Abstract 4934: CAPAC: a modular platform that can improve the safety and efficacy of existing cancer therapies

Click chemistry is a Nobel Prize winning technology that has been widely used in research across the life sciences. Shasqi’s Click Activated Protodrugs Against Cancer (CAPACTM) platform is pioneering the therapeutic application of click chemistry reactions in humans. The 1st gen CAPAC technology enables activation of potent anti-cancer agents at the tumor site while reducing systemic exposure and is comprised of a tetrazine-modified biopolymer (tumor targeting agent) injected intratumorally and a systemically administered trans-cyclooctene-modified payload, named a protodrug. Our lead clinical candidate SQ3370 (SQL70 biopolymer + SQP33, doxorubicin protodrug), is being evaluated in a Phase 2a study in solid tumors (NCT04106492). CAPAC platform is highly modular and can be applied to multiple cancer drugs especially those with narrow therapeutic index(s) due to toxicity. Because the tumor targeting agent (i.e., biopolymer) is separate from the protodrug, it enables the flexibility of interchanging different protodrugs with different mechanism of actions such as tubulin inhibitors (e.g., paclitaxel), topoisomerase inhibitors (e.g., exatecan), immune activators (e.g., TLR agonists), and others. This benefit can be translated in the clinic with tailored combinations for individual patients. Here we will present data on protodrugs of paclitaxel, exatecan, and TLR7/8a agonist. These therapeutics have shown considerable safety concerns either alone or in combination with other therapies in the clinic and may benefit from the precise activation at the tumor site that can be achieved by the CAPAC platform. In vitro cytotoxicity assays showed ≥20 fold-attenuation of both paclitaxel and exatecan protodrugs in various cancer lines. In a proliferation assay using mouse splenocytes we observed ≥100-fold attenuation of a TLR7/8a protodrug. These results suggest that the protodrugs may exhibit higher therapeutic indeces with enhanced safety profile. We tested the anti-tumor efficacy of paclitaxel protodrug in combination with SQL70 biopolymer in NCI-N87 gastric cancer xenograft tumor model. The doses of paclitaxel protodrug were 4x or 10x molar equivalent to the MTD of conventional paclitaxel. We observed significant reduction of tumor growth compared to vehicle (p<0.0001) and minimal body weight loss suggesting enhanced safety profile. In vivo studies to determine the safety and efficacy of these protodrugs are ongoing and will be presented. The data presented illustrates how the CAPAC platform is modular and expands the therapeutic window of different cancer therapies to achieve greater effect. This modularity enables the rapid access of therapeutic combinations. Moreover, as the click chemistry activation is independent of biological characteristics of tumors, CAPAC payloads are highly translatable across species and accelerate the path to the clinic.

Citation Format: George Coricor, Jesse M. McFarland, Masa Aleckovic, Sangeetha Srinivasan, John Lee, Leslie Priddy, Matthew Tso, Tri-Hung Nguyen, Jose M. Mejia Oneto. CAPAC: a modular platform that can improve the safety and efficacy of existing cancer therapies. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4934.

Abstract B43: Combining SQ3370, a doxorubicin-based therapeutic, with TLR and STING agonists enhances antitumor effects in murine tumor models

