With accelerated approval in hand for Trodelvy (sacituzumab govitecan-hziy) to treat metastatic triple-negative breast cancer (mTNBC), Immunomedics Inc. is looking ahead to data related to the next indication for the antibody-drug conjugate (ADC) – urothelial tumors – “in the near future,” Chairman Behzad Aghazadeh told investors during a conference call.
Trodelvy was cleared well ahead of its June 2 PDUFA date for patients who have undergone at least two prior therapies. It’s the first ADC given the go-ahead specifically in relapsed/refractory mTNBC. It’s also the first anti-Trop-2 ADC to reach patients.
Morris Plains, N.J.-based Immunomedics set the wholesale acquisition cost for a single-use 180-mg vial at $2,012, which equates to $16,096 per 21-day cycle for a 70-kg person. Based on a median five-month treatment duration, as the company maintained in its phase II study known as IMMU-132-01, the price amounts to about $113,000 per course of therapy – about 20% lower than Padcev (enfortumab vedotin-ejfv), the Nectin-4 targeted ADC from Tokyo-based Astellas Pharma Inc. and Seattle Genetics Inc., of Bothell, Wash., approved in late 2019 for metastatic urothelial cancer. Wainwright analyst Robert Burns liked the setup, reiterating his buy rating and raising the 12-month price target to $60 from $34. Shares (NASDAQ:IMMU) closed at $26.18, up $4.19, or 19%.
Chief Commercial Officer (COO) Brendan Delaney said the company “tried to assume a duration of therapy similar to what the clinical experience has been,” hence the five-month choice. “As far as the dosing per patient, you're looking at the average patient [and] it's difficult to pin down, because of the weight base, but it's around four vials per patient for the typical patient.” More will be known as doctors get more experience with the drug in the real world, he said.
In the phase II mTNBC effort, Trodelvy yielded an overall response rate of 33.3% (95% confidence interval [CI]: 24.6, 43.1) and a median duration of response of 7.7 months (95% CI: 4.9, 10.8), as determined by local assessment, in 108 adult TNBC patients who had previously received a median of three prior systemic therapies in the metastatic setting (range: 2-10). Immunomedics noted that continued approval may be contingent on verifying clinical benefit in the confirmatory phase III experiment called Ascent, recently halted by the independent data safety monitoring committee due to compelling evidence of efficacy across multiple endpoints.
Guggenheim analyst Michael Schmidt noted on the conference call that patients in the phase II experiment “were predominantly in the fourth-line setting,” and asked what that might mean as Trodelvy becomes widely available. Delaney said Immunomedics is “going to promote the drug in line with what the approved indication is, and that’s after two prior therapies. As far as trying to translate the clinical trial experience, there is an urgent push within, I would say, the oncology [and] the breast cancer world[s] to try to use the product in the labeled indication as soon as possible. I think early on in the real world, we will see a bolus of patients who have been waiting for this drug. That could be in fourth line, that could be in fifth line.” The company will be “moving very quickly to establishing a strong market share in the third-line setting,” he said. “As far as any other use in addition to that, I can't really comment on how that will play out.”
The approval, Cowen analyst Phil Nadeau said in a report, “marks a major milestone for Immunomedics, and ushers in a new era as a commercial company,” while laying to rest “lingering concerns over a delay due to the recently disclosed manufacturing issues” – a relief to many investors. Trodelvy’s label carries a black box warning for severe neutropenia and severe diarrhea, but neither Nadeau nor Jefferies analyst Chris Howerton seemed concerned. The latter said in his report that the “language is modest and physicians are well-equipped to manage those adverse events [AEs].” He predicted rapid adoption in mTNBC.
Wainwright’s Burns weighed in about the black box, too, noting that that at the European Society for Medical Oncology meeting in 2019, Scott Tagawa, an associate professor of hematology and oncology at Weill Cornell Medicine, said that “most oncologists are comfortable with granulocyte-macrophage colony-stimulating factor, the principal agent used to treat neutropenia,” and the side effect is typically transient anyway. Only 2.8% of patients in the phase II study discontinued treatment due to an AE. The drug’s “meaningful incremental efficacy relative to chemotherapy outweighs these potential side effects,” he said.
COO Delaney said that, “given the current COVID-19 environment to which we are all adjusting, we have invested in a set of tools and technology infrastructure that allows us to conduct remote detailing and enable virtual video conferences with health care providers.” As for supply, Aghazadeh said the firm has enough on hand “to address the need in the immediate near term” and is “in a position to start launching this product promptly.”
About a year ago, Immunomedics inked a license agreement with Everest Medicines II Ltd., of Shanghai, to develop, register and commercialize the drug in much of Asia outside of Japan. The firm banked an up-front payment of $65 million and collects $60 million more based on the FDA approval.