Current trends in initial management of hypopharyngeal cancer: the declining use of open surgery

Squamous cell carcinoma of the hypopharynx represents a distinct clinical entity. Most patients present with significant comorbidities and advanced-stage disease. The overall survival is relatively poor because of high rates of regional and distant metastasis at presentation or early in the course of the disease. A multidisciplinary approach is crucial in the overall management of these patients to achieve the best results and maintain or improve functional results. Traditionally, operable hypopharyngeal cancer has been treated by total (occasionally partial) laryngectomy and partial or circumferential pharyngectomy, followed by reconstruction and postoperative radiotherapy in most cases. Efforts to preserve speech and swallowing function in the surgical treatment of hypopharyngeal (and laryngeal) cancer have resulted in a declining use of total laryngopharyngectomy and improved reconstructive efforts, including microvascular free tissue transfer. There are many surgical, as well as nonsurgical, options available for organ and function preservation, which report equally effective tumor control and survival. The selection of appropriate treatment is of crucial importance in the achievement of optimal results for these patients. In this article, several aspects of surgical and nonsurgical approaches in the treatment of hypopharyngeal cancer are discussed. Future studies must be carefully designed within clearly defined populations and use uniform terminology and standardized functional assessment and declare appropriate patient or disease endpoints. These studies should focus on improvement of results, without increasing patient morbidity. In this respect, technical improvements in radiotherapy such as intensity-modulated radiotherapy, advances in supportive care, and incorporation of newer systemic agents such as targeted therapy, are relevant developments.

Contemporary management of sinonasal cancer

BACKGROUND

Sinonasal cancer is a relatively uncommon entity encountered by head and neck oncologists, rhinologists, and skull base surgeons. Recent innovations in surgical and nonsurgical therapeutic modalities raise the question of whether there has been any measurable improvement for treatment outcomes.

METHODS

A retrospective review of data from recent studies that focus on surgery, radiation, and chemotherapy, or combinations thereof, was conducted.

RESULTS

Surgery continues to be the preferred treatment and provides the best results, albeit with an inherent bias based on patient selection. For advanced disease (T4 lesions), the survival rate remains only modest. Complications of treatment, including both surgical and radiation therapy, have been reduced.

CONCLUSIONS

There is a need to improve the efficacy of treatment for this disease. Recommendations for the future direction of therapeutic investigations are outlined.

Postoperative strategies after primary surgery for squamous cell carcinoma of the head and neck

This review discusses the role of adjuvant treatment after curative surgery for patients with head and neck squamous cell carcinoma (HNSCC). In general, patients with unfavourable prognostic factors have a high-risk of loco-regional recurrence and subsequent worse survival after surgery alone and are therefore considered proper candidates for adjuvant treatment by either postoperative radiotherapy alone or postoperative chemoradiation. Selection of the most optimal adjuvant treatment strategy should be based on the most important prognostic factors. In this review, the different treatment strategies will be discussed in general. More specifically, we will discuss the role of the interval between surgery and radiotherapy, the overall treatment time of radiation, the selection of target volumes for radiation and the value of adding concomitant chemotherapy to postoperative radiation.

Head and neck squamous cell carcinomas in HIV-positive patients: a preliminary investigation of viral associations

