Inhibition of metastatic renal cell carcinomas expressing somatostatin receptors by a targeted cytotoxic analogue of somatostatin AN-238

Artur Plonowski, Andrew V. Schally, Attila Nagy, Hippokratis Kiaris, Francine Hebert, Gabor Halmos

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39 Scopus citations

Abstract

The effectiveness of chemotherapy targeted to somatostatin (SST) receptors based on cytotoxic SST analogue AN-238, consisting of 2- pyrrolinodoxorubicin (AN-201) linked to SST carrier octapeptide, was investigated in human renal cell carcinomas (RCCs). SST receptors, which showed high-affinity binding for AN-238, were found in the SW-839 RCC line with sst2(A) subtype and in the 786-0 RCC line, which expressed the sst5 subtype. CAKI-1 RCC, which does not express sst2(A) or sst5, was used as a negative control for testing the specificity of SST receptor targeting. Using microsatellite analysis, AN-238 was shown to selectively inhibit the proliferation of 786-0 line, but not the CAKI-1 RCC line in vitro. The effects of three i.v. injections of 150 nmol/kg of AN-238 or AN-201, given on days 1, 8, and 21, were evaluated in groups of nude mice bearing s.c. xenografts of SW-839 and 786-0 RCC. After 5 weeks, the volumes of SW-839 and 786-0 RCC tumors were decreased by 67,2 (P < 0.05) and 78.3% (P < 0.01), respectively, whereas AN-201 had no significant effect on tumor growth. The inhibition of SST receptor-negative CAKI-1 tumors by AN-238 was only marginal. To investigate the efficacy of SST receptor-targeted chemotherapy in metastatic RCC, three i.v. injections of AN-238 or AN-201 at 150 nmol/kg were given at biweekly intervals to nude mice implanted with 786-0 tumors under the renal capsule. After 6 weeks, the weight of orthotopic tumors treated with AN-238 (55.3 ± 44.3 mg) was significantly lower (87% reduction; P < 0.001) than that in the control group (414.2 ± 41.0 mg) or in animals given AN-201 (270.2 ± 60.3 mg; P < 0.05). Five of six animals (83%), both in the control and the AN-201 group, developed metastases to lymph nodes, but only one of seven mice (14%) given AN-238 showed lymphatic spread. Lung metastases were found in 83% of controls and 50% of AN-201 treated animals, but none occurred in mice treated with AN-238. This study demonstrates that targeted cytotoxic SST analogue AN-238 provides an effective therapy for chemoresistant neoplasms such as RCC. Because most clinical RCCs express SST receptors, this treatment modality might be beneficial to patients with metastatic disease.

Original languageEnglish (US)
Pages (from-to)2996-3001
Number of pages6
JournalCancer Research
Volume60
Issue number11
StatePublished - Jun 1 2000
Externally publishedYes

ASJC Scopus subject areas

  • Oncology
  • Cancer Research

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