Tamoxifen modulation of cisplatin resistance in patients with metastatic melanoma. A biologically important observation

MiR-30a-5p confers cisplatin resistance by regulating IGF1R expression in melanoma cells

BACKGROUND

Melanoma is notoriously resistant to all current modalities of cancer therapies including chemotherapy. In recent years, microRNAs (miRNAs) have emerged as molecular regulators in the development and progression of melanoma. However, the relationship between microRNA and chemo-resistance of melanoma is little known. In present study, we aimed to investigate the miRNAs related to cisplatin-resistance in melanoma cells.

METHODS

After cisplatin (DDP) resistant melanoma cells (M8/DDP and SK-Mel-19/DDP) were established in-vitro, high-throughput screening of differentially expressed miRNAs between resistant cells and parental cells were performed.

RESULTS

It was found that a cancer-related miRNA, miR-30a-5p, was highly over-expressed in resistant cells. Transfection of miR-30a-5p mimic or inhibitor could alter the sensitivity of melanoma cells to cisplatin. Next, we showed that Insulin Like Growth Factor 1 Receptor (IGF1R) gene turned out to be a direct target of miR-30a-5p. Knockdown of IGF1R in melanoma cells could not only reduce the sensitivity to cisplatin but also lead to cell cycle arrest by regulating phosphorylation of Serine-Threonine Protein Kinase (P-AKT (Ser473)) and Tumor Protein P53 (P53).

CONCLUSION

Taken together, our study demonstrated that miR-30a-5p could influence chemo-resistance by targeting IGF1R gene in melanoma cells, which might provide a potential target for the therapy of chemo-resistant melanoma cells.

Estrogen signaling in lung cancer: an opportunity for novel therapy

Lung cancer is the leading cause of cancer death in U.S. and represents a major public health burden. Epidemiologic data have suggested that lung cancer in women may possess different biological characteristics compared to men, as evidenced by a higher proportion of never-smokers among women with lung cancer. Emerging data indicate that female hormones such as estrogen and progesterone play a significant role in lung carcinogenesis. It has been reported that estrogen and progesterone receptors are expressed in lung cancer cell lines as well as in patient-derived tumors. Hormone related risk factors such as hormone replacement therapy have been implicated in lung carcinogenesis and several preclinical studies show activity of anti-estrogen therapy in lung cancer. In this review, we summarize the emerging evidence for the role of reproductive hormones in lung cancer and implications for lung cancer therapy.

Tamoxifen vs. non-tamoxifen treatment for advanced melanoma: a meta-analysis

Although tamoxifen (TAM) is routinely used in advanced melanoma, it is still uncertain whether evidence exists to support this practice. This review assesses the benefits and harms of systemic therapy with TAM vs. without TAM on response and mortality in patients with advanced melanoma. MEDLINE, The Cochrane Database of Systemic Reviews, The Cochrane Central Register of Controlled Trials, EMBASE and LILACS were searched for randomized controlled trials comparing chemotherapy using and not using TAM in any dose, in patients of any age with advanced melanoma. References lists, databases of ongoing trials and conference proceedings were hand-searched. All included trials were evaluated for quality assessment. Primary outcomes were response and mortality. Secondary outcomes were hematologic and non hematologic toxicity, treatment-related mortality and quality of life. A meta-analysis was performed and results were presented as relative risk with 95% confidence interval. Nine randomized controlled trials met the inclusion criteria. Patients treated with TAM were more likely to respond, with a relative risk 1.36 (95% CI: 1.04-1.77, P = 0.02). However, there was no improvement in 1-year mortality. The incidence of hematologic toxicity was higher in the TAM group. Subgroup analyses showed that female patients were more likely to respond. Chemotherapies with TAM improve overall and partial response, but do not improve mortality in 1 year in advanced melanoma. Further use of TAM in melanoma should be done only in the context of clinical trials.

