Concomitant Immune Check Point Inhibitor With Radiochemotherapy in Head And Neck Cancer

Among the Gulf Countries Collaboration Council (GCCC) states, HNC account for 11.5 per 100,000 population. The incidence of HNC in Kuwait is 3.8 per 100,000 population. This, as an example, accounts for about 12.7% of all cancer cases during the period from 1993 to 1999.

Rationale of Immunotherapy in Head and Neck Cancers Cancer immunotherapy principle is functional restoration of certain signaling pathways of the immune system. These pathways help to counteract different tumour evasion strategies. These may include reduced antigen processing and presentation, increased tumour-permissive cytokine profiles, creating an immunosuppressive microenvironment, cellular immune escape, and induction of non-functioning T-cells either by an increase of co-inhibitory receptors; e.g. cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) or PD-1 or decreased co-stimulatory receptors. , Immune checkpoints pathway is the most studied so far. It works by regulating the duration and extent of immune system activity through negative feedback signals. These include CTLA-4, PD-1 and PD-L1/PD-L2.

Head and neck cancers use different immune evasion mechanisms. Immune dysfunction has been implicated in carcinogenesis of human papillomavirus (HPV)-positive oropharyngeal cancer as well as cases linked to smoking.

PD-1 and PD-L1 interplay is extremely interesting. A French group from Sorbonne attempted to explain the better prognosis of HPV-positive tumours of the oropharynx. They examined PD-1 and PD-L1 expression in 64 cases, mostly of oropharyngeal origin. Infiltration of PD-1+ T-lymphocytes was a favourable prognostic factor in HPV-related disease. This also was confirmed by others, where expression of PD-L1 is common regardless of HPV status.

Safety Issues At the University of Pennsylvania, safety of ipilimumab with hypofractionated palliative radiotherapy (RT) was tested in a phase I study. There was no grade 4 or higher toxicities in the cohort of 21 patients. The most common grade 3 toxicity was anemia, that is unlikely to be related to the RT.

Anti-PD-1 agents have a better safety profile than anti-CTLA4 agents. The rate of grade 3 toxicity for pembrolizumab in NSCLC in KEYNOTE-001 was <10%, including a 1.8% rate of grade 3 pneumonitis. And in modern stereotactic body radiotherapy (SBRT) series, the rate of grade 3 radiation pneumonitis is <5%.

Interaction between Immunotherapy and Chemotherapy Classical speaking, chemotherapy (CTH) is very immune suppressive and therefore not an ideal partner for combining with vaccines (and of course other types of immunotherapy), that require an active response. Analysis of the potential interaction of CTH and immunotherapy reveals that there are many mechanisms of synergy. This suggests that the optimal treatment of cancer may include combination of immunotherapy-CTH in an optimal sequential manner.

These mechanism may include the synergistic effect of CTH in reducing tumor load and shedding antigens, as well as the inhibitory effect on regulatory cells and myeloid suppressive cells. On the other way around, immunotherapy can markedly enhance the response to CTH by activating the immune response prior to antigen release, as well as expanding activated T cells that have seen the tumor antigen.

In 2016, Langer et al published their work in the KEYNOTE-021 of combining carboplatin/pemetrexed with pembrolizumab. The combination of the chemotherapy with immunotherapy in advanced NSCLC showed tolerability as well as effectiveness. This lead to the approval of this combination in May 2017 by FDA.

