Pre-operative ctDNA predicts survival in high-risk stage III cutaneous melanoma patients.

BACKGROUND: The outcomes of patients with stage III cutaneous melanoma who undergo complete surgical resection can be highly variable, and estimation of individual risk of disease recurrence and mortality remains imprecise. With recent demonstrations of effective adjuvant targeted and immune checkpoint inhibitor therapy, more precise stratification of patients for costly and potentially toxic adjuvant therapy is needed. We report the utility of pre-operative circulating tumour DNA (ctDNA) in patients with high-risk stage III melanoma. PATIENTS AND METHODS: ctDNA was analysed in blood specimens that were collected pre-operatively from 174 patients with stage III melanoma undergoing complete lymph node (LN) dissection. Cox regression analyses were used to evaluate the prognostic significance of ctDNA for distant metastasis recurrence-free survival and melanoma-specific survival (MSS). RESULTS: The detection of ctDNA in the discovery and validation cohort was 34% and 33%, respectively, and was associated with larger nodal melanoma deposit, higher number of melanoma involved LNs, more advanced stage and high lactate dehydrogenase (LDH) levels. Detectable ctDNA was significantly associated with worse MSS in the discovery [hazard ratio (HR) 2.11 P < 0.01] and validation cohort (HR 2.29, P = 0.04) and remained significant in a multivariable analysis (HR 1.85, P = 0.04). ctDNA further sub-stratified patients with AJCC stage III substage, with increasing significance observed in more advanced stage melanoma. CONCLUSION: Pre-operative ctDNA predicts MSS in high-risk stage III melanoma patients undergoing complete LN dissection, independent of stage III substage. This biomarker may have an important role in determining prognosis and stratifying patients for adjuvant treatment.

Five-year survival outcomes for patients with advanced melanoma treated with pembrolizumab in KEYNOTE-001.

BACKGROUND: Pembrolizumab demonstrated robust antitumor activity and safety in the phase Ib KEYNOTE-001 study (NCT01295827) of advanced melanoma. Five-year outcomes in all patients and treatment-naive patients are reported herein. Patients whose disease progressed following initial response and who received a second course of pembrolizumab were also analyzed. PATIENTS AND METHODS: Patients aged ≥18 years with previously treated or treatment-naive advanced/metastatic melanoma received pembrolizumab 2 mg/kg every 3 weeks, 10 mg/kg every 3 weeks, or 10 mg/kg every 2 weeks until disease progression, intolerable toxicity, or patient/investigator decision to withdraw. Kaplan-Meier estimates of overall survival (OS) and progression-free survival (PFS) were calculated. Objective response rate and PFS were based on immune-related response criteria by investigator assessment (data cut-off, September 1, 2017). RESULTS: KEYNOTE-001 enrolled 655 patients with melanoma; median follow-up was 55 months. Estimated 5-year OS was 34% in all patients and 41% in treatment-naive patients; median OS was 23.8 months (95% CI, 20.2-30.4) and 38.6 months (95% CI, 27.2-not reached), respectively. Estimated 5-year PFS rates were 21% in all patients and 29% in treatment-naive patients; median PFS was 8.3 months (95% CI, 5.8-11.1) and 16.9 months (95% CI, 9.3-35.5), respectively. Median response duration was not reached; 73% of all responses and 82% of treatment-naive responses were ongoing at data cut-off; the longest response was ongoing at 66 months. Four patients [all with prior response of complete response (CR)] whose disease progressed during observation subsequently received second-course pembrolizumab. One patient each achieved CR and partial response (after data cut-off). Treatment-related AEs (TRAEs) occurred in 86% of patients and resulted in study discontinuation in 7.8%; 17% experienced grade 3/4 TRAE. CONCLUSIONS: This 5-year analysis of KEYNOTE-001 represents the longest follow-up for pembrolizumab to date and confirms the durable antitumor activity and tolerability of pembrolizumab in advanced melanoma. CLINICAL TRIAL REGISTRY: ClinicalTrials.gov, NCT01295827.

