Induction Chemotherapy in Low-Risk HPV+ Oropharyngeal Cancer

OPINION STATEMENT

Human papillomavirus (HPV) associated oropharyngeal squamous cell carcinoma (OPSCC) is rapidly increasing in incidence, and has now become the most common head and neck cancer (HNC). Studies have demonstrated that HPV associated OPSCC is associated with a favorable prognosis compared with its HPV-negative counterparts, yet standard multimodality therapy is often associated with substantial acute and late treatment-related toxicity. While locoregional control is improved in HPV+ OPSCC, distant metastasis rate has gained recognition as a major cause of death in this population, with some studies suggesting similar rates as non-HPV-related cancers. Induction chemotherapy has been of long-standing interest in locoregionally advanced HNC, yet its use in combination with concomitant chemoradiation remains an area of controversy as a survival benefit remains unproven following randomized trials. Nevertheless, response to induction chemotherapy remains an important dynamic and prognostic biomarker, with response-adaptive de-intensified therapy in HPV+ OPSCC gaining traction in single-arm phase II studies demonstrating promising results. The emergence of immunotherapy in the recurrent/metastatic setting for HNC has led to enthusiasm to incorporate in the curative setting, yet its role remains undefined. Our institutional paradigm for HPV+ OPSCC incorporates induction therapy followed by risk and response adaptive locoregional treatment. Ultimately, the role of induction therapy in HPV+ OPSCC will need to be investigated in a randomized setting to be incorporated routinely into clinical practice.

Prospective study evaluating dynamic changes of cell-free HPV DNA in locoregional viral-associated oropharyngeal cancer treated with induction chemotherapy and response-adaptive treatment

BACKGROUND

Human papillomavirus (HPV)-associated oropharyngeal cancer (OPC) has a favorable prognosis which has led to efforts to de-intensify treatment. Response-adaptive de-escalated treatment is promising, however improved biomarkers are needed. Quantitative cell-free HPV-DNA (cfHPV-DNA) in plasma represents an attractive non-invasive biomarker for grading treatment response and post-treatment surveillance. This prospective study evaluates dynamic changes in cfHPV-DNA during induction therapy, definitive (chemo)radiotherapy, and post-treatment surveillance in the context of risk and response-adaptive treatment for HPV + OPC.

METHODS

Patients with locoregional HPV + OPC are stratified into two cohorts: High risk (HR) (T4, N3, [Formula: see text] 20 pack-year smoking history (PYH), or non-HPV16 subtype); Low risk (LR) (all other patients). All patients receive induction chemotherapy with three cycles of carboplatin and paclitaxel. LR with ≥ 50% response receive treatment on the single-modality arm (minimally-invasive surgery or radiation alone to 50 Gy). HR with ≥ 50% response or LR with ≥ 30% and < 50% response receive treatment on the intermediate de-escalation arm (chemoradiation to 50 Gy with cisplatin). All other patients receive treatment on the regular dose arm with chemoradiation to 70 Gy with concurrent cisplatin. Plasma cfHPV-DNA is assessed during induction, (chemo)radiation, and post-treatment surveillance. The primary endpoint is correlation of quantitative cfHPV-DNA with radiographic response.

DISCUSSION

A de-escalation treatment paradigm that reduces toxicity without compromising survival outcomes is urgently needed for HPV + OPC. Response to induction chemotherapy is predictive and prognostic and can select candidates for de-escalated definitive therapy. Assessment of quantitative cfHPV-DNA in the context of response-adaptive treatment of represents a promising reliable and convenient biomarker-driven strategy to guide personalized treatment in HPV + OPC.

TRIAL REGISTRATION

This trial is registered with ClinicalTrials.gov on October 1st, 2020 with Identifier: NCT04572100 .

Risk and response adapted de-intensified treatment for HPV-associated oropharyngeal cancer: Optima paradigm expanded experience

BACKGROUND

Favorable prognosis for Human papillomavirus-associated (HPV+) oropharyngeal cancer (OPC) led to investigation of response-adaptive de-escalation, yet long-term outcomes are unknown. We present expanded experience and follow-up of risk/response adaptive treatment de-intensification in HPV+ OPC.