A Phase III Trial Evaluating the Combination of Cisplatin, Etoposide, and Radiation Therapy With or Without Tamoxifen in Patients With Limited-Stage Small Cell Lung Cancer

Based on both clinical and laboratory data that suggested that tamoxifen (TAM) enhanced the effectiveness of cisplatin (DDP)-based chemotherapy regimens, the Cancer and Leukemia Group B (CALGB) designed and initiated a prospective, randomized phase III trial to test the efficacy of the addition of high-dose TAM to a standard chemoradiation regimen of DDP and etoposide (VP-16) in patients with limited-stage small cell lung cancer (LS-SCLC). Between August 6, 1993, and January 15, 1999, 319 patients with LSSCLC were accrued to CALGB 9235. Patients were randomized to receive chemotherapy with or without high-dose TAM. Treatment on the non-TAM containing arm (arm 1) included DDP (80 mg/m2 intravenously day 1 only) and VP-16 (80 mg/m2 intravenously days 1-3) given every 3 weeks for a total of 5 cycles. Patients treated on arm 2 received the identical chemotherapy regimen as described here with the addition of high-dose TAM (80 mg orally twice per day), which was given for 5 days each cycle starting 1 day before the DDP. Thoracic radiation (XRT) given at 200 cGy 5 days per week to a total dose of 50 Gy began on day 1 of cycle 4 of chemotherapy and overlapped with cycle 5. Prophylactic cranial irradiation was offered to all patients who achieved a complete response or near-complete response. A total of 307 patients are evaluable for response. After the completion of the chemoradiation portion of the treatment, the overall response rate (ORR) was 88% for 154 patients treated without tamoxifen and 84% for 153 patients treated with tamoxifen with complete response (CR) rates of 49% and 50%, respectively. The median failure-free survivals of 12.3 months and 10.5 months and the overall survivals of 20.6 months and 18.4 months, respectively, were not statistically significant between the 2 arms. Toxicity was similar with and without tamoxifen. This phase III trial failed to demonstrate a positive effect on either the response or survival for the addition of TAM to standard etoposide-cisplatin-radiation management for patients with LS-SCLC. However, these data continue to support a positive effect of chemoradiation in the treatment of patients with LS-SCLC.

Adjuvant therapy for patients with high-risk malignant melanoma

The role of adjuvant therapy in the treatment of patients with high-risk malignant melanoma remains an area of intense investigation. The initial enthusiasm for high-dose interferon has been tempered by the results of more recent studies that allow for conflicting interpretations. Vaccine therapy trials have failed to clearly demonstrate a survival benefit, although several trials are currently ongoing. Recent studies of the role of chemotherapy suggest there may be combinations that have a survival benefit which deserve further study. This article will address patient selection and staging workup, and review options for treatment.

A combination of platinum and tamoxifen in advanced ovarian cancer failing platinum-based chemotherapy: results of a Phase II study

The treatment of recurrent or progressive ovarian cancer has limited therapeutic potential. The clinical outcome of second-line therapy largely depends on the potential chemo-sensitivity of the tumor expressed during up-front chemotherapy, as well as on the treatment-free interval from the last course of cytotoxic therapy. However, the identification of agents such as tamoxifen (TAM) at nontoxic doses, able to act synergistically with standard chemotherapy, may be useful to overcome resistance. Fifty patients with recurrent or progressive ovarian cancer following platinum (P)-based chemotherapy (28 platinum-resistant and 22 platinum-sensitive) entered a Phase II trial to evaluate the efficacy and toxicity of P re-challenge with the addition of TAM as a chemotherapy response modulator. The choice of the P compound (100 mg/m2 cisplatin or 400 mg/m2 carboplatin, q3 weeks) was made on the basis of the prior total cisplatin dose and the presence of neurotoxicity. TAM was administered at the doses of 80 mg/day for 30 days followed by 40 mg/day for the remaining period of treatment. Toxicity consisted mainly of mild to moderate nausea and vomiting (76%), peripheral neuropathy (43%), nephrotoxicity (4%), anemia (16%), leukopenia (58%) and thrombocytopenia (16%). The overall response to the P-TAM combination was 50% (complete response 30%; partial response 20%) with a median duration of 8.5 months (3-42). Sixty-four percent of the P-sensitive and 39% of the P-resistant patients responded (59% and 33%, respectively, for those bearing measurable disease). The overall median survival was 23 (3-48) and 19 months for the patients with measurable disease (20 months for the P-resistant group). This phase II trial confirmed the activity for a re-challenge employing a P compound and TAM in clinically defined P-resistant ovarian cancer patients. The mild toxicity profile and the relatively low cost of the treatment render further investigations on the P-TAM regimen worthwhile.