Associations of pigmentary and naevus phenotype with melanoma risk in two populations with comparable ancestry but contrasting levels of ambient sun exposure.

BACKGROUND: People at high risk of developing melanoma are usually identified by pigmentary and naevus phenotypes. OBJECTIVE: We examined whether associations of these phenotypes with melanoma risk differed by ambient sun exposure or participant characteristics in two population-based, case-control studies with comparable ancestry but different ambient sun exposure. METHODS: Data were analysed from 616 cases and 496 controls from the Australian Melanoma Family Study and 2012 cases and 504 controls from the Leeds (UK) case-control study. Questionnaire, interview and dermatological skin examination data were collected using the same measurement protocols. Relative risks were estimated as odds ratios using unconditional logistic regression, adjusted for potential confounders. RESULTS: Hair and skin colour were the strongest pigmentary phenotype risk factors. All associations of pigmentary phenotype with melanoma risk were similar across countries. The median number of clinically assessed naevi was approximately three times higher in Australia than Leeds, but the relative risks for melanoma associated with each additional common or dysplastic naevus were higher for Leeds than Australia, especially for naevi on the upper and lower limbs. Higher naevus counts on the head and neck were associated with a stronger relative risk for melanoma for women than men. The two countries had similar relative risks for melanoma based on self-reported naevus density categories, but personal perceptions of naevus number differed by country. There was no consistent evidence of interactions between phenotypes on risk. CONCLUSIONS: Classifying people at high risk of melanoma based on their number of naevi should ideally take into account their country of residence, type of counts (clinical or self-reported), body site on which the naevus counts are measured and sex. The presence of naevi may be a stronger indicator of a genetic predisposition in the UK than in Australia based on less opportunity for sun exposure to influence naevus development.

Circulating tumour DNA predicts response to anti-PD1 antibodies in metastatic melanoma.

BACKGROUND: Programmed death 1 (PD1) inhibitors are now a foundation of medical management of metastatic melanoma. This study sought to determine whether circulating tumour DNA (ctDNA) provides useful early response and prognostic information. PATIENTS AND METHODS: We evaluated the relationship between pre-treatment and early on treatment ctDNA and outcome in melanoma patients treated with PD1 inhibitors alone or in combination with ipilimumab. RESULTS: ctDNA was detected in 40/76 patients (53%) at baseline, and correlated with stage, LDH levels, disease volume and ECOG performance. RECIST response was 72% (26/36) in group A (undetectable ctDNA at baseline), 77% (17/22) in group B (elevated ctDNA at baseline but undetectable within 12 weeks of therapy) and 6% (1/18) in group C (elevated ctDNA at baseline and remained elevated during treatment). The median PFS was not reached in groups A and B and was 2.7 months for group C [hazard ratio (HR) 0.09; P < 0.001 for group A versus C, and 0.16; P < 0.001 for group B versus C]. The median OS was not reached for groups A and B and was 9.2 months for group C (HR 0.02; P < 0.001 for group A versus C and 0.14; P < 0.001 for group B versus C). The poor outcome measures associated with group C remained significant in multivariate analysis adjusted for LDH, performance status, tumour stage and disease volume. The predictive value for ctDNA for response was confirmed in a separate validation cohort (n = 29, P < 0.01). CONCLUSION: Longitudinal assessment of ctDNA in metastatic melanoma patients receiving treatment with PD1 inhibitors is an accurate predictor of tumour response, PFS and OS. Patients who had a persistently elevated ctDNA on therapy had a poor prognosis, and this may guide combination and sequencing of subsequent therapies.

Vemurafenib in metastatic melanoma patients with brain metastases: an open-label, single-arm, phase 2, multicentre study.

