A randomized, double-blind, placebo-controlled phase 3 skin cancer prevention study of {alpha}-difluoromethylornithine in subjects with previous history of skin cancer

Preclinical studies have shown that the inhibition of ornithine decarboxylase (ODC) by alpha-difluoromethylornithine (DFMO) and resultant decreases in tissue concentrations of polyamines (putrescine and spermidine) prevents neoplastic developments in many tissue types. Clinical studies of oral DFMO at 500 mg/m(2)/day revealed it to be safe and tolerable and resulted in significant inhibition of phorbol ester-induced skin ODC activity. Two hundred and ninety-one participants (mean age, 61 years; 60% male) with a history of prior nonmelanoma skin cancer (NMSC; mean, 4.5 skin cancers) were randomized to oral DFMO (500 mg/m(2)/day) or placebo for 4 to 5 years. There was a trend toward a history of more prior skin cancers in subjects randomized to placebo, but all other characteristics including sunscreen and nonsteroidal anti-inflammatory drug use were evenly distributed. Evaluation of 1,200 person-years of follow-up revealed a new NMSC rate of 0.5 events/person/year. The primary end point, new NMSCs, was not significantly different between subjects taking DFMO and placebo (260 versus 363 cancers, P = 0.069, two-sample t test). Evaluation of basal cell (BCC) and squamous cell cancers separately revealed very little difference in squamous cell cancer between treatment groups but a significant difference in new BCC (DFMO, 163 cancers; placebo, 243 cancers; expressed as event rate of 0.28 BCC/person/year versus 0.40 BCC/person/year, P = 0.03). Compliance with DFMO was >90% and it seemed to be well tolerated with evidence of mild ototoxicity as measured by serial audiometric examination when compared with placebo subjects. The analysis of normal skin biopsies revealed a significant (P < 0.05) decrease in 12-0-tetradecanoylphorbol-13-acetate-induced ODC activity (month 24, 36, and 48) and putrescine concentration (month 24 and 36 only) in DFMO subjects. Subjects with a history of skin cancer taking daily DFMO had an insignificant reduction (P = 0.069) in new NMSC that was predominantly due to a marked reduction in new BCC. Based on these data, the potential of DFMO, alone or in combination, to prevent skin cancers should be explored further.

In vivo priming effects of interferon-beta ser on NK activity of peripheral blood mononuclear cells in cancer patients

Natural killer (NK) activity was assayed in fresh peripheral blood mononuclear cells (PBMs) from cancer patients receiving interferon (IFN)-beta ser. Patients received a single intravenous injection of IFN-beta ser (90 x 10(6) IU m-2) on alternate days for 2 weeks, followed by a higher dose (180 x 10(6) IU m-2) on the same schedule. PBM NK lysis of K562 target cells was significantly increased in PBMs sampled 24 h after the initial injection (P < 0.05). At the end of the first 2 weeks of the protocol, NK cytotoxic activity of PBMs had fallen below the original baseline levels; the higher IFN dose subsequently given was without effect. However, significant increases in the proportion of CD16+ cells were seen following each injection. A positive correlation was also seen between the increased lytic activity of CD16+ NK cells and the proportion of CD38+ NK cells, but not the proportion of CD56+ NK cells. In vitro IFN-treatment of these in vivo-treated PBMs resulted in a further increase in NK activity. Pre-exposure in vivo to IFN-beta ser seems to prime the PBMs to respond to in vitro stimulation by IFN-gamma, which otherwise had no effect. Phenotypic analysis of PBMs after in vitro exposure to IFN-beta ser showed that the levels of CD16+, CD38+ and CD56+ cells did not change. All the NK activity responding to IFN-beta ser was found in the CD16+ enriched population of PBM, suggesting that it is unlikely that in vivo redistribution of CD16+ subsets representative of NK cells has occurred in the peripheral blood.

