Pembrolizumab (Keytruda) 100mg/4ml Injection: Efficacy, Dosing, and Clinical Use

Pembrolizumab (Keytruda) is an immune checkpoint inhibitor used to treat various cancers, including advanced non-small cell lung cancer (NSCLC), melanoma, and colorectal cancer. The 100mg/4ml injection is a formulation relevant for weight-based and fixed dosing strategies, with recent research exploring its effectiveness, safety, and cost implications.

Dosing Strategies and Clinical Effectiveness

• Pembrolizumab is commonly administered at 200mg every 3 weeks, but studies show that a 100mg fixed dose (approximately 2 mg/kg for average-sized patients) is similarly effective for advanced NSCLC, with no significant difference in progression-free or overall survival compared to the higher dose (Low et al., 2021).
• Early phase studies established that doses as low as 2 mg/kg every 3 weeks achieve full target engagement and robust antitumor activity in multiple solid tumors (Patnaik et al., 2015; Low et al., 2021).
• The 100mg dose may offer substantial cost savings without compromising efficacy or safety, making it a viable option, especially in resource-limited settings (Low et al., 2021).

Safety and Adverse Effects

• Pembrolizumab is generally well tolerated. Common side effects include fatigue, rash, nausea, and immune-mediated reactions such as pneumonitis and colitis (Chuk et al., 2017; Patnaik et al., 2015; Low et al., 2021).
• No significant increase in severe immune-related toxicities was observed with the 100mg dose compared to the 200mg dose (Low et al., 2021).

Regulatory Approvals and Indications

• Pembrolizumab is approved for multiple indications, including metastatic melanoma, NSCLC, and MSI-H/dMMR colorectal cancer, with dosing regimens tailored to cancer type and patient characteristics (Team, 2021; Chuk et al., 2017).
• Regulatory decisions have been influenced by the durability of response and favorable risk-benefit profile (Chuk et al., 2017).

Dosing, Efficacy, and Cost Comparison

Dose & Regimen	Indication	Efficacy (PFS/OS)	Safety Profile	Cost Implications	Citations
100mg every 3 weeks	Advanced NSCLC	Similar to 200mg	Comparable	Significant savings	(Low et al., 2021)
200mg every 3 weeks	NSCLC, Melanoma, CRC	Standard of care	Well tolerated	Higher cost	(Team, 2021; Chuk et al., 2017; Patnaik et al., 2015)
2 mg/kg every 3 weeks	Multiple solid tumors	Full target engagement	Well tolerated	Weight-based	(Patnaik et al., 2015; Low et al., 2021)

Figure 1: Comparison of pembrolizumab dosing, efficacy, safety, and cost.

Results Timeline

• 2015
  • 1 paper: (Patnaik et al., 2015)- 2016
  • 1 paper: (Elassaiss-Schaap et al., 2016)- 2017
  • 2 papers: (Chuk et al., 2017; Tawbi et al., 2017)- 2018
  • 1 paper: (Ritzel et al., 2018)- 2019
  • 2 papers: (Haight et al., 2019; Chung et al., 2019)- 2020
  • 5 papers: (Brastianos et al., 2020; Ohji et al., 2020; Powell et al., 2020; Blauvelt et al., 2020; Cohen et al., 2020)- 2021
  • 2 papers: (Team, 2021; Low et al., 2021)- 2022
  • 2 papers: (Montgomery et al., 2022; Luke et al., 2022)- 2024
  • 3 papers: (Samoylenko et al., 2024; Choynzonov et al., 2024; Lorusso et al., 2024)- 2025
  • 1 paper: (Ramalingam et al., 2025)Figure 2: Timeline of key pembrolizumab research and approvals.

Summary

Pembrolizumab 100mg/4ml injection is effective and safe for several cancer types, with evidence supporting lower fixed doses as a cost-saving alternative to standard regimens. Clinical outcomes and safety profiles are comparable across dosing strategies, supporting flexible use based on patient needs and healthcare resources.

References

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