Background: Vemurafenib has shown activity in patients with BRAFV600 mutated melanoma with brain metastases (BM). This phase 2 study evaluated vemurafenib in patients with/without prior treatment for BM. Methods: Patients with BRAFV600 mutated melanoma with BM were enrolled into cohort 1 (previously untreated BM) and cohort 2 (previously treated BM) and received vemurafenib (960 mg BID) until disease progression (PD) or intolerance. Primary endpoint was best overall response rate (BORR) in the brain in cohort 1 that was evaluated using modified RECIST 1.1 criteria using lesions ≥0.5 cm to assess response. Results: 146 patients were treated (cohort 1 n = 90; cohort 2 n = 56), 62% of whom were male. Median (range) time since diagnosis of BM: 1.0 (0-9) month in cohort 1 and 4.2 (1-68) months in cohort 2. Median duration of treatment was 4.1 months (range 0.3-34.5) in cohort 1 and 4.1 months (range 0.2-27.6) in cohort 2. Intracranial BORR in cohort 1 by an independent review committee (IRC) was 18% (2 CRs, 14 PRs). Extracranial BORR by IRC was 33% in cohort 1 and 23% in cohort 2. Median PFS (brain only, investigator-assessed) was 3.7 months (range 0.03-33.4; IQR 1.9-5.6) in cohort 1 and 4.0 months (range 0.3-27.4; IQR 2.2-7.4) in cohort 2. Median OS was 8.9 months (range 0.6-34.5; IQR 4.9-17.0) in cohort 1 and 9.6 months (range 0.7-34.3; IQR 4.5-18.4) in cohort 2. Adverse events (AEs) were similar in type, grade and frequency to other studies of single-agent vemurafenib. Grade 3/4 AEs occurred in 59 (66%) patients in cohort 1 and 36 (64%) in cohort 2. Overall, 84% of patients died during the study (86% in cohort 1 and 80% in cohort 2), mainly due to disease progression. Conclusions: The study demonstrates clinically meaningful response rates of melanoma BM to vemurafenib, which was well tolerated and without significant CNS toxicity.

Characteristics of pyrexia in BRAFV600E/K metastatic melanoma patients treated with combined dabrafenib and trametinib in a phase I/II clinical trial.

BACKGROUND: Pyrexia is a frequent adverse event with combined dabrafenib and trametinib therapy (CombiDT), but little is known of its clinical associations, etiology, or appropriate management. PATIENTS AND METHODS: All patients on the BRF133220 phase I/II trial of CombiDT treated at the standard dose (150/2) were included for assessment of pyrexia (n = 201). BRAF and MEK inhibitor-naïve patients (n = 117) were included for efficacy analyses. Pyrexia was defined as temperature ≥38°C (≥100.4(°)F) or related symptoms. RESULTS: Fifty-nine percent of patients developed pyrexia during treatment, 24% of which had pyrexia symptoms without a recorded elevation in body temperature. Pyrexia was grade 2+ in 60% of pyrexia patients. Median time to onset of first pyrexia was 19 days, with a median duration of 9 days. Pyrexia patients had a median of two pyrexia events, but 21% had three or more events. Various pyrexia management approaches were conducted in this study. A trend was observed between dabrafenib and hydroxy-dabrafenib exposure and pyrexia. No baseline clinical characteristics predicted pyrexia, and pyrexia was not statistically significantly associated with treatment outcome. CONCLUSIONS: Pyrexia is a frequent and recurrent toxicity with CombiDT treatment. No baseline features predict pyrexia, and it is not associated with clinical outcome. Dabrafenib and metabolite exposure may contribute to the etiology of pyrexia. The optimal secondary prophylaxis for pyrexia is best studied in a prospective trial.

A randomized, controlled phase III trial of nab-Paclitaxel versus dacarbazine in chemotherapy-naïve patients with metastatic melanoma.