Oncogenic human papillomaviruses (HPVs) are associated with oropharyngeal squamous cell carcinoma (SCC). Infection with human immunodeficiency virus (HIV) increases susceptibility to opportunistic infections and viral-promoted cancers. The prevalences of HPV, herpes simplex virus (HSV), Epstein-Barr virus (EBV), and human herpesvirus-8 (HHV-8) have not been established for head and neck squamous cell carcinoma in HIV-positive patients (HIV+ HNSCC). We have observed that HIV+ HNSCC tend to contain numerous multinucleated tumor giant cells, this finding has not been described previously. The goal of this study is to test for these oncogenic viruses in a small cohort of retrospectively identified patients with HIV infection, and to compare histologically these cancers to a control group of HNSCC patients. Tumors were reviewed histologically and compared to a control group of 102 patients with HNSCC (serologically untyped or HIV negative). Polymerase chain reaction (PCR) was performed on formalin-fixed, paraffin-embedded HIV+ HNSCC samples from combined 25 patients in two institutions. In situ hybridization was performed to identify EBV (EBER) and immunohistochemistry was performed to detect HSV-1, HSV-2, HHV-8, and HIV-related proteins (Nef, p24). The study sample consisted of 34 HIV+ patients with HNSCC from Montefiore Medical Center, and six HIV+ HNSCC patients from Hospital Clinic, University of Barcelona; 24 (60%) men and 16 (40%) women. The larynx was most commonly involved (65%, n = 26); followed by the oropharynx (22.5%, n = 9). Four carcinomas arose from the oral cavity (10%) and one from the nasal cavity (2.5%). Histologically, multinucleated tumor giant cells were more common in the HIV+ group (39/40, 97.5%) than the control group (27/102, 26%, p 0.001, chi-square). HPV was detected in 6 of 25 (24%) HNSCC tumors by PCR, five were typed as HPV 16 and one as HPV 26/69; five of these tumors (83%) were located in the oropharynx. EBV, HSV-1, HSV-2, and HHV-8 were detected only infrequently in tumor cells. Nef protein was detected in tumor cells in 7 of 21 (33.3%) cases; p24 was not detectable in 6 tumors studied. There were no significant associations between HPV positive tumors and co-infections with other viruses. This study is consistent with other reports that suggest an increased incidence of laryngeal carcinoma for HIV+ patients. HPV was detected in 24% of HIV+ HNSCC, however, the number of tumors with amplifiable DNA (n = 25) is too small to allow for conclusions. EBV, HSV-1, HSV-2, and HHV-8 are uncommon in HIV+ HNSCC; it is unlikely that these viruses have a promoting effect. MNTCG are significantly common in HIV+ HNSCC, but there is overlap in MNTCG counts with the control group and therefore this finding cannot be used as a biomarker of HIV infection.

Phase II randomized trial of bortezomib (B) plus irinotecan (I) or B with addition of I at progression in recurrent (R) or metastatic (M) squamous cell carcinoma of the head and neck (SCCHN) (E1304): A trial of the Eastern Cooperative Oncology Group

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Background: B, inhibits activation of NF- κβ and inhibits growth of SCCHN cell lines. NF-κβ dysregulation contributes to chemoresistance, including I. Pretreatment with B increases tumor sensitivity to I in vitro. Methods: Eligibility: 0–1 prior chemo regimens, ECOG PS 0–1. Pts randomized to B 1.3 mg/m2 IV d 1, 4, 8, 11 and I 125 mg/m2 IV d 1, 8 every 21 days (Arm 1) or B with addition of I at time of progression (Arm 2). Primary endpoint was response rate (RR) using RECIST and Simon's optimal 2-stage design. Results: 62 pts analyzable (Arm 1, N = 23; Arm 2, N = 39) of 71 enrolled . Pt. characteristics: median age 61 yrs., ECOG PS 1 - 53 %, and 71% had prior chemo. To date, RR (all PRs) 13% Arm 1 and 3% Arm 2 with SD 17% Arm 1 and 23% Arm 2. However, 3 patients remain on active therapy in Arm 2 and PFS and updated RR will be reported. 7 patients (including 3 pts on Arm 2) received 6–10 cycles of therapy. No responses in all 11 analyzable pts in Arm 2 with I added at progression. Median OS 9.1 months - Arm 1 and 7.3 months - Arm 2. Toxicity of B + I (125 mg/m2): grade 3/ 4 neutropenia (31%), vomiting (15%), diarrhea (15%), dehydration (23%). Grade 5 toxicity in 3 pts, 2 possibly related to therapy. Trial amended to decrease I to 90 mg/m2 3 patients (33%) - grade 3 / 4 diarrhea; no grade 3/ 4 neutropenia or grade 5 toxicities. Arm 2: grade 3 / 4 fatigue (15%). Conclusions: B alone is well tolerated. To date, RR low but prolonged stable disease noted in some pts. B in combination with I is a toxic regimen with disappointing activity.

[Table: see text]

A phase 1 open-label, accelerated dose-escalation study of the hypoxia-activated prodrug AQ4N in patients with advanced malignancies

PURPOSE

AQ4N is a novel prodrug that is selectively bioreduced to AQ4, a topoisomerase II inhibitor, in hypoxic tumor. This study assessed the maximum tolerated dose and pharmacokinetics of AQ4N when administered weekly in patients with advanced cancers.

