Octreotide neutralizes dexamethasone antitumor actions on P388 murine lymphocytic leukemia in vivo

PURPOSE

A wide variety of human malignancies, including lymphoproliferative neoplasms, express somatistatin (SS) receptors (SS-R). SS induces apoptosis and exerts pronounced antiproliferative effects on various human tumors cell lines, human xenografts, and animal tumors including P388 lymphocytic leukemia. In patients with thymoma the combination of octreotide (OCT) with corticosteroids improves the overall response rate. It has been reported that SS can increase glucocorticoid activity. Hereby, we studied the in vitro and in vivo activity of the SS analogue OCT and of the glucocorticoid dexamethasone (DEX) alone or in combination against the murine P388 lymphocytic leukemia.

MATERIALS AND METHODS

Cultures of P388 lymphocytic leukemia and BDF(1) male mice implanted with P388 cells where used for the in vitro an in vivo evaluation of the antileukemic activity of SS and DEX.

RESULTS

OCT induced a moderate and DEX a satisfactory cytostatic effect in vitro. OCT produced borderline antileukemic effect when administered on days 1-5 while DEX was effective in all schemes and routes of administration. However, none of the combination schemes exerted any anti-leukemic activity both in vitro and in vivo.

CONCLUSION

Since both SS and glucocorticoids exert direct (via receptors) and indirect antitumor actions (regulation of growth factor activity) on several cell lines, in vitro and in vivo, it becomes obvious that further in vitro studies shall provide the molecular evidence for the signal transduction pathways which are involved in the interactions of such important anticancer drugs. Based on the results of the present study, the simultaneous use of these drugs in clinical practice should be carefully considered.

Antitumour effect of a- and d- lactam androgen nitrogen mustards on non-small cell lung carcinoma

PURPOSE

We tested 3 alkylating esters of D-lactam androsterone, 3 alkylating esters of A-lactam testosterone and the alkylating nitrogen mustard components of these esters, for antineoplastic activity on non-small cell lung carcinoma (NSCLC) in vitro and in vivo.

MATERIALS AND METHODS

Cytostatic and cytotoxic activity was evaluated in vitro against 10 human NSCLC cell lines. The in vitro testing was performed with the MTT metabolic-colorimetric assay and the mean concentrations of each drug that generated 50% or total (100%) growth inhibition (GI50 and TGI, respectively) as well as the drug concentrations that produced cytotoxicity against 50% of the cultured cells (IC50) were calculated. Furthermore, the in vivo antitumour effect was determined against the relatively chemo-resistant Lewis lung carcinoma (LLC) on mice. The acute toxicity of the tested compounds was appointed in C57BL mice and the antitumor effect on LLC was assessed from the percent increase in median lifespan of the treated animals over the untreated (control) (T/C%).

RESULTS

The lactam steroidal esters presented lower toxicity and increased antineoplastic activity in vitro and in vivo compared to their respective alkylating components. An A-lactam testosterone ester namely: 17beta-hydroxy- 3-aza-A-homo-4alpha-androsten-4-one-p-N,N-bis (2chloroethyl) amino phenoxy acetate (ALT-CAPOA) performed significantly higher anticancer activity in vitro and in vivo. This compound generated 37.5% 90-day disease free survivors (cures) against LLC.

CONCLUSION

These results indicate a high antitumor potential of lactam steroid alkylating esters depended on the alkylating moiety as well as on the modified steroidal carrier. Preclinical research supports that ALT-CAPOA generates well-tolerated toxicity as well as superior antitumor activity against NSCLC. These significant results call for further clinical development.