The ABCB6 mutation p.Arg192Trp is a recessive mutation causing the Lan- blood type.

BACKGROUND AND OBJECTIVE: The membrane transporter ABCB6 has recently been shown to carry the high-frequency red-blood-cell (RBC) antigen Lan. All the Lan- individuals genotyped so far have inherited two recessive null mutations in ABCB6. The finding of a family with the Lan- blood type occurring in two successive generations prompted this study. METHODS: Mutations in ABCB6 were searched by Sanger sequencing of exons and flanking intronic regions. Expression analysis of the Lan antigen was carried out by serology and flow cytometry. PCR-RFLP genotyping and Western blot analysis were also applied. RESULTS: All the Lan- members of this family were homozygous for c.574C>T, p.Arg192Trp in ABCB6 while the Lan+ members were heterozygous for this missense mutation encoded by the SNP rs149202834. Homozygosity for p.Arg192Trp was associated not only with absence of the Lan antigen, but also of the ABCB6 transporter in RBC membrane. The complete absence of Lan expression resulting from p.Arg192Trp homozygosity was confirmed by the subsequent identification of five unrelated Lan- individuals who were homozygous for this mutation and who developed an anti-Lan. We also provide evidence that three other single amino acid mutations in ABCB6 (c.826C >T, p.Arg276Trp; c.85_87delTTC, p.Phe29del; c.1762G >A, p.Gly588Ser) may also define ABCB6 null alleles. CONCLUSION: p.Arg192Trp is the first ABCB6 missense mutation causing the Lan- blood type and appears to be a relatively frequent cause of this rare blood type. Like the previously reported frameshift, nonsense and essential splice-site mutations in ABCB6, this missense mutation is recessive and defines an ABCB6 null allele. Other single amino acid mutations in ABCB6 may also cause the Lan- blood type.

Dose-finding study of weekly 24-h continuous infusion of 5-fluorouracil associated with alternating oxaliplatin or irinotecan in advanced colorectal cancer patients.

PURPOSE: To determine maximum tolerated dose, safety and efficacy of weekly 24 h infusional 5-fluorouracil (5-FU) combined alternately with oxaliplatin and irinotecan. PATIENTS AND METHODS: Advanced colorectal carcinoma patients in first- or second-line chemotherapy received increasing doses of 5-FU (weekly 24 h continuous intravenous infusion without leucovorin) on days 1, 8, 15 and 22, irinotecan days 1 and 15; and oxaliplatin days 8 and 22, every 35 days. RESULTS: Thirty-four patients received 175 cycles. The median age was 64 years (range 47-78). Eighteen per cent of patients had the primary tumor in the rectum, with a median of one disease site (range one to three), and liver involvement in 88% and lung in 38%. Six (18%) patients had chemotherapy for prior advanced disease. The most frequent grade 3-4 toxicity was neutropenia (41% of patients), but the regimen was well tolerated clinically, with febrile neutropenia in two patients and grade 4 neutropenia lasting >7 days in one; grade 3-4 diarrhea, nausea and vomiting in 6% of patients; grade 3-4 peripheral neuropathy in 9% of patients. Seventeen patients had a partial response (50%; 95% confidence interval 33%-67%), 13 had stable disease and one had progressive disease. Five patients underwent metastatic surgical resection after tumor shrinkage. Median response duration was 14 months (range 4.7-29.2+) and median time to progression was 11.3 months (range 1.1+-30.7+). CONCLUSIONS: This combination three-drug regimen is feasible and well tolerated without toxicity overlap. Preliminary antitumor activity compares well with standard double combinations, with an unusually long median time to progression. The recommended dose is 5-FU 3000 mg/m(2), weekly for 4 weeks, irinotecan 100 mg/m(2) days 1 and 15, oxaliplatin 80 mg/m(2) days 8 and 22. Further assessment of antitumor activity and safety is warranted.

Phase II trial of a paclitaxel-carboplatin combination in recurrent squamous cell carcinoma of the head and neck.

OBJECTIVE: Twenty-seven patients with recurrent squamous cell carcinoma of the head and neck were entered in a multicenter study to determine the efficacy of the paclitaxel-carboplatin association. METHODS: Standard eligibility criteria applied, i.e. measurable disease, and chemotherapy given as induction treatment or concomitant chemoradiotherapy was allowed if completed more than 6 months prior to the study. Every 21 days, paclitaxel 175 mg/m(2) and carboplatin AUC 6 were administered. The patient group included 3 females and 24 males with a median age of 61 years (range 39-75 years). RESULTS: All patients were assessable for toxicity and 24 for responses. Main grade 3-4 toxicities were: neutropenia (62.9%), febrile neutropenia (18.5%), anemia (11.1%), thrombocytopenia (14.8%), mucositis (7.4%) and vomiting (7.4%). Among the intent-to-treat population, 29.6% of patients had an objective response, with a median response duration of 4.2 months (range 1-5.7 months). Stable and progressive disease were observed in 11.1 and 48.1% of patients, respectively. The median overall survival was 7.2 months (range 0.5-10.9 months). CONCLUSION: From these data, paclitaxel-carboplatin seems to have an activity in recurrent squamous cell carcinoma of the head and neck, but the high level of toxicity highlights the need to search for a safer chemotherapy combination.