EXPERIMENTAL DESIGN

AQ4N was administered as a 30-minute i.v. infusion on days 1, 8, and 15 of a 28-day cycle in eight dose cohorts ranging from 12 to 1,200 mg/m(2). Accelerated titration design was used and the maximum tolerated dose was defined as the highest dose at which fewer than two of six patients had a dose-limiting toxicity.

RESULTS

Sixteen patients were treated with cumulative doses of AQ4N ranging from 61.6 through 9,099.1 mg/m(2). A single patient per cohort was treated up to 384 mg/m(2) without toxicities. At 1,200 mg/m(2), two of five patients experienced a dose-limiting toxicity (grade 5 respiratory failure and grade 3 fatigue). Five cohort assigned patients were treated without toxicity at 768 mg/m(2), establishing this dose as the maximum tolerated dose. Among the most common adverse events observed were fatigue (38%), diarrhea (31%), nausea (25%), vomiting (25%), and anorexia (13%). Anticipated blue coloration of body fluids or skin was observed in all patients. The pharmacokinetics of AQ4N were dose proportional over all doses studied. Three patients experienced stable disease, including a patient with collecting duct renal cancer stable for 25 months.

CONCLUSION

AQ4N is well tolerated when administered weekly on a 3-of-4-week schedule at 768 mg/m(2). Further combination studies investigating the safety and efficacy of AQ4N are ongoing.

Clinical and translational studies of depsipeptide (romidepsin), a histone deacetylase (HDAC) inhibitor, in patients with squamous cell carcinoma of the head and neck (SCCHN): New York Cancer Consortium Trial P6335

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Background: Unresectable recurrent and metastatic SCCHN is incurable and associated with dismal prognosis. Our objective is to evaluate the clinical activity of depsipeptide (DEP) and its effects of on PBMCs, SCCHN tumors and oral mucosa tissues in an NCI/CTEP sponsored phase II trial. Methods: Eligibility criteria include PS 0–2, any number of prior therapies and no history of significant cardiovascular disease. DEP was administered at 13 mg/m2 IV over 4 hrs on days 1, 8, and 15 of 28 day cycles. A two-stage design was utilized, with commencement to the second stage (total 46 pts) if at least 8 of 18 pts achieve disease control at 8 weeks by RECIST. Results: To date, 10 pts (7M/3F) have been accrued, all with samples for correlative studies. Two pretreated pts (2 and 4 prior therapies for recurrent/metastatic disease) have achieved disease stabilization, including one with clear histone H3 hyperacetylation in PBMCs immediately following the first 4 hr infusion of DEP. Common toxicities to date have included fatigue and weakness, usually mild. Myelosuppression is uncommon. Aside from G3 hypotension in 1 pt, no cardiovascular toxicities have been attributed to DEP. To date, 2 of 2 pairs of pre- and post-treatment (cycle 1, day 16) biopsy specimens have demonstrated increased expression of p21Waf1/Cip1 by immunohistochemistry post-DEP, consistent with HDAC inhibition by DEP in tumor cells. Additionally, 3 pairs of tumor biopsies and 4 pairs of mucosal brush biopsies have been analyzed by differential gene expression profiling using microarrays containing 27,323 cDNA clones; 208 cDNA clones of interest appear to be upregulated in response to DEP in at least 3 of the 7 comparisons. Analysis also includes CpG island methylation status of candidate tumor suppressor loci in tumor and mucosal tissues. Conclusions: DEP appears well tolerated by SCCHN pts, with infrequent myelosuppression and minimal if any cardiovascular toxicity in pts without pre-existing disease. Effects of DEP on PBMCs, tumor and mucosal tissues are consistent with HDAC inhibition in vivo. Accrual to the clinical trial is ongoing. Supported by ASCO Career Development Award, NIH CA110342 and N01-CM-62204.

No significant financial relationships to disclose.

