Phase 1/2 Trial Results of a Large Surface Area Microparticle Docetaxel for the Treatment of High-Risk Nonmuscle-Invasive Bladder Cancer.

PURPOSE: We investigated the safety, preliminary efficacy, and immune effects of large surface area microparticle docetaxel (LSAM-DTX) administered by direct injection after transurethral resection of bladder tumor (TURBT), and by intravesical instillation in high-risk nonmuscle-invasive bladder cancer. MATERIALS AND METHODS: The trial followed an open-label 3+3 dose escalation with additional enrollment at the high dose. After TURBT, subjects received direct injection LSAM-DTX into the resection site and intravesical LSAM-DTX, followed by 6-week induction and 3-week maintenance intravesical LSAM-DTX courses. Tumor recurrence was evaluated by cytology, cystoscopy, or biopsy. Pharmacokinetic analysis of blood and multiplex immunofluorescence of tumor microenvironment occurred pre- and post-LSAM-DTX. RESULTS: Nineteen subjects were enrolled, 14 with prior bacillus Calmette-Guérin exposure and 16 with ≥1 prior TURBT. Direct injection and intravesical LSAM-DTX were well tolerated. In the 3 lowest dose escalation cohorts the median recurrence-free survival was 5.4 months (10 patients, median followup 8.6 months). In the high-dose and expansion cohorts median recurrence-free survival was significantly increased (p <0.05, hazard ratio 0.29) to 12.2 months (9 patients, median followup 12.4 months). Systemic docetaxel exposure was negligible and increases in antitumor immune cells were found in the tumor microenvironment along with elevations in the PD-1, PD-L1 and CTLA-4 immune checkpoint inhibitor targets. CONCLUSIONS: Post-TURBT direct injection and intravesical LSAM-DTX were well tolerated and demonstrated clinical response for patients with high-risk nonmuscle-invasive bladder cancer. Favorable immune cell infiltration and checkpoint receptor increases following LSAM-DTX treatment warrants investigation alone as well as in combination with immune checkpoint inhibitor therapy.

Response of Locally Advanced Pancreatic Cancer to Intratumoral Injection of Large Surface Area Microparticle Paclitaxel: Initial Report of Safety and Clinical Outcome.

OBJECTIVES: Large surface area microparticle paclitaxel (LSAM-PTX) provides an intratumoral (IT) chemotherapeutic depot. Safety, tolerability, and tumor response to IT LSAM-PTX delivered by endoscopic ultrasound-fine needle injection were evaluated in subjects with unresectable locally advanced pancreatic cancer (LAPC). METHODS: Ten subjects treated in a dose escalation phase and 22 additional subjects receiving 2 injections, 4 weeks apart, of 15 mg/mL LSAM-PTX were followed for 12 months. Paclitaxel pharmacokinetics were evaluated, imaging at 3 and 6 months determined tumor response, and multiplex immunofluorescence was conducted to characterize local immune response. RESULTS: Most treatment-emergent adverse events were attributed to LAPC. Plasma paclitaxel levels were negligible. Eight subjects' tumors became resectable after IT LSAM-PTX, and 5 of 6 (83%) were resected with R0. Multiplex immunofluorescence of resected tumors demonstrated increased T cells, natural killer cells, and macrophages and decreased myeloid-derived suppressor cells. Six-month disease control rate was 94%, and median overall survival was 19.7 months in the 2-injection subjects. For nonresected and resected groups, overall survival times were 18.9 and 35.2 months, respectively. CONCLUSIONS: Neoadjuvant IT LSAM-PTX, in combination with SOC, was well tolerated and may provide benefits to LAPC patients, evidenced by enhanced immune response, improved disease control rate, restaging leading to surgery, and extended survival.

Early phase trial of intracystic injection of large surface area microparticle paclitaxel for treatment of mucinous pancreatic cysts.

Background and study aims Mucinous pancreatic cystic lesions (PCLs) have the potential for malignant transformation, for which the only accepted curative modality is surgery. A novel intracystic therapy with large surface area microparticle paclitaxel (LSAM-PTX) may treat PCLs without local or systemic toxicities. Safety and preliminary efficacy of LSAM-PTX for the treatment of PCLs administered by endoscopic ultrasound-guided fine-needle injection (EUS-FNI) was evaluated. Patients and methods Ten subjects with confirmed PCLs (size > 1.5 cm) received intracystic LSAM-PTX via EUS-FNI at volumes equal to those aspirated from the cyst in sequential cohorts at 6, 10, and 15 mg/mL in a standard "3 + 3" dose-escalation protocol. The highest dose with acceptable safety and tolerability was taken into the confirmatory phase where nine additional subjects received two injections of LSAM-PTX 12 weeks apart. Subjects were followed for 6 months after initial LSAM-PTX treatment for endpoints including: adverse events (AEs), tolerability, pharmacokinetic analysis of systemic paclitaxel drug levels, and change in cyst volume. Results Nineteen subjects completed the study. No dose-limiting toxicities, treatment-related serious AEs, or clinically significant laboratory changes were reported. Systemic paclitaxel concentrations did not exceed 3.5 ng/mL at any timepoint measured and fell below 1 ng/mL by Week 2, supporting the lack of systemic toxicity. By Week 24 a cyst volume reduction (10-78 %) was seen in 70.6 % of subjects. Conclusions Intracystic injection of LSAM-PTX into mucinous PCLs resulted in no significant AEs, a lack of systemic absorption, and resulted in reduction of cyst volume over a 6 month period.

