– Immunogen’s recurrent ovarian cancer drug Mirvetuximab soravtansine (IMGN853) has demonstrated promising results.
– The firm succeeded in developing and owning the drug.
– ImmunoGen is doing whatever it takes to get the drug to the patients as quickly as possible and to explore the possibility of treating other cancers with the same drug.
– The market showed extreme enthusiasm for the news.
ImmunoGen’s (IMGN) stock soared around 75% on Monday June 1, 2015 on good news about its cancer antibody drug conjugate mirvetuximab soravtansine (IMGN853) for folate receptor alpha (FRα)-positive platinum-resistant ovarian cancer. The good news was propagated following ImmunoGen’s presentation of the promising results at the 2015 American Society of Clinical Oncology (ASCO) Annual Meeting.
FRα is highly expressed on many cases of epithelial ovarian cancer and on other types of solid tumors, including endometrial cancer and some non-small cell lung cancers. Mirvetuximab soravtansine is currently being assessed for the treatment of FRα-positive, platinum-resistant ovarian cancer and for FRα-positive relapsed/refractory endometrial cancer. Additional assessments are anticipated.
Mirvetuximab soravtansine (IMGN853) is an FRα-targeting antibody drug conjugate (ADC) developed and wholly owned by ImmunoGen. It is the first and only ADC to this target to enter clinical testing, and comprises an FRα-binding antibody conjugated to DM4 — a potent cancer-cell killing agent developed by ImmunoGen specifically for use in ADCs. The antibody serves to target the DM4 specifically to FRα-positive cancer cells, which the DM4 can then kill.
The reported findings are from an ongoing Phase 1 trial. Once the recommended Phase 2 dose (RP2D) of mirvetuximab soravtansine was established during dose finding, an expansion cohort was opened to assess the safety and activity of this ADC in the treatment of patients with positive folate receptor alpha ovarian cancer that is platinum-resistance.
Twenty-two patients were included in the analysis reported. Two patients are from the dose-escalation phase of the trial and twenty patients were enrolled in the expansion cohort at the time of data cutoff for presentation (4/30/15). All the patients had FRα-positive platinum-resistant ovarian cancer and had received mirvetuximab soravtansine at the recommended Phase 2 dose (RP2D), i.e., 6.0 mg/kg, given every three weeks. All the patients had previously received taxane as well as platinum therapy. Thirteen were still on study at the time of data cutoff.
Seventeen of the 22 patients were included in the efficacy analysis; the other five patients were still on study and had not yet reached their first assessment. Nine of these 17 patients had an objective response (8 partial responses, 1 complete response) to treatment, for an overall response rate (ORR) of 53%.
The majority of adverse events reported were low grade (grade 1 or 2), with diarrhea, blurred vision, nausea, vomiting, fatigue, and abdominal pain the most common treatment-emergent events reported ( > 20% of patients).
ImmunoGen announced it was implementing a plan designed to advance mirvetuximab soravtansine as quickly as possible while recognizing the potential to benefit the greatest number of patients. It uttered its intention to initiate a Phase 2 trial in late 2015 to assess Mirvetuximab soravtansine as a single-agent treatment for patients with FRα-positive platinum-resistant ovarian cancer – a trial that could be used for registration in this patient population.
Another trial that comprises a combination of mirvetuximab soravtansine with other drugs as a potential therapy for patients with less heavily pretreated ovarian cancer is also considered. ImmunoGen will continue to explore the promising drug as a treatment for other types of FRα-positive solid tumors, including target-positive endometrial cancer.
To complement its research, ImmunoGen entered into a collaboration with the National Comprehensive Cancer Network® Oncology Research Program to investigate mirvetuximab soravtansine in additional preclinical and clinical studies.
The news is good, as ovarian cancer that recurs following the standard first-line therapy with a platinum-based regimen (e.g., carboplatin plus a taxane and potentially additional agents) has a poor prognosis. When the cancer becomes platinum-resistant, the response rates in the second- and third-line setting are around 15-20% compared to a 53% response rate from ImmunoGen’s drug. Around 21,300 new cases of ovarian cancer are diagnosed in America every year and more than 14,200 women die each year in the U.S. from recurrent ovarian cancer resistant to first-line treatment. ImmunoGen estimates that approximately 2,000-3,000 of these women have FRα-positive, platinum-resistant ovarian cancer previously treated with at least three prior lines of therapy.
The news is great for women afflicted with ovarian cancer. But that’s not all that made the stock rally 75% following the early news. From investors’ point of view, what’s really great about this news for the stock is that the drug belongs entirely to ImmunoGen. This time the firm will not be cashing some minimal royalties, as is occurring with its first approved blockbuster HER2-positive breast cancer drug, Kadcyla.
This excellent new situation emerged as a result of ImmunoGen’s decision in March 2015 to execute a $200 million non-dilutive royalty transaction with funds managed by TPG Special Situations Partners (TSSP). In return for the payment to ImmunoGen, TSSP has the right to receive 100% of the royalty revenue on Kadcyla’s® commercial sales, which would otherwise be paid to ImmunoGen by Roche, until TSSP has received a total of either $235 million or $260 million, depending on timing. After this threshold is met, if ever, ImmunoGen will receive 85% of the Kadcyla royalty revenue and TSSP will receive 15% until this revenue stream ends. The transaction yielded net proceeds to ImmunoGen of approximately $194 million.
That was a good deal reached by ImmunoGen, knowing in fact this firm has great drugs for a variety of cancers (not only ovarian cancer) in its pipeline, which could be saving the lives of many patients. Without the money, the company would have remained in a stagnant negative financial situation, in spite of the fact that its pipeline is filled with precious investigational drugs. Indeed, the stock rallied because the firm managed to develop its product and has become the sole owner of this very promising drug.
We also appreciate ImmunoGen’s wisdom in seeking the opinion of top oncology scientists before moving into further developing their drug. ImmunoGen awarded a $2-million grant to The NCCN Oncology Research Program (ORP). This grant and the resulting research will provide investigators from NCCN Member Institutions the opportunity to advance medical research that may translate into improvements in survival and quality of life for patients with cancer.
Regarding ImmunoGen drug Mirvetuximab Soravtansine, the first phase of the program will involve the establishment of an NCCN Mirvetuximab Soravtansine team comprised of relevant experts from NCCN Member Institutions to review the existing data. The group will define the study areas appropriate to enhance insight into the potential role of mirvetuximab soravtansine in the treatment of FRα-positive cancers.
The NCCN ORP draws on the expertise of investigators at NCCN Member Institutions and the NCCN Affiliate Research Consortium (ARC) to facilitate all phases of clinical research. This research is made possible by collaborations with pharmaceutical and biotechnology companies in order to advance therapeutic options for patients with cancer. The NCCN ORP will utilize the grant from ImmunoGen, to support investigator-initiated preclinical, clinical, and correlative studies of mirvetuximab soravtansine at NCCN Member Institutions and their affiliate community hospitals. To date, this research model has received more than $54 million in grants and supported 125 studies that have produced a number of publications in peer-reviewed journals.
ImmunoGen’s wants to succeed in using its state-of-the art ADC technology to bring far-reaching and safer cancer products to agonizing patients, while creating equity for its shareholders. We believe the firm is now on the right track towards realizing its dream and its shareholders dream.
We are long IMGN.
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