A multidisciplinary treatment strategy that includes high-dose chemotherapy for metastatic retinoblastoma without CNS involvement

Management of Extraocular Retinoblastoma: ICMR Consensus Guidelines

Retinoblastoma (RB) is the most common intraocular malignancy of childhood. Advanced stage presentation of RB is common in low middle-income countries (LMICs) due to lack of awareness, social taboos associated with enucleation, seeking alternative conservative treatment options, and poor accessibility to health care. Over the last few decades, there have been significant advancements in the management of extraocular RB (EORB) which have improved outcomes and helped in minimizing treatment-related toxicities. The incorporation of multimodality approaches including chemotherapy, surgery, and radiotherapy (RT) has shown promising results; however, prognosis remains poor especially in LMICs. In this article, authors have discussed the ICMR consensus guidelines on the management of EORB, including metastatic RB.

Lack of complete response pretransplant is not associated with inferior overall survival for stage 4a metastatic retinoblastoma

BACKGROUND

Stage 4a metastatic retinoblastoma (RB) is curable with intensive multimodality therapy including myeloablative chemotherapy with autologous stem cell transplant (HDC-ASCT) and involved field radiation therapy (IFRT). To our knowledge, no data exist on the impact of (a) pre-ASCT disease status, and (b) IFRT to sites of metastatic disease post ASCT on survival.

PROCEDURE

We retrospectively reviewed patients with stage 4a metastatic RB who underwent induction chemotherapy followed by HDC-ASCT, with or without IFRT, to residual tumor sites at Memorial Sloan Kettering Cancer Center (MSKCC) (n = 24).

RESULTS

The degree of postinduction response prior to ASCT did not affect outcome, with 5-year overall survival (OS) of 68% and 86% in patients who achieved complete response (CR) and very good partial response (VGPR)/partial response (PR) prior to ASCT, respectively. IFRT administered post ASCT in patients with possible residual bony metastatic disease increases the likelihood of developing osteosarcoma in the radiation field.

CONCLUSION

OS for patients with stage 4a metastatic RB treated with ASCT with VGPR or PR to pretransplant chemotherapy was not significantly different from patients with CR. In addition, IFRT does not seem to be required for bony disease control and increased the likelihood of developing osteosarcoma.

Intensive Multimodality Therapy for Extraocular Retinoblastoma: A Children's Oncology Group Trial (ARET0321)

PURPOSE

Metastatic retinoblastoma has a poor prognosis when treated with conventional chemotherapy and radiation therapy (RT). Intensified therapy may improve the outcome.

METHODS

A prospective, international trial enrolled patients with extraocular retinoblastoma. Patients with stage II or III (locoregional) retinoblastoma received four cycles of chemotherapy, followed by involved field RT (45 Gy). Patients with stage IVa or IVb (metastatic or trilateral) retinoblastoma also received four cycles of chemotherapy and those with ≥ partial response then received one cycle of high-dose carboplatin, thiotepa, and etoposide with autologous hematopoietic stem-cell support. Patients with stage IVa or IVb with residual tumor postchemotherapy received RT. The proportion of patients who achieved event-free survival would be reported and compared with historical controls separately for each of the three groups of patients.

RESULTS

Fifty-seven eligible patients were included in the analyses. Event-free survival at 1 year was 88.1% (90% CI, 66.6 to 96.2) for stage II-III, 82.6% (90% CI, 61.0 to 92.9) for stage IVa, and 28.3% (90% CI, 12.7 to 46.2) for stage IVb/trilateral. Toxicity was significant as expected and included two therapy-related deaths.

CONCLUSION

Intensive multimodality therapy is highly effective for patients with regional extraocular retinoblastoma and stage IVa metastatic retinoblastoma. Although the study met its aim for stage IVb, more effective therapy is still required for patients with CNS involvement (ClinicalTrials.gov identifier: NCT00554788).

Stem-Cell Therapy Following High-Dose Chemotherapy in Advanced Retinoblastoma: A Systematic Review

PURPOSE

To analyze the risk and benefit of high-dose chemotherapy followed by stem cell transplantation (HDCT-SCT) treatment in patients with advanced retinoblastoma.

DESIGN

Systematic review.

METHODS

A comprehensive literature search from 4 online databases, including PubMed, Scopus, EBSCO, and Cochrane was done for original studies evaluating the use of HDCT followed by SCT in the treatment of patients with advanced retinoblastoma. The last search was performed on April 15, 2020.

