Plasmodium falciparum protein kinase as a potential therapeutic target for antimalarial drugs development

Malaria is one of the most dangerous infectious diseases due to its high infection and mortality rates, especially in the tropical belt. Plasmodium falciparum (P. falciparum), the most virulent malaria parasite in humans, was recently reported to develop resistance against the final efficient antimalarial drug, artemisinin. Little is known about the resistance mechanisms, which further complicates the problem as a proper counteraction is unable to be taken. Hence, the understanding of drug mode of action and its molecular target is valuable knowledge that needs to be considered to develop the next generation of antimalarial drugs. P. falciparum protein kinase (Pf PK) is an attractive target for antimalarial chemotherapy due to its vital roles in all P. falciparum life stages. Moreover, overall structural differences and the presence of unique Pf PKs that are absent in human kinome, suggesting specific inhibition of Pf PK without affecting human cells is achievable. To date, at least 86 eukaryotic protein kinases have been identified in P. falciparum kinome, by which less than 40 were validated as potential targets at the erythrocytes stage. In this review, recent progress of the furthest validated Pf PKs; Pf Nek-1, Pf CDPK1, Pf CDPK4, Pf PKG, and Pf CLK-3 will be briefly discussed.

Ablation of vimentin results in defective steroidogenesis

In steroidogenic tissues, cholesterol must be transported to the inner mitochondrial membrane to be converted to pregnenolone as the first step of steroidogenesis. Whereas steroidogenic acute regulatory protein has been shown to be responsible for the transport of cholesterol from the outer to the inner mitochondrial membrane, the process of how cholesterol moves to mitochondria from the cytoplasm is not clearly defined. The involvement of the cytoskeleton has been suggested; however, no specific mechanism has been confirmed. In this paper, using genetic ablation of an intermediate filament protein in mice, we present data demonstrating a marked defect in adrenal and ovarian steroidogenesis in the absence of vimentin. Cosyntropin-stimulated corticosterone production is decreased 35 and 50% in male and female Vimentin null (Vim(-/-)) mice, respectively, whereas progesterone production is decreased 70% in female Vim(-/-) mice after pregnant mare's serum gonadotropin and human chorionic gonadotropin stimulation, but no abnormalities in human chorionic gonadotropin-stimulated testosterone production is observed in male Vim(-/-) mice. These defects in steroid production are also seen in isolated adrenal and granulosa cells in vitro. Further studies show a defect in the movement of cholesterol from the cytosol to mitochondria in Vim(-/-) cells. Because the mobilization of cholesterol from lipid droplets and its transport to mitochondria is a preferred pathway for the initiation of steroid production in the adrenal and ovary but not the testis and vimentin is a droplet-associated protein, our results suggest that vimentin is involved in the movement of cholesterol from its storage in lipid droplets to mitochondria for steroidogenesis.

Function preservation with multimodality treatment in locally advanced oral tongue cancer

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Background: Total or near total glossectomy with postoperative radiation is a standard treatment option for locally advanced squamous cell carcinoma oral tongue (LASCCOT). However, the procedure is controversial due to dismal cure rates and major functional deficits that impact on speech, deglutition and quality of life. We evaluated function preservation and survival outcome in LASCCOT treated with induction chemotherapy, limited surgery, and postoperative radiation/chemoradiation. Methods: We retrospectively identified 15 patients with LASCCOT treated with induction chemotherapy, limited surgery and postoperative radiation/chemoradiation at our institution between 04/07 - 04–08. M67%:F33% median age 50 years. Pretreatment AJCC stage as assessed on MRI was T2N+ (tumour crossing midline) 13%, T3N0 20%, T3N+ 47%, and T4N+ 20%. Prior to surgery induction chemotherapy, consisting of cisplatin 75 mg/m2 day 1 and gemcitabine 1 mg/m2 day 1 and 8 every three weeks for 2 cycles was given. Four to six weeks following second cycle of chemotherapy local excision of residual primary tumor with ipsilateral modified neck dissection was performed. Postoperative radiation dose was 60Gy/30 fractions. Post therapy pathological stage was ypT0N0 20%, ypT1N0 20%, ypT1N+ 40%, ypT2N+ 13%, and ypT3N+ 7%. Patients with ypN+ disease received concomitant 3 weekly cisplatin 75 mg/m2 with radiation. Results: Overall and disease free survival at 20 months was 60%. Twelve patients (80%) are alive and 3 patients (20%) have died of disease at 9, 14 and 14 months (locoregional failure 1 and distant metastasis 2 patients). In patients alive without disease assessment of deglutition and speech at the time of last follow up showed all patients on full oral diet with spontaneous intelligible speech. Conclusions: Multimodality treatment with induction chemotherapy, limited surgery and post operative radiation/chemoradiation may allow selected LASCCOT patients to avoid morbid surgery and preserve tongue function without compromising survival. This approach merits further investigation in clinical trials.