A phase I trial of interferon-alpha-2a plus cyclophosphamide, vincristine, prednisone, and doxorubicin

We conducted a Phase I trial of interferon-alpha-2a (IFN-alpha-2a) plus combination chemotherapy consisting of cyclophosphamide, vincristine, prednisone, and doxorubicin (COPA) in order to determine the maximum dose of IFN-alpha-2a that could be administered without compromising the dose intensity of COPA. Twenty-one patients received IFN-alpha-2a intramuscularly on days 1-5, followed by 600 mg/m2 cyclophosphamide intravenously (i.v.) on day 8; 50 mg/m2 doxorubicin i.v. on day 8; 1.2 mg/m2 vincristine i.v. on day 8; and 100 mg/m2 prednisone orally on days 8-12. IFN doses were escalated between patient groups; 7 patients received 12 x 10(6) U/m2, 11 patients received 6 X 10(6) U/M2, and 3 patients received 12 X 10(6)/m2. Because 79% of the cycles of COPA administered at the third dose level required a delay for hematologic recovery, further patient accrual at this dose level ceased. Grade III or IV granulocytopenia occurred on day 1 in 6, 9, and 0 of the patients treated at the three dose levels. Granulocyte counts rapidly recovered, however, and did not result in a delay in chemotherapy administration on day 8 in 94% of the cycles at the first two dose levels. The mean hematocrit following five cycles of therapy dropped from 40 to 31%. Only two patients required dose reductions due to constitutional symptoms related to the IFN-alpha-2a. Eight responses were observed, including five of five patients with nonHodgkin's lymphomas, one of five with melanoma, one of six with renal cell carcinoma, and one of one with adenoid cystic carcinoma. One patient with metastatic melanoma remains in a complete response on maintenance IFN-alpha-2a for three years. We conclude that 6 X 10(6) U/m2 of IFN-alpha-2a can be administered to cancer patients without significantly compromising the dose intensity of COPA. This observation, and the demonstrated activity of IFN-alpha-2a plus COPA (I-COPA) in low and intermediate grade histology nonHodgkin's lymphomas, provides the basis for the randomized Phase III trial comparing COPA to I-COPA in these neoplasms, which is currently being conducted in the Eastern Cooperative Oncology Group.

Phase II trial of interferon-beta for treatment of recurrent glioblastoma multiforme

Twelve patients were admitted to a Phase II study on the treatment of recurrent glioblastoma multiforme with interferon-beta (IFN-beta). All patients had previously undergone craniotomy and received a standard course of radiation therapy. Recurrence was inferred from enlargement of the lesion on computerized tomography (CT) scanning and in each case was confirmed by CT-guided stereotaxic biopsy. Treatment consisted of combined intravenous (10 X 10(6) IU/day) and intratumoral (1 X 10(6) IU every other day) administration of IFN-beta over three 10-day cycles. This regimen was well tolerated, with toxicity requiring temporary dose modifications in five patients. As judged from data from historical cases, however, the patients admitted to this study demonstrated no clear improvement in mean survival time. The findings of this study also emphasize the importance of distinguishing between radiation necrosis and tumor recurrence.

Phase I evaluation of a synthetic mutant of beta-interferon

A synthetic mutant of beta-interferon, produced by recombinant DNA technology, was prepared with serine substituted for the naturally occurring cysteine at amino acid 17. This molecule, after purification to homogeneity, was evaluated in 23 patients with cancer for tolerated doses, safety, and pharmacokinetics. Each patient was begun on twice weekly administration, one dose i.m., then an identical dose i.v. Doses, escalated weekly, were tolerated by 9 of 12 patients at 100 X 10(6) units i.m., 11 of 14 patients at 100 X 10(6) units i.v., and 8 of 10 patients receiving i.v. doses of 200 X 10(6) units. Fever (greater than or equal to 38.9 degrees C), the commonest cause for ceasing dose escalation, occurred in 11 of 13 patients who developed limiting i.v. toxicity and 6 of 11 who developed limiting i.m. toxicity. Patients who did not have progressive cancer after completion of dose escalation received five consecutive daily doses at their maximum tolerated single dose by each route, i.m. and i.v. These two 5-day treatments were given without difficulty. All patients treated with 300 X 10(6) units or less, i.m. (n = 13) or i.v. (n = 10), were able to receive five daily doses without limiting toxicity. Peak serum titers occurred immediately after i.v. administration and declined in an exponential manner thereafter. Despite absence of measurable titers in serum after i.m. injection, fever and significant (P less than 0.05) depression of WBC and platelet counts, serum calcium, and serum cholesterol occurred (prestudy to maximum tolerated dose). An immunoglobulin antibody to beta-interferon, detected by enzyme-linked immunoabsorbent assay, developed in 17 of 23 patients. Neutralizing activity (titer 10(2] was found in only 1 of 23 patients. No immune-mediated sequelae (symptomatic or renal) were identified. Further Phase I and II trials with this molecule will determine whether it will prove to have a better therapeutic index or different spectrum of therapeutic activity from alpha-interferon or gamma-interferon.