RESULTS

A total of 35 studies consisting of 160 patients were considered suitable for inclusion. After HDCT-SCT treatment, 108/160 (67.5%) patients were alive with no evidence of disease at the last follow-up. The incidence of secondary malignancy in our data was also relatively low, which was 16/160 (10%) patients. The side effects were mainly hematological and gastrointestinal toxicities. The prognosis for metastatic cases especially the one to the central nervous system (CNS) remains poor, as shown in our data that 22 of 44 (50%) patients died due to the evidence of disease, and 12 of 44 (27%) patients acquired CNS relapse and died.

CONCLUSIONS

HDCT-SCT is a promising treatment option in patients with advanced retinoblastoma. The use of HDCT-SCT in CNS metastases needs to be carefully considered, possibly by adding thiotepa or topotecan to improve tumor control. Further randomized clinical trials are needed to draw firm conclusion regarding its safety and efficacy.

Successful Treatment of Relapsed Isolated Extraocular Retinoblastoma in the Right Fibula With High-dose Chemotherapy and Autologous Stem Cell Transplantation

Literature on high-dose chemotherapy followed by autologous stem cell rescue in relapsed retinoblastoma is limited to <150 cases reported so far. We present our experience and the challenges faced in the management of a 7-year-old boy with relapsed isolated extraocular retinoblastoma in the right fibula who received salvage chemotherapy followed by high-dose chemotherapy and autologous stem cell rescue. Electrolyte disturbances, renal tubulopathy, and seizures were the most significant transplant-related morbidity. The child is now 3 years postautograft in remission. Monitoring for second malignant neoplasm and late side effects remain the main challenges in the years to come.

An extremely rare case of metastatic retinoblastoma of parotids presenting as a massive swelling in a child

Retinoblastoma (Rb) is a common childhood malignancy but bilateral Rb with metastasis to parotids is very uncommon. To the best of our knowledge, bilateral Rb metastasizing to parotids is very rare and this is the fifth such case reported in world literature till date in a 2-year-old male child who underwent exenteration of left eye for bilateral Rb and later developed recurrent metastasis to left parotid requiring parotidectomy. A year later he presented again with swelling left parotid region extending from occipital region reaching upto left anterior chest wall with intra-cranial extension on magnetic resonance imaging. Histopathological examination of the parotid swelling and immunohistochemistry showed metastasis from Rb. He was treated with chemotherapy followed by radiotherapy to local site and brain to which he responded well. Presently on regular follow up without any signs of locoregional and distal metastasis. Till date different types of primary parotid tumors have been reported in literature but a metastatic parotid tumor is extremely rare and therefore this case is being reported to highlight the extreme rarity, the diagnostic and therapeutic challenges, the highly aggressive nature and overall dismal prognosis of this disease entity.

High-dose chemotherapy for high-risk retinoblastoma: clinical course and outcome of 14 cases in the National Cancer Center, Japan

The prognosis of high-risk retinoblastoma (RB) with extraocular disease, relapse, or invasion of the cut end of the optic nerve is extremely poor. Following the discontinuation of thiotepa production in Japan, BU- and melphalan (Mel)-based regimens have been used, followed by the standard treatment for neuroblastoma. This study retrospectively analyzed 14 high-risk RB patients who underwent high-dose chemotherapy (HDC) and hematopoietic SCT; 8 received a BU/Mel conditioning regimen and 6 received other regimens. The disease status at HDC was relapse in 8 patients and extraocular involvement in 5. All patients received peripheral blood stem cell infusion >1.5 × 10(6)/kg. Engraftment occurred within a median of 11 days (BU/Mel: 10-13, others: 9-13). Primary toxicities included mucositis (⩾grade 3) in 9 patients (4 with BU/Mel, 5 with others). Veno-occlusive disease (VOD) occurred in two 1-year-old patients in the BU/Mel group. There were no treatment-related deaths. Of 4 (2 with BU/Mel, 2 with others) patients with central nervous system (CNS) relapse after HDC, 3 died. In conclusion, the BU/Mel regimen may be feasible for high-risk RB under careful monitoring for VOD, particularly in younger patients. CNS relapse associated with a lethal prognosis occurred after all regimens; therefore, further evaluation of HDC efficacy for high-risk RB is required.

