reproductive hormones such as inhibins and estrogens. However, as expected of a contraceptive preventing ovulation, progesterone secretion was lower in treated cats as they experienced fewer luteal phases. Most importantly, there were no adverse effects observed in any of the treated animals, demonstrating that at the doses tested, the gene therapy was safe and well tolerated.

The study plan includes adoption of the cats into private homes and follow-up of health and well-being over the next several years. Ongoing studies are looking at the safety and efficacy of this approach in female kittens. We are also working to optimize the therapy to make it more efficient and to reduce cost.

Philippe Godin, DMV, PhD

This publication is the result of more than seven years of collaborative effort between the Pépin laboratory, the Center for Conservation and Research of Endangered Wildlife (CREW) at the Cincinnati Zoo and Botanical Garden, and the Horae Gene Therapy Center at the University of Massachusetts Chan Medical School. Major funding for this research was provided by the Michelson Prize & Grants, a program of The Michelson Found Animals Foundation, the Joanie Bernard Foundation, and the department of Surgery of the Massachusetts General Hospital.

To read more about this story:

Science. Hello kitty, goodbye kittens? Gene therapy spays cats without surgery

The Harvard Gazette. Birth control for cats?

The Atlantic. Sterilizing Cats, No Surgery Required

The New York Times. Gene Therapy May Offer Birth Control for Cats

CNN. Cat contraception using gene therapy could help with population control, study says

National Geographic. Not spayed. Not neutered. This birth control for cats doesn't require surgery

Sciences et Avenir (français). La stérilisation des chats révolutionnée par la thérapie génique

Radio-Canada (français). Une technique non chirurgicale permet de stériliser les chattes

El País (español). Probada con éxito una inyección para esterilizar gatas de forma permanente

Repurposing drugs with AMHR2 agonist activity as contraceptives

In a manuscript published in PNAS, Li et al. screened a repurposed drug library and identify small molecule agonists of the AMHR2 receptor, the first step in the development of an entirely new class of female contraceptives.

Women are born with a fixed number of oocytes encased in a single layer of pregranulosa cells forming primordial follicles. They constitute the ovarian reserve. Once activated, primordial follicles grow until they reach ovulation or die through apoptosis. The depletion of the primordial follicle pool triggers menopause.

Most existing hormonal contraceptives block ovulation of large antral follicles by acting on the hypothalamic-pituitary-gonadal axis, and share side-effects such as migraine, weight gain, diminished libido, breast tenderness, nausea, and increased cardiovascular and cancer risks. Since the developmental progression from a primordial follicle to an ovulated egg takes several months, and their activation and early growth is independent of gonadotropins and steroids, controlling primordial follicles activation could represent a new mechanism of contraception.

Anti-Mullerian hormone (AMH) is the only known paracrine factor capable of inhibiting the activation of primordial follicles. We have previously demonstrated complete contraception of adult female mice following the administration of an AAV9 gene therapy inducing superphysiological concentrations of AMH. Treatment with AMH resulted in a significant decrease in the number of activated follicles population and suppression of cycling.

Nevertheless, the use of recombinant AMH for long term contraception in women remains impractical. To address this concern, and accelerate the development of a new class of contraceptives based on this mechanism of action, we developed a screening methodology to identify small molecules that can recapitulate the contraceptive properties of AMH, by agonizing its receptor AMHR2. In this manuscript, we show that Sp600125, CYC-116, gandotinib, and ruxolitinib can function as AMHR2 agonists in vitro, and can inhibit primordial follicle activation and preantral follicle maturation in vivo. These findings open the way to use or modify these molecules to develop new contraceptives, with unique attributes, such as suppression of cycling with maintenance of estrogens, and potential applications in maintenance of the ovarian reserve during chemotherapy or aging.

Single cell RNAseq reveals pathways of follicle quiescence regulated by MIS in the ovary

In a manuscript published in PNAS, Meinsohn et al. show that AMH/MIS inhibits granulosa cells, ovarian surface epithelial cells, and ovarian stromal cells in neonatal mouse and rat ovaries. The transcriptional programs regulated in these cell types were identified by scRNAseq, and validated by qPCR and RNAish. In addition to inhibiting proliferation, genes associated with stemness (Lgr5, Aldh1a1) were repressed in the surface epithelium, which also shared perturbation of similar gene networks observed in the granulosa cells (Id2, Id3, Smad6, etc.). In contrast, stromal cell types, which express little to no MISR2 receptor had a unique response to treatment, which may be related to disruption of cell-cell communication with their granulosa and epithelial neighbours, including IGF and BMP/TGFb signalling. Surprisingly we identified few perturbation in germ cells, suggesting the follicle quiescence is mainly driven by regulatory programs in the granulosa cells. Futhermore, we characterized a new follicular phenotype in response to MIS treatment in which oocytes excaped repression and grew, but granulosa cells failed to mature in tandem, giving rise to mismatched oocyte-follicle development. This repressive effect of MIS on preantral granulosa cell maturation may complement the inhibition of primordial follicle activation to maintain ovarian quiescence. Furthermore we identified regulatory networks, such as immediate-early genes which were associated with granulosa cell quiescence in control females, and further activated when treated with MIS.

Press releases describing the potential clinical applications can be found here:

MIS hormone shown to suppress ovarian follicle development

New understanding of ovarian follicle development may lead to novel reproductive therapies

New syngeneic mouse model of ovarian cancer

Thanks to a fruitful collaboration with the Weinberg Laboratory at the Whitehead Institute, we are pleased to have played a part in describing these new ovarian cancer models, that were derived from transformed Fallopian tube epithelium, bear human-relevant mutational genotypes, and can grow in immuno-competent C57BL6 mice. These will be an invaluable tool to test novel immunotherapies, and already allowed us to identify Follistatin overexpression as a mechanism of immunotherapy resistance!

The paper is out in Cancer Discovery.