Working in what is arguably the hottest sector in the drug development industry, biotech researchers continue to ferret out cancer’s secrets. The premier event for those in the field is the American Society of Clinical Oncology annual meeting, taking place in Chicago from May 30 to June 1. Participants have submitted abstracts for promising therapies in advance of the conference, profiling new compounds that could lead to better outcomes for patients and bolster the health of investment portfolios. In this interview with The Life Sciences Report, LifeTech Capital’s Stephen Dunn walks us through some of the highlights.
The Life Sciences Report: Stephen, which drug class is generating the most excitement at this year’s American Society of Clinical Oncology (ASCO) conference?
Stephen Dunn: The buzz at last year’s ASCO conference surrounded the anti-PD-1 (programmed cell death protein-1) immune checkpoint inhibitor drug space. The buzz is even louder this year as more data is coming, including data on combination therapies. This space is dominated by large-cap pharmaceutical companies that are held in global portfolios. The reason for all the excitement is that the potential financial rewards of the anti-PD-1 pathway are large enough to move the needle on large-cap pharma stock prices.
In simplified terms, the PD-1 receptor pathway deactivates the immune system’s T cells, allowing the tumor cells to survive. The drug candidates are monoclonal antibodies that block the PD-1 pathway, thus allowing the T cells to remain activated and kill the tumor cells. Other companies are developing an anti-PD-L1 (programmed cell death ligand 1) monoclonal antibody that blocks the ligand side of the pathway expressed by the tumor cell, versus the PD-1 receptor found on the T cell.
The high level of excitement around this space is that immune checkpoint inhibitors may apply to a very broad range of cancer types, as both monotherapies and combination therapies. The data we are seeing so far, including recently released ASCO abstracts, also indicates the mechanism works in patients who have failed previous cancer therapies.
TLSR: Who is going to get the first FDA approval for an anti-PD-1 drug?
SD: The very first anti-PD-1 scheduled to go in front of the U.S. Food and Drug Administration (FDA) for approval is Merck & Co. Inc.’s (MRK:NYSE) MK-3475 (pembrolizumab, formerly lambrolizumab), a humanized monoclonal IgG4 antibody directed against PD-1. It has an Oct. 28 Prescription Drug User Fee Act (PDUFA) decision date based on priority review under the accelerated approval pathway for unresectable and metastatic melanoma cancer patients that have failed prior treatment with Bristol-Myers Squibb Co.’s (BMY:NYSE) Yervoy (ipilimumab). Merck also expects to file a marketing authorization application for advanced melanoma in Europe by the end of 2014.
Merck’s MK-3475 has 15 abstracts and six oral presentations at ASCO, with data for multiple indications. The most significant ASCO data for Merck was not released with the rest of the abstracts, but will be presented on June 2 as part of a late-breaking abstract session (abstract #LBA9000). The company will reveal the data on 411 advanced melanoma patients across the entire therapy spectrum, including Yervoy-failure patients, which is part of Merck’s current FDA biologics license application (BLA).
Additional evidence that MK-3475 is effective in melanoma, and that PD-1/PD-L1 receptors may be used as biomarkers, is in abstract #3005. In 135 melanoma patients treated with MK-3475, objective responses were seen as late as 64 weeks, with some conversions to complete response as late as 72 weeks. The overall response rate was 41%. The median overall survival had not yet been reached, but the one-year survival rate for PD-L1-positive patients was 84%, and 69% in PD-L1-negative patients. However, abstract #3015 showed that baseline tumor size was the strongest independent prognostic factor in patients with metastatic melanoma treated with MK-3475.