SQ3370, the lead investigational asset of the CAPACTM (Click Activated Protodrugs Against Cancer) platform, is a therapeutic based on doxorubicin which can induce immunogenic cell death in mouse tumors making it a suitable candidate for combination approaches with immunotherapies that target antigen-presenting cells. Here, we show the effects of SQ3370 combined with either TLR9 or STING agonists. Immunocompetent mice were inoculated with MC38 tumors. Once tumors reached ~100mm3, SQ3370 was administered in two parts: 1) a tetrazine-modified biopolymer was injected into the tumor and 2) a protodrug of doxorubicin modified with a trans-cyclooctene (TCO) was given intravenously as five daily doses. Efficient reaction between the biopolymer and protodrug releases the active drug in situ, delivering higher drug concentrations specifically to the tumor site compared to conventional doxorubicin, which leads to increased efficacy and reduced systemic toxicity. TLR9 and STING agonists were administered intratumorally either as monotherapies or in combination with SQ3370 by co-injection with the biopolymer. Tumor immune composition was assessed by flow cytometry and multiplex immunofluorescent analysis. Combining SQ3370 with either TLR9 or STING agonists led to a significant reduction in tumor growth and prolonged survival of MC38 tumor-bearing mice compared to any monotherapy. Higher doses of either immune adjuvant increased the effect on tumor growth inhibition, suggesting a dose-dependent effect. Complete regression of tumors was observed occasionally in mice treated with a single agent, most commonly with the TLR9 agonist. However, both combination treatments with SQ3370 increased the number of complete responses. Assessment of immune cell infiltration of tumors treated with SQ3370 suggested an increase in antitumor immune responses that were consistent with a doxorubicin-driven induction of immunogenic cell death, including an increase in tumor-infiltrating T-cells. The addition of the TLR9 agonist to SQ3370 further elevated this antitumor immune response. In line with these results, we observed regression of distal, non-injected tumors using a MC38 dual tumor model. A higher fraction of animals treated with SQ3370 + TLR9 agonist (5 out of 10) showed complete tumor regression (absence of both tumors) compared to animals receiving the SQ3370 monotherapy (1 out of 10). Tumor rechallenge of animals with complete regressions revealed a sustained response in line with T-cell mediated antitumor immunity. Previous studies have shown that SQ3370 improves safety and efficacy as compared to conventional doxorubicin. Here, we show that SQ3370 also activates an antitumor immune response and modulates several immune cell populations, particularly T-cells, to mount a lasting antitumor immune response. SQ3370 is currently being evaluated in a clinical trial in advanced solid tumors (NCT04106492) as a monotherapy. Combination strategies of SQ3370 with immunotherapies may further increase its efficacy and provide enhanced benefit to cancer patients.

Citation Format: Masa Aleckovic, Sangeetha Srinivasan, Jesse M McFarland, Leslie Priddy, Matthew Tso, Jose M Mejia Oneto. Combining SQ3370, a doxorubicin-based therapeutic, with TLR and STING agonists enhances antitumor effects in murine tumor models [abstract]. In: Proceedings of the AACR Special Conference: Tumor Immunology and Immunotherapy; 2022 Oct 21-24; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2022;10(12 Suppl):Abstract nr B43.

Abstract A029: SQ3370: CAPAC platform enables tumor-localized therapy and minimizes systemic toxicities

Conventional chemotherapies lack specificity for tumor tissue, have a low therapeutic index, and induce systemic toxicities including cardiomyopathy. SQ3370 utilizes the Click Activated Protodrugs Against Cancer (CAPAC) platform to localize doxorubicin (Dox) to tumor tissue while minimizing systemic exposure. SQ3370 consists of an intratumoral injection of a biopolymer followed by 5 daily intravenous doses of an attenuated protodrug of Dox. The tumor-localized activation of Dox is enabled by mutually reactive click chemistry groups on the biopolymer and protodrug, and is therefore agnostic to tumor characteristics that can vary from patient to patient. This allows the CAPAC platform to be readily applicable to diverse tumor types, including heterogeneous sarcoma subtypes. The lead candidate, SQ3370 is currently being evaluated in a Phase I study in patients with advanced solid tumors (NCT04106492). In preclinical studies, SQ3370 treatment showed reduced toxicity, enabling doses of 19.1-fold and 8.9-fold the maximum tolerated dose of conventional Dox in mice and dogs, respectively. Further, there was no evidence of cardiotoxicity in dogs at this dose. In syngeneic dual-tumor mouse models of MCA205 fibrosarcoma, MC38 colon carcinoma, and B16-F10 melanoma, only one tumor was injected with the biopolymer. Following 5 daily intravenous doses of the protodrug, dose-dependent antitumor responses were seen in the injected and non-injected lesions across all syngeneic models. Furthermore, T-cell infiltration was observed in both lesions of the MC38 dual-tumor model, suggesting activation of an antitumor immune response by SQ3370. The combination of SQ3370 with an immune adjuvant (TLR9 agonist) further prolonged overall survival, improved the antitumor response, and increased the number of complete responses compared to the monotherapy, likely by enhancing the immune activation effects of SQ3370. Conventional Dox can induce cardiomyopathy at incidences of 1-20% for cumulative doses from 300-500 mg/m2 in humans. In the Phase I trial, SQ3370 was well tolerated in patients receiving more than 1000 mg/m2 Dox in cumulative doses. Treated tumors included sarcoma (73%), breast cancer (7.7%), gyne (7.7%), and others (11.5%). Dose escalation is ongoing. Most frequent adverse events (AEs), included nausea, fatigue, and anemia. Ejection fraction (LVEF), indicative of cardiac function, remained normal during the study period. No AEs that led to discontinuation or death were related to SQ3370 by investigator assessment.In summary, SQ3370 facilitates localization of Dox at the tumor with minimal systemic toxicity and demonstrates the first proof of concept of the click chemistry-based CAPAC platform. The CAPAC Platform represents a new therapeutic modality to treat solid tumors by using a drug with known efficacy, such as Dox, and expanding its pharmacological capabilities.