BACKGROUND: The efficacy and safety of nab-paclitaxel versus dacarbazine in patients with metastatic melanoma was evaluated in a phase III randomized, controlled trial. PATIENTS AND METHODS: Chemotherapy-naïve patients with stage IV melanoma received nab-paclitaxel 150 mg/m(2) on days 1, 8, and 15 every 4 weeks or dacarbazine 1000 mg/m(2) every 3 weeks. The primary end point was progression-free survival (PFS) by independent radiologic review; the secondary end point was overall survival (OS). RESULTS: A total of 529 patients were randomized to nab-paclitaxel (n = 264) or dacarbazine (n = 265). Baseline characteristics were well balanced. The majority of patients were men (66%), had an Eastern Cooperative Oncology Group status of 0 (71%), and had M1c stage disease (65%). The median PFS (primary end point) was 4.8 months with nab-paclitaxel and 2.5 months with dacarbazine [hazard ratio (HR), 0.792; 95.1% confidence interval (CI) 0.631-0.992; P = 0.044]. The median OS was 12.6 months with nab-paclitaxel and 10.5 months with dacarbazine (HR, 0.897; 95.1% CI 0.738-1.089; P = 0.271). Independently assessed overall response rate was 15% versus 11% (P = 0.239), and disease control rate (DCR) was 39% versus 27% (P = 0.004) for nab-paclitaxel versus dacarbazine, respectively. The most common grade ≥3 treatment-related adverse events were neuropathy (nab-paclitaxel, 25% versus dacarbazine, 0%; P < 0.001), and neutropenia (nab-paclitaxel, 20% versus dacarbazine, 10%; P = 0.004). There was no correlation between secreted protein acidic and rich in cysteine (SPARC) status and PFS in either treatment arm. CONCLUSIONS: nab-Paclitaxel significantly improved PFS and DCR compared with dacarbazine, with a manageable safety profile.

Cutaneous adverse events in patients treated with BRAF inhibitor-based therapies for metastatic melanoma for longer than 52 weeks.

BACKGROUND: BRAF inhibitor-based therapies have been shown to induce cutaneous toxicities, with onset generally in the first 8-26 weeks of therapy. OBJECTIVES: To determine whether cutaneous toxicities persist in patients who have remained on BRAF inhibitor-based therapies for longer than 52 weeks, and therefore whether ongoing dermatology assessment is required. METHODS: All patients treated with the BRAF inhibitors vemurafenib or dabrafenib or combination BRAF inhibitor and mitogen-activated protein kinase kinase (MEK) inhibitor therapy at Westmead Hospital, Sydney, Australia underwent regular dermatological assessments for the duration of therapy. All patients enrolled in a clinical trial, and 18% of patients in the compassionate access scheme underwent a baseline assessment prior to commencement of therapy and every 4-8 weeks thereafter. Patients' adverse events were recorded in a specific database. RESULTS: Patients continued to develop cutaneous adverse events after 52 weeks of continuous therapy. Patients on single-agent BRAF inhibitor therapy suffered from Grover disease (45%), plantar hyperkeratosis (45%), verrucal keratosis (18%) and even cutaneous squamous cell carcinoma (16%). The most frequent adverse event seen in patients in the combination BRAF and MEK inhibitor group was an acneiform eruption (40%). CONCLUSIONS: Patients on BRAF inhibitor-based therapies need to continue to have regular dermatological follow-up independent of the duration of their therapy.

Ipilimumab-induced hypophysitis in melanoma patients: an Australian case series.