A phase II study of high dose tamoxifen and weekly cisplatin in patients with metastatic melanoma

We have previously demonstrated that the combination of tamoxifen and cisplatin has activity in patients with metastatic melanoma. In vitro studies have demonstrated that tamoxifen and cisplatin exhibit cytotoxic synergy in human melanoma cells and that this interaction is dependent on a tamoxifen effect. The mechanism of this effect is currently under investigation in in vitro studies. In an attempt to improve the complete response rate of this regimen, we initiated a phase II trial to determine the effect of the use of high dose tamoxifen and weekly cisplatin on the complete response rate, disease-free survival and overall survival. Tamoxifen was started on day 1 initially at a dose of 240 mg/day and continued until the patient was taken off treatment. This dose was subsequently lowered to 200 mg/day. Cisplatin (80 mg/m2) was begun on day 2 and repeated weekly for a total of 3 weeks. During week 4, the patient was not treated with cisplatin but was evaluated for response. If disease stabilization or regression was documented, the patient received a second 3 week cycle of cisplatin and was then re-evaluated for response. Patients with progressive disease at any evaluation were removed from the study. In 28 consecutive patients, the overall response rate was 32% (95% confidence interval 15.88-52.35%). One patient achieved a complete remission that lasted 22 months. All other responses were partial in nature. Toxicity was primarily nausea and vomiting. Two patients developed grade 2 renal toxicity. There were no episodes of deep venous thrombosis. This phase II study demonstrates that this combination has modest activity in patients with metastatic melanoma. However, this study failed to confirm our hypothesis that high dose tamoxifen would increase the complete response rate of this combination. While this combination has activity, the overall response rate is not significantly better that that observed with the original Dartmouth regimen and the toxicity is substantial. We do not recommend this dose and schedule for routine clinical use.

Phase II study of tamoxifen, ifosfamide, epirubicin and cisplatin combination chemotherapy in patients with non-small cell lung cancer failing previous chemotherapy

We conducted a phase II study of tamoxifen, ifosfamide, epirubicin, and cisplatin (TIEP) chemotherapy in patients with non-small cell lung cancer (NSCLC) who had failed previous chemotherapy, in order to assess the response and toxicity of TIEP. Between November 1997 and May 1999, 25 patients were treated. Twelve of the 25 patients (48%) had been previously treated with cisplatin-based combination chemotherapy. TIEP doses were tamoxifen 60 mg oral twice daily on days 1-3; ifosfamide 2.4 g/m(2) intravenous infusion (IV) 60 min with mesna on day 2; epirubicin 40 mg/m(2) IV bolus on day 2; and cisplatin 50 mg/m(2) IV 60 min on day 2 every 4 weeks for up to six cycles. Seventy one cycles were given to 25 patients, with a median of three cycles (range one to six cycles). All patients were evaluable for toxicity profile and response rate. As expected, the major toxicity was myelosuppression. Grade 3 or 4 neutropenia occurred in 15 patients (60%) during treatment, as well as in 31% of the total courses. Febrile neutropenia occurred in two patients. No toxic death occurred in this study. Grade 3 thrombocytopenia occurred in five patients with five cycles. Toxicities other than myelosuppression were few and mild in severity. After two cycles of treatment, five of 25 patients (20%) had a partial response (95% confidence interval 4.3-35.7%). Among 12 patients previously treated with cisplatin-based chemotherapy, three patients (25%) achieved a partial response. The median time to disease progression was 4.9 months and median survival was 7.7 months. The response rate and median survival were better than in our previous study of salvage chemotherapy with ifosfamide, 5-FU, and leucovorin; and with ifosfamide, epirubicin, 5-FU, and leucovorin. In conclusion, TIEP appears to be an active combination regimen with an acceptable toxicity profile in Chinese patients with NSCLC who have failed previous chemotherapy.

The effect of tamoxifen and cisplatin on the disease-free and overall survival of patients with high risk malignant melanoma

