The boards of biotech firms Inspyr Therapeutics and Lewis and Clark Pharmaceuticals have approved a merger deal through which Inspyr will acquire Lewis and Clark in an all-stock transaction. No financial details have been disclosed, but the firms say that on completion Lewis and Clark will become a wholly owned subsidiary of Inspyr, with Lewis and Clark shareholders owning 50% of Inspyr’s common stock.

The combined entity will develop Inspyr’s mid-clinical-stage anticancer prodrug therapeutic mipsagargin, continue to develop Lewis and Clark’s preclinical-stage adenosine receptor modulator candidates, and leverage the firm's proprietary platform to expand its pipeline.  

“Our capabilities will span from the discovery of new molecules through clinical development and regulatory filings,” said Peter Grebow, Ph.D., chairman of Inspyr. “Over the last 12 months, we embarked on a path to unlock the potential of our lead therapy mipsagargin, strengthen the management team, and broaden the pipeline. We will now have proprietary platform technology, additional expertise and laboratory facilities, while also broadening the pipeline.

Mipsagargin targets the prostate-specific membrane antigen (PSMA) expressed on prostate cancer cells and on tumor-associated blood vessels in other tumor types. The prodrug comprises the cytotoxic thapsigargin derivative 12ADT coupled to a peptide cap that is only removed in the tumor environment to release the active agent. Mipsagargin has undergone a Phase II study in patients with Nexavar® (sorafenib)-refractory hepatocellular carcinoma (HCC) and has been granted FDA orphan drug designation for the HCC indication. The drug is also undergoing preclinical development as combination therapy with Nexavar against PSMA-expressing liver cancer.

In February, the firm said it would start a preclinical program to evaluate mipsagargin as a combination therapy with paclitaxel and subsequently in combination with DC101, a Cyramza®(ramucirumab) surrogate antibody, against PSMA-expressing gastric cancers. An additional aim is to exploit Lewis and Clark’s wet laboratory expertise to develop new PSMA-targeting prodrugs that carry different anticancer payloads.

In March, Inspyr secured a $100 million financing agreement with Milost Global, through which the private equity firm will invest up to $25 million in Inspyr common stock and up to $75 million in convertible notes.

Lewis and Clark is focused on the development of A2A and A2B antagonist, and A2A agonist candidates for multiple therapeutic indications. The firm is developing four preclinical-stage programs, including a dual A2A/A2B antagonist as a potential treatment for solid and hematologic cancers; A2A agonists with potential utility against inflammatory and autoimmune diseases, including arthritis, Crohn’s disease, diabetic nephropathy, and psoriasis; and an A2B antagonist with potential applications in the treatment of asthma, type 2 diabetes, atherosclerosis, and nonalcoholic fatty liver disease.

Inspyr said it will continue preclinical development of the Lewis and Clark pipeline to aid candidate selection and projects initiating IND-enabling studies with lead adenosine receptor modulators during the second half of 2018.

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