BACKGROUND: Ipilimumab (Yervoy; Bristol-Myers Squibb) is a novel fully humanised monoclonal antibody that blocks cytotoxic T-lymphocyte antigen 4, an immune checkpoint molecule, to augment anti-tumour T-cell responses. It is associated with significant immune-related side-effects including hypophysitis. AIM: We reviewed the clinical and biochemical characteristics of 10 patients with ipilimumab-induced hypophysitis (IH), and developed guidelines for the early detection and management of IH based on our experiences at three major teaching hospitals in Sydney. METHODS: All patients were evaluated at the Crown Princess Mary Cancer Centre and Department of Endocrinology, Westmead Hospital, Department of Endocrinology, Royal Prince Alfred Hospital, the Melanoma Institute Australia and Macarthur Cancer Therapy Centre, Campbelltown Hospital from 2010 to 2014. Relevant data were extracted by review of medical records. Main outcome measures included clinical features, hormone profile and radiological findings associated with IH, and presence of pituitary recovery. RESULTS: Ten patients were identified with IH. In four patients who underwent monitoring of plasma cortisol, there was a fall in levels in the weeks prior to presentation. The pituitary-adrenal and pituitary-thyroid axes were affected in the majority of patients, with the need for physiological hormone replacement. Imaging abnormalities were identified in five of 10 patients, and resolved without high-dose glucocorticoid therapy. To date, all patients remain on levothyroxine and hydrocortisone replacement, where appropriate. CONCLUSIONS: There is significant morbidity associated with development of IH. We suggest guidelines to assist with early recognition and therapeutic intervention.

Correlation of BRAF and NRAS mutation status with outcome, site of distant metastasis and response to chemotherapy in metastatic melanoma.

BACKGROUND: The prognostic significance of BRAF and NRAS mutations in metastatic melanoma patients remains uncertain, with several studies reporting conflicting results, often biased by the inclusion of patients treated with BRAF and MEK (MAPK) inhibitors. We therefore interrogated a historical cohort of patients free of the confounding influence of MAPK inhibitor therapy. METHODS: Patients with available archival tissue first diagnosed with metastatic melanoma between 2002 and 2006 were analysed. Mutational analysis was performed using the OncoCarta Panel. Patient characteristics, treatment outcome and survival were correlated with BRAF/NRAS mutation status. RESULTS: In 193 patients, 92 (48%) melanomas were BRAF-mutant, 39 (20%) were NRAS-mutant and 62 (32%) were wild-type for BRAF/NRAS mutations (wt). There was no difference in response to chemotherapy based on mutation status (35-37%). The distant disease-free interval (DDFI) was significantly shorter in patients with wt melanoma (27.9 months vs 35.1 for BRAF and 49.1 for NRAS) although this was not significant in multivariate analysis. Survival from stage IV melanoma diagnosis was not significantly different based on mutation status. The DDFI was significantly shorter in patients with BRAF(V600K/R) versus BRAF(V600E) melanoma in univariate and multivariate analyses. CONCLUSIONS: BRAF and NRAS mutation status does not influence survival in metastatic melanoma.

BRAF(V600E) protein expression and outcome from BRAF inhibitor treatment in BRAF(V600E) metastatic melanoma.

BACKGROUND: To examine the association between level and patterns of baseline intra-tumoural BRAF(V600E) protein expression and clinical outcome of BRAF(V600E) melanoma patients treated with selective BRAF inhibitors. METHODS: Fifty-eight BRAF(V600E) metastatic melanoma patients treated with dabrafenib or vemurafenib on clinical trials had pre-treatment tumour BRAF(V600E) protein expression immunohistochemically (IHC) assessed using the BRAF V600E mutant-specific antibody VE1. Sections were examined for staining intensity (score 1-3) and percentage of immunoreactive tumour cells, and from this an immunoreactive score (IRS) was derived (intensity × per cent positive/10). The presence of intra-tumoural heterogeneity for BRAF(V600E) protein expression was also assessed. BRAF(V600E) expression was correlated with RECIST response, time to best response (TTBR), progression-free survival (PFS) and overall survival (OS). RESULTS: Expression was generally high (median IRS 28 (range 5-30)) and homogeneous (78%). Expression of mutated protein BRAF(V600E) as measured by intensity, per cent immunoreactive cells, or IRS did not correlate with RECIST response, TTBR, PFS or OS, including on multivariate analysis. Heterogeneity of staining was seen in 22% of cases and did not correlate with outcome. CONCLUSION: In the current study population, IHC-measured pre-treatment BRAF(V600E) protein expression does not predict response or outcome to BRAF inhibitor therapy in BRAF(V600E) metastatic melanoma patients.