The adjuvant treatment of high-risk malignant melanoma remains problematic. Previously we reported moderate success in the treatment of metastatic disease using tamoxifen, cisplatin, dacarbazine and carmustine. Based upon data that suggested tamoxifen and cisplatin were the active agents in this regimen, we initiated a phase II trial of this combination in the adjuvant setting. We treated 153 patients with 4 cycles of tamoxifen (160 mg day(-1), days 1-7) and cisplatin (100 mg m(-2), day 2) for 28-day intervals. Patients received an anti-nausea regimen of dexamethasone with ondansetron or granisetron. During the first 2 years of follow-up, patients were evaluated every 2 months with a history, physical exam, laboratory work and computed tomography scans of the chest, abdomen and pelvis every 4 months. Thereafter, patients were evaluated every 3 months and radiographic studies were performed if necessary. Currently, with a median follow-up of 36 months, the disease-free survival (DFS) is 68.4% and overall survival (OS) is 84.5%. Kaplan-Meier analysis predicts a 5-year DFS of 62% with an OS of 79%. Relapses after 20 months have been rare. No effect of gender or number of positive lymph nodes was noted, however, stage of disease prior treatment was a factor. The major toxicity proved to be gastrointestinal in nature with nausea the most prevalent symptom. Minimal renal, haematologic and neurologic toxicity occurred. These preliminary results suggest that there is a positive impact of tamoxifen and cisplatin on both the DFS and OS of high-risk malignant melanoma patients. The 5-year projected DFS and OS compare favourably with those reported for the ECOG 1684 trial and warrant confirmation in a prospective randomized trial.

Phase II study of second-line therapy with DTIC, BCNU, cisplatin and tamoxifen (Dartmouth regimen) chemotherapy in patients with malignant melanoma previously treated with dacarbazine

This study assessed response rates to combination dacarbazine (DTIC), BCNU (carmustine), cisplatin and tamoxifen (DBPT) chemotherapy in patients with progressive metastatic melanoma previously treated with DTIC, as an evaluation of DBPT as a second-line regimen, and as an indirect comparison of DBPT with DTIC. Thirty-five consecutive patients received DBPT. The patients were divided into two groups. Group 1 comprised 17 patients with progressive disease (PD) on DTIC + tamoxifen therapy who were switched directly to DBPT. Group 2 comprised 18 patients not immediately switched to DBPT and included patients who had either a partial response (PR; one patient) or developed stable disease (SD; four patients) with DTIC, or received adjuvant DTIC (nine patients). All except four patients had received tamoxifen at the time of initial DTIC treatment. Median times since stopping DTIC were 22 days (range 20-41) and 285 days (range 50-1,240) in Groups 1 and 2 respectively. In Group 1, one patient developed SD for 5 months and the remainder had PD. In Group 2, there were two PRs, four patients with SD (4, 5, 6, and 6 months), and 11 with PD. These results indicate that the DBPT regimen is not of value in melanoma primarily refractory to DTIC. There were responses in patients not directly switched from DTIC to DBPT, suggesting combination therapy may be of value in a small subgroup of melanoma patients.

Dacarbazine, nimustine hydrochloride, cisplatin and tamoxifen combination chemotherapy for advanced malignant melanoma

Melanoma is an uncommon disease in Japan. The incidence, however, has been gradually increasing in the last two decades, as in many other countries worldwide. Ten patients with metastatic malignant melanoma were treated between March of 1997 and April of 1998 in the Department of Dermatology, National Cancer Center Hospital, with a combination chemotherapy consisting of dacarbazine (DTIC), nimustine hydrochloride (ACNU), cisplatin (CDDP), and tamoxifen (TAM). The patients characteristics were as follows: four were males and six females; the age range was 33-70 years; all were Japanese; sites of primary disease: extremities 4, primary unknown 3, nasal cavity 1, anus 1, scalp 1; sites of metastases: lymph nodes 6, pulmonary system 5, skin 2, liver 3, gall bladder 1, adrenal gland 1. The chemotherapy regimen included DTIC 220 mg/m2/i.v. on days 1 through 3, ACNU 60 mg/m2/i.v. on day 1, cisplatin 25 mg/m2/i.v. on days 1 through 3, and tamoxifen 10 mg p.o. twice daily. One patient achieved a complete response and 3 showed partial responses. The response rate was 40%. The four responders included those with metastases to the nodes, lung, and liver. The main toxicities were nausea, vomiting, leucopenia, anemia, and thrombocytopenia. This regimen is a fairly effective combination against metastatic melanoma.

Primary malignant melanoma of the esophagus: report of a case successfully treated with pre- and post-operative adjuvant hormone-chemotherapy

Primary malignant melanoma of the esophagus is a very rare and deadly disease, with a survival of 2.2% at 5 years and a median survival of about 10 months. The aggressive biological behavior of this disease and advanced stage at the time of diagnosis together with the lack of effective treatment have contributed to its poor prognosis. We present the case of a 45-year-old Japanese man diagnosed as having a primary melanoma of the esophagus by clinical evaluation and a histological examination of endoscopic biopsy specimens. A novel approach consisting of pre- and post-operative chemo-hormone therapy with dacarbazine, nimustine, cisplatin and tamoxifen in conjunction with radical esophagectomy accompanied by lymph node dissection was carried out. The tumor size was decreased to 70% by the pre-operative chemo-hormone therapy. During the post-operative 32 months of follow-up, no evidence of recurrence or metastatic disease has been found. Although this is only one case, the outcome observed suggests that the combination of pre- and post-operative chemo-hormone therapy and radical esophagectomy with lymph node dissection is a modality that can increase the possibility of curability or at least improve the survival of patients with primary melanoma of the esophagus.