No significant financial relationships to disclose.

Primary squamous cell carcinoma of the oral cavity at presentation in Pakistan

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Background: Squamous cell carcinoma of oral cavity (SCCOC) is characterized by marked geographical differences in frequency and site distribution. Pakistan is situated within the high risk zone on the global oral cancer map. However, no reliable data exists on oral cancer in this area. Our aim was to determine clinicopathological features and patterns at presentation of primary SCCOC in a comprehensive cancer centre in Pakistan. Methods: Demographic, risk factors, pathological and AJCC staging data for SCCOC treated at Shaukat Khanum Memorial Hospital for the period November 2003-October 2008 were obtained from the head and neck unit database. Results: The database identified 666 patients with biopsy proven primary SCCOC. Mean age was 53 years (range 12 - 90 years). Male (428): Female (238) ratio was M64%:F36%. The occurrence of major risk factors for oral cancer specifically smoking, betel quid chewing, naswar (smokeless tobacco) and alcohol use in males (428) was 45% (193), 28% (118), 29% (126), 3% (13), and in females (238) was 8% (20), 29% (68), 13% (30), 0% (0), respectively. Thirty-eight percent (411/666) had no association with tobacco, betel quid or alcohol use. Subsite within oral cavity; anterior tongue 41.1% (274), buccal mucosa 26.6% (177), lower gingival and alveolus 19.5% (130), upper gingival and alveolus 4.1% (27), lips 3.6% (24), retromolar trigone 2.9% (19), hard palate 1.7% (11), and floor mouth 0.6 (4). Broder's/World Health Organization histological grade; grade I 52% (334), grade II 34% (226), grade III 7% (49), and unknown 5% (36). According to AJCC 2002 system 0.2% (1), 10.8% (72), 12.2% (81), 13.2% (88), and 63.7% (420) had stage 0, I, II, III, and IV, respectively. Conclusions: Approximately 80% of patients with primary SCCOC present with stage III or IV disease with anterior tongue as the most common subsite in our hospital. While tobacco and betel quid chewing can be attributed to development of SCCOC in a significant proportion of patients, nearly 38% are unlinked to typical risks factors suggesting other environmental and genetic agents as etiological factors in this region.

No significant financial relationships to disclose.

Trimodality treatment (TMT) for locally advanced esophageal cancer in Pakistan; Analysis of prognostic factors influencing survival

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Background: The prognosis of patients with locally advanced esophageal cancer is poor. TMT for locally advanced esophageal cancer is being utilized with increasing frequency. In this study, we investigate the prognostic factors influencing survival in patients with locally advanced esophageal cancer following TMT. Methods: The study included 22 patients with esophageal carcinoma treated between January 2003 and December 2005 at Shaukat Khanum Memorial Hospital and Research Centre. Median age was 49 years (range 26 - 68). There were 15 (68%) males and 7 (32%) females. All patients had EGD with biopsy and CT chest. Twelve (54.5%) had squamous cell carcinoma and 10 (45.5%) patients had adenocarcinoma. Five patients (23%) had tumour in the middle third and 17 (77%) had lower/gastroesophageal lesions. Preoperative radiation consisted of 50.4 Gy / 28 fractions with concomitant chemotherapy day 1 and 29 (Cisplatin 75 mg/m2 day 1 and infusional 5FU 1000 mg/m2 day 1–5). Esophagectomy was done at 6 - 12 weeks following chemoradiation. The pathologic down-staging was evaluated by the 5-score tumor regression grade (TRG) of Mandard. Results: Post TMT pathologic TNM stage was; Stage 0 in 8 pts (36%), stage II in 5 pts (23%) and stage III in 9 pts (41%). 13 (59%) pts had R0 and 9 (41%) pts had R1 resection. The 4-year disease free survival was 29% with a median survival of 19 months. The number of patients with TRG score 1, 2, 3, 4 and 5 were 7 (32%), 4 (18%), 5 (23%), 2 (9%) and 4 (18%) respectively. Tumor regression grade 1–2 (p=.0016) and negative circumferential margins >2 mm (p=.0019) had a positive influence on DFS. Age (< 50 vs ≥ 50 years), sex, hemoglobin at presentation (≤ 12 vs > 12 gm/dl), tumor site (middle vs lower/GE junction), pathological nodal status (node positive vs node negative) and histological subtype (squamous cell vs adenocarcinoma) did not influence survival (p= 0.92, p= 0.82, p= 0.69, p= 0.79, p= 0.41 and p= 0.32 respectively). Conclusions: TMT results in prolonged disease free survival in patients with complete response or microscopic residual foci (TRG 1–2). Positive or circumferential margins <2mm is associated with poor prognosis.

