Preclinical studies/trials

Most recently, a phase-I-study defined a dose of 13-ris-retinoic acid that was tolerable in patients after myeloablative therapy, and a phase-III-trial showed that postconsolidation therapy with 13-cis-retinoic acid improved EFS for patients with high-risk neuroblastoma [7]. Preclinical studies in neuroblastoma indicate that ATRA or 13-cw-RA can antagonize cytotoxic chemotherapy and radiation, such that use of 13-cis-RA in neuroblastoma is limited to maintenance after completion of cytotoxic chemotherapy and radiation. It is likely that recurrent disease seen during or after 13-cis-RA therapy in neuroblastoma is due to tumor cell resistance to retinoid-mediated differentiation induction. Studies in neuroblastoma cell lines resistant to 13-cw-RA and ATRA have shown that they can be sensitive, and in some cases collaterally hypersensitive, to the cytotoxic retinoid fenretinide. Here, fenretinide induces tumor cell cytotoxicity rather than differentiation, acts independently from RA receptors, and in initial phase-I-trials has been well tolerated. Clinical trials of fenretinide, alone and in combination with ceramide modulators, are in development. 

Droloxifene (3-hydroxy-tamoxifen) behaves as an estrogen agonist in bone tissue and several lipid and coagulation markers in castrated rat models and does not show stimulation of the endometrial epithelium in preclinical studies (Ke et al. 1997). Endometrial stimulation has, however, been observed in clinical trials, which, together with the fact that as an estrogen agonist it is ten times less potent than tamoxifen in bone tissue and lipid metabolism (Hendrix et al. 2001) and that in a recent head-to-head comparison with tamoxifen droloxifene was demonstrated not to be superior in any parameter of breast cancer treatment efficacy (Buzdar et al. 2002), has resulted in cancellation of its clinical development. 

Priliximab (cM-T412) is an anti-CD4 chimeric monoclonal antibody that was evaluated in the clinic for the treatment of autoimmune diseases. Priliximab binds to CD4 on the surface of T cells and leads to a profound and sustained decrease in circulating CD4+ T cells decreased counts have been reported to be below normal levels at 18 and 30 months following single- and multiple-infusions.81 Similar findings were observed in preclinical studies in chimpanzees.82 The administration of priliximab was also associated with a cytokine-release syndrome that caused transient fever, myalgia, chills, headache, nausea, and/or hypotension that was accompanied by an increase in serum IL-6. Although evidence of efficacy was observed in clinical trials for CD, the... 

The overexpression of GSTs in some cancer cells, particularly of GST Pl-1, offers an opportunity to detect and treat some cancer types (e.g., ovarian cancer). Recent developments in the design of small molecules that either inhibit the catalytic activity of GST Pl-1 or use GST Pl-1 catalytic site to release the actual anticancer agent, have shown promising results in preclinical studies, with the graduation of 66 and 96 as potential anticancer drug candidates currently undergoing clinical trials. 

Preclinical studies should address the potential toxicity due to inappropriate release of the conjugated toxin. Preclinical toxicology of monoclonal antibodies may not require extensive animal studies but should be examined for cross-reactivity with antigenic epitopes present on normal cells in vitro and for the presence of human or rodent vimses. Early clinical trial should involve biodistribution studies with radiolabelled material. 

Local clinical trial may be waived by the licensing authority in the interest of the public good, in which case data from preclinical studies are to be evaluated. TTie approval for import permission is given on Form 45 or 45A, clinical trial on Form 46 and/or 46A, and new bulk drug substance on Form 54a. 

Both vincristine and vinblastine are administered by intravenous injection, and this reflects the relatively poor bioavailability of the drugs indicated in preclinical studies. Oral administration of a vinblastine derivative, vinzolidine (Fig. 2), has been shown to produce some antitumor activity in clinical trials, but investigations of this oral agent have been discontinued because of unpredictable toxicity (50). 

Muggia FM, Creaven PJ, Hansen HH, Cohen MH, Selawry OS. Phase I clinical trial of weekly and daily treatment with camptothecin (NSC-100880) correlation with preclinical studies. Cancer Chemother Rep 1972 56(4) 515-521. 

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