Abstract P2-13-09: An investigational next generation ADC (DAN-311) is highly effective in HER2-low breast cancer models

Background: Nanoparticles (NPs) have been developed to enhance the pharmacokinetic (PK) and biodistribution characteristics of molecules. Many early NPs, including liposomes, dendrimers, and polymeric micelles, were limited in their ability to access target tissue and lacked uniform release rates. A promising nanoparticle therapeutic has been developed utilizing biocompatible polymer chemistry. By covalently attaching chemotherapy to the polymer through linker strategies that allow for modulation of release and PK, polymeric nanoparticles provide advantages over encapsulation nanoparticle strategies. Additionally, a targeting moiety can be added to make a next-generation ADC with the drug-to-antibody-ratio (DAR) well controlled and significantly greater (e.g. DAR=60) compared to traditional ADCs. DAN-311 is a Next-Generation Antibody Drug Conjugate (NG-ADC) with a HER2-targeting agent (trastuzumab) conjugated to a therapeutic nanoparticle with camptothecin (CPT), a topoisomerase I inhibitor. The advantages that DAN-311 offers to the 50% of patients with breast cancer have tumors with low HER2 expression is two-fold: 1) the larger DAR can lead to an enhanced bystander effect where the chemotherapy is effective against the targeted cells and also the neighboring cells, and 2) the nanoparticle is also active against HER2 non-expressing cells through the enhanced permeability and retention (EPR) effect. Here, we present the control and consistency of key DAN-311 NP characteristics that allow for efficient and large scale-manufacture, including particle size, chemotherapy load (DAR), and payload release rate. We also report the enhanced efficacy of DAN-311 in a HER2-low breast cancer (JIMT-1) xenograft mouse model. Methods: Release of CPT from nanoparticles across range of combined properties was evaluated by HPLC in pH 5.5 PBS (endosomal pH), pH 7.4 PBS (physiologic pH), mouse plasma, and human plasma. HER2-low breast cancer tumor cells (JIMT-1) were implanted into female CB.17 SCID mice. Mice were randomized to vehicle or treatment arms until tumors reached 2000 mm3 or day 46. The groups evaluated included trastuzumab, the non-targeted core nanoparticle of DAN-311, and DAN-311. Results: NPs across a wide range in polymer molecular weight and drug loading demonstrate striking consistency in particle size (ca. 30-45 nm), DAR (ca. 60-70 CPT molecules), and demonstrate linear release kinetics in various physiologically-relevant media. DAN-311 exhibited significantly greater tumor growth inhibition compared to vehicle, core particle, and trastuzumab. The non-targeted core particle also demonstrated significant tumor growth inhibition compared to vehicle and trastuzumab, which was sustained for at least 3 weeks after the final dose.

Core particle = same DAN-311 nanoparticle without HER2 targeting. Conclusions: DAN-311, a Next-Generation ADC with a HER2-targeting agent (trastuzumab) on a polymeric nanoparticle conjugated with CPT demonstrated a significant ability to inhibit tumor growth in a HER2-low xenograft mouse model. Importantly, the nanoparticle targeted delivery of CPT for cells with low expression of receptors is highly efficient in cell killing and the large DAR provides greater bystander cell killing capability; and non-HER2-expressing lesions or regions of tumors will additionally be treated by the nanoparticle through EPR. DAN-311 is advancing to clinical study to treat HER2-low metastatic breast cancer patients.

TreatmentDose (mg/kg)Day 22 TGI (%)Day 46 TGI (%)Trastuzumab10 mg/kg Tras629Core particle1 mg/kg CPT3955DAN-31110 mg/kg Tras/1 mg/kg CPT8777

Citation Format: Ashley P Wright, Emily A Wyatt, Robert J Lamm, Carl M Blumenfeld, Jodi D Bradley, Gayatri Shrikhande, Timothy Hagerty. An investigational next generation ADC (DAN-311) is highly effective in HER2-low breast cancer models [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P2-13-09.