No significant financial relationships to disclose.

Cisplatin plus gemcitabine (GC) as induction chemotherapy in locally advanced head and neck cancer (HANC)

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Background: Cisplatin/infusional 5-fluorouracil chemotherapy is routinely administered as standard induction chemotherapy in advanced HANC. However, the optimum treatment remains to be defined. Gemcitabine is an active agent in HANC and few studies have evaluated induction GC in HANC. We have explored the activity and toxicity of GC as induction treatment in HANC and report the results. Methods: From August 2005 to September 2006, 55 patients with locally advanced HANC had induction chemotherapy with GC at Shaukat Khanum Memorial Cancer Hospital and Research Centre. We reviewed the medical records and prospectively collected data to determine activity and toxicity of induction GC. M:F ratio was 64%:36% with a median age of 50 years (range 19–80). All patients had histologically confirmed squamous cell carcinoma. The site of disease was nasopharynx, paranasal sinuses, oral cavity, oropharynx, larynx and hyopharynx in 4% (2), 11% (6), 51% (21), 2% (1), 11% (6) and 22% (11) respectively. According to AJCC staging 7% (4) had stage III and 93% (51) had stage IVa/IVb disease (T3N0 7%, T3N+ 2%, T4N0 38% and T4N+ 53%). Induction chemotherapy consisted of 2 cycles of cisplatin 75 mg/m2 day 1 and gemcitabine 1000 mg/m2 day 1 and 8 with treatment repeated three weekly. Fifty-three (94%) patients received 2 cycles as planned. Toxicity was scored after each cycle according to the NCI.CTC criteria. Response was assessed following completion of induction chemotherapy by clinical examination/MRI scan. Results: All patients were available for assessment of toxicity and response. A total of 111 cycles were delivered. The response rates are: complete 24% (13), partial 62% (34), no response 7% (4) and progression 7% (4). The overall response rate was 86% (complete 24%, partial 62%). No treatment related deaths occurred. Haematological G3/G4 toxicity included neutropenia (13%/7%) and thrombocytopenia (5%/0%). The non-haematological toxicity observed (nausea, vomiting and diarrhoea) was only G1/G2. Conclusions: GC is well tolerated with low toxicity and high anti tumour activity as neoadjuvant chemotherapy treatment in squamous cell head and neck cancer. Combination GC arm should be included in future trials.

No significant financial relationships to disclose.

Induction chemotherapy with gemcitabine and cisplatin in paranasal sinus tumours

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Background: There is no standard treatment for locally advanced carcinoma of paranasal sinuses. Induction chemotherapy is frequently used to down stage the disease. Surgery, radiotherapy and chemoradiation are all in use to treat the primary following neoadjuvant chemotherapy treatment. Cisplatin and gemcitabine are active agents in head and neck cancers. We evaluated the response of induction chemotherapy with cisplatin and gemcitabine in carcinoma of the paranasal sinuses. Methods: Between August 2005–November 2005, 5 patients with locally advanced carcinoma paranasal sinuses received induction chemotherapy at Shaukat Khanum Cancer Hospital and Research Centre. There were three males and two females, 19 to 65 (median 45) years of age. Three patients had maxillary and 2 patients had ethmoid sinus tumors. Four patients had Stage IVa and 1 patient had Stage IVb disease. All patients had biopsy proven carcinoma. Histologically the tumour was adenocarcinoma in 1 patient and squamous cell carcinoma in 4 patients. Four patients received 2 cycles and 1 patient received 1 cycle of cisplatin 75 mg/m2 day 1 and gemcitabine 1000 mg/m2 day 1 and 8 (repeat day 22) before radical treatment. Response was assessed in all patients with pre and post induction chemotherapy with CT or MRI scan. Results: Overall response rate was 60%. Complete response was seen in one patient and over 50% tumor regression in 2 patients. Disease remained unchanged (no response) in 1 patient. One patient progressed following one cycle and did not receive the second cycle of chemotherapy treatment. The treatment was well tolerated and no grade III or IV toxicity was seen. Conclusions: The combination of gemcitabine and cisplatin in this schedule has low toxicity and significant activity in patients with locally advanced paranasal sinus tumors and is worthy of further study.

No significant financial relationships to disclose.

A complication of a long-standing solitary lung cyst

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