Lipid Nanoparticles – Antibody-Drug Conjugates (ADCs)

Of the hundreds of clinical trials conducted by pharmaceutical and biopharma companies, only 11 antibody-drug conjugate (ADC) products have been approved by the FDA. Despite this low number, the Ascendia Pharmaceutical Solutions team has experience in working with ADCs and a particular specialty in lipid nanoparticles (LNPs), which are growing in use as a drug delivery method due to their biocompatibility, stability, and payload options.

ADC drugs, developed primarily in oncology, fall into three different classes – DNA damaging agents, microtubule inhibitors, or topoisomerase I inhibitors – based on their mechanism of actions. Figure 1 outlines the classes.¹

As outlined in figure 1, the approved ADCs are classified by mechanism of action, payload, and indication based on decreasing potency. For further explanation, Zynlonta™ has the highest potency (picomolar range) and Trodelvy™ has the lowest potency (nanomolar range). These drugs or payloads with the highest potency are DNA damaging agent PBD (IC₅₀ in picomolar range to lowest potency topoisomerase I inhibitor SN-38 with an IC₅₀ values in nanomolar range.²)

These molecules, highly cytotoxic in nature, work by three mechanisms:

• DNA damaging
• Microtubule inhibition
• Topoisomerase inhibition.

Drug payloads can dictate ADC efficacy and toxicity. The net positive versus negative charge and hydrophobicity versus hydrophilicity of payload may also influence the clearance rate, which may lead to altering the on-target efficacy and off-target toxicity of an ADC. In addition, the metabolism of ADC may have an impact on safety and efficacy. SN-38, a lactone-based molecule, for example, is inactivated in the liver, and can lead to inherent toxicity by the opening of a lactone ring.³

Growing Acceptance of Lipid Nanoparticles 

LNP-antibodies conjugates have gained acceptance for selective and efficient delivery of cancer drugs.⁴ As shown in Figure 1, LNP carriers require surface functionalization with their carboxyl groups to tether antibodies via known chemical reactions requiring 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydroxy succinimide (NHS) couplings with primary amines of antibodies. Antibodies with Fc region can conjugate via thiolation reaction at site-specific free sulfhydryl groups by click chemistry with maleimide amino groups of the LNPs.

Functionalization through covalent conjugation of an antibody results in stable bond formation and allows controls of ligand density. Considering the hydrodynamic radius of an antibody (20 nm), the size of chemically functionalized/conjugated LNPs is expected to increase by 40 nm. The smaller size of the antibody clearly allows for deeper penetration into tumor cells.

LNPs can be activated by two different methods. One way is to engineer it together with lipid and targeting ligands. The second approach is to target ligand for post insertion into LNPs. The latter is preferred since the ligands are better exposed at the outer surface LNPs, as opposed to encapsulating a ligand within the LNPs, which allows a lesser degree of exposure to the outer surface.

LNPs with long circulating entities like DSPE-PEG bearing different functional groups such as amino (DSPE-PEG-NH₂), carboxyl (DSPE-PEG-COOH), maleimide (DSPE-PEG-maleimide) or NHS (e.g. DSPE-PEG-NHS), allow the anchoring of an antibody via klick chemistry to a covalent linkage.

Table 1 (below) shows the formation of covalent linkages via a specific ligand with lipids and antibodies used against different tumors.

LNP Expertise from Pre-formulation to Manufacturing

Ascendia Pharmaceutical Solution’s LNP capabilities extend from pre-formulation through manufacturing, to first-in-human trials. Our proprietary LipidSol^® lipid-based technology can be engineered to fit with ADCs for targeted delivery of potent drugs to tumor cells.⁹ LipidSol enables the encapsulation of drugs in LNPs by utilization of fatty acids and polar headgroup entities commercially available and listed in the FDA inactive ingredient database (FDA IID) or accessible to a novel lipid library.

We are also a leader in scalable LNP production as drug development scales up, making us a one-stop shop for LNP formulation and manufacturing. As a specialty CDMO, we can advance a drug through the entire development process.

We can perform nanoparticle formulations via bead-milling, microfluidization, and homogenization for solid dosage forms or suspended for injection. Ascendia Pharmaceutical Solutions also has the ability to formulate self-emulsifying lipid systems, dispersed amorphous systems, and nano-emulsions to create other dosage forms, including oral, topical, inhalation, or ocular.

In our state-of-the-art cGMP manufacturing suites, our experienced scientists work with the most advanced and current manufacturing equipment to help drug development projects stay on schedule and within budget. Ascendia Pharmaceutical Solutions employs Precision Nanosystems and NETZSCH Group Vakumix equipment to ensure early-stage manufacturing is efficient.

Contact us today and learn how the Ascendia Difference can improve your ADC projects.

References

1. S. Ali and J. Huang, Drug Development & Delivery, 2024 (June)
2. D. M. Goldenberg and R. M. Sharkey, Antibody-drug conjugates targeting TROP-2 and incorporating SN-38: a case study of anti-TROP-2 sacituzumab govitecan. MAbs. 2019, 11, 987–95. 

3. R. H. Mathijssen, R. J. van Alphen, J. Verweij, W. J. Loos, K. Nooter, G. Stoter, and A. Sparreboom, Clinical pharmacokinetics and metabolism of irinotecan (CPT-11). Clin Cancer Res. 2001, 7, 2182–2194. 

4. A. C. Marques, P. C. Costa, S. Velho and M. H. Amaral, Lipid nanoparticles functionalized with antibodies for anticancer drug therapy, Pharmaceutics 2023, 15, 216. 

5. Jain, S.; Deore, S.V.; Ghadi, R.; Chaudhari, D.; Kuche, K.; Katiyar, S.S. Tumor microenvironment responsive VEGF-antibody functionalized pH sensitive liposomes of docetaxel for augmented breast cancer therapy. Mater. Sci. Eng. C 2021, 121, 1118. 

6. Lu, X.; Liu, S.; Han, M.; Yang, X.; Sun, K.; Wang, H.; Mu, H.; Du, Y.; Wang, A.; Ni, L.; et al. Afatinib-loaded immunoliposomes functionalized with cetuximab: A novel strategy targeting the epidermal growth factor receptor for treatment of non-small-cell lung cancer. Int. J. Pharm. 2019, 560, 126–135. 

7. Merino, M.; Lozano, T.; Casares, N.; Lana, H.; Troconiz, I.F.; ten Hagen, T.L.M.; Kochan, G.; Berraondo, P.; Zalba, S.; Garrido, M.J. Dual activity of PD-L1 targeted Doxorubicin immunoliposomes promoted an enhanced efficacy of the antitumor immune response in melanoma murine model. J. Nanobiotechnol. 2021, 19, 102