A phase II trial of VNP40101M in patients with relapsed or refractory small cell lung cancer (SCLC) with or without brain metastases

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Background: Relapsed or refractory SCLC patients (pts) have a poor prognosis. Median survival at relapse is 2–3 months; brain metastases (mets) are common. Alkylating agents have demonstrated activity in SCLC. Cloretazine is a new alkylator that is active against selected alkylating agent resistant tumor cell lines. Xenograft models show distribution across the blood-brain barrier. This study investigates VNP40101M safety and activity in SCLC patients who have relapsed or are refractory to standard 1st line chemotherapy. Methods: Pts are entered in 2 groups based on response to prior chemotherapy: sensitive relapse (chemotherapy-free interval >3 months); or resistant/refractory (chemotherapy-free interval ≤3 months). Eligibility criteria include: measurable or evaluable disease; life expectancy of ≥2 months; and ECOG PS of 0–2. Pts with brain mets are eligible. 31 pts received VNP40101M IV at a starting dose of 125 mg/m2/wk × 3, every 6 weeks. Due to a high incidence of grade 3–4 thrombocytopenia (34%), an amended protocol reduced the dose of VNP40101M to 100 mg/m2 at the same schedule. 13 pts received the reduced dose. Pts are evaluated by RECIST criteria after each 6-week cycle. Results: 44 of 87 planned pts have been treated at 7 sites. Of 41 evaluable pts, 21 patients have sensitive relapse disease, and 20 have resistant/refractory disease. Median age is 64 years (44–86). Median number of cycles received is 1 (1–3). Grade 3–4 thrombocytopenia was seen in 11/31 pts at the 125 mg/m2 dose and 3/13 pts at the 100 mg/m2 dose. Gr 3–4 non-hematologic toxicity is rare, except for fatigue (10%) and GI effects (10%). The response rate (PR) is 6/21 (29%) in the sensitive relapse group, and 1/20 (5%) in the resistant/refractory group. 2/6 PRs, in the sensitive relapse group, occurred at the reduced dose level. 16 pts had brain mets at study entry. Of these, there were 3 PRs (2 with measurable regression of brain mets) and 3 stable diseases. Conclusions: The study is ongoing to confirm efficacy and safety. VNP40101M has activity against SCLC in the 2nd line setting including pts with brain metastases; further study is warranted.

No significant financial relationships to disclose.

A rare case of primary lung adenocarcinoma detected by routine liquid-based cervical cytology

Cervical cytology is mainly used for the screening and detection of early cervical cancers and its precursors. Rarely, detection of malignant cells in cervical cytology specimens is the first manifestation of an extrauterine (EU) malignancy. We report a case of a 49-year-old female in which adenocarcinoma initially diagnosed on routine, liquid-based cervical cytology led to the detection of a primary lung cancer.

Erlotinib, an effective epidermal growth factor receptor tyrosine kinase inhibitor, induces p27KIP1 up-regulation and nuclear translocation in association with cell growth inhibition and G1/S phase arrest in human non-small-cell lung cancer cell lines

Erlotinib, a small-molecule epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor, has been shown to have potent antitumor effects against human non-small-cell lung cancer (NSCLC) cell growth; however, the mechanism of such an effect is not elucidated. Here, we demonstrate that erlotinib-induced cell growth inhibition in EGFR high-expressing human H322 NSCLC cells was accompanied by G1/S phase arrest, which was largely caused by a decrease in expression of G1/S-related cyclins, suppression of activities of cyclin-dependent kinase (CDK) 2 and CDK4, induction of CDK inhibitor p27(KIP1), and retinoblastoma hypophosphorylation. To further understand the role of p27(KIP1) in G1/S arrest and cell growth inhibition by erlotinib, we determined its effect on the expression of p27(KIP1) at transcriptional and posttranscriptional levels. Studies using real-time reverse transcription-polymerase chain reaction analysis and p27 promoter-driven luciferase reporter showed that erlotinib treatment resulted in the promotion of p27 gene transcription. In addition, erlotinib treatment led to an increase in p27(KIP1) half-life by inhibiting p27(KIP1) phosphorylation at Thr187 and by down-regulating Skp2 expression. Furthermore, immunofluorescence staining and cell fractionation showed that erlotinib treatment led to p27(KIP1) translocation to the nucleus. Knockdown of p27(KIP1) expression with p27(KIP1) small interfering RNA significantly abrogated erlotinib-induced G1 phase arrest and cell growth inhibition, suggesting that induction of p27(KIP1) is required for G1 arrest and cell growth inhibition by erlotinib. It is noteworthy that we found that G1 arrest and p27(KIP1) up-regulation by erlotinib occurred in the tested sensitive cell lines but to a lesser extent in the resistant cell lines. Taken together, these results suggest that erlotinib inhibits human NSCLC cell growth predominantly by inducing p27(KIP1) expression and by suppressing cell-cycle events involved in the G1/S transition.