Systemic retinoids for the chemoprevention of cutaneous squamous cell carcinoma and verrucal keratosis in a cohort of patients on BRAF inhibitors.

BACKGROUND: The treatment of metastatic melanoma has changed greatly with the development of inhibitors targeted at the mutated BRAF kinase present in up to 50% of metastatic melanoma cases. These agents, vemurafenib and dabrafenib, have been shown to increase median survival. Unfortunately, they have also been associated with the development of verrucal keratosis (VK) and cutaneous squamous cell carcinoma (cuSCC). These lesions require surgical excision, and when a large number of these lesions need to be treated, it can significantly affect the patient's quality of life. OBJECTIVES: To determine if acitretin is suitable as a chemopreventative agent against the development of verrucal keratosis and cuSCC, in patients on BRAF inhibitors. METHODS: Patients treated with a BRAF inhibitor, vemurafenib or dabrafenib, for stage IV metastatic melanoma, who had undergone more than five surgical excisions to remove lesions suggestive of cuSCC, were offered the opportunity to commence acitretin as a chemopreventative agent. Patients were evaluated every 4 weeks. Clinical and histological data were collected. RESULTS: Eight patients, who had a total of 24 cuSCC removed, were included in the study. After commencement of acitretin, only five cuSCC were excised from two patients. The most significant reduction was in a patient who had developed 13 cuSCC over 10 months and only two cuSCC 3 months after commencing acitretin. No modifications in the dose of the BRAF inhibitor were made as a result of cuSCC in any of these patients. CONCLUSIONS: Acitretin should be considered as a chemopreventative agent for VK and cuSCC in patients taking BRAF inhibitors, before considering dosage reductions.

Cutaneous manifestations of dabrafenib (GSK2118436): a selective inhibitor of mutant BRAF in patients with metastatic melanoma.

BACKGROUND: Inhibitors of mutant BRAF are emerging as standard of care in patients with metastatic melanoma carrying relevant oncogenic mutations. Cutaneous reactions are frequent and significant. We conducted a systematic prospective dermatological review of all patients enrolled at a single institution in the phase I/II clinical trial of the mutant BRAF inhibitor dabrafenib (GSK2118436). OBJECTIVES: To identify the cutaneous manifestations of the BRAF inhibitor dabrafenib; to form diagnostic criteria to standardize the diagnosis of verrucal keratotic squamoproliferative lesions; and to bring awareness to the medical community of the importance of dermatological assessment of patients taking dabrafenib. METHODS: Patients enrolled in the phase I/II trial (n = 43) were monitored for the development of new skin lesions. Each new lesion was photographed, a clinical diagnosis recorded and, where appropriate, a biopsy taken. Human papillomavirus (HPV) and p16 immunohistochemistry analyses were performed. RESULTS: The most frequently observed lesions were verrucal keratotic squamoproliferative lesions (49%), Grover's disease (27%) and reactive hyperkeratotic lesions on the soles, at points of friction (22%). Eighteen squamous cell carcinomas (SCCs) occurred in 20% of patients. Most SCCs appeared between weeks 6 and 24 following commencement of therapy on both sun-damaged and nonsun-damaged skin. All SCCs were well differentiated, five were of the keratoacanthoma type, and two were SCC in situ. Other lesions observed included seborrhoeic keratoses, epidermal cysts, acneiform eruptions, hair loss and changes in hair structure. HPV was negative in 15 of the 16 tissues studied and p16 expression was higher in SCCs compared with verrucal keratoses. CONCLUSIONS: Administration of the mutant BRAF inhibitor dabrafenib is associated with induction of keratinocytic proliferation, which in some cases develops features of low-grade malignancy. Highly oncogenic HPV infection is unlikely to be a contributor to the formation of SCCs or verrucal keratoses.

Targeting BRAF for patients with melanoma.

