Daniel F. Hoth

Metastatic renal cancer treated with interleukin-2 and lymphokine-activated killer cells. A phase II clinical trial.

STUDY OBJECTIVE To confirm the antitumor efficacy of treatment with interleukin-2 and lymphokine-activated killer cells in patients with metastatic renal cancer. DESIGN Nonrandomized, phase II clinical trial. SETTING Tertiary care units in university medical centers. PATIENTS Consecutive trial of 35 patients with metastatic or unresectable renal cell cancer who have bidimensionally measurable disease, performance status 0 or 1, and normal function of all vital organs. Thirty-two patients completed interleukin-2 priming and received at least one lymphokine-activated killer cell infusion. Three patients were removed from the study and did not receive infusion of cells secondary to rapid tumor progression or toxicity. INTERVENTIONS Patients initially received recombinant interleukin-2, 100,000 units/kg body weight every 8 hours, on days 1 to 5 in a priming phase to stimulate lymphokine-activated killer cell precursors and effector activity in vivo. Leukapheresis was done on days 8 to 12 and lymphocytes were cultured in vitro with interleukin-2 for 3 to 4 days to amplify lymphokine-activated killer cell activity. Finally, interleukin-2, 100,000 units/kg every 8 hours, was infused with cultured cells on days 12 to 16. All doses of interleukin-2 and lymphokine-activated killer cells were administered in intensive care units. MEASUREMENTS AND MAIN RESULTS The mean number of doses of interleukin-2 administered during the priming phase was 12.9 +/- 0.4; the mean number of lymphokine-activated killer cells reinfused was 7.0 +/- 0.6 X 10(10); and the mean number of interleukin-2 doses administered during the last phase was 10.2 +/- 0.6. The overall objective response rate was 16%; two patients had complete responses and three patients had partial responses with greater than 50% reduction of all measurable tumor. The complete responders remain disease-free at 12 and 9 months. Two partial responders have not had tumor regrowth at 16 and 15 months. The third partial responder relapsed at 4 months. Toxicity was severe but generally of short duration and manageable. There were no treatment-related deaths. Hypotension, weight gain, anemia, and elevations of serum creatinine levels and liver enzymes were common. Two patients required intubation; one patient had a myocardial infarction. CONCLUSIONS This phase II study confirms the antitumor activity of interleukin-2 and lymphokine-activated killer cell therapy in patients with metastatic or unresectable renal cell cancer. Response rates, especially complete remission rates, are comparable or better than rates achieved with other forms of therapy.

5-Fluorouracil, doxorubicin, and mitomycin (FAM) combination chemotherapy for advanced gastric cancer.

Sixty-two patients with advanced measurable gastric cancer were treated with a combination chemotherapy program of 5-fluorouracil, doxorubicin, and mitomycin (FAM). Forty-two percent of patients achieved an objective partial response. The median duration of remission was 9 months and the median survival for responding patients, 12.5 months. The median survival for nonresponding patients was 3.5 months; all patients were dead by 8 months after initiation of therapy. The median survival of all 62 patients treated with FAM was 5.5 months. An analysis of possible prognostic variables including initial performance status, resectability of the primary gastric tumor, and histologic differentiation of the neoplasm failed to account for differences in patient response and survival. The FAM regimen was well tolerated, producing only moderate bone marrow suppression. These results show that patients with metastatic gastric cancer can be effectively palliated with FAM chemotherapy. The efficacy of this regimen should now be tested in patients with less advanced stages of this disease.

Results of NCI-sponsored phase I trials with carboplatin.

Carboplatin has been developed for clinical trials as a less nephrotoxic, less emetogenic analog of cisplatin. In preclinical tumor models it was less potent than the parent compound on a molar basis, but reduced toxicity allowed comparable antitumor doses to be given. In phase I studies its dose-limiting toxicities were reversible myelosuppression, especially thrombocytopenia. Leucopenia and anemia occurred to a lesser degree. Other reported toxicities included nausea, vomiting, malaise, myalgia, arthralgia, ototoxicity, hypomagnesemia, and proteinuria. Nausea and vomiting occurred frequently, but was much less severe than that observed with cisplatin. The incidence of serum creatinine elevations was low. The increase was usually reversible and occurred only in association with administration of aminoglycosides, or abnormal pretreatment renal function. Recommended phase II doses by schedule are: bolus every 4 weeks, 400-500 mg/m2 (560 mg/m2 in children); 24 hour continuous infusion every 4 weeks, 320-400 mg/m2; weekly bolus for 4 consecutive weeks with 2 weeks rest, 100-125 mg/m2 (175 mg/m2 in children); bolus for 5 consecutive days every 4 weeks, 77-95 mg/m2. Objective responses were observed during these phase I studies in adult patients (head and neck, breast, renal carcinomas) and children (osteosarcoma, brain stem lesions). In addition to phase II evaluations in all major tumor types, plans for phase III studies in selected tumors are underway.

