Positive preclinical data from Phio Pharmaceuticals Inc., of Marlborough, Mass., propelled the company stock (NASDAQ:PHIO) dramatically upward, about 86%, at midday Friday only to see it finally settle at a more modest 36.16% increase to close May 29 at $3.05.

The data come from in vivo studies showing strong antitumoral efficacy from several company programs. The results show, the company said, that intratumoral delivery of the compounds inhibited tumor growth. The compounds were designed to silence PD-1, BRD4 and TIGIT expression. Those proteins have links to cancer patient immune cell function.

The company uses a self-delivering RNAi platform, Intasyl, designed to silence tumor-induced suppression of the immune system. The data come from pipeline programs that included PH-762, PH-894 and PH-804.

The preclinical studies showed dose-dependent attenuated tumor growth for the compounds as compared to control groups. Changes in the tumor microenvironment included an increase of tumor-infiltrating lymphocytes, including CD8+ T cells, which the company said were responsible for tumor cell killing. Changes also included an increase of activation markets on the cells.

The data were presented as an abstract at the American Society of Clinical Oncology’s scientific program, being held virtually May 29-31.

In March, Phio released preclinical findings from several animal studies with a mouse version of PH-762 (mPH-762) and with PH-894 in a validated mouse model of cancer (murine hepatocellular carcinoma model with Hepa1-6 cells). The studies show that local administration of mPH-762 or PH-894 through intratumoral injection resulted in potent antitumor effects. The treated animals showed a complete and statistically significant (p<0.0001) inhibition of tumor growth, whereas placebo-treated animals displayed exponential tumor growth, Phio said.

Money has been an ongoing concern at the company. In its March 31 form 10-Q SEC filing, Phio noted that if it failed to obtain additional funding when needed, the company would be forced to scale back or terminate its operations, seek a merger with another company or be acquired. In April, Phio closed a registered direct offering of about 1.7 million shares of common stock, at a purchase price of about $2.33 per share, for gross proceeds of about $4 million priced at-the-market under Nasdaq rules. Phio issued investors unregistered warrants to purchase up to about 1.7 million more shares. That financing should fund operations for at least another 12 months, the company noted.

Collaboration is a part of the company’s business model. Phio joined a collaboration with Helmholtz Zentrum München to design and develop targets based on Phio’s RNAi platform for T-cell and natural killer cell adoptive cell therapy for cancer. Efforts are focused on silencing tumor-induced suppression of the immune system through an sd-rxRNA platform. Phio’s lead product candidate, PH-762, is designed to elicit checkpoint blockade by inhibiting PD-1 receptor expression in T cells. Internal data, and data generated by collaborators, showed that silencing mRNA for PD-1 with PH-762 results in enhanced T-cell activation and tumor cytotoxicity.

In March, Medigene AG, of Munich/Martinsried, Germany, joined the Phio-Helmholtz Zentrum München collaboration. While financial terms of the deal weren’t disclosed, Medigene will have an option to license drugs from the collaboration.

Phio extended and expanded its research collaboration earlier in 2020 with Stockholm’s Karolinska Institute to develop self-delivering RNAi immunotherapies against targets involved in T-cell and NK cell differentiation and/or tumor-induced stress response. The goal is to produce antitumor adoptive cell therapy grafts and to enter the clinic. No financial terms were released.

Phio is the former Rxi Pharmaceuticals Group, which changed its name in November 2018.

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