The prognosis of patients with metastatic melanoma is poor and not influenced by systemic therapy with cytotoxic drugs. New targeted agents directed against the RAS-RAF-MEK-ERK pathway show promising activity in early clinical development and particular interest is focused on selective inhibitors of mutant BRAF, which is present in one half of the cases of metastatic melanoma. The majority of patients on early trials of these drugs develop secondary resistance and subsequent disease progression and it is, therefore, critical to understand the underlying escape mechanisms leading to resistance.

A phase I study of extended dosing with lomeguatrib with temozolomide in patients with advanced melanoma.

Lomeguatrib, an O(6)-methylguanine-DNA methyltransferase inactivator, was evaluated in an extended dosing regimen with temozolomide, designed according to pharmacodynamic data from previous studies. Patients with unresectable stage 3 or 4 cutaneous or unknown primary melanoma metastases were treated with lomeguatrib 40 mg, b.i.d. for 10 or 14 days and temozolomide 75-100 mg m(-2) on days 1-5. Drugs were administered orally with cycles repeated every 28 days, for up to six cycles. A total of 32 patients were recruited to the study. Lomeguatrib for 10 days with temozolomide 75 mg m(-2) was established as the optimal extended lomeguatrib dosing schedule, with haematological toxicity being dose limiting. There were two partial responses to treatment giving an overall response rate of 6.25%. Extending lomeguatrib administration beyond that of temozolomide requires a reduced dose of the latter agent. Only limited clinical activity was seen, suggesting no advantage for this regimen over conventional temozolomide administration in the treatment of melanoma.

O(6)-methylguanine-DNA methyltransferase depletion and DNA damage in patients with melanoma treated with temozolomide alone or with lomeguatrib.

We evaluated the pharmacodynamic effects of the O(6)-methylguanine-DNA methyltransferase (MGMT) inactivator lomeguatrib (LM) on patients with melanoma in two clinical trials. Patients received temozolomide (TMZ) for 5 days either alone or with LM for 5, 10 or 14 days. Peripheral blood mononuclear cells (PBMCs) were isolated before treatment and during cycle 1. Where available, tumour biopsies were obtained after the last drug dose in cycle 1. Samples were assayed for MGMT activity, total MGMT protein, and O(6)-methylguanine (O(6)-meG) and N7-methylguanine levels in DNA. MGMT was completely inactivated in PBMC from patients receiving LM, but detectable in those on TMZ alone. Tumours biopsied on the last day of treatment showed complete inactivation of MGMT but there was recovery of activity in tumours sampled later. Significantly more O(6)-meG was present in the PBMC DNA of LM/TMZ patients than those on TMZ alone. LM/TMZ leads to greater MGMT inactivation, and higher levels of O(6)-meG than TMZ alone. Early recovery of MGMT activity in tumours suggested that more protracted dosing with LM is required. Extended dosing of LM completely inactivated PBMC MGMT, and resulted in persistent levels of O(6)-meG in PBMC DNA during treatment.

Long-term survival and occasional regression of distant melanoma metastases after adrenal metastasectomy.

BACKGROUND: Human melanoma cells express high-affinity glucocorticoid receptors, and adrenalectomy has been shown to have antimelanoma effects in animal models. Long-term regression of distant metastatic melanoma was observed in one patient after bilateral adrenalectomy, prompting a review of adrenalectomy for melanoma metastases performed at this center. METHODS: A retrospective study in which all patients treated at the Sydney Melanoma Unit and recorded as having adrenal gland metastases between January 1987 and January 2004 were identified and their survival analyzed. RESULTS: One hundred eighty-six patients with adrenal gland metastases were identified. Adrenalectomy was performed in 23 patients; the other 163 patients were treated nonsurgically. The adrenal glands were the sole site of disease in five patients. All symptomatic patients were free of pain after recovery from the surgical procedure. Thirteen patients were rendered clinically and radiologically disease-free by their surgery. There was no postoperative mortality within 30 days. Median overall survival after adrenalectomy was 16 months (2-year survival, 39%), compared with 5 months for patients with documented adrenal metastases treated nonsurgically (P < .00001). In one patient, nonresected visceral metastases elsewhere regressed completely after bilateral adrenalectomy; he remained well and free of disease 80 months after adrenalectomy. Regression of distant visceral metastatic disease also occurred in a second patient after unilateral adrenalectomy. CONCLUSIONS: Adrenalectomy for melanoma metastatic to the adrenal gland provides good palliation of symptoms and is associated with prolonged survival in a selected cohort of patients. We report for the first time sustained complete regression of distant metastatic melanoma after bilateral adrenalectomy, suggesting a possible role for adrenal hormones in modifying melanoma progression in certain patients.

