Pathologic complete response with radiation and vismodegib in a patient with advanced basal cell carcinoma: A case report

Hedgehog signalling pathway inhibitors in the treatment of basal cell carcinoma: an updated review

Basal cell carcinoma (BCC) is the most common type of skin cancer that usually appears in sun-exposed body regions such as the head, trunk, and extremities. There are four main clinicopathological subtypes of BCC: nodular, superficial, morpheaform, and fibroepithelial. BCC's molecular basis includes inherited genetic susceptibility and somatic mutations, often induced by exposure to UV radiation. The aberrant activation of the hedgehog (Hh) signalling pathway, caused by mutations in the Hh components, plays a central role in the molecular pathogenesis of this carcinoma. This led to the development of Hh signalling pathway inhibitors as a new treatment option for patients with advanced disease. In this review, we summarise BCC's clinical presentation and histopathology and present knowledge on the most studied Hh signalling inhibitors, vismodegib and sonidegib, and other inhibitors of this signalling, such as itraconazole, patidegib, taladegib, and arsenic trioxide, in the treatment of BCC. We also present the most common Hh signalling inhibitor adverse events and their management options, which could improve patients' quality of life during treatment.

Abscopal Effects and Immunomodulation in Skin Cancer Therapy

Radiation therapy (RT) is a crucial modality in cancer treatment, functioning through direct DNA damage and immune stimulation. However, RT's effects extend beyond targeted cells, influencing neighboring cells through the bystander effect (ByE) and distant sites via the abscopal effect (AbE). The AbE, first described by Mole in 1953, encompasses biological reactions at sites distant from the irradiation field. While RT can enhance antitumor immune responses, it may also contribute to an immunosuppressive microenvironment. To address this limitation, combining RT with immune checkpoint inhibitors (ICIs) has gained renewed interest, aiming to amplify antitumor immune responses. Evidence of AbEs has been observed in various metastatic or advanced cutaneous cancers, including melanoma, basal cell carcinoma, cutaneous lymphoma, Merkel cell carcinoma, and cutaneous squamous cell carcinoma. Clinical studies suggest combining RT with ICIs targeting CTLA-4 and PD-1/PD-L1 may enhance AbE incidence in these cancers. This review primarily explores the current understanding of AbEs in skin cancers, briefly acknowledging the ByE focusing on combining RT with immunomodulation. It focuses on proposed mechanisms, preclinical and clinical evidence, challenges in clinical translation, and future directions for harnessing AbEs in managing advanced skin malignancies. Alternative modalities for inducing abscopal-like responses are also explored. While promising, challenges remain in consistently reproducing AbEs in clinical practice, necessitating further research to optimize treatment combinations, timing, and patient selection.

Sequential combination of sonic hedgehog inhibitors followed by consolidation radiotherapy in locally advanced basal cell carcinoma

BACKGROUND

Sonic hedgehog inhibitors (SHHis) are an effective treatment in locally advanced basal cell carcinoma (laBCC). However, the use of these drugs is limited by adverse events, and relapse at discontinuation in around one-half of patients. A few cases of patients treated concomitantly by radiotherapy (RT) and SHHis have been reported in the literature, suggesting that the combination results in an improved overall response. Maintaining complete response after stopping treatment is a concern, especially as resuming treatment in the case of relapse does not guarantee a new therapeutic response. The optimal combination and sequence of treatment to improve local control of laBCCs are not yet defined.

OBJECTIVES

We hypothesized that consolidation RT after complete response to SHHis could reduce the risk of relapse at discontinuation.

METHODS

We present a case series of patients with laBCCs who achieved complete response after SHHi treatment and were treated with consolidation RT. Patients were evaluated by a skin cancer board. The closure RT technique and dosage were refined by a radiotherapist.

RESULTS

Eleven patients were included. SHHis were prescribed for a median 5 months (range 4-11). Consolidation RT was performed after complete response to SHHis and discontinuation. RT was delivered at a median dose of 45 Gy (range 40.5-66) in 10 fractions (range 9-33). With a median follow-up of 23 months, all patients maintained complete clinical response. This strategy was well tolerated with no grade 3 adverse events.

CONCLUSIONS

SHHi treatment followed by consolidation RT after drug discontinuation seems effective and safe. Further studies are needed to develop a precise strategy for the management of laBCCs.

Phase II, Single-Arm Trial of Induction and Concurrent Vismodegib With Curative-Intent Radiation Therapy for Locally Advanced, Unresectable Basal Cell Carcinoma

PURPOSE

Locally advanced, unresectable basal cell carcinoma (LA BCC) can be treated with radiation therapy (RT), but locoregional control (LRC) rates are unsatisfactory. Vismodegib is a hedgehog pathway inhibitor (HPI) active in BCC that may radiosensitize BCC. We evaluated the combination of vismodegib and RT for patients with LA BCC.

METHODS

In this multicenter, single-arm, phase II study, patients with unresectable LA BCC received 12 weeks of induction vismodegib, followed by 7 weeks of concurrent vismodegib and RT. The primary end point was LRC rate at 1 year after the end of treatment. Secondary end points included objective response, progression-free survival (PFS), overall survival (OS), safety, and patient-reported quality of life (PRQOL).