Surrogate Markers in AIDS: Where Are We? Where Are We Going?

Excerpt During the last several years, extensive research has been done on surrogate markers in patients with the acquired immunodeficiency syndrome (AIDS) (1). However, many questions remain about...

HIV Vaccine Development: A Progress Report

Dr. Daniel F. Hoth (formerly, Division of AIDS, National Institute of Allergy and Infectious Diseases [NIAID], National Institutes of Health [NIH], Bethesda, Maryland): The worldwide human immunodeficiency virus (HIV) epidemic continues to grow. In the United States, it is estimated that one new HIV infection develops every 9 or 10 minutes [1]. The Centers for Disease Control and Prevention (CDC) estimates that some 1 million HIV infections have developed in the United States. In addition, by the end of 1993, 361 164 cases of the acquired immunodeficiency syndrome (AIDS) and 220 736 AIDS-related deaths had been reported in the United States (CDC Quarterly Surveillance Report hotline, available by calling 404-332-4570). The CDC projects that by the end of 1994 there will be 415 000 to 535 000 cumulative AIDS cases and 320 000 to 385 000 AIDS-related deaths. Even more devastating are projections by the World Health Organizations (WHO) Global Programme on AIDS [2], which estimates that as of 1992, at least 8 to 10 million adults were infected with HIV and about 1 million children were born with it. The WHO conservatively projects that by the year 2000, 30 to 40 million people will develop HIV infection, more than 90% of them in developing countries. Epidemiologists from the Harvard School of Public Health [3] project even higher numbers than those of the WHO, especially for Southeast Asia and Africa. The need for intervention is clear. The public health strategy for preventing and controlling HIV infection depends on changing human behavior to reduce illicit drug injection, needle sharing [4], and the number of unprotected sexual encounters and sexual partners [5]; protecting the blood supply; expanding the diagnosis and treatment of other sexually transmitted diseases [5]; achieving optimal prenatal care for pregnant HIV-infected women; and improving the availability of and compliance with the types of antiviral chemotherapy that reduce seminal viral burden and probably infectiousness [6]. In impoverished developing nations, preventive measures remain largely unavailable, unaffordable, or unpopular [7]. Changes in human sexual behavior are possible but may require intense intervention that may not be practical or affordable in all risk settings [8]. An affordable, available HIV vaccine remains the single most important long-term goal of prevention research [9-11] to supplement expanded education on HIV infection and sexually transmitted diseases, condom marketing, sexually transmitted disease control, prevention and treatment of injection drug use, and development of new barriers to HIV acquisition [12-14]. The human immunodeficiency virus is unlike other viruses that have been successfully prevented by vaccination. Several factors favor control of HIV by vaccination: The virus is limited to a human host with no known animal reservoir; it is not highly infectious; and natural infection generates both antibody and T-cell responses. However, HIV also has many characteristics that make vaccine development difficult: subclinical cases and a carrier state, a long-term infection process, a nonspecific acute clinical disease, significant antigenic variation, viral DNA integration into the host genome, transmission through infected cells, and destruction or alteration of immunoregulatory cell function. For many patients, the first recognizable clinical manifestations of HIV are opportunistic infections that are secondary to immunodeficiency and that may develop years after initial infection. Despite these daunting scientific challenges, significant progress has been made in preclinical and clinical research in the worldwide effort to develop an effective HIV vaccine. We present a brief review for medical readers unfamiliar with HIV vaccinology. Preclinical Vaccine Research Dr. Dani P. Bolognesi (Center for AIDS Research, Duke University, Durham, North Carolina): Contemporary viral vaccines usually work by imitating natural immune responses to pathogens to eventually clear the infection [15]. Most licensed viral vaccines are based on either attenuated forms of the virus or whole inactivated preparations of the agents. A notable exception is the recombinant hepatitis B vaccine, but this also was designed to mimic a natural protective immune response [16]. Because there are no established correlates of protection and no established natural protective immunity to HIV infection, the use of attenuated or whole inactivated virus vaccines is less certain as a strategy. Moreover, these approaches raise obvious safety concerns. Further, HIV presents unprecedented obstacles for vaccine developers because it can be transmitted as a cell-associated virus across mucosal surfaces, it can hide from immune attack by establishing latent infections, and it can escape from existing immunity by generating several antigenic variants. Sequestration of the virus into immunoprivileged sites such as the central nervous system or certain lymphoid organs also appears to be an important feature of pathogenesis [17]. Attenuated and whole inactivated vaccine products, along with many recombinant DNA, protein, and peptide approaches, have been studied in various animal models of HIV infection, including HIV itself and related viruses such as simian immunodeficiency virus or feline immunodeficiency virus. The results present a complex picture. Some studies with attenuated and whole virus vaccines have shown promise in simian immunodeficiency virus and feline immunodeficiency virus models, whereas recombinant approaches have been far less effective. However, when studied in the chimpanzee model of HIV infection, recombinant subunit vaccines involving parts of the HIV envelope have effectively protected animals from infection, whereas whole inactivated virus preparations were ineffective [18]. Although more direct comparisons of each of the vaccine strategies should bring this picture into sharper focus, there are several possible reasons for the disparate results. The most important of these are differences among the animal models. Infection with feline immunodeficiency virus and simian immunodeficiency virus leads to disease in cats or monkeys, respectively, whereas HIV infection of chimpanzees does not. This difference may be due, at least in part, to the vigor with which the infection is established and thereby the potency of the vaccine required for protection. It would appear that human HIV infection associated with a long disease-free interval may represent a middle ground between the rapid disease induced by some feline immunodeficiency virus and simian immunodeficiency virus strains and the indolent HIV infection of chimpanzees. It has been suggested that infection of monkeys with simian immunodeficiency virus strains that induce a slower onset of disease may be more relevant than any model now widely used in HIV research. It is interesting to note that recombinant approaches have proved effective in at least one experiment that used the slower simian immunodeficiency virus model [19]. The reasons for the failure of whole inactivated virus vaccine to protect chimpanzees (attenuated vaccines have not been widely tested) are not entirely clear [20]. One possible explanation relates to the role of human cellular antigens associated with killed virus preparations used for vaccination and virus challenge stocks. Studies have recently shown that such antigens play a major role in protection [21]. Similar antigens may play a lesser role in chimpanzee models, but this has not been tested directly [22]. When a short-term model for simian immunodeficiency virus infection and disease is used, the attenuated virus vaccine has provided the most impressive protection [23]. Previous infection (about 2 years earlier) with a genetically modified virus that replicates poorly in monkeys and does not cause disease allowed animals to resist challenge with a relatively large dose of highly pathogenic simian immunodeficiency virus [23]. It should be possible to take full advantage of this model to derive insights on correlates of protection. Because this approach involves infection with a retrovirus, studies should include potential nonimmune correlates, such as production of inhibitory cytokines or other factors as well as the phenomenon of in vivo viral interference, to achieve the broadest scope in a search for protection correlates. Vaccine manufacturers have relied on two general factors in selecting candidates for development: safety considerations and results in chimpanzees who received candidate vaccines that were based on HIV itself. Consequently, manufacturers have largely shied away from inactivated or live attenuated vaccines and have relied on studies in chimpanzees in which vaccines based on various configurations of the HIV envelope could protect against infection. These were feasibility studies only, however, and did not examine the duration and breadth of protection or the efficacy of vaccines against various modes of virus transmission. Several features of the HIV envelope are considered potentially troublesome. Studies in vitro indicate that the native envelope can induce T-cell anergy and even death by apoptosis if certain conditions are met [24, 25]. Regions of molecular mimicry with normal-cell surface antigens, notably major histocompatibility complex (MHC) gene products, could induce autoantibodies [26]. Such properties suggest that the HIV envelope might be immunosuppressive and possibly pathogenic. Fortunately, considerable experience with more than 1600 persons not infected with HIV who received envelope-based vaccines has not shown evidence of immunosuppression. Nonetheless, the appearance of autoantibodies, antibodies that might enhance infection, or more subtle T-cell defects should continually be carefully monitored in vaccine trials. The absence of guiding principles for immune correlates of protection notwithstanding, challenges that