Differential tissue and subcellular expressionof ERM proteins in normal and malignant tissues: cytoplasmic ezrin expression has prognostic signficance for head and neck squamous cell carcinoma

BACKGROUND

Members of the ezrin-radixin-moesin (ERM) protein family regulate cellular shape, motility, and proliferation and potentially influence ability to metastasize. We investigated the correlation between ERM subcellular localization and survival in patients with squamous cell carcinoma (SCC) METHODS: Tissue microarrays (TMAs) were constructed from paraffin-embedded tissue. TMA sections were evaluated for ERM protein expression immunohistochemically. The results were compared across clinical and histopathologic variables

RESULTS

ERM staining results for 47 patients showed that cytoplasmic ERM expression was prevalent in tumors (>92%). Whereas ezrin and moesin also localized to the membrane, only willin was found in the nucleus of tumors. Multivariable Cox regression analysis demonstrated that strong cytoplasmic ezrin expression was independently associated with poorer survival (p = .04, hazard ratio 1.82)

CONCLUSIONS

Both level of expression and subcellular localization of ERM proteins may be important indicators of clinical outcome in SCC. This pilot study justifies the need for an expanded validation study of ERM proteins and clinical outcome.

Squamous cell carcinoma of the head and neck (SCCHN) in patients reporting human immunodeficiency virus (HIV) infection: A retrospective case series

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Background: Although Squamous Cell Carcinoma of the Head and Neck (SCCHN) is a non-AIDS defining malignancy, its risk is greater in HIV-positive populations for unclear reasons. Very limited data exist on the clinical presentation, treatment toxicities and outcomes of HIV infected pts with SCCHN, a population frequently excluded from participation in clinical trials. Methods: We present a large case series of HIV infected pts with SCCHN who were recently treated at a single institution. Retrospective chart reviews were performed by treating physicians. Results are reported with descriptive statistics. Results: Thirty individuals with SCCHN reporting HIV infection have been treated by the collaborating physicians from 1997–2005; all were smokers. The average age at diagnosis of SCCHN was 49.3 years (range 33–62), and interestingly, a relatively large number were female (13 of 30, 43%). The median CD4 count of pts was 374/μL, and most pts reported a history of antiretroviral therapy. The most frequent sites of primary disease were the larynx (13 pts, 43%, mostly supraglottic) and oropharynx (13 pts, 43%). Although most patients (87%) presented with advanced (stage III and IV) disease, a few (4 pts, 13%) had stage II disease. Although 12 pts underwent surgical resections for primary treatment, 16 pts underwent primary nonsurgical therapy, including 8 pts treated with chemoradiotherapy. Therapy related toxicities were expected and did not appear different from those observed in immunocompetent individuals. Eight pts had recurrence (7 locoregional/1 distant), and 5 pts died from recurrent/metastatic disease. Three pts had second primary cancers. Conclusions: HIV-infected individuals with SCCHN are generally young smokers, both male and female, receiving active treatment against HIV. The detection of a proportion of pts with early stage disease further supports the role for aggressive smoking cessation counseling and screening efforts for SCCHN in HIV infected populations. Additionally, HIV infection is not a contraindication to aggressive organ-preserving regimens for SCCHN pts with otherwise good functional status. A case-control clinical and pathologic study of SCCHN in HIV infection is planned.

No significant financial relationships to disclose.

Aerodigestive cancers in HIV infection

PURPOSE OF REVIEW

Aerodigestive (lung, head and neck) cancers are among the most prevalent and deadly neoplasms worldwide, and the incidence rates are rising. Given the improvements in life expectancy of persons with HIV/AIDS when treated with highly active antiretroviral agents, persons with HIV infection are therefore increasingly likely to develop these malignancies. This chapter focuses on the epidemiology of these malignancies and reviews the most recent literature and current understanding of the causes and treatment of these malignancies in HIV-positive populations.