RESULTS

Twenty-four patients received vismodegib; five were unable to complete 12 weeks of induction therapy. LRC was achieved in 91% (95% CI, 68 to 98) of patients at 1 year. The response rate was 63% (95% CI, 38 to 84) after induction vismodegib and 83% (95% CI, 59 to 96) after concurrent vismodegib and RT. With a median follow-up of 5.7 years, 1-year PFS and OS rates were 100% and 96%, and at 5 years PFS and OS rates were 78% and 83%, respectively. Distant metastasis or BCC-related death has not been observed. The most frequent treatment-related adverse events (AEs) were dysgeusia, fatigue, and myalgias occurring in 83%, 75%, and 75% of patients. No grade 4 to 5 treatment-related AEs occurred. PRQOL demonstrated clinically meaningful improvements in all subscales, with emotions and functioning improvements persisting for a year after the end of treatment.

CONCLUSION

In patients with unresectable LA BCC, the combination of vismodegib and RT yielded high rates of LRC and PFS and durable improvements in PRQOL.

Combined cemiplimab and radiotherapy for advanced basal cell carcinoma: A case report

Advanced basal cell carcinoma may be treated with systemic therapies such as hedgehog pathway inhibitors or programmed cell death protein 1 inhibitors, namely cemiplimab. We report a case of a 70-year-old man with a nodulo-infiltrative advanced basal cell carcinoma over the right posterior neck and scapula. The patient had a partial response to the hedgehog pathway inhibitor, vismodegib. The tumour progressed, and the patient was switched from vismodegib to radiotherapy combined with cemiplimab, which led to a significant reduction in pain, bleeding, and tumour size. A combined treatment approach with radiotherapy and cemiplimab may be beneficial for advanced basal cell carcinoma cases that progress after treatment with hedgehog pathway inhibitors.

Advanced basal cell carcinoma: What dermatologists need to know about treatment

The treatment of advanced basal cell carcinoma (BCC) often requires therapies beyond local surgical excision or radiation due to the invasiveness of the tumor. Historically, cytotoxic chemotherapy was used to treat advanced BCC, but with limited data, no standard regimens were established. The discovery of cyclopamine, a natural inhibitor in the Hedgehog pathway, led to the development of the 2 currently approved Hedgehog inhibitors, vismodegib and sonidegib. Both agents are indicated for locally advanced BCC, while vismodegib is also indicated for metastatic BCC. In patients who progress on hedgehog inhibitors or cannot tolerate hedgehog inhibitors, the programmed cell death protein 1 inhibitor cemiplimab can be used to treat locally advanced or metastatic disease. Complex cases of locally advanced or metastatic BCC may be best discussed through a multidisciplinary approach in order to determine the optimal treatment approach for the individual patient.

Hedgehog Inhibitor Induction with Addition of Concurrent Superficial Radiotherapy in Patients with Locally Advanced Basal Cell Carcinoma: A Case Series

BACKGROUND

Locally advanced basal cell cancer is a rare and challenging clinical problem. Historically, these patients were treated with aggressive surgery or radiotherapy. Most sporadic basal cell carcinomas have somatic mutations in the hedgehog pathway. Oral hedgehog inhibitors induce rapid and often complete clinical responses in locally advanced basal cell tumors. Unfortunately, these responses are usually transient. We hypothesized that treatment failure represents persistence of drug resistant cells that could be eradicated by addition of localized radiotherapy.

MATERIALS AND METHODS

We performed a retrospective review of our patients with locally advanced basal cell cancer treated with sonidegib or vismodegib induction therapy who were treated with added superficial radiotherapy at the time of maximal response.

RESULTS

Twelve patients met inclusion criteria. All patients achieved a complete response following hedgehog inhibitor therapy with addition of radiotherapy. Progression-free survival at 40 months was 89%, with a median follow-up of 40 months. Relapses occurred in only 2 of 12 patients (16.6%). Nine patients experienced grade I-II toxicity from hedgehog inhibitor induction therapy (taste changes [3], weight loss [3], muscle cramps [3]). Eight patients experienced mild radiotherapy-induced skin toxicity during concurrent therapy. No patients had to discontinue treatment.

CONCLUSION

Induction therapy with hedgehog inhibitors followed by addition of concurrent radiation therapy resulted in an extremely high clinical response rate with relatively minor and reversible toxicity. This gave a high rate of progression-free survival and a low disease-specific progression rate. Further prospective evaluation of this treatment approach is needed to confirm the apparent clinical activity.

IMPLICATIONS FOR PRACTICE

Locally advanced basal cell cancers are challenging to treat. Previously, aggressive surgical resection or radiotherapy represented the best treatment options. Most basal cell cancers have somatic mutations in the hedgehog pathway. Oral inhibitors of this pathway produce rapid but transient clinical responses. This study reports 12 patients treated with hedgehog inhibitor induction therapy to near-maximal response. Addition of concurrent involved field radiotherapy resulted in a very high complete response rate with minimal toxicity. There was prolonged progression-free survival in 90% of patients. This study identified a novel treatment approach for patients with advanced basal cell carcinoma.