Clinical trials of combination therapies for HIV infection. Rationale for development of multidrug therapy.
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Biomedical subjects
Publications and source records attributed to D Hoth.
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Through a compassionate plea program (Treatment Investigational New Drug), 4805 patients with acquired immunodeficiency syndrome who previously had experienced Pneumocystis carinii pneumonia (PCP) received zidovudine (Retrovir, formerly azidothymidine). Overall survival at 44 weeks after initiation of therapy was 73% (+/- 2.1%). A positive association was found between survival and pretherapy clinical status as defined by hemoglobin level, functional ability, and stage of disease as measured by time since diagnosis of PCP. For patients with baseline hemoglobin levels of 120 g/L or greater, Karnofsky scores of 90 or greater, and PCP diagnosis within 90 days prior to initiation of therapy, 44-week survival was 88%. Adverse clinical experiences associated with zidovudine therapy were consistent with those from a double-blind, placebo-controlled trial. Survival experience of this large and diverse cohort is consistent with, and extends data from, this clinical trial. Comparison with available natural history data suggests that zidovudine therapy is associated with increased 44-week survival of post-PCP patients with acquired immunodeficiency syndrome.
We examined the activity reported in phase II trials for all cytotoxic drugs introduced into clinical trial by the National Cancer Institute (NCI) since 1970. For each drug in each tested tumor type we derived a response rate from the pooled data of all trials reported either in the literature or to the NCI. We rated a drug active if the lower 80% confidence bound of the response rate was greater than 10%. Of the 83 drugs developed and introduced by the NCI, there are 47 which we considered evaluable. Of these drugs, 24 were rated active in at least one cancer type, of which ten were analogs of drugs in wide clinical use. Diseases most commonly responsive include lymphoma (74% of the tested drugs rated active), leukemia (35%), urothelial cancer (29%), small cell lung cancer (29%), ovarian cancer (22%), cervical cancer (22%), and breast cancer (18%). For colon cancer and melanoma, only one of 42 and two of 30 tested drugs rated active, respectively. We also examined the completeness of clinical testing: among the 47 drugs there were 20 tested in greater than or equal to 14 patients with leukemia, 23 tested in patients with lymphoma, and 18 tested in patients with small cell lung cancer; whereas 34 drugs for breast cancer, 42 for colon cancer, and 33 for non-small cell lung cancer were more completely evaluated. Considering the "clinical panel" of seven cancer types (breast, non-small cell lung, small cell lung, colon, melanoma, leukemia, and lymphoma), drugs were tested in greater than or equal to 30 patients in a median of four tumor types. Testing in this panel failed to detect activity in only one drug found active in another tumor, although testing in diseases other than this clinical panel was even less complete. Phase II testing should emphasize completion of minimum accrual goals, testing in patient populations with minimum prior therapy, and evaluation in a minimum set of tumor types.
A new class of marine compounds, the didemnins, with potent antitumor activity has been identified. They share the novel structure of a cyclic depsipeptide. Among three structurally related compounds, didemnin B is by far the most potent in its in vitro cytotoxicity and in vivo antitumor activity (0.001 microgram/ml inhibits the growth of L1210 leukemia cells by 50%). It also demonstrates good antitumor activity against B16 melanoma and moderate activity against M5076 sarcoma and P388 leukemia. The compound also has good antiviral and potent immunosuppressive properties. Although the precise mechanism of action for the cytotoxicity remains unknown, the agent inhibits protein synthesis more than DNA synthesis and the inhibition of protein synthesis is closely correlated with inhibition of L1210 cell growth. Toxicology studies in CD2F1 mice, Fischer 344 rats and beagle dogs reveal that major target organs are the lymphatics, gastrointestinal tract, liver and kidney. Phase I trials are currently in progress under the auspices of the National Cancer Institute.
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.
Ninety patients with breast cancer refractory to cyclophosphamide/fluorouracil/methotrexate (CMF) have been randomized in their treatment, receiving either doxorubicin or mitoxantrone. Seventy-nine have received two full courses of therapy. Twelve of the 40 (30%) who initially received doxorubicin responded, whereas eight of the 47 (17%) who received mitoxantrone responded. These rates are not statistically different. The degree of myelosuppression was equivalent. Patients who received mitoxantrone had less nausea, vomiting, alopecia, and fatigue. Controllable clinical congestive heart failure developed in seven patients, and four others had a deterioration of noninvasive measures of cardiac function without clinical failure. One patient with clinical heart failure developing received only doxorubicin and one, only mitoxantrone, whereas the others received both agents. The duration of remission and time lapsed before disease progression were almost identical for the two regimens. This study included a crossover design. Two of 22 (10%) patients receiving doxorubicin and five of 24 (21%) receiving mitoxantrone as secondary therapy responded. This suggests that there is not absolute cross-resistance between these agents. We conclude that the efficacy of these two drugs is comparable in patients refractory to CMF, though the nonhematologic side effects of mitoxantrone are less.