RECENT FINDINGS

Aerodigestive neoplasms in patients with HIV infection are associated with younger age at diagnosis, cigarette smoking, advanced stage at presentation, and a more aggressive clinical course. The causes of these cancers, aside from the traditional risk factors of tobacco and alcohol exposure, are not clear. Although these neoplasms are non-AIDS defining, factors that might contribute to risk include HIV-related immunosuppression and co-infection with high-risk human papillomavirus subtypes.

SUMMARY

With continued improvements in therapies for HIV, the expected increase in incidence and mortality of persons with HIV infection from aerodigestive malignancies will likely become a major public health concern. Given the younger age of HIV-infected patients with these malignancies and the apparently higher rates of smoking among HIV-positive individuals, aggressive smoking cessation efforts should be directed to this high-risk population.

Exogenous expression of H-cadherin in CHO cells regulates contact inhibition of cell growth by inducing p21 expression

The impact of the cadherins in human cancers is becoming better understood. However, few studies have directly tested the hypothesis that H-cadherin, a tailless cadherin, is actually a tumor suppressor, and no published studies have addressed the question of how H-cadherin suppresses cellular transformation. We report here the influence that exogenous expression of H-cadherin imposes on growth, morphology, clonogenicity and tumorigenicity of Chinese hamster ovarian (CHO) cells. H-cadherin expression in CHO cells resulted in tighter adhesion of multicellular aggregates and reduced cell proliferation. In addition to enhancement of cell-cell adhesion, exogenous H-cadherin expression also inhibited cell proliferation and the ability to form colonies in soft agar. Furthermore, expression of H-cadherin in CHO cells led to complete suppression of subcutaneous tumor growth in nude mice. Seeding the H-cadherin expressing CHO cells on culture plates coated with recombinant H-cadherin amino-terminal fragments resulted in inhibition of cell proliferation that was accompanied by increased expression of the cdk inhibitor p21. These results support the role of H-cadherin as a tumor suppressor participating in contact inhibition of cell growth, possibly by inducing p21 expression.

Indirect measurements of differential gene expression with cDNA microarrays

The use of universal RNA reference sets is an increasingly common approach to molecular classification studies with cDNA microarrays. Here we evaluated the reliability of indirect measurements of fluorescence ratios with a common RNA reference as a means of identifying differentially expressed genes. Comparisons of direct and indirect measures of differential gene expression showed a strong overall correlation in fluorescence ratio measurements but also a high degree of false positives in our indirect measurements. These results indicated that the application of more stringent ratio filters may be required when assessing differential gene expression utilizing a common RNA reference in classification studies.

Chemopreventive therapeutics. Inhalation therapies for lung cancer and bronchial premalignancy

The lung cancer epidemic is not expected to abate in the next two decades. Smoking cessation campaigns have not been successful in reducing the prevalence of smoking to < 25% of the adult population in the US. Among high school students, the prevalence of smoking is increasing (27.5% in 1991; 36.4% in 1997) (43). In addition, only 1 in 8 heavy smokers develop lung cancer and about 20% of patients with lung cancer have no history of active or passive smoking, thus indicating that genetic predisposing factors and other unidentified carcinogens play a crucial role in the etiology of this disease. The bronchial epithelium is like an internal skin where lung cancer originates after chronic exposure to airborne carcinogens in a predisposed host. Although the bronchial epithelium is not readily examinable, it is easily accessible to therapeutic intervention by using inhaled therapeutics. We hope to extend our findings using direct wild-type p53 gene replacement via intratracheal and aerosolized administrations in mice to NSCLC patients with p53 mutations. We also plan on utilizing aerosolized chemical agents to activate endogenous mechanisms of cytoprotection. If, in clinical trials, evidence of effective cytoprotection is observed in the absence of intolerable side effects, further exploration of this new strategy for the control and prevention of a neoplastic disease that accounts for a third of all cancer-related deaths will be fully justified.

