Influence of treatment sequence on efficacy of fluorouracil and cisplatin intratumoral drug delivery in vivo.

PURPOSE: The influence of treatment sequence in combination chemotherapy using fluorouracil (5-FU) and cisplatin (CDDP) was investigated in a mouse tumor model. Both drugs were formulated as therapeutic injectable gels, 5-FU/epinephrine gel and CDDP/epinephrine gel, and used intratumorally in a multiple-treatment regimen. By testing various multiple-treatment regimens, we determined optimal treatment sequences for these two injectable gels. Then we compared the antitumor responses achieved using the optimal treatment sequences for the intratumorally administered gels with the responses obtained using 5-FU and CDDP solutions administered intratumorally or systemically in the same treatment sequence. MATERIALS AND METHODS: Tumor-bearing C3H mice received a total of four injections (every 2 to 3 days from day 0 through day 7) of 5-FU solution, CDDP solution, 5-FU/epinephrine gel, or CDDP/epinephrine gel either as single agents or in various combinations and alternate sequences of solutions or gels. The delay in tumor growth was used as a study end-point. RESULTS: The results showed that local treatment (i.e., intratumoral administration) was more efficacious than systemic treatment (i.e., intraperitoneal administration) when both 5-FU solution and CDDP solution were used either alone or in combination. Further, using two drugs in combination was superior to using either drug alone. When both drugs were delivered intratumorally in the injectable gel formulations, the combination treatment sequences initiated with 5-FU/epinephrine gel were superior to sequences initiated with CDDP/epinephrine gel in delaying the tumor growth. The two sequences initiated with 5-FU/epinephrine gel (i.e., two treatments with 5-FU/epinephrine gel followed by two treatments with CDDP/epinephrine gel and the sequence of alternating 5-FU/epinephrine gel and CDDP/epinephrine gel) showed no significant difference in antitumor efficacy. Both these sequences (initiated with 5-FU/epinephrine gel) produced the longest delays in tumor growth, and > or = 50% (7 of 12) animals remained disease free at the end of the 60-day study. CONCLUSION: These studies demonstrate that significant improvement in local tumor control in mice can be achieved with a simple treatment sequence alteration of two established drugs.

Antitumor effect of intratumoral administration of fluorouracil/epinephrine injectable gel in C3H mice.

Fluorouracil/epinephrine injectable gel (5-FU/epi gel) was evaluated in vitro for its drug-release profile characteristics and in a mouse tumor model for its antitumor effectiveness. In vitro chemosensitivity studies with 5-FU in RIF-1 fibrosarcoma cells showed less than 1 log of cell kill at 1 mM after 2 h of exposure. Increasing the exposure time to 24 h resulted in greater cell killing (approximately 2.5 log cell kill at 0.5 mM), suggesting that sustained drug levels in tumors would result in an increased efficacy outcome in vivo. A 5-FU/epi injectable gel was designed, providing drug release in vitro of 50% by approximately 4 h and of 80% by 24 h. The retention of 5-FU in RIF-1 mouse tumors was determined after intratumoral administration of 5-FU/epi gel or various combinations of the formulation components. Area-under-the-curve (AUC0-24 h) calculations resulted in an AUC value of 146.4% h for the 5-FU/epi gel formulation as compared with 45.7% h for 5-FU solution. Tumor growth was significantly delayed (P < 0.05) with the 5-FU/epi gel (60 mg/kg) as compared with 5-FU solution given intratumorally or systemically. A fluorouracil dose of 150 mg/kg in the 5-FU/epi gel given weekly for 13 weeks was not lethally toxic, whereas the same dose given as drug solution was 100% lethal, suggesting that the therapeutic index for 5-FU in the gel formulation may be much greater than that for aqueous drug solution delivered intratumorally.

Intralesional implant for treatment of primary oral malignant melanoma in dogs.

The feasibility, safety, and efficacy of a new method of local, sustained-release chemotherapy by use of intralesional cisplatin implants were evaluated in the treatment of oral malignant melanoma. The implant is an injectable viscous gel composed of a protein carrier matrix, a vasoactive modifier, and a chemotherapeutic drug. Twenty dogs with biopsy-proven melanomas were treated at 1- to 2-week intervals by injection with cisplatin implant. Tumors were treated until they resolved or were judged to be unresponsive. In 3 dogs with tumors unresponsive to cisplatin implants, methotrexate implants were used, and in 2 of these dogs, carmustine implants followed the methotrexate. Tumor responses were evaluated by sequential measurements. Melanomas in 14 (70%) of 20 dogs had a > 50% decrease in volume, and in 11 (55%) of these dogs, had a complete response. Tumors with complete responses received a mean cisplatin dose of 11.7 +/- 1.8 mg, delivered in a mean of 2.6 treatments. Two of the dogs with complete response also were treated with methotrexate and carmustine. Implants were well tolerated. Local necrosis, limited to the treatment site, developed in most tumors (17/20) and was associated with tumor response. Systemic toxicosis was minimal; renal insufficiency after cisplatin implants was not evident. Median survival times of dogs with complete tumor response (51 weeks) was substantially greater than that of dogs without local tumor control (10.5 weeks). Recursive partitioning analysis of variables indicated that mandibular tumors of short duration were associated with a positive outcome.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of intralesional 5-fluorouracil therapeutic implant (MPI 5003) for treatment of basal cell carcinoma.