The evidence for tamoxifen and chemotherapy as treatment for metastatic melanoma

Tamoxifen, an oestrogen antagonist routinely used in the treatment of breast cancer, has been used in clinical trials for patients with melanoma since the late 1970s. Following initial promise as a single agent for the treatment of metastatic melanoma, tamoxifen was first combined with chemotherapy in this setting in 1984. Since then, numerous phase II studies have combined tamoxifen with different chemotherapeutic agents, with some suggesting that tamoxifen significantly improves the efficacy of cisplatin-containing regimens. Overall response rates range from 8 to 60%. Several randomised trials also have been completed, with response rates of 12-30%. One such study showed statistically significant improvements in response rate and survival when tamoxifen was added to dacarbazine; however, other studies have not observed these benefits with the addition of tamoxifen to cisplatin-containing regimens. At present, the author's opinion is that the strength of evidence does not support the use of tamoxifen in combination with cisplatin-containing chemotherapy for the treatment of metastatic melanoma. Controversy remains as to whether the strength of evidence from the randomised trials outweighs the combined evidence from numerous nonrandomised trials. Resolution of this controversy may depend on the results of the North Central Cancer Therapy Group and/or a common agreement as to relative strength of evidence from clinical trials of different designs.

Systemic therapy in melanoma

The patient with surgically incurable melanoma presents a difficult problem for the medical oncologist. Single chemotherapeutic agents at conventional doses produce bona fide but infrequent remissions. The most active single agent for the treatment of metastatic melanoma is dacarbazine (DTIC). Until recently, combinations of drugs yielded no real improvement over treatment with the individual components. The combination of DTIC + carmustine (BCNU) + cisplatin + tamoxifen (the "Dartmouth regimen") appears to be more effective than DTIC alone, but prospective randomized trials comparing the two are still in progress. The contribution of tamoxifen to the observed results continues to be evaluated. Biological agents, such as interferon and interleukin-2, have lower overall response rates compared to chemotherapy regimens, but response duration appears to be longer. Chemotherapy combined with biotherapy offers the promise of higher response rates and long-term durable remissions. The results from high-dose regimens that use autologous bone marrow or peripheral stem cell support have not been sufficient to justify the added toxicity. Although advanced melanoma often is not curable with systemic therapy, the considered use of currently available regimens can induce clinically significant remissions and, possibly, prolong life in some patients.

A phase I and pharmacokinetic study of high dose tamoxifen and weekly cisplatin in patients with metastatic melanoma

BACKGROUND

The authors have previously demonstrated that tamoxifen (TAM) is synergistic with cisplatin (DDP) in patients with metastatic melanoma. In vitro studies have demonstrated that TAM/DDP synergy is dependent on a TAM effect that is currently under investigation. In an attempt to improve the complete response rate of this regimen, the authors initiated a Phase I trial to determine the maximum tolerated dose (MTD) of TAM that could be safely administered with weekly DDP.

METHODS

TAM was started on Day 1 at a dose of 80 mg/day and was increased by 40 mg to the MTD in groups of 3 patients. DDP (80 mg/m2) was begun on Day 2 and repeated weekly for a total of 3 weeks. During Week 4, the patients were not treated with DDP but instead evaluated for response. If disease stabilization or regression was documented, the patients received a second 3-week cycle of DDP and were then reevaluated for response. Patients with progressive disease were removed from the study.

RESULTS

In 25 consecutive patients, the overall response rate was 20%. No responses were observed in patients treated with TAM at a dose of <240 mg/day. Among 13 patients treated at or above this dose, there were 2 complete responses, 3 partial responses, 2 mixed responses, and 6 patients with progressive disease. The overall response rate for patients treated with 240 mg of TAM or higher was 38.5%. Dose-limiting toxicity, which occurred at a TAM dose of 280 mg/day, was primarily hematologic and gastrointestinal in nature. There was one toxic death (due to septic neutropenia) at this dose. There were no episodes of thrombosis.