Citation Format: Jose M. Mejia Oneto, Sangeetha Srinivasan, Jesse M. McFarland, Matthew Tso, Masa Aleckovic. SQ3370: CAPAC platform enables tumor-localized therapy and minimizes systemic toxicities [abstract]. In: Proceedings of the AACR Special Conference: Sarcomas; 2022 May 9-12; Montreal, QC, Canada. Philadelphia (PA): AACR; Clin Cancer Res 2022;28(18_Suppl):Abstract nr A029.

Abstract CT177: SQ3370 in advanced solid tumors: Interim phase 1 results

Background: SQ3370, a novel therapy, utilizes Shasqi’s proprietary Click Activated Protodrugs Against Cancer (CAPAC) platform where mutually-reactive click chemistry groups release Doxorubicin (Dox) at the tumor site while minimizing systemic exposure. In animals, SQ3370 enhanced T-cell infiltration, survival, and showed activity in both injected and non-injected lesions. Minimal to no toxicity, including no cardiotoxicity was seen in up to 9-fold dose increases in animals. Conventional Dox can induce cardiomyopathy with incidences of 6-20% for cumulative doses of 500 mg/m2 in humans. Here we report interim results of the Phase 1 trial (SQ3370-001; NCT04106492).

Methods: SQ3370 has 2 components: 1) Intratumoral injection of a protodrug-activating biopolymer (SQL70); 2) then 5 consecutive daily IV infusions of an attenuated protodrug of Dox (SQP33). Key criteria for enrollment include locally advanced to metastatic solid tumors, ≤300 mg/m2 prior exposure to DOX, ECOG status 0 or 1, and no limit to the number of prior systemic therapies. Primary objectives include safety and determining Phase 2 dose. Dose escalation was assessed in 2 stages: 1) accelerated titration; 2) 3+3 design. Dose-limiting toxicity (DLT) was evaluated in cycle 1.

Results: As of 26NOV2021 data cut, 17 patients (pts) in 8 dose escalation cohorts have been enrolled. MTD has not been reached. Median age was 59 years (26-79), 53% were females, and were ECOG 1 (59%). Prior procedures included surgery (82%) and radiation (47%). At study entry, 82% of pts had metastases with a median number of metastatic sites being 2 (1-5). Solid tumors were sarcoma (65%), and cancers of the skin, breast, and gynecologic organs were 12% for each, respectively. Sixteen of 17 (94%) pts received prior chemotherapy with 47% receiving prior Dox. Median number of prior systemic therapies was 2 (1-7). Intratumoral injection sites include soft tissue and chest wall. Of the 17 pts, 65% received >500 mg/m2, 53% (>1000), and 29% (>2000) cumulative Dox given as SQP33. Median duration of treatment was 3 cycles (1-10). No DLTs were observed. Most frequent AEs, regardless of causality, included nausea (n = 9), fatigue (n = 6) and anemia (n = 5). No signs of cardiomyopathy were seen in pts with an echo performed within 1 mo. of study start. Although >50% of pts received >1000 mg/m2, ejection fraction (LVEF) remained normal. No AEs that led to discontinuation or death were related to SQ3370. All pts were evaluable for response. At a median follow-up of 10 wks (4-30), 65% of pts had SD as best response. Median duration of SD was 80 days (37-186) with 64% sustaining SD for ≥60 days, corresponding to an overall disease control rate of 65%. The remainder of pts had PD as best response. Over 35% of pts remain on drug.

Conclusions: SQ3370 was well tolerated. No DLTs and normal LVEF were seen with pts receiving >1000 mg/m2 Dox cumulative doses. Dose escalation is ongoing. Preliminary evidence of disease control was observed in this heavily pre-treated, high cancer burden, solid tumor pt population.