BACKGROUND: Basal cell carcinomas (BCCs) are usually treated with ablative procedures. A nonsurgical treatment alternative would be of value in selected patients. OBJECTIVE: We evaluated the safety and efficacy of a new preparation for intralesional sustained-release chemotherapy with MPI 5003, 5-Fluorouracil Therapeutic Implant, for treatment of BCCs. METHODS: Two doses of intralesional MPI 5003 (0.25 and 0.5 ml) were compared in a double-blind study of 20 patients with biopsy-proven BCC. One BCC per patient was treated weekly for up to 6 weeks and followed up monthly for 3 months until excisional biopsy for histologic examination. Before excision the cosmetic appearance of the test site was graded. RESULTS: Eighty percent of 10 BCCs treated with 0.5 ml of MPI 5003 had histologically confirmed cures as compared with 60% of 10 tumors treated with the lower dose (0.25 ml). Cosmetic assessments before excision were typically good to excellent. No systemic side effects occurred. CONCLUSION: Results indicate the potential of MPI 5003 for targeted local chemotherapy for BCC.

Malignant melanoma in the foot of a horse.

A 24-year-old horse had a malignant melanoma of the right forefoot. Because surgical excision of the melanoma was incomplete, as determined by histologic examination of the excised tissue margins, the tumor margins were injected with a matrix therapeutic implant containing cis-diamminedichloroplatinum, epinephrine, and purified bovine collagen matrix. The foot healed and the horse remained clinically free of disease for 26 months before recurrence of malignant melanoma. Surgical exploration of the digit revealed extensive involvement of the foot, and the horse was euthanatized.

Improvement of differential toxicity between tumor and normal tissues using intratumoral injection with or without a slow-drug-release matrix system.

The therapeutic effects of cisplatin on tumor and normal tissues were assessed when the drug was given by different administration routes either as free drug or associated with a collagen-based matrix. Tumor response was assessed by growth delay of the murine RIF1 tumor, grown subcutaneously in female C3H/km mice. Normal tissue responses were assessed by plasma clearance of [51Cr]EDTA (giving an estimate of kidney damage), by the drop in peripheral white blood cells, and by a loss in mouse body weight. Intraperitoneal injections of cisplatin were the most toxic to the normal tissues for a given drug dose. Intratumoral injections of matrix-associated drug were the least toxic. Comparison of tumor growth delays for a given normal tissue damage demonstrated the superiority of all intratumoral schedules over the ip route.

Response of murine tumors to matrix-associated cisplatin intratumoral implants.

The response to collagen matrix-associated cisplatin (cis-DDP-CM) implanted intratumorally into KHT and RIF-1 fibrosarcomas grown sc in C3H mice was studied. The effects on tumor growth as well as body weight and animal survival were assessed. The effect of cis-DDP-CM (8 mg/kg) on the growth of KHT tumor was assessed by determining the number of days required for tumors to grow to three times the pretreatment volume of 100-150 mm3. When cisplatin (cis-DDP) was administered ip, the number of days required for threefold growth was 11.1 +/- 2.5 SE. Administration of cis-DDP-CM intratumorally resulted in a value of 17.2 +/- 1.7 days. Epinephrine (0.1-5.0 mg/kg) was also added to the matrix as a vasoconstrictor to further localize the activity of cis-DDP. This resulted in enhanced antitumor activity and, presumably, lower systemic exposure to cis-DDP. For cis-DDP administered ip, the dose required to kill 50% of the test group at 10 days after injection was approximately 14 mg/kg. When cis-DDP-CM was administered intratumorally in doses less than or equal to 30 mg/kg, no mice died. Loss in mouse body weight (greater than 3 g) was detected with ip doses of cis-DDP at 8 mg/kg, but no weight loss was detected for mice treated with matrix implant delivering cis-DDP doses less than or equal to 25 mg/kg.

Effects of matrix-associated chemotherapy in combination with irradiation in vivo.

Delay of tumor growth in RIF-1 fibrosarcomas in C3H mice was studied, comparing ip delivery of 5-fluorouracil (5-FU) or cisplatin (cis-DDP) versus collagen matrix-associated intratumoral delivery of drug with and without irradiation to a total dose of 1,500 cGy. For cis-DDP (6 mg/kg), the number of days required for treated tumors to attain three times their original treatment volume was 6.2 +/- 1.6 SE for ip drug and 7.0 +/- 1.3 for intratumoral drug matrix. The use of the vasoactive agent epinephrine (1 mg/kg) in the matrix resulted in a growth delay of 10.1 +/- 2.0 days. Irradiation given 60 minutes after drug administration enhanced the delay of tumor growth to 19.2 +/- 2.6 days for systemic drug and 16.7 +/- 2.5 days for matrix-associated drug. The delay of tumor growth for irradiation plus matrix-associated cis-DDP containing epinephrine was 33.0 +/- 5.4 days. X-rays alone caused a tumor growth delay of 11.2 +/- 1.3 days. Similar results were found for 5-FU at a dose of 50 mg/kg, although the epinephrine in the matrix was not as effective.

Chemosensitivity of human neoplasms with in vitro clone formation. Experience at the University of Southern California - Los Angeles County Medical Center.

We analyze experience with 600 specimens for in vitro chemosensitivity assessment of human neoplasms utilizing a soft agar colony-forming technique. Good test reproducibility is demonstrated. Disaggregation with collagenase enhances yield and does not alter chemosensitivity profiles. Therapeutic exposure to chemotherapy prior to biopsy reduces in vitro sensitivity to the specific agents used in vitro. The cyclophosphamide derivatives 4-hydroperoxycyclo phosphamide (4-HC) and phosphoramide mustard are active in vitro, and produce comparable rank order sensitivities among tested tumors. There is marked reduction of in vitro 4-HC sensitivity in patients with prior therapeutic cyclophosphamide exposure, supporting the use of this derivative in test systems. Rank order of test results among specimens is compared at 0.1 microgram and 10 microgram drug/ml. Substantial differences in rank order at these two dose levels are demonstrated, indicating that the in vitro test dose selected is an important variable.