Effect of Currently Approved Carriers and Adjuvants on the Pre-Clinical Efficacy of a Conjugate Vaccine against Oxycodone in Mice and Rats

Abstract

Vaccination against the highly abused prescription opioid oxycodone has shown pre-clinical efficacy for blocking oxycodone effects. The current study further evaluated a candidate vaccine composed of oxycodone derivatized at the C6 position (6OXY) conjugated to the native keyhole limpet hemocyanin (nKLH) carrier protein. To provide an oxycodone vaccine formulation suitable for human studies, we studied the effect of alternative carriers and adjuvants on the generation of oxycodone-specific serum antibody and B cell responses, and the effect of immunization on oxycodone distribution and oxycodone-induced antinociception in mice and rats. 6OXY conjugated to tetanus toxoid (TT) or a GMP grade KLH dimer (dKLH) was as effective as 6OXY conjugated to the nKLH decamer in mice and rats, while the 6OXY hapten conjugated to a TT-derived peptide was not effective in preventing oxycodone-induced antinociception in mice. Immunization with 6OXY-TT s.c. absorbed on alum adjuvant provided similar protection to 6OXY-TT administered i.p. with Freund’s adjuvant in rats. The toll-like receptor 4 (TLR4) agonist monophosphoryl lipid A (MPLA) adjuvant, alone or in combination with alum, offered no advantage over alum alone for generating oxycodone-specific serum antibodies or 6OXY-specific antibody secreting B cells in mice vaccinated with 6OXY-nKLH or 6OXY-TT. The immunogenicity of oxycodone vaccines may be modulated by TLR4 signaling since responses to 6OXY-nKLH in alum were decreased in TLR4-deficient mice. These data suggest that TT, nKLH and dKLH carriers provide consistent 6OXY conjugate vaccine immunogenicity across species, strains and via different routes of administration, while adjuvant formulations may need to be tailored to individual immunogens or patient populations.

Opioid Dose- and Route-Dependent Efficacy of Oxycodone and Heroin Vaccines in Rats

“…However, OXY-KLH was effective in reducing oxycodone distribution to brain when 2.3 mg/kg oxycodone was administered subcutaneously, a dose similar to the high dose administered intravenously. OXY-KLH also reduced opioid-induced antinociception in the hot-plate assay at this same oxycodone dose given subcutaneously, as previously reported (Pravetoni et al, 2014b). The expected slower absorption of oxycodone into blood after subcutaneous compared with intravenous administration was likely responsible for the increased vaccine efficacy despite the high oxycodone dose.…”

“…However, we have previously shown that native KLH and dimer KLH are equally effective as carrier proteins for the development of oxycodone vaccines (Pravetoni et al, 2014b), and in the current study both vaccine formulations elicited similar serum opioid-specific antibody concentrations.…”

“…Experiments 1 and 2 used vaccines consisting of opioid haptens conjugated to native (didecamer) KLH (Thermo Fisher Scientific, Waltham, MA); experiment 3 used a vaccine consisting of an oxycodone hapten conjugated to KLH subunit dimer (Stellar Biotechnologies, Port Hueneme, CA) because of greater ease of formulation. We have found that native and dimer KLH conjugates of oxycodone elicit equivalent antibody responses and comparable effects on opioid distribution (Pravetoni et al, 2014b). M-KLH generates antibodies specific for heroin, 6-acetylmorphine (6-AM), morphine, and morphine-6-glucuronide, but do not appreciably cross react with methadone, buprenorphine, naloxone, naltrexone, oxycodone, or leu-enkephalin .…”

Biologics to treat substance use disorders: Current status and new directions

“…33,34 The strength of this approach is that very rare antigen-specific B and T cells are detected prior to, or shortly after immunization. [35][36][37][38][39] To date, this approach has been used to test the effect of hapten structure, 40,41 adjuvant, 42 or host genetics 42 on the B cell response to vaccines for SUD. This strategy has also been used to study the relationship between antigen-specific B and T cells and individual variability in post-immunization Ab titers, or efficacy against drug distribution and drug-induced behavior in mice.…”

“…[90][91][92] To identify the most promising carrier suitable for translation of a vaccine against oxycodone and hydrocodone, BSA, decamer and dimer KLH, TT, and a TT-derived peptide were tested. 40,42,43,[74][75][76]93 To develop vaccines for treatment of methamphetamine abuse, for which no therapies exist, immunogens containing either native or dimer KLH, or TT, showed promising pre-clinical efficacy in blocking distribution of methamphetamine to the brain and blocking a variety of methamphetamine-induced behaviors, including intravenous self-administration. [94][95][96][97][98] Other carrier proteins have adjuvant-like properties, such as the well-characterized CRM 197 .…”