Flavone acetic acid (LM 975, NSC 347512) A novel antitumor agent

SummaryFlavone acetic acid (FAA) is a synthetic flavonoid compound which has recently begun clinical trials as an antitumor agent based on its striking activity in solid tumor model systems. The pharmacologic behavior of FAA in animals appears to be predictive of both its cytotoxic efficacy and its toxicity to normal tissues (principally the central nervous system and gastrointestinal tract). The design and conduct of phase I studies in man are based upon these principles, with the goal of maximizing their safety and efficacy.

Hexamethylmelamine: a critical review of an active drug.

Hexamethylmelamine is an s-triazine that began clinical trials during the 1960s based on its level of antitumor activity in murine tumor models. Phase I studies were performed using an oral formulation given in divided doses for varying numbers of days. The most frequently reported toxicities included nausea, vomiting, abdominal cramps, anorexia, weight loss and malaise. Less frequently reported toxicities were anemia, thrombocytopenia, leucopenia and peripheral neuropathy. Clinical antitumor activity was noted in the phase I studies in a variety of tumor types. Since then a large number of studies have been performed using hexamethylmelamine as a single agent and in a variety of combinations. Unfortunately, almost none of these studies sought to define the utility of this drug relative to other treatments for the diseases in which it showed activity, or to define the contribution of this drug to the activity of any given combination. Thus its role in the treatment of patients with malignancies remains undefined.

