Pain is the most significant impairment and debilitating challenge for patients with bone metastasis. Therefore, the primary objective of current therapy is to mitigate and prevent the persistence of pain. Thus, cancer-induced bone pain is described as a multifaceted form of discomfort encompassing both inflammatory and neuropathic elements. We have developed a novel non-addictive pain therapeutic, PNA6, that is a derivative of the peptide Angiotensin-(1-7) and binds the Mas receptor to decrease inflammation-related cancer pain. In the present study, we provide evidence that PNA6 attenuates inflammatory, chemotherapy-induced peripheral neuropathy (CIPN) and cancer pain confined to the long bones, exhibiting longer-lasting efficacious therapeutic effects. PNA6, Asp-Arg-Val-Tyr-Ile-His-Ser-(O-β-Lact)-amide, was successfully synthesized using solid phase peptide synthesis (SPPS). PNA6 significantly reversed inflammatory pain induced by 2% carrageenan in mice. A second murine model of platinum drug-induced painful peripheral neuropathy was established using oxaliplatin. Mice in the oxaliplatin-vehicle treatment groups demonstrated significant mechanical allodynia compared to the oxaliplatin-PNA6 treatment group mice. In a third study modeling a complex pain state, E0771 breast adenocarcinoma cells were implanted into the femur of female C57BL/6J wild-type mice to induce cancer-induced bone pain (CIBP). Both acute and chronic dosing of PNA6 significantly reduced the spontaneous pain behaviors associated with CIBP. These data suggest that PNA6 is a viable lead candidate for treating chronic inflammatory and complex neuropathic pain.

The renin-angiotensin system (RAS) plays a role in cardiovascular homeostasis and hydro-electrolyte balance influencing organ function throughout the body. The classical view of RAS focused on a single biologically active metabolite, the octapeptide angiotensin (Ang)ll, created by the Angiotensin-converting enzyme (ACE). The past two decades have revealed new functions for intermediate products of the RAS beyond their role as substrates. Angiotensin 1-7 (Ang-(1—7), a RAS peptide product with actions at the Mas receptor, reportedly prevents cardiovascular disease-induced cognitive decline and cancer-induced bone pain (CIBP). However, Ang-(1—7) has a short half-life in vivo; here, we hypothesized that activating the MasR1 with a lactoside Ang-(1—7) analogue- PNA6-would attenuate inflammatory, cancer pain confined to the long bones, and chemotherapy-induced peripheral neuropathy (CIPN) for a longer-lasting efficacious therapeutic effect. PNA6, Asp-Arg-Val-Tyr-Ile-His-Ser-(O-β-Lact)-amide, was successfully synthesized on solid phase peptide synthesis (SPPS). PNA6 significantly reversed inflammatory pain induced by 2% carrageenan in mice. In a second study modeling a complex pain state, E0771 breast adenocarcinoma cells were implanted into the femur of female C57BLK/6J wild-type mice to induce cancer-induced bone pain (CIBP). Both acute and chronic dosing of PNA6 significantly reduced the spontaneous pain behaviors associated with CIBP. A third murine model of platinum drug-induced painful peripheral neuropathy was established using oxaliplatin. Mice in the oxaliplatin-vehicle treatment groups demonstrated significant mechanical allodynia compared to oxaliplatin- PNA6 treatment group mice. These data suggest that PNA6 is a viable lead candidate for treating chronic inflammatory and complex neuropathic pain.