The s-triazine derivatives have shown preclinical antitumor activity against several histologic types. The most widely used compound of this class in the clinic, hexamethylmelamine, has been largely restricted to oral use because of its low solubility and lack of stability in solutions suitable for parenteral administration. New analogs were sought which were soluble and stable and retained antitumor activity. Pentamethylmelamine (PMM), the monodemethylated derivative, showed these promising characteristics. Preclinical toxicology studies of PMM in mice, dogs, and monkeys showed toxic manifestations that involved the hematopoietic, lymphatic, renal, male reproductive, gastrointestinal, and nervous systems; these changes were both infusion-rate- and dose-dependent. Clinical phase I trials of PMM were performed using a variety of infusion durations and frequency schedules. The dose-limiting toxic effect common to all of these trials was protracted nausea and vomiting. In addition, some studies reported dose-limiting central nervous system manifestations in the form of agitation, drowsiness, somnolence, and even coma. Mild to moderate hematologic changes were noted. Because of the severity and frequency of the gastrointestinal and central nervous system toxic effects observed in the completed trials, no new clinical trials of PMM sponsored by the National Cancer Institute are planned. However, the interest in finding a clinically useful parenteral triazine continues.
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We analyzed the therapeutic effect reported in 187 phase I trials of 54 anticancer drugs introduced into National Cancer Institute-sponsored clinical trial from 1974 to 1982. An additional 12 drugs entering clinical trial prior to 1974 were also examined. Objective responses (partial and complete) were reported in 271 of the 6447 patients (4.2%). Thirty-nine percent of the patients were treated at an initial dose level greater than or equal to the dose ultimately recommended for phase II trials. Patients in phase I trials generally had adequate performance status (Karnofsky scale greater than 80% or Eastern Cooperative Oncology Group 0, 1, or 2). More than 90% of the patients had received prior chemotherapy. We next examined the therapeutic effect observed in phase II trials for each of the drugs. Thirty-eight of the 54 drugs had completed at least one phase II trial. Twenty-one drugs were rated active, and nine were rated inactive. For the drugs entering clinical trial since 1974, the median phase I response rate for those active in phase II was 4.3%, compared to 2.7% for the drugs not found active in phase II. This difference was not statistically significant. The tabulated response rate in phase I trials reported here should be interpreted cautiously. There are many factors which may contribute to significant variability in the reported response rates, including the heterogeneity of patient population with respect to prior therapy and tumor type, lack of requirement for measurable/evaluable disease on entry into many studies, and variations in the rigor with which tumor sites are followed for response. These factors may lead to either an overestimate or underestimate of the true response rate in phase I. Although little therapeutic effect is produced in phase I, we discuss several measures which might increase patient benefit during these trials.
Gallium nitrate is the anhydrate salt of the naturally occurring heavy metal. It has demonstrated antitumor activity in a variety of murine tumor models, including Walker carcinosarcoma 256, fibrosarcoma M-89, leukemia K-1964, adenocarcinoma 755, mammary carcinoma YMC, reticulum cell sarcoma A-RCS, lymphoma P1798, and osteosarcoma 124F. Preclinical studies performed in rats, rabbits, dogs, and monkeys showed the dose-limiting toxicity to be renal. The hepatic, pulmonary, gastrointestinal, hematologic, and integumentary systems were also involved. The major route of elimination is the kidneys, with 35%-71% of the infused dose excreted within 24 hours. Three phase I studies suggested the following phase II doses: 700-750 mg/m2 by short infusion, once every 2-3 weeks; 300 mg/m2/day by short infusion for 3 consecutive days, to be repeated every 2 weeks; and 300 mg/m2/day by continuous infusion for 7 consecutive days, to be repeated every 3-5 weeks. The major organ toxicity reported was renal; however, this can be adequately controlled either by hydration and osmotic diuresis or by use of continuous schedule. (Either maneuver appears to allow delivery of the recommended phase II dose with a less than 30% risk of change in serum creatinine.) In limited phase II evaluation, the drug has shown antitumor activity in patients with either refractory lymphomas or small cell lung carcinoma, with total objective response rates of 28% and 11%, respectively. In addition, it has been effective in the treatment of patients with cancer-related hypercalcemia by having an inhibitory effect on calcium reabsorption from bone. Single-agent phase II studies are planned in all major tumor types. Some are already ongoing in patients with genitourinary malignancies (renal, bladder, prostate, testicular), small cell lung carcinoma, and multiple myeloma. Metabolic studies are in progress at Memorial Sloan-Kettering Cancer Center to further elucidate the mechanism or mechanisms of the hypocalcemic effects.