Autologous hematopoietic stem cell transplantation for pediatric solid tumors

While advances in the treatment of pediatric cancers have increased cure rates, children with metastatic or recurrent solid tumors have a dismal prognosis despite initial transient responses to therapy. Autologous hematopoietic stem cell transplantation takes advantage of the steep dose-response relationship observed with many chemotherapeutic agents. While clearly demonstrated to improve outcomes in patients with metastatic neuroblastoma, autologous hematopoietic stem cell transplantation is also frequently used to treat patients with other high-risk diseases such as Ewing sarcoma, osteosarcoma, rhabdomyosarcoma, Wilms' tumor, retinoblastoma, germ cell tumors, lymphomas and brain tumors. Most published experience consists of retrospective, single-arm studies; randomized clinical trials are lacking, due in part to the rarity of pediatric cancers treatable by autologous hematopoietic stem cell transplantation. These published literature demonstrate that autologous hematopoietic stem cell transplantation results in most cases in equivalent or superior outcomes when compared with conventional therapies. However, patient heterogeneity, patient selection, graft characteristics and processing and the varied conditioning regimens are additional factors to consider. Since the inception of autologous hematopoietic stem cell transplantation, regimen-related toxicity has markedly decreased and the vast majority of treatment failures are now due to disease recurrence. Prospective clinical trials are needed to identify specific high-risk patient populations, with randomization (when possible) to compare outcomes of patients undergoing autologous hematopoietic stem cell transplantation with those receiving standard therapy. In addition, investigators need to better define the role of autologous hematopoietic stem cell transplantation in these solid tumors, particularly in combination with other therapeutic modalities such as immunotherapy and novel cell processing methodologies.

High-dose chemotherapy followed by stem cell transplantation in the management of retinoblastoma: a systematic review

BACKGROUND AND OBJECTIVES

In recent years, there has been an increasing role for stem cell transplantation in the management of retinoblastoma. The aim of this study was to systematically review the role high-dose chemotherapy followed by stem cell transplantation in the treatment of patients with metastatic or relapsed, trilateral or bilateral advanced retinoblastoma, and in patients with tumor at the surgical margin of the optic nerve and/or extrascleral extension.

DESIGN

Systematic literature review.

METHODS

We performed an extensive PubMed database search on 25 February 2012 for studies describing the use of high-dose chemotherapy followed by stem cell transplantation in the management of patients with retinoblastoma.

RESULTS

We located 15 studies that met the inclusion criteria and that included 101 patients. Following treatment for metastatic and relapsed disease, 44 of 77 patients (57.1%) were alive with no evidence of disease at the time of follow-up. However, a higher rate of local relapse developed in patients with CNS metastases (73.1%), which dropped to 47.1% in patients who received thiotepa. In patients with trilateral or bilateral advanced retinoblastoma, 5 of 7 (71.4%) with reported outcome data were alive with no evidence of disease at the time of follow-up. In patients with tumor at the surgical margin of the optic nerve and/or extrascleral extension, 6 of 7 patients (85.7%) were alive with no evidence of disease at the time of follow-up.

CONCLUSIONS

Durable tumor control is possible in patients with non-CNS metastases, trilateral or bilateral advanced retinoblastoma, and in patients with tumor at the surgical margin of the optic nerve and/or extrascleral extension. Patients with CNS metastases require thiotepa to improve tumor control.

Current therapy and recent advances in the management of retinoblastoma

Retinoblastoma is the most common intraocular malignancy in children. The survival of retinoblastoma patients and visual outcome has improved dramatically in the developed world. This can be attributed to early tumor recognition and advances in the management of retinoblastoma. Chemoreduction followed by adjuvant consolidative treatment has replaced external beam radiotherapy as the primary modality of treatment for intraocular retinoblastoma. Further, histopathological high-risk factors have been identified in enucleated eyes, allowing use of prophylactic chemotherapy to take care of possible micrometastasis. The survival in case of extraocular retinoblastoma is still low, and the reported survival rate ranges between 50% and 70%. In developing countries, the overall survival of retinoblastoma patients remains low, primarily due to a delayed presentation, resulting in larger proportions of extraocular disease compared with the developed world, where majority of the disease is intraocular. Greater efforts need to be directed toward early tumor recognition in order to improve the survival of retinoblastoma patients in the developing world. In this article, we provide an overview of the current clinical management of retinoblastoma.

