Ultrastructural and freeze fracture localization of multilamellar liposomes containing a lipophilic cisplatin analogue in normal tissues and liver metastases of M5076 reticulosarcoma

A Phase 2 trial of the liposomal DACH platinum L-NDDP in patients with therapy-refractory advanced colorectal cancer

PURPOSE

L-NDDP (Aroplatin) is a liposomal formulation of cis-bis-neodecanoato-trans-R,R-1,2-diaminocyclohexane platinum (II), a structural analogue of oxaliplatin. In a Phase 1 trial, the maximum tolerated dose (MTD) of L-NDDP was 312.5 mg/m2 with myelosuppression as dose limiting toxicity (DLT). We conducted a Phase 2 trial of L-NDDP in patients (pts) with advanced colorectal cancer (CRC) refractory to 5-fluorouracil/leucovorin or capecitabine and irinotecan to investigate the anti-tumor response of L-NDDP and to further characterize its toxicity profile in this population.

METHODS

L-NDDP was administered intravenously, once every 28 days. The starting dose was 300 mg/m2, with possible intra-patient dose escalation in the absence of grade 2 or higher drug-related toxicity. Patients were treated until disease progression or unacceptable toxicity. Of 20 eligible patients all were evaluable for toxicity and 18 were evaluable for response. Hematologic toxicities included anemia (grades 1-4) in 20% of pts and leucopenia, neutropenia and thrombocytopenia (grade 1/2) in 5% of patients each. Common non-hematologic toxicities included nausea (75%), vomiting (60%), and fatigue (70%), reversible infusion reactions (chest/back pain or shortness of breath; 40%), transient transaminase elevations (35%) and hyperbilirubinemia (20%). Grade 3-4 toxicities included infusion reaction (20%), vomiting (15%), fatigue (15%), anemia (10%) and ALT/AST elevation (5/15%). Peripheral neuropathy (grade 1/2) was seen in 15% of pts. One of 18 pts had a confirmed PR (5.6%), three (16.7%) had stable disease (> or =3 months) and 14 pts progressed. L-NDDP was well tolerated in this group of refractory patients and demonstrated evidence of anti-tumor activity.

CONCLUSION

Further studies of L-NDDP, preferably in combination with other agents such as fluoropyrimidines, are warranted.

Preparation and characterization of liposomes containing a lipophilic cisplatin derivative for clinical use

Cis-bis-neodecanoato-trans-R,R-1,2 diaminocyclohexane platinum(II) (NDDP) is a lipophilic cisplatin derivative that has been formulated entrapped in multilamellar liposomes composed of dimyristoylphosphatidyl choline (DMPC) and dimyristoylphosphatidyl glycerol (DMPG). A phase I clinical study with liposome-entrapped NDDP (L-NDDP) administered i.v. every 4 weeks has been recently completed. L-NDDP was synthesized, manufactured, and reconstituted for clinical use in our laboratories. L-NDDP was prepared as a lyophilized powder containing the NDDP and the phospholipids (NDDP-lipid weight ratio 1:15; DMPC-DMPG molar ratio 7:3). The liposome suspension was obtained on the day of use just before administration to the patients by adding normal saline (final concentration 1 mg NDDP/ml) and shaking in a water-bath shaker at room temperature according to an established protocol. A total of 54 batches of lyophilized L-NDDP were prepared. Physical appearance, phospholipid content and integrity, and elemental platinum content were determined in all batches and found to be reproducible. All batches contained < 0.24 ng/ml endotoxin. The amount of residual organic solvents was < 0.05 per cent. In all reconstituted doses, drug entrapment was > 90 per cent, and the proportion of liposomes measuring > 5 microns was < 20 per cent. Our results show that reproducible batches of liposomal preparations of new compounds can be prepared in the laboratory facilities of academic institutions, thus allowing for early clinical trials with novel therapeutic agents.

Hepatic tissue distribution of doxorubicin-loaded nanoparticles after i.v. administration in reticulosarcoma M 5076 metastasis-bearing mice

In our previous studies, doxorubicin-loaded polyisohexylcyanoacrylate nanoparticles have been proven to increase dramatically the antitumoral activity of the cytotoxic agent in metastasis-bearing mice. The experimental model consisted of metastases induced by i.v. inoculation of reticulosarcoma M 5076 cell suspension to C57BL/6 mice. The improved efficacy of the drug was noted in terms of either metastasis count or survival. Therefore, tissue-distribution studies of this drug delivery system within the metastatic liver after i.v. administration were undertaken to gain more insight into the mechanism of action. Doxorubicin measurements in healthy hepatic or neoplastic tissue were carried out together with histological examinations using transmission electron microscopy. These results demonstrated the hepatic tissue to be an efficient reservoir of the drug when it was injected associated with nanoparticles. Accumulation of biodegradable nanoparticles with associated doxorubicin in Kupffer cells created a gradient of drug concentration for a massive and prolonged diffusion of the free drug towards the neoplastic tissue.

Organ distribution and tumor uptake of liposome entrapped cis-bis-neodecanoato trans-R, R-1,2 diaminocyclohexane platinum (II) administered intravenously and into the proper hepatic artery

Blood and tissue levels of elemental platinum (Pt) were measured after the administration of a liposomally entrapped cisplatin analogue, cis-bis-neodecanoato-trans-R,R-1,2-diaminocyclohexane platinum (II) (L-NDDP). In mice bearing subcutaneous B16 melanoma tumors, Pt tumor levels were not significantly different in animals treated i.v. with an equimolar dose of L-NDDP or cisplatin. In rabbits bearing liver tumors of VX2 carcinoma, i.v. administration of L-NDDP resulted in 2- to 20-fold higher Pt levels in all tissues (including VX2 tumors) except the brain and peripheral nerve than in animals treated with an equimolar dose of cisplatin. Compared with i.v. administration, inoculation of either drug into the proper hepatic artery resulted in a severalfold increase of Pt levels in the VX2 tumors. Blood and other tissue levels were not substantially changed by intraarterial (i.a.) administration. These studies show that (1) multilamellar lipid vesicles can adequately deliver a lipophilic cisplatin analogue (NDDP) to nonphagocytic tumors when administered i.v. and (2) the inoculation of L-NDDP into the proper hepatic artery results in higher Pt tumor levels than with i.v. administration but does not decrease the systemic distribution of the drug.