Citation Format: Sant P. Chawla, Kathleen Batty, Vivek Bhadri, Nam Bui, Alexander D. Guminski, Jose M. Mejia Oneto, Sangeetha Srinivasan, James F. Strauss, Vivek Subbiah, Mia C. Weiss, Rosalind Wilson, Nathan A. Yee, Michael Zacharian, Vineet Kwatra. SQ3370 in advanced solid tumors: Interim phase 1 results [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr CT177.

Abstract CT225: Phase 1 trial of SQ3370 in solid tumors

Conventional chemotherapeutic agents are effective for a broad array of patients, but have limited dosing capabilities, lack specificity, and often result in systemic toxicity. Conversely, newer cancer immunotherapies have been successful but benefit only a subset of patients and have varying response rates across different tumors. Here we present SQ3370, a novel approach that activates doxorubicin (Dox) at the tumor site while avoiding systemic toxicities commonly associated with the therapy, and may also activate an immune response against the tumor. SQ3370 is based on a local intratumoral injection of a prodrug-capturing biomaterial (SQL70) followed by 5 daily systemic infusions of an attenuated form of Dox (SQP33). Mutually-reactive click chemistry groups in the 2 components allow the release of active Dox at the tumor site.

While conventional Dox is known to induce immune activation [1] and enhance tumor responsiveness to checkpoint inhibitors [2], its benefit is limited by achievable tumor dose, cumulative cardiotoxicity, and systemic immunosuppression. We safely administered SQ3370 in dogs at 8.95-times the veterinary clinical dose of Dox with minimal side effects. In syngeneic mouse models, SQ3370 improved overall survival and induced a robust anti-tumor response against the injected lesion compared to conventional Dox. Surprisingly, SQ3370 also induced regression of the non-injected tumor and enhanced T-cell infiltration in both injected and non-injected tumors. We hypothesize that releasing Dox at a local site with SQ3370 activates the native immune system against the tumor. Thus, SQ3370 is a new therapeutic modality to treat tumors with a drug with known efficacy, Dox, and expanding its therapeutic window. SQ3370 may potentially also benefit patients with metastatic disease.

SQ3370-001 (NCT04106492), the first-in-human Phase 1 study, is currently open in the United States and Australia to treat patients with advanced solid tumors. Eligible patients are ≥18 years old with an injectable local or metastatic lesion for which published data indicates responsiveness to anthracyclines. Patients must be relapsed/refractory following standard of care therapy and must not have received >225 mg/m2 of Dox (or equivalent anthracycline). The cycle length is 21 days with no limit on total cycles. Primary objectives include safety, tolerability, and recommended Phase 2 dose. Additional objectives include assessment of pharmacokinetics in plasma and tumor biopsies, preliminary efficacy per RECIST 1.1, and immune response as assessed by mass cytometry.

References

1.Mattarollo, S.R., et al. Pivotal Role of Innate and Adaptive Immunity in Anthracycline Chemotherapy of Established Tumors, Cancer Res 2011; 71(14):4809-4820.

2.Zitvogel L., et al. Mechanism of action of conventional and targeted anticancer therapies: reinstating immunosurveillance. Immunity. 2013;39:74-88.

Citation Format: Alexander Guminski, Ding Wang, Nam Bui, Vivek Bhadri, Madhawa De Silva, Robert Steffner, Nathan A. Yee, Sangeetha Srinivasan, Jose M. Mejia Oneto, M. Wayne Saville, Vivek Subbiah. Phase 1 trial of SQ3370 in solid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr CT225.

Abstract 1347: The CAPAC Platform maximizes therapeutic benefit and reduces systemic cytotoxic exposure in small and large animals

The Click Activated Protodrugs Against Cancer (CAPACTM) platform aims to beat cancer without poisoning the body by activating powerful cancer therapies at the tumor site(s). CAPAC's mechanism of activation is based on click chemistry and is therefore agnostic to tumor characteristics, biomarker expression or other biological factors that vary across patients. This allows the CAPAC platform to be readily applicable to diverse tumor types. We describe the safety, pharmacokinetic and therapeutic benefits of SQ3370, the lead candidate of the CAPAC Platform, in small and large animals. SQ3370 consists of 2 components, SQL70 biopolymer and SQP33 protodrug. First, SQL70, a tetrazine-modified sodium hyaluronate biopolymer, is injected at the tumor site. Then, SQP33, a trans-cyclooctene (TCO)-modified protodrug of Doxorubicin (Dox) is given by IV infusion as 5 daily doses. The SQP33 protodrug has attenuated toxicity and is converted to active Dox by the SQL70 biopolymer at the tumor site through a highly efficient covalent reaction between tetrazine and TCO moieties.