High-dose chemotherapy with autologous hematopoietic stem cell rescue for stage 4B retinoblastoma

BACKGROUND

Stage 4b retinoblastoma (central nervous system metastatic disease) has been lethal in virtually all cases reported. Here we describe a series of eight patients treated with intensive chemotherapy, defined as the intention to include high-dose chemotherapy with autologous hematopoietic stem cell rescue.

PROCEDURE

Induction chemotherapy included cyclophosphamide and/or carboplatin with a topoisomerase inhibitor. High-dose chemotherapy regimens were carboplatin and thiotepa with or without etoposide (n = 3) or carboplatin, etoposide, and cyclophosphamide (n = 2).

RESULTS

Seven patients had leptomeningeal disease and one patient had only direct extension to the CNS via the optic nerve. Three patients had stage 4b disease at the time of original diagnosis of the intra-ocular retinoblastoma; five had later onset at a median of 12 months (range 3-69 months). One patient died of toxicity (septicemia and multi-organ system failure) during induction and two had disease progression prior to high-dose chemotherapy. Five patients received high-dose chemotherapy at a median of 6 months (range 4-6) post-diagnosis of stage 4b disease. Two patients survive event-free at 40 and 101 months; one was irradiated following recovery from the high-dose chemotherapy.

CONCLUSIONS

Intensive multimodality therapy may be beneficial for some patients with stage 4b retinoblastoma. Longer follow-up will determine whether it has been curative.

Intensive multimodality therapy for patients with stage 4a metastatic retinoblastoma

BACKGROUND

We previously reported promising pilot results treating patients with stage 4a metastatic retinoblastoma with combined intensive conventional chemotherapy, high-dose chemotherapy with autologous hematopoietic stem cell rescue, and radiation therapy and now present an expanded and updated series.

PROCEDURE

Fifteen patients with bone marrow (n = 14), bone (n = 10), orbit (n = 9), and/or liver (n = 4) disease were treated. Induction chemotherapy usually consisted of vincristine, cyclophosphamide, cisplatin, and etoposide. The high-dose chemotherapy regimen included carboplatin and thiotepa alone (n = 1) or with etoposide (n = 5) or topotecan (n = 7).

RESULTS

Bone marrow cleared at first post-initiation of chemotherapy examination in all patients and stem cells were harvested after a median of 3.5 cycles of chemotherapy (range 3-6 cycles). Two patients progressed prior to high-dose chemotherapy and died. Thirteen received high-dose chemotherapy at a median of 6 months post-diagnosis of metastases (range 4-8 months). Ten are retinoblastoma-free in first remission at a median follow-up of 103 months (range 34-202 months) while three recurred (two in the CNS, one in the mandible) 14-20 months post-diagnosis of metastases. Retinoblastoma-free and event-free survival at 5 years are 67% (95% confidence interval 38-85%) and 59% (95% confidence interval 31-79%). Six of the 10 survivors received radiation therapy. Three patients developed secondary osteosarcoma 14, 4, and 9 years after diagnosis of metastatic disease.

CONCLUSIONS

Intensive multimodality therapy including high-dose chemotherapy with autologous hematopoietic stem cell rescue was curative for the majority of patients with stage 4a metastatic retinoblastoma treated. The contribution of external beam radiation therapy is unclear.

Trilateral retinoblastoma: potentially curable with intensive chemotherapy

BACKGROUND

Trilateral retinoblastoma has been lethal in virtually all cases previously reported. We describe a series of 13 patients treated with intensive chemotherapy, defined as the intention to include high-dose chemotherapy with autologous hematopoietic stem cell rescue.

PROCEDURE

Induction chemotherapy generally included vincristine, cisplatin or carboplatin, cyclophosphamide, and etoposide. Hematopoietic stem cells typically were harvested after the first or second cycle of induction chemotherapy, usually from peripheral blood. High-dose chemotherapy regimens were thiotepa-based (n = 7) or melphalan and cyclophosphamide (n = 3).

RESULTS

Trilateral sites were pineal (n = 11) and suprasellar (n = 2); 7 patients had localized (M-0) disease and six had leptomeningeal dissemination (M-1+). Five patients had trilateral retinoblastoma at original diagnosis of intra-ocular retinoblastoma; eight later developed trilateral disease at a median of 35 months (range 3-60 months) following diagnosis of intra-ocular retinoblastoma. One patient died of toxicity (septicemia and multi-organ system failure) during induction and three developed disease progression prior to high-dose chemotherapy. Nine patients received high-dose chemotherapy at a median of 5 months (range 4-9) post-diagnosis of trilateral disease. Five patients survive event-free at a median of 77 months (range 36-104 months) and never received external beam radiation therapy. Four of seven patients with M-0 disease survive event-free versus only one of six patients with M-1+ disease.