Abstract P5-16-16: A novel investigational nanoparticle therapeutic (DAN-222) for breast cancer and other solid tumors

Background: Here we introduce a novel nanoparticle therapeutic, DAN-222, which offers a variety of potential clinical benefits in delivery of chemotherapy versus native drug, including a broader therapeutic index. DAN-222 is a polymeric nanoparticle covalently conjugated with camptothecin (CPT), a topoisomerase I inhibitor, that demonstrates enhanced efficacy over native CPT at the same dose and has significantly reduced bone marrow exposure (limiting potential safety concerns), thus widening the therapeutic index with respect to both efficacy and safety. The nanoparticle therapeutic provides sustained drug exposure through conjugation of the chemotherapy payload to the novel biocompatible polymer scaffold that can be modulated by choice of linker, allowing for optimization of the release rate for a given payload and target. To illustrate the flexibility and capabilities of modulating payload release kinetics, we present a series of CPT-containing nanoparticles with different linkers encompassing a wide range of in vitro release rates. We also demonstrate the vastly enhanced efficacy of DAN-222 in multiple breast cancer xenograft mouse models. Methods: In vitro release: Release of CPT from nanoparticles formed with various linkers was evaluated by HPLC in pH 5.5 PBS (endosomal pH), pH 7.4 PBS (physiologic pH), mouse plasma, and human plasma. Efficacy: Breast cancer xenograft tumor models with human BT-474 and MDA-MB-231 were propagated in CB.17 SCID and NCr nu/nu mice respectively, with 10 animals per group. Results: All linkers demonstrate linear kinetics and release slowly at reduced pH, consistent with the mechanism of release. At physiologic pH, a diversity of in vitro release rates is achieved by modulating the sensitivity of the linker. Importantly, all linkers have similar release in mouse and human plasma, indicating strong cross-species translation.

Results in the mouse xenograft models showed that DAN-222 had a superior and sustained efficacy compared to CPT and irinotecan (an approved topoisomerase-1 inhibitor) as demonstrated by tumor growth inhibition.

Conclusions: We demonstrate the ability to modulate the payload release kinetics from the nanoparticle therapeutic by the choice of linker, with species-independent release rates. With an optimal linker selected, DAN-222 shows enhanced and sustained efficacy over native CPT. Since DAN-222 has previously been shown to have reduced bone marrow exposure of chemotherapy, it may provide a significant therapeutic advancement with a wider therapeutic index based on both enhanced efficacy and improved safety. DAN-222 is advancing to a clinical trial in HER2-negative metastatic breast cancer.

In vitro release half-lives (t1/2) (hours)Linker 1Linker 2Linker 3Linker 4Linker 5PBS, pH 5.5>50>50>50>50>50PBS, pH 7.47.120.5>50>50>50Mouse Plasma1.74.817.237.7>50Human Plasma1.64.817.137.8>50

TreatmentBT-474MDA-MB-231Day 25 TGI(%)Day 36 TGI*(%)Day 25 TGI (%)Day 32 TGI* (%)Camptothecin (3 mg/kg)64404756Irinotecan (100 mg/kg)71594751DAN-222 (3 mg/kg CPT)93967475*Day the vehicle control group reached the study endpoint.

Citation Format: Emily A Wyatt, Ashley P Wright, Carl M Blumenfeld, Robert J Lamm, Timothy Hagerty. A novel investigational nanoparticle therapeutic (DAN-222) for breast cancer and other solid tumors [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P5-16-16.

