PEP Topic 

PG2 is an investigational drug extracted from Astragalus membranaceus, which appear to have an effect on the hematopoiesis system. PG2 was studied in patients with cancer for its effect on fatigue.

Effectiveness Not Established

Research Evidence Summaries

Chen, H. W., Lin, I. H., Chen, Y. J., Chang, K. H., Wu, M. H., Su, W. H., . . . Lai, Y. L. (2012). A novel infusible botanically-derived drug, PG2, for cancer-related fatigue: a phase II double-blind, randomized placebo-controlled study. Clinical and Investigative Medicine, 35, E1–E11.


Study Purpose:

To examine the effects of PG2 on fatigue in patients with advanced cancer.

Intervention Characteristics/Basic Study Process:

PG2 was extracted from Astragalus membranaceus and is a polysaccharide mixture. It was reconstituted and dissolved in normal saline and mixed into 490 mL of normal saline for infusion. Patients were randomly assigned to the PG2 group or the placebo control group, which received infusions of 500 mL of normal saline. Patients received infusions three times a week for four weeks. After four weeks, all patients received open-label treatment with PG2 for another four weeks. Assessment of the outcomes was conducted at baseline and at the end of the first, second, and fourth week of each study cycle. A fatigue response rate was calculated as the percentage of patients who had at least a 10% improvement in fatigue scores at weeks 4 and 8.

Sample Characteristics:

  • A total of 58 patients completed the full study; there were 84 patients for safety evaluation.
  • Mean age was 60.5 years.
  • About 39% of patients were men and 61.5% were women.
  • Various tumor types were included, but  breast and head and neck cancers were the most common. Of the patients, 68% had metastatic disease.
  • Average baseline Brief Fatigue Inventory (BFI) score was 6.04. 


The study was conducted at multiple settings in Taiwan.

Phase of Care and Clinical Applications:

Patients were undergoing the end of life and palliative phases of care.

Study Design:

This was a randomized, double-blind, placebo-controlled trial with an open-label extension.

Measurement Instruments/Methods:

  • BFI, Taiwanese version
  • Hematology blood tests


About 72% of the entered patients completed four weeks of the study, and 64.4% completed eight weeks. During the first week, PG2 administration resulted in a significantly greater fatigue response rate (PG2 = 57.14%; placebo = 32.3%; p = 0.043). By weeks 2 to 4, no significant differences were observed between the groups. About 82% of those who responded to PG2 reported a sustained benefit after the subsequent open-label use. For those who initially received placebo, after four weeks of open-label use, the fatigue response rate increased significantly after PG2 administration (57.14% response rate). Adverse events associated with PG2 were rashes (n = 3), eczema (n = 2), and pruritis (n = 2); none of these required medical treatment for resolution. White blood counts and differentials were similar between the groups.


PG2 had a positive effect on fatigue in patients with advanced cancer.


  • The study had a small sample size, with less than 100 patients.
  • Measurements/methods were not well described.
  • Patient withdrawals were 10% or greater.
  • The method of evaluating adverse events was not well described; the authors just stated that assessments were performed at each visit. 
  • The study had a substantial drop-out rate. A few of these were from death with advanced disease; however, 4.4 % withdrew consent and 8.9% had protocol violations in the first cycle.

Nursing Implications:

PG2 appeared to have potential benefit in reducing fatigue among patients with advanced cancer and may provide effective palliation of this symptom. Additional research is warranted to further evaluate efficacy and adverse events.