CONCLUSIONS

Intensive chemotherapy is potentially curative for some patients with trilateral retinoblastoma, especially those with M-0 disease.

Clinical results of chemotherapy based treatment in retinoblastoma patients: a single center experience

PURPOSE

Retinoblastoma is the most common intraocular malignancy in children. Since the 1990s, chemotherapy was indicated for intraocular disease to reduce the frequency of enucleation and spare the complications associated with external beam radiation. In this study, we analyzed treatment results of retinoblastoma in our institute.

MATERIALS AND METHODS

Datas from children diagnosed with retinoblastoma and treated at Seoul National University Children's Hospital between 1986 and 2008 were analyzed retrospectively. We utilized cyclophosphamide, vincristine, adriamycin, and methotrexate (CVAM) for OPD-based adjuvant chemotherapy. From 1990, primary chemotherapy was administered to patients with intraocular disease for eyeball-saving and patients received a combination of etoposide, vincristine, cisplatin (or ifosfamide) as a moderately intensive regimen, or a combination of cisplatin, doxorubicin, etoposide, and cycophosphamide (CDEC) as a highly intensive regimen.

RESULTS

One hundred eighteen children were analyzed. There were 68 unilateral and 50 bilateral diseases. The median age at diagnosis was 1 year and Reese-Ellsworth stage V was the most common stage at the time of diagnosis. All patients were treated by chemotherapy-based multimodality methods, and primary chemotherapy was administered to 80 patients. The 10-year overall and event-free survival rate of all patients were 93.9% and 91.6%, respectively. Two patients who died were in the CDEC regimen group, but there was no significant statistical difference in survival rates by chemotherapy regimens. Fifty-six of 114 eyeballs were saved after primary chemotherapy-based treatment, and the eyeball-saving rate was 49.1%. Six patients relapsed after enucleation and 2 patients were treated successfully after autologous PBSCT. Osteosarcoma occurred in 2 patients as a secondary malignancy, and facial asymmetry after radiotherapy was the most common long-term sequelae.

CONCLUSIONS

In this study, the overall and event-free survival rates of retinoblastoma were satisfactory and eye-saving was possible with primary chemotherapy. Development of new chemotherapeutic regimens and a team approach are necessary to improve the eyeball-saving rate.

Treatment of retinoblastoma: Current status and future perspectives

Treatment of retinoblastoma must be individualized. Most patients with unilateral, non-metastatic retinoblastoma can be cured with enucleation alone. In patients with histologic risk factors, adjuvant chemotherapy is recommended, with the addition of orbital radiation for patients with trans-scleral involvement or tumor present at the level of the cut end of the optic nerve. Patients with metastases require intensive chemotherapy and consolidation with autologous hematopoietic stem cell rescue. Patients with bilateral or multifocal disease represent a major challenge. Cure of the disease is the first priority, but the therapeutic approach also has to consider eye and vision preservation. The approach is conservative, and only eyes with very advanced disease are enucleated upfront. Patients are treated with chemotherapy and intensive focal treatments, with the aim of delaying or avoiding radiation therapy and enucleation. For patients with early intraocular stage (Reese-Ellsworth groups I-III and International Groups A-B), the two-drug combination of vincristine and carboplatin is recommended. Patients with more advanced intraocular disease (Reese-Ellsworth groups IV-V and International Groups C-D) require more intensive chemotherapy. Standard of care for these patients incorporates etoposide into the regimen. Effective agents with good intraocular penetration, such as topotecan, are being investigated. Because most failures are secondary to progression of the vitreous seeds, subconjunctival carboplatin is added in cases with poor response of the vitreous tumors. Patients must be monitored very closely, with examinations under anesthesia every 4 to 6 weeks, and focal treatments are applied during the procedure. These include cryotherapy for small anterior tumors, thermotherapy and laser photocoagulation for small posterior tumors, and brachytherapy for larger tumors. New treatment approaches under development include the refinement of periocular chemotherapy administration using slow-release devices, the use of suicide gene therapy with local delivery of the herpes simplex thyrosine kinase gene (followed by systemic administration of ganciclovir), and the development of small-molecule inhibitors of the MDMX-p53 interaction.

