Interim PET results identify aggressive NHL patients who would benefit from intensive therapy

Patient characteristics

The post-hoc analysis of the PETAL study included a total of 483 patients, of whom 397 were randomized to 6×RCHOP and 6× R-CHOP+2 R; iPET positivity was observed in 59 patients randomized to 8×(R-)CHOP or 2×(R-)CHOP and following the Burkitt regimen; Detailed patient characteristics are shown in Table 1
.
Figure 2 shows the TTP
of the Deauville scale, average SUV AI, or maximum SUV_AI dichotomous queue.

Figure 2: Deauville scores TTP for patients with different stratifications compared to average SUV AI and max-SUV_AI

Effect of intensive therapy in randomized cohorts on patient outcomes

In the interim PET-negative group, there was no statistically significant difference in TTP in patients receiving 6× RCHOP or 6× R-CHOP+2R (Figure 3A); Similarly, there was no statistically significant difference in TTP in patients treated with 8× (R-)CHOP or 2×(R-)CHOP sequential Burkitt regimens in the interim PET-positive group (Figure 4A
).

To identify patients in the iPET-negative subgroup who would benefit from additional rituximab intensive therapy

The optimal average SUV_AI threshold (SUV 4.
89) for patient stratification in the interim PET-negative subgroup was used to group patients into high versus low PET uptake groups (Figure 3).

Among patients with high average SUV_AI, TTP was significantly longer in patients treated with 6× R-CHOP+2 R than in patients treated with 6× R-CHOP (median TTP was less than 52 months; p<0.
05).

This is not the case with the conventional indicator max-SUVmanual or the decline in SUVmax between baseline and mid-term PET (Figure 3), so it is not possible to identify subgroups
that benefit from therapeutic interventions.

Figure 3: Efficacy of additional rituximab in patients with negative interim PET scan

Identify patients in the iPET-positive subgroup who could not benefit from the Burkitt intensive regimen

In a multivariate Cox regression analysis with corrected treatment regimens [8×(R-)CHOP vs 2×(R-)CHOP followed by Burkitt protocol], mean SUV AI, and IPI scores, the interaction term (treatment regimen × mean SUV_AI) was not a statistically significant predictor of TTP (p>0.
05).

However, average SUV_AI is a statistically significant predictor of TTP (p<0.
05).

The optimal average SUV_{AI threshold (}SUV 4.
78) stratified by patients in the medium-term PET-positive subgroup was used to divide patients into high uptake and low uptake groups
.
All patients
randomized to either ×(R-)CHOP or 2×(R-)CHOP followed by the Burkitt regimen were further analyzed.
In the average SUV_AI high uptake group, patients treated with Burkitt regimen had significantly shorter TTPs than those who continued to receive (R-)CHOP, with median TTPs of 4 vs 14 months (p<0.
01; Figure 5),
respectively.
In addition, the extent of the decline in SUVmax between baseline and mid-term PET by conventional PET metric max-SUVmanual can also determine subgroup patients who receive a subgroup of patients receiving the Burkitt regimen with a poor prognosis (Figure 4).

In patients with low mean SUV_AI, no statistically significant difference in TTP between treatment groups was observed (median TTP 28 versus 30 months, respectively; p>0.
05）
。

Figure 4: Prognostic effect of Burkitt regimen intensive therapy in the subgroup of patients with positive interim PET scan