It said it is buying shares worth US$510,000 and is funding the transaction from a loan facility.
PDS said on Tuesday it plans to raise around US$45mln via the issue of new stock.
Once the fundraiser is complete, NetScientific expects its stake in the US biotech to be diluted down slightly to 4.86% from 5.7% currently. The holding is worth around £8.3mln at current prices.
PDS is a clinical-stage life sciences group whose main platform, Versamune, trains the immune system to unleash powerful targeted T-cell attacks that could “dramatically improve treatment and patient outcomes across the cancer spectrum”.
Dr Ilian Iliev, NetScientific chief executive who sits on the board of the US-listed investee firm, said: "Following a transformational year for PDS, and growing market recognition of the potential of its Versamune platform, this latest investment provides PDS with the resources to continue executing its ambitious strategy in the immuno-oncology space."