Arabinosyl-5-azacytosine: A novel nucleoside entering clinical trials

Arabinosyl-5-azacytosine is a new compound which has been selected by the Division of Cancer Treatment, National Cancer Institute for clinical development as an antineoplastic agent based on its high degree of activity against a broad range of tumor types in preclinical studies. Therapeutic activity has been observed against murine and human leukemias, transplantable murine solid tumors, and human tumor xenografts. Arabinosyl-5-azacytosine exhibited a broader spectrum of activity against human solid tumors than cytosine arabinoside. Arabinosyl-5-azacytosine is phosphorylated to the nucleotide level by deoxycytidine kinase. Upon further anabolism to the triphosphate level, it can be incorporated into DNA. The mechanism of cytotoxicity is thought to be related to inhibition of DNA synthesis. Leukemic and solid tumor cell lines that are resistant to cytosine arabinoside due to deletion of deoxycytidine kinase activity are cross-resistant to arabinosyl-5-azacytosine. Unlike cytosine arabinoside, arabinosyl-5-azacytosine does not readily undergo deamination. Schedule dependence has been demonstrated in mice bearing L1210 leukemia, with superior activity seen with multiple doses administered on each treatment day compared to administration of larger but less frequently administered doses. From preliminary data in solid tumor models, however, antitumor activity did not appear to be superior with continuous infusion compared to that observed on a bolus schedule. Preclinial toxicology studies indicated that the bone marrow and gastrointestinal tract were the main target organs. A single large dose of arabinosyl-5-azacytosine could be tolerated by both mice and dogs. When administered as a continuous infusion, the toxicity was related to both the dose and duration of exposure, suggesting that toxicity resulted from a critical time above a threshold concentration as opposed to the total area under the concentration-time curve. Phase I clinical trials have been initiated to determine the maximum tolerated dose on a low dose continuous infusion schedule for 72 hours and also on a high dose short infusion daily times five schedule.

Teniposide in the treatment of leukemia: a case study of conflicting priorities in the development of drugs for fatal diseases.

Teniposide, a semisynthetic epipodophyllotoxin, was found to be highly active against murine leukemias, and the combination of teniposide with cytosine arabinoside (ara-C) was curative in murine leukemia models. The antitumor activity in preclinical models prompted introduction of teniposide into the clinic in 1971. Although teniposide as a single agent rarely produced a complete remission in heavily pretreated leukemia patients, teniposide plus ara-C produced complete remissions in some patients with refractory and relapsed acute lymphoblastic leukemia (ALL). Innovative front-line and salvage regimens using teniposide have been developed that incorporate a multi-drug strategy with early intensification, rotation of drug combinations in maintenance, and regional therapy in an effort to improve the cure rate in leukemia. However, as the complexity of these regimens increases, the contribution of an individual component such as teniposide becomes less clear. Although some of these regimens for newly diagnosed and relapsed ALL are now thought to represent the best available therapy, teniposide remains an investigational agent. In this review, we outline and discuss the conflicts arising from the need to answer drug-specific issues, and, at the same time, facilitate the implementation of innovative, curative regimens.

N-methylformamide: cytotoxic, radiosensitizer, or chemosensitizer.

N-methylformamide (NMF), a polar solvent, is currently being evaluated by the National Cancer Institute (NCI) as an antineoplastic agent because of its activity against colon, mammary, and lung tumor xenografts. Results from preclinical studies suggest that it has radiosensitizing, chemosensitizing, and differentiating activity. Its mechanism of action remains unknown, but may involve cellular depletion of glutathione, cell membrane changes, or modulation of proto-oncogene expression. Preclinical toxicology studies conducted in mice, rats, and beagle dogs showed reversible hepatotoxicity to be dose-limiting. Clinically, NMF is administered both orally and by intravenous (IV) injection. The bioavailability with oral administration is 90% to 95%. The highest reported plasma concentration of NMF is approximately 4 mmol/L in a patient who received a dose of 2,000 mg/m2 of IV NMF. Biphasic elimination with IV NMF is seen on both the daily for five days and weekly for 3 weeks schedule. Approximately 5% to 7% of the total administered IV dose is excreted in the urine. In phase I studies, dose-limiting toxicities included reversible hepatotoxicity, a generalized malaise syndrome, and nausea and vomiting. One partial response has been reported in the 111 patients treated on phase II trials in colorectal, head and neck, and renal carcinomas. Suggestions for the future development of this drug are presented.