In mice, when administered in subcutaneous, intramuscular or intraperitoneal regions, around 50% of SQL70 was detectable after 2 weeks at the injection site. Biodistribution results suggested clearance of SQL70 by hepatic and renal routes. The MTD of SQ3370 in mice was nearly 20-times that of conventional Dox. Anti-tumor efficacy was evident even at 0.37x the MTD of SQ3370 suggesting that increasing the SQ3370 dosage to its MTD can maximize therapeutic benefit. Safety evaluation in 72 dogs that received either SQL70 biopolymer alone, SQP33 protodrug alone or both together (SQ3370) showed that all agents were well tolerated. The Highest Non-Severely Toxic Dose (HNSTD) of SQ3370 was 8.95 mg/kg/cycle in Dox Eq, at which dose there were minimal systemic adverse events and no evidence of cardiotoxicity. (The standard veterinary clinical dose for Dox in dogs is 1 mg/kg/cycle). The PK profiles in dogs demonstrated that SQL70 biopolymer efficiently captures the protodrug from circulation and releases active Dox.

In conclusion, the CAPAC Platform represents a new therapeutic modality to treat solid tumors by using a drug with known efficacy, such as doxorubicin, and expanding its pharmacological capabilities. The CAPAC Platform enables higher concentrations of the active drug at the tumor site and minimizes systemic adverse effects associated with conventional chemotherapy. SQ3370 is currently being evaluated in a Phase I study in patients with advanced solid tumors (https://clinicaltrials.gov/ct2/show/NCT04106492).

Citation Format: Sangeetha Srinivasan, Nathan A. Yee, Amir Mahmoodi, Michael Zakharian, M. Wayne Saville, Jose M. Mejia Oneto. The CAPAC Platform maximizes therapeutic benefit and reduces systemic cytotoxic exposure in small and large animals [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1347.

Correction: Click activated protodrugs against cancer increase the therapeutic potential of chemotherapy through local capture and activation

[This corrects the article DOI: 10.1039/D0SC06099B.].

Click activated protodrugs against cancer increase the therapeutic potential of chemotherapy through local capture and activation

A desired goal of targeted cancer treatments is to achieve high tumor specificity with minimal side effects. Despite recent advances, this remains difficult to achieve in practice as most approaches rely on biomarkers or physiological differences between malignant and healthy tissue, and thus benefit only a subset of patients in need of treatment. To address this unmet need, we introduced a Click Activated Protodrugs Against Cancer (CAPAC) platform that enables targeted activation of drugs at a specific site in the body, i.e., a tumor. In contrast to antibodies (mAbs, ADCs) and other targeted approaches, the mechanism of action is based on in vivo click chemistry, and is thus independent of tumor biomarker expression or factors such as enzymatic activity, pH, or oxygen levels. The CAPAC platform consists of a tetrazine-modified sodium hyaluronate-based biopolymer injected at a tumor site, followed by one or more doses of a trans-cyclooctene (TCO)-modified cytotoxic protodrug with attenuated activity administered systemically. The protodrug is captured locally by the biopolymer through an inverse electron-demand Diels–Alder reaction between tetrazine and TCO, followed by conversion to the active drug directly at the tumor site, thereby overcoming the systemic limitations of conventional chemotherapy or the need for specific biomarkers of traditional targeted therapies. Here, TCO-modified protodrugs of four prominent cytotoxics (doxorubicin, paclitaxel, etoposide and gemcitabine) are used, highlighting the modularity of the CAPAC platform. In vitro evaluation of cytotoxicity, solubility, stability and activation rendered the protodrug of doxorubicin, SQP33, as the most promising candidate for in vivo studies. In mice, the maximum tolerated dose (MTD) of SQP33 in combination with locally injected tetrazine-modified biopolymer (SQL70) was determined to be 19.1-times the MTD of conventional doxorubicin. Pharmacokinetics studies in rats show that a single injection of SQL70 efficiently captures multiple SQP33 protodrug doses given cumulatively at 10.8-times the MTD of conventional doxorubicin with greatly reduced systemic toxicity. Finally, combined treatment with SQL70 and SQP33 (together called SQ3370) showed antitumor activity in a syngeneic tumor model in mice.