CONCLUSIONS

A TAM dose of 240 mg/day is the recommended Phase II dose. Based on the 38.5% overall response rate at this dose, the authors have initiated a Phase II study.

Synergistic interaction between cisplatin and tamoxifen delays the emergence of cisplatin resistance in head and neck cancer cell lines

The interaction between cisplatin (cDDP) and tamoxifen (TAM) was evaluated in the human head and neck squamous-carcinoma cell lines UM-SCC-10B and UM-SCC-5. Synergy between cDDP and TAM was demonstrated in the UM-SCC-10B cell line. Concordant with the synergistic effect between cDDP and TAM, the rate of development of resistance to cDDP was delayed when selections were performed in the presence of TAM. However, in the UM-SCC-5 cell line, TAM was neither synergistic nor did it delay the development of cDDP resistance. The difference with respect to the synergistic interaction of cDDP with TAM and the effect on the development of cDDP resistance in the UM-SCC-10B and UM-SCC-5 cell lines was not related to any significant difference in the accumulation of the cDDP analog [3H]-cis-dichloro(ethylenediamine)platinum(II) (DEP), drug sensitivity [concentrations inhibiting colony formation by 50% (IC50 values) were 6.5 and 7.2 microM for cDDP and 3.5 and 3.2 microM for TAM, respectively], the number of estrogen and progesterone receptors (negative in both cell lines), the number of antiestrogen binding sites (404 +/- 85 and 353 +/- 24 fmol/mg protein, respectively), or the affinity of TAM for these binding sites (1.7 and 1.5 nM, respectively). Importantly, however, we demonstrated that TAM can delay the emergence of resistance to cDDP in head and neck carcinomas and that this effect is linked to the nature of the interaction between cDDP and TAM.

Tamoxifen delays the development of resistance to cisplatin in human melanoma and ovarian cancer cell lines

The development of resistance to cisplatin (DDP) occurs rapidly both in vitro and in vivo, and constitutes a major obstacle to effective therapy. We have previously demonstrated that there is a highly synergistic interaction between tamoxifen (TAM) and DDP against cell lines representative of three different human cancers: melanoma, ovarian carcinoma and small-cell lung cancer. The purpose of these studies was to determine if TAM interferes with the development of resistance to DDP. T-289 melanoma cells and 2008 ovarian cancer cells were cultured with increasing concentrations of DDP +/- TAM in an attempt to induce resistance to DDP. At various time points the cells were removed from culture and the degree of resistance to DDP was quantitated. Concurrent exposure to TAM and DDP decreased both the rate and the absolute magnitude of resistance to DDP in both melanoma and ovarian cancer cell lines. In the T-289 cell line the rate was decreased by a factor of 3.4 +/- 1.4 (P < 0.05), while in the 2008 cell line the rate was decreased by a factor of 2.4 (P < 0.01). TAM decreases the rate as well as the absolute magnitude of in vitro resistance to DDP in both melanoma and ovarian cancer cell lines. These data suggest that the concurrent administration of TAM and DDP may result in a delay in the development of resistance to DDP which may have important clinical implications in the design of DDP-containing regimens.

Tamoxifen modulation of cisplatin cytotoxicity in human malignancies

Recent clinical trials have indicated that addition of tamoxifen (TAM) to a combination of cisplatin (DDP), carmustine and dacarbazine markedly increases the overall objective response rate of patients with metastatic malignant melanoma. Previous studies have determined that there is remarkable synergy between TAM and DDP in a human melanoma cell line T-289. Using the technique of median effect analysis, in clonogenic assay, we observed a highly synergistic interaction between TAM and DDP. To determine whether or not this synergistic interaction was unique to human melanomas, or is generally observed in other types of malignancy, we examined the nature of this interaction using a human ovarian carcinoma and small cell lung cancer cell line. Synergy was observed in both cell lines. In the case of all 3 types of malignancy, synergy was observed at concentrations of both TAM and DDP that can be achieved in patients. Our results demonstrate that cytotoxic synergy between the DDP and TAM is observed in cell lines established from multiple types of human malignancies. It is important to note that the synergy between TAM and DDP is not dependent on the presence of estrogen or progesterone receptors. Since TAM is well tolerated by patients, it is particularly attractive as a potential agent with which to sensitize human tumors to DDP.