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.
Mayo clinic and georgetown university carried out a cooperative phase II study of chlorozotocin in measurable advanced large bowel carcinoma. Of 78 evaluable patients randomized, 39 received low-dose (120 mg/m2 if previously untreated, 100 mg/m2 if previously treated) and 39 high-dose (200 mg/m2 if previously untreated, 175 mg/m2 if previously treated) chlorozotocin intravenously at 6-week intervals. Both groups were comparable in regard to age, prior treatment, treating institution, site of metastases, and performance scores. Overall response rate was 8%, including 5% in low-dose patients and 10% in high-dose patients. Toxicity was mild to moderate, with gastrointestinal toxicity substantially, and hematologic toxicity somewhat less, than seen with other nitrosoureas. Time to progression and survival showed no significant difference between patients treated on the low- and high-dose schedules. As chlorozotocin produced less nausea and vomiting than other nitrosoureas, even in the high-dose regimen, it should be considered for evaluation in neoplasms where nitrosoureas have shown more activity than in colorectal carcinoma.
Chlorozotocin is a glucose-substituted chloroethyl nitrosourea with pharmacologic properties suggesting it is a relatively nonmyelosuppressive cancer chemotherapy drug. Preclinical studies have shown that this drug possesses approximately twice the in vitro alkylating activity of the chloroethyl nitrosoureas BCNU and CCNU. In the L1210 leukemia system, chlorozotocin has curative activity at doses that result in minimal bone marrow toxicity. In vitro studies of human bond marrow stem cells have shown that chlorozotocin is relatively sparing of these cells compared to BCNU. Phase I and phase II trials in man have been performed that show that chlorozotocin's dose-limiting toxicity is thrombocytopenia at doses greater than 120 mg/m2. In the phase II trial, 16% of patients with colon cancer and 20% of patients with malignant melanoma evidenced objective regression of disease. Chlorozotocin is now undergoing phase II evaluation in combination chemotherapy trials in colon and stomach 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.
Thirty-six patients with advanced measurable gastric cancer were treated with a new combination chemotherapy program consisting of 5-fluorouracil, Adriamycin and mitomycin-C (FAM). Fifty percent of patients achieved an objective partial response. The median duration of remission was 9.5 months and the median survival for responding patients was 13.5 months, with 2 remaining alive at 14 and 26 months. The median survival for nonresponding patients was 3.0 months and all were dead by 6 months after initiation of therapy. The median survival of all 36 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, and produced only moderate bone marrow suppression. These results demonstrate that some patients with advanced gastric cancer can be effectively palliated with FAM chemotherapy. Phase III trials are warranted to assess the effect of the FAM regimen on the survival of patients with advanced gastric cancer.
Seventy-eight advanced breast cancer patients, most of whom had had prior treatment, were treated with the synthetic antiestogen tamoxifen. The overall objective response rate was 27% (21/78). An additional 19% (15/78) showed disease stabilization. Sixty-seven percent (14/21) of the responses were in soft tissue sites, 24% (5/21) on bony sites and one each occurred in liver and nodular lung disease. Forty percent of patients with soft-tissue disease alone responded, while less than 10% of patients with visceral disease showed responses in visceral sites. The response rate was 28% among patients with a known positive estrogen receptor (ER) assay. It was 21% among patients who had previously received cytotoxic drugs. Toxicity was mild and was seen in nausea and vomiting, hot flushes and vaginal bleeding, and occasional myelosuppression. One patient was withdrawn from the study because of a rash. In two patients the disease flared, once with concomitant hypercalcemia. Tamoxifen is a useful agent for advanced breast cancer even in some patients with visceral disease.