In the race toward the approval of cancer immunotherapy targeting PD-1 and PDL-1 (programmed death protein 1 and programmed death ligand 1), MPDL3280A by Roche Holding AG (RHHBY 1.80%) may have just pulled ahead.
Researchers of Roche's drug for non-small-cell lung cancer announced a 23% overall response rate for tumor shrinkage and a 26% response rate in smokers, a notoriously difficult-to-treat patient population. The sample size for this study was small, only 53 patients, although Roche's prior study on MPDL3280A included 140 patients and showed a 21% rate of tumor shrinkage for a cohort of lung, melanoma, and kidney cancers.
Targeted therapies revolutionize cancer treatments
Oncology has long been striving to find more immunotherapy agents. Cancer treatments are notoriously non-specific, with chemotherapy and radiation often non-curative and causing devastating side effects. Immunotherapy, targeting specific proteins expressed by tumor cells, has yielded some truly incredible blockbuster therapies: Gleevec by Novartis (NVS 1.26%), Vesanoid by Roche, Herceptin by Genentech/Roche, Avastin by Genentech/Roche, etc.
PD-1 and PDL-1 are partner proteins that work together to cloak cancer cells from a patient's immune system. Targeting these proteins allow the cancer cells to be unmasked for a patient's T-cells to destroy. Roche's MPDL3280A targets PD-L1 while rivals Bristol-Myers Squibb (BMY 1.44%) and Merck (MRK 0.20%) have targeted PD-1.
A race for this blockbuster market
Bristol-Myers started off the field of PD-1 immunotherapy last summer with nivolumab, showing a 40% response rate for melanoma. It also reported an more than 80% reduction in tumor size in nearly a third of advanced melanomas over 12 weeks when used in combination with Yervoy. The speed and magnitude of that response quickly put Bristol-Myers as the front runner in the field with a Yervoy/nivolumab combination drug. However, similar to Roche's study, Bristol-Myers' study only included 52 patients.
Merck quickly came out with lambrolizumab, or MK-3475, reporting a 35% response rate and FDA designation as a breakthrough therapy, expediting the path to approval. Roche followed with a study on MPDL3280A, showing a 21% response rate for a mixed patient population of lung cancers, melanomas, and kidney cancers.
With an estimated $35 billion field on the line, the company that develops the first blockbuster PD-1 cancer drug will establish primacy in what could become one of the biggest drug class in history. Only 3% of cancer treatments currently include an immunotherapy. This number is expected to skyrocket to 60% use by 2023 according to some analysts. With that, investors can only imagine how the stocks may similarly rise.
Keeping tally
Bristol-Myers is currently recruiting for phase 3 trials for its nivolumab/Yervoy combination drug, with fast-track status for melanoma, lung cancer, and kidney cancer . Roche is continuing its phase 2 trials with MPDL3280A for non-small-cell lung cancer and also in phase 1 trials for a Avastin-combo for solid tumors and a Zelboraf-combo for melanoma Merck's lambrolizumab will be launching phase 3 trials this quarter for both melanoma and non-small-cell lung cancer. It will also be initiating phase 2 trials comparing lambrolizumab to the standard chemotherapy for melanoma and phase 1 trials for breast, bladder and head & neck cancer
While all promising, these drugs have shown statistical significance in trials, but have yet to prove clinical significance -- that is, whether or not tumor shrinkage will translate into improved patient survival. Studies are beginning to compare these agents to the current standard of care, but results have yet to be published. Until these therapies can prove their worth both in clinical practice and against current standard treatments, investors and the medical community alike may need to stay in the stands for this race.