The BCL2-family of protein ligands as cancer drugs: the next generation of therapeutics

Selective aberrant cell suicide (ie., apoptosis or programmed cell death) is a hallmark of "nonneoplastic" tissue. In cells that have clonally evolved or in common parlance "cancer cells", apoptosis is either itself aberrant or completely inhibited. Strategies to enhance apoptosis under conditions of cancer cellular stress is an evolving and actively investigated area of experimental therapeutics. Bcl2 proteins are key mediators of the process of apoptosis and ligands to these family of proteins have been described using modern combinatorial, computational and evolutionary small molecule screening approaches. Crystallization of several of the Bcl2 family members has provided clarification of the role of these ligands and provided a clearer mechanism of action for the consequences of ligand binding. In several cases, these ligands (e.g., HA14-1, 2-methoxy antimycin A) induce apoptosis even under conditions of Bcl2 overexpression and if developed preclinically will be promising anticancer agents. This rationale becomes even more striking when one observes overexpression of Bcl2 in 70% of breast cancer, 30-60% of prostate cancer, 80% of B-cell lymphomas, 90% of colorectal adenocarcinomas, and many other forms of cancer.

Phase I study of amifostine as a cytoprotector of the gemcitabine/cisplatin combination in patients with advanced solid malignancies

Our objective was to evaluate the role of amifostine as a cytoprotector in patients with solid tumors receiving the myelosuppressive regimen of gemcitabine/cisplatin combination. Patients with advanced solid tumors were randomized to gemcitabine-amifostine-cisplatin (GAP) or gemcitabine-cisplatin (GP) in Cycle 1 (C1) and then were crossed over to the other treatment in Cycle 2 (C2). Amifostine at 740 mg/m2, followed by gemcitabine and cisplatin, were given for 2 consecutive weeks, every 4 weeks. Two GP combinations were studied: G 1000 mg/m2 and P 40 mg/m2 days 1, 8 (high dose), and G 800 mg/m2 and P 30 mg/m2 days 1, 8 (low dose). Forty patients were enrolled. Of the 19 patients treated with high-dose GP, 11 (nine patients GP in C1 and GAP in C2, two patients GAP in C1 and GP in C2) completed 2 cycles of therapy. Of the eight non-evaluable patients, five patients dropped out due to toxicity or refusal after treatment with amifostine in C1. Of the 21 patients treated with low-dose GP, 15 (eight patients GP in C1 and GAP in C2, seven patients GAP in C1 and GP in C2) were likewise evaluable. The incidence of grade 3 or 4 hematologic toxicities was similar for GP and GAP during the first 2 cycles of treatment, and there were no statistically significant differences in mean absolute neutrophil count, hemoglobin level and platelet levels between the cycles in each arm. We conclude that amifostine, at 740 mg/m2, does not lead to less myelosuppression when combined with gemcitabine/cisplatin chemotherapy regimens and may possibly contribute to subjective intolerance.

Myosin subfragment 1 and structural elements of G-actin: effects of S-1(A2) on sequences 39-52 and 61-69 in subdomain 2 of G-actin

The effect of myosin on the structure of two sequences on G-actin, a loop between residues 39 and 52 and a segment between residues 61 and 69 from the NH2-terminus, was probed by limited proteolytic digestions of G-actin in the presence of the myosin subfragment 1 isozyme S-1(A2). Under the experimental conditions of this work, no polymerization of actin was induced by S-1(A2) [Chen & Reisler (1991) Biochemistry 30, 4546-4552]. S-1(A2) did not change the rates of subtilisin and chymotryptic digestion of G-actin at loop 39-52. In contrast to this, the second protease-sensitive region on G-actin, segment 61-69, was protected strongly by S-1(A2) from tryptic cleavage. The minor if any involvement of loop 39-52 in S-1 binding was confirmed by determining the binding constants of S-1(A2) for pyrene-labeled G-actin (1.2 x 10(6) M-1), subtilisin-cleaved pyrenyl G-actin (0.3 x 10(6) M-1), and DNase I-pyrenyl G-actin complexes (0.3 x 10(6) M-1). Consistent with this, the activity of DNase I, which binds to actin loop 39-52 [Kabsch et al. (1990) Nature 347, 37-44], was inhibited almost equally well by actin in the presence and absence of S-1(A2). These results confirm the observation that DNase I and S-1(A2) bind to distinct sites on actin [Bettache et al. (1990) Biochemistry 29, 9085-9091] and demonstrate myosin-induced changes in segment 61-69 of G-actin.