METHODS

A phase 2 trial (OPTIMA) and subsequent cohort of sequential off-protocol patients treated from September 2014 to November 2018 at the University of Chicago were reviewed. Eligible patients had T3-T4 or N2-3 (AJCC 7th edition) HPV+ OPC. Patients were stratified by risk: High-risk (HR) (T4, ≥N2c, or >10PYH), all others low-risk (LR). Induction chemotherapy (IC) included 3 cycles of carboplatin and nab-paclitaxel (OPTIMA) or paclitaxel (off-protocol). LR with ≥50% response received low-dose radiotherapy (RT) alone to 50 Gy (RT50). LR with 30-50% response and HR with ≥50% response received intermediate-dose chemoradiotherapy (CRT) to 45 Gy (CRT45). All others received full-dose CRT to 75 Gy (CRT75).

RESULTS

91 patients consented and 90 patients were treated, of which 31% had >10PYH, 34% had T3/4 disease, and 94% had N2b/N2c/N3 disease. 49% were LR and 51% were HR. Overall response rate to induction was 88%. De-escalated treatment was administered to 83%. Median follow-up was 4.2 years. Five-year OS, PFS, LRC, and DC were 90% (95% CI 81,95), 90% (95% CI 80,95), 96% (95% CI 90,99), and 96% (88,99) respectively. G-tube placement rates in RT50, CRT45, and CRT75 were 3%, 33%, and 80% respectively (p < 0.05).

CONCLUSION

Risk/response adaptive de-escalated treatment for an inclusive cohort of HPV+ OPC demonstrates excellent survival with reduced toxicity with long-term follow-up.

Optimizing Treatment De-Escalation in Head and Neck Cancer: Current and Future Perspectives

Treatment of locoregionally advanced head and neck squamous cell carcinoma involves a multidisciplinary approach that combines surgery, radiotherapy, and systemic therapy. These curative strategies are associated with significant acute and long-term toxicities. With the emergence of human papillomavirus (HPV) as an etiologic factor associated primarily with oropharyngeal squamous cell carcinoma, higher cure rates juxtaposed with substantial treatment-related morbidity and mortality has led to interest in de-escalated therapeutic strategies, with the goal of optimizing oncologic outcomes while reducing treatment-related toxicity. Currently explored strategies include replacing, reducing, or omitting cytotoxic chemotherapy; reducing dose or volume of radiotherapy; and incorporation of less-invasive surgical approaches. Potential biomarkers to select patients for treatment de-escalation include clinical risk stratification, adjuvant de-escalation based on pathologic features, response to induction therapy, and molecular markers. The optimal patient selection and de-escalation strategy is critically important in the evolving treatment of locoregional head and neck cancer. Recently, two large phase III trials, RTOG 1016 and De-ESCALaTE, failed to de-escalate treatment in HPV-associated head and neck cancer by demonstrating inferior outcomes by replacing cisplatin with cetuximab in combination with radiation. This serves as a cautionary tale in the future design of de-escalation trials in this patient population, which will need to leverage toxicity and efficacy endpoints. Our review summarizes completed and ongoing de-escalation trials in head and neck cancer, with particular emphasis on biomarkers for patient selection and clinical trial design. IMPLICATIONS FOR PRACTICE: The toxicity associated with standard multimodality treatment for head and neck cancer underscores the need to seek less-intensive therapies with a reduced long-term symptom burden through de-escalated treatment paradigms that minimize toxicity while maintaining oncologic control in appropriately selected patients. Controversy regarding the optimal de-escalation strategy and criteria for patient selection for de-escalated therapy has led to multiple parallel strategies undergoing clinical investigation. Well-designed trials that optimize multimodal strategies are needed. Given the absence of positive randomized trials testing de-escalated therapy to date, practicing oncologists should exercise caution and administer established standard-of-care therapy outside the context of a clinical trial.