Purine deoxynucleoside toxicity in nondividing human lymphoid cells.

Cultured leukemic T-lymphoblasts, incubated in the presence of inhibitors of adenosine deaminase, are exquisitely sensitive to growth inhibition by deoxyadenosine. An analogy between this phenomenon and human combined immunodeficiency disease associated with inborn adenosine deaminase deficiency and the use of inhibitors of adenosine deaminase in the management of T-cell acute lymphoblastic leukemia has been noted. These phenomena are believed to reflect accumulation of high intracellular concentrations of deoxyadenosine triphosphate (dATP) following phosphorylation of deoxyadenosine, inhibiting replicating T-cells. In an attempt to extend these observations to noncultured, nonleukemic T-cells, we studied deoxyadenosine metabolism in human thymocytes. Human thymuses were separated into large replicating and small nondividing cell types by centrifugal elutriation. Both thymocyte subpopulations elevated in their dATP pools on incubation with microM concentrations of deoxyadenosine in the presence of erythro-9-[3-(2-hydroxynonyl)]adenosine, an inhibitor of adenosine deaminase. These dATP pool rises were similar in extent to those found in cultured leukemic T-lymphoblasts. However, the finding that small nonreplicating thymocytes elevate their dATP pool was unexpected. This prompted study of unstimulated peripheral blood lymphocytes. These cells (T and non-T) showed a similar elevation of their dATP pool on incubation with deoxyadenosine. Furthermore, these nondividing peripheral blood lymphocytes were killed by microM concentrations of deoxyadenosine in the presence of an inhibitor of adenosine deaminase. The biochemical mechanism of this G0-phase cell death is not known. These findings provide impetus for the investigation of adenosine deaminase inhibitors as lympholytic immunosuppressants or as agents to noncycling malignant lymphoid cells.

Flow cytometric analysis of adenosine analogue lymphocytotoxicity.

The induction of G1-phase arrest in T-lymphoblasts by cytostatic concentrations of 2'-deoxyadenosine (R. M. Fox, R. F. Kefford, E. H. Tripp, and I. W. Taylor, Cancer Res., 41: 5141-5150, 1981) prompted a flow cytometric analysis of the cell cycle effects of three other adenosine analogues with known effects on polyadenylated RNA metabolism in an attempt to further explore the nature of 2'-deoxyadenosine 5'-triphosphate-mediated lymphotoxicity. Cytostatic concentrations of 9-beta-D-arabinofuranosyladenine induced an S-phase block, while 3'-deoxyadenosine (cordycepin) and tubercidin (7-deazaadenosine) induced a cycle-nonspecific block. Furthermore, total cellular RNA content was unaltered by 2'-deoxyadenosine or 9-beta-D-arabinofuranosyladenine, but 3'-deoxyadenosine and tubercidin caused a marked reduction in total cellular RNA at minimally cytostatic concentrations. At concentrations of 0.3 to 20 microM, all of these nucleosides were toxic to nondividing peripheral blood lymphocytes, suggesting that in these cells their mechanism of action does not involve reactions associated with DNA replication. Inhibition of polyadenylated RNA metabolism by triphosphate derivatives of adenosine analogues may account for lymphocytotoxicity in nondividing cells, but the demonstrated diverse effects of these nucleosides on nucleic acid metabolism in dividing cells preclude elucidation of the mechanism of the unique induction of G1-phase arrest by 2'-deoxyadenosine.