Ongoing Concomitant Immunotherapy and Radiotherapy Trials in HNC Four ongoing studies are explore inhibition of the PD-1/PD-L1 in combination with definitive RT with or without cisplatin or cetuximab. These are trial: NCT02707588 assessing safety of pembrolizumab vs cetuximab in combination with radiation in non-platinum eligible patients. NCT03040999 (KEYNOTE-412) design added pembrolizumab to chemotherapy with post radiation consolidation as compared to platinum-radiation. NCT02999087 is comparing the combination of avelumab-cetuximab-radiation to cetuximab-radiation or cisplatin-radiation (REACH Trial). NCT02952586 (JAVELIN trail) is testing combination of avelumab with standard of care. RTOG 3504 examines the efficacy and safety of nivolumab in the definitive and adjuvant settings (NCT02764593). Finally, IRX-2 (citoplurikin), a primary human cell-derived biologic with multiple active cytokine components, is being tested in a randomized phase II trial of neoadjuvant and adjuvant therapy in patients with newly diagnosed curative resectable stages II, III, or IVA oral cavity cancer (NCT02609386).

Gaps in Design of ongoing Trials However, most of the studies testing the value of addition of immunotherapy to standard of care, are designed to continue immunotherapy for 4-12 months after finishing radical chemoradiation. This, in our opinion, will give mixed results and affect the conclusion of the survival benefit if found. Extrapolated from many adjuvant clinical trials, the disease control can be attributed to the length of the whole duration of treatment rather than the specific agent used. Moreover, there is no definite duration of this adjuvant immunotherapy in the ongoing trials i.e. they give a wide range of cycles and time. For example, the recruiting KEYNOTE-412 designed for 14 cycles of pembrolizumab while RTOG 3504 will try to give 7 adjuvant cycles (will be determined based on first 8 patients tolerance).

Another point in these trials design; although designed to be multicentric, most of recruiting centers are located in Europe and USA. This will limit the validity of the data and results when other countries (especially in Asia) try to adopt the treatment protocols. Based on many published data, the HNC in Eastern countries and among Asian showed different clinical and biological characteristics e.g. mostly HPV negative, related to tobacco chewing and poor nutritional status.

Lastly, the ongoing trial for nivolumab with RT in locally advanced head and neck cancer (LAHNC) is assessing the safety and efficacy. However, pembrolizumab has already published its phase Ib data extended from the large cohort of many solid tumors. In contrary, avelumab has no published supporting data (so far) regarding this indication from phase II trials. They depend largely upon their safety profiles from the pooled previous studies and/or the other subsites of diseases. As mentioned earlier, there is ongoing NCT02707588 Trial is assessing pembrolizumab safety with radiation vs cetuximab-radiation in cisplatin non-eligible patients.In the current trial, we are trying to fill this gap by testing the efficacy and safety of pembrolizumab with radical chemoradiation in all cases of LAHNC.

Post-Treatment Evaluations Post-treatment evaluations will start 4 weeks after completion of radiation therapy. The 4th week post-treatment evaluations will consist of a physical examination, hematology and biochemistry profiles, tumor assessments (by palpation) and an objective assessment of adverse events which may have occurred since completing treatment. Radiological assessment of response will be done 8-10 weeks post treatment. Responses will be reported according to irRECIST criteria.

Subsequent Follow-up evaluations will commence after the 8 week post-treatment, every four weeks (±1 week) for years one and every 8 weeks for year two, and then, every 4 months (± 2 weeks) for year three to five. The evaluations in the first year will consist of a physical examination, hematology and chemistry profiles, Quality of Life, imaging/diagnostic assessments, and tumor assessments. Evaluations in year 2-5 will consist of a physical examination, imaging/diagnostic, and tumor assessments.

Statistical methods and consideration.

• Statistical package for social sciences (SPSS) version 16. Quantitative variables will be summarized using mean and standard deviation (SD), median minimum and maximum values. Qualitative data will be summarized using frequencies and percentage.
• Overall survival will be calculated from the date of histological diagnosis.
• Progression free survival (PFS) will be calculated from the date of starting of treatment till disease progression and death whichever comes first.
• Survival analysis will be done using Kaplan- Meier, comparisons will be done using Log-rank test.
• Differences will be considered significant when p was 0.05 and highly significant when p 0.01.
• Patients lost for follow up with disease will be considered as dead.
• At the time of data analysis stratification of the patients according to sub sites, prognostic and risk factors including HPV status will be done.