ESMO Congress 2026

Papillary renal cell carcinoma accounts for approximately 15%-20% of all kidney cancer diagnoses and is among the most common variant histology (non-clear cell) RCC subtypes ^[5]. Treatment for this population has long relied on extrapolation from clear cell RCC studies or non-subtype-specific basket trials, with dedicated evidence lacking ^[3][5]. At the level of non-clear cell RCC as a whole, evidence for ICI-based regimens, especially ICI/TKI combinations, is accumulating rapidly: KEYNOTE-B61 and ARON-1 showed consistent activity of pembrolizumab plus lenvatinib across nccRCC subtypes, and the randomized SUNNIFORECAST trial validated ipilimumab plus nivolumab as a first-line option with an overall survival benefit ^[1]. Meanwhile, TKI monotherapy is no longer recommended as first-line treatment in metastatic renal cell carcinoma; TKIs now serve mainly as a component of immunotherapy combinations, or as the first-choice alternative when immunotherapy is not tolerated ^[4]. The 2022 WHO classification also eliminated the traditional type 1/2 dichotomy of papillary RCC ^[1].

What circulated on site at this meeting (#ESMO26) was the readout of the PAPMET2 trial: the trial closed early due to slow enrollment, with 36 patients enrolled; the tweeting oncologist considered the data still very meaningful, further supporting IO/TKI doublet over TKI in papillary RCC, with higher PFS and ORR in the doublet group. Another French-language post summarized it as a small study supporting the addition of immunotherapy in papillary kidney cancer. The same post also noted that the results of STELLAR-304, SAMETA and AXIPAP are still pending, meaning PAPMET2 is not the only key dataset coming for papillary RCC.

Relative to existing knowledge, PAPMET2's advance lies in moving the evidence from pan-subtype activity signals toward subtype-specific comparison: what KEYNOTE-B61 and ARON-1 demonstrated was consistent activity of pembrolizumab plus lenvatinib across nccRCC subtypes ^[1], whereas PAPMET2 provides an efficacy signal of IO/TKI versus TKI within papillary RCC specifically (higher PFS and ORR), adding targeted data support for the preference of IO/TKI over TKI, consistent with the broader shift in non-clear cell RCC from extrapolation toward subtype-specific strategies ^[3][5].

The limitations are equally clear: only 36 patients enrolled, closed early due to slow enrollment, a very small sample; the post discloses no specific PFS or ORR values, the drug regimen used, or statistical details, so the robustness of the results remains to be confirmed. The final answer for the first-line treatment landscape in papillary RCC may still have to wait for the readouts of STELLAR-304, SAMETA and AXIPAP.