Local administration of submicron particle paclitaxel to solid carcinomas induces direct cytotoxicity and immune-mediated tumoricidal effects without local or systemic toxicity: preclinical and clinical studies.

This report describes local administration of submicron particle paclitaxel (SPP) (NanoPac®: ~ 800-nm-sized particles with high relative surface area with each particle containing ~ 2 billion molecules of paclitaxel) in preclinical models and clinical trials evaluating treatment of carcinomas. Paclitaxel is active in the treatment of epithelial solid tumors including ovarian, peritoneal, pancreatic, breast, esophageal, prostate, and non-small cell lung cancer. SPP has been delivered directly to solid tumors, where the particles are retained and continuously release the drug, exposing primary tumors to high, therapeutic levels of paclitaxel for several weeks. As a result, tumor cell death shifts from primarily apoptosis to both apoptosis and necroptosis. Direct local tumoricidal effects of paclitaxel, as well as stimulation of innate and adaptive immune responses, contribute to antineoplastic effects. Local administration of SPP may facilitate tumor response to systemically administered chemotherapy, targeted therapy, or immunotherapy without contributing to systemic toxicity. Results of preclinical and clinical investigations described here suggest that local administration of SPP achieves clinical benefit with negligible toxicity and may complement standard treatments for metastatic disease.

Inhaled Submicron Particle Paclitaxel (NanoPac) Induces Tumor Regression and Immune Cell Infiltration in an Orthotopic Athymic Nude Rat Model of Non-Small Cell Lung Cancer.

Background: This study evaluated the antineoplastic and immunostimulatory effects of inhaled (IH) submicron particle paclitaxel (NanoPac®) in an orthotopic non-small cell lung cancer rodent model. Methods: Male nude rats were whole body irradiated, intratracheally instilled with Calu-3 cancer cells and divided into six treatment arms (n = 20 each): no treatment (Group 1); intravenous nab-paclitaxel at 5.0 mg/kg once weekly for 3 weeks (Group 2); IH NanoPac at 0.5 or 1.0 mg/kg, once weekly for 4 weeks (Groups 3 and 4), or twice weekly for 4 weeks (Groups 5 and 6). Upon necropsy, left lungs were paraffin embedded, serially sectioned, and stained for histopathological examination. A subset was evaluated by immunohistochemistry (IHC), anti-pan cytokeratin staining AE1/AE3+ tumor cells and CD11b+ staining dendritic cells, natural killer lymphocytes, and macrophage immune cells (n = 2, Group 1; n = 3 each for Groups 2-6). BCL-6 staining identified B lymphocytes (n = 1 in Groups 1, 2, and 6). Results: All animals survived to scheduled necropsy, exhibited no adverse clinical observations due to treatment, and gained weight at the same rate throughout the study. Histopathological evaluation of Group 1 lung samples was consistent with unabated tumor growth. Group 2 exhibited regression in 10% of animals (n = 2/20). IH NanoPac-treated groups exhibited significantly higher tumor regression incidence per group (n = 11-13/20; p < 0.05, χ2). IHC subset analysis revealed tumor-nodule cluster separation, irregular borders between tumor and non-neoplastic tissue, and an increased density of infiltrating CD11b+ cells in Group 2 animals (n = 2/3) and in all IH NanoPac-treated animals reviewed (n = 3/3 per group). A single animal in Group 4 and Group 6 exhibited signs of pathological complete response at necropsy with organizing stroma and immune cells replacing areas presumed to have previously contained adenocarcinoma nodules. Conclusion: Tumor regression and immune cell infiltration were observed in all treatment groups, with an increased incidence noted in animals receiving IH submicron particle paclitaxel treatment.

Pharmacokinetic Profile of Inhaled Submicron Particle Paclitaxel (NanoPac®) in a Rodent Model.

BACKGROUND: Inhaled chemotherapeutics may enhance pulmonary drug exposure to malignant lesions in the lung without substantially contributing to systemic toxicities. The pharmacokinetic profile of inhaled submicron particle paclitaxel (NanoPac®) in healthy rodent plasma and lung tissue is evaluated here to determine administration proof-of-principle. METHODS: Healthy male Sprague Dawley rats received paclitaxel in one of three arms: intravenous nab-paclitaxel at 2.9 mg/kg (IVnP), inhaled NanoPac low dose (IHNP-LD) at 0.38 mg/kg, or inhaled NanoPac high dose (IHNP-HD) at 1.18 mg/kg. Plasma and lung tissue paclitaxel concentrations were determined using ultraperformance liquid chromatography tandem mass spectrometry from animals sacrificed at 10 time points ranging up to 2 weeks after administration. Peak concentration (Cmax), apparent residence half-life (T1/2), exposure (AUC(last)), and dose-normalized exposure (AUCD(last)) were determined. Pulmonary histopathology was performed on rats sacrificed at the 336-hour time point. RESULTS: Paclitaxel was detectable and quantifiable in the rat lung for both inhaled NanoPac arms sampled at the final necropsy, 336 hours postadministration. Substantial paclitaxel deposition and retention resulted in an order of magnitude increase in dose-normalized pulmonary exposure over IVnP. Inhaled NanoPac arms had an order of magnitude lower plasma Cmax than IVnP, but followed a similar plasma T1/2 clearance (quantifiable only to 72 hours postadministration). Pulmonary histopathology found all treated animals indistinguishable from treatment-naive rats. CONCLUSION: In the rodent model, inhaled NanoPac demonstrated substantial deposition and retention of paclitaxel in sampled lung tissue. Further research to determine NanoPac's toxicity profile and potential efficacy as lung cancer therapy is underway.