Tandem high-dose chemotherapy and autologous stem cell rescue in children with bilateral advanced retinoblastoma

Although external-beam radiation therapy (EBRT) has been an effective treatment modality in patients with bilateral advanced retinoblastoma, it significantly increases the risk of second malignancies and facial deformities. This study aimed to evaluate the efficacy of tandem high-dose chemotherapy and autologous stem cell rescue (HDCT/ASCR) for treatment, instead of EBRT, in children with bilateral advanced retinoblastoma. Fourteen patients with bilateral retinoblastoma received chemotherapy, and local therapy was provided whenever possible. When at least one functional eye could not be saved by chemoreduction and local therapy, tandem HDCT/ASCR was provided to avoid EBRT. As a result, nine patients received tandem HDCT/ASCR. The toxicities were tolerable and there was no TRM. All nine patients who received tandem HDCT/ASCR had at least one functional eye without EBRT, and in two patients, both eyes were saved. No second malignancy has developed to date. HDCT/ASCR might be an effective treatment for bilateral advanced retinoblastoma, especially in cases in which at least one functional eye could not be preserved with chemoreduction and local therapy alone, and where EBRT was unavoidable. Long-term follow-up and further studies are needed to evaluate the efficacy and toxicity of HDCT/ASCR as an alternative treatment to EBRT.

Treatment of invasive retinoblastoma in a murine model using an oncolytic picornavirus

Retinoblastoma, the most common intraocular malignancy of childhood, metastasizes by initial invasion of the choroid and the optic nerve. There is no effective treatment for metastatic retinoblastoma, especially when the central nervous system (CNS) is involved, and prevention of this complication is a treatment priority. Seneca Valley Virus (SVV-001) is a conditionally replication-competent picornavirus that is not pathogenic to normal human cells but can kill human retinoblastoma cells in vitro with an IC(50) of <1 viral particle (vp) per cell. A xenograft murine model of metastatic retinoblastoma was used to examine the therapeutic potential of SVV-001. Histopathologic analysis of ocular and brain tissues after a single tail vein injection of SVV-001 (1 x 10(13) vp/kg) showed effective treatment of choroid and ocular nerve tumor invasion (1 of 20 animals with invasive disease in the treated group versus 7 of 20 animals with invasive disease in the control group; P = 0.017) and prevention of CNS metastasis (0 of 20 animals with CNS metastatic disease in the treated group versus 4 of 20 animals with CNS disease in the control group; P = 0.036). There were no observed adverse events due to the virus in any of the treated animals. SVV-001 may be effective as a treatment of locally invasive and metastatic retinoblastoma.

Trilateral retinoblastoma with suprasellar tumor and associated pineal cyst

Trilateral retinoblastoma (TRb) is a well-known syndrome associating hereditary retinoblastoma (Rb) with an intracranial neuroblastic tumor arising usually in the pineal region, rarely at the suprasellar or parasellar site. It develops in most cases after diagnosis of Rb. The outcome is usually fatal because of secondary spinal dissemination. Pineal cysts have recently been reported as a benign variant of TRb. We report the unusual presentation of a TRb in a 12-month-old boy with extensive bilateral Rb, a voluminous suprasellar tumor, pineal cyst, and leptomeningeal disease. The special features of this "quadrilateral" Rb are discussed.

Concise review: recent advances on the significance of stem cells in tissue regeneration and cancer therapies

In this study, we report on recent advances on the functions of embryonic, fetal, and adult stem cell progenitors for tissue regeneration and cancer therapies. We describe new procedures for derivation and maturation of these stem cells into the tissue-specific cell progenitors. The localization of the adult stem cells and their niches, as well as their implication in the tissue repair after injuries and during cancer progression, are also described. The emphasis is on the interactions among certain developmental signaling factors, such as hormones, epidermal growth factor, hedgehog, Wnt/beta-catenin, and Notch. These factors and their pathways are involved in the stringent regulation of the self-renewal and/or differentiation of adult stem cells. Novel strategies for the treatment of both diverse degenerating disorders, by cell replacement, and some metastatic cancer types, by molecular targeting multiple tumorigenic signaling elements in cancer progenitor cells, are also illustrated.