Cellular uptake and cytotoxicity of a near-IR fluorescent corrole-TiO2 nanoconjugate

We are investigating the biological and biomedical imaging roles and impacts of fluorescent metallocorrole-TiO2 nanoconjugates as potential near-infrared optical contrast agents in vitro in cancer and normal cell lines. The TiO2 nanoconjugate labeled with the small molecule 2,17-bis(chlorosulfonyl)-5,10,15-tris(pentafluorophenyl)corrolato aluminum(III) (1-Al-TiO2) was prepared. The nanoparticle 1-Al-TiO2 was characterized by transmission electron microscopy (TEM) and integrating-sphere electronic absorption spectroscopy. TEM images of three different samples of TiO2 nanoparticles (bare, H2O2 etched, and 1-Al functionalized) showed similarity in shapes and sizes with an average diameter of 29nm for 1-Al-TiO2. Loading of 1-Al on the TiO2 surfaces was determined to be ca. 20-40mg 1-Al/g TiO2. Confocal fluorescence microscopy (CFM) studies of luciferase-transfected primary human glioblastoma U87-Luc cells treated with the nanoconjugate 1-Al-TiO2 as the contrast agent in various concentrations were performed. The CFM images revealed that 1-Al-TiO2 was found inside the cancer cells even at low doses (0.02-2μg/mL) and localized in the cytosol. Bioluminescence studies of the U87-Luc cells exposed to various amounts of 1-Al-TiO2 showed minimal cytotoxic effects even at higher doses (2-2000μg/mL) after 24h. A similar observation was made using primary mouse hepatocytes (PMH) treated with 1-Al-TiO2 at low doses (0.0003-3μg/mL). Longer incubation times (after 48 and 72h for U87-Luc) and higher doses (>20μg/mL 1-Al-TiO2 for U87-Luc and >3μg/mL 1-Al-TiO2 for PMH) showed decreased cell viability.

Decorating metal oxide surfaces with fluorescent chlorosulfonated corroles

We have prepared 2,17-bis(chlorosulfonyl)-5,10,15-tris(pentafluorophenyl)corrole (1), 2,17-bis(chlorosulfonyl)-5,10,15-tris(pentafluorophenyl)corrolatoaluminum(III) (1-Al), and 2,17-bis(chlorosulfonyl)-5,10,15-tris(pentafluorophenyl)corrolatogallium(III) (1-Ga). The metal complexes 1-Al and 1-Ga were isolated and characterized by electronic absorption and NMR spectroscopies, as well as by mass spectrometry. Relative emission quantum yields for 1, 1-Al, and 1-Ga, determined in toluene, are 0.094, 0.127, and 0.099, respectively. Reactions between 1, 1-Al, and 1-Ga and TiO2 nanoparticles (NPs) result in corrole-TiO2 NP conjugates. The functionalized NP surfaces were investigated by solid-state Fourier transform infrared and X-ray photoelectron spectroscopies and by confocal fluorescence imaging. The fluorescence images for 1-Al-TiO2 and 1-Ga-TiO2 suggest a promising application of these NP conjugates as contrast agents for noninvasive optical imaging.

Individual normal laboratory values. Preliminary observations

A brief and preliminary outline is given describing a consecutive and continuing study of laboratory blood values of only 12 of 48 "normal healthy" subjects with only a few values given. The major emphasis is that of obtaining blood from each subject over a 12-week period to be repeated annually in order to determine individual values and in obtaining a chemical identification of each subject with the anticipation that more information will be available concerning the meaning and limiting parameters of "normal" biologic values. Such a study is made available through the application of modern advances in automation and the wide use of computers. It seems likely that some disorders can be discovered before clinically apparent, with the hope that consequent preventive measures and therapy may be more effective. The few values presented represent only a small part of those yet to be obtained. Much more work is needed in this study of normal values whose parameters must be further defined.

Phenylketonuria-the guthrie screening test-a method of quantitation, observations on reliability and suggestions for improvement

The Guthrie bacterial inhibition assay method of screening neonatal infants for phenylketonuria (pku) initiated mass screening for inborn errors of metabolism. It is a simple, cheap procedure admirably suited to private local use as against private or public central use. However, using parallel fluorometric determinations as a basis for comparison, and 4 mg per 100 ml serum phenylalanine as a presumptive positive threshhold, the Guthrie test yielded 53 per cent "false negatives." Extrapolating from a combination of our data and reported phenylalanine levels at three days of age or less in proved pku patients, it is estimated the Guthrie test might fail to detect one of 25 pku patients screened at three days of age or less. Means to diminish this risk are considered.