The Click Activated Protodrugs Against Cancer (CAPAC) platform uses click chemistry to activate cytotoxic drugs directly at a target site with minimal toxicity, overcoming limitations of conventional chemotherapy and traditional targeted therapies.

Abstract LB-002: SQ3370 enhances the safety of chemotherapeutics via local activation therapy

With systemic chemotherapy, only 1-2% of the administered dose actually reaches a localized tumor, while the remaining leads to adverse off-target toxicities, including immunosuppression. Hence, there is a critical need to locally deliver cytotoxics directly to the tumor. Our patented approach (SQ3370) consists of:

(1) SQL70 - a drug-activating biomaterial carrying no payload

(2) SQP33 - a chemically-modified prodrug of doxorubicin (Dox) with attenuated activity.

SQL70 is injected at the tumor site followed by SQP33 administered systemically. The prodrug first concentrates to the biomaterial at the tumor site due to their complementary chemical reactivities. The active drug is then spontaneously released over multiple days, providing sustained local delivery directly to the tumor region while reducing systemic side effects.

Previously, we have shown that the greater safety of SQP33 allows it to be given at over 38 times the dose of standard Dox in SQL70-injected mice. Pharmacokinetic and biodistribution studies in SQ3370-treated rodents and dogs show that SQP33 disappears from plasma within the first hour of administration, likely due to the rapid concentration to SQL70. Without SQL70, SQP33 shows minimal spontaneous conversion to activated Dox. These studies also indicate that a single injection of SQL70 can activate multiple doses of SQP33, maximizing the local therapeutic index.

Recent studies demonstrate that SQ3370 treatment enhances therapeutic response and survival in tumor-bearing mice: In a syngeneic MC38 colorectal cancer model, SQ3370 slowed tumor progression in 8/10 mice, showing improved efficacy compared to standard Dox or anti-PD-1 therapy.

In mice bearing dual tumors, with one tumor site injected locally with SQL70, we observed that SQP33 can induce a response in both primary and secondary tumors, suggestive of an anti-tumor immune activation effect. Furthermore, we found that SQ3370 synergizes with anti-PD-1, expanding potential treatment options in the clinic and highlighting the advantages of immune-sparing cytotoxic therapy.

Collectively, our results demonstrate that SQ3370 enables delivery of cytotoxic drugs to a target site while limiting exposure in off-target tissues in small and large animals, leading to improvements in both safety and efficacy.

Citation Format: Nathan A. Yee, Sangeetha Srinivasan, Maksim Royzen, Jose M. Mejia Oneto. SQ3370 enhances the safety of chemotherapeutics via local activation therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr LB-002.

Bio-Orthogonal Chemistry and Reloadable Biomaterial Enable Local Activation of Antibiotic Prodrugs and Enhance Treatments against Staphylococcus aureus Infections

Systemic administration of antibiotics can cause severe side-effects such as liver and kidney toxicity, destruction of healthy gut bacteria, as well as multidrug resistance. Here, we present a bio-orthogonal chemistry-based strategy toward local prodrug concentration and activation. The strategy is based on the inverse electron-demand Diels-Alder chemistry between trans-cyclooctene and tetrazine and involves a biomaterial that can concentrate and activate multiple doses of systemic antibiotic therapy prodrugs at a local site. We demonstrate that a biomaterial, consisting of alginate hydrogel modified with tetrazine, is efficient at activating multiple doses of prodrugs of vancomycin and daptomycin in vitro as well as in vivo. These results support a drug delivery process that is independent of endogenous environmental markers. This approach is expected to improve therapeutic efficacy with decreased side-effects of antibiotics against bacterial infections. The platform has a wide scope of possible applications such as wound healing, and cancer and immunotherapy.

In Vivo Bioorthogonal Chemistry Enables Local Hydrogel and Systemic Pro-Drug To Treat Soft Tissue Sarcoma

The ability to activate drugs only at desired locations avoiding systemic immunosuppression and other dose limiting toxicities is highly desirable. Here we present a new approach, named local drug activation, that uses bioorthogonal chemistry to concentrate and activate systemic small molecules at a location of choice. This method is independent of endogenous cellular or environmental markers and only depends on the presence of a preimplanted biomaterial near a desired site (e.g., tumor). We demonstrate the clear therapeutic benefit with minimal side effects of this approach in mice over systemic therapy using a doxorubicin pro-drug against xenograft tumors of a type of soft tissue sarcoma (HT1080).