Keytruda's Approvals in Newer Cancer Types
Keytruda (pembrolizumab), a PD-1 inhibitor from Merck, gained approvals for several cancers relatively recently, starting with expansions beyond melanoma and lung cancer around 2017-2023. These include triple-negative breast cancer (2020), endometrial cancer (2021), and esophageal cancer (2021). In these, overall response rates (ORR) range from 18-46% in frontline or advanced settings, with median progression-free survival (PFS) of 6-10 months.[1][2]
How It Performs in Triple-Negative Breast Cancer
In KEYNOTE-522 trial for high-risk early-stage triple-negative breast cancer, Keytruda plus chemotherapy improved pathologic complete response to 64.8% (vs. 51.2% chemo alone) and extended event-free survival to 93.7% at 3 years (vs. 85%). For advanced cases in KEYNOTE-355, it boosted PFS to 9.7 months (vs. 5.6) in PD-L1-positive patients.[3][4]
Results in Endometrial Cancer
KEYNOTE-775 showed Keytruda with lenvatinib yielding ORR of 38% (vs. 15% chemotherapy) in advanced or recurrent mismatch repair proficient endometrial cancer previously treated with platinum. Median overall survival reached 18.7 months (vs. 11.9). Approvals cover MSI-high cases too, with even higher responses around 48%.[5]
Effectiveness Against Esophageal and Gastric Cancers
For esophageal squamous cell carcinoma, KEYNOTE-590 reported ORR of 47% (vs. 21% chemo) and OS of 12.4 months (vs. 9.8) with Keytruda plus platinum-fluoropyrimidine in PD-L1 CPS ≥10 patients. In HER2-negative gastric cancer (KEYNOTE-859), it improved OS to 12.9 months (vs. 11.5) and PFS to 6.9 months (vs. 5.6).[6][7]
Emerging Data in Other New Indications
Keytruda entered head and neck squamous cell carcinoma (2016, but expanded combos since), with ORR up to 19% in platinum-refractory cases. In hepatocellular carcinoma (2023 approval with Lenvima), ORR hit 36%. Ongoing trials test it in small cell lung cancer and colorectal (MSI-high subsets), showing ORR 20-40% where PD-L1 expression is high.[8][9]
What Limits Effectiveness Across New Types
Responses depend heavily on PD-L1 status, tumor mutational burden, or MSI-high/dMMR markers—only 20-40% of patients qualify and respond durably. In non-selected populations, benefits drop, with immune-related adverse events (e.g., thyroiditis, colitis) in 20-30%. No broad efficacy in "cold" tumors like pancreatic cancer.[10]
When Do Patents Expire for Keytruda?
Keytruda's main composition patent expires in 2028 in the US, but method-of-use patents extend to 2035-2036. Challenges from Amgen, Samsung Bioepis, and others target PD-1 antibodies broadly.[11]
[1]: FDA.gov, Keytruda Label (updated 2024)
[2]: Merck.com, Keytruda Approvals Timeline
[3]: NEJM, KEYNOTE-522 (2020)
[4]: NEJM, KEYNOTE-355 (2020)
[5]: NEJM, KEYNOTE-775 (2021)
[6]: Lancet Oncology, KEYNOTE-590 (2021)
[7]: JAMA Oncology, KEYNOTE-859 (2023)
[8]: FDA.gov, HCC Approval (2023)
[9]: ClinicalTrials.gov, NCT searches for pembrolizumab
[10]: ASCO Post, PD-1 Biomarker Reviews (2023)
[11]: DrugPatentWatch.com, Keytruda Patent Expiry