High anti-tumor activity of a novel alpha-fetoprotein-maytansinoid conjugate targeting alpha-fetoprotein receptors in colorectal cancer xenograft model.

The alpha-fetoprotein receptor (AFPR) is a novel target for cancer therapeutics. It is expressed on most cancers and myeloid derived suppressor cells (MDSCs) but generally absent on normal tissues. Studies were performed to investigate the use of recombinant human AFP (ACT-101) conjugated with maytansinoid toxins for targeted toxin delivery to cancer. Four structurally different ACT-101-maytansinoid conjugates containing cleavable glutathione sensitive linkers were initially investigated in a mouse xenograft model of colorectal cancer. Reduction in tumor volume was seen for all four conjugates compared to control (p < 0.05). The anti-tumor effects of the conjugate selected for further development (ACT-903) persisted after treatment discontinuation, with tumors becoming undetectable in 9 of 10 mice, and all 10 mice surviving through Day 60 with no obvious signs of toxicity. A follow-up study performed in the same model compared the effects of single intravenous doses of ACT-903 (10-50 mg/kg) to that of control groups receiving vehicle or ACT-101. A significant reduction of tumor burden compared to control was achieved in the 40 and 50 mg/kg dose groups. Survival was significantly prolonged in these 2 groups (40 mg/kg (p < 0.0001); 50 mg/kg (p = 0.0037). Free maytansine blood levels at 4 h were 0.008% of the dose, indicating stability of the conjugate in circulation as was expected based on in vitro plasma stability studies. No obvious signs of toxicity were seen in any of the treated groups. Observed efficacy and excellent tolerability of ACT-903 in these xenograft models support advancing the development of ACT-903 toward clinical use.

Comprehensive approach to cancer immunotherapy - Simultaneous targeting of myeloid-derived suppressor cells and cancer cells with AFP conjugates.

The immune system plays a pivotal role in combating diseases, including cancer, with monocytes emerging as key regulators of immune response dynamics. This article describes a novel strategy for cancer treatment centered on depleting myeloid-derived suppressor cells (MDSCs), to enhance the overall immune response while simultaneously targeting cancer cells directly. Alpha-fetoprotein (AFP) is an oncofetal protein that plays an important role in delivering nutrients to immature monocytes, embryonic, and cancer cells in a targeted manner. AFP can be repurposed, making it a vehicle for delivering toxins, rather than nutrients to kill cancer cells and deplete MDSCs in the tumor microenvironment (TME). Depleting monocytes not only stimulates the immune system but also improves the lymphocyte-to-monocyte ratio (LMR), often low in cancer patients. AFP combined with cytotoxic drugs, offers dual benefit-immune stimulation and targeted chemotherapy. Studies in xenograft models demonstrated high efficacy and safety of AFP-toxin conjugates, surpassing conventional targeted chemotherapy. Such conjugates have also been reported to provide superior efficacy and safety in cancer patients compared to chemotherapy. This approach, using AFP conjugated with toxins, either covalently or non-covalently, presents a safe and highly effective option for cancer immuno/chemotherapy.

Pharmacokinetics studies and toxicity profile of raltitrexed used by intraperitoneal route in normothermia in a pig model.

BACKGROUND: To define the pharmacokinetic and toxicity profile of raltitrexed administered by intraperitoneal route in a normothermic pig model. MATERIAL/METHODS: Twenty-one female pigs were divided in three groups. Under general anesthesia, pigs in groups 1 and 2 underwent laparotomy with resection of a small hepatic wedge, bowel anastomosis and portal and systemic vein catheterization. This was followed by an intraperitioneal delivery of raltitrexed: a dose of 1 mg was given to group 1 pigs, whereas group 2 received 2 mg. Serial sampling of portal blood, systemic blood and peritoneal fluid was then undertaken in both groups for pharmacokinetics studies. Pigs were followed daily for a period of 10 days after surgery with recordings of signs of toxicity. On day 10, an exploratory laparotomy was undertaken on each pig in order to assess peritoneal toxicity after which they were euthanized. Pigs in group 3 were used for bioavailability evaluation. RESULTS: Three deaths were recorded within 24 hours of surgery; a technical problem was identified in all cases and no deaths were the results of raltitrexed toxicity. A peritoneo-plasma gradient of 100:1 was obtained. Cmax in plasma were of 28 ng/ml and 54 ng/ml for group 1 and 2, respectively. Tmax were 180 min for both groups. AUCplasmatic was double in the 2 mg group compared to the 1 mg group. CONCLUSIONS: Raltitrexed administered by IP route in pigs is non-toxic. Pharmacologically, there are few interindividual variations and the small first-past effect did not significantly alter the high peritoneo-plasmatic gradient